451 research outputs found
Multiple addition theorem for discrete and continuous nonlinear problems
The addition relation for the Riemann theta functions and for its limits,
which lead to the appearance of exponential functions in soliton type equations
is discussed. The presented form of addition property resolves itself to the
factorization of N-tuple product of the shifted functions and it seems to be
useful for analysis of soliton type continuous and discrete processes in the
N+1 space-time. A close relation with the natural generalization of bi- and
tri-linear operators into multiple linear operators concludes the paper.Comment: 9 page
Divergence-free Nonrenormalizable Models
A natural procedure is introduced to replace the traditional, perturbatively
generated counter terms to yield a formulation of covariant, self-interacting,
nonrenormalizable scalar quantum field theories that has the added virtue of
exhibiting a divergence-free perturbation analysis. To achieve this desirable
goal it is necessary to reexamine the meaning of the free theory about which
such a perturbation takes place.Comment: 22 pages. Version accepted for publication; involves modest addition
to the end of Sec.
Magnetic permeability of near-critical 3d abelian Higgs model and duality
The three-dimensional abelian Higgs model has been argued to be dual to a
scalar field theory with a global U(1) symmetry. We show that this duality,
together with the scaling and universality hypotheses, implies a scaling law
for the magnetic permeablity chi_m near the line of second order phase
transition: chi_m ~ t^nu, where t is the deviation from the critical line and
nu ~ 0.67 is a critical exponent of the O(2) universality class. We also show
that exactly on the critical lines, the dependence of magnetic induction on
external magnetic field is quadratic, with a proportionality coefficient
depending only on the gauge coupling. These predictions provide a way for
testing the duality conjecture on the lattice in the Coulomb phase and at the
phase transion.Comment: 11 pages; updated references and small changes, published versio
Dynamical generalization of a solvable family of two-electron model atoms with general interparticle repulsion
Holas, Howard and March [Phys. Lett. A {\bf 310}, 451 (2003)] have obtained
analytic solutions for ground-state properties of a whole family of
two-electron spin-compensated harmonically confined model atoms whose different
members are characterized by a specific interparticle potential energy
u(). Here, we make a start on the dynamic generalization of the
harmonic external potential, the motivation being the serious criticism
levelled recently against the foundations of time-dependent density-functional
theory (e.g. [J. Schirmer and A. Dreuw, Phys. Rev. A {\bf 75}, 022513 (2007)]).
In this context, we derive a simplified expression for the time-dependent
electron density for arbitrary interparticle interaction, which is fully
determined by an one-dimensional non-interacting Hamiltonian. Moreover, a
closed solution for the momentum space density in the Moshinsky model is
obtained.Comment: 5 pages, submitted to J. Phys.
Is There Really a de Sitter/CFT Duality
In this paper a de Sitter Space version of Black Hole Complementarity is
formulated which states that an observer in de Sitter Space describes the
surrounding space as a sealed finite temperature cavity bounded by a horizon
which allows no loss of information. We then discuss the implications of this
for the existence of boundary correlators in the hypothesized dS/cft
correspondence. We find that dS complementarity precludes the existence of the
appropriate limits. We find that the limits exist only in approximations in
which the entropy of the de Sitter Space is infinite. The reason that the
correlators exist in quantum field theory in the de Sitter Space background is
traced to the fact that horizon entropy is infinite in QFT.Comment: 12 Figures, STIAS Workshop on Quantum Gravit
Cosmology with Hypervelocity Stars
In the standard cosmological model, the merger remnant of the Milky Way and
Andromeda (Milkomeda) will be the only galaxy remaining within our event
horizon once the Universe has aged by another factor of ten, ~10^{11} years
after the Big Bang. After that time, the only extragalactic sources of light in
the observable cosmic volume will be hypervelocity stars being ejected
continuously from Milkomeda. Spectroscopic detection of the velocity-distance
relation or the evolution in the Doppler shifts of these stars will allow a
precise measurement of the vacuum mass density as well as the local matter
distribution. Already in the near future, the next generation of large
telescopes will allow photometric detection of individual stars out to the edge
of the Local Group, and may target the ~10^{5+-1} hypervelocity stars that
originated in it as cosmological tracers.Comment: 4 pages, 2 figures, accepted for publication in the Journal of
Cosmology and Astroparticle Physics (JCAP, 2011
Neutrino masses in the Lepton Number Violating MSSM
We consider the most general supersymmetric model with minimal particle
content and an additional discrete Z_3 symmetry (instead of R-parity), which
allows lepton number violating terms and results in non-zero Majorana neutrino
masses. We investigate whether the currently measured values for lepton masses
and mixing can be reproduced. We set up a framework in which Lagrangian
parameters can be initialised without recourse to assumptions concerning
trilinear or bilinear superpotential terms, CP-conservation or
intergenerational mixing and analyse in detail the one loop corrections to the
neutrino masses. We present scenarios in which the experimental data are
reproduced and show the effect varying lepton number violating couplings has on
the predicted atmospheric and solar mass^2 differences. We find that with
bilinear lepton number violating couplings in the superpotential of the order 1
MeV the atmospheric mass scale can be reproduced. Certain trilinear
superpotential couplings, usually, of the order of the electron Yukawa coupling
can give rise to either atmospheric or solar mass scales and bilinear
supersymmetry breaking terms of the order 0.1 GeV^2 can set the solar mass
scale. Further details of our calculation, Lagrangian, Feynman rules and
relevant generic loop diagrams, are presented in three Appendices.Comment: 48 pages, 7 figures, v2 references added, typos corrected, published
versio
S3 x Z2 model for neutrino mass matrices
We propose a model for lepton mass matrices based on the seesaw mechanism, a
complex scalar gauge singlet and a horizontal symmetry S_3 \times
\mathbbm{Z}_2. In a suitable weak basis, the charged-lepton mass matrix and
the neutrino Dirac mass matrix are diagonal, but the vacuum expectation value
of the scalar gauge singlet renders the Majorana mass matrix of the
right-handed neutrinos non-diagonal, thereby generating lepton mixing. When the
symmetry is not broken in the scalar potential, the effective
light-neutrino Majorana mass matrix enjoys -- interchange symmetry,
thus predicting maximal atmospheric neutrino mixing together with .
A partial and less predictive form of -- interchange symmetry is
obtained when the symmetry is softly broken in the scalar potential.
Enlarging the symmetry group S_3 \times \mathbbm{Z}_2 by an additional
discrete electron-number symmetry \mathbbm{Z}_2^{(e)}, a more predicitive
model is obtained, which is in practice indistinguishable from a previous one
based on the group .Comment: 13 pages, 3 figures, final version for publication in JHE
Is There A String Theory Landscape
We examine recent claims of a large set of flux compactification solutions of
string theory. We conclude that the arguments for AdS solutions are plausible.
The analysis of meta-stable dS solutions inevitably leads to situations where
long distance effective field theory breaks down. We then examine whether these
solutions are likely to lead to a description of the real world. We conclude
that one must invoke a strong version of the anthropic principle. We explain
why it is likely that this leads to a prediction of low energy supersymmetry
breaking, but that many features of anthropically selected flux
compactifications are likely to disagree with experiment.Comment: 39 pages, Latex, ``Terminology surrounding the anthropic principle
revised to conform with accepted usage. More history of the anthropic
principle included. Various references added.
Higgs mediated Double Flavor Violating top decays in Effective Theories
The possibility of detecting double flavor violating top quark transitions at
future colliders is explored in a model-independent manner using the effective
Lagrangian approach through the () decays. A
Yukawa sector that contemplates invariants of up to
dimension six is proposed and used to derive the most general flavor violating
and CP violating and vertices of renormalizable type.
Low-energy data, on high precision measurements, and experimental limits are
used to constraint the and vertices and then used to
predict the branching ratios for the decays. It is found
that this branching ratios may be of the order of , for a
relative light Higgs boson with mass lower than , which could be more
important than those typical values found in theories beyond the standard model
for the rare top quark decays () or . %% LHC experiments, by using a total integrated luminosity of of data, will be able to rule out, at 95% C.L., DFV top quark
decays up to a Higgs mass of 155 GeV/ or discover such a process up to a
Higgs mass of 147 GeV/.Comment: 24 pages, 11 figure
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