2,695 research outputs found
Using Full Information When Computing Modes of Post-Newtonian Waveforms From Inspiralling Compact Binaries in Circular Orbit
The increasing sophistication and accuracy of numerical simulations of
compact binaries (especially binary black holes) presents the opportunity to
test the regime in which post-Newtonian (PN) predictions for the emitted
gravitational waves are accurate. In order to confront numerical results with
those of post-Newtonian theory, it is convenient to compare multipolar
decompositions of the two waveforms. It is pointed out here that the individual
modes can be computed to higher post-Newtonian order by examining the radiative
multipole moments of the system, rather than by decomposing the 2.5PN
polarization waveforms. In particular, the dominant (l = 2, m = 2) mode can be
computed to 3PN order. Individual modes are computed to as high a
post-Newtonian order as possible given previous post-Newtonian results.Comment: 15 page
Coherent States and N Dimensional Coordinate Noncommutativity
Considering coordinates as operators whose measured values are expectations
between generalized coherent states based on the group SO(N,1) leads to
coordinate noncommutativity together with full dimensional rotation
invariance. Through the introduction of a gauge potential this theory can
additionally be made invariant under dimensional translations. Fluctuations
in coordinate measurements are determined by two scales. For small distances
these fluctuations are fixed at the noncommutativity parameter while for larger
distances they are proportional to the distance itself divided by a {\em very}
large number. Limits on this number will lbe available from LIGO measurements.Comment: 16 pqges. LaTeX with JHEP.cl
Searches for New Quarks and Leptons Produced in Z-Boson Decay
We have searched for events with new-particle topologies in 390 hadronic Z decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower limits of 40.7 GeV/c^2 for the top-quark mass, 42.0 GeV/c^2 for the mass of a fourth-generation charge - 1/3 quark, and 41.3 GeV/c^2 for the mass of an unstable Dirac neutral lepton
Measurement of Z Decays into Lepton Pairs
We present measurements by the Mark II experiment of the ratios of the leptonic partial widths of the Z boson to the hadronic partial width. The results are Î_(ee)/Î_(had)=0.037_(-0.012^()+0.016),Î_(””)/Î_(had)=0.053-_(0.015)^(+0.020), and Î_(ÏÏ)/Î_(had)=0.066_(-0.017)^(+0.021), in good agreement with the standard-model prediction of 0.048. From the average leptonic width result, Î_(ll)/Î_(had)=0.053_(-0.009)^(+0.010), we derive Î_(had)=1.56_(-0.24)^(+0.28) GeV. We find for the vector coupling constants of the tau and muon v_Ï^2=0.31±0.31_(-0.30)^(+0.43) and v_ÎŒ^2=0.05±0.30_(-0.23)^(+0.34)
Binary pattern tile set synthesis is NP-hard
In the field of algorithmic self-assembly, a long-standing unproven
conjecture has been that of the NP-hardness of binary pattern tile set
synthesis (2-PATS). The -PATS problem is that of designing a tile assembly
system with the smallest number of tile types which will self-assemble an input
pattern of colors. Of both theoretical and practical significance, -PATS
has been studied in a series of papers which have shown -PATS to be NP-hard
for , , and then . In this paper, we close the
fundamental conjecture that 2-PATS is NP-hard, concluding this line of study.
While most of our proof relies on standard mathematical proof techniques, one
crucial lemma makes use of a computer-assisted proof, which is a relatively
novel but increasingly utilized paradigm for deriving proofs for complex
mathematical problems. This tool is especially powerful for attacking
combinatorial problems, as exemplified by the proof of the four color theorem
by Appel and Haken (simplified later by Robertson, Sanders, Seymour, and
Thomas) or the recent important advance on the Erd\H{o}s discrepancy problem by
Konev and Lisitsa using computer programs. We utilize a massively parallel
algorithm and thus turn an otherwise intractable portion of our proof into a
program which requires approximately a year of computation time, bringing the
use of computer-assisted proofs to a new scale. We fully detail the algorithm
employed by our code, and make the code freely available online
Model-Independent Semileptonic Form Factors Using Dispersion Relations
We present a method for parametrizing heavy meson semileptonic form factors
using dispersion relations, and from it produce a two-parameter description of
the B -> B elastic form factor. We use heavy quark symmetry to relate this
function to B -> D* l nu form factors, and extract
|V_cb|=0.0355^{+0.0029}_{-0.0025} from experimental data with a least squares
fit. Our method eliminates model-dependent uncertainties inherent in choosing a
parametrization for the extrapolation of the differential decay rate to
threshold.Comment: uses lanlmac(harvmac) and epsf, 12 pages, 1 eps figure included (Talk
by BG at the 6-th International Symposium on Heavy Flavour Physics, Pisa,
Italy, 6--10 June, 1995
Parameter estimation of compact binaries using the inspiral and ringdown waveforms
We analyze the problem of parameter estimation for compact binary systems
that could be detected by ground-based gravitational wave detectors.
So far this problem has only been dealt with for the inspiral and the
ringdown phases separately. In this paper, we combine the information from both
signals, and we study the improvement in parameter estimation, at a fixed
signal-to-noise ratio, by including the ringdown signal without making any
assumption on the merger phase. The study is performed for both initial and
advanced LIGO and VIRGO detectors.Comment: matching cqg versio
Super-Kamiokande atmospheric neutrinos: Status of subdominant oscillations
In the context of the recent (79.5 kTy) Super-Kamiokande atmospheric neutrino
data, we concisely review the status of muonic-tauonic flavor oscillations and
of the subdominant electron or sterile neutrino mixing, in schemes with three
or four families and one dominant mass scale. In the three-family case, where
we include the full CHOOZ spectral data, we also show, through a specific
example, that ``maximal'' violations of the one-dominant mass scale
approximation are not ruled out yet.Comment: 8 pages + 10 figure
Optimal self-assembly of finite shapes at temperature 1 in 3D
Working in a three-dimensional variant of Winfree's abstract Tile Assembly
Model, we show that, for an arbitrary finite, connected shape , there is a tile set that uniquely self-assembles into a 3D
representation of a scaled-up version of at temperature 1 in 3D with
optimal program-size complexity (the "program-size complexity", also known as
"tile complexity", of a shape is the minimum number of tile types required to
uniquely self-assemble it). Moreover, our construction is "just barely" 3D in
the sense that it only places tiles in the and planes. Our
result is essentially a just-barely 3D temperature 1 simulation of a similar 2D
temperature 2 result by Soloveichik and Winfree (SICOMP 2007)
Rethinking the social impacts of the arts
The paper presents a critical discussion of the current debate over the social impacts of the arts in the UK. It argues that the accepted understanding of the terms of the debate is rooted in a number of assumptions and beliefs that are rarely questioned. The paper goes on to present the interim findings of a threeâyear research project, which aims to rethink the social impact of the arts, with a view to determining how these impacts might be better understood. The desirability of a historical approach is articulated, and a classification of the claims made within the Western intellectual tradition for what the arts âdoâ to people is presented and discussed
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