# Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions

3-9 November 2019
Wanda Reign Wuhan Hotel
Asia/Shanghai timezone

## Study of $R_{2}(\Delta\eta, \Delta\varphi)$ and $P_{2}(\Delta\eta, \Delta\varphi)$ correlation functions in pp collisions at $\sqrt{\textit{s}} = 2.76$ TeV with the PYTHIA and HERWIG models

4 Nov 2019, 17:40
20m
Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

#### Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

Poster Presentation Small systems

### Speaker

Baidyanath Sahoo (IIT- Indian Institute of Technology (IN))

### Description

We study charge-independent (CI) and charge-dependent (CD) two-particle differential number correlation function, $R_{2}( \Delta\eta, \Delta\varphi)$, and transverse momentum correlation function, $P_{2}( \Delta\eta, \Delta\varphi)$, of unidentified ($h^{\pm}$) and identified (i.e. $\pi^{\pm}, K^{\pm}$ and $p\bar{p}$) charged particles produced in pp collisions at $\sqrt{\textit{s}}$ = 2.76 TeV using PYTHIA and HERWIG models. Correlators $R_{2}$ and $P_{2}$ calculated in the low-$\textit{p}_{\rm T}$ ($0.2 < \textit{p}_{\rm T} \leq 2.0~\rm{GeV}/\textit{c}$), intermediate-$\textit{p}_{\rm T}$ ($2.0 < \textit{p}_{\rm T} \leq 5.0 ~\rm{GeV}/\textit{c}$) and high-$\textit{p}_{\rm T}$ ($5.0 < \textit{p}_{\rm T} \leq 30.0 ~\rm{GeV}/\textit{c}$) transverse momentum ranges exhibit qualitatively similar near-side and away-side correlation structures but feature important quantitative differences. A narrower near-side peak is observed for $P_{2}$ as compared to $R_{2}$ along $\Delta \eta$, similar to recently published results from ALICE in the low-$\textit{p}_{\rm T}$ range for both CI and CD at any given centrality in A-A collisions. This difference is largely due to $\textit{p}_{\rm T}$ dependent angular ordering of hadrons produced inside jets. Comparing the two model predictions for the strength, shape and the width of both the correlators provides underlying particle production mechanism in pp collision. We conclude that future measurements of $R_{2}$ and $P_{2}$ correlators, particularly for high $\textit{p}_{\rm T}$ particles, would shed more light on the internal structure of jets and further the understanding the jet fragmentation function at low momentum fraction ($z$).

### Primary authors

Baidyanath Sahoo (IIT- Indian Institute of Technology (IN)) Basanta Kumar Nandi (IIT- Indian Institute of Technology (IN)) Prabhat Ranjan Pujahari (Indian Institute of Technology Madras (IN)) Sumit Basu (Wayne State University) Prof. Claude Andre Pruneau (Wayne State University (US))