Inconsistencies in, and short pathlength correction to, in  and collisions

Coleridge Faraday; Antonia Grindrod; W. A. Horowitz

doi:10.1140/epjc/s10052-023-12234-y

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 1060
https://doi.org/10.1140/epjc/s10052-023-12234-y

Regular Article - Theoretical Physics

Inconsistencies in, and short pathlength correction to, $R_{AA} (p_{T})$ $R_{AA}(p_T)$ in $A + A$ $\textrm{A}+\textrm{A}$ and $p + A$ $\textrm{p} + \textrm{A}$ collisions

Coleridge Faraday^a, Antonia Grindrod and W. A. Horowitz

Department of Physics, University of Cape Town, Private Bag X3, 7701, Rondebosch, South Africa

^a frdcol002@myuct.ac.za

Received: 29 May 2023
Accepted: 6 November 2023
Published online: 20 November 2023

Abstract

We present the first leading hadron suppression predictions in $Pb + Pb$ $\textrm{Pb}+\textrm{Pb}$ and $p + Pb$ $\textrm{p}+\textrm{Pb}$ collisions from a convolved radiative and collisional energy loss model in which partons propagate through a realistic background and in which the radiative energy loss receives a short pathlength correction. We find that the short pathlength correction is small for D and B meson $R_{AA} (p_{T})$ $R_{AA}(p_T)$ in both $Pb + Pb$ $\textrm{Pb}+\textrm{Pb}$ and $p + Pb$ $\textrm{p}+\textrm{Pb}$ collisions. However the short pathlength correction leads to a surprisingly large reduction in suppression for $π$ $\pi$ mesons in $p + Pb$ $\textrm{p}+\textrm{Pb}$ and even $Pb + Pb$ $\textrm{Pb}+\textrm{Pb}$ collisions. We systematically check the consistency of the assumptions used in the radiative energy loss derivation-such as collinearity, softness, and large formation time-with the final numerical model. While collinearity and softness are self-consistently satisfied in the final numerics, we find that the large formation time approximation breaks down at modest to high momenta $p_{T} ≳ 30 GeV$ $p_T \gtrsim 30~\textrm{GeV}$ . We find that both the size of the small pathlength correction to $R_{AA} (p_{T})$ $R_{AA}(p_T)$ and the $p_{T}$ $$p_T$$ at which the large formation time assumption breaks down are acutely sensitive to the chosen distribution of scattering centers in the plasma.

© The Author(s) 2023

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