TY - JOUR
T1 - Disentangling Centrality Bias and Final-State Effects in the Production of High- pT Neutral Pions Using Direct Photon in d+Au Collisions at sNN =200 GeV
AU - (PHENIX Collaboration)
AU - Abdulameer, N. J.
AU - Acharya, U.
AU - Aidala, C.
AU - Akiba, Y.
AU - Alfred, M.
AU - Aoki, K.
AU - Apadula, N.
AU - Ayuso, C.
AU - Babintsev, V.
AU - Barish, K. N.
AU - Bathe, S.
AU - Bazilevsky, A.
AU - Belmont, R.
AU - Berdnikov, A.
AU - Berdnikov, Y.
AU - Bichon, L.
AU - Blankenship, B.
AU - Blau, D. S.
AU - Boer, M.
AU - Bok, J. S.
AU - Borisov, V.
AU - Brooks, M. L.
AU - Bryslawskyj, J.
AU - Bumazhnov, V.
AU - Butler, C.
AU - Campbell, S.
AU - Canoa Roman, V.
AU - Chiu, M.
AU - Connors, M.
AU - Corliss, R.
AU - Corrales Morales, Y.
AU - Csanád, M.
AU - Csörgo, T.
AU - Liu, L. D.
AU - Danley, T. W.
AU - Daugherity, M. S.
AU - David, G.
AU - Dean, C. T.
AU - Deblasio, K.
AU - Dehmelt, K.
AU - Denisov, A.
AU - Deshpande, A.
AU - Desmond, E. J.
AU - Doomra, V.
AU - Do, J. H.
AU - Drees, A.
AU - Drees, K. A.
AU - Dumancic, M.
AU - Esha, R.
AU - Hemmick, T. K.
N1 - Publisher Copyright:
© 2025 American Physical Society.
PY - 2025/1/17
Y1 - 2025/1/17
N2 - PHENIX presents a simultaneous measurement of the production of direct γ and π0 in d+Au collisions at sNN=200 GeV over a pT range of 7.5 to 18 GeV/c for different event samples selected by event activity, i.e., charged-particle multiplicity detected at forward rapidity. Direct-photon yields are used to empirically estimate the contribution of hard-scattering processes in the different event samples. Using this estimate, the average nuclear-modification factor, RdAu,EXPπ0, is 0.925±0.023(stat)±0.15(scale), consistent with unity for minimum-bias (MB) d+Au collisions. For event classes with low and moderate event activity, RdAu,EXPπ0 is consistent with the MB value within 5% uncertainty. This result confirms that the previously observed enhancement of high-pT π0 production found in small-system collisions with low event activity is a result of a bias in interpreting event activity within the Glauber framework. In contrast, for the top 5% of events with the highest event activity, RdAu,EXPπ0 is suppressed by 20% relative to the MB value with a significance of 4.5σ, which may be due to final-state effects. This suppression corresponds to a pT shift of δpT=0.213±0.055 Gev/c at 9 Gev/c.
AB - PHENIX presents a simultaneous measurement of the production of direct γ and π0 in d+Au collisions at sNN=200 GeV over a pT range of 7.5 to 18 GeV/c for different event samples selected by event activity, i.e., charged-particle multiplicity detected at forward rapidity. Direct-photon yields are used to empirically estimate the contribution of hard-scattering processes in the different event samples. Using this estimate, the average nuclear-modification factor, RdAu,EXPπ0, is 0.925±0.023(stat)±0.15(scale), consistent with unity for minimum-bias (MB) d+Au collisions. For event classes with low and moderate event activity, RdAu,EXPπ0 is consistent with the MB value within 5% uncertainty. This result confirms that the previously observed enhancement of high-pT π0 production found in small-system collisions with low event activity is a result of a bias in interpreting event activity within the Glauber framework. In contrast, for the top 5% of events with the highest event activity, RdAu,EXPπ0 is suppressed by 20% relative to the MB value with a significance of 4.5σ, which may be due to final-state effects. This suppression corresponds to a pT shift of δpT=0.213±0.055 Gev/c at 9 Gev/c.
UR - https://www.scopus.com/pages/publications/85215390612
U2 - 10.1103/PhysRevLett.134.022302
DO - 10.1103/PhysRevLett.134.022302
M3 - Article
C2 - 39913799
AN - SCOPUS:85215390612
SN - 0031-9007
VL - 134
JO - Physical Review Letters
JF - Physical Review Letters
IS - 2
M1 - 022302
ER -