6,971 research outputs found
Geometric Mean Neutrino Mass Relation
Present experimental data from neutrino oscillations have provided much
information about the neutrino mixing angles. Since neutrino oscillations only
determine the mass squared differences , the
absolute values for neutrino masses can not be determined using data just
from oscillations. In this work we study implications on neutrino masses from a
geometric mean mass relation which enables one to
determined the absolute masses of the neutrinos. We find that the central
values of the three neutrino masses and their errors to be , , and . Implications for cosmological observation, beta decay and
neutrinoless double beta decays are discussed.Comment: 7 pages. Talk given at COSPA06. A reference adde
A steepest descent calculation of RNA pseudoknots
We enumerate possible topologies of pseudoknots in single-stranded RNA
molecules. We use a steepest-descent approximation in the large N matrix field
theory, and a Feynman diagram formalism to describe the resulting pseudoknot
structure
Charge breaking bounds in the Zee model
We study the possibility that charge breaking minima occur in the Zee model.
We reach very different conclusions from those attained in simpler, two Higgs
doublet models, and the reason for this is traced back to the existence of
cubic terms in the potential. A scan of the Zee model's parameter space shows
that CB is restricted to a narrow region of values of the parameters
Enumeration of RNA structures by Matrix Models
We enumerate the number of RNA contact structures according to their genus,
i.e. the topological character of their pseudoknots. By using a recently
proposed matrix model formulation for the RNA folding problem, we obtain exact
results for the simple case of an RNA molecule with an infinitely flexible
backbone, in which any arbitrary pair of bases is allowed. We analyze the
distribution of the genus of pseudoknots as a function of the total number of
nucleotides along the phosphate-sugar backbone.Comment: RevTeX, 4 pages, 2 figure
Anomalies at finite density and chiral fermions
Using perturbation theory in the Euclidean (imaginary time) formalism as well
as the non-perturbative Fujikawa method, we verify that the chiral anomaly
equation remains unaffected in the presence of nonzero chemical potential,
. We extend our considerations to fermions with exact chiral symmetry on
the lattice and discuss the consequences for the recent Bloch-Wettig proposal
for the Dirac operator at finite chemical potential. We propose a new simpler
method of incorporating and compare it with the Bloch-Wettig idea.Comment: 12 pages, 3 figures,some typos corrected, a better proof for the \mu
independence of anomaly is given in section IIB, v4: the published versio
Propagation of Vortex Electron Wave Functions in a Magnetic Field
The physics of coherent beams of photons carrying axial orbital angular
momentum (OAM) is well understood and such beams, sometimes known as vortex
beams, have found applications in optics and microscopy. Recently electron
beams carrying very large values of axial OAM have been generated. In the
absence of coupling to an external electromagnetic field the propagation of
such vortex electron beams is virtually identical mathematically to that of
vortex photon beams propagating in a medium with a homogeneous index of
refraction. But when coupled to an external electromagnetic field the
propagation of vortex electron beams is distinctly different from photons. Here
we use the exact path integral solution to Schrodingers equation to examine the
time evolution of an electron wave function carrying axial OAM. Interestingly
we find that the nonzero OAM wave function can be obtained from the zero OAM
wave function, in the case considered here, simply by multipling it by an
appropriate time and position dependent prefactor. Hence adding OAM and
propagating can in this case be replaced by first propagating then adding OAM.
Also, the results shown provide an explicit illustration of the fact that the
gyromagnetic ratio for OAM is unity. We also propose a novel version of the
Bohm-Aharonov effect using vortex electron beams.Comment: 14 pages, 2 figures, submitted to Phys Rev
Predictions from the Fritzsch-Type Lepton Mass Matrices
We revisit the Fritzsch-type lepton mass matrix models confronted with new
experiments for neutrino mixings. It is shown that the model is viable and
leads to a rather narrow range of free parameters. Using empirical mixing
information between and , and between and
, it is predicted that the mixing angle between and
is in the range , consistent with the CHOOZ experiment and
the lightest neutrino mass is eV. The range of the
effective mass measured in double beta decay is eV.Comment: Latex file with 13 pages, 6 eps file
Towards Resolution of Hierarchy Problems in a Cosmological Context
A cosmological scenario is proposed, which simultaneously solves the mass
hierarchy and the small dark energy problem. In the present scenario an
effective gravity mass scale (inverse of the Newton's constant) increases
during the inflationary period. The small cosmological constant or the dark
energy density in the present universe is dynamically realized by introducing
two, approximately O(2) symmetric dilatons, taking the fundamental mass scale
at TeV.Comment: 12 pages, no figur
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