Search

Your search keyword '"HAMAD, AI"' showing total 459 results
Start Over Author "HAMAD, AI"
459 results on '"HAMAD, AI"'

1. Pair invariant mass to isolate background in the search for the chiral magnetic effect in Au + Au collisions at sNN=200 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Nuclear and plasma physics
Abstract

Quark interactions with topological gluon configurations can induce local chirality imbalance and parity violation in quantum chromodynamics, which can lead to the chiral magnetic effect (CME) - an electric charge separation along the strong magnetic field in relativistic heavy-ion collisions. The CME-sensitive azimuthal correlator observable (Δγ) is contaminated by background arising, in part, from resonance decays coupled with elliptic anisotropy (v2). We report here differential measurements of the correlator as a function of the pair invariant mass (minv) in 20-50% centrality Au+Au collisions at sNN=200 GeV by the STAR experiment at the BNL Relativistic Heavy Ion Collider. Strong resonance background contributions to Δγ are observed. At large minv where this background is significantly reduced, the Δγ value is found to be significantly smaller. An event-shape-engineering technique is deployed to determine the v2 background shape as a function of minv. We extract a v2-independent and minv-averaged signal Δγsig=(0.03±0.06±0.08)×10-4, or (2±4±5)% of the inclusive Δγ(minv>0.4 GeV/c2)=(1.58±0.02±0.02)×10-4, within pion pT=0.2-0.8 GeV/c and averaged over pseudorapidity ranges of -1

Published
2022

2. Measurements of Proton High-Order Cumulants in sNN=3 GeV Au+Au Collisions and Implications for the QCD Critical Point

Author

Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, STAR Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

We report cumulants of the proton multiplicity distribution from dedicated fixed-target Au+Au collisions at sqrt[s_{NN}]=3.0  GeV, measured by the STAR experiment in the kinematic acceptance of rapidity (y) and transverse momentum (p_{T}) within -0.5

Published
2022

3. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at s=510 GeV

Author

Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences
Abstract

We report measurements of the longitudinal double-spin asymmetry, ALL, for inclusive jet and dijet production in polarized proton-proton collisions at midrapidity and center-of-mass energy s=510 GeV, using the high luminosity data sample collected by the STAR experiment in 2013. These measurements complement and improve the precision of previous STAR measurements at the same center-of-mass energy that probe the polarized gluon distribution function at partonic momentum fraction 0.015≲x≲0.25. The dijet asymmetries are separated into four jet-pair topologies, which provide further constraints on the x dependence of the polarized gluon distribution function. These measurements are in agreement with previous STAR measurements and with predictions from current next-to-leading-order global analyses. They provide more precise data at low dijet invariant mass that will better constrain the shape of the polarized gluon distribution function of the proton.

Published
2022

4. Differential measurements of jet substructure and partonic energy loss in Au + Au collisions at sNN=200 GeV

Author

Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Nuclear and plasma physics
Abstract

The STAR collaboration presents jet substructure measurements related to both the momentum fraction and the opening angle within jets in p+p and Au+Au collisions at sNN =200GeV. The substructure observables include SoftDrop groomed momentum fraction (zg), groomed jet radius (Rg), and subjet momentum fraction (zSJ) and opening angle (θSJ). The latter observable is introduced for the first time. Fully corrected subjet measurements are presented for p+p collisions and are compared to leading-order Monte Carlo models. The subjet θSJ distributions reflect the jets leading opening angle and are utilized as a proxy for the resolution scale of the medium in Au+Au collisions. We compare data from Au+Au collisions to those from p+p which are embedded in minimum-bias Au+Au events in order to include the effects of detector smearing and the heavy-ion collision underlying event. The subjet observables are shown to be more robust to the background than zg and Rg. We observe no significant modifications of the subjet observables within the two highest-energy, back-to-back jets, resulting in a distribution of opening angles and the splittings that are vacuumlike. We also report measurements of the differential dijet momentum imbalance (AJ) for jets of varying θSJ. We find no qualitative differences in energy loss signatures for varying angular scales in the range 0.1< θSJ

Published
2022

5. Search for the Chiral Magnetic Effect via Charge-Dependent Azimuthal Correlations Relative to Spectator and Participant Planes in Au+Au Collisions at sNN=200 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, Harabasz, S, and Harasty, MD

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, STAR Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

The chiral magnetic effect (CME) refers to charge separation along a strong magnetic field due to imbalanced chirality of quarks in local parity and charge-parity violating domains in quantum chromodynamics. The experimental measurement of the charge separation is made difficult by the presence of a major background from elliptic azimuthal anisotropy. This background and the CME signal have different sensitivities to the spectator and participant planes, and could thus be determined by measurements with respect to these planes. We report such measurements in Au+Au collisions at a nucleon-nucleon center-of-mass energy of 200 GeV at the Relativistic Heavy-Ion Collider. It is found that the charge separation, with the flow background removed, is consistent with zero in peripheral (large impact parameter) collisions. Some indication of finite CME signals is seen in midcentral (intermediate impact parameter) collisions. Significant residual background effects may, however, still be present.

Published
2022

6. Measurement of cold nuclear matter effects for inclusive J/ψ in p+Au collisions at s NN = 200 GeV

Author

Collaboration, STAR, Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, and Hamad, AI

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, RHIC, Cold nuclear matter effects, J/psi suppression, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Mathematical sciences, Physical sciences
Abstract

Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive J/ψ at mid-rapidity in 0-100% p+Au collisions at sNN = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, RpAu, obtained by taking a ratio of J/ψ yield in p+Au collisions to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The differential J/ψ yield in both p+p and p+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the J/ψ RpAu is derived within the transverse momentum (pT) range of 0 to 10 GeV/c. A suppression of approximately 30% is observed for pT

Published
2022

7. Search for the chiral magnetic effect with isobar collisions at sNN=200 GeV by the STAR Collaboration at the BNL Relativistic Heavy Ion Collider

Author

Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Nuclear and plasma physics
Abstract

The chiral magnetic effect (CME) is predicted to occur as a consequence of a local violation of P and CP symmetries of the strong interaction amidst a strong electromagnetic field generated in relativistic heavy-ion collisions. Experimental manifestation of the CME involves a separation of positively and negatively charged hadrons along the direction of the magnetic field. Previous measurements of the CME-sensitive charge-separation observables remain inconclusive because of large background contributions. To better control the influence of signal and backgrounds, the STAR Collaboration performed a blind analysis of a large data sample of approximately 3.8 billion isobar collisions of Ru4496+Ru4496 and Zr4096+Zr4096 at sNN=200 GeV. Prior to the blind analysis, the CME signatures are predefined as a significant excess of the CME-sensitive observables in Ru+Ru collisions over those in Zr+Zr collisions, owing to a larger magnetic field in the former. A precision down to 0.4% is achieved, as anticipated, in the relative magnitudes of the pertinent observables between the two isobar systems. Observed differences in the multiplicity and flow harmonics at the matching centrality indicate that the magnitude of the CME background is different between the two species. No CME signature that satisfies the predefined criteria has been observed in isobar collisions in this blind analysis.

Published
2022

8. Global Λ-hyperon polarization in Au+Au collisions at sNN=3 GeV

Author

Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, and Hamad, AI

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Nuclear and plasma physics
Abstract

Global hyperon polarization, P¯H, in Au+Au collisions over a large range of collision energy, sNN, was recently measured and successfully reproduced by hydrodynamic and transport models with intense fluid vorticity of the quark-gluon plasma. While naïve extrapolation of data trends suggests a large P¯H as the collision energy is reduced, the behavior of P¯H at small sNN

Published
2021

9. Invariant jet mass measurements in pp collisions at s =200 GeV at RHIC

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, De La Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Abstract

We present the first inclusive measurements of the invariant and softdrop jet mass in proton-proton collisions at s=200 GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned pythia-6 reproduces the data, while LHC tunes of pythia-8 and herwig-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that softdrop grooming, for which the contribution of wide-angle nonperturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both pythia-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

Published
2021

10. Invariant jet mass measurements in pp collisions at s=200 GeV at RHIC

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences
Abstract

We present the first inclusive measurements of the invariant and softdrop jet mass in proton-proton collisions at s=200 GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned pythia-6 reproduces the data, while LHC tunes of pythia-8 and herwig-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that softdrop grooming, for which the contribution of wide-angle nonperturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both pythia-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

Published
2021

11. Cumulants and correlation functions of net-proton, proton, and antiproton multiplicity distributions in Au+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, nucl-ex, hep-ex, hep-ph, nucl-th, Nuclear and plasma physics
Abstract

We report a systematic measurement of cumulants, Cn, for net-proton, proton, and antiproton multiplicity distributions, and correlation functions, κn, for proton and antiproton multiplicity distributions up to the fourth order in Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, and 200 GeV. The Cn and κn are presented as a function of collision energy, centrality and kinematic acceptance in rapidity, y, and transverse momentum, pT. The data were taken during the first phase of the Beam Energy Scan (BES) program (2010-2017) at the BNL Relativistic Heavy Ion Collider (RHIC) facility. The measurements are carried out at midrapidity (|y|< 0.5) and transverse momentum 0.4

Published
2021

12. Azimuthal anisotropy measurements of strange and multistrange hadrons in U+U collisions at sNN=193 GeV at the BNL Relativistic Heavy Ion Collider

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, Nuclear and plasma physics
Abstract

We present systematic measurements of azimuthal anisotropy for strange and multistrange hadrons (Ks0, Λ, Ξ, and ω) and φ mesons at midrapidity (|y|< 1.0) in collisions of U+U nuclei at sNN=193 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. Transverse momentum (pT) dependence of flow coefficients (v2, v3, and v4) is presented for minimum bias collisions and three different centrality intervals. Number of constituent quark scaling of the measured flow coefficients in U+U collisions is discussed. We also present the ratio of vn scaled by the participant eccentricity (ɛn2) to explore system size dependence and collectivity in U+U collisions. The magnitude of v2/ɛ2 is found to be smaller in U+U collisions than that in central Au+Au collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics (v3/v23/2, v4/v24/2) are studied and compared with hydrodynamic and transport model calculations.

Published
2021

13. Azimuthal anisotropy measurements of strange and multistrange hadrons in U+ U collisions at sNN =193 GeV at the BNL Relativistic Heavy Ion Collider

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Abstract

We present systematic measurements of azimuthal anisotropy for strange and multistrange hadrons (Ks0, Λ, Ξ, and ω) and φ mesons at midrapidity (|y|< 1.0) in collisions of U+U nuclei at sNN=193 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. Transverse momentum (pT) dependence of flow coefficients (v2, v3, and v4) is presented for minimum bias collisions and three different centrality intervals. Number of constituent quark scaling of the measured flow coefficients in U+U collisions is discussed. We also present the ratio of vn scaled by the participant eccentricity (ɛn2) to explore system size dependence and collectivity in U+U collisions. The magnitude of v2/ɛ2 is found to be smaller in U+U collisions than that in central Au+Au collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics (v3/v23/2, v4/v24/2) are studied and compared with hydrodynamic and transport model calculations.

Published
2021

14. Measurement of transverse single-spin asymmetries of π0 and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions MEASUREMENT of TRANSVERSE SINGLE-SPIN ASYMMETRIES ⋯ ADAM J. et al.

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, and Holub, L

Subjects
hep-ex
Abstract

The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive π0 at center-of-mass energies (s) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-x, and, when compared to previous measurements, no dependence on s from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. π0 with no nearby particles tend to have a higher TSSA than inclusive π0. The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive π0 asymmetry as a function of Feynman-x. To investigate final-state effects, the Collins asymmetry of π0 inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the π0 momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the π0. The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.

Published
2021

15. Methods for a blind analysis of isobar data collected by the STAR collaboration

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S

Subjects
Blind analysis, Chiral magnetic effect, Heavy-ion collisions, nucl-ex, hep-ex, Nuclear & Particles Physics
Abstract

In 2018, the STAR collaboration collected data from 4496Ru+4496Ru and 4096Zr+4096Zr at sNN=200 GeV to search for the presence of the chiral magnetic effect in collisions of nuclei. The isobar collision species alternated frequently between 4496Ru+4496Ru and 4096Zr+4096Zr. In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data, STAR developed a three-step blind analysis procedure. Analysts are initially provided a “reference sample” of data, comprised of a mix of events from the two species, the order of which respects time-dependent changes in run conditions. After tuning analysis codes and performing time-dependent quality assurance on the reference sample, analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual ≈ 30 -min data-taking runs. For this sample, species-specific information is disguised, but individual output files contain data from a single isobar species. Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage. Following these modifications, the “frozen” code is passed over the fully un-blind data, completing the blind analysis. As a check of the feasibility of the blind analysis procedure, analysts completed a “mock data challenge,” analyzing data from Au + Au collisions at sNN=27 GeV, collected in 2018. The Au + Au data were prepared in the same manner intended for the isobar blind data. The details of the blind analysis procedure and results from the mock data challenge are presented.

Published
2021

16. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at s=200 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Sciences, Physical Sciences, hep-ex, nucl-ex
Abstract

We report high-precision measurements of the longitudinal double-spin asymmetry, ALL, for midrapidity inclusive jet and dijet production in polarized pp collisions at a center-of-mass energy of s=200 GeV. The new inclusive jet data are sensitive to the gluon helicity distribution, Δg(x,Q2), for gluon momentum fractions in the range from x≃0.05 to x≃0.5, while the new dijet data provide further constraints on the x dependence of Δg(x,Q2). The results are in good agreement with previous measurements at s=200 GeV and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that Δg(x,Q2) is positive for x>0.05.

Published
2021

17. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at s =200 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S

Subjects
hep-ex, nucl-ex
Abstract

We report high-precision measurements of the longitudinal double-spin asymmetry, ALL, for midrapidity inclusive jet and dijet production in polarized pp collisions at a center-of-mass energy of s=200 GeV. The new inclusive jet data are sensitive to the gluon helicity distribution, Δg(x,Q2), for gluon momentum fractions in the range from x≃0.05 to x≃0.5, while the new dijet data provide further constraints on the x dependence of Δg(x,Q2). The results are in good agreement with previous measurements at s=200 GeV and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that Δg(x,Q2) is positive for x>0.05.

Published
2021

18. Global Polarization of Ξ and Ω Hyperons in Au+Au Collisions at sNN=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, and Hong, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, STAR Collaboration, nucl-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at sqrt[s_{NN}]=200  GeV. The measurements of the Ξ^{-} and Ξ[over ¯]^{+} hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over Ξ^{-} and Ξ[over ¯]^{+}, is measured to be ⟨P_{Ξ}⟩=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The ⟨P_{Ξ}⟩ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The ⟨P_{Ξ}⟩ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of Ω, ⟨P_{Ω}⟩=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor C_{ΩΛ}=1.

Published
2021

19. Comparison of transverse single-spin asymmetries for forward π0 production in polarized pp, pAl and pAu collisions at nucleon pair c.m. energy sNN =200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, and Hong, Y

Subjects
nucl-ex, hep-ex
Abstract

The STAR collaboration reports a measurement of the transverse single-spin asymmetries, AN, for neutral pions produced in polarized proton collisions with protons (pp), with aluminum nuclei (pAl) and with gold nuclei (pAu) at a nucleon-nucleon center-of-mass energy of 200 GeV. Neutral pions are observed in the forward direction relative to the transversely polarized proton beam, in the pseudorapidity region 2.7

Published
2021

20. Comparison of transverse single-spin asymmetries for forward π0 production in polarized pp, pAl and pAu collisions at nucleon pair c.m. energy sNN=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, and Hong, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, nucl-ex, hep-ex
Abstract

The STAR collaboration reports a measurement of the transverse single-spin asymmetries, AN, for neutral pions produced in polarized proton collisions with protons (pp), with aluminum nuclei (pAl) and with gold nuclei (pAu) at a nucleon-nucleon center-of-mass energy of 200 GeV. Neutral pions are observed in the forward direction relative to the transversely polarized proton beam, in the pseudorapidity region 2.7

Published
2021

21. Nonmonotonic Energy Dependence of Net-Proton Number Fluctuations

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, STAR Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

Nonmonotonic variation with collision energy (sqrt[s_{NN}]) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the quantum chromodynamics critical point. We report the first evidence of a nonmonotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of sqrt[s_{NN}] with 3.1  σ significance for head-on (central) gold-on-gold (Au+Au) collisions measured solenoidal tracker at Relativistic Heavy Ion Collider. Data in noncentral Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of sqrt[s_{NN}].

Published
2021

22. Flow and interferometry results from Au+Au collisions at sNN =4.5 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, and Hamad, AI

Subjects
nucl-ex
Abstract

The beam energy scan (BES) program at the BNL Relativistic Heavy Ion Collider (RHIC) was extended to energies below sNN=7.7 GeV in 2015 by successful implementation of the fixed-target mode of operation in the STAR (Solenoidal Tracker At RHIC) experiment. In this mode, ions circulate in one ring of the collider and interact with a stationary target at the entrance of the STAR time projection chamber. The first results for Au+Au collisions at sNN=4.5 GeV are presented, demonstrating good performance of all the relevant detector subsystems in fixed-target mode. Results presented here include directed and elliptic flow of identified hadrons, and radii from pion femtoscopy. The latter, together with recent HADES results, reveal a long-sought peak structure that may be caused by the system evolving through a first-order phase transition from quark-gluon plasma to the hadronic phase. Directed and elliptic flow for pions are presented for the first time at this beam energy. Pion and proton elliptic flow show behavior which hints at constituent quark scaling, and demonstrate that a definitive conclusion will be achievable using the full statistics of the ongoing second phase of BES (BES-II). In particular, BES-II to date has recorded fixed-target data sets with two orders of magnitude more events at each of nine energies between sNN=3.0 and 7.7 GeV.

Published
2021

23. Flow and interferometry results from Au+Au collisions at sNN=4.5 GeV

Author

Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, and Hamad, AI

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract

The beam energy scan (BES) program at the BNL Relativistic Heavy Ion Collider (RHIC) was extended to energies below sNN=7.7 GeV in 2015 by successful implementation of the fixed-target mode of operation in the STAR (Solenoidal Tracker At RHIC) experiment. In this mode, ions circulate in one ring of the collider and interact with a stationary target at the entrance of the STAR time projection chamber. The first results for Au+Au collisions at sNN=4.5 GeV are presented, demonstrating good performance of all the relevant detector subsystems in fixed-target mode. Results presented here include directed and elliptic flow of identified hadrons, and radii from pion femtoscopy. The latter, together with recent HADES results, reveal a long-sought peak structure that may be caused by the system evolving through a first-order phase transition from quark-gluon plasma to the hadronic phase. Directed and elliptic flow for pions are presented for the first time at this beam energy. Pion and proton elliptic flow show behavior which hints at constituent quark scaling, and demonstrate that a definitive conclusion will be achievable using the full statistics of the ongoing second phase of BES (BES-II). In particular, BES-II to date has recorded fixed-target data sets with two orders of magnitude more events at each of nine energies between sNN=3.0 and 7.7 GeV.

Published
2021

24. Observation of $D_{s}^{\pm}/D^0$ enhancement in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV

Author

Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Sánchez, M Calderón de la Barca, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, and Hoffman, E

Subjects
hep-ex
Abstract

We report on the first measurement of charm-strange meson $D_s^{\pm}$production at midrapidity in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200GeV from the STAR experiment. The yield ratio between strange ($D_{s}^{\pm}$)and non-strange ($D^{0}$) open-charm mesons is presented and compared to modelcalculations. A significant enhancement, relative to a PYTHIA simulation of$p$+$p$ collisions, is observed in the $D_{s}^{\pm}/D^0$ yield ratio in Au+Aucollisions over a large range of collision centralities. Model calculationsincorporating abundant strange-quark production in the quark-gluon plasma (QGP)and coalescence hadronization qualitatively reproduce the data. Thetransverse-momentum integrated yield ratio of $D_{s}^{\pm}/D^0$ at midrapidityis consistent with a prediction from a statistical hadronization model with theparameters constrained by the yields of light and strange hadrons measured atthe same collision energy. These results suggest that the coalescence of charmquarks with strange quarks in the QGP plays an important role in $D_{s}^{\pm}$meson production in heavy-ion collisions.

Published
2021

25. Measurements of W and Z /γ∗ cross sections and their ratios in p+p collisions at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S

Subjects
nucl-ex, hep-ex
Abstract

We report on the W and Z/γ∗ differential and total cross sections as well as the W+/W- and (W++W-)/(Z/γ∗) cross section ratios measured by the STAR experiment at RHIC in p+p collisions at s=500 GeV and 510 GeV. The cross sections and their ratios are sensitive to quark and antiquark parton distribution functions. In particular, at leading order, the W cross section ratio is sensitive to the d¯/ū ratio. These measurements were taken at high Q2∼MW2,MZ2 and can serve as input into global analyses to provide constraints on the sea quark distributions. The results presented here combine three STAR datasets from 2011, 2012, and 2013, accumulating an integrated luminosity of 350 pb-1. We also assess the expected impact that our W+/W- cross section ratios will have on various quark distributions, and find sensitivity to the ū-d¯ and d¯/ū distributions.

Published
2021

26. Measurements of W and Z/γ* cross sections and their ratios in p+p collisions at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex
Abstract

We report on the W and Z/γ∗ differential and total cross sections as well as the W+/W- and (W++W-)/(Z/γ∗) cross section ratios measured by the STAR experiment at RHIC in p+p collisions at s=500 GeV and 510 GeV. The cross sections and their ratios are sensitive to quark and antiquark parton distribution functions. In particular, at leading order, the W cross section ratio is sensitive to the d¯/ū ratio. These measurements were taken at high Q2∼MW2,MZ2 and can serve as input into global analyses to provide constraints on the sea quark distributions. The results presented here combine three STAR datasets from 2011, 2012, and 2013, accumulating an integrated luminosity of 350 pb-1. We also assess the expected impact that our W+/W- cross section ratios will have on various quark distributions, and find sensitivity to the ū-d¯ and d¯/ū distributions.

Published
2021

27. Measurement of groomed jet substructure observables in p+p collisions at s=200 GeV with STAR

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Jet substructure, SoftDrop, Splitting function, Groomed jet radius, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at s=200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R=0.2−0.6 in the transverse momentum range 15

Published
2020

28. Measurement of groomed jet substructure observables in p+p collisions at s = 200 GeV with STAR

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Jet substructure, SoftDrop, Splitting function, Groomed jet radius, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Mathematical sciences, Physical sciences
Abstract

In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at s=200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R=0.2−0.6 in the transverse momentum range 15

Published
2020

29. Measurement of inclusive charged-particle jet production in Au + Au collisions at sNN =200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ

Subjects
nucl-ex, hep-ex
Abstract

The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at sNN=200 GeV. Jets are reconstructed with the anti-kT algorithm using charged tracks with pseudorapidity |η|

Published
2020

30. Measurement of inclusive J/ψ polarization in p+p collisions at s =200 GeV by the STAR experiment

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
hep-ex, nucl-ex
Abstract

We report on new measurements of inclusive J/ψ polarization at midrapidity in p+p collisions at s=200 GeV by the STAR experiment at the Relativistic Heavy Ion Collider. The polarization parameters, λθ, λφ, and λθφ, are measured as a function of transverse momentum (pT) in both the helicity and Collins-Soper (CS) reference frames within pT

Published
2020

31. Measurement of inclusive charged-particle jet production in Au + Au collisions at sNN=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex, Nuclear and plasma physics
Abstract

The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at sNN=200 GeV. Jets are reconstructed with the anti-kT algorithm using charged tracks with pseudorapidity |η|

Published
2020

32. Measurement of inclusive J/ψ polarization in p+p collisions at s=200 GeV by the STAR experiment

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, nucl-ex
Abstract

We report on new measurements of inclusive J/ψ polarization at midrapidity in p+p collisions at s=200 GeV by the STAR experiment at the Relativistic Heavy Ion Collider. The polarization parameters, λθ, λφ, and λθφ, are measured as a function of transverse momentum (pT) in both the helicity and Collins-Soper (CS) reference frames within pT

Published
2020

33. Beam-energy dependence of the directed flow of deuterons in Au+Au collisions

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
nucl-ex
Abstract

We present a measurement of the first-order azimuthal anisotropy v1 of deuterons from Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, and 39 GeV recorded with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The energy dependence of the v1(y) slope, dv1/dy|y=0, for deuterons, where y is the rapidity, is extracted for semicentral collisions (10%-40% centrality) and compared with that of protons. While the v1(y) slopes of protons are generally negative for sNN>10GeV, those for deuterons are consistent with zero, a strong enhancement of the v1(y) slope of deuterons is seen at the lowest collision energy (the largest baryon density) at sNN=7.7GeV. In addition, we report the transverse momentum dependence of v1 for protons and deuterons. The experimental results are compared with transport and coalescence models.

Published
2020

34. Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at sNN = 200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Collectivity, Correlation, Shear viscosity, nucl-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract

Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.

Published
2020

35. Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at √sNN = 200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, De La Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
di-hadron correlations, jet, heavy-ion, nucl-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

High transverse momentum (PT) particle production is suppressed owing to the parton (jet) energy loss in the hot dense medium created in relativistic heavy-ion collisions. Redistribution of energy at low-to-modest PT has been difficult to measure, owing to large anisotropic backgrounds. We report a data-driven method for background evaluation and subtraction, exploiting the away-side pseudorapidity gaps, to measure the jetlike correlation shape in Au+Au collisions at √SNN = 200 GeV in the STAR experiment. The correlation shapes, for trigger particles and various associated particle PT ranges within, are consistent with Gaussians, and their widths increase with centrality. The results indicate jet broadening in the medium created in central heavy-ion collisions.

Published
2020

36. Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, di-hadron correlations, jet, heavy-ion, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Atomic, molecular and optical physics, Particle and high energy physics
Abstract

High transverse momentum (PT) particle production is suppressed owing to the parton (jet) energy loss in the hot dense medium created in relativistic heavy-ion collisions. Redistribution of energy at low-to-modest PT has been difficult to measure, owing to large anisotropic backgrounds. We report a data-driven method for background evaluation and subtraction, exploiting the away-side pseudorapidity gaps, to measure the jetlike correlation shape in Au+Au collisions at √SNN = 200 GeV in the STAR experiment. The correlation shapes, for trigger particles and various associated particle PT ranges within, are consistent with Gaussians, and their widths increase with centrality. The results indicate jet broadening in the medium created in central heavy-ion collisions.

Published
2020

37. Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at s N N = 200 GeV

Author

Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, and Hu, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Collectivity, Correlation, Shear viscosity, nucl-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Mathematical sciences, Physical sciences
Abstract

Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.

Published
2020

38. Results on total and elastic cross sections in proton–proton collisions at s=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Elastic scattering, Diffraction, Proton-proton collisions, hep-ex, nucl-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

We report results on the total and elastic cross sections in proton-proton collisions at s=200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045≤−t≤0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt∼e−Bt in the measured −t range was found to be B=14.32±0.09(stat.)−0.28+0.13(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t=0, is σtot=54.67±0.21(stat.)−1.38+1.28(syst.) mb. We also present the values of the elastic cross section σel=10.85±0.03(stat.)−0.41+0.49(syst.) mb, the elastic cross section integrated within the STAR t-range σeldet=4.05±0.01(stat.)−0.17+0.18(syst.) mb, and the inelastic cross section σinel=43.82±0.21(stat.)−1.44+1.37(syst.) mb. The results are compared with the world data.

Published
2020

39. Strange hadron production in Au+Au collisions at sNN=7.7, 11.5, 19.6, 27, and 39 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, and Huang, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract

We present STAR measurements of strange hadron (KS0, Λ, Λ, Ξ-, Ξ+, ω-, ω+, and φ) production at midrapidity (|y|

Published
2020

40. Strange hadron production in Au+Au collisions at sNN =7.7, 11.5, 19.6, 27, and 39 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, and Huang, T

Subjects
nucl-ex
Abstract

We present STAR measurements of strange hadron (KS0, Λ, Λ, Ξ-, Ξ+, ω-, ω+, and φ) production at midrapidity (|y|

Published
2020

41. Results on total and elastic cross sections in proton–proton collisions at s = 200 GeV

Author

Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, and Hu, Y

Subjects
Elastic scattering, Diffraction, Proton-proton collisions, hep-ex, nucl-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract

We report results on the total and elastic cross sections in proton-proton collisions at s=200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045≤−t≤0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt∼e−Bt in the measured −t range was found to be B=14.32±0.09(stat.)−0.28+0.13(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t=0, is σtot=54.67±0.21(stat.)−1.38+1.28(syst.) mb. We also present the values of the elastic cross section σel=10.85±0.03(stat.)−0.41+0.49(syst.) mb, the elastic cross section integrated within the STAR t-range σeldet=4.05±0.01(stat.)−0.17+0.18(syst.) mb, and the inelastic cross section σinel=43.82±0.21(stat.)−1.44+1.37(syst.) mb. The results are compared with the world data.

Published
2020

42. Beam energy dependence of net-Λ fluctuations measured by the STAR experiment at the BNL Relativistic Heavy Ion Collider

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, Huang, X, and Humanic, TJ

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex, hep-ph, nucl-th, Nuclear and plasma physics
Abstract

The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the quantum chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. Net-protons and net-kaons have been used as proxies for the net-baryon number and net-strangeness, respectively. We report the measurement of efficiency- and centrality-bin width-corrected cumulant ratios (C2/C1, C3/C2) of net-Λ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality, and rapidity. The results are for Au+Au collisions at five beam energies (sNN=19.6, 27, 39, 62.4, and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to ultrarelativistic quantum molecular dynamics (UrQMD) and hadron resonance gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. UrQMD describes the measured net-ΛC1 and C3 at 200 GeV reasonably well but deviates from C2, and the deviation increases as a function of collision energy. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon, and net-charge data, indicate Λ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing with temperatures obtained from net-proton fluctuations. The net-Λ cumulants show a weak but finite dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.

Published
2020

43. Measurement of the central exclusive production of charged particle pairs in proton-proton collisions at s = 200 GeV with the STAR detector at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, Diffraction, Forward physics, Hadron-Hadron scattering, hep-ex, nucl-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract

We report on the measurement of the Central Exclusive Production of charged particle pairs h+h− (h = π, K, p) with the STAR detector at RHIC in proton-proton collisions at s = 200 GeV. The charged particle pairs produced in the reaction pp → p′ + h+h− + p′ are reconstructed from the tracks in the central detector and identified using the specific energy loss and the time of flight method, while the forward-scattered protons are measured in the Roman Pot system. Exclusivity of the event is guaranteed by requiring the transverse momentum balance of all four final-state particles. Differential cross sections are measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. They are measured in a fiducial region corresponding to the acceptance of the STAR detector and determined by the central particles’ transverse momenta and pseudorapidities as well as by the forward-scattered protons’ momenta. This fiducial region roughly corresponds to the square of the four-momentum transfers at the proton vertices in the range 0.04 GeV2< −t1, −t2< 0.2 GeV2, invariant masses of the charged particle pairs up to a few GeV and pseudorapidities of the centrally-produced hadrons in the range |η| < 0.7. The measured cross sections are compared to phenomenological predictions based on the Double Pomeron Exchange (DPE) model. Structures observed in the mass spectra of π+π− and K+K− pairs are consistent with the DPE model, while angular distributions of pions suggest a dominant spin-0 contribution to π+π− production. For π+π− production, the fiducial cross section is extrapolated to the Lorentz-invariant region, which allows decomposition of the invariant mass spectrum into continuum and resonant contributions. The extrapolated cross section is well described by the continuum production and at least three resonances, the f0(980), f2(1270) and f0(1500), with a possible small contribution from the f0(1370). Fits to the extrapolated differential cross section as a function of t1 and t2 enable extraction of the exponential slope parameters in several bins of the invariant mass of π+π− pairs. These parameters are sensitive to the size of the interaction region. [Figure not available: see fulltext.].

Published
2020

44. Measurement of D0 -meson + hadron two-dimensional angular correlations in Au+ Au collisions at sNN =200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
nucl-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

Open heavy-flavor hadrons provide unique probes of the medium produced in ultrarelativistic heavy-ion collisions. Due to their increased mass relative to light-flavor hadrons, long lifetime, and early production in hard-scattering interactions, they provide access to the full evolution of the partonic medium formed in heavy-ion collisions. This paper reports two-dimensional (2D) angular correlations between neutral D mesons and unidentified charged particles produced in minimum-bias Au+Au collisions at sNN=200GeV. D0 and D¯0 mesons are reconstructed via their weak decay to Kπ± using the Heavy Flavor Tracker in the Solenoidal Tracker at RHIC experiment. Correlations on relative pseudorapidity and azimuth (Δη,Δφ) are presented for peripheral, midcentral, and central collisions with D0 transverse momentum from 2-10GeV/c. Attention is focused on the 2D peaked correlation structure near the triggered D0 meson, the near-side (NS) peak, which serves as a proxy for a charm-quark-containing jet. The correlated NS yield of charged particles per D0 meson and the 2D widths of the NS peak increase significantly from peripheral to central collisions. These results are compared with similar correlations using unidentified charged particles, consisting primarily of light-flavor hadrons, at similar trigger particle momenta. Similar per-trigger yields and widths of the NS correlation peak are observed. The present results provide additional evidence that D0 mesons undergo significant interactions with the medium formed in heavy-ion collision and show, for the first time, significant centrality evolution of the NS 2D peak in the correlations of particles associated with a heavy-flavor hadron produced in these collisions.

Published
2020

45. Measurement of the central exclusive production of charged particle pairs in proton-proton collisions at √s = 200 GeV with the STAR detector at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ

Subjects
Diffraction, Forward physics, Hadron-Hadron scattering, hep-ex, nucl-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

We report on the measurement of the Central Exclusive Production of charged particle pairs h+h− (h = π, K, p) with the STAR detector at RHIC in proton-proton collisions at s = 200 GeV. The charged particle pairs produced in the reaction pp → p′ + h+h− + p′ are reconstructed from the tracks in the central detector and identified using the specific energy loss and the time of flight method, while the forward-scattered protons are measured in the Roman Pot system. Exclusivity of the event is guaranteed by requiring the transverse momentum balance of all four final-state particles. Differential cross sections are measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. They are measured in a fiducial region corresponding to the acceptance of the STAR detector and determined by the central particles’ transverse momenta and pseudorapidities as well as by the forward-scattered protons’ momenta. This fiducial region roughly corresponds to the square of the four-momentum transfers at the proton vertices in the range 0.04 GeV2< −t1, −t2< 0.2 GeV2, invariant masses of the charged particle pairs up to a few GeV and pseudorapidities of the centrally-produced hadrons in the range |η| < 0.7. The measured cross sections are compared to phenomenological predictions based on the Double Pomeron Exchange (DPE) model. Structures observed in the mass spectra of π+π− and K+K− pairs are consistent with the DPE model, while angular distributions of pions suggest a dominant spin-0 contribution to π+π− production. For π+π− production, the fiducial cross section is extrapolated to the Lorentz-invariant region, which allows decomposition of the invariant mass spectrum into continuum and resonant contributions. The extrapolated cross section is well described by the continuum production and at least three resonances, the f0(980), f2(1270) and f0(1500), with a possible small contribution from the f0(1370). Fits to the extrapolated differential cross section as a function of t1 and t2 enable extraction of the exponential slope parameters in several bins of the invariant mass of π+π− pairs. These parameters are sensitive to the size of the interaction region. [Figure not available: see fulltext.].

Published
2020

46. Measurement of D0-meson + hadron two-dimensional angular correlations in Au+Au collisions at sNN=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract

Open heavy-flavor hadrons provide unique probes of the medium produced in ultrarelativistic heavy-ion collisions. Due to their increased mass relative to light-flavor hadrons, long lifetime, and early production in hard-scattering interactions, they provide access to the full evolution of the partonic medium formed in heavy-ion collisions. This paper reports two-dimensional (2D) angular correlations between neutral D mesons and unidentified charged particles produced in minimum-bias Au+Au collisions at sNN=200GeV. D0 and D¯0 mesons are reconstructed via their weak decay to Kπ± using the Heavy Flavor Tracker in the Solenoidal Tracker at RHIC experiment. Correlations on relative pseudorapidity and azimuth (Δη,Δφ) are presented for peripheral, midcentral, and central collisions with D0 transverse momentum from 2-10GeV/c. Attention is focused on the 2D peaked correlation structure near the triggered D0 meson, the near-side (NS) peak, which serves as a proxy for a charm-quark-containing jet. The correlated NS yield of charged particles per D0 meson and the 2D widths of the NS peak increase significantly from peripheral to central collisions. These results are compared with similar correlations using unidentified charged particles, consisting primarily of light-flavor hadrons, at similar trigger particle momenta. Similar per-trigger yields and widths of the NS correlation peak are observed. The present results provide additional evidence that D0 mesons undergo significant interactions with the medium formed in heavy-ion collision and show, for the first time, significant centrality evolution of the NS 2D peak in the correlations of particles associated with a heavy-flavor hadron produced in these collisions.

Published
2020

47. First Measurement of Λc Baryon Production in Au+Au Collisions at sNN=200 GeV

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, Huang, T, and Huang, X

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, STAR Collaboration, nucl-ex, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

We report on the first measurement of the charmed baryon Λ_{c}^{±} production at midrapidity (|y|

Published
2020

48. Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T

Subjects
hep-ex, nucl-ex, nucl-th, Fluids & Plasmas, Mathematical Sciences, Physical Sciences
Abstract

According to the CPT theorem, which states that the combined operation of charge conjugation, parity transformation and time reversal must be conserved, particles and their antiparticles should have the same mass and lifetime but opposite charge and magnetic moment. Here, we test CPT symmetry in a nucleus containing a strange quark, more specifically in the hypertriton. This hypernucleus is the lightest one yet discovered and consists of a proton, a neutron and a Λ hyperon. With data recorded by the STAR detector1–3 at the Relativistic Heavy Ion Collider, we measure the Λ hyperon binding energy BΛ for the hypertriton, and find that it differs from the widely used value4 and from predictions5–8, where the hypertriton is treated as a weakly bound system. Our results place stringent constraints on the hyperon–nucleon interaction9,10 and have implications for understanding neutron star interiors, where strange matter may be present11. A precise comparison of the masses of the hypertriton and the antihypertriton allows us to test CPT symmetry in a nucleus with strangeness, and we observe no deviation from the expected exact symmetry.

Published
2020

49. Underlying event measurements in p+p collisions at s =200 GeV at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T

Subjects
nucl-ex, hep-ex
Abstract

Particle production sensitive to nonfactorizable and nonperturbative processes that contribute to the underlying event associated with a high transverse momentum (pT) jet in proton+proton collisions at s=200 GeV is studied with the STAR detector. Each event is divided into three regions based on the azimuthal angle with respect to the highest-pT jet direction: In the leading jet direction ("Toward"), opposite to the leading jet ("Away"), and perpendicular to the leading jet ("Transverse"). In the Transverse region, the average charged particle density is found to be between 0.4 and 0.6 and the mean transverse momentum,

Published
2020

50. Underlying event measurements in p+p collisions at s=200 GeV at RHIC

Author

Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, nucl-ex, hep-ex
Abstract

Particle production sensitive to nonfactorizable and nonperturbative processes that contribute to the underlying event associated with a high transverse momentum (pT) jet in proton+proton collisions at s=200 GeV is studied with the STAR detector. Each event is divided into three regions based on the azimuthal angle with respect to the highest-pT jet direction: In the leading jet direction ("Toward"), opposite to the leading jet ("Away"), and perpendicular to the leading jet ("Transverse"). In the Transverse region, the average charged particle density is found to be between 0.4 and 0.6 and the mean transverse momentum,

Published
2020

Catalog

Books, media, physical & digital resources
See catalog results