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arXiv 1902.09290nucl-exhep-ex
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$\sqrt{s}$ = 7 TeV pp碰撞中(反)氘核产生的多重数关系

Multiplicity dependence of (anti-)deuteron production in pp collisions at $\sqrt{s}$ = 7 TeV

ALICE Collaboration

摘要:

在这封信中,在$\sqrt{s} = 7$ TeV的pp碰撞中的氘核和反氘核的产生作为在中快度的带电粒子多重数密度的函数与ALICE探测器在LHC进行了研究。产额在中快度测量在五个多重性类和作为一个函数的氘核横向动量($p_{\rm{T}}$)。测量的强子合并模型的背景下进行了讨论。聚结参数$B_{2}$,从测量的(反)氘核和初级(反)质子的光谱中提取,表现出没有显着的$p_{\rm{T}}$依赖于$p_{\rm{T}} < 3$ GeV/ $c$,在一个简单的聚结图片的预期。在固定的横向动量每核子,$B_{2}$参数被发现从低多重pp Pb-Pb碰撞平稳下降,在定性协议与更详细的合并模型。测得的平均横向动量的(反)氘核在PP是不复制的冲击波模型计算,同时描述π介子,K介子和质子谱,在中央铅铅碰撞。之间的比率$p_{\rm{T}}$ -积分产率的氘核质子,d/p,被发现增加与带电粒子的多重性,观察到在非弹性PP碰撞在不同的质量中心的能量。的d/p比报告在很宽的范围内,从最低到最高的多重性值测量PP碰撞在LHC。

英文摘要:

In this letter, the production of deuterons and anti-deuterons in pp collisions at $\sqrt{s} = 7$ TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum ($p_{\rm{T}}$). The measurements are discussed in the context of hadron-coalescence models. The coalescence parameter $B_{2}$, extracted from the measured spectra of (anti-)deuterons and primary (anti-)protons, exhibits no significant $p_{\rm{T}}$-dependence for $p_{\rm{T}} < 3$ GeV/$c$, in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the $B_{2}$ parameter is found to decrease smoothly from low multiplicity pp Pb-Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb-Pb collisions. The ratio between the $p_{\rm{T}}$-integrated yield of deuterons to protons, d/p, is found to increase with the charged-particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC.

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