2,182 research outputs found
The B -> pi K Puzzle and its Relation to Rare B and K Decays
The Standard-Model interpretation of the ratios of charged and neutral B-> pi
K rates, R_c and R_n, respectively, points towards a puzzling picture. Since
these observables are affected significantly by colour-allowed electroweak (EW)
penguins, this ``B -> pi K puzzle'' could be a manifestation of new physics in
the EW penguin sector. Performing the analysis in the R_n-R_c plane, which is
very suitable for monitoring various effects, we demonstrate that we may, in
fact, move straightforwardly to the experimental region in this plane through
an enhancement of the relevant EW penguin parameter q. We derive analytical
bounds for q in terms of a quantity L, that measures the violation of the
Lipkin sum rule, and point out that strong phases around 90 deg are favoured by
the data, in contrast to QCD factorisation. The B -> pi K modes imply a
correlation between q and the angle gamma that in the limit of negligible
rescattering effects and colour suppressed EW penguins depends only on the
value of L. Concentrating on a minimal flavour-violating new-physics scenario
with enhanced Z^0 penguins, we find that the current experimental values on
B -> X_s mu^+ mu^- require roughly L pi K data give L =
5.7 +- 2.4, L has either to move to smaller values once the B -> pi K data
improve or new sources of flavour and CP violation are needed. In turn, the
enhanced values of L seen in the B -> pi K data could be accompanied by
enhanced branching ratios for rare decays. Most interesting turns out to be the
correlation between the B -> pi K modes and BR(K^+ -> pi^+ nu nu), with the
latter depending approximately on a single ``scaling'' variable \bar L= L
(|V_{ub}/V_{cb}|/0.086)^2.3.Comment: 19 pages, 7 figures, a few typos corrected and two references adde
Flavour Visions
This decade will allow to improve the resolution of the short distance scales
by at least an order of magnitude, extending the picture of fundamental physics
down to scales m with the help of the LHC. Further resolution
down to scales as short as m should be possible with the help of high
precision experiments in which flavour violating processes will play a
prominent role. Will this increase in resolution allow us to see new particles
(new animalcula) similarly to what Antoni van Leeuvenhoek saw by discovering
bacteria in 1676? The basic question for particle physics is how these new
animalcula will look like and which difficulties of the Standard Model (SM)
they will help us to solve and which new puzzles and problems they will bring
with them. I will describe what role flavour physics will play in these
exciting times provided this new world is animalculated.Comment: 18 pages, 1 Figure, Talk given at the 13th International Conference
on B-Physics at Hadron Machines, April 4-8 2011 Amsterdam, the Netherland
Two--Loop Anomalous Dimension Matrix for Weak Non-Leptonic Decays II:
We calculate the two--loop anomalous dimension matrix to order
\ord(\alpha_e \alpha_s) in the dimensional regularization scheme with
anticommuting (NDR) which is necessary for the extension of the
weak Hamiltonian involving electroweak penguins beyond the leading
logarithmic approximation. We demonstrate, how a direct calculation of penguin
diagrams involving in closed fermion loops can be avoided thus
allowing a consistent calculation of two--loop anomalous dimensions in the
simplest renormalization scheme with anticommuting in
dimensions. We give the necessary one--loop finite terms which allow to obtain
the corresponding two--loop anomalous dimension matrix in the HV scheme with
non--anticommuting .Comment: 25 page
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
Flavour Theory and the LHC Era
This decade should make a significant progress towards the Theory of Flavour
and the main goal of this talk is to transfer this believe to my colleagues in
the particle physics community. Indeed a significant part of this decade could
turn out to be the Flavour Era with participation of the LHC, Belle II,
Super-Flavour-Facility and dedicated Kaon and lepton flavour violation
experiments. Selected superstars of flavour physics listed below will play a
prominent role in these events. In this writeup the leading role is played by
the prima donna of 2010: CP violation in B_s system.Comment: 17 Pages, 1 Figure, Plenary talk presented at the Symposium "Physics
at the LHC 2010", DESY, June, 201
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