952 research outputs found

### Hunting the CKM weak phase with time-integrated Dalitz analyses of Bs -> K pi pi decays

We present a new technique to extract information on the Unitarity Triangle
from the study of Bs -> K pi pi Dalitz plot. Using isospin symmetry and the
possibility to access the decay amplitudes from Dalitz analyses, we propose a
new strategy to extract the weak phase gamma from Bs to K pi pi.Comment: 2 pages. v2: Discussion of interference on Dalitz plot clarified. Bs
-> K K pi channels removed. v3: Improved discussion of experimental aspects.
Final version to appear in Phys. Lett.

### CP violation in supersymmetric theories

We review the present status of CP violating problem in supersymmetric
extensions of the standard model. We analyze the constraints imposed by the
experimental limits of the electron, neutron, and mercury electric dipole
moments on the supersymmetric CP phases and show that only the scenarios with
flavour-off- diagonal CP violation remain attractive. These scenarios require
hermitian Yukawa matrices which naturally arise in models with left-right
symmetry or a SU(3) flavour symmetry. In this case, epsilon_K and
epsilon'/epsilon can be saturated by a small non-universality of the soft
scalar masses through the gluino and chargino contributions respectively. The
model also predicts a strong correlation between A_{CP}(b-> s gamma) and the
neutron electric dipole moment. In this framework, the standard model gives a
the leading contribution to the CP asymmetry in B ->psi K_S decay, while the
dominant chargino contribution to this asymmetry is < 0.2. Thus, no constraint
is set on the non-universality of this model by the recent BaBar and Belle
measureets.Comment: 34 pages, 10 figures. Invited review article for International
Journal of Modern Physics

### Status of the CKM matrix

An updated determination of the parameters of the Cabibbo-Kobayashi-Maskawa
matrix is presented.Comment: 8 pages, 9 figures, uses espcrc2.sty. Talk given at the "7th Topical
Seminar on the Legacy of LEP and SLC", 8-11 October 2001, Siena (Italy

### 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

### B_s to K^(*)0 \bar K^(*)0 decays: the golden channels for new physics searches

We point out that time-dependent CP asymmetries in B_s to K^{*0} \bar K^{*0}
decays probe the presence of new physics in b to s transitions with an
unprecedented theoretical accuracy. We show that, contrary to the case of B_d
to phi K_S, it is possible to obtain a model-independent prediction for the
coefficient S(B_s to K^{*0} \bar K^{*0}) in the Standard Model. We give an
estimate of the experimental precision achievable with the next generation of B
physics experiments. We also discuss how this approach can be extended to the
case of B_s to \bar K^{*0} K^0, B_s to K^{*0} \bar K^0 and B_s to K^0 \bar K^0
decays and the different experimental challenges for these channels.Comment: 4 pages, 1 figure. v2: Corrected dependence on CKM angles, expanded
discussion of multiple polarizations, conclusions strengthened. Final version
to appear in PR

### The Chromomagnetic Dipole Operator and the B Semileptonic Branching Ratio

We consider the possibility of having a large branching ratio for the decay
$b\to s g$ coming from an enhanced Wilson coefficient of the chromomagnetic
dipole operator. We show that values of $BR(b\to s g)$ up to $\sim 10\%$ or
more are compatible with the constraints coming from the CLEO experimental
results on $BR(B\to X_s\gamma)$ and $BR(B\to X_s\phi)$. Such large values can
reconcile the predictions of both the semileptonic branching ratio and the
charm counting with the present experimental results. We also discuss a
supersymmetric model with gluino-mediated flavour violations, which can account
for such large values of $BR(b\to s g)$.Comment: 19 pages, 3 eps figures included, replacement with minor change

### Charming Penguins in B decays

Full expressions of the $B^0_d \to \pi^+ \pi^-$ and $B^0_d \to \pi^0 \pi^0$
amplitudes, given in terms of matrix elements of operators of the effective
weak Hamiltonian, are used to study the dependence of the relevant branching
ratios on the different contributions. The uncertainty in the extraction of the
weak phase $\alpha$ from the measurement of the time-dependent asymmetry in
$B^0_d \to \pi^+ \pi^-$ decays is also analyzed. We find that, among several
effects which may enhance the $B^0_d \to \pi^0 \pi^0$ branching ratio, the most
important is due to ``charming penguin" diagrams that have never been studied
before. These diagrams easily increase $BR(B^0_d \to \pi^0 \pi^0)$ up to a
value of $1-3 \times 10^{-6}$. The same effect produces, however, a large error
in the extraction of $\alpha$ from the measurement of the $B^0_d \to \pi^+
\pi^-$ time-dependent asymmetry. We show that it is possible to determine
charming-penguin amplitudes from the experimental measurement of many decay
rates. Their effect is impressive in $B^+ \to \pi^+ K^0$ and $B^0_d \to K^+
\pi^-$ decays, where charming-penguin contributions easily give values of
$BR(B^+ \to \pi^+ K^0)$ and $BR(B^0_d \to K^+ \pi^-)$ of about $1 \times
10^{-5}$. Among other possibilities, we also suggest to use $B^0_d \to K^0 \bar
K^0$, the BR of which can be as large as $2-3 \times 10^{-6}$, to determine the
size of charming-penguin amplitudes.Comment: LaTeX, 28 pages, 8 figure

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