5,208 research outputs found
Like-sign dimuon charge asymmetry in Randall-Sundurm model
We confirm that in order to account for the recent D\O\ result of large
like-sign dimuon charge asymmetry, a considerable large new physics effect in
is required in addition to a large CP violating phase in mixing. In the Randall-Sundrum model of warped geometry, where the
fermion fields reside in the bulk, new sources of flavor and CP violation are
obtained. We analyze the like-sign dimuon asymmetry in this class of model, as
an example of the desired new physics. We show that the wrong charge asymmetry,
, which is related to the dimuon asymmetry, is significantly altered
compared to the Standard Model value. However, experimental limits from , as well as mixing and electroweak corrections
constrain it to be greater than a away from its experimental average
value. This model cannot fully account for the D\O\ anomaly due to its
inability to generate sufficient new contribution to the width difference
, even though the model can generate large contribution to the
mass difference .Comment: 20 pages, 9 figures, discussions and references added, accepted for
publication in Physical Review
On supersymmetric contributions to the CP asymmetry of the B -> phi K_S
We analyse the CP asymmetry of the B -> phi K_S process in general
supersymmetric models. In the framework of the mass insertion approximation, we
derive model independent limits for the mixing CP asymmetry. We show that
chromomagnetic type of operator may play an important role in accounting for
the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi
K_S processes observed by Belle and BaBar experiments. A possible correlation
between the direct and mixing CP asymmetry is also discussed. Finally, we apply
our result in minimal supergravity model and supersymmetric models with
non-universal soft terms.Comment: 19 pages, 3 figure
Gauging U(1) symmetries and the number of right-handed neutrinos
In this letter we consider that assuming: a) that the only left-handed
neutral fermions are the active neutrinos, b) that is a gauge symmetry,
and c) that the assignment is restricted to the integer numbers, the
anomaly cancellation imply that at least three right-handed neutrinos must be
added to the minimal representation content of the electroweak standard model.
However, two types of models arise: i) the usual one where each of the three
identical right-handed neutrinos has total lepton number L=1; ii) and the other
one in which two of them carry L=4 while the third one carries .Comment: Published version in PLB forma
The Puzzle and Supersymmetric Models
In the light of new experimental results on decays, we study the
decay processes in the framework of both R-parity conserving
(SUGRA) and R-parity violating supersymmetric models. We find that any possible
deviations from the Standard Model indicated by the current data for the
branching ratios and the direct CP asymmetries of can be explained
in both R-parity conserving SUGRA and R-parity violating SUSY models. However,
there is a difference between the predictions of both models to the
time-dependent CP asymmetry observable whose current
experimental results include large uncertainties. We demonstrate that this
difference can be useful for testing both models with more accurate data for
and in the near future.Comment: 14 pages, 3 figure
Implication of scalar-pseudoscalar mixing on in SUSY models
We study the effects of scalar-pseudoscalar mixing induced from quantum loop
on in SUSY models with . We
find that even the non-universal soft term and Yukawa matrix,
, are hermitian, the predicted value of can be
consistent with the measured results of NA48 and KTeV. And also the EDMs are
compatible with experimental bounds.Comment: 11 pages, 1 figure, one typo corrected, to appear in Phys. Lett.
A solution to B --> pi pi puzzle and B --> K K
The large ratio of color-suppressed tree amplitude to color-allowed one in decays is difficult to understand within the Standard Model, which
is known as the " puzzle". The two tree diagrams contain the up-
and charm-quark component of penguin amplitude, , which cannot be
separated by measuring decays alone. We show that the
measurements of the branching ratio and direct CP asymmetry of decay enable one to disentangle the with two-fold
ambiguity. One of the two degenerate solutions of the can solve the puzzle by giving which is consistent with the
expectation in the Standard Model. We also show that the two solutions can be
discriminated by the measurement of the indirect CP-asymmetry of B^0 \to K^0
\ol{K^0}. We point out that if the puzzle is solved in this
way, the corresponding puzzle in decays should have a different
origin.Comment: 12 pages, 2 figures, minor changes, references adde
First Lattice Calculation of the Electromagnetic Operator Amplitude <pi0|Q+|K0>
We present the first lattice calculation of the matrix element of the
electromagnetic operator , where Q+ = (Q_d e/16 pi^2)* (\bar s_L
sigma{mu,nu} F{mu,nu} d_R + \bar s_R sigma{mu,nu} F{mu,nu} d_L). This matrix
element plays an important role, since it contributes to enhance the CP
violating part of the K_L -> pi0 e+ e- amplitude in supersymmetric extensions
of the Standard Model.Comment: 12 pages, 3 figure
New Source of CP violation in B physics ?
In this talk we discuss how the down type left-right squark mixing in
Supersymmetry can induce a new source of CP violation in the time dependent
asymmtries in B --> phi K process. We use QCD improved factorization process to
calculate the hadronic matrix element for the process and find the allowed
parameter space for and , the magnitude and phase of the down
type LR(RL) squark mixing parameter . In the same allowed
regin we calculate the expected CP asymmtries in the
process.Comment: 16 pages, Latex, 2 postscript figures, invited talk presented by N.G.
Deshpande at the 9th Adriatic meeting, Dubrovnik, Croatia, 4-14 September,
2003. With updated reference
Fully supersymmetric CP violations in the kaon system
We show that, on the contrary to the usual claims, fully supersymmetric CP
violations in the kaon system are possible through the gluino mediated flavor
changing interactions. Both and can be accommodated for relatively large without any
fine tunings or contradictions to the FCNC and EDM constraints.Comment: Contribution to the Proceedings of ICHEP2000, Osaka, 200
Parameters in a Class of Leptophilic Dark Matter Models from PAMELA, ATIC and FERMI
In this work we study a class of leptophilic dark matter models, where the
dark matter interacts with the standard model particles via the
gauge boson, to explain the excess in cosmic rays
observed by ATIC and PAMELA experiments, and more recently by Fermi experiment.
There are three types of models: a) , b)
, and c) . Although ATIC or Fermi
data is consistent with PAMELA data separately, ATIC and Fermi data do not
agree with each other. We therefore aim to identify which of the three models
can explain which data set better. We find that models a) and b) can give
correct dark matter relic density and explain the ATIC and PAMELA data
simultaneously recur to the Breit-Wigner enhancement. Whereas model c) with a
larger mass can explain Fermi and PAMELA data simultaneously. In all
cases the model parameters are restricted to narrow regions. Future improved
data will decide which set of data are correct and also help to decide the
correct dark matter model.Comment: Latex 15 pages with 5 figures. Modified to include discussions of
recent Fermi data on the leptophilic models studied in this paper. Title also
modifie
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