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arXiv 2011.03686hep-ph
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LHC上稀有轻子数违反$W$衰变的CP破坏

CP Violation in Rare Lepton-Number-Violating $W$ Decays at the LHC

Fatemeh Najafi, Jacky Kumar, David London

备注：
19 pages, 2 figures, (i) we have made the motivation more generic, so that it refers to any leptogenesis model that contains a quasi-Dirac pair of almost-degenerate neutrinos, not just the nuMSM,(ii) we focus only on the l^- l^- (q' qbar)^+ final state, since it is purely LNV (the trilepton final state has both LNV and LNC contributions). We have also added references and corrected typos."
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摘要：

一些稀薄成因的模型涉及一对准简并的重中微子$N_{1,2}$，它的质量可以很小，$O({\rm GeV})$。这样的中微子可以促成罕见的轻子数破坏（LNV）衰变$W^\pm \to \ell_1^\pm \ell_2^\pm (q'{\bar q})^\mp$。如果$N_1$和$N_2$都有贡献，则在$W^-$的LNV衰变和其CP共轭衰变之间可能存在CP破坏速率差。在本文中，我们研究了在LHC测量这种CP不对称性$A_{\rm CP}$的前景。我们假设一个值的重轻中微子混合参数$|B_{\ell N}|^2 = 10^{-5}$，这是允许由目前的实验约束，并考虑$5~{\rm GeV} \le M_N \le 80~{\rm GeV}$。我们考虑三个版本的大型强子对撞机- HL-LHC，HE-LHC，FCC-hh -和显示，CP不对称的小值可以测量在$3σ$，在范围$1\% \lesssim A_{\rm CP} \lesssim 15\%$。

英文摘要：

Some models of leptogenesis involve a quasi-degenerate pair of heavy neutrinos $N_{1,2}$ whose masses can be small, $O({\rm GeV})$. Such neutrinos can contribute to the rare lepton-number-violating (LNV) decay $W^\pm \to \ell_1^\pm \ell_2^\pm (q'{\bar q})^\mp$. If both $N_1$ and $N_2$ contribute, there can be a CP-violating rate difference between the LNV decay of a $W^-$ and its CP-conjugate decay. In this paper, we examine the prospects for measuring such a CP asymmetry $A_{\rm CP}$ at the LHC. We assume a value for the heavy-light neutrino mixing parameter $|B_{\ell N}|^2 = 10^{-5}$, which is allowed by the present experimental constraints, and consider $5~{\rm GeV} \le M_N \le 80~{\rm GeV}$. We consider three versions of the LHC -- HL-LHC, HE-LHC, FCC-hh -- and show that small values of the CP asymmetry can be measured at $3σ$, in the range $1\% \lesssim A_{\rm CP} \lesssim 15\%$.

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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