14,894 research outputs found
Trident pair production in strong laser pulses
We calculate the trident pair production amplitude in a strong laser
background. We allow for finite pulse duration, while still treating the laser
fields nonperturbatively in strong-field QED. Our approach reveals explicitly
the individual contributions of the one-step and two-step processes. We also
expose the role gauge invariance plays in the amplitudes and discuss the
relation between our results and the optical theorem.Comment: 4 pages, 1 .eps figure. Version 2: reference added, published versio
The Prediction of Mass of Z'-Boson from Mixing
B_q^0-B_^0 bar mixing offers a profound probe into the effects of new
physics beyond the Standard Model. In this paper, and
mass differences are considered taking the effect of both
Z-and Z' -mediated flavour-changing neutral currents in the
mixing (q = d, s). Our estimated mass of Z' boson is accessible at the
experiments LHC and B-factories in near future.Comment: 11 pages, 02 Figure
Searches for continuous gravitational waves from nine young supernova remnants
We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3–25.3 days using the matched-filtering -statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10?25 on intrinsic strain, 2 × 10?7 on fiducial ellipticity, and 4 × 10?5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes
Quantum advantage by relational queries about physically realizable equivalence classes
Relational quantum queries are sometimes capable to effectively decide
between collections of mutually exclusive elementary cases without completely
resolving and determining those individual instances. Thereby the set of
mutually exclusive elementary cases is effectively partitioned into equivalence
classes pertinent to the respective query. In the second part of the paper, we
review recent progress in theoretical certifications (relative to the
assumptions made) of quantum value indeterminacy as a means to build quantum
oracles for randomness.Comment: 8 Pages, one figure, invited contribution to TopHPC2019, Tehran,
Iran, April 22-25, 201
Complementarity and Chiral Fermions in SU(2) gauge Theories
Complementarity - the absence of a phase boundary separating the Higgs and
confinement phases of a gauge theory - can be violated by the addition of
chiral fermions. We utilize chiral symmetry violating fermion correlators such
as \langle \bps \psi \rangle as order parameters to investigate this issue.
Using inequalities similar to those of Vafa-Witten and Weingarten, we show that
SU(2) gauge theories with Higgs and fermion fields in the fundamental
representation exhibit chiral symmetry breaking in the confined phase and
therefore do {\it not} lead to massless composite fermions. We discuss the
implications for the Abbott-Farhi strongly interacting standard model.Comment: 10 pages, HUTP-92-A047, 2 figures not include
Search algorithm for a gravitational wave signal in association with Gamma Ray Burst GRB030329 using the LIGO detectors
One of the brightest Gamma Ray Burst ever recorded, GRB030329, occurred
during the second science run of the LIGO detectors. At that time, both
interferometers at the Hanford, WA LIGO site were in lock and acquiring data.
The data collected from the two Hanford detectors was analyzed for the presence
of a gravitational wave signal associated with this GRB. This paper presents a
detailed description of the search algorithm implemented in the current
analysis.Comment: To appear in the Proceedings of 8th Gravitational Wave Data Analysis
Workshop (Milwaukee, WI) (Class. Quantum Grav.
Breaking stress of neutron star crust
The breaking stress (the maximum of the stress-strain curve) of neutron star
crust is important for neutron star physics including pulsar glitches, emission
of gravitational waves from static mountains, and flares from star quakes. We
perform many molecular dynamic simulations of the breaking stress at different
coupling parameters (inverse temperatures) and strain rates. We describe our
results with the Zhurkov model of strength. We apply this model to estimate the
breaking stress for timescales ~1 s - 1 year, which are most important for
applications, but much longer than can be directly simulated. At these
timescales the breaking stress depends strongly on the temperature. For
coupling parameter <200, matter breaks at very small stress, if it is applied
for a few years. This viscoelastic creep can limit the lifetime of mountains on
neutron stars. We also suggest an alternative model of timescale-independent
breaking stress, which can be used to estimate an upper limit on the breaking
stress.Comment: 5 pages, 2 figures. Accepted for publication in MNRAS Letter
A novel experimental technique and its application to study the effects of particle density and flow submergence on bed particle saltation
This research was sponsored by EPSRC grant EP/G056404/1 which is greatly appreciated.Peer reviewedPublisher PD
Prospects for joint radio telescope and gravitational wave searches for astrophysical transients
The radio skies remain mostly unobserved when it comes to transient
phenomena. The direct detection of gravitational waves will mark a major
milestone of modern astronomy, as an entirely new window will open on the
universe. Two apparently independent phenomena can be brought together in a
coincident effort that has the potential to boost both searches. In this paper
we will outline the scientific case that stands behind these future joint
observations and will describe the methods that might be used to conduct the
searches and analyze the data. The targeted sources are binary systems of
compact objects, known to be strong candidate sources for gravitational waves.
Detection of transients coincident in these two channels would be a significant
smoking gun for first direct detection of gravitational waves, and would open
up a new field for characterization of astrophysical transients involving
massive compact objects.Comment: 12 pages, Amaldi 8 Conference (New York, 2009) proceedings pape
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