7,421 research outputs found
Gravitational field equations in a braneworld with Euler-Poincare term
We present the effective gravitational field equations in a 3-brane world
with Euler-Poincare term and a cosmological constant in the bulk spacetime. The
similar equations on a 3-brane with symmetry embedded in a five
dimensional bulk spacetime were obtained earlier by Maeda and Torii using the
Gauss-Coddazzi projective approach in the framework of the Gaussian normal
coordinates. We recover these equations on the brane in terms of differential
forms and using a more general coordinate setting in the spirit of Arnowitt,
Deser and Misner (ADM). The latter allows for acceleration of the normals to
the brane surface through the lapse function and the shift vector. We show that
the gravitational effects of the bulk space are transmitted to the brane
through the projected ``electric'' 1-form field constructed from the conformal
Weyl curvature 2-form of the bulk space. We also derive the evolution equations
into the bulk space for the electric 1-form field, as well as for the
``magnetic'' 2-form field part of the bulk Weyl curvature 2-form. As expected,
unlike on-brane equations, the evolution equations involve terms determined by
the nonvanishing acceleration of the normals in the ADM-type slicing of
spacetime
Exclusive B -> K^* l^+ l^- decay with polarized K^* and new physics effects
Using the most general, model independent effective Hamiltonian, the
branching ratio of the (B -> K^* l^+ l^-) decay, when K^* meson is
longitudinally or transversally polarized, is presented. The dependence of the
branching ratio on the new Wilson coefficients, when K^* meson is polarized, is
studied. It is observed that the branching ratio is very sensitive to the
vector and tensor type interactions, which will be useful in search of new
physics beyond the Standard Model.Comment: 13 pp, 6 figures (postscript formatted), LaTex formatte
Exact metric around a wiggly cosmic string
The exact metric around a wiggly cosmic string is found by modifying the
energy momentum-tensor of a straight infinitely thin cosmic string to include
an electric current along the symmetry axis.Comment: 5 page
General analysis of time evolution of decay spectrum in B^0 -> pi^+ pi^- l^+ l^-
Using the general, model independent form of effective Hamiltonian, the decay
spectrum of B^0 -> pi^+ pi^- l^+ l^- decay is studied. The sensitivity of
experimentally measurable asymmetries to the new Wilson coefficients and time
is studied. It is observed that different asymmetries are sensitive to the new
Wilson coefficients and they can serve as an efficient tool for establishing
new physics beyond SM.Comment: 15 pp, 4 figures (postscript formatted), LaTex formatte
Semileptonic decays of pseudoscalar mesons to scalar "f_0" meson
The transition form factors of (D_s -> f_0 l nu), (D -> f_0 l nu) and (B_u ->
f_0 l nu) decays are calculated in 3-point QCD sum rule method, assuming that
"f_0" is a quark-antiquark state with a mixture of strange and light quarks.
The branching ratios of these decays are calculated in terms of the mixing
angle.Comment: 12 pages, 4 figures, LaTeX formatte
T violation in (Lambda_b -> Lambda l^+ l^-) decay beyond standard model
Using the most general, model independent form of effective Hamiltonian, the
transverse polarization P_T of Lambda in Lambda_b -> Lambda l^+ l^- decay is
studied. It is observed that the averaged is very sensitive to the
existence of new physics and can attain large values, which can be measured at
future colliders.Comment: 12 pages, 7 figures, LaTeX formatte
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