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34 results on '"Feng CJ"'

1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at GeV * * This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science, the U.S. National Science Foundation, the Ministry of Education and Science of the Russian Federation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the Higher Education Sprout Project by Ministry of Education at NCKU, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia

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, Physical Sciences, Quality Education, 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. Bulk properties of the system formed in Au+Au collisions at sNN=14.5 GeV at the BNL STAR detector

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, 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, Physical Sciences, nucl-ex, hep-ex, hep-ph, Nuclear and plasma physics
Abstract

We report systematic measurements of bulk properties of the system created in Au+Au collisions at sNN=14.5 GeV recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum spectra of π±, K±, and p(p) are studied at midrapidity (|y|

Published
2020

32. Bulk properties of the system formed in Au+Au collisions at sNN =14.5 GeV at the BNL STAR detector

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, 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, 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, hep-ph
Abstract

We report systematic measurements of bulk properties of the system created in Au+Au collisions at sNN=14.5 GeV recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum spectra of π±, K±, and p(p) are studied at midrapidity (|y|

Published
2020

33. Beam-energy dependence of identified two-particle angular correlations ins root s(NN)=7.7-200 GeV 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, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Sanchez, M Calderon de la Barca, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanad, M, Das, S, 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, B, Huang, HZ, Huang, SL, and Huang, T

Subjects
nucl-ex
Abstract

The two-particle angular correlation functions, $R_2$, of pions, kaons, andprotons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 14.5, 19.6, 27, 39,62.4, and 200 GeV were measured by the STAR experiment at RHIC. Thesecorrelations were measured for both like-sign and unlike-sign chargecombinations and versus the centrality. The correlations of pions and kaonsshow the expected near-side ({\it i.e.}, at small relative angles) peakresulting from short-range mechanisms. The amplitudes of these short-rangecorrelations decrease with increasing beam energy. However, the protoncorrelation functions exhibit strong anticorrelations in the near-side region.This behavior is observed for the first time in an A+A collision system. Theobserved anticorrelation is $p_{T}$-independent and decreases with increasingbeam energy and centrality. The experimental results are also compared to theMonte Carlo models UrQMD, Hijing, and AMPT.

Published
2020

34. Beam-energy dependence of identified two-particle angular correlations in sNN=7.7–200 GeV 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, Bassill, AJ, 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, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Das, S, 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, B, Huang, HZ, and Huang, SL

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

The two-particle angular correlation functions, $R_2$, of pions, kaons, andprotons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 14.5, 19.6, 27, 39,62.4, and 200 GeV were measured by the STAR experiment at RHIC. Thesecorrelations were measured for both like-sign and unlike-sign chargecombinations and versus the centrality. The correlations of pions and kaonsshow the expected near-side ({\it i.e.}, at small relative angles) peakresulting from short-range mechanisms. The amplitudes of these short-rangecorrelations decrease with increasing beam energy. However, the protoncorrelation functions exhibit strong anticorrelations in the near-side region.This behavior is observed for the first time in an A+A collision system. Theobserved anticorrelation is $p_{T}$-independent and decreases with increasingbeam energy and centrality. The experimental results are also compared to theMonte Carlo models UrQMD, Hijing, and AMPT.

Published
2020

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