6,781 research outputs found
Importance of Sea Contribution to Nucleons
We studied the statistical model of nucleons consisting of sea having various
quark-gluon Fock states in addition to valence quarks. Using statistical
consideration and taking 86% of the total Fock states contributing to the low
energy properties of nucleon, we aim to find the contributions to these
properties coming from the scalar, vector and tensor sea. We checked its
validity against the assumption where the contributions from scalar and tensor
sea have been suppressed and justified to be unimportant. We took the
approximation that sea is getting a zero contribution from H_0 G_\bar10 and H_1
G_\bar10 in three gluon states. Under above considerations, the calculated
magnetic moment, spin distribution and weak decay coupling constant ratio for
proton and neutron states have been tabulated. We hereby confirm that the
suppression of the scalar and tensor sea leads to modification in the
parameters of the nucleons showing deviation from the experimental data.Comment: 13 pages, 5 figures, To be published in NP
On sets of irreducible polynomials closed by composition
Let  be a set of monic degree  polynomials over a finite field
and let  be the compositional semigroup generated by . In this
paper we establish a necessary and sufficient condition for  to be
consisting entirely of irreducible polynomials. The condition we deduce depends
on the finite data encoded in a certain graph uniquely determined by the
generating set . Using this machinery we are able both to show
examples of semigroups of irreducible polynomials generated by two degree 
polynomials and to give some non-existence results for some of these sets in
infinitely many prime fields satisfying certain arithmetic conditions
D-Terms, Unification, and the Higgs Mass
We study gauge extensions of the MSSM that contain non-decoupling D-terms,
which contribute to the Higgs boson mass. These models naturally maintain gauge
coupling unification and raise the Higgs mass without fine-tuning. Unification
constrains the structure of the gauge extensions, limiting the Higgs mass in
these models to roughly less than 150 GeV. The D-terms contribute to the Higgs
mass only if the extended gauge symmetry is broken at energies of a few TeV,
leading to new heavy gauge bosons in this mass range.Comment: 30+1 pages, 7 figure
Anomaly-Free Sets of Fermions
We present new techniques for finding anomaly-free sets of fermions. Although
the anomaly cancellation conditions typically include cubic equations with
integer variables that cannot be solved in general, we prove by construction
that any chiral set of fermions can be embedded in a larger set of fermions
which is chiral and anomaly-free. Applying these techniques to extensions of
the Standard Model, we find anomaly-free models that have arbitrary quark and
lepton charges under an additional U(1) gauge group.Comment: 21 (+1) page
Role of Phenolics in Anti-Atherosclerotic Property of Thuja occidentalis Linn.
The present study was carried out to evaluate the Lipid peroxidation activity and related hypolipidaemic activity of an (EFTO) ethanol fraction of extract of aerial part of Thuja occidentalis Linn. (Cupressaceae). Lipid peroxidation activity was carried out to evaluate the antioxidant potential, and hypolipidaemic activity on cholesterol fed rats. The antioxidant activity of ethanol fraction was increased in a concentration dependent manner. About 100, 150, 200, 250 & 300 μg EFTO (ethanol fraction of extract of aerial part of Thuja occidentalis) inhibited the FeSO4 induced lipid peroxidation in a dose dependent manner and showed IC50 value 195.60μg/ml. in hypolipidaemic activity EFTO at the dose of 200 mg and 400mg/kg body weight significantly reduced serum cholesterol (77 and 92%), LDL (53 and 84%), triglycerides (27 and 46%). The increase in HDL to total cholesterol ratio and reduction in atherogenic index in EFTO treated groups strongly supports anti-atherosclerotic property of Thuja occidentalis. The results obtained in this study indicate that EFTO can be a potential source of natural antioxidant and activities related to this
A Determination of the Hubble Constant from Cepheid Distances and a Model of the Local Peculiar Velocity Field
We present a measurement of the Hubble Constant based on Cepheid distances to
27 galaxies within 20 Mpc. We take the Cepheid data from published measurements
by the Hubble Telescope Key Project on the Distance Scale (H0KP). We calibrate
the Cepheid Period-Luminosity (PL) relation with data from over 700 Cepheids in
the LMC obtained by the OGLE collaboration; we assume an LMC distance modulus
of 18.50 mag (d=50.1 kpc). Using this PL calibration we obtain new distances to
the H0KP galaxies. We correct the redshifts of these galaxies for peculiar
velocities using two distinct velocity field models: the phenomenological model
of Tonry et al. and a model based on the IRAS density field and linear
gravitational instability theory. We combine the Cepheid distances with the
corrected redshifts for the 27 galaxies to derive H_0, the Hubble constant. The
results are H_0 = 85 +/- 5 km/s/Mpc (random error) at 95% confidence when the
IRAS model is used, and 92 +/- 5 km/s/Mpc when the phenomenological model is
used. The IRAS model is a better fit to the data and the Hubble constant it
returns is more reliable. Systematic error stems mainly from LMC distance
uncertainty which is not directly addressed by this paper. Our value of H_0 is
significantly larger than that quoted by the H0KP, H_0 = 71 +/- 6 km/s/Mpc.
Cepheid recalibration explains ~30% of this difference, velocity field analysis
accounts for ~70%. We discuss in detail possible reasons for this discrepancy
and future study needed to resolve it.Comment: 33 pages, 8 embedded figures. New table, 5 new references, text
  revision
The New Fat Higgs: Slimmer and More Attractive
In this paper we increase the MSSM tree level higgs mass bound to a value
that is naturally larger than the LEP-II search constraint by adding to the
superpotential a  term, as in the NMSSM, and UV
completing with new strong dynamics {\it before}  becomes
non-perturbative. Unlike other models of this type the higgs fields remain
elementary, alleviating the supersymmetric fine-tuning problem while
maintaining unification in a natural way.Comment: 14 pages and 2 figures. Added references and updated argument about
  constraints from reheating temperatur
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