ALICE中的粒子识别：贝叶斯方法
Particle identification in ALICE: a Bayesian approach
摘要：
我们提出了一种贝叶斯方法的粒子识别（PID）在ALICE实验。其目的是更有效地结合各种探测器的粒子识别能力。在简要解释了所采用的方法和形式主义，贝叶斯PID方法的性能进行了研究的中心桶的ALICE的带电π介子，K介子和质子。PID通过测量比能量损失（$\mathrm{d}E/\mathrm{d}x$）和飞行时间来执行。提取PID效率和错误识别概率，并与Monte Carlo模拟使用高纯度样品的衰变通道${\rm K}^0_S \rightarrow π^-π^+$，$ϕ\rightarrow {\rm K}^-{\rm K}^+$，和$Λ\rightarrow {\rm p}π^-$在p-Pb碰撞在$\sqrt{s_{\rm NN}}=5.02$ TeV的识别粒子进行比较。为了彻底评估贝叶斯方法的有效性，这种方法被用来获得修正的$p_{\rm T}$谱的π介子，K介子，质子，和D $^0$介子在pp碰撞在$\sqrt{s}=7$ TeV。在所有情况下，发现使用贝叶斯PID的结果与ALICE使用标准PID方法进行的先前测量一致。对于D $^0 \rightarrow {\rm K}^-π^+$的测量，发现当与标准PID选择相比时，贝叶斯PID方法给出更高的信号背景比和相似或更大的统计显著性，尽管识别效率降低。最后，我们提出了一个探索性的研究测量$Λ_{\rm c}^{+}\rightarrow {\rm p} {\rm K}^-π^+$ PP碰撞在$\sqrt{s}=7$ TeV，使用贝叶斯方法识别其衰变产物。
英文摘要：
We present a Bayesian approach to particle identification (PID) within the ALICE experiment. The aim is to more effectively combine the particle identification capabilities of its various detectors. After a brief explanation of the adopted methodology and formalism, the performance of the Bayesian PID approach for charged pions, kaons and protons in the central barrel of ALICE is studied. PID is performed via measurements of specific energy loss ($\mathrm{d}E/\mathrm{d}x$) and time-of-flight. PID efficiencies and misidentification probabilities are extracted and compared with Monte Carlo simulations using high-purity samples of identified particles in the decay channels ${\rm K}^0_S \rightarrow π^-π^+$, $ϕ\rightarrow {\rm K}^-{\rm K}^+$, and $Λ\rightarrow {\rm p}π^-$ in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. In order to thoroughly assess the validity of the Bayesian approach, this methodology was used to obtain corrected $p_{\rm T}$ spectra of pions, kaons, protons, and D$^0$ mesons in pp collisions at $\sqrt{s}=7$ TeV. In all cases, the results using Bayesian PID were found to be consistent with previous measurements performed by ALICE using a standard PID approach. For the measurement of D$^0 \rightarrow {\rm K}^-π^+$, it was found that a Bayesian PID approach gave a higher signal-to-background ratio and a similar or larger statistical significance when compared with standard PID selections, despite a reduced identification efficiency. Finally, we present an exploratory study of the measurement of $Λ_{\rm c}^{+}\rightarrow {\rm p} {\rm K}^-π^+$ in pp collisions at $\sqrt{s}=7$ TeV, using the Bayesian approach for the identification of its decay products.
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