800 research outputs found
Survival of charmonia above Tc in anisotropic lattice QCD
We find a strong evidence for the survival of and as
spatially-localized (quasi-)bound states above the QCD critical
temperature , by investigating the boundary-condition dependence of their
energies and spectral functions. In a finite-volume box, there arises a
boundary-condition dependence for spatially spread states, while no such
dependence appears for spatially compact states. In lattice QCD, we find almost
{\it no} spatial boundary-condition dependence for the energy of the
system in and channels for . We also
investigate the spectral function of charmonia above in lattice QCD using
the maximum entropy method (MEM) in terms of the boundary-condition dependence.
There is {\it no} spatial boundary-condition dependence for the low-lying peaks
corresponding to and around 3GeV at . These facts
indicate the survival of and as compact
(quasi-)bound states for .Comment: 4 pages, 1 figur
Integral representations of q-analogues of the Hurwitz zeta function
Two integral representations of q-analogues of the Hurwitz zeta function are
established. Each integral representation allows us to obtain an analytic
continuation including also a full description of poles and special values at
non-positive integers of the q-analogue of the Hurwitz zeta function, and to
study the classical limit of this q-analogue. All the discussion developed here
is entirely different from the previous work in [4]Comment: 14 page
Charmonium properties in deconfinement phase in anisotropic lattice QCD
J/Psi and eta_c above the QCD critical temperature T_c are studied in
anisotropic quenched lattice QCD, considering whether the c\bar c systems above
T_c are spatially compact (quasi-)bound states or scattering states. We adopt
the standard Wilson gauge action and O(a)-improved Wilson quark action with
renormalized anisotropy a_s/a_t =4.0 at \beta=6.10 on 16^3\times (14-26)
lattices, which correspond to the spatial lattice volume V\equiv
L^3\simeq(1.55{\rm fm})^3 and temperatures T\simeq(1.11-2.07)T_c. We
investigate the c\bar c system above T_c from the temporal correlators with
spatially-extended operators, where the overlap with the ground state is
enhanced. To clarify whether compact charmonia survive in the deconfinement
phase, we investigate spatial boundary-condition dependence of the energy of
c\bar c systems above T_c. In fact, for low-lying S-wave c \bar c scattering
states, it is expected that there appears a significant energy difference
\Delta E \equiv E{\rm (APBC)}-E{\rm (PBC)}\simeq2\sqrt{m_c^2+3\pi^2/L^2}-2m_c
(m_c: charm quark mass) between periodic and anti-periodic boundary conditions
on the finite-volume lattice. In contrast, for compact charmonia, there is no
significant energy difference between periodic and anti-periodic boundary
conditions. As a lattice QCD result, almost no spatial boundary-condition
dependence is observed for the energy of the c\bar c system in J/\Psi and
\eta_c channels for T\simeq(1.11-2.07)T_c. This fact indicates that J/\Psi and
\eta_c would survive as spatially compact c\bar c (quasi-)bound states below
2T_c. We also investigate a -wave channel at high temperature with maximally
entropy method (MEM) and find no low-lying peak structure corresponding to
\chi_{c1} at 1.62T_c.Comment: 13 pages, 11 figure
On Witten multiple zeta-functions associated with semisimple Lie algebras IV
In our previous work, we established the theory of multi-variable Witten
zeta-functions, which are called the zeta-functions of root systems. We have
already considered the cases of types , , , and . In
this paper, we consider the case of -type. We define certain analogues of
Bernoulli polynomials of -type and study the generating functions of them
to determine the coefficients of Witten's volume formulas of -type. Next
we consider the meromorphic continuation of the zeta-function of -type and
determine its possible singularities. Finally, by using our previous method, we
give explicit functional relations for them which include Witten's volume
formulas.Comment: 22 pag
Bi-maximal mixing at GUT, the low energy data and the leptogenesis
In the framework of the minimum supersymmetric model with right-handed
neutrinos, we consider the Bi-maximal mixing which is realized at the GUT scale
and discuss a question that this model can reproduce the low energy phenomena
and the leptogenesis.Comment: Talk given by E. Takasugi at NuFact04, Osaka, Japan, July 26 - August
1,2004 - 3 pages, 4 figure
Spitzer Observations of the North Ecliptic Pole
We present a photometric catalog for Spitzer Space Telescope warm mission
observations of the North Ecliptic Pole (NEP; centered at , ). The observations are
conducted with IRAC in 3.6 m and 4.5 m bands over an area of 7.04
deg reaching 1 depths of 1.29 Jy and 0.79 Jy in the 3.6
m and 4.5 m bands respectively. The photometric catalog contains
380,858 sources with 3.6 m and 4.5 m band photometry over the
full-depth NEP mosaic. Point source completeness simulations show that the
catalog is 80% complete down to 19.7 AB. The accompanying catalog can be
utilized in constraining the physical properties of extra-galactic objects,
studying the AGN population, measuring the infrared colors of stellar objects,
and studying the extra-galactic infrared background light.Comment: 10 pages, 11 figures and 3 tables. Accepted to the ApJ
Conversion With Four Generations
We study conversion with sequential four generations. A large mass
for the fourth generation neutrino can enhance the conversion rate by orders of
magnitude. We compare constraints obtained from conversion using
experimental bounds on various nuclei with those from and
. We find that the current bound from conversion
with Au puts the most stringent constraint in this model. The relevant flavor
changing parameter is constrained to
be less than for the fourth generation neutrino mass larger
than 100 GeV. Implications for future conversion,
and experiments are discussed.Comment: Latex 11 pages with 3 figures. An error in figure correcte
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