Tracking the baryon number with nuclear collisions

Science 2026

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Authors: B.E. Aboona, J. Adam, L. Adamczyk, I. Aggarwal, M. M. Aggarwal, Z. Ahammed, A. K. Alshammri, E. C. Aschenauer, S. Aslam, J. Atchison, V. Bairathi, X. Bao
+88 more P. Barik, K. Barish, S. Behera, R. Bellwied, P. Bhagat, A. Bhasin, S. Bhatta, S. R. Bhosale, J. Bielcik, J. Bielcikova, J. D. Brandenburg, C. Broodo, X. Z. Cai, H. Caines, M. Calderon De La Barca Sanchez, D. Cebra, J. Ceska, I. Chakaberia, P. Chaloupka, Y. S. Chang, Z. Chang, A. Chatterjee, D. Chen, J. H. Chen, J. H. Chen, L. Chen, Q. Chen, W. Chen, Z. Chen, J. Cheng, Y. Cheng, W. Christie, X. Chu, S. Corey, H. J. Crawford, M. Csanad, G. Dale-Gau, A. Das, D. De Souza Lemos, I. M. Deppner, A. Deshpande, A. Dhamija, A. Dimri, P. Dixit, X. Dong, J. L. Drachenberg, E. Duckworth, J. C. Dunlop, Y. S. El-Feky, J. Engelage, G. Eppley, S. Esumi, O. Evdokimov, O. Eyser, B. Fan, Y. Fang, R. Fatemi, S. Fazio, H. Feng, Y. Feng, E. Finch, Y. Fisyak, F. A. Flor, B. Fu, C. Fu, T. Fu, C. A. Gagliardi, T. Galatyuk, T. Gao, Y. Gao, G. Garcia, F. Geurts, A. Gibson, A. Giri, K. Gopal, X. Gou, D. Grosnick, A. Gu, J. Gu, A. Gupta, W. Guryn, A. Hamed, R. J. Hamilton, J. Han, X. Han, S. Harabasz, M. D. Harasty, J. W. Harris
DOI: 10.1126/science.ads5962
Cited by: 3
References: 56

Abstract

Baryon quantum number is found to be conserved since baryogenesis in the early Universe. Conventionally, each fractionally charged valence quark is understood to carry one-third of a baryon number. An alternative hypothesis posits that baryon number is instead carried by a baryon junction—a nonperturbative, Y-shaped gluonic configuration. Neither scenario has been verified experimentally. The STAR Collaboration reports measurements at mid-rapidity of baryon number ( B ) over the electric charge number difference (∆ Q ) in isobar nuclear collisions, and the net-proton yield along rapidity in photonuclear collisions. A larger B /∆ Q ratio and less asymmetric net-proton yield are observed than predicted from models assigning baryon number to valence quarks. These findings, corroborated by previous measurements in Au+Au collisions, disfavor the valence quark picture.

Fields of Study & Subjects

High-Energy Particle Collisions Research Quantum Chromodynamics and Particle Interactions Pulsars and Gravitational Waves Research

Publication details

Journal / source
Science
Publisher
American Association for the Advancement of Science (AAAS)
Volume
393
Issue
6812
Pages
727–731
Publication date
13 August 2026
Language
EN