3,144 research outputs found
Exotic solutions in string theory
Solutions of classical string theory, correspondent to the world sheets,
mapped in Minkowsky space with a fold, are considered. Typical processes for
them are creation of strings from vacuum, their recombination and annihilation.
These solutions violate positiveness of square of mass and Regge condition. In
quantum string theory these solutions correspond to physical states |DDF>+|sp>
with non-zero spurious component.Comment: accepted in Il Nuovo Cimento A for publication in 199
Cooper pairing and finite-size effects in a NJL-type four-fermion model
Starting from a NJL-type model with N fermion species fermion and difermion
condensates and their associated phase structures are considered at nonzero
chemical potential and zero temperature in spaces with nontrivial
topology of the form and . Special
attention is devoted to the generation of the superconducting phase. In
particular, for the cases of antiperiodic and periodic boundary conditions we
have found that the critical curve of the phase transitions between the chiral
symmetry breaking and superconducting phases as well as the corresponding
condensates and particle densities strongly oscillate vs ,
where is the length of the circumference . Moreover, it is shown that
at some finite values of the superconducting phase transition is shifted to
smaller values both of and particle density in comparison with the case
of .Comment: 13 pages, 13 figures; minor changes; new references added; version
accepted to PR
LIGO End-to-End simulation Program
A time-domain simulation program has been developed to provide an accurate description of interferometric gravitational wave detectors. This is being utilized to build a model of LIGO with the aim of aiding in the shakedown and integration of the interferometer subsystems, and ultimately the optimization of detector sensitivity
Diffraction dissociation in proton-proton collisions at = 0.9 TeV, 2.76 TeV and 7 TeV with ALICE at the LHC
The relative rates of single- and double- diffractive processes were measured
with the ALICE detector by studying properties of gaps in the pseudorapidity
distribution of particles produced in proton-proton collisions at =
0.9 TeV, 2.76 TeV and 7 TeV. ALICE triggering efficiencies are determined for
various classes of events, using a detector simulation validated with data on
inclusive particle production. Cross-sections are determined using van der Meer
scans to measure beam properties and obtain a measurement of the luminosity
Coherent method for detection of gravitational wave bursts
We describe a coherent network algorithm for detection and reconstruction of
gravitational wave bursts. The algorithm works for two and more arbitrarily
aligned detectors and can be used for both all-sky and triggered burst
searches. We describe the main components of the algorithm, including the
time-frequency analysis in wavelet domain, construction of the likelihood
time-frequency maps, the identification and selection of burst events.Comment: 11 pages, 3 figures, proceedings of Amaldi conference in Sydney,
Australi
Finite Density Effect in the Gross-Neveu Model in a Weakly Curved Spacetime
The three-dimensional Gross-Neveu model in spacetime is
considered at finite particles number density. We evaluate an effective
potential of the composite scalar field , which is expressed in
terms of a scalar curvature and nonzero chemical potential . We then
derive the critical values of at which the system undergoes the first
order phase transition from the phase with broken chiral invariance to the
symmetric phase.Comment: RevTeX, minor changes, new references are adde
Chiral phase transitions in strong chromomagnetic fields at finite temperature and dimensional reduction
Dynamical fermion mass generation in external chromomagnetic fields is
considered at non--zero temperature. The general features of dynamical chiral
symmetry breaking () are investigated for several field
configurations in relation to their symmetry properties and the form of the
quark spectrum. According to the fields, there arises dimensional reduction by
one or two units. In all cases there exists even at weak quark
attraction, confirming the idea about the dimensional insensitivity of this
mechanism in a chromomagnetic field.Comment: LATEX file, 12 pages, no figure
A new look at the modified Coulomb potential in a strong magnetic field
The static Coulomb potential of Quantum Electrodynamics (QED) is calculated
in the presence of a strong magnetic field in the lowest Landau level (LLL)
approximation using two different methods. First, the vacuum expectation value
of the corresponding Wilson loop is calculated perturbatively in two different
regimes of dynamical mass , {\it i.e.}, and , where
is the longitudinal components of the momentum relative to
the external magnetic field . The result is then compared with the static
potential arising from Born approximation. Both results coincide. Although the
arising potentials show different behavior in the aforementioned regimes, a
novel dependence on the angle between the particle-antiparticle's axis
and the direction of the magnetic field is observed. In the regime
, for strong enough magnetic
field and depending on the angle , a qualitative change occurs in the
Coulomb-like potential; Whereas for the potential is repulsive,
it exhibits a minimum for angles .Comment: V1: 26 pages, 8 figures, latex format, V2: Accepted for publication
in PRD (2007
A tapering window for time-domain templates and simulated signals in the detection of gravitational waves from coalescing compact binaries
Inspiral signals from binary black holes, in particular those with masses in
the range 10M_\odot \lsim M \lsim 1000 M_\odot, may last for only a few
cycles within a detector's most sensitive frequency band. The spectrum of a
square-windowed time-domain signal could contain unwanted power that can cause
problems in gravitational wave data analysis, particularly when the waveforms
are of short duration. There may be leakage of power into frequency bins where
no such power is expected, causing an excess of false alarms. We present a
method of tapering the time-domain waveforms that significantly reduces
unwanted leakage of power, leading to a spectrum that agrees very well with
that of a long duration signal. Our tapered window also decreases the false
alarms caused by instrumental and environmental transients that are picked up
by templates with spurious signal power. The suppression of background is an
important goal in noise-dominated searches and can lead to an improvement in
the detection efficiency of the search algorithms
A High-Density SSR Linkage Map of Red Clover and Its Transferability to Other Legumes
A high-density linkage map of red clover was constructed based on SSR and RFLP markers. In order to construct a linkage map with user (breeder) friendly markers; i.e. informative and easy detection, two policies were adopted for marker development. One was that the markers should be derived from cDNA or gene-rich regions, and the other was that the SSR markers should be detected polymorphisms on agarose gels. We also discuss the transferability of the markers on the map to other red clover germplasm and legumes. Such highly transferable markers could be used to screen anchor markers for both on a consensus map of red clover and other legume species
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