18 research outputs found
Radion Flavor Violation in Warped Extra Dimension
We analyze the flavor violation in warped extra dimension due to radion
mediation. We show that \Delta S=2 and \Delta B=2 flavor violating processes
impose stringent constraints on radion mass, m_\phi and the scale \Lambda_\phi.
In particular, for \Lambda_\phi ~ O(1) TeV, B_d^0-\bar{B}^0_d implies that
m_\phi ~ 65 GeV. We also study radion contributions to lepton flavor violating
processes: \tau -> (e,\mu) \phi, \tau -> e\mu^+\mu^- and B -> l_i l_j. We show
that BR(B_s -> \mu^+ \mu^-) can be of order 10^{-8}, which is reachable at the
LHCb. The radion search at LHC, through the flavor violation decays into \tau
\mu or top-charm quarks, is also considered.Comment: 23 pages, 9 figure
Signatures for doubly-charged Higgsinos at colliders
Several supersymmetric models with extended gauge structures predict light
doubly-charged Higgsinos. Their distinctive signature at the large hadron
collider is highlighted by studying their production and decay characteristics.Comment: 3 pages, 4 figures, Latex. Submitted for SUSY 2008 proceeding
Sterile neutrino dark matter in extension of the standard model and galactic 511 keV line
Sterile right-handed neutrinos can be naturally embedded in a low scale
gauged extension of the standard model. We show that, within a low
reheating scenario, such a neutrino is an interesting candidate for dark
matter. We emphasize that if the neutrino mass is of order of MeV, then it
accounts for the measured dark matter relic density and also accommodates the
observed flux of 511 keV photons from the galactic bulge.Comment: 10 pages, 1 figure, references added, final version appeared in JCA
Unparticle Searches Through Compton Scattering
We investigate the effects of unparticles on Compton scattering, e gamma -> e
gamma based on a future e^+e^- linear collider such as the CLIC. For different
polarization configurations, we calculate the lower limits of the unparticle
energy scale Lambda_U for a discovery reach at the center of mass energies
sqrt(s)=0.5 TeV- 3 TeV. It is shown that, especially, for smaller values of the
mass dimension d, (1 <d <1.3), and for high energies and luminosities of the
collider these bounds are very significant. As a stringent limit, we find
Lambda_U>80 TeV for d<1.3 at sqrt(s)=3 TeV, and 1 ab^(-1) integrated luminosity
per year, which is comparable with the limits calculated from other low and
high energy physics implications.Comment: Table 1 and 2 have been combined as Table 1, references updated,
minor typos have been correcte
Constraints from Solar and Reactor Neutrinos on Unparticle Long-Range Forces
We have investigated the impact of long-range forces induced by unparticle
operators of scalar, vector and tensor nature coupled to fermions in the
interpretation of solar neutrinos and KamLAND data. If the unparticle couplings
to the neutrinos are mildly non-universal, such long-range forces will not
factorize out in the neutrino flavour evolution. As a consequence large
deviations from the observed standard matter-induced oscillation pattern for
solar neutrinos would be generated. In this case, severe limits can be set on
the infrared fix point scale, Lambda_u, and the new physics scale, M, as a
function of the ultraviolet (d_UV) and anomalous (d) dimension of the
unparticle operator. For a scalar unparticle, for instance, assuming the
non-universality of the lepton couplings to unparticles to be of the order of a
few per mil we find that, for d_UV=3 and d=1.1, M is constrained to be M >
O(10^9) TeV (M > O(10^10) TeV) if Lambda_u= 1 TeV (10 TeV). For given values of
Lambda_u and d, the corresponding bounds on M for vector [tensor] unparticles
are approximately 100 [3/Sqrt(Lambda_u/TeV)] times those for the scalar case.
Conversely, these results can be translated into severe constraints on
universality violation of the fermion couplings to unparticle operators with
scales which can be accessible at future colliders.Comment: 13 pages, 3 figures. Minor changes due to precision in numerical
factors and correction in figure labels. References added. Conclusions remain
unchange
Constraints on Astro-unparticle Physics from SN 1987A
SN 1987A observations have been used to place constraints on the interactions
between standard model particles and unparticles. In this study we calculate
the energy loss from the supernovae core through scalar, pseudo scalar, vector,
pseudo vector unparticle emission from nuclear bremsstrahlung for degenerate
nuclear matter interacting through one pion exchange. In order to examine the
constraints on we considered the emission of scalar, pseudo
scalar, vector, pseudo vector and tensor through the pair annihilation process
. In addition we have re-examined other pair
annihilation processes. The most stringent bounds on the dimensionless coupling
constants for and are obtained from
nuclear bremsstrahlung process for the pseudo scalar and pseudo-vector
couplings and for
tensor interaction, the best limit on dimensionless coupling is obtained from
and we get .Comment: 12 pages, 2 postscript figure
B decays and Supersymmetry
I discuss how supersymmetry affects various observables in B decays, and
point out the interesting channels in the context of B factories.Comment: LaTex file of working group talk presented at WHEPP-7, HRI,
Allahabad, Jan. 200
Supersymmetric effects on Forward Backward asymmetries of
Leptonic and semi-leptonic rare decays of B-mesons are very clean (both
theoretically and experimentally) signatures of any new physics beyond the
Standard Model (SM). More specifically the decay \btokll has been theoretically
observed to be very sensitive to new physics as the Forward Backward (FB)
asymmetry in this decay mode vanishes in the SM. Supersymmetry, however,
predicts a non-vanishing value of this asymmetry. In this work we will study
the polarized lepton pair FB asymmetry, i.e. the FB asymmetry of the lepton
when one (or both) final state lepton(s) are polarized. We will study these
asymmetries both within the SM and for Supersymmetric corrections to the SM.Comment: 18 pages, RevTeX file including 21 eps figures; version accepted for
publication in Phys. Rev. D. Some references adde