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System size dependence of associated yields in hadron-triggered jets
STAR Collaboration,Abelev, B.I.,Aggarwal, M.M.,Ahammed, Z.,Anderson, B.D.,Arkhipkin, D.,Averichev, G.S.,Balewski, J.,Barannikova, O.,Barnby, L.S.,Baudot, J.,Baumgart, S.,Beavis, D.R.,Bellwied, R.,Bene North-Holland Pub. Co 2010 Physics letters: B Vol.683 No.2
We present results on the system size dependence of high transverse momentum di-hadron correlations at s<SUB>NN</SUB>=200 GeV as measured by STAR at RHIC. Measurements in d+Au, Cu+Cu and Au+Au collisions reveal similar jet-like near-side correlation yields (correlations at small angular separation -Δφ∼0, Δη∼0) for all systems and centralities. Previous measurements have shown that the away-side (Δφ∼π) yield is suppressed in heavy-ion collisions. We present measurements of the away-side suppression as a function of transverse momentum and centrality in Cu+Cu and Au+Au collisions. The suppression is found to be similar in Cu+Cu and Au+Au collisions at a similar number of participants. The results are compared to theoretical calculations based on the parton quenching model and the modified fragmentation model. The observed differences between data and theory indicate that the correlated yields presented here will further constrain dynamic energy loss models and provide information about the dynamic density profile in heavy-ion collisions.
Abelev, B.,Adamczyk, L.,Adkins, J. K.,Agakishiev, G.,Aggarwal, M. M.,Ahammed, Z.,Alekseev, I.,Aparin, A.,Arkhipkin, D.,Aschenauer, E. C.,Ashraf, M. U.,Attri, A.,Averichev, G. S.,Bai, X.,Bairathi, V.,B American Physical Society 2016 Physical Review C Vol.94 No.1
<P>We present measurements of the near side of triggered di-hadron correlations using neutral strange baryons ( A, (A) over bar) and mesons (K-s(0)) at intermediate transverse momentum ( 3 < p(T) < 6 GeV/c) to look for possible flavor and baryon-meson dependence. This study is performed in d+Au, Cu+Cu, and Au+Au collisions at root S-NN = 200 GeV measured by the STAR experiment at RHIC. The near-side di-hadron correlation contains two structures, a peak which is narrow in azimuth and pseudorapidity consistent with correlations from jet fragmentation, and a correlation in azimuth which is broad in pseudorapidity. The particle composition of the jet-like correlation is determined using identified associated particles. The dependence of the conditional yield of the jet-like correlation on the trigger particle momentum, associated particle momentum, and centrality for correlations with unidentified trigger particles are presented. The neutral strange particle composition in jet-like correlations with unidentified charged particle triggers is not well described by PYTHIA. However, the yield of unidentified particles in jet-like correlations with neutral strange particle triggers is described reasonably well by the same model.</P>
Adamczyk, L.,Adkins, J. K.,Agakishiev, G.,Aggarwal, M. M.,Ahammed, Z.,Ajitanand, N. N.,Alekseev, I.,Anderson, D. M.,Aoyama, R.,Aparin, A.,Arkhipkin, D.,Aschenauer, E. C.,Ashraf, M. U.,Attri, A.,Averic American Physical Society 2017 Physical Review D Vol.95 No.7
<P>We report the first measurement of the longitudinal double-spin asymmetry A(LL) for midrapidity dijet production in polarized pp collisions at a center-of-mass energy of root s = 200 GeV. The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. A(LL) 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.</P>
Longitudinal spin transfer toΛandΛ¯hyperons in polarized proton-proton collisions ats=200 GeV
Abelev, B. I.,Aggarwal, M. M.,Ahammed, Z.,Alakhverdyants, A. V.,Anderson, B. D.,Arkhipkin, D.,Averichev, G. S.,Balewski, J.,Barannikova, O.,Barnby, L. S.,Baumgart, S.,Beavis, D. R.,Bellwied, R.,Benedo American Physical Society 2009 PHYSICAL REVIEW D - Vol.80 No.11