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arXiv 2412.19952hep-ex
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B$^0_\mathrm{s}$→J/$ψ\,ϕ$(1020)衰变中混合诱导CP violation首次证据的初步证据

First evidence for mixing-induced $CP$ violation in B$^0_\mathrm{s}$ $\to$ J/$ψ\,ϕ$(1020) decays in pp collisions at $\sqrt{s} = $ 13 TeV

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)(欧洲核子研究中心(CERN))

CMS Collaboration

AI总结:

利用机器学习方法对B$^0_\mathrm{s}$→J/$ψ\,ϕ$(1020)衰变进行味标记,测量B$^0_\mathrm{s}-\overline{\mathrm{B}}^grow_\mathrm{s}$系统弱相位,发现混合诱导CP violation的首个证据。

摘要:

一种结合同侧和反侧标记的机器学习风味标记算法被用于从13 TeV质子-质子碰撞中获得相当于27000个标记的B$^0_\mathrm{s}$→J/$ψ\,ϕ$(1020)衰变,由CMS实验收集,对应于96.5 fb$^{-1}$的积分亮度。对μ+μ-K+K-最终态的时间和味依赖角分析,一致于ϕ(1020)→K+K-衰变,用于测量B$^0_\mathrm{s}-\overline{\mathrm{B}}^0_\mathrm{s}$系统的参数。弱相位测量为ϕ_s = -73±22(stat)±10(syst)毫辐射,结合8 TeV CMS结果得到ϕ_s = -75±23毫辐射,与零值相差3.2个标准差,为B$^0_\mathrm{s}$→J/$ψ\,ϕ$(1020)衰变中混合诱导CP violation提供首次证据。所有测量的物理参数均与标准模型预测一致。

英文摘要:

A novel machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27$\,$000 tagged B$^0_\mathrm{s}$ $\to$ J/$ψ\, ϕ$(1020) decays from pp collisions at $\sqrt{s}$ $=$ 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 96.5 fb$^{-1}$. A time- and flavor-dependent angular analysis of the $μ^+μ^-$K$^+$K$^-$ final state, consistent with a $ϕ$(1020) $\to$ K$^+$K$^-$ decay, is used to measure parameters of the $\mathrm{B}^0_\mathrm{s}-\overline{\mathrm{B}}^0_\mathrm{s}$ system. The weak phase is measured to be $ϕ_\mathrm{s}$ = $-$73 $\pm$ 22 (stat) $\pm$ 10 (syst) mrad, which, combined with the $\sqrt{s}$ $=$ 8 TeV CMS result, gives $ϕ_\mathrm{s}$ = $-$75 $\pm$ 23 mrad. This value differs from zero by 3.2 standard deviations, providing the first evidence for mixing-induced $CP$ violation in B$^0_\mathrm{s}$ $\to$ J/$ψ\,ϕ$(1020) decays. All measured physics parameters are found to agree with standard model predictions where available.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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