579 research outputs found
Phase Diagram of Gross-Neveu Model at Finite Temperature, Density and Constant Curvature
We discuss a phase structure of chiral symmetry breaking in the Gross-Neveu
model at finite temperature, density and constant curvature. The effective
potential is evaluated in the leading order of the -expansion and in a
weak curvature approximation. The third order critical line is found on the
critical surface in the parameter space of temperature, chemical potential and
constant curvature.Comment: 11 pages, Latex. 3 figures (eps files
Yukawa Matrix for the Neutrino and Lepton Flavour Violation
We estimate the magnitude of Lepton Flavour Violation (LFV) from the phase of
the neutrino Yukawa matrix. In the minimal supersymmetric standard model with
right-handed neutrinos, the LFV processes l_i \to l_j \gamma can appear through
the slepton mixing, which comes from the renormalization group effect on the
right-handed neutrino Yukawa interaction between the Grand Unified Theory scale
and the heavy right-handed neutrino mass scale. Two types of phases exist in
the neutrino Yukawa matrix. One is the Majorana phase, which can change the
magnitude of the LFV branching ratios by a few factor. The other phases relate
for the size of the Yukawa hierarchy and its phase effect can change the LFV
branching ratios by several orders of magnitude.Comment: Talk given by K. Tsumura at NuFact04, Osaka, Japan, July 26 - August
1,2004 - 3 pages, 2 figure
Some aspects of radiative corrections and non-decoupling effects of heavy Higgs bosons in two Higgs Doublet Model
The possibility of having relatively large non-decoupling effects of the
heavy Higgs particles within the two-Higgs doublet extension of the electroweak
standard model is briefly discussed and demonstrated on an example of the
one-loop amplitude of the process e^+e^- -> W^+W^-Comment: 6 pages, 3 figures; to appear in the proceedings of the AM2003
conferenc
Bi-maximal mixing at GUT, the low energy data and the leptogenesis
In the framework of the minimum supersymmetric model with right-handed
neutrinos, we consider the Bi-maximal mixing which is realized at the GUT scale
and discuss a question that this model can reproduce the low energy phenomena
and the leptogenesis.Comment: Talk given by E. Takasugi at NuFact04, Osaka, Japan, July 26 - August
1,2004 - 3 pages, 4 figure
Enhancement of Loop Induced Vertex in Two Higgs-doublet Model
The non-decoupling effects of heavy Higgs bosons as well as fermions on the
loop-induced vertex are discussed in the general two Higgs
doublet model. The decay width of the process is calculated
at one-loop level and the possibility of its enhancement is explored both
analytically and numerically. We find that the novel enhancement of the decay
width can be realized by the Higgs non-decoupling effects with large
mass-splitting between the charged Higgs boson and the CP-odd one. This is due
to the large breakdown of the custodial invariance in the Higgs
sector. The branching ratio can amount to for GeV within the constraint from the present experimental data. Hence this
mode may be detectable at LHC or future linear colliders.Comment: 31+1 pages, Latex with 8 eps-file
Leptonic Charged Higgs Decays in the Zee Model
We consider the version of the Zee model where both Higgs doublets couple to
leptons. Within this framework we study charged Higgs decays. We focus on a
model with minimal number of parameters consistent with experimental neutrino
data. Using constraints from neutrino physics we (i) discuss the reconstruction
of the parameter space of the model using the leptonic decay patterns of both
of the two charged Higgses, , and the decay
of the heavier charged Higgs, ; (ii) show that the
decay rate in general is enhanced in
comparision to the standard two Higgs doublet model while in some regions of
parameter space even dominates over
.Comment: 25 pages, 9 figure
Phase effects from the general neutrino Yukawa matrix on lepton flavor violation
We examine contributions from Majorana phases to lepton flavor violating
processes in the framework of the minimal supersymmetric standard model with
heavy right-handed neutrinos. All phases in the complex neutrino Yukawa matrix
are taken into account in our study. We find that in the scenario with
universal soft-breaking terms sizable phase effects can appear on the lepton
flavor violating processes such as , , and
. In particular, the branching ratio of
can be considerably enhanced due to the Majorana phases, so that it can be much
greater than that of .Comment: 14 pages, 4 eps figures, revtex
Enhancement of lepton flavor violation in a model with bi-maximal mixing at the grand unification scale
We study phenomenological predictions in the scenario with the
quasi-degenerate relation among neutrino Dirac masses, m_D1 simeq m_D2 < m_D3,
assuming the bi-maximal mixing at the grand unification scale in supersymmetric
standard models with right-handed neutrinos. A sufficient lepton number
asymmetry can be produced for successful leptogenesis. The lepton flavor
violating process mu to e gamma can be enhanced due to the Majorana phase, so
that it can be detectable at forthcoming experiments. The processes tau to e
gamma and tau to mu gamma are suppressed because of the structure of neutrino
Dirac masses, and their branching ratios are smaller than that of mu to e
gamma.Comment: 15 pages, 5 figure
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