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 - 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 - Dumancic, M.
AU - Milov, A.
AU - Tserruya, I.
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 - http://www.scopus.com/inward/record.url?scp=85215390612&partnerID=8YFLogxK
U2 - https://doi.org/10.1103/PhysRevLett.134.022302
DO - https://doi.org/10.1103/PhysRevLett.134.022302
M3 - مقالة
SN - 0031-9007
VL - 134
JO - Physical review letters
JF - Physical review letters
IS - 2
M1 - 022302
ER -