30,638 research outputs found

### Excited nucleon spectrum from lattice QCD with maximum entropy method

We study excited states of the nucleon in quenched lattice QCD with the
spectral analysis using the maximum entropy method. Our simulations are
performed on three lattice sizes $16^3\times 32$, $24^3\times 32$ and
$32^3\times 32$, at $\beta=6.0$ to address the finite volume issue. We find a
significant finite volume effect on the mass of the Roper resonance for light
quark masses. After removing this systematic error, its mass becomes
considerably reduced toward the direction to solve the level order puzzle
between the Roper resonance $N'(1440)$ and the negative-parity nucleon
$N^*(1535)$.Comment: Lattice2003(spectrum), 3 pages, 4 figure

### Gap Condition and Self-Dualized ${\cal N}=4$ Super Yang-Mills Theory for ADE Gauge Group on K3

We try to determine the partition function of ${\cal N}=4$ super Yang-Mills
theoy for ADE gauge group on K3 by self-dualizing our previous ADE partition
function. The resulting partition function satisfies gap condition.Comment: 17 page

### Realization of a collective decoding of codeword states

This was also extended from the previous article quant-ph/9705043, especially
in a realization of the decoding process.Comment: 6 pages, RevTeX, 4 figures(EPS

### Bayesian approach to the first excited nucleon state in lattice QCD

We present preliminary results from the first attempt to reconstruct the
spectral function in the nucleon and $\Delta$ channels from lattice QCD data
using the maximum entropy method (MEM). An advantage of the MEM analysis is to
enable us to access information of the excited state spectrum. Performing
simulations on two lattice volumes, we confirm the large finite size effect on
the first excited nucleon state in the lighter quark mass region.Comment: Lattice2002(spectrum), Latex with espcrc2.sty, 3 pages, 3 figure

### Non-Linear Sigma Models on a Half Plane

In the context of integrable field theory with boundary, the integrable
non-linear sigma models in two dimensions, for example, the $O(N)$, the
principal chiral, the ${\rm CP}^{N-1}$ and the complex Grassmannian sigma
models are discussed on a half plane. In contrast to the well known cases of
sine-Gordon, non-linear Schr\"odinger and affine Toda field theories, these
non-linear sigma models in two dimensions are not classically integrable if
restricted on a half plane. It is shown that the infinite set of non-local
charges characterising the integrability on the whole plane is not conserved
for the free (Neumann) boundary condition. If we require that these non-local
charges to be conserved, then the solutions become trivial.Comment: 25 pages, latex, no figure

### Virtual photon structure functions and positivity constraints

We study the three positivity constraints among the eight virtual photon
structure functions, derived from the Cauchy-Schwarz inequality and which are
hence model-independent. The photon structure functions obtained from the
simple parton model show quite different behaviors in a massive quark or a
massless quark case, but they satisfy, in both cases, the three positivity
constraints. We then discuss an inequality which holds among the unpolarized
and polarized photon structure functions $F_1^\gamma$, $g_1^\gamma$ and
$W_{TT}^\tau$, in the kinematic region $\Lambda^2\ll P^2 \ll Q^2$, where $-Q^2
(-P^2)$ is the mass squared of the probe (target) photon, and we examine
whether this inequality is satisfied by the perturbative QCD results.Comment: 24 pages, 13 eps figure

### Evaluation of specific heat for superfluid helium between 0 - 2.1 K based on nonlinear theory

The specific heat of liquid helium was calculated theoretically in the Landau
theory. The results deviate from experimental data in the temperature region of
1.3 - 2.1 K. Many theorists subsequently improved the results of the Landau
theory by applying temperature dependence of the elementary excitation energy.
As well known, many-body system has a total energy of Galilean covariant form.
Therefore, the total energy of liquid helium has a nonlinear form for the
number distribution function. The function form can be determined using the
excitation energy at zero temperature and the latent heat per helium atom at
zero temperature. The nonlinear form produces new temperature dependence for
the excitation energy from Bose condensate. We evaluate the specific heat using
iteration method. The calculation results of the second iteration show good
agreement with the experimental data in the temperature region of 0 - 2.1 K,
where we have only used the elementary excitation energy at 1.1 K.Comment: 6 pages, 3 figures, submitted to Journal of Physics: Conference
Serie

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