58,533 research outputs found
Bounds on the lightest Higgs boson mass with three and four fermion generations
We present lower bounds on the Higgs boson mass in the Standard Model with
three and four fermion generations SM(3,4), as well as upper bounds on the
lightest Higgs boson mass in the minimal supersymmetric extension of the SM
with three and four generations MSSM(3,4). Our analysis utilizes the SM(3,4)
renormalization-group-improved one-loop effective potential of the Higgs boson
to find the upper bounds on the Higgs mass in the MSSM(3,4) while the lower
bounds in the SM(3,4) are derived from considerations of vacuum stability. All
the bounds increase as the degenerate fourth generation mass increases,
providing more room in theory space that respects the increasing experimental
lower limit of the Higgs mass.Comment: 24 pages, 10 figures, Some additional discussion added. Final version
to be published in International Journal of Modern Physics
Neutrino Oscillations and Lepton Flavor Mixing
In view of the recent announcement on non-zero neutrino mass from
Super-Kamiokande experiment, it would be very timely to investigate all the
possible scenarios on masses and mixings of light neutrinos. Recently suggested
mass matrix texture for the quark CKM mixing, which can be originated from the
family permutation symmetry and its suitable breakings, is assumed for the
neutrino mass matrix and determined by the four combinations of solar,
atmospheric and LSND neutrino data and cosmological hot dark matter bound as
input constraints. The charged-lepton mass matrix is assumed to be diagonal so
that the neutrino mixing matrix can be identified directly as the lepton flavor
mixing matrix and no CP invariance violation originates from the leptonic
sector. The results favor hierarchical patterns for the neutrino masses, which
follow from the case when either solar-atmospheric data or solar-HDM
constraints are used.Comment: Latex, 9 page
Large amplitude flutter of a low aspect ratio panel at low supersonic speeds comparison of theory and experiment
Flutter boundaries, as well as flutter limit cycle amplitudes, frequencies and stresses were computed for a panel of length-width ratio 4.48 exposed to applied in-plane and transverse loads. The Mach number range was 1.1 to 1.4. The method used involved direct numerical integration of modal equations of motion derived from the nonlinear plate equations of von Karman, coupled with linearized potential flow aerodynamic theory. The flutter boundaries agreed reasonably well with experiment, except when the in-plane loading approached the buckling load. Structural damping had to be introduced, to produce frequencies comparable to the experimental values. Attempts to compute panel deflections or stress at a given point met with limited success. There is some evidence, however, that deflection and stress maxima can be estimated with somewhat greater accuracy
Multiple time scales hidden in heterogeneous dynamics of glass-forming liquids
A multi-time probing of density fluctuations is introduced to investigate
hidden time scales of heterogeneous dynamics in glass-forming liquids.
Molecular dynamics simulations for simple glass-forming liquids are performed,
and a three-time correlation function is numerically calculated for general
time intervals. It is demonstrated that the three-time correlation function is
sensitive to the heterogeneous dynamics and that it reveals couplings of
correlated motions over a wide range of time scales. Furthermore, the time
scale of the heterogeneous dynamics is determined by the
change in the second time interval in the three-time correlation function. The
present results show that the time scale of the heterogeneous dynamics
becomes larger than the -relaxation time at low
temperatures and large wavelengths. We also find a dynamical scaling relation
between the time scale and the length scale of
dynamical heterogeneity as with .Comment: 4 pages, 5 figures, to appear in Phys. Rev. E (Rapid Communications
Supersymmetric three family chiral SU(6) grand unification model from F-theory
We obtain a supersymmetric three family chiral SU(6) grand unification model
with the global family symmetry SU(3)[family] from F-theory. This model has
nice features such as all the fermion masses are reasonably generated and there
results only one pair of Higgs doublets, realizing the doublet-triplet
splitting from the family symmetry SU(3)[family]. The proton hexality is
realized toward the proton stability problem. There is a room to fit the three
gauge couplings using the F-theory flux idea and we obtain the proton lifetime
in the 10^{36-37} yr region.Comment: 5 pages, to be published in Phys. Rev.
Neutrino masses along with fermion mass hierarchy
Recently a new mechanism has been proposed to cure the problem of fermion
mass hierarchy in the Standard Model (SM) model. In this scenario, all SM
charged fermions other than top quark arise from higher dimensional operators
involving the SM Higgs field. This model also predicted some interesting
phenomenology of the Higgs boson. We generalize this model to accommodate
neutrino masses (Dirac & Majorana) and also obtain the mixing pattern in the
leptonic sector. To generate neutrino masses, we add extra three right handed
neutrinos in this model.Comment: 20 pages, the content on results and phenomenology have been
expanded, a new section on UV completion of the model has been added and also
some new references, this version has been accepted by Physical Review
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