3,609 research outputs found
Higgs--mediated K -> pi nu nu-bar in the MSSM at large tan(beta)
We analyze the impact of Higgs-mediated amplitudes on the rare decays KL ->
pi0 nu nu-bar and K+ -> pi+ nu nu-bar in the MSSM with large tan(beta) and
general flavour mixing. We point out that, going beyond the minimal flavour
violation hypothesis, Z-penguin amplitudes generated by charged-Higgs exchange
can induce sizable modifications of K -> pi nu nu-bar rates. Interestingly,
these effects scale as tan^4(beta) at the amplitude level. For large values of
tan(beta), this mechanism allows deviations from the SM expectations even for
tiny (CKM-type) off-diagonal mixing terms in the right-handed squark sector.Comment: 9 pages, 2 figure
Radiative Non-Leptonic Kaon Decays
We investigate to what extent DANE will be able to test the Standard
Model in the confinement regime with radiative kaon decays. We concentrate on
processes which can be detected at DANE and we review briefly those
decays where only upper limits can be expected. The Standard Model predictions
for these decays are analyzed in the framework of chiral perturbation theory.Comment: 41 pages, latex file, 10 figures added in a separate uufil
Electromagnetism in nonleptonic weak interactions
We construct a low-energy effective field theory that permits the complete
treatment of isospin-breaking effects in nonleptonic weak interactions to
next-to-leading order. To this end, we enlarge the chiral Lagrangian describing
strong and Delta S=1 weak interactions by including electromagnetic terms with
the photon as additional dynamical degree of freedom. The complete and minimal
list of local terms at next-to-leading order is given. We perform the one-loop
renormalization at the level of the generating functional and specialize to K
-> pi pi decays.Comment: 17 pages, 1 figure; 2 references added, final version for publication
in Nucl. Phys.
The rare decay B --> X_s l^+ l^- to NNLL precision for arbitrary dilepton invariant mass
We present a new phenomenological analysis of the inclusive rare decay . In particular, we present the first calculation of the NNLL
contributions due to the leading two-loop matrix elements, evaluated for
arbitrary dilepton invariant mass. This allows to obtain the first NNLL
estimates of the dilepton mass spectrum and the lepton forward-backward
asymmetry in the high region, and to provide an
independent check of previously published results in the low region. The numerical impact of these NNLL corrections in the
high-mass region () amounts to -13% in the
integrated rate, and leads to a reduction of the scale uncertainty to .
The impact of non-perturbative contributions in this region is also discussed
in detail.Comment: 40 pages, 12 figures. v2: extended phenomenological discussion;
results unchanged; published versio
Direct CP violation in K->3pi decays induced by SUSY chromomagnetic penguins
An analysis of the CP violating asymmetry in decays in
the Standard Model and, by means of the mass insertion approximation, in a wide
class of possible supersymmetric extensions, is presented. We find that the
natural order of magnitude for this asymmetry is \cO(10^{-5}) in both cases.
Within supersymmetric models effects as large as \cO(10^{-4}) are possible,
but only in a restricted range of the relevant parameters.Comment: Latex, 11 pages, 1 figur
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