218 research outputs found

### Direct CP violation in $D^+ \to K^0(\bar K^0) \pi^+$ decays as a probe for new physics

In this paper we investigate CP violation in charged decays of $D$ meson.
Particularly, we study the direct CP asymmetry of the Cabibbo favored
non-leptonic $D^+ \rightarrow \bar K^0 \pi^+$ and the doubly Cabibbo-suppressed
decay mode $D^+ \rightarrow K^0 \pi^+$ within standard model, two Higgs doublet
model with generic Yukawa structure and left right symmetric models. In the
standard model, we first derive the contributions from box and di-penguin
diagrams contributing to their amplitudes which are relevant to the generation
of the weak phases essential for non-vanishing direct CP violation. Then, we
show that these phases are so tiny leading to a direct CP asymmetry of order
$10^{-11}$ in both decay modes. Regarding the two Higgs doublet model with
generic Yukawa structure and after taking into account all constraints on the
parameter space of the model, we show that the enhanced direct CP asymmetries
can be 6 and 7 orders of magnitudes larger than the standard model prediction
for $D^+ \rightarrow \bar K^0 \pi^+$ and $D^+ \rightarrow K^0 \pi^+$
respectively. Finally, within left right symmetric models, we find that sizable
direct CP asymmetry of ${\mathcal O } (10^{-3})$ can be obtained for the decay
mode $D^+ \rightarrow \bar K^0 \pi^+$ after respecting all relevant
constraints.Comment: 20 pages, 2 figures. arXiv admin note: text overlap with
arXiv:1710.0041

### A new strategy for probing the Majorana neutrino CP violating phases and masses

We propose a new strategy for detecting the CP-violating phases and the
effective mass of muon Majorana neutrinos by measuring observables associated
with neutrino-antineutrino oscillations in $\pi^{\pm}$ decays. Within the
generic framework of quantum field theory, we compute the non-factorizable
probability for producing a pair of same-charged muons in $\pi^{\pm}$ decays as
a distinctive signature of $\nu_{\mu}-\bar{\nu_{\mu}}$ oscillations. We show
that an intense neutrino beam through a long baseline experiment is favored for
probing the Majorana phases. Using the neutrino-antineutrino oscillation
probability reported by MINOS collaboration, a new stringent bound on the
effective muon-neutrino mass is derived.Comment: 4 pages, 1 figur

### Supersymmetric contribution to B to rho K and B to pi K^* decays in SCET

We analyze the supersymmetric contributions to the direct CP asymmetries of
the decays $B \to \pi K^*$ and $B\to\rho K$ within Soft Collinear Effective
Theory. We extend the Standard Model analysis of these asymmetries to include
the next leading order QCD corrections. We find that, even with QCD correction,
the Standard Model predictions can not accommodate the direct CP asymmetries in
these decay modes. Using Mass Insertion Approach, we show that non-minimal
flavor SUSY contributions mediated by gluino exchange can enhance the CP
asymmetries significantly and thus can accommodate the experimental results.Comment: 12 pages, 5 figures, version to appear in PL

### Complex Hybrid Inflation and Baryogenesis

We propose a hybrid inflation model with a complex waterfall field which
contains an interaction term that breaks the U(1) global symmetry associated to
the waterfall field charge. We show that the asymmetric evolution of the real
and imaginary parts of the complex field during the phase transition at the end
of inflation translates into a charge asymmetry. The latter strongly depends on
the vev of the waterfall field, which is well constrained by diverse
cosmological observations.Comment: 4 RevTex pages, no figures. Changes made in response to referee's
comments; matches version published in Phys.Rev.Let

### Neutrino Mixing and the Pattern of Supersymmetry Breaking

We study the implications of a large $\nu_\mu - \nu_\tau$ mixing angle on
lepton flavour violating radiative transitions in supersymmetric extensions of
the standard model. The transition rates are calculated to leading order in
$\epsilon$, the parameter which characterizes the flavour mixing. The
uncertainty of the predicted rates is discussed in detail. For models with
modular invariance the branching ratio $BR(\mu \to e \gamma)$ mostly exceeds
the experimental upper limit. In models with radiatively induced flavour mixing
the predicted range includes the upper limit, if the Yukawa couplings in the
lepton sector are large, as favoured by Yukawa coupling unification.Comment: 12 pages, 2 figures, used axodraw.sty, to be published in Physics
Letters

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