3,094 research outputs found
Topological Electropoles in 4+1 Dimensional EYMCS Theory
A class of explicit exact solutions of Einstein Yang Mills Chern Simons
(EYMCS) theory corresponding to topological solitons carrying non-Abelian
topological electric charge is obtained. This verifies a conjecture made in
Ref.[1,2] regarding the stabilization of the corresponding charged
configurations in the theory without gravity .Comment: 11 pages ,Plain TeX,IOPB/BBSR/94-11. Minor typos in eqns(4),(7),
(13a),(13b),(21) correcte
Topological Soliton Multiplets in 4+1 Dimensional YMCS Theory
We generalize our results on charged topological solitons (CTS) in
dimensional Yang-Mills-Chern-Simons (YMCS) theory to . The
multiplet structure of two classes of solitons associated with the
maximal embeddings and and the vital role of the multiplet of
topological currents is clarified. In the case of the first embedding one
obtains a plet of CTS. In the second, for , one obtains
neutral solitons which, though (classically) spinless, have magnetic moments.
For , after modding out the above mentioned non-particulate feature,
one obtains plets of CTS.Comment: (minor semantic changes), 21
Proton decay matrix elements with domain-wall fermions
Hadronic matrix elements of operators relevant to nucleon decay in grand
unified theories are calculated numerically using lattice QCD. In this context,
the domain-wall fermion formulation, combined with non-perturbative
renormalization, is used for the first time. These techniques bring reduction
of a large fraction of the systematic error from the finite lattice spacing.
Our main effort is devoted to a calculation performed in the quenched
approximation, where the direct calculation of the nucleon to pseudoscalar
matrix elements, as well as the indirect estimate of them from the nucleon to
vacuum matrix elements, are performed. First results, using two flavors of
dynamical domain-wall quarks for the nucleon to vacuum matrix elements are also
presented to address the systematic error of quenching, which appears to be
small compared to the other errors. Our results suggest that the representative
value for the low energy constants from the nucleon to vacuum matrix elements
are given as |alpha| simeq |beta| simeq 0.01 GeV^3. For a more reliable
estimate of the physical low energy matrix elements, it is better to use the
relevant form factors calculated in the direct method. The direct method tends
to give smaller value of the form factors, compared to the indirect one, thus
enhancing the proton life-time; indeed for the pi^0 final state the difference
between the two methods is quite appreciable.Comment: 56 pages, 17 figures, a comment and two references added in the
introduction, typo corrected in Eq.1
A new window on Strange Quark Matter as the ground state of strongly interacting matter
If strange quark matter is the true ground state of matter, it must have
lower energy than nuclear matter. Simultaneously, two-flavour quark matter must
have higher energy than nuclear matter, for otherwise the latter would convert
to the former. We show, using an effective chiral lagrangian, that the
existence of a new lower energy ground state for two-flavour quark matter, the
pion condensate, shrinks the window for strange quark matter to be the ground
state of matter and sets new limits on the current strange quark mass
A Study of Morris-Thorne Wormhole in Einstein-Cartan Theory
This paper focuses on the Einstein-Cartan theory, an extension of general
relativity that incorporates a torsion tensor into spacetime. The differential
form technique is employed to analyze the Einstein-Cartan theory, which
replaces tensors with tetrads. A tetrad formalism, specifically the
Newmann-Penrose-Jogia-Griffiths formalism, is used to study the field
equations. The energy-momentum tensor is also determined, considering a
Weyssenhoff fluid with anisotropic matter. The spin density is derived in terms
of the red-shift function. We also examine the energy conditions at the throat
of a Morris-Thorne wormhole. The results shed light on the properties of
wormholes in the context of the Einstein-Cartan theory, including the energy
conditions at the throat.Comment: 20 pages, 3 figures, 1 table. Preparing for submission to the
International Journal of Geometric Methods in Modern Physic
Anomalous Thermoelectric power of over-doped Bi2Sr2CaCu2O8 superconductor
Temperature dependence of thermoelectric power S(T) of three differently
processed Bi2Sr2CaCu2O8 (Bi2212) samples, viz. as-processed melt quenched
(Bi2212-MQ), 6000C N2-annealed (Bi2212-N2) and 6000C O2-annealed (Bi2212-O2) is
reported here. All the samples possess single-phase character and their
superconducting transition temperatures (TcR=0) are 85 K, 90 K and 72 K
respectively for Bi2212-MQ, Bi2212-N2 and Bi2212-O2. While Bi2212-MQ and
Bi2212-N2 samples are in near optimum doping regime, Bi2212-O2 is an over-doped
sample. TcS=0 values obtained through S(T) data are also in line with those
deduced from the temperature dependence of resistance and DC magnetization.
Interestingly, S(T) behaviour of the optimally-doped Bi2212-MQ and Bi2212-N2
samples is seen to be positive in whole temperature range, it is found negative
for the over-doped Bi2212-O2 sample above TcS=0. These results have been seen
in the light of the recent band structure calculations and the ensuing split
Fermi surface as determined by angle-resolved photoelectron spectroscopy
(ARPES).Comment: 11 Pages Text + Figs: comments welcome ([email protected]
Proton lifetime bounds from chirally symmetric lattice QCD
We present results for the matrix elements relevant for proton decay in Grand
Unified Theories (GUTs). The calculation is performed at a fixed lattice
spacing a^{-1}=1.73(3) GeV using 2+1 flavors of domain wall fermions on
lattices of size 16^3\times32 and 24^3\times64 with a fifth dimension of length
16. We use the indirect method which relies on an effective field theory
description of proton decay, where we need to estimate the low energy
constants, \alpha = -0.0112(25) GeV^3 and \beta = 0.0120(26) GeV^3. We relate
these low energy constants to the proton decay matrix elements using leading
order chiral perturbation theory. These can then be combined with experimental
bounds on the proton lifetime to bound parameters of individual GUTs.Comment: 17 pages, 9 Figure
Correlation Functions of Hadron Currents in the QCD Vacuum Calculated in Lattice QCD
Point-to-point vacuum correlation functions for spatially separated hadron
currents are calculated in quenched lattice QCD on a lattice
with . The lattice data are analyzed in terms of dispersion
relations, which enable us to extract physical information from small distances
where asymptotic freedom is apparent to large distances where the hadronic
resonances dominate. In the pseudoscalar, vector, and axial vector channels
where experimental data or phenomenological information are available,
semi-quantitative agreement is obtained. In the nucleon and delta channels,
where no experimental data exist, our lattice data complement experiments.
Comparison with approximations based on sum rules and interacting instantons
are made, and technical details of the lattice calculation are described.Comment: 31 pages in REVTeX (with 10 figures to be added using figures
command), MIT CTP #214
Lattice Calculation of Point-to-Point Hadron Current Correlation
Point-to-point correlation functions of hadron currents in the QCD vacuum are
calculated on a lattice and analyzed using dispersion relations, providing
physical information down to small spatial separations. Qualitative agreement
with phenomenological results is obtained in channels for which experimental
data are available, and these correlation functions are shown to be useful in
exploring approximations based on sum rules and interacting instantons.Comment: 11 page
Does fix the Electromagnetic Form Factor at ?
We show that the decay is a reliable
source of information for the electromagnetic form factor of the pion at
by using general arguments to estimate, or
rather, put upper bounds on, the background processes that could spoil this
extraction. We briefly comment on the significance of the resulting
.Comment: 10 pages revtex manuscript, one figure--not included, U. of MD PP
#94-00
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