2,871 research outputs found
Horizontal symmetry in Higgs sector of GUT with U(1)_A symmetry
In a series of papers, we pointed out that an anomalous gauge
symmetry naturally solves various problems in grand unified theories (GUTs) and
that a horizontal gauge symmetry, or , not only realizes the
unification of three generation quarks and leptons in fewer multiplets but also
solves the supersymmetric flavor problem. In this paper, we examine the
possibility that the Higgs sectors of the GUT symmetry and of the horizontal
symmetry are unified, that is, there are some Higgs fields whose vacuum
expectation values (VEVs) break both the GUT gauge symmetry and the horizontal
symmetry at the same time. Although the scale of the VEVs become too large to
suppress the flavor changing neutral current processes sufficiently, the
unification is possible. In addition, for the models, the
gauge anomaly is cancelled in the unified models without introducing additional
fields in contrast with the previous models in which the Higgs sectors are not
unified.Comment: 35 page
Temperature dependence of spinon and holon excitations in one-dimensional Mott insulators
Motivated by the recent angle-resolved photoemission spectroscopy (ARPES)
measurements on one-dimensional Mott insulators, SrCuO and
NaVO, we examine the single-particle spectral weight
of the one-dimensional (1D) Hubbard model at half-filling. We are particularly
interested in the temperature dependence of the spinon and holon excitations.
For this reason, we have performed the dynamical density matrix renormalization
group and determinantal quantum Monte Carlo (QMC) calculations for the
single-particle spectral weight of the 1D Hubbard model. In the QMC data, the
spinon and holon branches become observable at temperatures where the
short-range antiferromagnetic correlations develop. At these temperatures, the
spinon branch grows rapidly. In the light of the numerical results, we discuss
the spinon and holon branches observed by the ARPES experiments on
SrCuO. These numerical results are also in agreement with the
temperature dependence of the ARPES results on NaVO.Comment: 8 pages, 8 figure
Gauge-mediated supersymmetry breaking with generalized messenger sector at LHC
We consider the generalized gauge mediated supersymmetry breaking (GMSB)
models with the messenger elds which do not form the complete multiplets of SU(5)
GUT symmetry. Such a situation may happen in the anomalous U(1) GUT scenario
because the mass spectrum of the superheavy particle does not respect SU(5) GUT
symmetry, although the success of the gauge coupling uni cation can be explained.
In this paper, we assume that one pair of the messenger elds gives the dominant
contribution, and the LHC signature for the two possible messengers, X + X and
Q + Q, are examined. We investigate the possibility to measure the deviation from
the usual GUT relation of the gaugino masses which is one of the most important
features of these scenarios.
1
Gauge Coupling Unification in GUT with Anomalous U(1) Symmetry
We show that in the framework of grand unified theory (GUT) with anomalous
gauge symmetry, the success of the gauge coupling unification in the
minimal SU(5) GUT is naturally explained, even if the mass spectrum of
superheavy fields does not respect SU(5) symmetry. Because the unification
scale for most realizations of the theory becomes smaller than the usual GUT
scale, it suggests that the present level of experiments is close to that
sufficient to observe proton decay via dimension 6 operators, .Comment: 4 pages, RevTeX, to appear in Phys.Rev.Let
Strength of the d_{x^2-y^2} pairing in the two-leg Hubbard ladder
In the ground state of the doped two-leg Hubbard ladder there are power-law
decaying d_{x^2-y^2}-type pairing correlations. It is important to know the
strength and the temperature scale of these correlations. For this purpose, we
have performed determinantal Quantum Monte Carlo (QMC) calculations of the
reducible particle-particle interaction in the Hubbard ladder. In this paper,
we report on these calculations and show that, at sufficiently low
temperatures, resonant particle-particle scattering takes place in the
d_{x^2-y^2} pairing channel for certain values of the model parameters. The QMC
data presented here indicate that the d_{x^2-y^2} pairing correlations are
strong in the Hubbard ladder.Comment: 5 pages, 5 figure
Sliding Singlet Mechanism Revisited
We show that the unification of the doublet Higgs in the standard model (SM)
and the Higgs to break the grand unified theory (GUT) group stabilizes the
sliding singlet mechanism which can solve the doublet-triplet (DT) splitting
problem. And we generalize this attractive mechanism to apply it to many
unified scenarios. In this paper, we try to build various concrete E_6 unified
models by using the generalized sliding singlet mechanism.Comment: 13 page
CEDM constraints on modified sfermion universality and spontaneous CP violation
We discuss the supersymmetric CP problem that arises when the sfermion soft
mass universality is modified. We place the 3rd generation SU(5) ten-plet
sfermion masses in the weak scale in view of the naturalness. The other
sfermion masses are assumed to be universal and a TeV scale in order to weaken
the flavor changing neutral current processes and electric dipole moment (EDM)
constraints. However this modification generically induces too large up quark
chromo-EDM (CEDM) via the weak scale stop loop. In order to suppress this CEDM,
we propose certain type of flavor structure where the parameters of the
up-(s)quark sector are real whereas those of the down-(s)quark and the charged
(s)lepton sectors are complex at the GUT scale. It is shown that, in this set
up, up quark CEDM can be suppressed within the range where the current and
future experiments have their sensitivity. We briefly illustrate the simple
realization of these particular forms of the modified sfermion universality
with real up-(s)quark sector by spontaneous CP violation in E SUSY GUT with
SU(2) flavor symmetry.Comment: Hg EDM bound updated, content modified, figure added, typos
corrected, references adde
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