10,060 research outputs found
Production and decays of supersymmetric Higgs bosons in spontaneously broken R-parity
We study the mass spectra, production and decay properties of the lightest
supersymmetric CP-even and CP-odd Higgs bosons in models with spontaneously
broken R-parity (SBRP). We compare the resulting mass spectra with expectations
of the Minimal Supersymmetric Standard Model (MSSM), stressing that the model
obeys the upper bound on the lightest CP-even Higgs boson mass. We discuss how
the presence of the additional scalar singlet states affects the Higgs
production cross sections, both for the Bjorken process and the "associated
production". The main phenomenological novelty with respect to the MSSM comes
from the fact that the spontaneous breaking of lepton number leads to the
existence of the majoron, denoted J, which opens new decay channels for
supersymmetric Higgs bosons. We find that the invisible decays of CP-even
Higgses can be dominant, while those of the CP-odd bosons may also be sizeable.Comment: 21 pages, 8 figures; minor changes, final version for publicatio
Effective penetration length and interstitial vortex pinning in superconducting films with regular arrays of defects
In order to compare magnetic and non-magnetic pinning we have nanostructured
two superconducting films with regular arrays of pinning centers: Cu
(non-magnetic) dots in one case, and Py (magnetic) dots in the other. For low
applied magnetic fields, when all the vortices are pinned in the artificial
inclusions, magnetic dots prove to be better pinning centers, as has been
generally accepted. Unexpectedly, when the magnetic field is increased and
interstitial vortices appear, the results are very different: we show how the
stray field generated by the magnetic dots can produce an effective reduction
of the penetration length. This results in strong consequences in the transport
properties, which, depending on the dot separation, can lead to an enhancement
or worsening of the transport characteristics. Therefore, the election of the
magnetic or non-magnetic character of the pinning sites for an effective
reduction of dissipation will depend on the range of the applied magnetic
field.Comment: 10 pages, 3 figure
Degenerate neutrinos from a supersymmetric A_4 model
We investigate the supersymmetric A_4 model recently proposed by Babu, Ma and
Valle. The model naturally gives quasi-degenerate neutrinos that are bi-largely
mixed, in agreement with observations. Furthermore, the mixings in the quark
sector are constrained to be small, making it a complete model of the flavor
structure. Moreover, it has the interesting property that CP-violation in the
leptonic sector is maximal (unless vanishing). The model exhibit a close
relation between the slepton and lepton sectors and we derive the slepton
spectra that are compatible with neutrino data and the present bounds on
flavor-violating charged lepton decays. The prediction for the branching ratio
of the decay tau -> mu gamma has a lower limit of 10^{-9}. In addition, the
overall neutrino mass scale is constrained to be larger than 0.3 eV. Thus, the
model will be tested in the very near future.Comment: 11 pages, 6 figures. Talk given at the International Workshop on
Astroparticle and High Energy Physics (AHEP), Valencia, Spain, 14-18 Oct.
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Minimal supergravity radiative effects on the tri-bimaximal neutrino mixing pattern
We study the stability of the Harrison-Perkins-Scott (HPS) mixing pattern,
assumed to hold at some high energy scale, against supersymmetric radiative
corrections. We work in the framework of a reference minimal supergravity model
(mSUGRA) where supersymmetry breaking is universal and flavor-blind at
unification. The radiative corrections considered include both RGE running as
well as threshold effects. We find that in this case the solar mixing angle can
only increase with respect to the HPS reference value, while the atmospheric
and reactor mixing angles remain essentially stable. Deviations from the solar
angle HPS prediction towards lower values would signal novel contributions from
physics beyond the simplest mSUGRA model.Comment: 13 pages, 3 figures; added reference; final version for publicatio
Radial power-like potentials: from the Bohr-Sommerfeld -state energies to the exact ones
Following our previous study of the Bohr-Sommerfeld (B-S) quantization
condition for one-dimensional case (del Valle \& Turbiner (2021) \cite{First}),
we extend it to -dimensional power-like radial potentials. The B-S
quantization condition for -states of the -dimensional radial
Schr\"odinger equation is proposed. Based on numerical results obtained for the
spectra of power-like potentials, with , the
correctness of the proposed B-S quantization condition is established for
various dimensions . It is demonstrated that by introducing the {\it WKB
correction} (supposedly coming from the higher order WKB terms) into
the r.h.s. of the B-S quantization condition leads to the so-called {\it exact
WKB quantization condition}, which reproduces the exact energies, while
remains always very small. For (any integer ) and for
(at ) the WKB correction : for states the B-S spectra
coincides with the exact ones.
Concrete calculations for physically important cases of linear, cubic,
quartic, and sextic oscillators, as well as Coulomb and logarithmic potentials
in dimensions are presented. Radial quartic anharmonic oscillator is
considered briefly.Comment: 15 pages, 4 figures, 4 tables; extended, some typos fixed, to be
published in IJMP
Radial Anharmonic Oscillator: Perturbation Theory, New Semiclassical Expansion, Approximating Eigenfunctions. II. Quartic and Sextic Anharmonicity Cases
In our previous paper I (del Valle--Turbiner, Int. J. Mod. Phys. A34,
1950143, 2019) it was developed the formalism to study the general
-dimensional radial anharmonic oscillator with potential . It was based on the Perturbation Theory (PT) in
powers of (weak coupling regime) and in inverse, fractional powers of
(strong coupling regime) in both -space and in -space, respectively.
As the result it was introduced - the Approximant - a locally-accurate uniform
compact approximation of a wave function. If taken as a trial function in
variational calculations it has led to variational energies of unprecedented
accuracy for cubic anharmonic oscillator. In this paper the formalism is
applied to both quartic and sextic, spherically-symmetric radial anharmonic
oscillators with two term potentials ,
respectively. It is shown that a two-parametric Approximant for quartic
oscillator and a five-parametric one for sextic oscillator for the first four
eigenstates used to calculate the variational energy are accurate in 8-12
figures for any and , while the relative deviation
of the Approximant from the exact eigenfunction is less than for any
.Comment: 52 pages, 17 figures, 3 appendice
Superconducting/magnetic three state nanodevice for memory and reading applications
We present a simple nanodevice that can operate in two modes: i) three-state
memory and ii) reading device. The nanodevice is fabricated with an array of
ordered triangular-shaped nanomagnets embedded in a superconducting thin film.
The input signal is ac current and the output signal is dc voltage. Vortex
ratchet effect in combination with out of plane magnetic anisotropy of the
nanomagnets is the background physics which governs the nanodevice performance.Comment: 10 pages, 4 figure
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