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Theoretical Particle Physics


Baryon anomaly in heavy-ion collisions and colour correlations in QGP


Baryon anomaly in heavy-ion collisions and colour correlations in QGP

Research areas:

Física Teórica de Partículas



Type of Publication:

Technical Report


  • Eugeny Levin
  • Gustaw Matulewicz
  • Mikhail G. Ryskin
  • Karel Safarik




A baryon anomaly - an increased baryon-to-meson production ratio at intermediate p_T in heavyion collisions when compared to pp collisions - is observed at RHIC and the LHC. This effect is usually explained by recombination of constituent quarks during QGP hadronization, or as a consequence of a strong radial flow developed during the heavy-ion collision. In this contribution, an additional mechanism to favour baryon over meson production is proposed: when hadrons are formed in the recombination of nearby quarks and antiquarks, only colour-singlet combinations can be chosen. Hadron formation, in particular the probability to create baryons or mesons, depends on the distribution of colour charges among quarks. If the distribution is random - a reasonable assumption for Quark-Gluon Plasma (QGP) - the baryon-to-meson ratio is nearly twice higher than in the situation where quark colours are pre-arranged to obtain a white hadron in the combination of nearest quarks and antiquarks. The correlation of colour charges in the QGP also influences the distance over which recombination occurs. A study of the dependence of the baryon-to-meson ratio on the size of the colour correlation domain is presented.