25,032 research outputs found
CP Violation in B and K Decays: 2003
These lectures give a brief description of CP violation in B and K meson
decays with particular emphasize put on the determination of the CKM matrix.
The following topics will be discussed: i) The CKM matrix, the unitarity
triangle and general aspects of the theoretical framework, ii)
Particle-antiparticle mixing and various types of CP violation, iii) Standard
analysis of the unitarity triangle, iv) The ratio epsilon^prime/epsilon, v) The
most important strategies for the determination of the angles ,
and from B decays, vi) Rare decays and
vii) Models with minimal flavour violation.Comment: Schladming lectures 2003, Main latex-file, 8 figures, 51 page
Sweeping the Space of Admissible Quark Mass Matrices
We propose a new and efficient method of reconstructing quark mass matrices
from their eigenvalues and a complete set of mixing observables. By a
combination of the principle of NNI (nearest neighbour interaction) bases which
are known to cover the general case, and of the polar decomposition theorem
that allows to convert arbitrary nonsingular matrices to triangular form, we
achieve a parameterization where the remaining freedom is reduced to one
complex parameter. While this parameter runs through the domain bounded by a
circle with radius R determined by the up-quark masses around the origin in the
complex plane one sweeps the space of all mass matrices compatible with the
given set of data.Comment: 18 page
Anatomy of Prominent B and K Decays and Signatures of CP-Violating New Physics in the Electroweak Penguin Sector
The recent observation of B_d -> pi^0 pi^0 at the B factories with a
surprisingly large branching ratio represents a challenge for theory, and
complements the amazingly small B_d -> pi^+ pi^- rate. We point out that all
puzzling B -> pi pi features can be accommodated in the Standard Model (SM)
through non-factorizable hadronic interference effects, extract the relevant
parameters, and predict the CP asymmetries of B_d -> pi^0 pi^0. Using then
SU(3) flavour-symmetry and plausible dynamical assumptions, we fix the hadronic
B -> pi K parameters through their B -> pi pi counterparts, and determine the
CKM angle gamma, with a result in remarkable accordance with the usual fits for
the unitarity triangle. We may then analyse the B -> pi K system in the SM,
where we find agreement with the experimental picture, with the exception of
those observables that are significantly affected by electroweak (EW) penguins,
thereby suggesting new physics (NP) in this sector. Indeed, a moderate
enhancement of these topologies and a large CP-violating NP phase allow us to
describe any currently observed feature of the B -> pi K modes, and to predict
the CP-violating B_d -> pi^0 K_S observables. If we then restrict ourselves to
a specific scenario where NP enters only through Z^0 penguins, we obtain a link
to rare K and B decays, where the most spectacular NP effects are an
enhancement of the K_L -> pi^0 nu nu_bar rate by one order of magnitude with
BR(K_L -> pi^0 nu nu_bar) ~ 4 BR(K^+ -> pi^+ nu nu_bar), BR(K_L -> pi^0 e^+
e^-) = O(10^-10), (sin 2beta)_{pi nu nu_bar} < 0, and a large forward-backward
CP asymmetry in B_d -> K^* mu^+ mu^-. We address also epsilon'/epsilon and
other prominent decays, including B -> phi K and B -> J/psi K modes.Comment: 78 pages, 12 figures, LaTe
Renormalization of the neutrino mass matrix
The renormalization group equations for the general 2 by 2, complex, neutrino
mass matrix are shown to have exact, analytic solutions. Simple formulas are
given for the physical mixing angle, complex phase and mass ratio in terms of
their initial values and the energy scales. We also establish a (complex)
renormalization invariant relating these parameters. The qualitative features
of the physical parameters' renormalization are clearly illustrated in vector
field plots. In both the SM and MSSM, maximal mixing is a saddle point.Comment: 16 pages, 5 figure
Testing the Higgs Sector of the Minimal Supersymmetric Standard Model at Large Hadron Colliders
We study the Higgs sector of the Minimal Supersymmetric Standard Model, in
the context of proton-proton collisions at LHC and SSC energies. We assume a
relatively heavy supersymmetric particle spectrum, and include recent results
on one-loop radiative corrections to Higgs-boson masses and couplings. We begin
by discussing present and future constraints from the LEP experiments. We then
compute branching ratios and total widths for the neutral () and charged
() Higgs particles. We present total cross-sections and event rates for
the important discovery channels at the LHC and SSC. Promising physics
signatures are given by , or or , , and followed by
, which should allow for an almost complete coverage
of the parameter space of the model.Comment: 51 pages, 30 figures (not enclosed and not available via e-mail
Waiting for Precise Measurements of K^+->pi^+ nu nu and K_L->pi^0 nu nu
In view of future plans for accurate measurements of the theoretically clean
branching ratios Br(K+ -> pi+ nu nu) and Br(KL -> pi0 nu nu), that should take
place in the next decade, we collect the relevant formulae for quantities of
interest and analyze their theoretical and parametric uncertainties. We point
out that in addition to the angle beta in the unitarity triangle (UT) also the
angle gamma can in principle be determined from these decays with respectable
precision and emphasize in this context the importance of the recent NNLO QCD
calculation of the charm contribution to K+ -> pi+ nu nu and of the improved
estimate of the long distance contribution by means of chiral perturbation
theory. In addition to known expressions we present several new ones that
should allow transparent tests of the Standard Model (SM) and of its
extensions. While our presentation is centered around the SM, we also discuss
models with minimal flavour violation and scenarios with new complex phases in
decay amplitudes and meson mixing. We give a brief review of existing results
within specific extensions of the SM, in particular the Littlest Higgs Model
with T-parity, Z' models, the MSSM and a model with one universal extra
dimension. We derive a new "golden" relation between B and K systems that
involves (beta,gamma) and Br(KL -> pi0 nu nu) and investigate the virtues of
(R_t,beta), (R_b,gamma), (beta,gamma) and (etabar,gamma) strategies for the UT
in the context of K -> pi nu nu decays with the goal of testing the SM and its
extensions.Comment: 56 pages, 18 figures, Section on Long Distance Contributions, 2
Figures and few References added, Uses Rev Mod Phys Style; Includes new
results of NNLO calculation as well as matrix elements, extended and modified
sections on new physic
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