Search results for "Fermi"
showing 10 items of 1388 documents
Systematic Study of Horizontal Gauge Theories
1995
We analyze all the possible continuous horizontal gauge groups G_H in relation with their possibility to explain m_b<<m_t. We assume that the only effective fermionic degrees of freedom correspond to the known fermions but allow the possibility of adding a right handed neutrino to each family. We assume that the Higgs fields which generate masses for these fermions, trough renormalizable Yukawa couplings, transform as an irreducible representation of SU(3)_c\otimesSU(2)_L\otimesU(1)_Y\otimesG_H. Under these assumptions we find two U(1)_H or U(1)_{H1}\otimesU(1)_{H2} models free of anomalies and able to guarantee that only the top has a renormalizable mass-generating Yukawa coupling.
Higgs decay into two photons in a warped extra dimension
2014
A detailed five-dimensional calculation of the Higgs-boson decay into two photons is performed in both the minimal and the custodially protected Randall–Sundrum (RS) model, where the Standard Model (SM) fields propagate in the bulk and the scalar sector lives on or near the IR brane. It is explicitly shown that the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_\xi $$\end{document}Rξ gauge invariance of the sum of diagrams involving bosonic fields in the SM also applies to the case of these RS scenarios. An e…
Circumstantial Evidence for Rotating Mass Matrix from Fermion Mass and Mixing Data
2002
It is shown that existing data on the mixing between up and down fermion states and on the hierarchical mass ratios between fermion generations, as far as can be so analysed at present, are all consistent with the two phenomena being both consequences of a mass matrix rotating in generation space with changing energy scale. As a result, the rotating mass matrix can be traced over some 14 orders of magnitude in energy from the mass scale of the $t$-quark at 175 GeV to below that of the atmospheric neutrino at 0.05 eV.
Updates to the Dualized Standard Model on Fermion Masses and Mixings
2003
The Dualized Standard Model has scored a number of successes in explaining the fermion mass hierarchy and mixing pattern. This note contains updates to those results including (a) an improved treatment of neutrino oscillation free from previous assumptions on neutrino masses, and hence admitting now the preferred LMA solution to solar neutrinos, (b) an understanding of the limitation of the 1-loop calculation so far performed, thus explaining the two previous discrepancies with data, and (c) an analytic derivation and confirmation of the numerical results previously obtained.
New Electroweak Formulation Fundamentally Accounting for the Effect Known as “Maximal Parity-Violation”
2006
The electroweak scheme is wholly recast, in the framework of a relativistic quantum field formalism being a covariant fermion–antifermion extension of the usual one for massive spin- $$\frac{1}{2}$$ point fermions. The new formalism is able to reread the “maximal P-violation” effect in a way restoring P and C symmetries themselves: it provides a natural “chiral field” approach, which gives evidence of the existence of a pseudoscalar (extra) charge variety anticommuting with the scalar (ordinary) one and just underlying the “maximally P-violating” phenomenology. Its zero-mass limit leads to a strict “chiral” particle theory, which remodels any massless spin- $$\frac{1}{2}$$ fermion and corre…
Study of the four-fermion final state at the Z resonance
1995
The process e+e−→, where l is a charged or a neutral lepton and f any charged fermion, is analyzed. The study uses the ALEPH data collected at LEP from 1989 to 1993 at centre-of-mass energies between 88 and 95 GeV, corresponding to almost two million hadronic Z decays and to a total integrated luminosity of 79 pb−1. For all channels, the data agree well with the standard model expectation both in shape and normalization. The indication of an excess in the\(e^ + e^ - \to \tau ^ + \tau ^ - f\bar f\) channel, reported by ALEPH in 1991, is not confirmed.
Constraining New Physics with the Fermilab Measurement ofCPViolation inB→ψKs
1999
Recently, the CDF Collaboration has reported a measurement of the CP asymmetry in the $B\ensuremath{\rightarrow}\ensuremath{\psi}{K}_{s}$ decay: ${a}_{\ensuremath{\psi}{K}_{s}}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.79}_{\ensuremath{-}0.44}^{+0.41}$. We analyze the constraints that follow from this measurement on the size and the phase of contributions from new physics to $B\ensuremath{-}\overline{B}$ mixing. Defining the relative phase between the full ${M}_{12}$ amplitude and the standard model contribution to be $2{\ensuremath{\theta}}_{d}$, we find a new bound: $\mathrm{sin}2{\ensuremath{\theta}}_{d}\ensuremath{\gtrsim}\ensuremath{-}0.6(\ensuremath{-}0.87)$ at $1\ensuremat…
Search for Diphoton Events with Large Missing Transverse Energy in6.3 fb−1ofpp¯Collisions ats=1.96 TeV
2010
We report a search for diphoton events with large missing transverse energy produced in p (p) over bar collisions at root s = 1.96 TeV. The data were collected with the D0 detector at the Fermilab ...
Search forZZandZγ*Production inpp¯Collisions ats=1.96 TeVand Limits on AnomalousZZZandZZγ*Couplings
2008
We present a study of mu mu mu mu, eeee, and mu mu ee events using 1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. Requiring t ...
In-Medium Properties of theD13(1520) Nucleon Resonance
2001
The in-medium properties of the ${\mathrm{D}}_{13}(1520)$ nucleon resonance were studied via photoproduction of ${\ensuremath{\pi}}^{0}$ mesons from nuclei (C, Ca, Nb, Pb) with the TAPS detector at the Mainz Microton accelerator. The inclusive (single and multiple pion production) data disagree with model predictions which explain the disappearance of the second resonance bump in total photoabsorption via a medium modification of the ${\mathrm{D}}_{13}\ensuremath{\rightarrow}\mathrm{N}\ensuremath{\rho}$ decay. The exclusive single ${\ensuremath{\pi}}^{0}$ production data show no broadening of the resonance structure beyond Fermi smearing. Both results together cast doubt on attempts to expl…