2,326 research outputs found
Exploring CP Violation in the MSSM
We explore the prospects for observing CP violation in the minimal
supersymmetric extension of the Standard Model (MSSM) with six CP-violating
parameters, three gaugino mass phases and three phases in trilinear soft
supersymmetry-breaking parameters, using the CPsuperH code combined with a
geometric approach to maximize CP-violating observables subject to the
experimental upper bounds on electric dipole moments. We also implement
CP-conserving constraints from Higgs physics, flavour physics and the upper
limits on the cosmological dark matter density and spin-independent scattering.
We study possible values of observables within the constrained MSSM (CMSSM),
the non-universal Higgs model (NUHM), the CPX scenario and a variant of the
phenomenological MSSM (pMSSM). We find values of the CP-violating asymmetry
A_CP in b -> s gamma decay that may be as large as 3%, so future measurements
of A_CP may provide independent information about CP violation in the MSSM. We
find that CP-violating MSSM contributions to the B_s meson mass mixing term
Delta M_Bs are in general below the present upper limit, which is dominated by
theoretical uncertainties. If these could be reduced, Delta M_Bs could also
provide an interesting and complementary constraint on the six CP-violating
MSSM phases, enabling them all to be determined experimentally, in principle.
We also find that CP violation in the h_{2,3} tau+ tau- and h_{2,3} tbar t
couplings can be quite large, and so may offer interesting prospects for future
pp, e+ e-, mu+ mu- and gamma gamma colliders.Comment: 36 pages, 32 figure
Effect of sports vision exercise on visual perception and reading performance in 7- to 10-year-old developmental dyslexic children
The presented study was aimed at identifying for the first time the influence of sports vision exercises on fundamental motor skills and cognitive skills of 7- to 10-year-old developmental dyslexic Persian children. A pretest - posttest quasi-experimental study was conducted. The statistical population of this study was 7- to 10-year-old dyslexic children referring to two centres of learning disorder in the city of Isfahan. Twenty two of these children were selected using available and purposive sampling from the statistical population and were randomly assigned into two groups of experimental and control. The former (experimental group) participated in sports vision exercise courses for 12 weeks (3 one hr sessions per week) and the latter (control group) continued their routine daily activities during the exercise. Before the beginning and at the end of the exercise, Gardner’s test of visual perception test - revised and Dehkhoda’s reading skills test was administered to both groups. The results showed that the sports vision exercises increases motor skills, visual perceptual skills and reading skills in developmental dyslexic children. Based on the results of the presented study it was concluded that sports vision exercises can be used for fundamental and cognitive skills of developmental dyslexic children
QCD Corrections in two-Higgs-doublet extensions of the Standard Model with Minimal Flavor Violation
We present the QCD corrections to R_b and to the Delta B=1 effective
Hamiltonian in models with a second Higgs field that couples to the quarks
respecting the criterion of Minimal Flavor Violation, thus belonging either to
the (1,2)_1/2 or to the (8,2)_1/2 representation of SU(3)xSU(2)xU(1). After the
inclusion of the QCD corrections, the prediction for R_b becomes practically
insensitive to the choice of renormalization scheme for the top mass, which for
the type-I and type-II models translates in a more robust lower bound on
tan(beta). The QCD-corrected determinations of Rb and BR(B->Xs gamma) are used
to discuss the constraints on the couplings of a (colored) charged Higgs boson
to top and bottom quarks.Comment: 19 pages, 7 figures. v2: version published in Phys. Rev. D, with
additional reference and not
Ultra high data rate CMOS FEs
The availability of numerous mm-wave frequency bands for wireless communication has motived the exploration of multi-band and multi-mode integrated components and systems in the main stream CMOS technology. This opportunity has faced the RF designer with the transition between schematic and layout. Modeling the performance of circuits after layout and taking into account the parasitic effects resulting from the layout are two issues that are more important and influential at high frequency design. Performaning measurements using on-wafer probing at 60GHz has its own complexities. The very short wave-length of the signals at mm-wave frequencies makes the measurements very sensitiv to the effective length and bending of the interfaces. This paper presents different 60GHz corner blocks, e.g. Low Noise Amplifier, Zero IF mixer, Phase-Locked Loop, A Dual-Mode Mm-Wave Injection-Locked Frequency Divider and an active transformed power amplifiers implemented in CMOS technologies. These results emphasize the feasibility of the realization 60GHZ integrated components and systems in the main stream CMOS technology
Ultra high data rate CMOS front ends
The availability of numerous mm-wave frequency bands for wireless communication has motivated the exploration of multi-band and multi-mode integrated components and systems in the main stream CMOS technology. This opportunity has faced the RF designer with the transition between schematic and layout. Modeling the performance of circuits after layout and taking into account the parasitic effects resulting from the layout are two issues that are more important and influential at high frequency design. Performing measurements using on-wafer probing at 60 GHz has its own complexities. The very short wave-length of the signals at mm-wave frequencies makes the measurements very sensitive to the effective length and bending of the interfaces. This paper presents different 60 GHz corner blocks, e.g. Low Noise Amplifier, Zero IF mixer, Phase-Locked Loop, a Dual-Mode Mm-Wave Injection-Locked Frequency Divider and an active transformed power amplifiers implemented in CMOS technologies. These results emphasize the feasibility of the realization 60 GHZ integrated components and systems in the main stream CMOS technology
Estimating the annihilation decay B_s -> rho gamma with factorization
The branching ratio for the rare two-body B_s -> rho gamma decay is
calculated using the factorization assumption. This transition is dominated by
the annihilation diagrams and, in principle, prone to receiving substantial
contributions from new physics. We estimate Br(B_s -> rho gamma) = 1.6 x 10^-9
within the Standard Model and investigate the sensitivity of this decay mode to
the effects of two new physics scenarios: vector quark model and supersymmetry.
Our results indicate that the shift in branching ratio is at most around 10%
with the addition of vector quarks and is negligibly small in the constrained
minimal supersymmetric extension of the Standard Model.Comment: 9 pages, 1 figur
Analysis, Design and Fabrication of centimeter-wave Dielectric Fresnel Zone Plate Lens and reflector
Fresnel lens has a long history in optics. This concept at non-optical
wavelengths is also applicable. In this paper we report design and fabrication
of a half and quarter wave dielectric Fresnel lens made of Plexiglas, and a
Fresnel reflector at 11.1 GHz frequency. We made two lenses and one reflector
at same frequency and compare their gain and radiation pattern to simulated
results. Some methods for better focusing action will be introduced
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