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186 results on '"Bouchet, J."'

1. Measurements of dihadron correlations relative to the event plane in Au+Au collisions at GeV

Author: Agakishiev, H, Aggarwal, MM, Ahammed, Z, Alakhverdyants, AV, Alekseev, I, Alford, J, Anderson, BD, Anson, CD, Arkhipkin, D, Averichev, GS, Balewski, J, Beavis, DR, Behera, NK, Bellwied, R, Betancourt, MJ, Betts, RR, Bhasin, A, Bhati, AK, Bichsel, H, Bielcik, J, Bielcikova, J, Biritz, B, Bland, LC, Borowski, W, Bouchet, J, Braidot, E, Brandin, AV, Bridgeman, A, Brovko, SG, Bruna, E, Bueltmann, S, Bunzarov, I, Burton, TP, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Cendejas, R, Cervantes, MC, Chajecki, Z, Chaloupka, P, Chattopadhyay, S, Chen, HF, Chen, JH, Chen, JY, Chen, L, Cheng, J, Cherney, M, Chikanian, A, Choi, KE, Christie, W, Chung, P, Codrington, MJM, Corliss, R, Cramer, JG, Crawford, HJ, Dash, S, Leyva, A Davila, De Silva, LC, Debbe, RR, Dedovich, TG, Derevschikov, AA, de Souza, R Derradi, Didenko, L, Djawotho, P, Dogra, SM, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elnimr, M, Engelage, J, Eppley, G, Estienne, M, Eun, L, Evdokimov, O, Fatemi, R, Fedorisin, J, Feng, A, Fersch, RG, Filip, P, Finch, E, Fine, V, Fisyak, Y, Gagliardi, CA, Gangadharan, DR, Geromitsos, A, Geurts, F, Ghosh, P, Gorbunov, YN, Gordon, A, Grebenyuk, O, Grosnick, D, Guertin, SM, Gupta, A, Guryn, W, Haag, B, Hajkova, O, and Hamed, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, relativistic heavy ion collisions, dihadron correlations, jet-medium interactions, anisotropic flow background, event plane, nucl-ex, nucl-th, NSD-Relativistic Nuclear Collisions, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Dihadron azimuthal correlations containing a high transverse momentum (pT) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to p+p and d+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20%-60%) Au+Au collisions at GeV as a function of the trigger particle's azimuthal angle relative to the event plane, . The azimuthal correlation is studied as a function of both the trigger and associated particle . The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with , with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity correlation) appears to drop with increasing while the jet-like component remains approximately constant. The correlation functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the -dependence of the ridge or the away-side double-peak structure. The dropping ridge with could be attributed to a -dependent elliptic anisotropy; however, the physics mechanism of the ridge remains an open question. Even with a -dependent elliptic flow, the away-side correlation structure is robust. These results, with extensive systematic studies of the dihadron correlations as a function of , trigger and associated particle , and the pseudo-rapidity range , should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.
Published: 2021

2. Measurements of dihadron correlations relative to the event plane in Au+Au collisions at √sNN= 200 GeV

Author: Agakishiev, H, Aggarwal, MM, Ahammed, Z, Alakhverdyants, AV, Alekseev, I, Alford, J, Anderson, BD, Anson, CD, Arkhipkin, D, Averichev, GS, Balewski, J, Beavis, DR, Behera, NK, Bellwied, R, Betancourt, MJ, Betts, RR, Bhasin, A, Bhati, AK, Bichsel, H, Bielcik, J, Bielcikova, J, Biritz, B, Bland, LC, Borowski, W, Bouchet, J, Braidot, E, Brandin, AV, Bridgeman, A, Brovko, SG, Bruna, E, Bueltmann, S, Bunzarov, I, Burton, TP, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Cendejas, R, Cervantes, MC, Chajecki, Z, Chaloupka, P, Chattopadhyay, S, Chen, HF, Chen, JH, Chen, JY, Chen, L, Cheng, J, Cherney, M, Chikanian, A, Choi, KE, Christie, W, Chung, P, Codrington, MJM, Corliss, R, Cramer, JG, Crawford, HJ, Dash, S, Davila Leyva, A, De Silva, LC, Debbe, RR, Dedovich, TG, Derevschikov, AA, Derradi De Souza, R, Didenko, L, Djawotho, P, Dogra, SM, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elnimr, M, Engelage, J, Eppley, G, Estienne, M, Eun, L, Evdokimov, O, Fatemi, R, Fedorisin, J, Feng, A, Fersch, RG, Filip, P, Finch, E, Fine, V, Fisyak, Y, Gagliardi, CA, Gangadharan, DR, Geromitsos, A, Geurts, F, Ghosh, P, Gorbunov, YN, Gordon, A, Grebenyuk, O, Grosnick, D, Guertin, SM, Gupta, A, Guryn, W, Haag, B, Hajkova, O, and Hamed, A
Subjects: relativistic heavy ion collisions, dihadron correlations, jet-medium interactions, anisotropic flow background, event plane, nucl-ex, nucl-th, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Dihadron azimuthal correlations containing a high transverse momentum (pT) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to p+p and d+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20%-60%) Au+Au collisions at GeV as a function of the trigger particle's azimuthal angle relative to the event plane, . The azimuthal correlation is studied as a function of both the trigger and associated particle . The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with , with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity correlation) appears to drop with increasing while the jet-like component remains approximately constant. The correlation functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the -dependence of the ridge or the away-side double-peak structure. The dropping ridge with could be attributed to a -dependent elliptic anisotropy; however, the physics mechanism of the ridge remains an open question. Even with a -dependent elliptic flow, the away-side correlation structure is robust. These results, with extensive systematic studies of the dihadron correlations as a function of , trigger and associated particle , and the pseudo-rapidity range , should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.
Published: 2021

3. Constraining the initial conditions and temperature dependent viscosity with three-particle correlations in Au+Au collisions

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, Heppelmann, S, and Hirsch, A
Subjects: nucl-ex, nucl-th, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: We present three-particle mixed-harmonic correlations 〈cos⁡(mϕa+nϕb−(m+n)ϕc)〉 for harmonics m,n=1−3 for charged particles in sNN=200 GeV Au+Au collisions at RHIC. These measurements provide information on the three-dimensional structure of the initial collision zone and are important for constraining models of a subsequent low-viscosity quark–gluon plasma expansion phase. We investigate correlations between the first, second and third harmonics predicted as a consequence of fluctuations in the initial state. The dependence of the correlations on the pseudorapidity separation between particles show hints of a breaking of longitudinal invariance. We compare our results to a number of state-of-the art hydrodynamic calculations with different initial states and temperature dependent viscosities. These measurements provide important steps towards constraining the temperature dependent viscosity and longitudinal structure of the initial state at RHIC.
Published: 2019

4. Collision energy dependence of moments of net-kaon multiplicity distributions at RHIC

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, and Harlenderova, A
Subjects: nucl-ex, hep-ex, hep-ph, nucl-th, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Fluctuations of conserved quantities such as baryon number, charge, and strangeness are sensitive to the correlation length of the hot and dense matter created in relativistic heavy-ion collisions and can be used to search for the QCD critical point. We report the first measurements of the moments of net-kaon multiplicity distributions in Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV. The collision centrality and energy dependence of the mean (M), variance (σ2), skewness (S), and kurtosis (κ) for net-kaon multiplicity distributions as well as the ratio σ2/M and the products Sσ and κσ2 are presented. Comparisons are made with Poisson and negative binomial baseline calculations as well as with UrQMD, a transport model (UrQMD) that does not include effects from the QCD critical point. Within current uncertainties, the net-kaon cumulant ratios appear to be monotonic as a function of collision energy.
Published: 2018

5. Harmonic decomposition of three-particle azimuthal correlations at energies available at the BNL Relativistic Heavy Ion Collider

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Sanchez, M Calderon de la Barca, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, Heppelmann, S, and Hirsch, A
Subjects: nucl-ex, nucl-th
Abstract: We present measurements of three-particle correlations for various harmonicsin Au+Au collisions at energies ranging from $\sqrt{s_{{\rm NN}}}=7.7$ to 200GeV using the STAR detector. The quantity$\langle\cos(m\phi_1+n\phi_2-(m+n)\phi_3)\rangle$ is evaluated as a function of$\sqrt{s_{{\rm NN}}}$, collision centrality, transverse momentum, $p_T$,pseudo-rapidity difference, $\Delta\eta$, and harmonics ($m$ and $n$). Thesedata provide detailed information on global event properties like thethree-dimensional structure of the initial overlap region, the expansiondynamics of the matter produced in the collisions, and the transport propertiesof the medium. A strong dependence on $\Delta\eta$ is observed for mostharmonic combinations consistent with breaking of longitudinal boostinvariance. Data reveal changes with energy in the two-particle correlationfunctions relative to the second-harmonic event-plane and provide ways toconstrain models of heavy-ion collisions over a wide range of collisionenergies.
Published: 2018

6. Correlation measurements between flow harmonics in Au+Au collisions at RHIC

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: Collectivity, Correlation, Shear viscosity, nucl-ex, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Flow harmonics (vn) in the Fourier expansion of the azimuthal distribution of particles are widely used to quantify the anisotropy in particle emission in high-energy heavy-ion collisions. The symmetric cumulants, SC(m,n), are used to measure the correlations between different orders of flow harmonics. These correlations are used to constrain the initial conditions and the transport properties of the medium in theoretical models. In this Letter, we present the first measurements of the four-particle symmetric cumulants in Au+Au collisions at sNN=39 and 200 GeV from data collected by the STAR experiment at RHIC. We observe that v2 and v3 are anti-correlated in all centrality intervals with similar correlation strengths from 39 GeV Au+Au to 2.76 TeV Pb+Pb (measured by the ALICE experiment). The v2–v4 correlation seems to be stronger at 39 GeV than at higher collision energies. The initial-stage anti-correlations between second and third order eccentricities are sufficient to describe the measured correlations between v2 and v3. The best description of v2–v4 correlations at sNN=200GeV is obtained with inclusion of the system's nonlinear response to initial eccentricities accompanied by the viscous effect with η/s>0.08. Theoretical calculations using different initial conditions, equations of state and viscous coefficients need to be further explored to extract η/s of the medium created at RHIC.
Published: 2018

7. Beam Energy Dependence of Jet-Quenching Effects in Au+Au Collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, and Harlenderova, A
Subjects: Affordable and Clean Energy, STAR Collaboration, nucl-ex, hep-ex, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract: We report measurements of the nuclear modification factor R_{CP} for charged hadrons as well as identified π^{+(-)}, K^{+(-)}, and p(p[over ¯]) for Au+Au collision energies of sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-p_{T} net suppression in central collisions at 62.4 GeV for charged hadrons which evolves smoothly to a large net enhancement at lower energies. This trend is driven by the evolution of the pion spectra but is also very similar for the kaon spectra. While the magnitude of the proton R_{CP} at high p_{T} does depend on the collision energy, neither the proton nor the antiproton R_{CP} at high p_{T} exhibit net suppression at any energy. A study of how the binary collision-scaled high-p_{T} yield evolves with centrality reveals a nonmonotonic shape that is consistent with the idea that jet quenching is increasing faster than the combined phenomena that lead to enhancement.
Published: 2018

8. Measurement of the H Λ3 lifetime in Au+Au collisions at the BNL Relativistic Heavy Ion Collider

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Alford, J, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
Subjects: nucl-ex
Abstract: An improved measurement of the HΛ3 lifetime is presented. In this paper, the mesonic decay modes HΛ3→He3 + π- and HΛ3→d+p+π- are used to reconstruct the HΛ3 from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC). A minimum χ2 estimation is used to determine the lifetime of τ=142-21+24(stat.)±29(syst.) ps. This lifetime is about 50% shorter than the lifetime τ=263±2 ps of a free Λ, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.(He3+π-)/(B.R.(He3+π-)+B.R.(d+p+π-))=0.32±0.05(stat.)±0.08(syst.). Our ratio result favors the assignment J(HΛ3)=12 over J(HΛ3)=32. These measurements will help to constrain models of hyperon-baryon interactions.
Published: 2018

9. Transverse spin-dependent azimuthal correlations of charged pion pairs measured in p↑ + p collisions at s=500 GeV

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, Heppelmann, S, and Herrmann, N
Subjects: Transversity, Di-hadron correlations, Interference fragmentation function, hep-ex, nucl-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The transversity distribution, which describes transversely polarized quarks in transversely polarized nucleons, is a fundamental component of the spin structure of the nucleon, and is only loosely constrained by global fits to existing semi-inclusive deep inelastic scattering (SIDIS) data. In transversely polarized p↑+p collisions it can be accessed using transverse polarization dependent fragmentation functions which give rise to azimuthal correlations between the polarization of the struck parton and the final state scalar mesons. This letter reports on spin dependent di-hadron correlations measured by the STAR experiment. The new dataset corresponds to 25 pb−1 integrated luminosity of p↑+p collisions at s=500 GeV, an increase of more than a factor of ten compared to our previous measurement at s=200 GeV. Non-zero asymmetries sensitive to transversity are observed at a Q2 of several hundred GeV and are found to be consistent with the former measurement and a model calculation. We expect that these data will enable an extraction of transversity with comparable precision to current SIDIS datasets but at much higher momentum transfers where subleading effects are suppressed.
Published: 2018

10. Measurement of the HΛ3 lifetime in Au+Au collisions at the BNL Relativistic Heavy Ion Collider

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Alford, J, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
Subjects: nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: An improved measurement of the HΛ3 lifetime is presented. In this paper, the mesonic decay modes HΛ3→He3 + π- and HΛ3→d+p+π- are used to reconstruct the HΛ3 from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC). A minimum χ2 estimation is used to determine the lifetime of τ=142-21+24(stat.)±29(syst.) ps. This lifetime is about 50% shorter than the lifetime τ=263±2 ps of a free Λ, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.(He3+π-)/(B.R.(He3+π-)+B.R.(d+p+π-))=0.32±0.05(stat.)±0.08(syst.). Our ratio result favors the assignment J(HΛ3)=12 over J(HΛ3)=32. These measurements will help to constrain models of hyperon-baryon interactions.
Published: 2018

11. Transverse spin-dependent azimuthal correlations of charged pion pairs measured in p ↑ + p collisions at s = 500 GeV

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, Heppelmann, S, and Herrmann, N
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Quantum Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Transversity, Di-hadron correlations, Interference fragmentation function, hep-ex, nucl-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Mathematical sciences, Physical sciences
Abstract: The transversity distribution, which describes transversely polarized quarks in transversely polarized nucleons, is a fundamental component of the spin structure of the nucleon, and is only loosely constrained by global fits to existing semi-inclusive deep inelastic scattering (SIDIS) data. In transversely polarized p↑+p collisions it can be accessed using transverse polarization dependent fragmentation functions which give rise to azimuthal correlations between the polarization of the struck parton and the final state scalar mesons. This letter reports on spin dependent di-hadron correlations measured by the STAR experiment. The new dataset corresponds to 25 pb−1 integrated luminosity of p↑+p collisions at s=500 GeV, an increase of more than a factor of ten compared to our previous measurement at s=200 GeV. Non-zero asymmetries sensitive to transversity are observed at a Q2 of several hundred GeV and are found to be consistent with the former measurement and a model calculation. We expect that these data will enable an extraction of transversity with comparable precision to current SIDIS datasets but at much higher momentum transfers where subleading effects are suppressed.
Published: 2018

12. Beam-Energy Dependence of Directed Flow of Λ, Λ¯, K±, Ks0, and ϕ in Au+Au Collisions

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, and Harris, JW
Subjects: Nuclear and Plasma Physics, Physical Sciences, STAR Collaboration, hep-ex, nucl-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: Rapidity-odd directed-flow measurements at midrapidity are presented for Λ, Λ[over ¯], K^{±}, K_{s}^{0}, and ϕ at sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV in Au+Au collisions recorded by the Solenoidal Tracker detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available to constrain models with differing prescriptions for the equation of state of quantum chromodynamics. Results show good sensitivity for testing a picture where flow is assumed to be imposed before hadron formation and the observed particles are assumed to form via coalescence of constituent quarks. The pattern of departure from a coalescence-inspired sum rule can be a valuable new tool for probing the collision dynamics.
Published: 2018

13. Azimuthal transverse single-spin asymmetries of inclusive jets and charged pions within jets from polarized-proton collisions at s=500 GeV

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, hep-ex, nucl-ex
Abstract: We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet+π± production at midrapidity from transversely polarized proton-proton collisions at s=500 GeV. The data were collected in 2011 with the STAR detector sampled from 23 pb-1 integrated luminosity with an average beam polarization of 53%. Asymmetries are reported for jets with transverse momenta 6
Published: 2018

14. Beam-Energy Dependence of Directed Flow of Λ, Λ[over ¯], K^{±}, K_{s}^{0}, and ϕ in Au+Au Collisions.

Author: Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, and Harris, JW
Subjects: STAR Collaboration, hep-ex, nucl-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: Rapidity-odd directed-flow measurements at midrapidity are presented for Λ, Λ[over ¯], K^{±}, K_{s}^{0}, and ϕ at sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV in Au+Au collisions recorded by the Solenoidal Tracker detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available to constrain models with differing prescriptions for the equation of state of quantum chromodynamics. Results show good sensitivity for testing a picture where flow is assumed to be imposed before hadron formation and the observed particles are assumed to form via coalescence of constituent quarks. The pattern of departure from a coalescence-inspired sum rule can be a valuable new tool for probing the collision dynamics.
Published: 2018

15. Azimuthal transverse single-spin asymmetries of inclusive jets and charged pions within jets from polarized-proton collisions at s = 500 GeV

Author: AdamczyK, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, BielciK, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Dedovich, TG, Deng, J, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, FisyaK, Y, Flores, CE, Fujita, J, FuleK, L, Gagliardi, CA, Geurts, F, Gibson, A, Girard, M, GrosnicK, D, Gunarathne, DS, Guo, Y, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: hep-ex, nucl-ex
Abstract: We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet+π± production at midrapidity from transversely polarized proton-proton collisions at s=500 GeV. The data were collected in 2011 with the STAR detector sampled from 23 pb-1 integrated luminosity with an average beam polarization of 53%. Asymmetries are reported for jets with transverse momenta 6
Published: 2018

16. Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: nucl-ex
Abstract: We present measurements of bulk properties of the matter produced in Au+Au collisions at sNN=7.7,11.5,19.6,27, and 39 GeV using identified hadrons (π±, K±, p, and p) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y|
Published: 2017

17. Energy dependence of J/ψ production in Au + Au collisions at sNN=39,62.4 and 200GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
Subjects: hep-ex, nucl-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The inclusive J/ψ transverse momentum spectra and nuclear modification factors are reported at mid-rapidity (|y|
Published: 2017

18. Dijet imbalance measurements in Au+Au and pp collisions at sqrt[s_{NN}]=200 GeV at STAR.

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, 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, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, and Hoffmann, GW
Subjects: STAR Collaboration, nucl-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: We report the first dijet transverse momentum asymmetry measurements from Au+Au and pp collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly higher momentum imbalance in heavy-ion collisions than in the pp reference. When reexamined with correlated soft particles included, we observe that these dijets then exhibit a unique new feature-momentum balance is restored to that observed in pp for a jet resolution parameter of R=0.4, while rebalancing is not attained with a smaller value of R=0.2.
Published: 2017

19. Energy dependence of J/ψ production in Au+Au collisions at sNN=39,62.4 and 200GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Affordable and Clean Energy, hep-ex, nucl-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, Mathematical sciences, Physical sciences
Abstract: The inclusive J/ψ transverse momentum spectra and nuclear modification factors are reported at mid-rapidity (|y|
Published: 2017

20. Global Λ hyperon polarization in nuclear collisions

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Sanchez, M Calderon De la Barca, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, STAR Collaboration, nucl-ex, General Science & Technology
Abstract: The extreme energy densities generated by ultra-relativistic collisions between heavy atomic nuclei produce a state of matter that behaves surprisingly like a fluid, with exceptionally high temperature and low viscosity. Non-central collisions have angular momenta of the order of 1,000ћ, and the resulting fluid may have a strong vortical structure that must be understood to describe the fluid properly. The vortical structure is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. However, no experimental indications of fluid vorticity in heavy ion collisions have yet been found. Since vorticity represents a local rotational structure of the fluid, spin-orbit coupling can lead to preferential orientation of particle spins along the direction of rotation. Here we present measurements of an alignment between the global angular momentum of a non-central collision and the spin of emitted particles (in this case the collision occurs between gold nuclei and produces Λ baryons), revealing that the fluid produced in heavy ion collisions is the most vortical system so far observed. (At high energies, this fluid is a quark-gluon plasma.) We find that Λ and hyperons show a positive polarization of the order of a few per cent, consistent with some hydrodynamic predictions. (A hyperon is a particle composed of three quarks, at least one of which is a strange quark; the remainder are up and down quarks, found in protons and neutrons.) A previous measurement that reported a null result, that is, zero polarization, at higher collision energies is seen to be consistent with the trend of our observations, though with larger statistical uncertainties. These data provide experimental access to the vortical structure of the nearly ideal liquid created in a heavy ion collision and should prove valuable in the development of hydrodynamic models that quantitatively connect observations to the theory of the strong force.
Published: 2017

21. Direct virtual photon production in Au+Au collisions at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
Subjects: nucl-ex, hep-ex, hep-ph, nucl-th, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: We report the direct virtual photon invariant yields in the transverse momentum ranges 16 GeV/c the production follows TAA scaling. Model calculations with contributions from thermal radiation and initial hard parton scattering are consistent within uncertainties with the direct virtual photon invariant yield.
Published: 2017

22. Measurement of D0 Azimuthal Anisotropy at Midrapidity in Au+Au Collisions at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, and He, L
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: We report the first measurement of the elliptic anisotropy (v_{2}) of the charm meson D^{0} at midrapidity (|y|
Published: 2017

23. Measurement of the cross section and longitudinal double-spin asymmetry for dijet production in polarized pp collisions at s=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, and Harris, JW
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, hep-ex, nucl-ex
Abstract: We report the first measurement of the longitudinal double-spin asymmetry ALL for midrapidity dijet production in polarized pp collisions at a center-of-mass energy of s=200 GeV. The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. ALL results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. The measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of Bjorken-x>0.05.
Published: 2017

24. Measurement of the cross section and longitudinal double-spin asymmetry for dijet production in polarized pp collisions at s =200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, and Harris, JW
Subjects: hep-ex, nucl-ex
Abstract: We report the first measurement of the longitudinal double-spin asymmetry ALL for midrapidity dijet production in polarized pp collisions at a center-of-mass energy of s=200 GeV. The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. ALL results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. The measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of Bjorken-x>0.05.
Published: 2017

25. Elliptic flow of electrons from heavy-flavor hadron decays in Au + Au collisions at √sNN =200, 62.4, and 39 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: hep-ex, nucl-ex
Abstract: We present measurements of elliptic flow (v2) of electrons from the decays of heavy-flavor hadrons (eHF) by the STAR experiment. For Au+Au collisions at sNN=200 GeV we report v2, for transverse momentum (pT) between 0.2 and 7 GeV/c, using three methods: the event plane method (v2{EP}), two-particle correlations (v2{2}), and four-particle correlations (v2{4}). For Au+Au collisions at sNN=62.4 and 39 GeV we report v2{2} for pT
Published: 2017

26. Elliptic flow of electrons from heavy-flavor hadron decays in Au + Au collisions at sNN=200, 62.4, and 39 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, Harris, JW, He, L, and Heppelmann, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, nucl-ex, Nuclear and plasma physics
Abstract: We present measurements of elliptic flow (v2) of electrons from the decays of heavy-flavor hadrons (eHF) by the STAR experiment. For Au+Au collisions at sNN=200 GeV we report v2, for transverse momentum (pT) between 0.2 and 7 GeV/c, using three methods: the event plane method (v2{EP}), two-particle correlations (v2{2}), and four-particle correlations (v2{4}). For Au+Au collisions at sNN=62.4 and 39 GeV we report v2{2} for pT
Published: 2017

27. Coherent diffractive photoproduction of $ρ^{0}$ mesons on gold nuclei at RHIC

Author: Collaboration, STAR, Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Ajitanand, NN, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Brown, D, Bunzarov, I, Butterworth, J, Caines, H, Sánchez, M Calderón de la Barca, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Silva, LC De, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Federicova, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fujita, J, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Harlenderova, A, and Harris, JW
Subjects: nucl-ex, hep-ex
Abstract: The STAR Collaboration reports on the photoproduction of $\pi^+\pi^-$ pairsin gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair.These pion pairs are produced when a nearly-real photon emitted by one ionscatters from the other ion. We fit the $\pi^+\pi^-$ invariant mass spectrum with a combination of $\rho$and $\omega$ resonances and a direct $\pi^+\pi^-$ continuum. This is the firstobservation of the $\omega$ in ultra-peripheral collisions, and the firstmeasurement of $\rho-\omega$ interference at energies where photoproduction isdominated by Pomeron exchange. The $\omega$ amplitude is consistent with themeasured $\gamma p\rightarrow \omega p$ cross section, a classical Glaubercalculation and the $\omega\rightarrow\pi^+\pi^-$ branching ratio. The $\omega$phase angle is similar to that observed at much lower energies, showing thatthe $\rho-\omega$ phase difference does not depend significantly on photonenergy. The $\rho^0$ differential cross section $d\sigma/dt$ exhibits a cleardiffraction pattern, compatible with scattering from a gold nucleus, with 2minima visible. The positions of the diffractive minima agree better with thepredictions of a quantum Glauber calculation that does not include nuclearshadowing than with a calculation that does include shadowing.
Published: 2017

28. Charge-Dependent Directed Flow in Cu+Au Collisions at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, and Huang, B
Subjects: STAR Collaboration, nucl-ex, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract: We present the first measurement of charge-dependent directed flow in Cu+Au collisions at sqrt[s_{NN}]=200 GeV. The results are presented as a function of the particle transverse momentum and pseudorapidity for different centralities. A finite difference between the directed flow of positive and negative charged particles is observed that qualitatively agrees with the expectations from the effects of the initial strong electric field between two colliding ions with different nuclear charges. The measured difference in directed flow is much smaller than that obtained from the parton-hadron-string-dynamics model, which suggests that most of the electric charges, i.e., quarks and antiquarks, have not yet been created during the lifetime of the strong electric field, which is of the order of, or less than, 1 fm/c.
Published: 2017

29. ϒ production in U + U collisions at sNN =193 GeV measured with the STAR experiment

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, HZ, and Huang, B
Subjects: nucl-ex, hep-ex
Abstract: We present a measurement of the inclusive production of ϒ mesons in U+U collisions at sNN=193 GeV at midrapidity (|y|
Published: 2016

30. Υ production in U + U collisions at sNN=193 GeV measured with the STAR experiment

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, HZ, and Huang, B
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex, Nuclear and plasma physics
Abstract: We present a measurement of the inclusive production of ϒ mesons in U+U collisions at sNN=193 GeV at midrapidity (|y|
Published: 2016

31. Jet-like correlations with direct-photon and neutral-pion triggers at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, B, Huang, X, and Huang, HZ
Subjects: nucl-ex, hep-ex, hep-ph, nucl-th, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Azimuthal correlations of charged hadrons with direct-photon (γdir) and neutral-pion (π0) trigger particles are analyzed in central Au+Au and minimum-bias p+p collisions at sNN=200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p+p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γdir trigger is independent of the transverse momentum of the trigger particle (pTtrig), whereas the suppression is smaller at low transverse momentum of the associated charged hadrons (pTassoc). Within uncertainty, similar levels of suppression are observed for γdir and π0 triggers as a function of zT (≡pTassoc/pTtrig). The results are compared with energy-loss-inspired theoretical model predictions. Our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy.
Published: 2016

32. Near-side azimuthal and pseudorapidity correlations using neutral strange baryons and mesons in d+ Au, Cu + Cu, and Au + Au collisions at sNN =200 GeV

Author: Abelev, B, Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barnby, LS, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bombara, M, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Gaillard, L, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, and Huang, T
Subjects: nucl-ex
Abstract: We present measurements of the near side of triggered di-hadron correlations using neutral strange baryons (Λ,Λ) and mesons (KS0) at intermediate transverse momentum (3 < pT
Published: 2016

33. Near-side azimuthal and pseudorapidity correlations using neutral strange baryons and mesons in d+Au, Cu + Cu, and Au + Au collisions at sNN=200 GeV

Author: Abelev, B, Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Barnby, LS, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bombara, M, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Gaillard, L, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, and Huang, T
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract: We present measurements of the near side of triggered di-hadron correlations using neutral strange baryons (Λ,Λ) and mesons (KS0) at intermediate transverse momentum (3 < pT
Published: 2016

34. J/ψ production at low transverse momentum in p+p and d + Au collisions at sNN =200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, X, Huang, B, Huang, HZ, Huck, P, and Humanic, TJ
Subjects: nucl-ex
Abstract: We report on the measurement of J/ψ production in the dielectron channel at midrapidity (|y|
Published: 2016

35. J/ψ production at low transverse momentum in p+p and d + Au collisions at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, X, Huang, B, Huang, HZ, Huck, P, and Humanic, TJ
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract: We report on the measurement of J/ψ production in the dielectron channel at midrapidity (|y|
Published: 2016

36. Measurement of the Transverse Single-Spin Asymmetry in p↑+p→W±/Z0 at RHIC

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, X, Huang, HZ, Huang, B, Huang, T, and Huck, P
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Quantum Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, STAR Collaboration, nucl-ex, hep-ex, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at sqrt[s]=500 GeV by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD.
Published: 2016

37. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, X, Huang, B, Huang, HZ, Huck, P, and Humanic, TJ
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: We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from sqrt[s_{NN}]=7.7 to 200 GeV. The third harmonic v_{3}^{2}{2}=⟨cos3(ϕ_{1}-ϕ_{2})⟩, where ϕ_{1}-ϕ_{2} is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη=η_{1}-η_{2}. Nonzero v_{3}^{2}{2} is directly related to the previously observed large-Δη narrow-Δϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v_{3}^{2}{2} persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v_{3}^{2}{2} is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v_{3}^{2}{2} for central collisions shows a minimum near sqrt[s_{NN}]=20 GeV.
Published: 2016

38. Probing parton dynamics of QCD matter with Ω and φ production

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, X, Huang, B, Huang, HZ, Huck, P, and Humanic, TJ
Subjects: nucl-ex
Abstract: We present measurements of Ω and φ production at midrapidity from Au+Au collisions at nucleon-nucleon center-of-mass energies sNN=7.7, 11.5, 19.6, 27, and 39 GeV by the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). Motivated by the coalescence formation mechanism for these strange hadrons, we study the ratios of N(Ω-+Ω#x0002B;)/[2N(φ)]. These ratios as a function of transverse momentum pT fall on a consistent trend at high collision energies, but start to show deviations in peripheral collisions at sNN=19.6, 27, and 39 GeV, and in central collisions at 11.5 GeV in the intermediate pT region of 2.4-3.6 GeV/c. We further evaluate empirically the strange quark pT distributions at hadronization by studying the Ω/φ ratios scaled by the number of constituent quarks (NCQ). The NCQ-scaled Ω/φ ratios show a suppression of strange quark production in central collisions at 11.5 GeV compared to sNN≥19.6 GeV. The shapes of the presumably thermal strange quark distributions in 0-60% most central collisions at 7.7 GeV show significant deviations from those in 0-10% most central collisions at higher energies. These features suggest that there is likely a change of the underlying strange quark dynamics in the transition from quark matter to hadronic matter at collision energies below 19.6 GeV.
Published: 2016

39. Centrality and Transverse Momentum Dependence of Elliptic Flow of Multistrange Hadrons and ϕ Meson in Au+Au Collisions at sNN=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, X, Huang, B, Huang, HZ, Huck, P, Humanic, TJ, Igo, G, and Jacobs, WW
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, STAR Collaboration, nucl-ex, hep-ex, hep-ph, nucl-th, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: We present high precision measurements of elliptic flow near midrapidity (|y|
Published: 2016

40. Centrality and Transverse Momentum Dependence of Elliptic Flow of Multistrange Hadrons and ϕ Meson in Au+Au Collisions at √[sNN]=200 GeV.

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, X, Huang, B, Huang, HZ, Huck, P, Humanic, TJ, Igo, G, and Jacobs, WW
Subjects: STAR Collaboration, nucl-ex, hep-ex, hep-ph, nucl-th, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: We present high precision measurements of elliptic flow near midrapidity (|y|
Published: 2016

41. Measurement of elliptic flow of light nuclei at $\sqrt{s_{NN}}$ = 200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at RHIC

Author: Collaboration, STAR, Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Attri, A, Averichev, GS, Bai, X, Bairathi, V, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Sánchez, M Calderón de la Barca, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chang, Z, Chatterjee, A, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, Silva, LC De, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Ruzza, B di, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Horvat, S, Huang, T, Huang, HZ, Huang, X, and Huang, B
Subjects: nucl-ex, hep-ex, hep-ph
Abstract: We present measurements of 2$^{nd}$ order azimuthal anisotropy ($v_{2}$) atmid-rapidity $(|y|
Published: 2016

42. Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at sNN =7.7-62.4 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bai, X, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, D, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Chisman, O, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, HZ, Huang, B, Huang, X, and Huck, P
Subjects: nucl-ex
Abstract: Elliptic flow (v2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at sNN=7.7-62.4 GeV are presented for three centrality classes. The centrality dependence and the data at sNN=14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative v2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.
Published: 2016

43. Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at sNN=7.7–62.4 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bai, X, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, D, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Chisman, O, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, HZ, Huang, B, Huang, X, and Huck, P
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, nucl-ex, Nuclear and plasma physics
Abstract: Elliptic flow (v2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at sNN=7.7-62.4 GeV are presented for three centrality classes. The centrality dependence and the data at sNN=14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative v2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.
Published: 2016

44. Di-hadron correlations with identified leading hadrons in 200 GeV Au+Au and d+Au collisions at STAR

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bai, X, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, D, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, X, Chen, JH, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, T, Huang, B, Huang, HZ, Huang, X, and Huck, P
Subjects: nucl-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au. +. Au and minimum-bias d. +. Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au. +. Au data with respect to the d. +. Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.
Published: 2015

45. Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in p↑+p at s=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Burton, TP, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, B, Huang, X, Huang, HZ, Huck, P, Humanic, TJ, and Igo, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Quantum Physics, Physical Sciences, STAR Collaboration, hep-ex, nucl-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p^{↑}+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η>0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions.
Published: 2015

46. Azimuthal Anisotropy in U+U and Au+Au Collisions at RHIC

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Burton, TP, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, HZ, Huang, B, Huang, X, Huck, P, Humanic, TJ, and Igo, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, STAR Collaboration, nucl-ex, nucl-th, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v_{2}{2} and v_{2}{4}, for charged hadrons from U+U collisions at sqrt[s_{NN}]=193 GeV and Au+Au collisions at sqrt[s_{NN}]=200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v_{2}{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. We also show that v_{2} vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.
Published: 2015

47. Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au+Au collisions at √sNN=19.6 and 200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Burton, TP, Butterworth, J, Caines, H, Calder'on de la Barca S'anchez, M, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Codrington, MJM, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, HZ, Huang, X, Huang, B, Huck, P, Humanic, TJ, and Igo, G
Subjects: hep-ex, nucl-ex, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity |yee|
Published: 2015

48. Measurement of interaction between antiprotons

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Bairathi, V, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Caines, H, Sanchez, M Calderon de la Barca, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Z, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, A, Gupta, S, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, B, Huang, HZ, Huang, X, Huck, P, and Humanic, TJ
Subjects: Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, STAR Collaboration, nucl-ex, hep-ex, nucl-th, General Science & Technology
Abstract: One of the primary goals of nuclear physics is to understand the force between nucleons, which is a necessary step for understanding the structure of nuclei and how nuclei interact with each other. Rutherford discovered the atomic nucleus in 1911, and the large body of knowledge about the nuclear force that has since been acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, little is known directly about the nuclear force between antinucleons. Here, we study antiproton pair correlations among data collected by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), where gold ions are collided with a centre-of-mass energy of 200 gigaelectronvolts per nucleon pair. Antiprotons are abundantly produced in such collisions, thus making it feasible to study details of the antiproton-antiproton interaction. By applying a technique similar to Hanbury Brown and Twiss intensity interferometry, we show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: the scattering length and the effective range of the interaction. Our measured parameters are consistent within errors with the corresponding values for proton-proton interactions. Our results provide direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, and so are fundamental to understanding the structure of more-complex antinuclei and their properties.
Published: 2015

49. Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au+Au collisions at sNN=19.6 and 200 GeV

Author: Collaboration, STAR, Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Banerjee, A, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Bouchet, J, Brandin, AV, Bunzarov, I, Burton, TP, Butterworth, J, Caines, H, de la Barca S'anchez, M Calder'on, Campbell, JM, Cebra, D, Cervantes, MC, Chakaberia, I, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Codrington, MJM, Contin, G, Crawford, HJ, Das, S, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, di Ruzza, B, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Eppley, G, Esha, R, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Filip, P, Fisyak, Y, Flores, CE, Fulek, L, Gagliardi, CA, Garand, D, Geurts, F, Gibson, A, Girard, M, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, Gupta, S, Gupta, A, Guryn, W, Hamad, A, Hamed, A, Haque, R, Harris, JW, He, L, Heppelmann, S, Hirsch, A, Hoffmann, GW, Hofman, DJ, Horvat, S, Huang, HZ, Huang, X, Huang, B, Huck, P, and Humanic, TJ
Subjects: hep-ex, nucl-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity |yee|
Published: 2015

50. Precision Measurement of the Longitudinal Double-Spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at s=200 GeV

Author: Adamczyk, L, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Alford, J, Anson, CD, Aparin, A, Arkhipkin, D, Aschenauer, EC, Averichev, GS, Banerjee, A, Beavis, DR, Bellwied, R, Bhasin, A, Bhati, AK, Bhattarai, P, Bichsel, H, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Borowski, W, Bouchet, J, Brandin, AV, Brovko, SG, Bültmann, S, Bunzarov, I, Burton, TP, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Campbell, JM, Cebra, D, Cendejas, R, Cervantes, MC, Chaloupka, P, Chang, Z, Chattopadhyay, S, Chen, HF, Chen, JH, Chen, L, Cheng, J, Cherney, M, Chikanian, A, Christie, W, Chwastowski, J, Codrington, MJM, Contin, G, Cramer, JG, Crawford, HJ, Cudd, AB, Cui, X, Das, S, Davila Leyva, A, De Silva, LC, Debbe, RR, Dedovich, TG, Deng, J, Derevschikov, AA, Derradi de Souza, R, Dhamija, S, di Ruzza, B, Didenko, L, Dilks, C, Ding, F, Djawotho, P, Dong, X, Drachenberg, JL, Draper, JE, Du, CM, Dunkelberger, LE, Dunlop, JC, Efimov, LG, Engelage, J, Engle, KS, Eppley, G, Eun, L, Evdokimov, O, Eyser, O, Fatemi, R, Fazio, S, Fedorisin, J, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Gagliardi, CA, Gangadharan, DR, Garand, D, Geurts, F, Gibson, A, Girard, M, Gliske, S, Greiner, L, Grosnick, D, Gunarathne, DS, Guo, Y, and Gupta, A
Subjects: STAR Collaboration, hep-ex, nucl-ex, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract: We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, A_{LL}, in polarized pp collisions at center-of-mass energy sqrt[s]=200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. The measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x>0.05.
Published: 2015

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