2,281 research outputs found
Finite Higgs mass without Supersymmetry
We identify a class of chiral models where the one-loop effective potential
for Higgs scalar fields is finite without any requirement of supersymmetry. It
corresponds to the case where the Higgs fields are identified with the
components of a gauge field along compactified extra dimensions. We present a
six dimensional model with gauge group U(3)xU(3) and quarks and leptons
accomodated in fundamental and bi-fundamental representations. The model can be
embedded in a D-brane configuration of type I string theory and, upon
compactification on a T^2/Z_2 orbifold, it gives rise to the standard model
with two Higgs doublets.Comment: 28 pages, 4 figures, uses axodraw. Some typos corrected and
references rearrange
Tensor mesons produced in tau lepton decays
Light tensor mesons (T = a_2, f_2 and K_2^*) can be produced in decays of tau
leptons. In this paper we compute the branching ratios of tau --> T pi nu
decays by assuming the dominance of intermediate virtual states to model the
form factors involved in the relevant hadronic matrix element. The exclusive
f_2(1270) pi^- decay mode turns out to have the largest branching ratio, of
O(10^-4) . Our results indicate that the contributions of tensor meson
intermediate states to the three-pseudoscalar channels of tau decays are rather
small.Comment: 10 pages, 1 figure. Version accepted for publication in PRD, some
typos are corrected and comments are added in section 4. Conclusions remain
unchange
EXPERIMENTAL STUDY ON UTILIZATION OF FOOD BY YOUNG ANCHOVY, ENGRAULIS JAPONICUS TEMMINCK et SCHLEGEL
Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States
We study the radiative and semileptonic B decays involving a spin-
resonant with parity for and for
in the final state. Using the large energy effective theory (LEET)
techniques, we formulate transition form factors in the large
recoil region in terms of two independent LEET functions
and , the values of
which at zero momentum transfer are estimated in the BSW model. According to
the QCD counting rules, exhibit a dipole
dependence in . We predict the decay rates for ,
and . The
branching fractions for these decays with higher -resonances in the final
state are suppressed due to the smaller phase spaces and the smaller values of
. Furthermore, if the spin of
becomes larger, the branching fractions will be further suppressed due to the
smaller Clebsch-Gordan coefficients defined by the polarization tensors of the
. We also calculate the forward backward asymmetry of the decay, for which the zero is highly insensitive to the
-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title
and references revise
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
Radiative and Semileptonic B Decays Involving the Tensor Meson K_2^*(1430) in the Standard Model and Beyond
We study semileptonic and radiative B decays involving the strange tensor
meson K_2^*(1430) in the final state. Using the large energy effective theory
(LEET) techniques, we formulate the B \to K_2^* transition form factors in
large recoil region. All the form factors can be parametrized in terms of two
independent LEET parameters \zeta_\perp and \zeta_\parallel. The magnitude of
\zeta_\perp is estimated from the data for Br(B \to K_2^*(1430)\gamma).
Assuming a dipole q^2-dependence for the LEET parameters and
\zeta_\parallel/\zeta_\perp = 1.0 \pm 0.2, we investigate the decays B \to
K_2^* \ell^+ \ell^- and B \to K_2^* \nu \bar{\nu}, where the contributions due
to $\zeta_\parallel are suppressed by m_{K_2^*}/m_B. For the B \to K_2^* \ell^+
\ell^- decay, in the large recoil region where the hadronic uncertainties are
considerably reduced, the longitudinal distribution d F_L/ds is reduced by
20-30 % due to the flipped sign of c_7^eff compared with the standard model
result. Moreover, the forward-backward asymmetry zero is about 3.4 GeV^2 in the
standard model, but changing the sign of c_7^eff yields a positive asymmetry
for all values of the invariant mass of the lepton pair. We calculate the
branching fraction for B \to K_2^* \nu \bar{\nu} in the standard model. Our
result exhibits the impressed resemblance between B \to K_2^*(1430)
\ell^+\ell^-, \nu \bar{\nu} and B \to K^*(892) \ell^+ \ell^-, \nu\bar{\nu}.Comment: 21 pages, 4 figures (v2) comments adde
Extranatural Inflation
We present a new model of inflation in which the inflaton is the extra
component of a gauge field in a 5d theory compactified on a circle. The chief
merit of this model is that the potential comes only from non-local effects so
that its flatness is not spoiled by higher dimensional operators or quantum
gravity corrections. The model predicts a red spectrum (n ~ 0.96) and a
significant production of gravitational waves (r ~ 0.11). We also comment on
the relevance of this idea to quintessence.Comment: 4 pages. Minor corrections and references added. Accepted for PR
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