MPI dependence of the near- and away-side pT spectra for 5 TeV pp, p-Pb and Pb-Pb collisions with the ALICE detector at the LHC

Jun 2, 2020, 7:30 AM
1h 20m


Poster Presentation Jets and High Momentum Hadrons Poster session


Sushanta Tripathy (Universidad Nacional Autonoma (MX))


The similarities between pp, p-A and A-A collisions have not been fully understood. One issue when comparing e.g. transverse momentum ($p_{\rm T}$) distributions for different colliding systems at similar mid-rapidity multiplicity, is that selection biases and autocorrelations may play different roles. Recently, the use of the correlation between relatively high-$p_{\rm T}$ tracks ($p_{\rm T}^{\rm leading}>5$ GeV/$c$) and hadrons at lower momenta ($0.5< p_{\rm T}^{\rm associated}<5$ GeV/$c$) has been proposed in order to introduce a new multiplicity estimator. Based on distinct regions defined by $\Delta\phi=\phi_{\rm leading}-\phi_{\rm associated}$, the so-called transverse region, $\pi/3<|\Delta\phi|<2\pi/3$, can be used to build a multiplicity estimator ($N_{\rm T}$) which by definition does not contain the leading and sub-leading jet peaks. In pp collisions simulated with QCD-inspired event generators like PYTHIA, $N_{\rm T}$ is sensitive to Multiple Partonic Interactions (MPI).

This MPI-motivated analysis has been successfully applied to ALICE $\sqrt{s}=13$ TeV pp data; we now extend the study to bigger systems like p-Pb and Pb-Pb collisions. In this work, the $p_{\rm T}$ spectra in the near ($|\Delta\phi|<\pi/3$), away ($|\Delta\phi|>2\pi/3$) and transverse regions will be presented a function of $N_{\rm T}$. Results include measurements for pp, p-Pb and Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. Comparisons among the near and away side $p_{\rm T}$ spectra, at the same $N_{\rm T}$ and $\sqrt{s_{\rm NN}}$, will be shown. The role of auto-correlations and potential effects of MPI in p-Pb and Pb-Pb collisions will be discussed. Comparisons with existing QCD-inspired event generators will be shown.

Contribution type Contributed Talk
Track Jets and High Momentum Hadrons
Collaboration (if applicable) ALICE

Primary author

Presentation materials