# Quark Matter 2018

13-19 May 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## Particle production mechanisms studied via angular correlations of pions, kaons, protons, and lambdas in pp collisions at 7 TeV with ALICE

15 May 2018, 17:00
2h 40m
First floor and third floor (Palazzo del Casinò)

### First floor and third floor

#### Palazzo del Casinò

Poster Correlations and fluctuations

### Speaker

Malgorzata Anna Janik (Warsaw University of Technology (PL))

### Description

Two-particle correlations as a function of pseudorapidity difference, $\Delta\eta$, and azimuthal angle difference, $\Delta\varphi$, are used to study a wide range of physical phenomena and provide access to the underlying physics mechanisms of particle production in collisions of both protons and heavy ions. Examples include the collective behaviour of the QGP medium, jets, quantum statistics or Coulomb effects, conservation laws, and resonance decays.

In this contribution, we report measurements of the correlations of identified particles and their antiparticles ($\pi$, K, p, $\Lambda$) in pp collisions at $\sqrt{s}$ = 7 TeV for momenta up to 2.5 GeV/$c$. The analysis reveals significant differences in particle production between mesons and baryons. The correlation functions for mesons exhibit the expected peak dominated by effects of mini-jet fragmentation and are well reproduced by general purpose Monte Carlo generators. This is not the case for baryon pairs; results for baryons present a challenge to the contemporary models (PYTHIA, PHOJET) with simulations showing significant differences in respect to experimental data. Moreover, when both particles have the same baryon number (pp, $\bar{p}\bar{p}$, p$\Lambda$, $\bar{p}\bar{\Lambda}$, $\Lambda\Lambda$, $\bar{\Lambda}\bar{\Lambda}$) a near-side anti-correlation structure is observed instead of a peak. This unexpected observation is further interpreted in the context of baryon production mechanisms in the fragmentation process.

Collaboration ALICE Presenter name already specified Experiment

### Primary author

Malgorzata Anna Janik (Warsaw University of Technology (PL))

### Presentation Materials

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