Neutrino Masses, Lepton Flavor Violations, and Flavor Changing Neutral Currents in the Composite Little Higgs Model

title: Neutrinos in the Simplest Little Higgs Model
abstract: The simplest little Higgs model based on a SU(3) global symmetry contains a $SU(3)_{weak}$ triplet and a singlet per a generation in the lepton sector. A neutral component of the triplet and the singlet turn into a neutral vector-like $SU(2)_L$ singlet after electroweak symmetry breaking while the other neutral component of the triplet is the SM neutrino. At tree level, Yukawa couplings of the lepton sector not only allow the neutral vector-like lepton to couple to the SM neutrino, but also give them a Dirac mass. Majorana mass terms for the SM neutrinos and their partners arise at one loops, leading to neutrino flavor mixing in addition to neutrino-heavy neutral lepton mixing.

title: A vector-like heavy quark in the littlest Higgs model
abstract: The littlest Higgs model contains a new vector-like heavy quark in the up sector. There are two interesting features of its existence. One is that it extends the 3 × 3 CKM matrix in the standard model to a 4 × 3 matrix and the other is that it allows Z-mediated flavor changing neutral currents at tree level in the up sector but not in the down sector. We examine a few of possible windows in which the Z-mediated flavor changing neutral currents in the littlest Higgs model can be tested.

title: Expression of Interest for the Study of Nucleon Decay and Neutrino Physics Using a Large Underground Water Cherenkov Detector

title: Lepton flavor violation as a probe of quark-lepton unification
abstract: The recent measurements of the solar neutrino mixing angle {theta}{sub sol} and the Cabibbo mixing angle {theta}{sub C} reveal a surprising relation, , which has been interpreted as an evidence for quark-lepton unification. We show in realizations of quark-lepton unification that the PMNS mixing matrix can be decomposed into a CKM-like matrix and maximal mixing matrices. We explore a possibility to probe such implications by considering the relative sizes of branching ratios for the lepton flavor violating radiative decay processes, l{sub i}{yields}l{sub j}{gamma}, in the context of the supersymmetric standard model with heavy right-handed Majorana neutrinos.

title: Constraints on the R-parity and lepton flavor violating couplings from B0 decays to two charged leptons
abstract: We derive the upper bounds on certain products of R-parity- and lepton-flavor-violating couplings from the decays of the neutral $B$ meson into two charged leptons. These modes of $B^0$ decays can constrain the product combinations of the couplings with one or more heavy generation indices. We find that most of these bounds are stronger than the previous ones.

title: Dark energy from vacuum entanglement
abstract: We suggest that vacuum entanglement energy associated with the entanglement entropy of the universe is the origin of dark energy. The observed properties of dark energy can be explained by using the nature of entanglement energy without modification of gravity or exotic matter. From the number of degrees of freedom in the standard model, we obtain the equation of state parameter and for the holographic dark energy, which are consistent with current observational data at the 95% confidence level.

title: Order-αs corrections to the quarkonium electromagnetic current at all orders in the heavy-quark velocity
abstract: We compute in order {alpha}{sub s} the nonrelativistic QCD (NRQCD) short-distance coefficients that match quark-antiquark operators of all orders in the heavy-quark velocity v to the electromagnetic current. We employ a new method to compute the one-loop NRQCD contribution to the matching condition. The new method uses full-QCD expressions as a starting point to obtain the NRQCD contribution, thus greatly streamlining the calculation. Our results show that, under a mild constraint on the NRQCD operator matrix elements, the NRQCD velocity expansion for the quark-antiquark-operator contributions to the electromagnetic current converges. The velocity expansion converges rapidly for approximate J/{psi} operator matrix elements.