"Jet momentum fraction ($z^{\mathrm{ch}}_{||}$) 13 TeV" of "Measurement of the production of charm jets tagged with ${\rm D^0}$ mesons in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV"

The measurement of the production of charm jets, identified by the presence of a $\mathrm{D^0}$ meson in the jet constituents, is presented in proton--proton collisions at centre-of-mass energies of $\sqrt{s}=5.02$ and $13$ TeV with the ALICE detector at the CERN LHC.The $\mathrm{D^0}$ mesons were reconstructed from their hadronic decay $\mathrm{D^0}\rightarrow\mathrm{K}^{-}\mathrm{\pi}^{0}$ and the respective charge conjugate. Jets were reconstructed from $\mathrm{D^0}$-meson candidates and charged particles using the anti-$k_\text{T}$ algorithm, in the jet transverse momentum range $5 < p_{\mathrm{T,ch\ jet}}< 50$ GeV/$c$, pseudorapidity $|\eta_{\mathrm{ch\ jet}}| < 0.9-R$, and with the jet resolution parameters $R = 0.2$, $0.4$, $0.6$. The distribution of the jet momentum fraction carried by a $\mathrm{D^0}$ meson along the jet axis ($z^{\mathrm{ch}}_{||}$) was measured in the range $0.4< z^{\mathrm{ch}}_{||} <1.0$ in four ranges of the jet transverse momentum.Comparisons of results for different collision energies and jet resolution parameters are also presented. The measurements are compared to predictions from Monte Carlo event generators based on leading-order and next-to-leading-order perturbative quantum chromodynamics calculations. A generally good description of the main features of the data is obtained in spite of a few discrepancies at low $p_{\mathrm{T,ch\ jet}}$. Measurements were also done for $R=0.3$ at $\sqrt{s}=5.02$ TeV and are shown along with their comparisons to theoretical predictions in an appendix to this paper.

本文报道了在欧洲核子研究中心（CERN）大型强子对撞机（LHC）上利用ALICE探测器（ALICE detector），在质心系能量√s=5.02和13 TeV的质子-质子碰撞中，对通过喷注内部组分存在D⁰介子（D⁰ meson）来识别的粲喷注（charm jets）产额的测量结果。研究中通过强子衰变道D⁰→K⁻π⁰及其对应电荷共轭过程重建D⁰介子，并利用anti-k_T算法（anti-k_T algorithm），在喷注横向动量范围5 < p_T,ch jet < 50 GeV/c、赝快度范围|η_ch jet| < 0.9−R以及喷注分辨参数R取0.2、0.4、0.6的条件下，从D⁰介子候选体与带电粒子中重建喷注。本文还测量了D⁰介子沿喷注轴携带的喷注动量份额z^ch_||的分布，该测量在喷注横向动量的四个区间内覆盖0.4 < z^ch_|| < 1.0的范围。此外，本文对不同碰撞能量与喷注分辨参数下的结果进行了对比，并将本次测量结果与基于领头阶（leading-order）和次领头阶（next-to-leading-order）微扰量子色动力学（perturbative quantum chromodynamics）计算的蒙特卡洛事件产生器（Monte Carlo event generators）的理论预言进行了比对；尽管在低喷注横向动量p_T,ch jet区域存在少量偏差，但整体上理论预言能够较好地描述实验数据的主要特征。本文还在√s=5.02 TeV的质心系能量下针对喷注分辨参数R=0.3的情况开展了测量，并将该测量结果与理论预言的比对内容置于本文附录中。