8,166 research outputs found
Neutrino masses and R-parity violation
We review different contributions to the neutrino masses in the context of
R-parity violating supersymmetry in a basis independent manner. We comment on
the generic spectrum expected in such a scenario comparing different
contributions.Comment: Invited brief review for Mod. Phys. Lett. A, 15 pages, uses
axodraw.st
Fast CP Violation
flavor tagging will be extensively studied at the asymmetric
factories due to its importance in CP asymmetry measurements. The primary
tagging modes are the semileptonic decays of the (lepton tag), or the
hadronic decays (kaon tag). We suggest that looking for time
dependent CP asymmetries in events where one is tagged leptonically and the
other one is tagged with a kaon could result in an early detection of CP
violation. Although in the Standard Model these asymmetries are expected to be
small, , they could be measured with about the same amount of data as
in the ``gold-plated'' decay . In the presence of physics
beyond the Standard Model, these asymmetries could be as large as ,
and the first CP violation signal in the system may show up in these
events. We give explicit examples of new physics scenarios where this occurs.Comment: 9 pages, revtex, no figures. Discussion of new physics effects on CP
violation with two lepton tags expanded. Factors of 2 correcte
The CKM matrix and CP Violation
The status of CP violation and the CKM matrix is reviewed. Direct CP
violation in B decay has been established and the measurement of sin(2beta) in
\psi K modes reached 5% accuracy. I discuss the implications of these, and of
the possible deviations of the CP asymmetries in b->s modes from that in \psi
K. The first meaningful measurements of alpha and gamma are explained, together
with their significance for constraining both the SM and new physics in B-Bbar
mixing. I also discuss implications of recent developments in the theory of
nonleptonic decays for B->pi K rates and CP asymmetries, and for the
polarization in charmless B decays to two vector mesons.Comment: Plenary talk at 32nd International Conference on High Energy Physics
(ICHEP'04), August 16-22, 2004, Beijing, China. v2: Table 5 corrected, minor
changes in some averages (updated to hfag, that include correlations between
S and C). v3: Figure 8 fixed, minor final change
New Physics Effects in Decays
We present a model-independent analysis of rare B decays, . The effect of possible new physics is written in terms of dimension-6
four-fermi interactions. The lepton number violating scalar- and tensor-type
interactions are included, and they induce decays. We show systematically how the branching ratios and
missing mass-squared spectrum depend on the coefficients of the four-fermi
interactions.Comment: 20 pages with 7 figure
mixing and transitions in isosinglet down quark model
The recent observation of the mass difference in system seems to be not
in complete agreement with the corresponding standard model value. We consider
the model with an extra vector like down quark to explain this discrepancy and
obtain the constraints on the new physics parameters. Thereafter, we show that
with these new constraints this model can successfully explain other observed
deviations associated with transitions, namely, ,
and .Comment: 19 pages, 6 figure
A Hybrid Model of Neutrino Masses and Oscillations: Bulk Neutrinos in the Split-Fermion Scenario
Higher-dimensional models of neutrino physics with one or more right-handed
neutrinos in the bulk have attracted considerable attention in recent years.
However, a critical issue for such models is to find a way of introducing the
required flavor dependence needed for generating neutrino oscillations. In this
paper, we point out that a natural ``minimal'' framework that accomplishes this
can be constructed by combining the bulk-neutrino hypothesis for right-handed
neutrinos with the split-fermion scenario for left-handed neutrinos. This
combination leads to a unique flavor signature for neutrino phenomenology which
easily incorporates large flavor mixing angles. This hybrid scenario also has a
number of additional important features. For example, one previous difficulty
of the split-fermion scenario applied to neutrinos has been that the mass
matrix is exponentially sensitive to neutrino displacements within the brane.
However, in our hybrid scenario, the interactions between the brane and bulk
naturally convert this dependence from exponential to linear. Another important
feature is that our hybrid scenario provides its own natural regulator for
Kaluza-Klein sums. Thus, in our scenario, all Kaluza-Klein summations are
manifestly finite, even in cases with multiple extra dimensions. But most
importantly, our mechanism completely decouples the effective neutrino flavor
mixing angles from the sizes of the overlaps between the neutrino wavefunctions
within the brane. Thus, we are able to obtain large neutrino mixing angles even
when these neutrinos have significant spatial separations and their overlaps
vanish.Comment: 11 pages, LaTeX, 1 figur
Implications of Charmless B Decays with Large Direct CP Violation
Based on the most recent data in charmless B decays including the very
recently reported large direct CP violations, it is shown that the weak phase
gamma can well be extracted without two-fold ambiguity even only from two decay
modes pi^+pi^- and pi^+K^-, and its value is remarkably consistent with the
global standard model fit at a compatible accuracy. A fit to all the pi pi, pi
K data favor both large electroweak penguin and color-suppressed tree amplitude
with large strong phases. It is demonstrated that the inclusion of small
SU(3)symmetry breaking effects of strong phases and the inelastic rescattering
effects can well improve the consistency of the data, while both effects may
not be sufficient to arrive at a small electroweak penguin amplitude in the
standard model. It is of interest to notice that large or small electroweak
penguin amplitude becomes a testable prediction as they lead to significantly
different predictions for the direct CP violations for pi^0 pi^0, pi^0 K^0
modes. Clearly, precise measurements on charmless B decays will provide a
window for probing new physics.Comment: 4 pages, 1 figure, 1 table, results updated with the latest data.
conclusions unchanged. Refence added. published versio
Phenomenological Consequences of Soft Leptogenesis
Soft supersymmetry breaking terms involving heavy singlet sneutrinos can be
the dominant source of leptogenesis. The relevant range of parameters is
different from standard leptogenesis: a lighter Majorana mass, M < 10^9 GeV
(allowing a solution of the gravitino problem), and smaller Yukawa couplings,
Y_N < 10^{-4}. We investigate whether the various couplings of the singlet
sneutrinos, which are constrained by the requirement of successful `soft
leptogenesis', can have observable phenomenological consequences. Specifically,
we calculate the contributions of the relevant soft supersymmetric breaking
terms to the electric dipole moments of the charged leptons and to lepton
flavor violating decays. Our result is that these contributions are small.Comment: 11 pages, 1 figure; v2: an additional contribution is considered
(modifying: fig. 1, eq. 10-13, 22) and a reference added. Conclusions
unchange
Constraining the CKM Parameters using CP Violation in semi-leptonic B Decays
We discuss the usefulness of the CP violating semi-leptonic asymmetry a_{SL}
not only as a signal of new physics, but also as a tool in constraining the CKM
parameters. We show that this technique could yield useful results in the first
years of running at the B factories. We present the analysis graphically in
terms of M_{12}, the dispersive part of the B-Bbar mixing amplitude. This is
complementary to the usual unitarity triangle representation and often allows a
cleaner interpretation of the data.Comment: 15 pages REVTEX, 7 figure
The B -> pi pi, pi K Puzzles: Implications for Hadron Physics, New Physics and Rare Decays
The B-meson system is an interesting probe for the exploration of strong
interactions, the quark-flavour sector of the Standard Model, and the search
for new physics. In this programme, non-leptonic B decays, which are
particularly challenging from the point of view of QCD, play a key role. After
discussing strategies to deal with the corresponding hadronic matrix elements
of four-quark operators and popular avenues for new physics to manifest itself
in B decays, we focus on puzzling patterns in the B-factory data for B -> pi
pi, pi K decays; we explore their implications for hadron physics, new physics
and rare K and B decays.Comment: 10 pages, 2 figures, plenary talk at the International Conference on
QCD and Hadronic Physics, Peking University, Beijing, China, 16-20 June 2005,
to appear in the Proceeding
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