Statistical analysis of pQCD energy loss across system size, flavor, $$ \sqrt{s_{NN}} $$, and pT

A bstract We present suppression predictions from our pQCD-based energy loss model, which receives small system size corrections, for high- p T π , D and B meson R AB as a function of centrality, flavor, $$ \sqrt{s_{NN}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> , and p T from large to small collision systems at RHIC and LHC. A statistical analysis is used to constrain the effective strong coupling in our model to available high- p T suppression data from central heavy-ion collisions at RHIC and LHC, yielding good agreement with all available data. We estimate two important theoretical uncertainties in our model, stemming from: the transition between vacuum and hard thermal loop propagators in the collisional energy loss, and from the angular cutoff on the radiated gluon momentum. The model uncertainties lead to significant uncertainties in the extracted $$ {\alpha}_s^{\textrm{eff}.} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> <mml:mrow> <mml:mi>eff</mml:mi> <mml:mo>.</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> of 𝒪(30%), much larger than the uncertainties associated with the extraction procedure; however, the final uncertainty on the constrained R AB and on extrapolations of R AB to regions where it was not constrained, ≲ 20%, is significantly smaller than one might naively expect. We find the best fit extracted $$ {\alpha}_s^{\textrm{eff}.} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> <mml:mrow> <mml:mi>eff</mml:mi> <mml:mo>.</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> = $$ {0.41}_{-0.10}^{+0.14} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>0.41</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.14</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> at RHIC and $$ {\alpha}_s^{\textrm{eff}.} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> <mml:mrow> <mml:mi>eff</mml:mi> <mml:mo>.</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> = $$ {0.37}_{-0.08}^{+0.11} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>0.37</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.08</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.11</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> at LHC. When applying the statistical extraction of α s to different subsets of experimental data, we find, consistently, that the extracted α s remains relatively unchanged across heavy- and light-flavor final states and across central, semi-central, and peripheral collisions. We make predictions from our large-system-constrained model for small systems and find good agreement with the photon-normalized $$ {R}_{d\textrm{Au}}^{\pi^0} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>Au</mml:mi> </mml:mrow> <mml:msup> <mml:mi>π</mml:mi> <mml:mn>0</mml:mn> </mml:msup> </mml:msubsup> </mml:math> ≃ 0.75 in 0–5% centrality d + Au collisions by PHENIX. However, we find strong disagreement with the measured $$ {R}_{p\textrm{Pb}}^{h^{\pm }} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mrow> <mml:mi>p</mml:mi> <mml:mi>Pb</mml:mi> </mml:mrow> <mml:msup> <mml:mi>h</mml:mi> <mml:mo>±</mml:mo> </mml:msup> </mml:msubsup> </mml:math> ≳ 1 in 0–5% centrality p + Pb collisi