24,402 research outputs found
Asymptotic Methods in Non Linear Dynamics
This paper features and elaborates recent developments and modifications in
asymptotic techniques in solving differential equation in non linear dynamics.
These methods are proved to be powerful to solve weakly as well as strongly non
linear cases. Obtained approximate analytical solutions are valid for the whole
solution domain. In this paper, limitations of traditional perturbation methods
are illustrated with various modified techniques. Mathematical tools such as
variational approach, homotopy and iteration technique are discussed to solve
various problems efficiently. Asymptotic methods such as Variational Method,
modified Lindstedt-Poincare method, Linearized perturbation method, Parameter
Expansion method, Homotopy Perturbation method and Perturbation-Iteration
methods(singular and non singular cases) have been discussed in various
situations. Main emphasis is given on Singular perturbation method and WKB
method in various numerical problems.Comment: submit, to appear in Journal of Non Linear Science and Applications,
201
The role of trapped neutrino in dense stelllar matter and kaon condensation
We investigate the effect of neutrino trapping on kaon condensation process
and Equation of State (EOS) in a newly formed neutron star which is less than
several seconds old. Using nonlinear relativistic mean field model, we find
that the presence of neutrino shifts the threshold for kaon condensation and
muon production to much higher density. We also studied the energy density and
pressure of the syst under trapped neutrino condition and found that it
stiffens the EOS of the system which may be responsible for the delayed
exploision mechanism of supernovae.Comment: 9 pages, 5 figure
Analytical Derivation of Three Dimensional Vorticity Function for wave breaking in Surf Zone
In this report, Mathematical model for generalized nonlinear three
dimensional wave breaking equations was de- veloped analytically using fully
nonlinear extended Boussinesq equations to encompass rotational dynamics in
wave breaking zone. The three dimensional equations for vorticity distributions
are developed from Reynold based stress equations. Vorticity transport
equations are also developed for wave breaking zone. This equations are basic
model tools for numerical simulation of surf zone to explain wave breaking
phenomena. The model reproduces most of the dynamics in the surf zone. Non
linearity for wave height predictions is also shown close to the breaking both
in shoaling as well as surf zone. Keyword Wave breaking, Boussinesq equation,
shallow water, surf zone. PACS : 47.32-yComment: arXiv admin note: substantial text overlap with arXiv:physics/050307
SUSY Dark Matter: Closing The Parameter Space
We consider here the constraints in SUGRA models on the SUSY parameter space
due to current experimental bounds on the light Higgs mass m_h, the b-> s gamma
decay, the amount of neutralino cold dark matter Omega h^2, and the muon
magnetic moment. Models with universal soft breaking (mSUGRA) and non-universal
gaugino or Higgs masses at M_G are examined. For mSUGRA, the m_h, b->s gamma
and Omega h^2 constraints imply a lower bound on the gaugino mass of
m_{1/2}>~300GeV implying the gluino and squarks have mass >~700GeV, and the
neutralino >~120GeV. The current status of the Brookhaven muon g - 2 experiment
is reviewed, and if the Standard Model (SM) contribution evaluated using the
e^+ + e^- data is correct, a 2 sigma bound on the deviation of experiment from
the SM produces an upper bound on m_{1/2} that eliminates the "focus point"
regions of parameter space. Dark matter (DM) detection cross sections range
from 5\times10^{-8} pb to 5\times10^{-10} pb which would be accessible to
future planned detectors. The SUSY decay B_s->\mu^+ +\mu^- is seen to be
accessible to the Tevatron Run 2B with 15 fb^{-1} luminosity for tanbeta >~30.
The most favorable signals of SUSY for linear colliders are stau pair
production and neutralino pair production, though it will require an 800GeV
machine to cover the full parameter space. Non-universal models can modify some
of the above results. Thus a non-universal (heavier) gluino mass at M_G can
significantly reduce the lower bound constraints of b\to s gamma and m_h giving
rise to a lighter SUSY spectrum. A heavier up Higgs mass can open an additional
region with allowed relic density arising from annihilation via the s-channel Z
diagram with an O(10) larger DM detector cross section.Comment: 14 pages, latex, 13 figures, Talk at conference Beyond the Desert
'02, June, 2002, Oulu, Finlan
Dark matter and Consequences of SUSY
We examine here the constraints from the amount of relic density of
neutralino dark matter and other experiments have on the SUSY parameter space
for the mSUGRA model and for models with non-universal soft breaking at the GUT
scale. In mSUGRA, the allowed amount of dark matter restricts the SUSY
parameter space to a narrow band in m_0 - m_{1/2} (except at very large
\tan\beta). The Higgs mass and b-> s\gamma constraints produce a lower bound of
m_{1/2}>~{\sim} 300GeV and if the muon magnetic moment anomaly can be
interpreted as a 3\sigma deviation from the Standard Model, one also obtains an
upper bound of m_{1/2} <~900 GeV, making the SUSY spectrum well accessible to
the LHC. The B_s->\mu \mu decay is seen to be accessible to the Tevatron Run2B
with 15 fb^{-1} for \tan\beta>~30. However, only parts of the spectrum will be
accessible to the NLC if it's energy is below 800GeV. Non-universal soft
breaking opens new regions of parameter space. Thus the m_{1/2} lower bound
constraint of b->s\gamma and also the Higgs mass can be reduced greatly if the
gluino mass is assumed larger at the GUT scale (allowing for a lighter gaugino
spectrum), and non-universal Higgs soft breaking masses at the GUT scale can
open new allowed regions at relatively low m_{1/2} and high m_0 where dark
matter detection cross sections may be increased by a factor of ten or more.Comment: 11 pages, latex, 10 figures, Plenary talk at SUSY02 (DESY, June
17-23, 2002
Generalized Set of Boussinesq equations for Surf Zone Region
In this report, generalized wave breaking equations are developed using three
dimensional fully nonlinear extended Boussinesq equations to encompass
rotational dynamics in wave breaking zone. The derivation for vorticity
distributions are developed from Reynold based stress equations.Comment: 12 pages, submitted to Coastal Engineerin
Dark Matter Detection Rates In SUGRA Models
Direct detection of Milky Way wimps are discussed within the framework of
R-parity conserving SUGRA models with grand unification at M_G. Two questions
are discussed: what SUGRA models can account for the DAMA data if this data is
confirmed, and is the full SUGRA parameter space accessible to future planned
detectors. Experimental constraints of the Higgs mass bound, the b-> s\gamma
bound, relic density constraints (including all co-annihilation channels), etc.
are imposed. In addition, the effect of the possible muon g - 2 anomaly are
examined. For mSUGRA, we find that the Higgs mass and b\to s\gamma constraint
puts a lower bound m_{1/2} > (300 - 400) GeV (i.e. m_{\tilde\chi^0_1} > (120 -
160) GeV) for \tan\beta < 50, and thus the largest theoretical
neutralino-proton cross sections still lie significantly below the DAMA 3\sigma
lower bound. (Predictions for \tan\beta> 50 become sensitive to the precise
value of m_t and m_b.) If in addition one imposes the muon anomaly constraint,
\mu must be positive and an upper bound of m_{1/2}< 850 GeV for \tan\beta < 50
is obtained. More generally, if \mu >0 and m_{1/2} < 1 TeV, the cross sections
are >~ 10^{-10} pb, and hence this parameter space would be mostly accessible
to planned high sensitivity detectors. For non-minimal SUGRA models, the cross
sections can be considerably larger, and a simple SU(5) model with
non-universal soft breaking in the Higgs and third generation is seen to give
cross sections in the DAMA range for \tan\beta >~ 15 with m_{\tilde\chi^0_1} >
80 GeV, and minimum cross sections >~10^{-10} pb for \mu > 0.Comment: 14 pages, latex, 8 figures, talk at COSMO-01, Rovaniemi, Finland,
August 29 - September 4, 200
Numerical Studies of Particle Laden Flow in Dispersed Phase
To better understand the hydrodynamic flow behavior in turbulence,
Particle-Fluid flow have been studied using our Direct Numerical(DNS) based
software DSM on MUSCL-QUICK and finite volume algorithm. The particle flow was
studied using Eulerian-Eulerian Quasi Brownian Motion(QBM) based approach. The
dynamics is shown for various particle sizes which are very relevant to spray
mechanism for Industrial applications and Bio medical applications.Comment: 9 pages, 12 Figures, submitted to International Journal for Numerical
Methods in Fluid
Yukawa Textures in Heterotic M-Theory
We examine the structure of the Yukawa couplings in the 11 dimensional
Horava-Witten M-theory based on non-standard embeddings. We find that the CKM
and quark mass hierarchies can be explained in M Theory without introducing
undue fine tuning. A phenomenological example is presented satisfying all CKM
and quark mass data requiring the 5-branes cluster near the second orbifold
plane, and that the instanton charges of the physical orbifold plane vanish.
The latter condition is explicitly realized on a Calabi-Yau manifold with del
Pezzo base dP_7.Comment: 3 pages, latex, talk at DPF 2000, Columbus, OH, August 9-12, 200
Yukawa Textures in Horava-Witten M-Theory
Recent advances in 11 dimensional Horava-Witten M-theory based on
non-standard embeddings with torus fibered Calabi-Yau manifolds have allowed
the construction of three generation models with Wilson line breaking to the
Standard Model gauge symmetry. Central to these constructions is the existence
of a set of 5-branes in the bulk. We examine within this framework the general
structure of the matter Yukawa couplings and show that M-theory offers an
alternate possible way of achieving the CKM and quark mass hierarchies without
introducing undue fine tuning or (as in conventional analysis) small parameters
raised to high powers. A phenomenological example is presented in accord with
all CKM and quark mass data requiring mainly that the 5-branes cluster near the
second orbifold plane, and that the instanton charges of the physical orbifold
plane vanish. An explicit example of a three generation model with vanishing
physical plane instanton charges based on a torus fibered Calabi-Yau three fold
with a del Pezzo base and Wilson line breaking is constructed.Comment: 28 pages, Revte
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