论文标题
探测混合参数$ | v_ {τn} |^2 $ for重中微子
Probe the Mixing Parameter $|V_{τN}|^2$ for Heavy Neutrinos
论文作者
论文摘要
由于难以检测最终状态taus，因此与其他混合参数相比，在当前实验中，对重中微子$ n $的混合参数$ | v_ {τn} |^2 $没有很好地研究。在本文中，我们专注于一个具有挑战性的场景，其中$ n $仅与tau风味的主动中微子混合在一起，即$ | v_ {τn} |^2 \ neq 0 $和$ | v_ {e n} |^2 = | v_v_ {μn} |^2 = 0 $。我们在$ | v_ {τn} |^2 $上得出当前约束，从稀有$ z $ -Boson衰减和electroweak Precision Data（EWPD）中得出了当前的约束。为了预测未来的限制，我们还通过Majoraana重型中微子在未来的Proton-Proton Colliders中调查了信号$ p p \ toτ^{\ pm}τ^{\ pm} j j $。为了抑制背景，两种taus都必须衰变成钝器，从而导致最终状态包含两个相同的标志muons，至少两个喷气机和中度缺失的能量。信号和相关背景过程在HL-LHC和SPPC/FCC-HH上模拟，质量中心能量为14 TEV和100 TEV。进行基于机器学习的预选和多元分析以减少背景。根据$ | v_ {τn} |^2 $的限制，根据稀有$ z $ -Boson decay和eWPD的测量值显示了重型中微子质量的限制，并在HL-LHC和SPPC/SPPC/FCC-HH上进行搜索，并具有3和20 ab $^$^$^{-1} $的集成发光性。
Because of the difficulty in detecting final state taus, the mixing parameter $|V_{τN}|^2$ for heavy neutrino $N$ is not well studied at current experiments, compared with other mixing parameters $|V_{e N}|^2$ and $|V_{μN}|^2$. In this paper, we focus on a challenging scenario where $N$ mixes with active neutrino of tau flavour only, i.e. $ |V_{τN}|^2 \neq 0 $ and $|V_{e N}|^2 = |V_{μN}|^2 = 0$. We derive current constraints on $|V_{τN}|^2$ from the rare $Z$-boson decay and electroweak precision data (EWPD). To forecast the future limits, we also investigate the signal $p p \to τ^{\pm} τ^{\pm} j j $ via a Majorana heavy neutrino at future proton-proton colliders. To suppress the background, both taus are required to decay leptonically into muons, leading to the final state containing two same sign muons, at least two jets plus moderate missing energy. The signal and relevant background processes are simulated at the HL-LHC and SppC/FCC-hh with center-of-mass energy of 14 TeV and 100 TeV. The preselection and multivariate analyses based on machine-learning are performed to reduce background. Limits on $|V_{τN}|^2$ are shown for heavy neutrino mass in the range 10-1000 GeV based on measurements from the rare $Z$-boson decay and EWPD, and searches at the HL-LHC and SppC/FCC-hh with integrated luminosities of 3 and 20 ab$^{-1}$.
