The first measurements of dielectron production at midrapidity $(\left|{\eta }_{\mathrm{e}}\right|<0.8)$ in proton–proton and proton–lead collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass $m_{\mathrm{ee}}$ and the pair transverse momentum $p_{\mathrm{T},\mathrm{ee}}$ in the ranges $m_{\mathrm{ee}}<3.5$ $\mathrm{GeV}/c^2$ and $p_{\mathrm{T},\mathrm{ee}}<8$ $\mathrm{GeV}/c$, in both collision systems. In proton–proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at $\sqrt{s}=7$ and 13 TeV. The slope of the $\sqrt{s}$ dependence of the three measurements is described by FONLL calculations. The dielectron cross section measured in proton–lead collisions is in agreement, within the current precision, with the expected dielectron production without any nuclear matter effects for ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ pairs from open heavy-flavor hadron decays. For the first time at LHC energies, the dielectron production in proton–lead and proton–proton collisions are directly compared at the same $\sqrt{s_{\mathrm{NN}}}$ via the dielectron nuclear modification factor $R_{\mathrm{pPb}}$. The measurements are compared to model calculations including cold nuclear matter effects, or additional sources of dielectrons from thermal radiation.

中文翻译：

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质子-质子和质子-铅碰撞中atsNN = 5.02TeV的双电子产生

中速产生双电子的首次测量 $（\left|{\eta }_{\mathrm{Ë}}\right|<0.8）$ 在质子-质子和质子-铅碰撞中 $\sqrt{s_{\mathrm{神经网络}}}=5.02\mathrm{电视}$在大型强子对撞机进行了介绍。用ALICE检测器测量双电子截面与不变质量的关系${米}_{\mathrm{ee}}$ 和一对横向动量 $p_{\mathrm{Ť}，\mathrm{ee}}$ 在范围内 ${米}_{\mathrm{ee}}<3.5$ $\mathrm{GeV}/C^2$ 和 $p_{\mathrm{Ť}，\mathrm{ee}}<8$ $\mathrm{GeV}/C$在两个碰撞系统中。在质子-质子碰撞中，通过两个不同的事件生成器对数据的拟合，在中间快速确定魅力和美丽的横截面。这补充了在$\sqrt{s}=7$和13 TeV。的斜率$\sqrt{s}$三种测量的依赖性通过FONLL计算来描述。在当前的精度范围内，质子-铅碰撞中测得的双电子截面与预期的双电子产量一致，且对${\mathrm{Ë}}^{+}{\mathrm{Ë}}^{-}$对从开放的重味强子衰变。首次在大型强子对撞机能量下，在同一时间直接比较了质子-铅碰撞和质子-质子碰撞中的电子产生$\sqrt{s_{\mathrm{神经网络}}}$ 通过双电子核修饰因子 ${\mathrm{[R}}_{铅}$。将测量结果与模型计算进行比较，包括冷核物质效应或热辐射产生的其他双电子源。