1,768 research outputs found
Implications of large dimuon CP asymmetry in B_{d,s} decays on minimal flavor violation with low tan beta
The D0 collaboration has recently announced evidence for a dimuon CP
asymmetry in B_{d,s} decays of order one percent. If confirmed, this asymmetry
requires new physics. We argue that for minimally flavor violating (MFV) new
physics, and at low tan beta=v_u/v_d, there are only two four-quark operators
(Q_{2,3}) that can provide the required CP violating effect. The scale of such
new physics must lie below 260 GeV sqrt{tan beta}. The effect is universal in
the B_s and B_d systems, leading to S_{psi K}~sin(2beta)-0.15 and S_{psi
phi}~0.25. The effects on epsilon_K and on electric dipole moments are
negligible. The most plausible mechanism is tree-level scalar exchange. MFV
supersymmetry with low tan beta will be excluded. Finally, we explain how a
pattern of deviations from the Standard Model predictions for S_{psi phi},
S_{psi K} and epsilon_K can be used to test MFV and, if MFV holds, to probe its
structure in detail.Comment: 11 pages. v2: References adde
On theories of enhanced CP violation in B_s,d meson mixing
The DO collaboration has measured a deviation from the standard model (SM)
prediction in the like sign dimuon asymmetry in semileptonic b decay with a
significance of 3.2 sigma. We discuss how minimal flavour violating (MFV)
models with multiple scalar representations can lead to this deviation through
tree level exchanges of new MFV scalars. We review how the two scalar doublet
model can accommodate this result and discuss some of its phenomenology. Limits
on electric dipole moments suggest that in this model the coupling of the
charged scalar to the right handed u-type quarks is suppressed while its
coupling to the d-type right handed quarks must be enhanced. We construct an
extension of the MFV two scalar doublet model where this occurs naturally.Comment: 10 pages, 7 figures, v3 final JHEP versio
CP Violation in Supersymmetry with Effective Minimal Flavour Violation
We analyze CP violation in supersymmetry with Effective Minimal Flavour
Violation, as recently proposed in arXiv:1011.0730. Unlike the case of standard
Minimal Flavour Violation, we show that all the phases allowed by the flavour
symmetry can be sizable without violating existing Electric Dipole Moment
constraints, thus solving the SUSY CP problem. The EDMs at one and two loops
are precisely analyzed as well as their correlations with the expected CP
asymmetries in B physics.Comment: 22 pages, 7 figures. v2: Discussion in section 2 extended,
conclusions unchanged. Matches published versio
Covariant Description of Flavor Conversion in the LHC Era
A simple covariant formalism to describe flavor and CP violation in the
left-handed quark sector in a model independent way is provided. The
introduction of a covariant basis, which makes the standard model approximate
symmetry structure manifest, leads to a physical and transparent picture of
flavor conversion processes. Our method is particularly useful to derive robust
bounds on models with arbitrary mechanisms of alignment. Known constraints on
flavor violation in the K and D systems are reproduced in a straightforward
manner. Assumptions-free limits, based on top flavor violation at the LHC, are
then obtained. In the absence of signal, with 100 fb^{-1} of data, the LHC will
exclude weakly coupled (strongly coupled) new physics up to a scale of 0.6 TeV
(7.6 TeV), while at present no general constraint can be set related to Delta
t=1 processes. LHC data will constrain Delta F=2 contributions via same-sign
tops signal, with a model independent exclusion region of 0.08 TeV (1.0 TeV).
However, in this case, stronger bounds are found from the study of CP violation
in D-bar D mixing with a scale of 0.57 TeV (7.2 TeV). In addition, we apply our
analysis to models of supersymmetry and warped extra dimension. The minimal
flavor violation framework is also discussed, where the formalism allows to
distinguish between the linear and generic non-linear limits within this class
of models.Comment: 24 pages, 6 figures. Some corrections and clarifications; references
added. Matches published versio
Beautiful Mirrors at the LHC
We explore the "Beautiful Mirrors" model, which aims to explain the measured
value of , discrepant at the level. This scenario
introduces vector-like quarks which mix with the bottom, subtly affecting its
coupling to the . The spectrum of the new particles consists of two
bottom-like quarks and a charge -4/3 quark, all of which have electroweak
interactions with the third generation. We explore the phenomenology and
discovery reach for these new particles at the LHC, exploring single mirror
quark production modes whose rates are proportional to the same mixing
parameters which resolve the anomaly. We find that for mirror quark
masses is required to
reasonably establish the scenario and extract the relevant mixing parameters.Comment: version to be published in JHE
Higgs-mediated FCNCs: Natural Flavour Conservation vs. Minimal Flavour Violation
We compare the effectiveness of two hypotheses, Natural Flavour Conservation
(NFC) and Minimal Flavour Violation (MFV), in suppressing the strength of
flavour-changing neutral-currents (FCNCs) in models with more than one Higgs
doublet. We show that the MFV hypothesis, in its general formulation, is more
stable in suppressing FCNCs than the hypothesis of NFC alone when quantum
corrections are taken into account. The phenomenological implications of the
two scenarios are discussed analysing meson-antimeson mixing observables and
the rare decays B -> mu+ mu-. We demonstrate that, introducing flavour-blind CP
phases, two-Higgs doublet models respecting the MFV hypothesis can accommodate
a large CP-violating phase in Bs mixing, as hinted by CDF and D0 data and,
without extra free parameters, soften significantly in a correlated manner the
observed anomaly in the relation between epsilon_K and S_psi_K.Comment: 27 pages, 4 figures. v3: minor modifications (typos corrected and few
refs. added), conclusions unchanged; journal versio
Theory of Multidimensional Solitons
We review a number of topics germane to higher-dimensional solitons in
Bose-Einstein condensates. For dark solitons, we discuss dark band and planar
solitons; ring dark solitons and spherical shell solitons; solitary waves in
restricted geometries; vortex rings and rarefaction pulses; and multi-component
Bose-Einstein condensates. For bright solitons, we discuss instability,
stability, and metastability; bright soliton engineering, including pulsed atom
lasers; solitons in a thermal bath; soliton-soliton interactions; and bright
ring solitons and quantum vortices. A thorough reference list is included.Comment: review paper, to appear as Chapter 5a in "Emergent Nonlinear
Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P.
G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez
(Springer-Verlag
Dark Matter from Minimal Flavor Violation
We consider theories of flavored dark matter, in which the dark matter
particle is part of a multiplet transforming nontrivially under the flavor
group of the Standard Model in a manner consistent with the principle of
Minimal Flavor Violation (MFV). MFV automatically leads to the stability of the
lightest state for a large number of flavor multiplets. If neutral, this
particle is an excellent dark matter candidate. Furthermore, MFV implies
specific patterns of mass splittings among the flavors of dark matter and
governs the structure of the couplings between dark matter and ordinary
particles, leading to a rich and predictive cosmology and phenomenology. We
present an illustrative phenomenological study of an effective theory of a
flavor SU(3)_Q triplet, gauge singlet scalar.Comment: 10 pages, 2 figures; v2: references added, minor changes to collider
analysis, conclusions unchange
MFV Reductions of MSSM Parameter Space
The 100+ free parameters of the minimal supersymmetric standard model (MSSM)
make it computationally difficult to compare systematically with data,
motivating the study of specific parameter reductions such as the cMSSM and
pMSSM. Here we instead study the reductions of parameter space implied by using
minimal flavour violation (MFV) to organise the R-parity conserving MSSM, with
a view towards systematically building in constraints on flavour-violating
physics. Within this framework the space of parameters is reduced by expanding
soft supersymmetry-breaking terms in powers of the Cabibbo angle, leading to a
24-, 30- or 42-parameter framework (which we call MSSM-24, MSSM-30, and MSSM-42
respectively), depending on the order kept in the expansion. We provide a
Bayesian global fit to data of the MSSM-30 parameter set to show that this is
manageable with current tools. We compare the MFV reductions to the
19-parameter pMSSM choice and show that the pMSSM is not contained as a subset.
The MSSM-30 analysis favours a relatively lighter TeV-scale pseudoscalar Higgs
boson and with multi-TeV sparticles.Comment: 2nd version, minor comments and references added, accepted for
publication in JHE
Charged-Higgs phenomenology in the Aligned two-Higgs-doublet model
The alignment in flavour space of the Yukawa matrices of a general
two-Higgs-doublet model results in the absence of tree-level flavour-changing
neutral currents. In addition to the usual fermion masses and mixings, the
aligned Yukawa structure only contains three complex parameters, which are
potential new sources of CP violation. For particular values of these three
parameters all known specific implementations of the model based on discrete
Z_2 symmetries are recovered. One of the most distinctive features of the
two-Higgs-doublet model is the presence of a charged scalar. In this work, we
discuss its main phenomenological consequences in flavour-changing processes at
low energies and derive the corresponding constraints on the parameters of the
aligned two-Higgs-doublet model.Comment: 46 pages, 19 figures. Version accepted for publication in JHEP.
References added. Discussion slightly extended. Conclusions unchange
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