6,008 research outputs found
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
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
Double-lepton polarizations in (B -> l^+ l^- gamma) decay
Double-lepton polarization asymmetries in the (B -> l^+ l^- gamma) decay are
calculated using the most general, model independent form of the effective
Hamiltonian including all possible forms of the interaction. The dependencies
of the asymmetries on new Wilson coefficients are investigated. The
detectability the averaged double-lepton polarization asymmetries at LHC is
also discussed.Comment: 20 pages, 7 PostScript figures, LaTeX formatte
Octet baryon magnetic moments in light cone QCD sum rules
Octet baryon magnetic moments are calculated in framework of the light cone
QCD sum rules. The analysis is carried for the general form of the
interpolating currents for octet baryons. A comparison of our results on the
magnetic moments of octet baryons with the predictions of other approaches and
experimental data is presented.Comment: 20 pages, 10 figures, 1 Table, 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
Fourth generation effects in processes induced by "b -> s" transition
We study the effects of sequential fourth quark generation in rare "B ->
K(K*) l^+ l^-" decays induced by "b -> s" transition and in "B_s^0 -
bar{B}_s^0" mixing. Using the experimental values on branching ratios of the "B
-> X_s gamma" and "B -> K(K*) l^+ l^-" decays, the allowed regions for \vel
V_{tb} V_{ts}^\ast\ver and "|V_{t'b} V_{t's}*| are determined as a function of
the (t') quark mass.Comment: 18 pages, 8 figures, LaTeX formatte
Radiative (phi -> f_0(980) gamma) decay in light cone QCD sum rules
The light cone QCD sum rules method is used to calculate the transition form
factor for the radiative (phi -> f_0 gamma) decay, assuming that the quark
content of the (f_0) meson is pure (bar{s}s) state. The branching ratio is
estimated to be Br(phi -> f_0 gamma) = 3.5 x (1 pm 0.3) x 10^(-4). A comparison
of our prediction on branching ratio with the theoretical results and
experimental data existing in literature is presented.Comment: 8 pp, 1 figure (postscript formatted), LaTex formatte
Mixing Angle of Hadrons in QCD: A New View
A new method for calculation of the mixing angle between the hadrons within
QCD sum rules is proposed. In this method, the mixing is expressed in terms of
quark and gluon degrees of freedom. As an application, the detailed calculation
of the mixing angle between heavy cascade baryons Xi_Q and Xi_Q', Q=c,~b is
presented and it is found that the mixing angle between Xi_b (Xi_c) and Xi_b'
(Xi_c') is given by theta_b = 6.4^\circ \pm 1.8 ^\circ (theta_c = 5.5^\circ \pm
1.8^\circ).Comment: 10 pages, 4 figures, 1 table, Changes in the text onl
- …