论文标题
$ \ sqrt {s} = $ 7 TEV的$υ$（ns）相对产生的事件活性依赖性调查
Investigation into the event-activity dependence of $Υ$(nS) relative production in proton-proton collisions at $\sqrt{s} = $ 7 TeV
论文作者
论文摘要
激发$υ$（2s）和$υ$（3s）介子与$υ$（1S）基层之间的生产横截面的比率是通过其衰减为两个muons检测到的$υ$（1S）的状态，这是事件发生的充电粒子数量的函数。数据来自$ \ sqrt {s} = $ 7 TEV的Proton-Proton碰撞，对应于4.8 fb $^{ - 1} $的集成光度，并在LHC上收集了CMS检测器。观察到这些比率降低的证据与粒子多样性的关系，在低横向动量$ p_ \ mathrm {t}^{μμ} $下更为明显。对于$υ$（ns）的介子，带有$ p_ \ mathrm {t}^{μμ} $ $ \ gt $ 7 GEV，在收集大多数数据的情况下，研究了与多样性的相关性，是基本事件横向球的函数的函数，并在$（$ @ $见（ns）方向周围的圆锥形粒子数量上研究。在类似喷气样事件中，发现该比率是独立的。还测量并发现，随着粒子多数性的函数，$ P_ \ MATHRM {T}^{μμ} $值也被测量，并且随着粒子质量的增加而变得更加陡峭。
The ratios of the production cross sections between the excited $Υ$(2S) and $Υ$(3S) mesons and the $Υ$(1S) ground state, detected via their decay into two muons, are studied as a function of the number of charged particles in the event. The data are from proton-proton collisions at $\sqrt{s} =$ 7 TeV, corresponding to an integrated luminosity of 4.8 fb$^{-1}$, collected with the CMS detector at the LHC. Evidence of a decrease in these ratios as a function of the particle multiplicity is observed, more pronounced at low transverse momentum $p_\mathrm{T}^{μμ}$. For $Υ$(nS) mesons with $p_\mathrm{T}^{μμ}$ $\gt$ 7 GeV, where most of the data were collected, the correlation with multiplicity is studied as a function of the underlying event transverse sphericity and the number of particles in a cone around the $Υ$(nS) direction. The ratios are found to be multiplicity independent for jet-like events. The mean $p_\mathrm{T}^{μμ}$ values for the $Υ$(nS) states as a function of particle multiplicity are also measured and found to grow more steeply as their mass increases.
