5,351 research outputs found
Supersymmetric Higgs Boson Decays in the MSSM with Explicit CP Violation
Decays into neutralinos and charginos are among the most accessible
supersymmetric decay modes of Higgs particles in most supersymmetric extensions
of the Standard Model. In the presence of explicitly CP--violating phases in
the soft breaking sector of the theory, the couplings of Higgs bosons to
charginos and neutralinos are in general complex. Based on a specific benchmark
scenario of CP violation, we analyze the phenomenological impact of explicit CP
violation in the Minimal Supersymmetric Standard Model on these Higgs boson
decays. The presence of CP--violating phases could be confirmed either directly
through the measurement of a CP--odd polarization asymmetry of the produced
charginos and neutralinos, or through the dependence of CP--even quantities
(branching ratios and masses) on these phases.Comment: 14 pages, latex, 4 eps figure
Large eddy simulation and laboratory experiments on the decay of grid wakes in strongly stratified flows
A detailed analysis of the flow structure resulting from the combination
of turbulence and internal waves is carried out and visualized by means
of the Schlieren method on waves in a strongly stratified fluid at the Laboratory of the IPM in Moscow. The joint appearance of the more regular internal wave oscillations and the small-scale turbulence that is confined vertically to the Ozmidov length scale favours the use of a simple geometrical analysis to investigate their time-space span and evolution. This provides useful information on the collapse of internal wave breaking processes in the ocean and the atmosphere. The measurements were performed under a variety of linear stratifications and different grid forcing scales, combining the grid wake and velocity shear. A numerical simulation using LES on the passage of a single bar in a linearly stratified fluid medium has been compared with the experiments identifying the different influences of the environmental
agents on the actual effective vertical diffusion of the wakes. The equation of state, which connects the density and salinity, is assumed to be linear, with the coefficient of the salt contraction being included into the definition of salinity or heat. The characteristic internal waves as well as the entire beam width are related to the diameter of the bar, the Richardson number and the peak-to-peak value of oscillations. The ultimate frequency of the infinitesimal periodic internal waves is limited by the maximum buoyancy frequency relating the decrease in the vertical scale with the anisotropy of the velocity turbulent r.m.s. velocity.Peer ReviewedPreprin
Industrial Applications of Laser Neutron Source
The industrial applications of the intense neutron source have been widely explored because of the unique features of the neutron-matter interaction. Usually, intense neutron sources are assembled with fission reactors or high energy ion accelerators. The big size and high cost of these systems are the bottle neck to promote the industrial applications of intense neutrons. In this paper, we propose the compact laser driven neutron source for the industrial application. As the first step of our project for the versatile applications of laser driven neutron source, Li-neutron and/or Li-proton interactions have been investigated for the application to the development of Li battery
Uniqueness of static decompositions
We classify static manifolds which admit more than one static decomposition
whenever a condition on the curvature is fullfilled. For this, we take a
standard static vector field and analyze its associated one parameter family of
projections onto the base. We show that the base itself is a static manifold
and the warping function satisfies severe restrictions, leading us to our
classification results. Moreover, we show that certain condition on the
lightlike sectional curvature ensures the uniqueness of static decomposition
for Lorentzian manifolds.Comment: 14 page
Hydrodynamics in 1+1 dimensions with gravitational anomalies
The constraints imposed on hydrodynamics by the structure of gauge and
gravitational anomalies are studied in two dimensions. By explicit integration
of the consistent gravitational anomaly, we derive the equilibrium partition
function at second derivative order. This partition function is then used to
compute the parity-violating part of the covariant energy-momentum tensor and
the transport coefficients.Comment: 9 pages, JHEP format.v2; added comments and references, matching
published versio
S-matrix poles and the second virial coefficient
For cutoff potentials, a condition which is not a limitation for the
calculation of physical systems, the S-matrix is meromorphic. We can express it
in terms of its poles, and then calculate the quantum mechanical second virial
coefficient of a neutral gas.
Here, we take another look at this approach, and discuss the feasibility,
attraction and problems of the method. Among concerns are the rate of
convergence of the 'pole' expansion and the physical significance of the
'higher' poles.Comment: 20 pages, 8 tables, submitted to J. Mol. Phy
The monoclinic crystal structure of -RuCl and the zigzag antiferromagnetic ground state
The layered honeycomb magnet alpha-RuCl3 has been proposed as a candidate to
realize a Kitaev spin model with strongly frustrated, bond-dependent,
anisotropic interactions between spin-orbit entangled jeff=1/2 Ru4+ magnetic
moments. Here we report a detailed study of the three-dimensional crystal
structure using x-ray diffraction on untwinned crystals combined with
structural relaxation calculations. We consider several models for the stacking
of honeycomb layers and find evidence for a crystal structure with a monoclinic
unit cell corresponding to a stacking of layers with a unidirectional in-plane
offset, with occasional in-plane sliding stacking faults, in contrast with the
currently-assumed trigonal 3-layer stacking periodicity. We report electronic
band structure calculations for the monoclinic structure, which find support
for the applicability of the jeff=1/2 picture once spin orbit coupling and
electron correlations are included. We propose that differences in the
magnitude of anisotropic exchange along symmetry inequivalent bonds in the
monoclinic cell could provide a natural mechanism to explain the spin gap
observed in powder inelastic neutron scattering, in contrast to spin models
based on the three-fold symmetric trigonal structure, which predict a gapless
spectrum within linear spin wave theory. Our susceptibility measurements on
both powders and stacked crystals, as well as neutron powder diffraction show a
single magnetic transition at TN ~ 13K. The analysis of the neutron data
provides evidence for zigzag magnetic order in the honeycomb layers with an
antiferromagnetic stacking between layers. Magnetization measurements on
stacked single crystals in pulsed field up to 60T show a single transition
around 8T for in-plane fields followed by a gradual, asymptotic approach to
magnetization saturation, as characteristic of strongly anisotropic exchange
interactions.Comment: 13 pages, 9 figures, published in Physical Review
Patterns in the Fermion Mixing Matrix, a bottom-up approach
We first obtain the most general and compact parametrization of the unitary
transformation diagonalizing any 3 by 3 hermitian matrix H, as a function of
its elements and eigenvalues. We then study a special class of fermion mass
matrices, defined by the requirement that all of the diagonalizing unitary
matrices (in the up, down, charged lepton and neutrino sectors) contain at
least one mixing angle much smaller than the other two. Our new parametrization
allows us to quickly extract information on the patterns and predictions
emerging from this scheme. In particular we find that the phase difference
between two elements of the two mass matrices (of the sector in question)
controls the generic size of one of the observable fermion mixing angles: i.e.
just fixing that particular phase difference will "predict" the generic value
of one of the mixing angles, irrespective of the value of anything else.Comment: 29 pages, 3 figures, references added, to appear in PR
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