482 research outputs found
Minimal Supersymmetric CPN Models
Supersymmetric CPN models based on underlying bosonic Kahler manifolds have
not been thought to arise directly from constrained linear ones. A
counterexample for N=4 is presented using improved understanding of membranes
in superstring theories leading to crucial central terms modifying the algebra
of supercharge densities. The example has an immediate extension to all higher
N
Avoiding the theorem of Lerche and Shore
Supersymmetric -models obtained by constraining linear supersymmetric
field theories are ill defined. Well defined subsectors parametrising Kahler
manifolds exist but are not believed to arise directly from constrained linear
ones. A counterexample is offered using improved understanding of membranes in
superstring theories leading to crucial central terms modifying the algebra of
supercharge densitie
Constructing Hybrid Baryons with Flux Tubes
Hybrid baryon states are described in quark potential models as having
explicit excitation of the gluon degrees of freedom. Such states are described
in a model motivated by the strong coupling limit of Hamiltonian lattice gauge
theory, where three flux tubes meeting at a junction play the role of the glue.
The adiabatic approximation for the quark motion is used, and the flux tubes
and junction are modeled by beads which are attracted to each other and the
quarks by a linear potential, and vibrate in various string modes. Quantum
numbers and estimates of the energies of the lightest hybrid baryons are
provided.Comment: 4 pages, RevTeX. Submitted to Physical Review Letter
Reply to "Comment on "Some implications of the quantum nature of laser fields for quantum computations''''
In this revised reply to quant-ph/0211165, I address the question of the
validity of my results in greater detail, by comparing my predictions to those
of the Silberfarb-Deutsch model, and I deal at greater length with the beam
area paradox. As before, I conclude that my previous results are an
(order-of-magnitude) accurate estimate of the error probability introduced in
quantum logical operations by the quantum nature of the laser field. While this
error will typically (for a paraxial beam) be smaller than the total error due
to spontaneous emission, a unified treatment of both effects reveals that they
lead to formally similar constraints on the minimum number of photons per pulse
required to perform an operation with a given accuracy; these constraints agree
with those I have derived elsewhere.Comment: A reply to quant-ph/0211165. Added more calculations and discussion,
removed some flippanc
Measurement of hybrid content of heavy quarkonia using lattice NRQCD
Using lowest-order lattice NRQCD to create heavy meson propagators and
applying the spin-dependent interaction, , at varying intermediate time slices, we
compute the off-diagonal matrix element of the Hamiltonian for the
quarkonium-hybrid two-state system. Thus far, we have results for one set of
quenched lattices with an interpolation in quark mass to match the bottomonium
spectrum. After diagonalization of the two-state Hamiltonian, we find the
ground state of the to show a (with ) probability admixture of hybrid, .Comment: 11 pages, 4 figures, to appear in Phys Rev
Ridge Formation and De-Spinning of Iapetus via an Impact-Generated Satellite
We present a scenario for building the equatorial ridge and de-spinning
Iapetus through an impact-generated disk and satellite. This impact puts debris
into orbit, forming a ring inside the Roche limit and a satellite outside. This
satellite rapidly pushes the ring material down to the surface of Iapetus, and
then itself tidally evolves outward, thereby helping to de-spin Iapetus. This
scenario can de-spin Iapetus an order of magnitude faster than when tides due
to Saturn act alone, almost independently of its interior geophysical
evolution. Eventually, the satellite is stripped from its orbit by Saturn. The
range of satellite and impactor masses required is compatible with the
estimated impact history of Iapetus.Comment: 19 pages, 3 figures; Icarus, in pres
A Supersymmetric Effective Chiral Lagrangian
We construct in a manifestly supersymmetric form the leading and subleading
terms in momentum for an effective supersymmetric chiral Lagrangian in terms of
complex pions and their superpartners. A soft supersymmetry breaking term is
included and below the supersymmetry breaking scale the Lagrangian reduces to
the usual bosonic chiral Lagrangian in terms of real pions.Comment: University of Southampton preprint no. SHEP 93/94-12 LATE
Hybrid configuration content of heavy S-wave mesons
We use the non-relativistic expansion of QCD (NRQCD) on the lattice to study
the lowest hybrid configuration contribution to the ground state of heavy
S-wave mesons. Using lowest-order lattice NRQCD to create the heavy-quark
propagators, we form a basis of ``unperturbed'' S-wave and hybrid states. We
then apply the lowest-order coupling of the quark spin and chromomagnetic field
at an intermediate time slice to create ``mixed'' correlators between the
S-wave and hybrid states. From the resulting amplitudes, we extract the
off-diagonal element of our two-state Hamiltonian. Diagonalizing this
Hamiltonian gives us the admixture of hybrid configuration within the meson
ground state. The present effort represents a continuation of previous work:
the analysis has been extended to include lattices of varying spacings, source
operators having better overlap with the ground states, and the pseudoscalar
(along with the vector) channel. Results are presented for bottomonium
(, ) using three different sets of quenched lattices. We
also show results for charmonium (, ) from one lattice set,
although we note that the non-relativistic approximation is not expected to be
very good in this case.Comment: 9 pages, 7 figures, version to appear in Phys Rev
Relativistic Coulomb Sum Rules for
A Coulomb sum rule is derived for the response of nuclei to
scattering with large three-momentum transfers. Unlike the nonrelativistic
formulation, the relativistic Coulomb sum is restricted to spacelike
four-momenta for the most direct connection with experiments; an immediate
consequence is that excitations involving antinucleons, e.g., pair
production, are approximately eliminated from the sum rule. Relativistic recoil
and Fermi motion of target nucleons are correctly incorporated. The sum rule
decomposes into one- and two-body parts, with correlation information in the
second. The one-body part requires information on the nucleon momentum
distribution function, which is incorporated by a moment expansion method. The
sum rule given through the second moment (RCSR-II) is tested in the Fermi gas
model, and is shown to be sufficiently accurate for applications to data.Comment: 32 pages (LaTeX), 4 postscript figures available from the author
Spontaneous chiral symmetry breaking in the linked cluster expansion
We investigate dynamical chiral symmetry breaking in the Coulomb gauge
Hamiltonian QCD. Within the framework of the linked cluster expansion we extend
the BCS ansatz for the vacuum and include correlation beyond the
quark-antiquark paring. In particular we study the effects of the three-body
correlations involving quark-antiquark and transverse gluons. The high momentum
behavior of the resulting gap equation is discussed and numerical computation
of the chiral symmetry breaking is presented.Comment: 13 pages, 9 figure
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