3,057 research outputs found
CP violation conditions in N-Higgs-doublet potentials
Conditions for CP violation in the scalar potential sector of general
N-Higgs-doublet models (NHDMs) are analyzed from a group theoretical
perspective. For the simplest two-Higgs-doublet model (2HDM) potential, a
minimum set of conditions for explicit and spontaneous CP violation is
presented. The conditions can be given a clear geometrical interpretation in
terms of quantities in the adjoint representation of the basis transformation
group for the two doublets. Such conditions depend on CP-odd pseudoscalar
invariants. When the potential is CP invariant, the explicit procedure to reach
the real CP-basis and the explicit CP transformation can also be obtained. The
procedure to find the real basis and the conditions for CP violation are then
extended to general NHDM potentials. The analysis becomes more involved and
only a formal procedure to reach the real basis is found. Necessary conditions
for CP invariance can still be formulated in terms of group invariants: the
CP-odd generalized pseudoscalars. The problem can be completely solved for
three Higgs-doublets.Comment: RevTeX4 used. Minor modifications, in particular, the parameter
counting of . v3: Eqs.(28)-(31) correcte
A numerical study of the effect of single overloads on plasticity induced crack closure
In this work, the effect of single overloads on plasticity induced crack closure is studied. An elastic-plastic
finite element model was developed and the crack opening level was calculated from the contact forces
along the crack flank. The effects of the loading parameters and stress state are analysed, and the mechanisms
behind crack closure variations are identified. An overload is a traumatic event that eliminates
material’s memory relative to the load history. Crack tip blunting is the mechanism behind this memory
loss, since it eliminates crack closure. Material hardening has a major relevance on the evolution of plastic
blunting, which was evident in the variation of the CTOD parameter. On the other hand, the overload
produces strong plastic deformation ahead of the crack tip, giving rise to conditions for the rapid generation
of crack closure higher than before the event. The peak of crack closure was found to increase linearly
with the load increase above the maximum baseline value. The crack is totally closed for overload
ratios of about 2.5. Empirical models were developed for the peak of crack closure, for the delay of this
peak and for the stabilization distance after the overload. Finally, the stress state was found to have a
major effect on crack closure level after an overload.info:eu-repo/semantics/publishedVersio
High overtones of Dirac perturbations of a Schwarzschild black hole
Using the Frobenius method, we find high overtones of the Dirac quasinormal
spectrum for the Schwarzschild black hole. At high overtones, the spacing for
imaginary part of is equidistant and equals to
, ( is the black hole mass), which
is twice less than that for fields of integer spin. At high overtones, the real
part of goes to zero. This supports the suggestion that the
expected correspondence between quasinormal modes and Barbero-Immirzi parameter
in Loop Quantum Gravity is just a numerical coincidence.Comment: 5 pages, Latex, 3 figures, Physical Review D.,at pres
Large Neutrino Mixing with Universal Strength of Yukawa Couplings
We analyse, within the framework of universal strength for Yukawa couplings
(USY), various structures for the Dirac and Majorana neutrino mass matrices
giving rise, through the see-saw mechanism, to a degenerate mass spectrum. A
specific USY ansatz is presented for the charged lepton and neutrino effective
mass matrix, leading to quasi-degenerate neutrinos and a leptonic mixing matrix
which provides a large angle solution for both the atmospheric and solar
neutrino problems.Comment: 7 pages, ReVTeX, small comments adde
Hierarchy plus anarchy in quark masses and mixings
We introduce a new parameterisation of the effect of unknown corrections from
new physics on quark and lepton mass matrices. This parameterisation is used in
order to study how the hierarchies of quark masses and mixing angles are
modified by random perturbations of the Yukawa matrices. We discuss several
examples of flavour relations predicted by different textures, analysing how
these relations are influenced by the random perturbations. We also comment on
the unlikely possibility that unknown corrections contribute significantly to
the hierarchy of masses and mixings.Comment: LaTeX, 18 pages, 16 PS figure
New Physics and CP Violation in Singly Cabibbo Suppressed D Decays
We analyze various theoretical aspects of CP violation in singly Cabibbo
suppressed (SCS) D-meson decays, such as . In particular, we
explore the possibility that CP asymmetries will be measured close to the
present level of experimental sensitivity of . Such measurements
would signal new physics. We make the following points: (i) The mechanism at
work in neutral D decays could be indirect or direct CP violation (or both).
(ii) One can experimentally distinguish between these possibilities. (iii) If
the dominant CP violation is indirect, then there are clear predictions for
other modes. (iv) Tree-level direct CP violation in various known models is
constrained to be much smaller than . (v) SCS decays, unlike Cabibbo
favored or doubly Cabibbo suppressed decays, are sensitive to new contributions
from QCD penguin operators and especially from chromomagnetic dipole operators.
This point is illustrated with supersymmetric gluino-squark loops, which can
yield direct CP violating effects of .Comment: 36 pages, 5 figure
Aneurismas Gigantes do Septo Interauricular Simulando Massas Quísticas. Dois Casos com Opções Terapêuticas Diferentes
With the recent technical improvement in echocardiography imaging (second harmonics) the number of interatrial septum aneurysms (ASA) increased and are easily recognized. We assist to an overdiagnosing number of cases and diagnostic criteria emerged to face this problem. In the great majority of the cases ASA are small and inoffensive, but as ASA is considered a risk factor for cardioembolism when associated with persistence of foramen oval (PFO), an examination by transesophageal echocardiography (TEE) for exclusion of PFO makes the sense and is a common testing in patients with cryptogenic stroke. Besides these frequent ASA, other forms exist; the authors describe two cases of uncommon and huge ASA, one mimicking a right atrial tumor and the other a quistic, hipoechoic mass. The first case was associated with mitral stenosis and was submitted to surgery and the second was closed with an Amplatzer occluder device usually used in atrial septal defect (ASD)
Impacto da Coartação da Aorta Reparada no Trabalho Miocárdico Ventricular Esquerdo
Aims: Myocardial strain analysis enables more precise assessment of cardiac performance but is relatively load dependent. New tools have been developed with afterload adjustment. Our objective was to assess myocardial work (MW) in patients with repaired aortic coarctation (rACo).
Methods: Prospective study of consecutive patients with rACo who underwent a routine transthoracic echocardiogram in 2018 and 2019 at our center. Patients with significant aortic valve disease, pacemaker, or other congenital heart diseases (except for mild bicuspid aortic valve disease) were excluded. Global longitudinal strain with two dimensional speckle tracking analysis and MW were obtained (GWI:Global Work Index; GCW: Global Constructive Work; GWW: Global Wasted Work; GWE: Global Work Efficiency). Blood pressure was measured in the patient's right arm.
Results: We included 42 patients in the analysis, mean age of 37±10 years, 38% males. In this group, 52% had hypertension and 64% had a concomitant bicuspid aortic valve. In comparison to previously published reference values, patients with rACo had significantly lower GWI (1807 vs. 1896 mmHg%) and GCW (2173 vs. 2232 mmHg%) (p0.594). Neither age nor gender were independent predictors.
Conclusions: In patients with rACo, there are some signs of left ventricular dysfunction with a reduction in GCW and GWI and with preserved GWE, despite normal ejection fraction and strain.info:eu-repo/semantics/publishedVersio
Real CP violation in a simple extension of the standard model
I present a simple three-Higgs-doublet extension of the standard model in
which real CP violation takes place. The strong CP problem is attenuated by
this model.Comment: 8 page
- …