"Cross-section ratios $\sigma(13$ TeV$)/\sigma(5.02$ 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.本工作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，针对质心系能量√s=5.02 TeV和13 TeV的质子-质子碰撞开展的粲喷注产生测量：粲喷注通过其组成成分中存在D⁰介子（D⁰ meson）来识别。D⁰介子通过其强衰变道D⁰→K⁻π⁰及其对应的电荷共轭过程完成重建。本研究利用反$k_ ext{T}$算法（anti-$k_ ext{T}$ algorithm），从D⁰介子候选体与带电粒子中重建喷注，分析的喷注满足以下条件：带电喷注横向动量范围为$5 < p_{mathrm{T,ch jet}} < 50$ GeV/$c$，赝快度$|eta_{mathrm{ch jet}}| < 0.9-R$，且喷注分辨参数$R$取0.2、0.4、0.6。本研究测量了D⁰介子沿喷注轴携带的喷注动量分数$z^{mathrm{ch}}_{||}$的分布，在四个带电喷注横向动量区间内，该分布的测量区间为$0.4 < z^{mathrm{ch}}_{||} < 1.0$。同时给出了不同碰撞能量与喷注分辨参数下的结果对比。将本次测量结果与基于领头阶（leading-order, LO）和次领头阶（next-to-leading-order, NLO）微扰量子色动力学（perturbative quantum chromodynamics, pQCD）计算的蒙特卡洛事件产生器（Monte Carlo event generators）的理论预言进行了对比。尽管在低带电喷注横向动量区间存在少量偏差，但整体上理论预言能够较好地描述实验数据的主要特征。本研究还完成了√s=5.02 TeV下$R=0.3$时的测量，并将该结果及其与理论预言的对比展示于本文附录中。