We compare the sensitivity of precision measurements of lepton flavour observables to the reach of the LHC in a case study of lepton-flavour violating operators of dimension six with two leptons and two quarks. For light quarks precision measurements always yield the more stringent constraints. The LHC complements precision measurements for operators with heavier quarks. Competitive limits can already be set on the cutoff scale $Λ$ > 600 - 800 GeV for operators with right-handed $τ$ leptons using the LHC run 1 data.
We explore possible signatures for charged lepton flavour violation (LFV), sparticle discovery at the LHC and dark matter (DM) searches in grand unified theories (GUTs) based on SU(5), flipped SU(5) (FSU(5)) and SU(4)$_c \times $SU(2)$_L \times $SU(2)$_R$ (4-2-2). We assume that soft supersymmetry-breaking terms preserve the group symmetry at some high input scale, and focus on the non-universal effects on different matter representations generated by gauge interactions at lower scales, as well as the charged LFV induced in Type-1 see-saw models of neutrino masses. We identify the different me…
A new process with the lepton flavor violation (LFV) is presented in the setup for LHC. The LFV is induced by the one-loop effect through Higgs bosons in the framework of the type-III two Higgs doublet model. It is demonstrated that the vast of parameter space in the Yukawa sector could be accessed by current and future LHC experiments.
The discrepancy between the measured value and the Standard Model prediction for the muon anomalous magnetic moment is one of the important issues in the particle physics. In this paper, we consider a two Higgs doublet model (2HDM) where the extra Higgs doublet couples to muon and tau in lepton flavor violating (LFV) way and the one-loop correction involving the scalars largely contributes to the muon anomalous magnetic moment. The couplings should be sizable to explain the discrepancy, so that the extra Higgs bosons would dominantly decay into $μτ$ LFV modes, which makes the model testable at…
基于真实模拟研究了大型强子对撞机(LHC)最小超对称标准模型(MSSM)中轻子味破坏(LFV)的测量。我们考虑的LFV衰变的第二个最轻的中性伴子,$\tildeχ^0_2 \to \tilde{l} l' \to l l' \tildeχ^0_1$的情况下,味混合存在于右手slepton。我们扫描的参数空间的最小超引力模型(MSUGRA)和一个更通用的模型,我们把希格斯诺质量$μ$作为一个自由参数。我们发现,如果$μ$小于MSUGRA的预测,在LHC观测到LFV的可能性更高; LHC的LFV搜索可以覆盖$μ\to e γ$衰变可以被抑制的参数范围,在这种情况下的图之间的取消。
Leptoquarks (LQ) with couplings to the third generation of Standard Model (SM) quarks have been proposed as possible explanations of the flavour anomalies indicating the violation of lepton flavour universality (LFV). The CMS collaboration has initiated an extensive search programme for these new states in the LHC run-2 data recorded at $\sqrt{s}=13$ TeV. In this article, the CMS search results in the LQ pair-production final states $τb\,τb$, $νt\,νt$, $νb\,νb$, $τt\,τt$, and $μt\,μt$, as well as in the LQ single-production final state $τ\,τb$ are discussed. No significant deviation from the S…
在这篇评论文章中,我们强调的影响模型,将味对称性带电轻子味违反(LFV)的过程。味对称性提供了一个自然的方法来解释特殊的质量等级和混合模式的标准模型费米子。新的LFV源通常存在于标准模型之外的新物理中,并且味道对称性可以对LFV观测值做出独特的预测。他们的发现可以为区分味道对称性和新的物理场景提供重要信息。由于它们的高灵敏度,我们将专注于寻找低能LFV过程,如原子核中的μ-> e γ或μ-e转换,但我们也将强调LFV过程在LHC中的潜在影响。如果新的物理学在大型强子对撞机可以达到的尺度上发生,那么它们诱导的味道算子可能会被高度详细地探测。
Starting from a general effective Lagrangian for lepton flavor violation (LFV) in quark-lepton transitions, we derive constraints on the effective coefficients from the high-mass tails of the dilepton processes $pp \to \ell_k \ell_l$ (with $k\neq l$). The current (projected) limits derived in this paper from LHC data with $36~\mathrm{fb}^{-1}$ ($3~\mathrm{ab}^{-1}$) can be applied to generic new physics scenarios, including the ones with scalar, vector and tensor effective operators. For purely left-handed operators, we explicitly compare these LHC constraints with the ones derived from flavor…
$B$-physics data and flavor symmetries suggest that leptoquarks can have masses as low as few ${\cal{O}}(\mbox{TeV})$, predominantly decay to third generation quarks, and highlight $pp \to b μμ$ signatures from single production and $pp \to b b μμ$ from pair production. Abandoning flavor symmetries could allow for inverted quark hierarchies, and cause sizable $pp \to j μμ$ and $jj μμ$ cross sections, induced by second generation couplings. Final states with leptons other than muons including lepton flavor violation (LFV) ones can also arise. The corresponding couplings can also be probed by pr…
Upcoming searches for lepton flavour change (LFV) aim to probe New Physics(NP) scales up to $ \sim 10^4$ TeV, implying that they will be sensitive to NP at lower scales that is suppressed by loops or small couplings. We suppose that the NP responsable for LFV is beyond the reach of the LHC and can be parametrised in Effective Field Theory, introduce a small power-counting parameter à la Cabibbo-Wolfenstein, and assess whether the existing dimension six operator basis and one-loop RGEs provide a good approximation for LFV. We find that mu to e flavour-changing observables can be sensitive to a …
In this work we present a model-independent search strategy at the LHC for heavy Higgs bosons decaying into a tau and a muon, $H/A \rightarrow τμ$, showing a plausible tendency to improve the sensitivity obtained by the present experimental limits. This search strategy is performed for the Higgs boson mass range 1-5 TeV and uses as the most relevant kinematical variables, in order to discriminate signal against background, the transverse momenta of the muon and the tau together with the missing transverse energy. We estimate the exclusion limits at 95% C.L. and the significances for evidence a…
Polytechnic University of the Philippines(菲律宾理工大学)
The discovery of neutrino oscillation, proving that neutrinos do have masses, reveals the misfits of particles in the current Standard Model (SM) theory. In theory, neutrinos having masses could result in lepton flavour not being a symmetry called Lepton Flavour Violation (LFV). While SM theory extensions allowed LFV processes, their branching fractions are too small, making them unobservable even with the strongest equipment up-to-date. With that, scientists in recent years have generated LFV-like processes from the combined LHCb and Monte-Carlo-Simulated data in an attempt to identify LFV us…
Right-handed neutrinos in supersymmetric models can act as the source of lepton flavor violation (LFV). We present experimental implications of lepton flavor-violating processes within a supersymmetric type-I seesaw framework in the three-extra-parameter non-universal Higgs model (NUHM3) for large (PMNS-like) and small (CKM-like) Yukawa mixing scenarios. We highlight LFV predictions for the natural (low $Δ_{\rm EW}$) portion of parameter space. Our numerical analysis includes full 2-loop renormalization group running effects for the three neutrino masses and mass matrices. We show the projecte…
Lepton-flavor violating decays of neutral Higgs to muon and tauon in supersymmetric economical 3-3-1 model
在超对称经济3 - 3 - 1(SUSYE331)模型中研究了Higgs粒子到μ子-τ子的轻子味破坏(LFV)衰变.在sleptons {mu,tau}中存在风味混合和大的v/v '值时,Br(H--> tau ^+ mu ^-)/Br(H--> tau ^+ tau ^-)的比率可以达到不可忽略的值O(10 ^{-3}),如在许多已知的SUSY模型中那样。我们预测,对于标准模型的希格斯玻色子,大型强子对撞机可能会检测到它衰变为μ子和τ子。我们还研究了左右LFV修正值之间的不对称性,证明了LFV效应主要由左FLV项控制,在小的数值极限下,左FLV项比右LFV项大O(10^3)倍。|μ_ρ|/m_SUSY。Higgs介导的影响的衰变τ-->亩的贡献进行了讨论。
We re-examine lepton flavor violation (LFV) in the Littlest Higgs model with T--parity (LHT) including the full T--odd (non-singlet) lepton and Goldstone sectors. The heavy leptons induce two independent sources of LFV associated with the couplings necessary to give masses to the T--odd mirror fermions and to their partners in right-handed $SO(5)$ multiplets, respectively. The latter, which have been neglected in the past, can be decoupled from gauge mediated processes but not from Higgs mediated ones and must therefore also be included in a general analysis of LFV in the LHT. We also further …
Axion-Like Particles (ALPs) are pseudo Nambu-Goldstone bosons associated with spontaneously broken global $U(1)$ symmetries. Such particles can have lepton-flavor-violating (LFV) couplings to the SM charged leptons. LFV ALPs provide the possibility to address some of the SM long-lasting problems. We investigate the sensitivity of a future muon collider suggested by the Muon Accelerator Program (MAP) to the production of LFV ALPs in the ALP mass range $m_a\leq1$ MeV. ALPs are assumed to be produced through the LFV decay $τ\ra\ell a$ ($\ell=e,μ$) of one of the tau leptons produced in the muon-an…
Motivated by the rencent LHC data on the lepton-flavor violating (LFV) decays $h\to \ell_1 \ell_2$ and $B_{s,d}\to \ell_1 \ell_2$, we study the Higgs-mediated flavor-changing neutral current (FCNC) interactions in the effective field theory (EFT) approach without and with the minimal flavor violation (MFV) hypothesis, and concentrate on the later. After considering the $B$ and $K$ physics data, the various LFV processes, and the LHC Higgs data, severe constraints on the Higgs FCNC couplings are derived, which are dominated by the LHC Higgs data, the $B_s - \bar B_s$ mixing, and the $μ\to e γ$ …
The heavy right-handed neutrinos in supersymmetric models can act as the source of lepton flavor violation (LFV). LFV processes like $ μ\rightarrow e γ$, $ τ\rightarrow μγ$, $ τ\rightarrow e γ$ is an effective way to explore new physics beyond the SM. Among the possible processes, $ μ$ decays have the greatest discovery potential in most of the supersymmetric models. Experimental inference of lepton flavor-violating processes within a supersymmetric type-II seesaw framework in the non-universal Higgs model (NUHM) and non-universal Scalar Mass model for Yukawa mixing scenarios in the $ S_{4} $ …