Feynman-Jackson integrals

We introduce perturbative Feynman integrals in the context of q-calculus generalizing the Gaussian q-integrals introduced by Diaz and Teruel. We provide analytic as well as combinatorial interpretations for the Feynman-Jackson integrals.Comment: Final versio

Coherent phenomena in mesoscopic systems

A mesoscopic system of cylindrical geometry made of a metal or a semiconductor is shown to exhibit features of a quantum coherent state. It is shown that magnetostatic interaction can play an important role in mesoscopic systems leading to an ordered ground state. The temperature $T^{*}$ below the system exhibits long-range order is determined. The self-consistent mean field approximation of the magnetostatic interaction is performed giving the effective Hamiltonian from which the self-sustaining currents can be obtained. The relation of quantum coherent state in mesoscopic cylinders to other coherent systems like superconductors is discussed.Comment: REVTeX, 4 figures, in print in Supercond. Sci. Techno

Identifying the Higgs Boson in Electron--Photon Collisions

We analyze the production and detection of the Higgs boson in the next generation of linear $e^+e^-$ colliders operating in the $e\gamma$ mode. In particular, we study the production mechanism $e + \gamma \rightarrow e \gamma \gamma \rightarrow e + H$, where one photon is generated via the laser backscattering mechanism, while the other is radiated via the usual bremsstrahlung process. We show that this is the most important mechanism for Higgs boson production in a $500$ GeV $e\gamma$ collider for M_H\raisebox{-.4ex}{\rlap{\sim}} \raisebox{.4ex}{>}140 GeV. We also study the signals and backgrounds for detection of the Higgs in the different decay channels, $b \bar b$, $W^+W^-$, and $ZZ$, and suggest kinematical cuts to improve the signature of an intermediate mass Higgs boson.Comment: (REVTEX 2.0, 12 pages and 9 figures available upon request, Preprint MAD/PH/753

Solar Flux Emergence Simulations

We simulate the rise through the upper convection zone and emergence through the solar surface of initially uniform, untwisted, horizontal magnetic flux with the same entropy as the non-magnetic plasma that is advected into a domain 48 Mm wide from from 20 Mm deep. The magnetic field is advected upward by the diverging upflows and pulled down in the downdrafts, which produces a hierarchy of loop like structures of increasingly smaller scale as the surface is approached. There are significant differences between the behavior of fields of 10 kG and 20 or 40 kG strength at 20 Mm depth. The 10 kG fields have little effect on the convective flows and show little magnetic buoyancy effects, reaching the surface in the typical fluid rise time from 20 Mm depth of 32 hours. 20 and 40 kG fields significantly modify the convective flows, leading to long thin cells of ascending fluid aligned with the magnetic field and their magnetic buoyancy makes them rise to the surface faster than the fluid rise time. The 20 kG field produces a large scale magnetic loop that as it emerges through the surface leads to the formation of a bipolar pore-like structure.Comment: Solar Physics (in press), 12 pages, 13 figur

Fermi LAT Gamma-ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) gamma-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of gamma-ray onsets beginning ~2 days after their first optical peaks. Significant gamma-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer duration emission compared to previous gamma-ray detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the timespans of the observed gamma rays. The gamma-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons to other novae detected by the LAT are discussed.Comment: 13 pages, 6 figures, 4 tables, ApJ accepte

Persistent currents in diffusive metallic cavities: Large values and anomalous scaling with disorder

The effect of disorder on confined metallic cavities with an Aharonov-Bohm flux line is addressed. We find that, even deep in the diffusive regime, large values of persistent currents may arise for a wide variety of geometries. We present numerical results supporting an anomalous scaling law of the average typical current $$ with the strength of disorder $w$, $\sim w^{- \gamma}$ with $\gamma < 2$. This is contrasted with previously reported results obtained for cylindrical samples where a scaling $\sim w^{-2}$ has been found. Possible links to, up to date, unexplained experimental data are finally discussed.Comment: 5 pages, 4 figure

The Lower Critical Dimension of the XY Spin Glass

We investigate the XY spin-glass model in two and three dimensions using the domain-wall renormalization-group method. The results for systems of linear sizes up to L=12 (2D) and L=8 (3D) strongly suggest that the lower critical dimension for spin-glass ordering may be $d_{c}\approx 3$ rather than four as is commonly believed. Our 3D data favor the scenario of a low but finite spin-glass ordering temperature below the chiral transition but they are also compatible with the system being at or slightly below its lower critical dimension.Comment: 4 pages, 3 ps figures. Typos have been corrected, one reference has been added and the concluding paragraph has been expanded. To appear in Phys. Rev. Let

Quartic Anomalous Couplings in γγ\gamma\gamma Colliders

We study the constraints on the vertices $W^+W^- Z\gamma$, $W^+W^-\gamma\gamma$, and $ZZ\gamma\gamma$ that can be obtained from triple-gauge-boson production at the next generation of linear $e^+e^-$ colliders operating in the $\gamma\gamma$ mode. We analyze the processes $\gamma\gamma \to W^+W^-V$ ($V=Z$, or $\gamma$) and show that these reactions increase the potential of $e^+e^-$ machines to search for anomalous four-gauge-boson interactions.Comment: 15 pages, Latex file using ReVteX, 4 uufiled figures include

On-Shell Recursion Relations for Generic Theories

We show that on-shell recursion relations hold for tree amplitudes in generic two derivative theories of multiple particle species and diverse spins. For example, in a gauge theory coupled to scalars and fermions, any amplitude with at least one gluon obeys a recursion relation. In (super)gravity coupled to scalars and fermions, the same holds for any amplitude with at least one graviton. This result pertains to a broad class of theories, including QCD, N=4 SYM, and N=8 supergravity.Comment: 19 pages, 3 figure