137 research outputs found
Cosmology and CP Violation
We describe the role of CP violation in the generation of the baryon
asymmetry of the Universe, in the framework of baryogenesis through
leptogenesis, with emphasis on the possible relationship between CP violation
at low energies and that required by leptogenesis. It is emphasized that a
direct link between these two manifestations of CP violation only exists in the
framework of specific flavour structures for the fundamental leptonic mass
matrices.Comment: 11 pages, Invited Talk at Flavor Physics And CP Violation (FPCP 2003)
3-6 Jun 2003, Paris, Franc
CP Violation and New Physics
We describe some of the extensions of the SM, including models with
spontaneous CP violation, where New Physics relevant for CP violation may
arise. It is emphasized that the SM predicts a series of exact relations among
various measurable quantities, such as moduli of CKM matrix elements and
rephasing invariant phases. These exact relations provide a stringent test of
the SM, with the potential to reveal New Physics.Comment: Invited talk at Workshop on the CKM Unitarity Triangle, IPPP Durham,
April 2003. 8 pages, 1 figur
Vacuum Induced CP Violation Generating a Complex CKM Matrix with Controlled Scalar FCNC
We propose a viable minimal model with spontaneous CP violation in the
framework of a Two Higgs Doublet Model. The model is based on a generalised
Branco-Grimus-Lavoura model with a flavoured symmetry, under
which two of the quark families are even and the third one is odd. The
lagrangian respects CP invariance, but the vacuum has a CP violating phase,
which is able to generate a complex CKM matrix, with the rephasing invariant
strength of CP violation compatible with experiment. The question of scalar
mediated flavour changing neutral couplings is carefully studied. In particular
we point out a deep connection between the generation of a complex CKM matrix
from a vacuum phase and the appearance of scalar FCNC. The scalar sector is
presented in detail, showing that the new scalars are necessarily lighter than
1 TeV. A complete analysis of the model including the most relevant constraints
is performed, showing that it is viable and that it has definite implications
for the observation of New Physics signals in, for example, flavour changing
Higgs decays or the discovery of the new scalars at the LHC. We give special
emphasis to processes like , as well as , which are relevant for the LHC and the ILC.Comment: 36 pages, 11 figure
CP Violation and Flavour Mixings in Orbifold GUTs
We address the flavour problem by incorporating the hypothesis of universal
strength of Yukawa couplings in the framework of a 5D GUT model compactified on
an orbifold. We show that a quantitatively
successful picture of fermion masses and mixings emerges from the interplay
between the bulk suppression factors of geometric origin and the phases of the
Yukawa matrices. We give an explicit example, where we obtain a good fit for
both the CKM and PMNS matrices.Comment: 8 pages, no figures; v2: minor changes, published in Phys Rev D
(Rapid Communication
Invariant approach to CP in family symmetry models
We propose the use of basis invariants, valid for any choice of CP
transformation, as a powerful approach to studying specific models of CP
violation in the presence of discrete family symmetries. We illustrate the
virtues of this approach for examples based on and family
symmetries. For , we show how to elegantly obtain several known results in
the literature. In we use the invariant approach to identify how
explicit (rather than spontaneous) CP violation arises, which is geometrical in
nature, i.e. persisting for arbitrary couplings in the Lagrangian.Comment: 4 pages plus references. v2: to be published in PR
Invariant approach to CP in unbroken
The invariant approach is a powerful method for studying CP violation for
specific Lagrangians. The method is particularly useful for dealing with
discrete family symmetries. We focus on the CP properties of unbroken
invariant Lagrangians with Yukawa-like terms, which proves to be a
rich framework, with distinct aspects of CP, making it an ideal group to
investigate with the invariant approach. We classify Lagrangians depending on
the number of fields transforming as irreducible triplet representations of
. For each case, we construct CP-odd weak basis invariants and use
them to discuss the respective CP properties. We find that CP violation is
sensitive to the number and type of representations.Comment: 24 pages, 1 figure. v2: to be published in NP
Unitarity Relations in the Presence of Vector-Like Quarks
We study, in a systematic way, the unitarity relations which
arise in extensions of the three generations Standard Model (3gSM) involving
the addition of vector-like quarks (VLQ). In particular, we emphasize the
effect of the presence of VLQ on moduli differences, as well
on the size of the imaginary parts of rephasing invariant
quartets. We consider the special case where an up-type VLQ is used to attempt
at solving the unitarity problem in the first line of .Comment: 9 page
CP-odd invariants in models with several Higgs doublets
We present CP-odd Higgs-basis invariants, which can be used to signal CP
violation in a multi-Higgs system, written in an arbitrary Higgs basis. It is
shown through specific examples how these CP-odd invariants can also be useful
to determine the character of CP breaking (i.e. whether it is hard or soft CP
breaking) in a given Higgs Lagrangian. We analyse in detail the cases of two
and three Higgs doublets
Universal Doublet-Singlet Higgs Couplings and phenomenology at the CERN Large Hadron Collider
We consider a minimal extension of the standard model where a real, gauge
singlet scalar field is added to the standard spectrum. Introducing the Ansatz
of universality of scalar couplings, we are led to a scenario which has a set
of very distinctive and testable predictions: (i) the mixing between the
standard model Higgs and the new state is near maximal, (ii) the ratio of the
two Higgs mass eigenstates is fixed (), (iii) the decay modes of
each of the two eigenstates are standard model like. We also study how
electroweak precision tests constrain this scenario. We predict the lighter
Higgs to lie in the range of 114 and 145 GeV, and hence the heavier one between
198 and 250 GeV. The predictions of the model can be tested at the upcoming
LHC.Comment: 5 pages, no figures; v2: normalisations settled, results unchanged,
References added; v3: a new section 'Deviation from universality' added,
version to appear in Phys Rev D (Brief Reports section
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