6,961 research outputs found
Looking for the Top-squark at the Tevatron with four jets
The scalar partner of the top quark is relatively light in many models of
supersymmetry breaking. We study the production of top squarks (stops) at the
Tevatron collider and their subsequent decay through baryon-number violating
couplings such that the final state contains no leptons. Performing a
detector-level analysis, we demonstrate that, even in the absence of leptons or
missing energy, stop masses upto 210 \gev/c^2 can be accessible at the
Tevatron.Comment: 4 pages, 4 embedded figures, RevTe
Domain walls in Born-Infeld-dilaton background
We study the dynamics of domain walls in Einstein-Born-Infeld-dilaton theory.
Dilaton is non-trivially coupled with the Born-Infeld electromagnetic field. We
find three different types of solutions consistent with the dynamic domain
walls. For every case, the solutions have singularity. Further more, in these
backgrounds, we study the dynamics of domain walls. We qualitatively plot
various form of the bulk metrics and the potential encountered by the domain
walls. In many cases, depending upon the value of the parameters, the domain
walls show bouncing universe and also undergo inflationary phase followed by
standard decelerated expansion.Comment: 18 pages,6 figures,latex, References added, Some points clarifie
Observable signals in a string inspired axion-dilaton background and Randall-Sundrum scenario
Rotation angle of the plane of polarization of the distant galactic radio
waves has been estimated in a string inspired axion-dilaton background. It is
found that the axion,dual to the field strength of the second rank
antisymmetric massless Kalb-Ramond field in the string spectrum, produces a
wavelength independent optical rotation which is much larger than that produced
by the dilaton. Detection of such rotation has been reported in some recent
cosmological experiments. The observed value has been compared with our
estimated theoretical value following various cosmological constraints. The
effects of warped extra dimensions in a braneworld scenario on such an optical
rotation have been investigated.Comment: 17 Pages, Latex, article revised, To appear in Physical Review
Electronic spectra of linear HCH and cumulene carbene HC
The transition of linear HCH
(A) has been observed in a neon matrix and gas phase. The assignment is based
on mass-selective experiments, extrapolation of previous results of the longer
HCH homologues, and density functional and multi-state CASPT2
theoretical methods. Another band system starting at 303 nm in neon is assigned
as the transition of the cumulene carbene
pentatetraenylidene HC (B).Comment: 7 pages, 4 figures, 5 table
The interplay between the charged Higgs and squark-gluino events at the LHC
In some extensions of the standard model with extended Higgs sectors, events
from new particle production may pass the selection criteria for Higgs search
in different channels at the LHC - 14 TeV and mimic Higgs signals. This
intriguing possibility is illustrated by PYTHIA based simulations using several
representative points in the parameter space of the minimal supersymmetric
standard model (MSSM) including a point in the minimal supergravity model
consistent with the Dark matter (DM) relic density data. Our simulations
explore the interplay between the charged Higgs signal and typical
squark-gluino events. We argue that the standard selections like the one based
on the polarization properties of the 's from charged Higgs decay, though
adequate for handling the SM background, may not be very efficient in the
presence of SUSY backgrounds. We then propose an alternative search strategy
based on pure kinematics which sufficiently controls both the SM and the MSSM
backgrounds. For charged Higgs masses () in the deep decoupling regime
(600 GeV \lsim m_{H^{\pm}} \lsim 800 GeV) this method works well and extends
the LHC reach close to 800 GeV for an integrated luminosity of 30
with or without the SUSY background. For a lighter charged Higgs a judicious
combination of the old selections and some of the cuts proposed by us may
disentangle the Higgs signal from the squark-gluino backgrounds quite
effectively
High-k HfO2 based metal-oxide-semiconductor devices using silicon and silicon carbide semiconductor
In this paper we have calculated the flatband capacitance (CFB) for high-k dielectric material hafnia oxide (HfO2) as an insulator and silicon carbide (SiC) as a semiconductor material for metal-oxide-semiconductor (MOS) devices. We simulate the capacitance-voltage (C-V) characteristics of the MOS devices with ultrathin oxide using ATLAS, a commercially available TCAD tool from SILVACO. The tool has investigated the effect on C-V characteristics of different oxide thickness and doping concentration of SiO2 and HfO2 as insulators and Si and SiC as semiconductor based MOS devices. Excellent agreement was observed over a wide range of oxide thickness and substrate doping for the materials. The C-V characteristics of different polytype of SiC semiconductor also studied for n-type MOS devices.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2789
Constraining the Randall-Sundrum modulus in the light of recent PVLAS data
Recent PVLAS data put stringent constraints on the measurement of
birefringence and dichroism of electromagnetic waves travelling in a constant
and homogeneous magnetic field. There have been theoretical predictions in
favour of such phenomena when appropriate axion-electromagnetic coupling is
assumed. Origin of such a coupling can be traced in a low energy string action
from the requirement of quantum consistency. The resulting couplings in such
models are an artifact of the compactification of the extra dimensions present
inevitably in a string scenario. The moduli parameters which encode the compact
manifold therefore play a crucial role in determining the axion-photon
coupling. In this work we examine the possible bounds on the value of compact
modulus that emerge from the experimental limits on the coupling obtained from
the PVLAS data. In particular we focus into the Randall-Sundrum (RS) type of
warped geometry model whose modulus parameter is already restricted from the
requirement of the resolution of gauge hierarchy problem in connection with the
mass of the Higgs. We explore the bound on the modulus for a wide range of the
axion mass for both the birefringence and the dichroism data in PVLAS. We show
that the proposed value of the modulus in the RS scenario can only be
accommodated for axion mass \gsim 0.3 eV.Comment: 26 pages, 1 figure, LaTex; added references, typos corrected. Minor
changes in the text, a comment added in the Conclusio
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