16,836 research outputs found
Binary spinning black hole Hamiltonian in canonical center-of-mass and rest-frame coordinates through higher post-Newtonian order
The recently constructed Hamiltonians for spinless binary black holes through
third post-Newtonian order and for spinning ones through formal second
post-Newtonian order, where the spins are counted of zero post-Newtonian order,
are transformed into fully canonical center-of-mass and rest-frame variables.
The mixture terms in the Hamiltonians between center-of-mass and rest-frame
variables are in accordance with the relation between the total linear momentum
and the center-of-mass velocity as demanded by global Lorentz invariance. The
various generating functions for the center-of-mass and rest-frame canonical
variables are explicitly given in terms of the single-particle canonical
variables. The no-interaction theorem does not apply because the world-line
condition of Lorentz covariant position variables is not imposed.Comment: 18 pages, no figure
Binary spinning black hole Hamiltonian in canonical center-of-mass and rest-frame coordinates through higher post-Newtonian order
The recently constructed Hamiltonians for spinless binary black holes through
third post-Newtonian order and for spinning ones through formal second
post-Newtonian order, where the spins are counted of zero post-Newtonian order,
are transformed into fully canonical center-of-mass and rest-frame variables.
The mixture terms in the Hamiltonians between center-of-mass and rest-frame
variables are in accordance with the relation between the total linear momentum
and the center-of-mass velocity as demanded by global Lorentz invariance. The
various generating functions for the center-of-mass and rest-frame canonical
variables are explicitly given in terms of the single-particle canonical
variables. The no-interaction theorem does not apply because the world-line
condition of Lorentz covariant position variables is not imposed.Comment: 18 pages, no figure
Elliptic flow of the dilute Fermi gas: From kinetics to hydrodynamics
We use the Boltzmann equation in the relaxation time approximation to study
the expansion of a dilute Fermi gas at unitarity. We focus, in particular, on
the approach to the hydrodynamic limit. Our main finding are: i) In the regime
that has been studied experimentally hydrodynamic effects beyond the
Navier-Stokes approximation are small, ii) mean field corrections to the
Boltzmann equation are not important, iii) experimental data imply that
freezeout occurs very late, that means that the relaxation time remains smaller
than the expansion time during the entire evolution of the system, iv) the
experimental results also imply that the bulk viscosity is significantly
smaller than the shear viscosity of the system.Comment: 18 pages, 6 figure
Cold dilute neutron matter on the lattice II: Results in the unitary limit
This is the second of two papers which investigate cold dilute neutron matter
on the lattice using pionless effective field theory. In the unitary limit,
where the effective range is zero and scattering length is infinite, simple
scaling relations relate thermodynamic functions at different temperatures.
When the second virial coefficient is properly tuned, we find that the lattice
results obey these scaling relations. We compute the energy per particle,
pressure, spin susceptibility, dineutron correlation function, and an upper
bound for the superfluid critical temperature.Comment: 16 pages, 9 figure
Meson Masses in High Density QCD
The low-energy effective theories for the two- and three-flavor
color-superconductors arising in the high density limit of QCD are discussed.
Using an effective field theory to describe quarks near the fermi surface, we
compute the masses of the pseudo-Goldstone bosons that dominate the
low-momentum dynamics of these systems.Comment: 13 pages, 3 figures, late
Stress Tensor and Bulk Viscosity in Relativistic Nuclear Collisions
We discuss the influence of different initial conditions for the stress
tensor and the effect of bulk viscosity on the expansion and cooling of the
fireball created in relativistic heavy-ion collisions. In particular, we
explore the evolution of longitudinal and transverse components of the pressure
and the extent of dissipative entropy production in the one-dimensional,
boost-invariant hydrodynamic model. We find that a bulk viscosity consistent
with recent estimates from lattice QCD further slows the equilibration of the
system, however it does not significantly increase the entropy produced
Gaussian matrix-product states for coding in bosonic communication channels
The communication capacity of Gaussian bosonic channels with memory has
recently attracted much interest. Here, we investigate a method to prepare the
multimode entangled input symbol states for encoding classical information into
these channels. In particular, we study the usefulness of a Gaussian matrix
product state (GMPS) as an input symbol state, which can be sequentially
generated although it remains heavily entangled for an arbitrary number of
modes. We show that the GMPS can achieve more than 99.9% of the Gaussian
capacity for Gaussian bosonic memory channels with a Markovian or non-Markovian
correlated noise model in a large range of noise correlation strengths.
Furthermore, we present a noise class for which the GMPS is the exact optimal
input symbol state of the corresponding channel. Since GMPS are ground states
of particular quadratic Hamiltonians, our results suggest a possible link
between the theory of quantum communication channels and quantum many-body
physics.Comment: 7 pages, 5 figures. v2: Refs. modified, typos correcte
- …