Tracking the baryon number with nuclear collisions

Abstract

Baryon quantum number is believed to be conserved since baryogenesis in the early Universe. While fractionally charged valence quarks are understood conventionally to each carry a baryon number of 1/3, the baryon junction, a non-perturbative Y-shaped topology of neutral gluons, has also been proposed as an alternative entity tracing the baryon number. Neither scenario has been verified experimentally. The STAR Collaboration reports measurements at mid-rapidity of baryon number ($\mathbf{B}$) over the electric charge number difference ($\mathbf{\Delta }\mathbf{Q}$) in isobar nuclear collisions, and the net-proton yield along rapidity in photonuclear collisions. A larger $\mathbf{B}/\Delta \mathbf{Q}$ 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.

References in corpus (31)

• Microscopic Models for Ultrarelativistic Heavy Ion Collisions
• Relativistic Hadron-Hadron Collisions in the Ultra-Relativistic Quantum Molecular Dynamics Model (UrQMD)
• Herwig 7.0 / Herwig++ 3.0 Release Note
• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• The STAR Time Projection Chamber: A Unique Tool for Studying High Multiplicity Events at RHIC
• Bulk Properties of the Medium Produced in Relativistic Heavy-Ion Collisions from the Beam Energy Scan Program
• String Formation Beyond Leading Colour
• Identified baryon and meson distributions at large transverse momenta from Au+Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• THERMUS -- A Thermal Model Package for ROOT
• Baryon Stopping and Charged Particle Distributions in Central Pb+Pb Collisions at 158 GeV per Nucleon
• Detailed Analysis of the Three Quark Potential in SU(3) Lattice QCD
• Three-Quark Potential in SU(3) Lattice QCD
• Beam energy dependence of (anti-)deuteron production in Au+Au collisions at RHIC
• The TOFp/pVPD Time of Flight System for STAR
• Gluon flux-tube distribution and linear confinement in baryons
• Antideuteron and antihelion production in root(s) = 130 GeV Au+Au collisions
• Nuclear stopping and rapidity loss in Au+Au collisions at sqrt{s_{NN}}=62.4 GeV
• Baryon Stopping and the Valence Quark Distribution at Small x
• The STAR Vertex Position Detector
• Baryonic Flux in Quenched and Two-Flavor Dynamical QCD after Abelian projection
• Flux Tubes of Two- and Three-Quark System in Full QCD
• Strange anti-particle to particle ratios at mid-rapidity in sqrt(s_NN)= 130 GeV Au+Au Collisions
• The string-junction picture of multiquark states: an update
• Search for baryon junctions in photonuclear processes and isobar collisions at RHIC
• Energy Dependence of the Breit-Wheeler process in Heavy-Ion Collisions and its Application to Nuclear Charge Radius Measurements
• Correlations of Baryon and Charge Stopping in Heavy Ion Collisions
• Lattice QCD Study for the Interquark Force in Three-Quark and Multi-Quark Systems
• Backward-Angle ($u$-channel) Production at an Electron-Ion Collider
• Buckyballs and gluon junction networks on the femtometer scale
• Beam energy dependence of net-hyperon yield and its implication on baryon transport mechanism
• Baryon correlations in Pythia