10,628 research outputs found
Probing New Physics From CP Violation in Radiative B Decays
When new CP-violating interactions are dominated by flavor changing neutral
particle exchanges, that may occur in many extensions of the standard model. We
examine a type 3 two Higgs doublet model and find that direct CP asymmetries
can be as large as about 25% . Time-dependent and time-integrated
mixing-induced CP asymmetries up to 85 and 40 %, respectively, are possible
without conflict with other constraints. It mainly requirs an enhanced
chromo-magnetic dipole decay to be close to the present experimental
bound.Comment: 7 pages, latex, no figure
Beyond the Standard Model in B Decays: Three Topics
Three new results are discussed: (a) A non-vanishing amplitude for the `wrong
sign{'} kaon decay or its CP conjugate is shown to be a
necessary condition for obtaining different CP asymmetries in . A significant effect would require a scale of new physics far below
the weak scale, all but ruling out this possibility. (b) The leading isospin
breaking contributions to the decay amplitudes can be
calculated in QCD factorization, providing a sensitive probe of the penguin
sector of the effective weak Hamiltonian. New physics models which reverse the
predicted Standard Model amplitude hierarchy could be ruled out with
more precise data. (c) A slowly falling form factor can be
ruled out using the spectrum obtained by ARGUS at the . The decay is therefore highly suppressed and the
origin of the anomalously large rate remains unknown,
perhaps requiring the intervention of New Physics.Comment: 12 pages, 3 figure
Formation of a condensed state with macroscopic number of phonons in ultracold Bose gases
A mechanism for the formation of a new type of stationary state with
macroscopical number of phonons in condensed atomic gases is proposed. This
mechanism is based on generating longitudinal phonons as a result of parametric
resonance caused by a permanent modulation of the transverse trap frequency in
an elongated trap. The phonon-phonon interaction predetermines the
self-consistent evolution which is completed with macroscopic population of one
from all levels within the energy interval of parametric amplification. This
level proves to be shifted to the edge of this interval. All other levels end
the evolution with zero population.Comment: 9 pages, 8 figure
Family nonuniversal Z-prime and b to s Gamma decay
We have calculated the branching ratio and CP asymmetry of B-->X_s +gamma
decay within the family--nonuniversal Z' models. We have established certain
bounds on the model parameters using the present experimental bounds. We also
comment on the role of family--nonuniversality in the hadronic decay modes of
the B meson.Comment: 15 pages, 2 figure
The top squark-mediated annihilation scenario and direct detection of dark matter in compressed supersymmetry
Top squark-mediated annihilation of bino-like neutralinos to top-antitop
pairs can play the dominant role in obtaining a thermal relic dark matter
abundance in agreement with observations. In a previous paper, it was argued
that this can occur naturally in models of compressed supersymmetry, which
feature a running gluino mass parameter that is substantially smaller than the
wino mass parameter at the scale of apparent gauge coupling unification. Here I
study in some more detail the parameter space in which this is viable, and
compare to other scenarios for obtaining the observed dark matter density. I
then study the possibility of detecting the dark matter directly in future
experiments. The prospects are consistently very promising for a wide variety
of model parameters within this scenario.Comment: 17 pages. v2: additions to figures 4 and
Manifestation of superfluidity in an evolving Bose-condensed gas
We study the generation of excitations due to an ''impurity''(static
perturbation) placed into an oscillating Bose-condensed gas in the
time-dependent trapping field. It is shown that there are two regions for the
position of the local perturbation. In the first region the condensate flows
around the ''impurity'' without generation of excitations demonstrating
superfluid properties. In the second region the creation of excitations occurs,
at least within a limited time interval, revealing destruction of
superfluidity. The phenomenon can be studied by measuring the damping of
condensate oscillations at different positions of the ''impurity''
Testing for new physics in singly Cabibbo suppressed D decays
We devise tests for a new physics origin of the recently measured direct CP
violation in singly Cabibbo suppressed D decays. The tests take the form of sum
rules for the CP asymmetries in various D decays. They are based on the fact
that within the standard model CP violation arises from interference of the
dominant tree amplitudes with the Delta I=1/2 penguin amplitudes. The sum rules
would be violated if the observed CP violation is due to new physics
contributions to the effective weak Hamiltonian that change isospin by Delta
I=3/2.Comment: 6 page
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