5,527 research outputs found
Remarks on twisted noncommutative quantum field theory
We review recent results on twisted noncommutative quantum field theory by
embedding it into a general framework for the quantization of systems with a
twisted symmetry. We discuss commutation relations in this setting and show
that the twisted structure is so rigid that it is hard to derive any
predictions, unless one gives up general principles of quantum theory. It is
also shown that the twisted structure is not responsible for the presence or
absence of UV/IR-mixing, as claimed in the literature.Comment: 13 pages, v2: minor correction
Utility based pricing and hedging of jump diffusion processes with a view to applications
We discuss utility based pricing and hedging of jump diffusion processes with
emphasis on the practical applicability of the framework. We point out two
difficulties that seem to limit this applicability, namely drift dependence and
essential risk aversion independence. We suggest to solve these by a
re-interpretation of the framework. This leads to the notion of an implied
drift. We also present a heuristic derivation of the marginal indifference
price and the marginal optimal hedge that might be useful in numerical
computations.Comment: 23 pages, v2: publishe
A Robust Measure of Tidal Circularization in Coeval Binary Populations: The solar-type spectroscopic Binary Population in The Open Cluster M35
We present a new homogeneous sample of 32 spectroscopic binary orbits in the
young (~ 150 Myr) main-sequence open cluster M35. The distribution of orbital
eccentricity vs. orbital period (e-log(P)) displays a distinct transition from
eccentric to circular orbits at an orbital period of ~ 10 days. The transition
is due to tidal circularization of the closest binaries. The population of
binary orbits in M35 provide a significantly improved constraint on the rate of
tidal circularization at an age of 150 Myr. We propose a new and more robust
diagnostic of the degree of tidal circularization in a binary population based
on a functional fit to the e-log(P) distribution. We call this new measure the
tidal circularization period. The tidal circularization period of a binary
population represents the orbital period at which a binary orbit with the most
frequent initial orbital eccentricity circularizes (defined as e = 0.01) at the
age of the population. We determine the tidal circularizationperiod for M35 as
well as for 7 additional binary populations spanning ages from the pre
main-sequence (~ 3 Myr) to late main-sequence (~ 10 Gyr), and use Monte Carlo
error analysis to determine the uncertainties on the derived circularization
periods. We conclude that current theories of tidal circularization cannot
account for the distribution of tidal circularization periods with population
age.Comment: 37 pages, 9 figures, to be published in The Astrophysical Journal,
February 200
Dynamical Tide in Solar-Type Binaries
Circularization of late-type main-sequence binaries is usually attributed to
turbulent convection, while that of early-type binaries is explained by
resonant excitation of g modes. We show that the latter mechanism operates in
solar-type stars also and is at least as effective as convection, despite
inefficient damping of g modes in the radiative core. The maximum period at
which this mechanism can circularize a binary composed of solar-type stars in
10 Gyr is as low as 3 days, if the modes are damped by radiative diffusion only
and g-mode resonances are fixed; or as high as 6 days, if one allows for
evolution of the resonances and for nonlinear damping near inner turning
points. Even the larger theoretical period falls short of the observed
transition period by a factor two.Comment: 17 pages, 2 postscript figures, uses aaspp4.sty. Submitted to Ap
Seismic tests for solar models with tachocline mixing
We have computed accurate 1-D solar models including both a macroscopic
mixing process in the solar tachocline as well as up-to-date microscopic
physical ingredients. Using sound speed and density profiles inferred through
primary inversion of the solar oscillation frequencies coupled with the
equation of thermal equilibrium, we have extracted the temperature and hydrogen
abundance profiles. These inferred quantities place strong constraints on our
theoretical models in terms of the extent and strength of our macroscopic
mixing, on the photospheric heavy elements abundance, on the nuclear reaction
rates such as and and on the efficiency of the microscopic
diffusion. We find a good overall agreement between the seismic Sun and our
models if we introduce a macroscopic mixing in the tachocline and allow for
variation within their uncertainties of the main physical ingredients. From our
study we deduce that the solar hydrogen abundance at the solar age is and that based on the Be photospheric depletion, the
maximum extent of mixing in the tachocline is 5% of the solar radius. The
nuclear reaction rate for the fundamental reaction is found to be
MeV barns, i.e., 1.5% higher than the
present theoretical determination. The predicted solar neutrino fluxes are
discussed in the light of the new SNO/SuperKamiokande results.Comment: 16 pages, 12 figures, A&A in press (1) JILA, University of Colorado,
Boulder, CO 80309-0440, USA, (2) LUTH, Observatoire de Paris-Meudon, 92195
Meudon, France, (3) Tata Institute of Fundamental Research, Homi Bhabha road,
Mumbai 400005, India, (4) Department of Physics, University of Mumbai, Mumbai
400098, Indi
Delensing CMB Polarization with External Datasets
One of the primary scientific targets of current and future CMB polarization
experiments is the search for a stochastic background of gravity waves in the
early universe. As instrumental sensitivity improves, the limiting factor will
eventually be B-mode power generated by gravitational lensing, which can be
removed through use of so-called delensing algorithms. We forecast prospects
for delensing using lensing maps which are obtained externally to CMB
polarization: either from large-scale structure observations, or from
high-resolution maps of CMB temperature. We conclude that the forecasts in
either case are not encouraging, and that significantly delensing large-scale
CMB polarization requires high-resolution polarization maps with sufficient
sensitivity to measure the lensing B-mode. We also present a simple formalism
for including delensing in CMB forecasts which is computationally fast and
agrees well with Monte Carlos.Comment: typos correcte
The Problem of Characterizing the 4QReworked Pentateuch Manuscripts: Bible, Rewritten Bible, or None of the Above?
This is the author's accepted manuscript. The original is available at http://booksandjournals.brillonline.com/content/journals/10.1163/156851708x304895This article engages the problem of whether the five manuscripts classified as 4QReworked Pentateuch (4Q158, 4Q364–367) should be considered extrabiblical compositions or simply expansive copies of the Pentateuch. Since similar methods of reworking scripture appear in both types of text, focusing on the ways scripture is reworked in the 4QRP manuscripts cannot solve the problem. Other criteria such as the literary voice, scope, and coverage of a work are more promising. The fragmentary state of the texts, however, precludes a definitive solution and requires that multiple possibilities be considered
The Samaritan Pentateuch and the Scribal Culture of Second Temple Judaism
This is the author's accepted manuscript. The original is available at http://booksandjournals.brillonline.com/content/journals/10.1163/15700631-12340103The Samaritan Pentateuch (SP), along with its Qumran forebears, has deservedly been regarded as a key source of information for understanding the scribal culture of early Judaism. Yet studies have tended to emphasize the relative uniformity of the characteristic pre-SP readings as evidence of a scribal approach distinct within Second Temple Judaism. This article argues that both the uniformity and the distinctiveness of these readings have been overstated: there is more internal diversity within pre-SP than is usually recognized, and similar or identical readings are also preserved in other manuscript traditions. Rather than representing a distinctive scribal approach or school, the readings of pre-SP are better taken as a particularly concentrated example of scribal attitudes and techniques that appear to have been widespread in early Judaism
Genre and Rewritten Scripture: A Reassessment
This is the author's accepted manuscript. The original is available at http://muse.jhu.edu/journals/journal_of_biblical_literature/v131/131.2.zahn.htm
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