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 bq0−bq0barb_q^0-b_q^0 bar 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, $B_s^0-B_s^0 bar$ and $B_d^0-B_d^0 bar$ mass differences are considered taking the effect of both Z-and Z' -mediated flavour-changing neutral currents in the $B_q^0-B_q^0 bar$ 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 ${\mathcal{F}}$-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