我们提出了新的机制,改善的卡鲁扎-克莱因(KK)质量标度的约束带电轻子味破坏的标准模型(SM)的框架内传播的一个扭曲的额外的维度,特别是在模型占中微子数据。这些机制利用了扩展的五维(5D)电弱规范对称性[SU(2)_L x SU(2)_R x U(1)_X],为了满足该框架中的电弱精确测试,该规范对称性已经被强烈地激发。在这种对称性下,轻子表示的新选择(自然地)可以允许左手(LH)带电轻子的小混合角,同时允许它们的SU(2)_L伙伴的大混合角,即,LH中微子,中微子数据被占后者的混合。因此,在这些模型中,可以避免由在轻子带电电流中观察到的大混合角引起的带电轻子味违反的增强,该混合角存在于LH带电轻子和中微子混合角相似的表示的最小选择中。这个想法也可能是有用的抑制贡献B_{d, s}混合在这个框架中,为了抑制味道违反超伴侣(而不是从KK模式)在5D“美味超对称”模型。此外,较少的最小表示可以为费米子与Z的耦合转移提供监护保护,进而进一步抑制在扭曲的额外维度场景中来自树级Z交换的带电轻子味道违反。结果表明,即使在弯曲额外维的框架下,~O(3)TeV KK质量标度的5D味参数没有任何特殊结构,也能同时与带电轻子味破坏和中微子数据相一致。
英文摘要:
We propose new mechanisms for ameliorating the constraints on the Kaluza-Klein (KK) mass scale from charged lepton flavor violation in the framework of the Standard Model (SM) fields propagating in a warped extra dimension, especially in models accounting for neutrino data. These mechanisms utilize the extended five-dimensional (5D) electroweak gauge symmetry [SU(2)_L x SU(2)_R x U(1)_X] which is already strongly motivated in order to satisfy electroweak precision tests in this framework. New choices of representations for leptons under this symmetry (naturally) can allow small mixing angles for left-handed (LH) charged leptons and simultaneously large mixing angles for their SU(2)_L partners, i.e., the LH neutrinos, with the neutrino data being accounted for by the latter mixings. Enhancement of charged lepton flavor violation by the large mixing angle observed in leptonic charged currents, which is present for the minimal choice of representations where the LH charged lepton and neutrino mixing angles are similar, can thus be avoided in these models. This idea might also be useful for suppressing the contributions to B_{d, s} mixing in this framework and in order to suppress flavor violation from superpartners (instead of from KK modes) in 5D "flavorful supersymmetry" models. Additionally, the less minimal representations can provide custodial protection for shifts in couplings of fermions to Z and, in turn, further suppress charged lepton flavor-violation from tree-level Z exchange in the warped extra-dimensional scenario. As a result, ~O(3) TeV KK mass scale can be simultaneously consistent with charged lepton flavor violation and neutrino data, even without any particular structure in the 5D flavor parameters in the framework of a warped extra dimension.
Flavorful Lepton-Number-Violating SMEFT: Loop Mixing, $0νββ$ and Rare Meson Decays
Institute of Particle and Nuclear Physics (IPNP), Faculty of Mathematics and Physics, Charles University in Prague(布拉格查理大学数学物理学院粒子与核物理研究所);Institute of Physics, Silesian University in Opava(奥帕瓦西里西亚大学物理研究所);Instituto de Física Corpuscular (IFIC), Universitat de València–CSIC(巴伦西亚大学-西班牙国家科学研究委员会粒子物理研究所);Department of Physics, University of California, Berkeley(加州大学伯克利分校物理学系)
$B$ -物理数据和味对称性表明,细夸克的质量可以低至${\cal{O}}(\mbox{TeV})$,主要衰变为第三代夸克,并突出了来自单个产生的$pp \to b μμ$签名和来自对产生的$pp \to b b μμ$。放弃味道对称性可以允许反转的夸克等级,并导致由第二代耦合引起的相当大的$pp \to j μμ$和$jj μμ$截面。末态也可能出现轻子而不是μ子,包括轻子味破坏(LFV)。相应的耦合也可以通过精确研究$B \to (X_s, K^*,ϕ) ee $分布和在$B$ -衰变中的LFV搜索来探测。我们证明了LHC在单个轻夸克产生中的灵敏度,并外推到高光度的HL-LHC。要探索相空间的大部分,需要一台强子对撞机,而这台对撞机是大型强子对撞机无法企及的,它具有$b$识别能力。
Institute for Nuclear Theory, University of Washington(华盛顿大学核理论研究所);Northwestern University(西北大学);KEK Theory Center, IPNS, KEK(高能加速器研究机构理论中心);Theoretical Division, Los Alamos National Laboratory(洛斯阿拉莫斯国家实验室理论部)
Flavour violating charged lepton decays in Little Randall-Sundrum Model
与Randall-Sundrum(RS)模型相比,Little Randall-Sundrum(Little RS)模型从风味可观测量接收显著更强的约束。本文分析了小RS中的电弱扇区对带电轻子变味衰变的影响。我们比较了该模型的预测与$μ\rightarrow e e e $,$τ\rightarrow e e e $,$τ\rightarrow μμμ$,$τ\rightarrow μe e $,$τ\rightarrow e μμ$,$μ\rightarrow e γ$和$μTi \rightarrow e Ti $的味道违反分支比的当前限制。我们还证明了主导约束来自于$μTi \rightarrow e Ti$过程,它强烈地限制了KK-1规范玻色子质量($M_{KK}$)为$\gtrsim 30.7 TeV $。然后,我们推导并表明,广义的电弱规范部门,包括膜局部动力学项(BLKT)放松这一约束$\gtrsim 12 TeV$。走向的结论,我们评论的可能性,即大味违反电流可以减轻放松的假设,关于不自然的薄和刚性的UV膜,并讨论抑制这些电流的脂肪波动膜的存在的可能性。