4,915 research outputs found
Hot Nuclear Matter : A Variational Approach
We develop a nonperturbative technique in field theory to study properties of
infinite nuclear matter at zero temperature as well as at finite temperatures.
Here we dress the nuclear matter with off-mass shell pions. The techniques of
thermofield dynamics are used for finite temperature calculations. Equation of
state is derived from the dynamics of the interacting system in a self
consistent manner. The transition temperature for nuclear matter appears to be
around 15 MeV.Comment: 16 pages, IP/BBSR/91-3
Neutron matter - Quark matter phase transition and Quark star
We consider the neutron matter quark matter phase transition along with
possible existence of hybrid quark stars. The equation of state for neutron
matter is obtained using a nonperturbative method with pion dressing of the
neutron matter and an analysis similar to that of symmetric nuclear matter. The
quark matter sector is treated perturbatively in the small distance domain. For
bag constant =148 MeV, a first order phase transition is seen. In the
context of neutron quark hybrid stars, Tolman-Oppenheimer-Volkoff equations are
solved using the equations of state for quark matter and for neutron matter
with a phase transition as noted earlier. Stable solutions for such stars are
obtained with the Chandrasekhar limit as 1.58 and radius around 10
km. The bulk of the star is quark matter with a thin crust of neutron matter of
less than a kilometer.Comment: 28 pages including 9 figures, Revtex, IP/BBSR/92-8
Vanishing corrections on the intermediate scale and implications for unification of forces
In two-step breaking of a class of grand unified theories including SO(10),we
prove a theorem showing that the scale where the Pati-Salam gauge
symmetry with parity breaks down to the standard gauge group,has vanishing
corrections due to all sources emerging from higher scales such as
the one-loop and all higher loop effects,the GUT-threshold,gravitational
smearing,and string threshold effects. Implications of such a scale for the
unification of gauge couplings with small Majorana neutrino masses are
discussed.In string inspired SO(10) we show that ,needed for neutrino masses,with the GUT scale can
be realized provided certain particle states in the predicted spectum are
light.Comment: 21 pages, Late
A Blind Signature Scheme using Biometric Feature Value
Blind signature has been one of the most charming research fields of public key cryptography through which authenticity, data integrity and non-repudiation can be verified. Our research is based on the blind signature schemes which are based on two hard problems – Integer factorization and discrete logarithm problems. Here biological information like finger prints, iris, retina DNA, tissue and other features whatever its kind which are unique to an individual are embedded into private key and generate cryptographic key which consists of private and public key in the public key cryptosystem. Since biological information is personal identification data, it should be positioned as a personal secret key for a system. In this schemes an attacker intends to reveal the private key knowing the public key, has to solve both the hard problems i.e. for the private key which is a part of the cryptographic key and the biological information incorporated in it. We have to generate a cryptographic key using biometric data which is called biometric cryptographic key and also using that key to put signature on a document. Then using the signature we have to verify the authenticity and integrity of the original message. The verification of the message ensures the security involved in the scheme due to use of complex mathematical equations like modular arithmetic and quadratic residue as well
Observational constraints and some toy models in gravity with bulk viscous fluid
The standard formulation of general relativity fails to describe some recent
interests in the universe. It impels us to go beyond the standard formulation
of gravity. The gravity theory is an interesting modified theory of
gravity, where the gravitational interaction is driven by the nonmetricity .
This study aims to examine the cosmological models with the presence of bulk
viscosity effect in the cosmological fluid within the framework of
gravity. We construct three bulk viscous fluid models, i.e. (i) for the first
model, we assuming the Lagrangian as linear dependence on , (ii) for
the second model the Lagrangian as a polynomial functional form, and
(iii) the Lagrangian as a logarithmic dependence on . Furthermore, we
use 57 points of Hubble data and 1048 Pantheon dataset to constraint the model
parameters. Then, we discuss all the energy conditions for each model, which
helps us to test the self-consistency of our models. Finally, we present the
profiles of the equation of state parameters to test the models' present
status.Comment: 13 pages,9 figures. Comments are Welcom
Performance Evaluation of Multimodal Transportation Systems
AbstractConnectivity of more than one mode to a line haul in an urban area constitutes the multimodal transport system of the city. In this paper New Delhi has been taken up as a case study to evaluate performance of multimodal transportation system (MMTS), where metro became main mode in routine public transport trips. Public transport in Delhi carries only about 60% of total vehicular person trips as against 80% of the expected population size of the city. The present bus services, metro rail and IRBT (Integrated Rail-cum-Bus Transit), if implemented as planned together are estimated to carry about 15 million trips per day by 2021. Since, all the public transport trips are multimodal, it is necessary to evaluate the performance of multimodal transportation systems. The study is divided into two phases. In the first phase, the study of travel time elements (access time, transfer time, waiting time, line-haul time, and egress time) is done. Next, the influence of access and egress times on the total travel time is examined. Use is made of a comprehensive commuter travel diary to collect detail travel time estimates. A representative commuter survey, with 460 respondents, is drawn on platform at each station of Red Line and Yellow Line (Kashmiri Gate – Saket) Delhi Metro. Implementing the Second phase of study, performance measures such as Travel Time Ratio, Level of Service, Interconnectivity Ratio, Passenger Waiting Index, and Running Index were evaluated. Interconnectivity ratio (proportion of access and egress time w.r.t total travel time) for various combinations such as Mixed-Metro-Mixed, Walk-Metro-Walk, Walk-Metro-Bus and Walk- Bus-Walk has been observed. Travel Time (defined as the time differential between private transport and public transport) ratio shows much variation with trip direction, time of day, mode used, and distance travelled, etc.,. Level of Service Indicator (Out- of-vehicle Travel Time/In-Vehicle Travel Time) ratio inferred that people spends more time out-of-vehicle as compared to that of in-vehicle. Access time, transfer time, waiting time and egress time are the most important and complex travel time elements that transport systems should consider improving its efficiency and modal share. The results can be used in planning catchment area of public transport. Access and egress (together with waiting and transfer times) appear as factors that affect effectiveness and performance of a multimodal transportation system to a larger extent as unacceptable distances are likely to reduce ridership patronage. At the same time, there are key deciding factors when a trip originates as to whether the commuter shall choose public transit over personal mode of travel
Proton decay and new contribution to neutrino-less double beta decay in SO(10) with low-mass Z-prime boson, observable n-nbar oscillation, lepton flavor violation, and rare kaon decay
Conventionally for observable oscillation through Pati-Salam
intermediate gauge symmetry in , the canonical seesaw mechanism is also
constrained by GeV which yields light neutrino masses
much larger than the neutrino oscillation data. Recently, this difficulty has
been evaded via inverse seesaw mechanism, but with proton lifetime far beyond
the experimentally accessible limits. In the present work, adopting the view
that we may have only a TeV scale gauge boson, we show how a class
of non-SUSY models allow experimentally verifiable proton lifetime and
the new contributions to neutrinoless double beta decay in the
channel, lepton flavor violating branching ratios, observable
oscillation, and lepto-quark gauge boson mediated rare kaon decays. The
occurrence of Pati-Salam gauge symmetry with unbroken D-parity and two gauge
couplings at the highest intermediate scale guarantees precision unification in
such models. This symmetry also ensures vanishing GUT threshold uncertainy on
or on the highest intermediate scale. Although the proton
lifetime prediction is brought closer to the ongoing search limits with GUT
threshold effects in the minimal model, no such effects are needed in a
non-minimal model. We derive a new analytic expression for the
decay half-life and show how the existing experimental limits impose the lower
bound on the lightest of the three heavy sterile neutrino masses, GeV. We also derive a new lower bound on the lepto-quark gauge boson
mass mediating rare kaon decay,
GeV. The mixing times are predicted in the range sec.Comment: 36 pages Latex, 9 figures and 5 table
Quantum electrodynamics in a whispering-gallery microcavity coated with a polymer nanolayer
Quasi-transverse-electric and -transverse-magnetic fundamental whispering
gallery modes in a polymer-coated silica microtoroid are theoretically
investigated and demonstrated to possess very high-quality factors. The
existence of a nanometer-thickness layer not only evidently reduces the cavity
mode volume but also draws the maximal electric field's position of the mode to
the outside of the silica toroid, where single quantum dots or nanocrystals are
located. Both effects result in a strongly enhanced coherent interaction
between a single dipole (for example, a single defect center in a diamond
crystal) and the quantized cavity mode. Since the coated microtoroid is highly
feasible and robust in experiments, it may offer an excellent platform to study
strong-coupling cavity quantum electrodynamics, quantum information, and
quantum computation
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