9,908 research outputs found
On-shell Delta I = 3/2 kaon weak matrix elements with non-zero total momentum
We present our results for the on-shell Delta I = 3/2 kaon decay matrix
elements using domain wall fermions and the DBW2 gauge action at one coarse
lattice spacing corresponding to 1/a = 1.31 GeV in the quenched approximation.
The on-shell matrix elements are evaluated in two different frames: the
center-of-mass frame and non-zero total-momentum frame. We employ the formula
proposed by Lellouch and L\"uscher in the center-of-mass frame, and its
extension for non-zero total momentum frame to extract the infinite volume,
on-shell, center-of-mass frame decay amplitudes. We determine the decay
amplitude at the physical pion mass and momentum from the chiral extrapolation
and an interpolation of the relative momentum using the results calculated in
the two frames. We have obtained Re(A_2) = 1.66(23)(^{+48}_{-03})(^{+53}_{-0})
x 10^{-8} GeV and Im(A_2) = -1.181(26)(^{+141}_{-014})(^{+44}_{-0}) x 10^{-12}
GeV at the physical point, using the data at the relatively large pion mass,
m_pi > 0.35 GeV. The first error is statistic, and the second and third are
systematic. The second error is estimated with several fits of the chiral
extrapolation including (quenched) chiral perturbation formula at next to
leading order using only lighter pion masses. The third one is estimated with
an analysis using the lattice dispersion relation. The result of Re(A_2) is
reasonably consistent with experiment.Comment: 54 pages, 17 figures; added references, removed figure and corrected
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QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments
QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments
Nucleon structure with two flavors of dynamical domain-wall fermions
We present a numerical lattice quantum chromodynamics calculation of
isovector form factors and the first few moments of the isovector structure
functions of the nucleon. The calculation employs two degenerate dynamical
flavors of domain-wall fermions, resulting in good control of chiral symmetry
breaking. Non-perturbative renormalization of the relevant quark currents is
performed where necessary. The inverse lattice spacing, , is about 1.7
GeV. We use degenerate up and down dynamical quark masses around 1, 3/4 and 1/2
the strange quark mass. The physical volume of the lattice is about
. The ratio of the isovector vector to axial charges, ,
trends a bit lower than the experimental value as the quark mass is reduced
toward the physical point. We calculate the momentum-transfer dependences of
the isovector vector, axial, induced tensor and induced pseudoscalar form
factors. The Goldberger-Treiman relation holds at low momentum transfer and
yields a pion-nucleon coupling, , where the quoted
error is only statistical. We find that the flavor non-singlet quark momentum
fraction and quark helicity fraction
overshoot their experimental values after linear chiral extrapolation. We
obtain the transversity, in
at 2 GeV and a twist-3 polarized moment, , appears small, suggesting that
the Wandzura-Wilczek relation holds approximately. We discuss the systematic
errors in the calculation, with particular attention paid to finite-volume
effects, excited-state contamination, and chiral extrapolations.Comment: 28 pages in two columns; 37 figures, 12 table
Global well-posedness of the Kirchhoff equation and Kirchhoff systems
This article is devoted to review the known results on global well-posedness
for the Cauchy problem to the Kirchhoff equation and Kirchhoff systems with
small data. Similar results will be obtained for the initial-boundary value
problems in exterior domains with compact boundary. Also, the known results on
large data problems will be reviewed together with open problems.Comment: arXiv admin note: text overlap with arXiv:1211.300
Nucleon isovector structure functions in (2+1)-flavor QCD with domain wall fermions
We report on numerical lattice QCD calculations of some of the low moments of
the nucleon structure functions. The calculations are carried out with gauge
configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors
of dynamical domain wall fermions and the Iwasaki gauge action (). The inverse lattice spacing is GeV, and two spatial
volumes of ((2.7{\rm fm})^3) and ((1.8 {\rm fm})^3) are used. The up and down
quark masses are varied so the pion mass lies between 0.33 and 0.67 GeV while
the strange mass is about 12 % heavier than the physical one. The structure
function moments we present include fully non-perturbatively renormalized
iso-vector quark momentum fraction, (_{u-d}), helicity fraction, (< x
>_{\Delta u - \Delta d}), and transversity, (_{\delta u - \delta d}), as
well as an unrenormalized twist-3 coefficient, (d_1). The ratio of the momentum
to helicity fractions, (_{u-d}/_{\Delta u - \Delta d}), does not show
dependence on the light quark mass and agrees well with the value obtained from
experiment. Their respective absolute values, fully renormalized, show
interesting trends toward their respective experimental values at the lightest
quark mass. A prediction for the transversity, (0.7 _{\delta u -\delta
d} < 1.1), in the (\bar{\rm MS}) scheme at 2 GeV is obtained. The twist-3
coefficient, (d_1), though yet to be renormalized, supports the perturbative
Wandzura-Wilczek relation.Comment: 14 pages, 22 figures
Quantum Parton Shower with Kinematics
Parton showers which can efficiently incorporate quantum interference effects
have been shown to be run efficiently on quantum computers. However, so far
these quantum parton showers did not include the full kinematical information
required to reconstruct an event, which in classical parton showers requires
the use of a veto algorithm. In this work, we show that adding one extra
assumption about the discretization of the evolution variable allows to
construct a quantum veto algorithm, which reproduces the full quantum
interference in the event, and allows to include kinematical effects. We
finally show that for certain initial states the quantum interference effects
generated in this veto algorithm are classically tractable, such that an
efficient classical algorithm can be devised.Comment: 14 pages, 8 figure
Asymptotically optimal Bayesian sequential change detection and identification rules
Cataloged from PDF version of article.We study the joint problem of sequential change detection and multiple hypothesis
testing. Suppose that the common distribution of a sequence of i.i.d. random variables
changes suddenly at some unobservable time to one of finitely many distinct alternatives,
and one needs to both detect and identify the change at the earliest possible time. We propose
computationally efficient sequential decision rules that are asymptotically either Bayesoptimal
or optimal in a Bayesian fixed-error-probability formulation, as the unit detection
delay cost or the misdiagnosis and false alarm probabilities go to zero, respectively. Numerical
examples are provided to verify the asymptotic optimality and the speed of convergence
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Quantum parton shower with kinematics
Parton showers, which can efficiently incorporate quantum interference effects, have been shown to be run efficiently on quantum computers. However, so far these quantum parton showers have not included the full kinematical information required to reconstruct an event, which in classical parton showers requires the use of a veto algorithm. In this work, we show that adding one extra assumption about the discretization of the evolution variable allows one to construct a quantum veto algorithm, which reproduces the full quantum interference in the event, and allows one to include kinematical effects. We finally show that for certain initial states the quantum interference effects generated in this veto algorithm are classically tractable, such that an efficient classical algorithm can be devised
Gravitational Wave Memory of Gamma-Ray Burst Jets
Gamma-Ray Bursts (GRBs) are now considered as relativistic jets. We analyze
the gravitational waves from the acceleration stage of the GRB jets. We show
that (i) the point mass approximation is not appropriate if the opening
half-angle of the jet is larger than the inverse of the Lorentz factor of the
jet, (ii) the gravitational waveform has many step function like jumps, and
(iii) the practical DECIGO and BBO may detect such an event if the GRBs occur
in Local group of galaxy. We found that the light curve of GRBs and the
gravitational waveform are anti-correlated so that the detection of the
gravitational wave is indispensable to determine the structure of GRB jets.Comment: Revtex4, 10 pages, 6 figures, Fig.2 and Fig.3 replaced, minor changes
to text in Sec.I and Sec.V, typos corrected, some reference added, Version to
be published in PR
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