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Disentangling Centrality Bias and Final-State Effects in the Production of High-𝑝 𝑇 Neutral Pions Using Direct Photon in 𝑑+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV

Abdulameer, N. J. [Debrecen University; HUN-REN ATOMKI]·Acharya, U. [Georgia State University]·Aidala, C. [University of Michigan]·Akiba, Y. [RIKEN Nishina Center for Accelerator-Based Science; Brookhaven National Laboratory]·Alfred, M. [Howard University]·Aoki, K. [High Energy Accelerator Research Organization]·Apadula, N. [Iowa State University]·Ayuso, C. [University of Michigan]·Babintsev, V. [Institute for High Energy Physics]·Barish, K. N. [University of California-Riverside]·Bathe, S. [City University of New York; Brookhaven National Laboratory]·Bazilevsky, A. [Brookhaven National Laboratory]·Belmont, R. [University of Colorado; University of North Carolina at Greensboro]·Berdnikov, A. [Saint Petersburg State Polytechnic University]·Berdnikov, Y. [Saint Petersburg State Polytechnic University]·Bichon, L. [Vanderbilt University]·Blankenship, B. [Vanderbilt University]·Blau, D. S. [National Research Center “Kurchatov Institute”; National Research Nuclear University]·Boer, M. [Los Alamos National Laboratory]·Bok, J. S. [New Mexico State University]·Borisov, V. [Saint Petersburg State Polytechnic University]·Brooks, M. L. [Los Alamos National Laboratory]·Bryslawskyj, J. [City University of New York; University of California-Riverside]·Bumazhnov, V. [Institute for High Energy Physics]·Butler, C. [Georgia State University]·Campbell, S. [Columbia University; Nevis Laboratories]·Canoa Roman, V. [Stony Brook University]·Chiu, M. [Brookhaven National Laboratory]·Connors, M. [Georgia State University; Brookhaven National Laboratory]·Corliss, R. [Stony Brook University]·Corrales Morales, Y. [Los Alamos National Laboratory]·Csanád, M. [Eötvös Loránd University]·Csörgő, T. [Institute of Technology; Institute for Particle and Nuclear Physics]·Liu, L. D. [Peking University]·Danley, T. W. [Ohio University]·Daugherity, M. S. [Abilene Christian University]·David, G. [Brookhaven National Laboratory; Stony Brook University]·Dean, C. T. [Los Alamos National Laboratory]·DeBlasio, K. [University of New Mexico]·Dehmelt, K. [Stony Brook University]·Denisov, A. [Institute for High Energy Physics]·Deshpande, A. [Brookhaven National Laboratory; Stony Brook University]·Desmond, E. J. [Brookhaven National Laboratory]·Doomra, V. [Stony Brook University]·Do, J. H. [Yonsei University]·Drees, A. [Stony Brook University]·Drees, K. A. [Brookhaven National Laboratory]·Dumancic, M. [Weizmann Institute]·Durham, J. M. [Los Alamos National Laboratory]·Durum, A. [Institute for High Energy Physics]·Elder, T. [Georgia State University]·Enokizono, A. [RIKEN Nishina Center for Accelerator-Based Science; Rikkyo University]·Esha, R. [Stony Brook University]·Fadem, B. [Muhlenberg College]·Fan, W. [Stony Brook University]·Feege, N. [Stony Brook University]·Finger, M. [Charles University]·Firak, D. [Debrecen University; Stony Brook University]·Fitzgerald, D. [University of Michigan]·Fokin, S. L. [National Research Center “Kurchatov Institute”]·Frantz, J. E. [Ohio University]·Franz, A. [Brookhaven National Laboratory]·Frawley, A. D. [Florida State University]·Fukuda, Y. [University of Tsukuba]·Gal, C. [Stony Brook University]·Garg, P. [Banaras Hindu University; Stony Brook University]·Ge, H. [Stony Brook University]·Giles, M. [Stony Brook University]·Goto, Y. [RIKEN Nishina Center for Accelerator-Based Science; Brookhaven National Laboratory]·Grau, N. [Augustana University]·Greene, S. V. [Vanderbilt University]·Gunji, T. [University of Tokyo]·Hachiya, T. [Nara Women’s University; Brookhaven National Laboratory]·Haggerty, J. S. [Brookhaven National Laboratory]·Hahn, K. I. [Ewha Womans University]·Han, S. Y. [Ewha Womans University; Korea University]·Harvey, M. [Texas Southern University]·Hasegawa, S. [Japan Atomic Energy Agency]·Haseler, T. O. S. [Georgia State University]·Hemmick, T. K. [Stony Brook University]·He, X. [Georgia State University]·Hill, K. [University of Colorado]·Hodges, A. [Georgia State University; University of Illinois at Urbana-Champaign]·Homma, K. [Hiroshima University]·Hong, B. [Korea University]·Hoshino, T. [Hiroshima University]·Hotvedt, N. [Iowa State University]·Huang, J. [Brookhaven National Laboratory]·Imrek, J. [Debrecen University]·Inaba, M. [University of Tsukuba]·Isenhower, D. [Abilene Christian University]·Ito, Y. [Nara Women’s University]·Ivanishchev, D. [Petersburg Nuclear Physics Institute]·Jacak, B. V. [Stony Brook University]·Ji, Z. [Stony Brook University]·Johnson, B. M. [Brookhaven National Laboratory; Georgia State University] (ORCID:0000000338504493)·Jorjadze, V. [Stony Brook University]·Jouan, D. [Université Paris-Saclay]·Jumper, D. S. [University of Illinois at Urbana-Champaign]·Kang, J. H. [Yonsei University]
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Abstract

Here, PHENIX presents a simultaneous measurement of the production of direct 𝛾 and 𝜋 0 in 𝑑 + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV over a 𝑝 𝑇 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, 𝑅$^{𝜋^0}_{dAu,EXP}$, 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, 𝑅$^{𝜋^0}_{dAu,EXP}$ is consistent with the MB value within 5% uncertainty. This result confirms that the previously observed enhancement of high-𝑝 𝑇 𝜋 0 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, 𝑅$^{𝜋^0}_{dAu,EXP}$ is suppressed by 20% relative to the MB value with a significance of 4.5⁢𝜎, which may be due to final-state effects. This suppression corresponds to a 𝑝 𝑇 shift of 𝛿⁢𝑝 𝑇 = 0.213 ± 0.055 Gev/𝑐 at 9 Gev/𝑐.

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BibTeXRIS

Abdulameer, N. J. [Debrecen University; HUN-REN ATOMKI], Acharya, U. [Georgia State University], Aidala, C. [University of Michigan], Akiba, Y. [RIKEN Nishina Center for Accelerator-Based Science; Brookhaven National Laboratory], Alfred, M. [Howard University], Aoki, K. [High Energy Accelerator Research Organization], Apadula, N. [Iowa State University], Ayuso, C. [University of Michigan], Babintsev, V. [Institute for High Energy Physics], Barish, K. N. [University of California-Riverside], Bathe, S. [City University of New York; Brookhaven National Laboratory], Bazilevsky, A. [Brookhaven National Laboratory], Belmont, R. [University of Colorado; University of North Carolina at Greensboro], Berdnikov, A. [Saint Petersburg State Polytechnic University], Berdnikov, Y. [Saint Petersburg State Polytechnic University], Bichon, L. [Vanderbilt University], Blankenship, B. [Vanderbilt University], Blau, D. S. [National Research Center “Kurchatov Institute”; National Research Nuclear University], Boer, M. [Los Alamos National Laboratory], Bok, J. S. [New Mexico State University], Borisov, V. [Saint Petersburg State Polytechnic University], Brooks, M. L. [Los Alamos National Laboratory], Bryslawskyj, J. [City University of New York; University of California-Riverside], Bumazhnov, V. [Institute for High Energy Physics], Butler, C. [Georgia State University], Campbell, S. [Columbia University; Nevis Laboratories], Canoa Roman, V. [Stony Brook University], Chiu, M. [Brookhaven National Laboratory], Connors, M. [Georgia State University; Brookhaven National Laboratory], Corliss, R. [Stony Brook University], Corrales Morales, Y. [Los Alamos National Laboratory], Csanád, M. [Eötvös Loránd University], Csörgő, T. [Institute of Technology; Institute for Particle and Nuclear Physics], Liu, L. D. [Peking University], Danley, T. W. [Ohio University], Daugherity, M. S. [Abilene Christian University], David, G. [Brookhaven National Laboratory; Stony Brook University], Dean, C. T. [Los Alamos National Laboratory], DeBlasio, K. [University of New Mexico], Dehmelt, K. [Stony Brook University], Denisov, A. [Institute for High Energy Physics], Deshpande, A. [Brookhaven National Laboratory; Stony Brook University], Desmond, E. J. [Brookhaven National Laboratory], Doomra, V. [Stony Brook University], Do, J. H. [Yonsei University], Drees, A. [Stony Brook University], Drees, K. A. [Brookhaven National Laboratory], Dumancic, M. [Weizmann Institute], Durham, J. M. [Los Alamos National Laboratory], Durum, A. [Institute for High Energy Physics], Elder, T. [Georgia State University], Enokizono, A. [RIKEN Nishina Center for Accelerator-Based Science; Rikkyo University], Esha, R. [Stony Brook University], Fadem, B. [Muhlenberg College], Fan, W. [Stony Brook University], Feege, N. [Stony Brook University], Finger, M. [Charles University], Firak, D. [Debrecen University; Stony Brook University], Fitzgerald, D. [University of Michigan], Fokin, S. L. [National Research Center “Kurchatov Institute”], Frantz, J. E. [Ohio University], Franz, A. [Brookhaven National Laboratory], Frawley, A. D. [Florida State University], Fukuda, Y. [University of Tsukuba], Gal, C. [Stony Brook University], Garg, P. [Banaras Hindu University; Stony Brook University], Ge, H. [Stony Brook University], Giles, M. [Stony Brook University], Goto, Y. [RIKEN Nishina Center for Accelerator-Based Science; Brookhaven National Laboratory], Grau, N. [Augustana University], Greene, S. V. [Vanderbilt University], Gunji, T. [University of Tokyo], Hachiya, T. [Nara Women’s University; Brookhaven National Laboratory], Haggerty, J. S. [Brookhaven National Laboratory], Hahn, K. I. [Ewha Womans University], Han, S. Y. [Ewha Womans University; Korea University], Harvey, M. [Texas Southern University], Hasegawa, S. [Japan Atomic Energy Agency], Haseler, T. O. S. [Georgia State University], Hemmick, T. K. [Stony Brook University], He, X. [Georgia State University], Hill, K. [University of Colorado], Hodges, A. [Georgia State University; University of Illinois at Urbana-Champaign], Homma, K. [Hiroshima University], Hong, B. [Korea University], Hoshino, T. [Hiroshima University], Hotvedt, N. [Iowa State University], Huang, J. [Brookhaven National Laboratory], Imrek, J. [Debrecen University], Inaba, M. [University of Tsukuba], Isenhower, D. [Abilene Christian University], Ito, Y. [Nara Women’s University], Ivanishchev, D. [Petersburg Nuclear Physics Institute], Jacak, B. V. [Stony Brook University], Ji, Z. [Stony Brook University], Johnson, B. M. [Brookhaven National Laboratory; Georgia State University] (ORCID:0000000338504493), Jorjadze, V. [Stony Brook University], Jouan, D. [Université Paris-Saclay], Jumper, D. S. [University of Illinois at Urbana-Champaign], Kang, J. H. [Yonsei University]. 2025-01-15. Disentangling Centrality Bias and Final-State Effects in the Production of High-𝑝 𝑇 Neutral Pions Using Direct Photon in 𝑑+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV. https://doi.org/10.1103/physrevlett.134.022302

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