7,152 research outputs found
A Burgess-like subconvex bound for twisted L-functions
Let g be a cuspidal newform (holomorphic or Maass) of arbitrary level and nebentypus, X a primitive character of conductor q, and s a point on the critical line Rs = 1/2. It is proved that
L(g circle times chi, s) 0
is arbitrary and theta = 7/64 is the current known approximation towards the RamannJan-Petersson conjecture (which would allow theta = 0); moreover, the dependence on s and all the parameters of g is polynomial. This result is an analog of Burgess' classical subconvex bound for Dirichlet L-functions. In Appendix 2 the above result is combined with a theorem of Waldspurger and the adelic calculations of Baruch-Mao to yield an improved uniform upper bound for the Fourier coefficients of holomorphic half-integral weight cusp forms
Periodic ripples in suspended graphene
We study the mechanism of wrinkling of suspended graphene, by means of
atomistic simulations. We argue that the structural instability under edge
compression is the essential physical reason for the formation of periodic
ripples in graphene. The ripple wavelength and out-of-plane amplitude are found
to obey 1/4-power scaling laws with respect to edge compression. Our results
also show that parallel displacement of the clamped boundaries can induce
periodic ripples, with oscillation amplitude roughly proportional to the 1/4
power of edge displacement. The results are fundamental to graphene's
applications in electronics.Comment: 5 Figure
On the Localized superluminal Solutions to the Maxwell Equations
In the first part of this article the various experimental sectors of physics
in which Superluminal motions seem to appear are briefly mentioned, after a
sketchy theoretical introduction. In particular, a panoramic view is presented
of the experiments with evanescent waves (and/or tunneling photons), and with
the "Localized superluminal Solutions" (SLS) to the wave equation, like the
so-called X-shaped waves. In the second part of this paper we present a series
of new SLSs to the Maxwell equations, suitable for arbitrary frequencies and
arbitrary bandwidths: some of them being endowed with finite total energy.
Among the others, we set forth an infinite family of generalizations of the
classic X-shaped wave; and show how to deal with the case of a dispersive
medium. Results of this kind may find application in other fields in which an
essential role is played by a wave-equation (like acoustics, seismology,
geophysics, gravitation, elementary particle physics, etc.). This e-print, in
large part a review, was prepared for the special issue on "Nontraditional
Forms of Light" of the IEEE JSTQE (2003); and a preliminary version of it
appeared as Report NSF-ITP-02-93 (KITP, UCSB; 2002). Further material can be
found in the recent e-prints arXiv:0708.1655v2 [physics.gen-ph] and
arXiv:0708.1209v1 [physics.gen-ph]. The case of the very interesting (and more
orthodox, in a sense) subluminal Localized Waves, solutions to the wave
equations, will be dealt with in a coming paper. [Keywords: Wave equation; Wave
propagation; Localized solutions to Maxwell equations; Superluminal waves;
Bessel beams; Limited-dispersion beams; Electromagnetic wavelets; X-shaped
waves; Finite-energy beams; Optics; Electromagnetism; Microwaves; Special
relativity]Comment: LaTeX paper of 37 pages, with 20 Figures in jpg [to be processed by
PDFlatex
Neutrino Mass Implications for Muon Decay Parameters
We use the scale of neutrino mass to derive model-independent naturalness
constraints on possible contributions to muon decay Michel parameters from new
physics above the electroweak symmetry-breaking scale. Focusing on Dirac
neutrinos, we obtain a complete basis of effective dimension four and dimension
six operators that are invariant under the gauge symmetry of the Standard Model
and that contribute to both muon decay and neutrino mass. We show that -- in
the absence of fine tuning -- the most stringent bounds on chirality-changing
operators relevant to muon decay arise from one-loop contributions to neutrino
mass. The bounds we obtain on their contributions to the Michel parameters are
four or more orders of magnitude stronger than bounds previously obtained in
the literature. We also show that there exist chirality-changing operators that
contribute to muon decay but whose flavor structure allows them to evade
neutrino mass naturalness bounds. We discuss the implications of our analysis
for the interpretation of muon decay experiments.Comment: 19 pages, 4 figure
Differentiated Bayesian Conjoint Choice Designs
Previous conjoint choice design construction procedures have produced a single design that is administered to all subjects. This paper proposes to construct a limited set of different designs. The designs are constructed in a Bayesian fashion, taking into account prior uncertainty about the parameter values. A computational procedure is developed that enables fast and easy implementation in practice. Even though the number of such different designs in the optimal set is small, it is demonstrated through a Monte Carlo study that substantial gains in efficiency are achieved over aggregate designs
Generation of the electrostatic field in the pulsar magnetosphere plasma
The behaviour of a relativistic electron-positron plasma in the pulsar
magnetosphere is investigated. The equation of the motion of the magnetospheric
plasma is discussed, from which it follows that, if the plasma particle radial
velocity (where c is the speed of light), the centrifugal
acceleration changes its sign and the particle braking begins. The stability of
the magnetospheric plasma with respect to the radially oriented potential
perturbations is discussed and the possibility of the electrostatic field
generation in this plasma along the pulsar magnetic field lines is shown.Comment: Plain LaTe
Multi-site observations of Delta Scuti stars 7 Aql and 8 Aql (a new Delta Scuti variable): The twelfth STEPHI campaign in 2003
We present an analysis of the pulsation behaviour of the Delta Scuti stars 7
Aql (HD 174532) and 8 Aql (HD 174589) -- a new variable star -- observed in the
framework of STEPHI XII campaign during 2003 June--July. 183 hours of high
precision photometry were acquired by using four-channel photometers at three
sites on three continents during 21 days. The light curves and amplitude
spectra were obtained following a classical scheme of multi-channel photometry.
Observations in different filters were also obtained and analyzed. Six and
three frequencies have been unambiguously detected above a 99% confidence level
in the range 0.090 mHz--0.300 mHz and 0.100 mHz-- 0.145 mHz in 7 Aql and 8 Aql
respectively. A comparison of observed and theoretical frequencies shows that 7
Aql and 8 Aql may oscillate with p modes of low radial orders, typical among
Delta Scuti stars. In terms of radial oscillations the range of 8 Aql goes from
n=1 to n=3 while for 7 Aql the range spans from n=4 to n=7. Non-radial
oscillations have to be present in both stars as well. The expected range of
excited modes according to a non adiabatic analysis goes from n=1 to n=6 in
both stars.Comment: 8 pages, 7 fugures, 5 tables, accepted for publication in
Astronomical Journa
Miniature photonic-crystal hydrophone optimized for ocean acoustics
This work reports on an optical hydrophone that is insensitive to hydrostatic
pressure, yet capable of measuring acoustic pressures as low as the background
noise in the ocean in a frequency range of 1 Hz to 100 kHz. The miniature
hydrophone consists of a Fabry-Perot interferometer made of a photonic-crystal
reflector interrogated with a single-mode fiber, and is compatible with
existing fiber-optic technologies. Three sensors with different acoustic power
ranges placed within a sub-wavelength sized hydrophone head allow a high
dynamic range in the excess of 160 dB with a low harmonic distortion of better
than -30 dB. A method for suppressing cross coupling between sensors in the
same hydrophone head is also proposed. A prototype was fabricated, assembled,
and tested. The sensitivity was measured from 100 Hz to 100 kHz, demonstrating
a minimum detectable pressure down to 12 {\mu}Pa (1-Hz noise bandwidth), a
flatband wider than 10 kHz, and very low distortion
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