125,771 research outputs found
Solutions of special asymptotics to the Einstein constraint equations
We construct solutions with prescribed asymptotics to the Einstein constraint
equations using a cut-off technique. Moreover, we give various examples of
vacuum asymptotically flat manifolds whose center of mass and angular momentum
are ill-defined.Comment: 13 pages; the error in Lemma 3.5 fixed and typos corrected; to appear
in Class. Quantum Gra
Transition Temperature of a Uniform Imperfect Bose Gas
We calculate the transition temperature of a uniform dilute Bose gas with
repulsive interactions, using a known virial expansion of the equation of
state. We find that the transition temperature is higher than that of an ideal
gas, with a fractional increase K_0(na^3)^{1/6}, where n is the density and a
is the S-wave scattering length, and K_0 is a constant given in the paper. This
disagrees with all existing results, analytical or numerical. It agrees exactly
in magnitude with a result due to Toyoda, but has the opposite sign.Comment: Email correspondence to [email protected] ; 2 pages using REVTe
A variational principle for fluid sloshing with vorticity, dynamically coupled to vessel motion
A variational principle is derived for two-dimensional incompressible
rotational fluid flow with a free surface in a moving vessel when both the
vessel and fluid motion are to be determined. The fluid is represented by a
stream function and the vessel motion is represented by a path in the planar
Euclidean group. Novelties in the formulation include how the pressure boundary
condition is treated, the introduction of a stream function into the
Euler-Poincar\'e variations, the derivation of free surface variations, and how
the equations for the vessel path in the Euclidean group, coupled to the fluid
motion, are generated automatically.Comment: 19 pages, 3 figure
Information on the Pion Distribution Amplitude from the Pion-Photon Transition Form Factor with the Belle and BaBar Data
The pion-photon transition form factor (TFF) provides strong constraints on
the pion distribution amplitude (DA). We perform an analysis of all existing
data (CELLO, CLEO, BaBar, Belle) on the pion-photon TFF by means of light-cone
pQCD approach in which we include the next-to-leading order correction to the
valence-quark contribution and estimate the non-valence-quark contribution by a
phenomenological model based on the TFF's limiting behavior at both
and . At present, the pion DA is not definitely determined, it is
helpful to have a pion DA model that can mimic all the suggested behaviors,
especially to agree with the constraints from the pion-photon TFF in whole
measured region within a consistent way. For the purpose, we adopt the
conventional model for pion wavefunction/DA that has been constructed in our
previous paper \cite{hw1}, whose broadness is controlled by a parameter . We
fix the DA parameters by using the CELLO, CLEO, BABAR and Belle data within the
smaller region ( GeV), where all the data are consistent
with each other. And then the pion-photon TFF is extrapolated into larger
region. We observe that the BABAR favors which has the behavior close
to the Chernyak-Zhitnitsky DA, whereas the recent Belle favors which
is close to the asymptotic DA. We need more accurate data at large region
to determine the precise value of , and the definite behavior of pion DA can
be concluded finally by the consistent data in the coming future.Comment: 6 pages, 5 figures. Slightly changed and references update
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