6 research outputs found
Kaon mixing and the charm mass
We study contributions to the Delta S=2 weak Chiral Lagrangian producing
K0-K0bar mixing which are not enhanced by the charm mass. For the real part,
these contributions turn out to be related to the box diagram with up quarks
but, unlike in perturbation theory, they do not vanish in the limit m_u->0.
They increase the leading contribution to the K_L-K_S mass difference by ~10%.
This means that short distances amount to (90+-15)% of this mass difference.
For the imaginary part, we find a correction to the lambda_c^2 m_c^2 term of
-5% from the integration of charm, which is a small contribution to epsilon_K.
The calculation is done in the large-Nc limit and we show explicitly how to
match short and long distances.Comment: 20 pages, 5 figures. Typos fixe
Footprints of the Beyond in flavor physics: Possible role of the Top Two Higgs Doublet Model
The B-factories results provide an impressive confirmation of the Standard
Model (SM) description of flavor and CP violation. Nevertheless, as more data
were accumulated, deviations in the 2.5-3.5 sigma range have emerged pointing
to the exciting possibility of new CP-odd phase(s) and flavor violating
parameters in B-decays. Primarily this seems to be the case in the time
dependent CP asymmetries in penguin dominated modes (e.g. B -> phi (eta') Ks).
We discuss these and other deviations from the SM and, as an illustration of
possible new physics scenarios, we examine the role of the Top Two Higgs
Doublet Model. This is a simple extension of the SM obtained by adding second
Higgs doublet in which the Yukawa interactions of the two Higgs doublets are
assigned in order to naturally account for the large top-quark mass.
Of course, many other extensions of the Standard Model could also account for
these experimental deviations. Clearly if one takes these deviations seriously
then some new particles in the 300 GeV to few TeV with associated new CP-odd
phase(s) are needed.Comment: 40 pages, 17 figures (png format), uses pdflate
Obtaining CKM Phase Information from B Penguin Decays
We discuss a method for extracting CP phases from pairs of B decays which are
related by flavor SU(3). One decay (B0 -> M1 M2) receives a significant bbar ->
dbar penguin contribution. The second (B' -> M1' M2') has a significant bbar ->
sbar penguin contribution, but is dominated by a single amplitude. CP phase
information is obtained using the fact that the B' -> M1' M2' amplitude is
related by SU(3) to a piece of the B0 -> M1 M2 amplitude. The leading-order
SU(3)-breaking effect (~25%) responsible for the main theoretical error can be
removed. For some decay pairs, it can be written in terms of known decay
constants. In other cases, it involves a ratio of form factors. However, this
form-factor ratio can either be measured experimentally, or eliminated by
considering a double ratio of amplitudes. In all cases, one is left only with a
second-order effect, ~5%. We find twelve pairs of B decays to which this method
can be applied. Depending on the decay pair, we estimate the total theoretical
error in relating the B' -> M1' M2' and B0 -> M1 M2 amplitudes to be between 5%
and 15%. The most promising decay pairs are Bd -> pi+ pi- and Bu+ -> K0 pi+,
and Bd -> D+ D- and Bd -> Ds+ D- or Bu+ -> Ds+ D0bar.Comment: 38 pages, JHEP format, no figures. Comments added to text regarding
most promising decay pairs; references added; conclusions unchange
Minimal Flavour Violation Waiting for Precise Measurements of Delta M_s, S_{psi phi}, A^s_SL, |V_ub|, gamma and B^0_{s,d} -> mu+ mu-
We emphasize that the recent measurements of the B^0_s - bar B^0_s mass
difference Delta M_s by the CDF and D0 collaborations offer an important model
independent test of minimal flavour violation (MFV). The improved measurements
of the angle gamma in the unitarity triangle and of |V_ub| from tree level
decays, combined with future accurate measurements of Delta M_s, S_{psi K_S},
S_{psi phi}, Br(B_{d,s} -> mu+ mu-), Br(B -> X_{d,s} nu bar nu), Br(K+ -> pi+
nu bar nu) and Br(K_L -> pi^0 nu bar nu) and improved values of the relevant
non-perturbative parameters, will allow to test the MFV hypothesis in a model
independent manner to a high accuracy. In particular, the difference between
the reference unitarity triangle obtained from tree level processes and the
universal unitarity triangle (UUT) in MFV models would signal either new
flavour violating interactions and/or new local operators that are suppressed
in MFV models with low tan(beta), with the former best tested through S_{psi
phi} and K_L -> pi^0 nu bar nu. A brief discussion of non-MFV scenarios is also
given. In this context we identify in the recent literature a relative sign
error between Standard Model and new physics contributions to S_{psi phi}, that
has an impact on the correlation between S_{psi phi} and A^s_SL. We point out
that the ratios S_{psi phi}/A^s_SL and (Delta M_s)/(Delta Gamma_s) will allow
to determine (Delta M_s)/(Delta M_s)^SM. Similar proposals for the
determination of (Delta M_d)/(Delta M_d)^SM are also given.Comment: 22 pages, 8 figures, 1 table. Extended discussion of the correlation
between S_{psi phi} and A^s_SL and new proposals to determine Delta
M_q/(Delta M_q)^SM from future measurements, with respect to the first
version. Minor changes and few references adde
Weak decays of : the non-leptonic case
In our previous study, we calculated the transition from factors of
using the QCD sum rules. Based on the factorization
approximation, the obtained form factors can be applied to evaluate the weak
non-leptonic decay rates of , where stands for a
light pseudoscalar or vector meson. We predict that the branching ratio for
inclusive non-leptonic two-body weak decays of which are realized via
the spectator mechanism, can be as large as , in
particular, the branching ratio of can reach
. Such values will be marginally accessed by the ability of
BESIII which will begin running very soon.Comment: 16 pages, revTex4, 1 figur
Towards the european strategy for particle physics: The briefing book
This document was prepared as part of the briefing material for the Workshop
of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May
2006. It gives an overview of the physics issues and of the technological
challenges that will shape the future of the field, and incorporates material
presented and discussed during the Symposium on the European Strategy for
Particle Physics, held in Orsay from 30th January to 2nd February 2006,
reflecting the various opinions of the European community as recorded in
written submissions to the Strategy Group and in the discussions at the
Symposium