Related papers: Fourth Generation Leptons and Muon $g-2$
CMS has reported indications (2.4\sigma) of the decay of the Higgs boson into \mu\tau. The simplest explanation for such a decay would be a general Two Higgs Doublet Model (2HDM). In this case, one would expect the heavy neutral Higgs…
This study investigates the influence of the fourth generation quarks on the total branching ratio and the single lepton polarizations in \Lambda_b --> \Lambda \ell^+ \ell^- decay. Taking $|V_{t's}V_{t'b}| {0.01-0.03} with phase just below…
We study $\mu - e$ conversion with sequential four generations. A large mass for the fourth generation neutrino can enhance the conversion rate by orders of magnitude. We compare constraints obtained from $\mu - e$ conversion using…
An approximate Z_3 family symmetry is proposed for leptons which results in a neutrino mass matrix with sin^2 2 theta_atm = 1 and tan^2 theta_sol = 0.5, but the latter value could easily be smaller. A generic requirement of this approach is…
We revisit the muon magnetic moment (g-2) in the context of Composite Higgs models and Technicolor, and provide general analytical expressions for computing the muon magnetic moment stemming from new fields such as, neutral gauge bosons,…
We study the four-body heavy baryon decay, including two leptons in the final state, of the form $B_A \to B_B P \ell_\alpha \ell_\beta$, which can be either a lepton number conserving (LNC) or a lepton number violating (LNV) process (where…
One of the key assumptions of the Standard Model of fundamental particles is that the interactions of the charged leptons, namely electrons, muons, and taus, differ only because of their different masses. While precision tests have not…
We study previously unconsidered 3-3-1 models which are characterized by each lepton generation having a different representation under the gauge group. Flavor-changing neutral currents in the lepton sector occur in these models. To satisfy…
A non-universal anomaly free $U(1)_{X}$ extension to the Minimal Supersymmetric Standard Model, consisting of four scalar doublets, four scalar singlets and additional quark and lepton singlets including right-handed and Majorana neutrinos,…
We study the response of the electron mass to an externally applied electrical field. As a consequence of nonlinear electromagnetic (EM) effective action, the mass of a particle diminishes in the presence of an externally applied electric…
We present a comprehensive analysis of neutrino mass and lepton mixing in theories with $A_4$ modular symmetry, where the only flavon field is the single modulus field $\tau$, and all masses and Yukawa couplings are modular forms. Similar…
Assuming the existence of a gauge boson $X$ which couples to $B - 3 L_\tau$, we discuss the present experimental constraints on $g_X$ and $m_X$ from $Z \to l^+ l^-$ and $Z \to \bar f f X~(f = q, \nu_\tau, \tau)$. We also discuss the…
This paper addresses the role of Large Extra Dimensions in some flavor changing neutral current (FCNC) driven processes. In particular we have investigated radiative decays of charged leptons within models with only one universal extra…
In a previous work \cite{Buttazzo:2020ibd}, it has been pointed out that heavy new physics (NP) contributions to lepton dipole moments and high-energy cross-sections of lepton pairs into Higgs and $\gamma/Z$ bosons are connected, if the…
We propose a model realizes that a semi-visible dark photon which can contribute to the anomalous magnetic moment ($g-2$) of both electron and muon. In this model, the electron $g-2$ is deviated from the Standard Model (SM) prediction by…
A mechanism has been suggested recently to generate the neutrino mass out of a dimension-seven operator. This is expected to relieve the tension between the occurrence of a tiny neutrino mass and the observability of other physics effects…
We study the implications of the experimental results on the \mu -> e\gamma decay rate and the muon anomalous magnetic moment, on muonic lepton flavor violating processes, such as \mu -> 3 e and \mu N -> e N. We use a model independent…
Decays of B mesons into final states containing a tau lepton are sensitive to new charged-current interactions that break lepton-flavor universality. These decays have been studied only at e+e- colliders, where the low-background…
In neutrino physics, a class of models with local or global family symmetries may be invoked, and then a flavon field is needed to realize the full neutrino mixing. This flavon may shed light on the long-standing muon $g-2$ puzzle. In this…
We present a new and novel synthesis of all existing neutrino data regarding the disappearance and appearance of $\nu_e$ and $\nu_\mu$. We assume four neutrinos: $\nu_e, \nu_\mu, \nu_\tau$, as well as a heavier singlet neutrino $\nu_s$ of a…