Search results for "Universality"
showing 10 items of 107 documents
Study of the D0 → K− μ+ νμ Dynamics and Test of Lepton Flavor Universality with D0→K−l+νl Decays
2020
Lepton Universality Tests with Kaons
2007
Precision data on Kl3 and Kl2 decay rates and form factors allow us to perform significant tests of lepton universality and to constrain the strength of non-standard interactions. The present status of these tests and new physics searches are discussed, as obtained by combining all the available results of the various kaon physics experiments.
Searching for new physics in bottomonium decays
2005
Heavy quarkonium decays can be used to search for New Physics beyond the Standard Model. In particular, a light Higgs boson could induce a slight (but observable) lepton universality breaking in Upsilon decays. In fact, current experimental data from CLEO presented in this Conference seem to point out to this direction within experimental accuracy. Moreover, LEP constraints on a light Higgs mass can be evaded by different models (like MSSM with a CPV Higgs sector) as shown in this Conference. We also consider spectroscopic consequences stemming from a possible mixing between Higgs and bottomonium states leading to discrepancies with the SM expectations (e.g. hyperfine splittings).
Search for heavy neutrinos in \(\pi ^{ + } \to \mu ^{ + }\nu \) decay and status of lepton universality test in the PIENU experiment
2019
International audience; In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays \(\pi ^{ + } \to \mu ^{ + }\nu \). No evidence for extra peak was found in the muon kinetic energy spectrum and 90% confidence level upper limits were set on the neutrino mixing matrix \(|U_{\mu i}|^{2}\) in the mass range of 15.7 to 33.8 MeV/c^2, improving an order of magnitude over previous experiments. Current status of lepton universality test is also reported.
Universality of lepton interactions
2005
Flavor Physics in SUSY Grand Unified Theories
2007
Within Supersymmetric Grand Unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link Flavor Changing Neutral Current (FCNC) and CP violating processes occurring in the leptonic and hadronic sectors. So, a correlated analysis of low-energy observables in the leptonic and hadronic sectors, can provide indications of the existence of a Grand Unified theory at high energies. We show how bounds on leptonic FCNC involving the third generation translate into constraints on FCNC B decays. Moreover, we show that, besides FCNC transitions, also lepton-flavor (LF) universality tests in M l 2 decays (with M = π , K , B ), offer a unique opportunity to stud…
Lepton flavor violation in a Z′ model for the b→s anomalies
2019
In recent years, several observables associated to semileptonic $b \to s$ processes have been found to depart from their predicted values in the Standard Model, including a few tantalizing hints of lepton flavor universality violation. In this work we consider an existing model with a massive $Z^\prime$ boson that addresses the anomalies in $b \to s$ transitions and extend it with a non-trivial embedding of neutrino masses. We analyze lepton flavor violating effects, induced by the non-universal interaction associated to the $b \to s$ anomalies and by the new physics associated to the neutrino mass generation, and determine the expected ranges for the most relevant observables.
Finite-size scaling for a first-order transition where a continuous symmetry is broken: The spin-flop transition in the three-dimensional XXZ Heisenb…
2019
Finite-size scaling for a first-order phase transition where a continuous symmetry is broken is developed using an approximation of Gaussian probability distributions with a phenomenological ``degeneracy'' factor included. Predictions are compared with data from Monte Carlo simulations of the three-dimensional, $XXZ$ Heisenberg antiferromagnet in a field in order to study the finite-size behavior on a $L\ifmmode\times\else\texttimes\fi{}L\ifmmode\times\else\texttimes\fi{}L$ simple cubic lattice for the first-order ``spin-flop'' transition between the Ising-like antiferromagnetic state and the canted, $XY$-like state. Our theory predicts that for large linear dimension $L$ the field dependen…
Inversion symmetric vs. asymmetric excitations and the low-temperature universal properties of Ar:N 2 and Ar:N 2 :CO glasses
2015
The bias energies of various two-level systems (TLSs) and their strengths of interactions with the strain are calculated for Ar:N2 glass. Unlike the case in KBr:CN, a distinct class of TLSs having weak interaction with the strain and untypically small bias energies is not found. The addition of CO molecules introduces CO flips which form such a class of weakly interacting TLSs, albeit at much lower coupling than that at which they are typically observed in solids. We conclude that because of the absence of a distinct class of weakly interacting TLSs, Ar:N2 is a non-universal glass, the first such system in three dimensions and in ambient pressure. Our results further suggest that Ar:N2:CO m…
Reply to "Comment on 'Systematics of radial and angular-momentum Regge trajectories of light non-strange qqbar-states' "
2013
In his Comment, D. Bugg argues against our usage of the PDG collection of light non-strange states together with the half-width rule to analyze the linearity of radial and angular-moment Regge trajectories in the large-N_c limit. After taking into account his observations on our choice of data, the radial Regge trajectories are again analyzed. We still find that our conclusion on the lack of universality between radial- and angular-momentum Regge trajectories is valid.