30,864 research outputs found
Lepton flavor violating processes in unparticle physics
We study the virtual effects of unparticle physics in the lepton flavor
violating processes and scattering, where
denotes the pseudoscalar mesons: and
denote two different lepton flavors. For the decay of , there
is no constraint from the current experimental upper bounds on the vector
unparticle coupling with leptons. The constraint on the coupling constant
between scalar unparticle field and leptons is sensitive to the scaling
dimension of the unparticle . For the scattering process , there is only constraint from experiments on the vector unparticle
couplings with leptons but no constraint on the scalar unparticle. We study the
dependence of the cross section of with different values of
. If , the cross section is independent on the
center mass energy. For , the cross section increases with
.Comment: 8 pages, revtex4,with 2 figures, to appear in Phys. Rev.
Oscillation in power spectrum of primordial gravitational wave as a signature of higher-order stringy corrections
In low-energy effective string theory, corrections involve the
coupling of the dilaton field to Gauss-Bonnet term. We assume that the dilaton
potential is fine tuned so that the dilaton field may oscillate rapidly for a
while around the minimum of its potential but the inflation background is not
affected. By numerical method, we find that if the dilaton starts to oscillate
at the time of about e-folds before the end of inflation,
correction may bring unusual oscillations to the inflationary
gravitational wave spectrum, which might be measurably imprinted in the CMB
B-mode polarization.Comment: 19 pages, 7 figures; published version in JHEP, many details
supplemented, including 3 appendixes and 1 figure; references and comments
added, presentation improve
Chirality oscillation of primordial gravitational waves during inflation
We show that if the gravitational Chern-Simons term couples to a massive
scalar field (), the primordial gravitational waves (GWs) will show itself
the chirality oscillation, i.e., the amplitudes of the left- and right-handed
GWs modes will convert into each other and oscillate in their propagations.
This oscillation will eventually develop a permanent difference of the
amplitudes of both modes, which leads to nearly opposite oscillating shapes in
the power spectra of the left- and right-handed primordial GWs. We discuss its
implication to the CMB B-mode polarization.Comment: 14 pages, 11 figures; published version in JHEP; one figure added;
references and comments adde
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