42 research outputs found
Atmospheric Neutrinos Can Make Beauty Strange
The large observed mixing angle in atmospheric neutrinos, coupled with Grand
Unification, motivates the search for a large mixing between right-handed
strange and bottom squarks. Such mixing does not appear in the standard CKM
phenomenology, but may induce significant b to s transitions through gluino
diagrams. Working in the mass eigenbasis, we show quantitatively that an order
one effect on CP violation in B_d to phi+K_S is possible due to a large mixing
between right-handed b and s squarks, while still satisfying constraints from b
to s + gamma. We also include the effect of right- and left-handed bottom
squark mixing proportional to m_b*mu*tan(beta). For small mu*tan(beta) there
may also be a large effect in B_s mixing correlated with a large effect in B_d
to phi+K_S, typically mixing effects are greater than 100 ps^{-1}, an
unambiguous signal of new physics at Tevatron Run II.Comment: 32 pages, LaTeX. Corrected a factor of two mistake in the code; the
possible impact on B -> phi K_s became larger. Figures and discussion
updated, a reference adde
Flavour Violation in Anomaly Mediated Supersymmetry Breaking
We study squark flavour violation in the anomaly mediated supersymmetry
broken (AMSB) minimal supersymmetric standard model. Analytical expressions for
the three-generational squark mass matrices are derived. We show that the
anomaly-induced soft breaking terms have a decreasing amount of squark flavour
violation when running from the GUT to the weak scale. Taking into account
inter-generational squark mixing, we work out non-trivial constraints from B ->
Xs gamma and Bs -> mu mu, which complement each other, as well as B -> tau nu
decays. We further identify a region of parameter space where the anomalous
magnetic moment of the muon and the B -> Xs gamma branching ratio are
simultaneously accommodated. Since anomaly mediation is of the minimal
flavour-violating type, the generic flavour predictions for this class of
models apply, including a CKM-induced (and hence small) Bs-Bsbar-mixing phase.Comment: 32 pages, 8 figures. v2: minor clarifications, reference added, to
appear in JHE
Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments
We report a new measurement of the B-meson semileptonic decay momentum
spectrum that has been made with a sample of 9.4/fb of electron-positron
annihilation data collected with the CLEO II detector at the Y(4S) resonance.
Electrons from primary semileptonic decays and secondary charm decays were
separated by using charge and angular correlations in Y(4S) events with a
high-momentum lepton and an additional electron. We determined the semileptonic
branching fraction to be (10.91 +- 0.09 +- 0.24)% from the normalization of the
electron-energy spectrum. We also measured the moments of the electron energy
spectrum with minimum energies from 0.6 GeV to 1.5 GeV.Comment: 36 pages postscript, als available through
http://w4.lns.cornell.edu/public/CLNS/, Submitted to PRD (back-to-back with
preceding preprint hep-ex/0403052
Search for the lepton flavor violating decay A^0/H^0 --> tau^{+/-} mu^{+/-} at hadron colliders
In the two Higgs doublet model type III and in several other extensions of
the Standard Model, there are no discrete symmetries that suppress flavor
changing couplings at tree level. The experimental observation of the nu_mu --
nu_tau flavor oscillation may suggest the non-conservation of lepton number.
This would lead to the decay of the type A^0/H^0 --> tau^{+/-} mu^{+/-}. We
determine the present low energy limit on lepton flavor violating (LFV)
couplings from the muon g-2 measurement and discuss the prospects for detecting
lepton flavor violating decays at the TeVatron and at the Large Hadron
Collider. The achievable bounds on the LFV coupling parameter lambda_{tau mu}
are presented.Comment: 19 pages, 21 figures. Updated version takes into account the recent
results on the muon g-2 measurements. Submitted to Phys. Rev. D. Added minor
corrections from a refere
The Top Quark Decay Vertex in Standard Model Extensions
New physics interactions can affect the strength and structure of the
vertex. We investigate the magnitudes and phases of "anomalous" contributions
to this vertex in a two-Higgs doublet and the minimal supersymmetric extension
of the standard model, and in a top-color assisted technicolor (TC2) model.
While the magnitudes of the anomalous couplings remain below 1 percent in the
first two models, TC2 interactions can reduce the left-chiral coupling by
several percent.Comment: Latex, 27 pages, 14 figure
Functional mechanisms underlying pleiotropic risk alleles at the 19p13.1 breast-ovarian cancer susceptibility locus
A locus at 19p13 is associated with breast cancer (BC) and ovarian cancer (OC) risk. Here we analyse 438 SNPs in this region in 46,451 BC and 15,438 OC cases, 15,252 BRCA1 mutation carriers and 73,444 controls and identify 13 candidate causal SNPs associated with serous OC (P=9.2 × 10-20), ER-negative BC (P=1.1 × 10-13), BRCA1-associated BC (P=7.7 × 10-16) and triple negative BC (P-diff=2 × 10-5). Genotype-gene expression associations are identified for candidate target genes ANKLE1 (P=2 × 10-3) and ABHD8 (P<2 × 10-3). Chromosome conformation capture identifies interactions between four candidate SNPs and ABHD8, and luciferase assays indicate six risk alleles increased transactivation of the ADHD8 promoter. Targeted deletion of a region containing risk SNP rs56069439 in a putative enhancer induces ANKLE1 downregulation; and mRNA stability assays indicate functional effects for an ANKLE1 3′-UTR SNP. Altogether, these data suggest that multiple SNPs at 19p13 regulate ABHD8 and perhaps ANKLE1 expression, and indicate common mechanisms underlying breast and ovarian cancer risk
Collider aspects of flavour physics at high Q
This review presents flavour related issues in the production and decays of
heavy states at LHC, both from the experimental side and from the theoretical
side. We review top quark physics and discuss flavour aspects of several
extensions of the Standard Model, such as supersymmetry, little Higgs model or
models with extra dimensions. This includes discovery aspects as well as
measurement of several properties of these heavy states. We also present public
available computational tools related to this topic.Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era
of the LHC'', Geneva, Switzerland, November 2005 -- March 200