用CERES进行双轻子测量
Dilepton measurements with CERES
摘要：
本文报道了在CERN SPS最高能量下，利用升级的CERES实验对中心铅-金碰撞进行的双轻子测量。改进质量分辨率的2000年数据的双轻子质谱显示出比强子衰变的预期更高的增强，这可以通过包括$ρ$谱函数的强加宽的模型来很好地描述。测量的超额产量不包括质量下降的情况。我们还报道了在高能重离子碰撞中首次同时在$K^+K^-$和双轻子衰变通道中测量到的$ϕ$介子。一个很好的协议之间的快度密度和测量的横动量谱的形状。这些数据排除了在95%CL时轻子通道中的$ϕ$产额比强子通道中的大1.6倍的可能增强。CERES结果与NA 49结果一致。
英文摘要：
We report on dilepton measurements for central Pb on Au collisions at the top CERN SPS energy with the upgraded CERES experiment. The dilepton mass spectrum of 2000 data with improved mass resolution shows an enhancement over the expectation from hadron decays that is well described by a model including a strong broadening of the $ρ$ spectral function. The measured excess yield excludes the dropping mass scenario. We also report on the $ϕ$ meson measured simultaneously both in the $K^+K^-$ and in the dilepton decay channel for the first time in high energy heavy-ion collisions. An excellent agreement is found between the rapidity densities and the shape of the measured tranverse momentum spectrum. The data rule out a possible enhancement of the $ϕ$ yield in the leptonic over hadronic channel by a factor larger than 1.6 at 95% CL. CERES results are in agreement with NA49 results.
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