Hermitian flavor violation

The fundamental constraint on two Higgs doublet models comes from the requirement of sufficiently suppressing flavor-changing neutral currents. There are various standard approaches for dealing with this problem, but they all tend to share a common feature; all of the Higgs doublets couple very weakly to the first generation quarks. Here we consider a simple two Higgs doublet model which is able to have large couplings to the first generation, while also being safe from flavor constraints. We assume only that there is an SUf(3) flavor symmetry which is respected by the couplings of one of the Higgs doublets, and which is broken by Hermitian Yukawa couplings of the second doublet. As a result of the large permitted couplings to the first generation quarks, this scenario may be used to address the excess in W+dijet events recently observed by CDF at the Tevatron. Moreover, Hermitian Yukawa coupling matrices arise naturally in a broad class of solutions to the strong CP problem, providing a compelling context for the model.     

Leptonic flavor and CP violation

Recent neutrino oscillation data teach us that the neutrinos have masses and that they mix. We discuss two ways that can be used to probe other non-standard leptonic physics. We show that non-standard neutrino interaction can be probed in neutrino oscillation experiments and discuss sneutrino-antisneutrino mixing.     

Lepton flavor violation and seesaw symmetries

When the standard model is extended with right-handed neutrinos the symmetries of the resulting Lagrangian are enlarged with a new global U(1) _R Abelian factor. In the context of minimal seesaw models we analyze the implications of a slightly broken U(1) _R symmetry on charged lepton flavor violating decays. We find, depending on the R-charge assignments, models where charged lepton flavor violating rates can be within measurable ranges. In particular, we show that in the resulting models due to the structure of the light neutrino mass matrix muon flavor violating decays are entirely determined by neutrino data (up to a normalization factor) and can be sizable in a wide right-handed neutrino mass range.     

Flavor anarchy in a Randall-Sundrum model with 5D minimal flavor violation and a low Kaluza-Klein scale

A variant of a warped extra dimension model is presented. It is based on 5D minimal flavor violation, in which the only sources of flavor breaking are two 5D anarchic Yukawa matrices. These matrices also control the bulk masses, which are responsible for the resulting flavor hierarchy. The theory flows to a next to minimal flavor violation model where flavor violation is dominantly coming from the 3rd generation. Flavor violation is also suppressed by a parameter that dials the violation in the up or down sector. There is therefore a sharp limit in which there is no flavor violation in the down-type quark sector which, remarkably, is consistent with the observed flavor parameters. This is used to eliminate the current Randall-Sundrum flavor and CP problem. Our construction suggests that strong dynamic-based, flavor models may be built based on the same concepts.     

Minimal flavour violation and beyond

The presence of new sources of massive boosted particles associated with processes probing the electroweak scale is a logical possibility that forms a solid window towards physics beyond the standard model. Such objects when decaying into hadronic final states can easily blend with the cornucopia of jets interpolated from essentially massless fundamental QCD states. We review jet observables and algorithms that can contribute to the identification of highly boosted heavy jets and the possible searches that can make use of such substructure information. We also review previous studies by CDF of boosted massive jets and measurement of jet shape observables.     

Lepton and flavor violation in SUSY models

Lepton and flavor violating processes resulting from neutral scalar-lepton mixing are examined in the context of supersymmetric models. Contributions arising at the one-loop level for μ → eγ, μ → 3e, μμ ⇄ ee as well as for neutrinoless ββ-decay are found to be suppressed for a general class of supersymmetry breaking parameters.     

Neutrinoless double Beta decay and lepton flavor violation

We point out that extensions of the standard model with low scale (approximately TeV) lepton number violation (LNV) generally lead to a pattern of lepton flavor violation (LFV) experimentally distinguishable from the one implied by models with grand unified theory scale LNV. As a consequence, muon LFV processes provide a powerful diagnostic tool to determine whether or not the effective neutrino mass can be deduced from the rate of neutrinoless double beta decay. We discuss the role of mu-->egamma and mu-->e conversion in nuclei, which will be studied with high sensitivity in forthcoming experiments.     

RS-A4 relaxation of flavor and CP violation

I discuss a model based on an A₄ bulk flavor symmetry in the Randall-Sundrum (RS) setup. After discussing the setup and leading order results for the masses and mixings of quarks and leptons, I elaborate on the effect of higher order “cross-talk” corrections, their contributions to flavor violating processes and the resulting constraints on the model parameter space and the Kaluza-Klein (KK) mass scale. In addition, I present a systematic study of higher order corrections to the PMNS matrix in light of the recent measurements of θ ₁₃?>?0 by RENO and Daya Bay. Finally, I also comment on the model new physics contributions to $B_{s,d}\to\mu^{+}\mu^-$ and μ → eγ, in light of the new upper bounds recently set by the LHCb and MEG experiment.     

Supersymmetry and quenched random fields beyond the tree approximation

We show how to generalize the Parisi-Sourlas treatment of quenched random fields to include corrections to the tree approximation.     

Spontaneous parity violation and minimal Higgs models

In this paper we present a model for the spontaneous breaking of parity with two Higgs doublets and two neutral Higgs singlets which are even and odd under -parity. The condition can be satisfied without introducing bidoublets, and it is induced by the breaking of -parity through the vacuum expectation value of the odd Higgs singlet. Examples of left–right symmetric and mirror fermions models in grand unified theories are presented. PACS 12.60.Cn; 14.80.Cp; 12.10.Dm     

Spontaneous CP violation and minimal coupling to supergravity

In the framework of minimal coupling to supergravity, it is found that the assumption of spontaneous CP violation allows one to generate naturally real couplings between the high-energy and the low-energy sectors of the theory, at the grand unification scale M_x. These boundary conditions for the renormalization group equations imply sufficiently small imaginary parts of these couplings at the weak scale M_w, to ensure that the experimental bound on the electric dipole moment of the neutron is respected.     

Leptonic minimal flavour violation in warped extra dimensions

Lepton mass hierarchies and lepton flavour violation are revisited in the framework of Randall?CSundrum models. Models with Dirac-type as well as Majorana-type neutrinos are considered. The five-dimensional c-parameters are fit to the charged lepton and neutrino masses and mixings using ?? ² minimization. Leptonic flavour violation is shown to be large in these cases. Schemes of minimal flavour violation are considered for the cases of an effective LLHH operator and Dirac neutrinos and are shown to significantly reduce the limits from lepton flavour violation.     

Experimental violation of Bell's inequality beyond Tsirelson's bound

The correlations between two qubits belonging to a three-qubit system can violate the Clauser-Horne-Shimony-Holt-Bell inequality beyond Tsirelson's bound [A. Cabello, Phys. Rev. Lett. 88, 060403 (2002)]. We experimentally demonstrate such a violation by 7 standard deviations by using a three-photon polarization-entangled Greenberger-Horne-Zeilinger state produced by Type-II spontaneous parametric down-conversion. In addition, using part of our results, we obtain a violation of the Mermin inequality by 39 standard deviations.     

Charged lepton flavor violation: An experimenter’s guide

Charged lepton flavor violation (CLFV) is a clear signal of new physics; it directly addresses the physics of flavor and of generations. The search for CLFV has continued from the early 1940s, when the muon was identified as a separate particle, until today. Certainly in the LHC era the motivations for continued searches are clear and have been covered in many reviews. This review is focused on the experimental history with a view toward how these searches might progress. We examine the status of searches for charged lepton flavor violation in the muon, tau, and other channels, and then examine the prospects for new efforts over the next decade. Finally, we examine what paths might be taken after the conclusion of upcoming experiments and what facilities might be required.     

Muon anomalous magnetic moment and lepton flavor violation in MSSM

We give a thorough analysis of the correlation between the muon anomalous magnetic moment and the radiative lepton flavor violating (LFV) processes within the minimal supersymmetric standard model. We find that in the case when the slepton mass eigenstates are nearly degenerate, , coming from SUSY contributions, hardly depends on the lepton flavor mixing and, thus, there is no direct relation between and the LFV processes. On the contrary, if the first two generations' sleptons are much heavier than the third one, i.e., in the effective SUSY scenario, the two quantities are closely related. In the latter scenario, the SUSY parameter space to account for the experimental is quite different from the case of no lepton flavor mixing. Especially, the Higgsino mass parameter can be either positive or negative.Received: 10 May 2003, Revised: 27 June 2003, Published online: 29 August 2003