论文标题
proton-proton碰撞中的软丝果过剩，$ \ sqrt {s} $ = 13 tev
Soft-dielectron excess in proton-proton collisions at $\sqrt{s}$ = 13 TeV
论文作者
论文摘要
在本信中介绍了在$ \ sqrt {s} = 13 $ tev中对质子 - 普罗顿（PP）碰撞碰撞的测量结果，该信在Cern LHC的Alice检测器中记录。用减少的磁电磁阀场记录了数据集。这使得在低二元型质量$ m _ {\ rm ee} $上对运动域的调查和横向动量$ p _ {\ rm t，ee} $以前在LHC上是无法访问的。研究了Dielectron生产的横截面作为$ M _ {\ rm EE} $，$ p _ {\ rm t，ee} $的函数和事件乘数$ {\ rm d} n _ {\ rm d}假设PP和Proton-Nucleus（P-A）碰撞的测得的$η/π^0 $比的参数化，从强子衰变（称为HADRONE鸡尾酒）中的预期二元发射速率，假设该比率没有强大的依赖对低横向动量的碰撞。比较测得的二元发元的鸡尾酒的比较$ 0.15 <m _ {\ rm ee} <0.6 $ gev/$ c^2 $，对于$ p _ {\ rm t，ee} <0.4 $ gev/$ c $在不同的实验条件下，几个实验报告了强子 - 戴隆碰撞。对HADRONIC鸡尾酒的增强因子为$ 1.61 \ pm 0.13 \，（\ rm {stat。}）\ pm 0.17 \，（\ rm {syst。，data}，data}）\ pm 0.34 \，（\ rm {syst。，cocktail}）$ in Alice cackence cartessance。提取了$ m _ {\ rm ee} $和$ p _ {\ rm t，ee} $中的接受性校正的多余光谱，并将其与Hadronic Bremsstrahlung和Hadronic多体型方法中的Hadronic Bremsstrahlung和Thermal辐射进行了比较。
A measurement of dielectron production in proton-proton (pp) collisions at $\sqrt{s} = 13$ TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron invariant mass $m_{\rm ee}$ and pair transverse momentum $p_{\rm T,ee}$ that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of $m_{\rm ee}$, $p_{\rm T,ee}$, and event multiplicity ${\rm d} N_{\rm ch}/{\rm d} η$. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured $η/π^0$ ratio in pp and proton-nucleus (p-A) collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at $0.15<m_{\rm ee}<0.6$ GeV/$c^2$ and for $p_{\rm T,ee} < 0.4$ GeV/$c$ indicates an enhancement of soft dielectrons, reminiscent of the 'anomalous' soft-photon and -dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to $1.61\pm 0.13\,(\rm{stat.})\pm 0.17\,(\rm{syst., data}) \pm 0.34\,(\rm{syst., cocktail})$ in the ALICE acceptance. Acceptance-corrected excess spectra in $m_{\rm ee}$ and $p_{\rm T,ee}$ are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.
