2,517,660 research outputs found
Simultaneous Softening of sigma and rho Mesons associated with Chiral Restoration
Complex poles of the unitarized pi-pi scattering amplitude in nuclear matter
are studied. Partial restoration of chiral symmetry is modeled by the decrease
of in-medium pion decay constant f*_{pi}.
For large chiral restoration (f*_{pi}/f_{pi} << 1),
2nd sheet poles in the scalar (sigma) and the vector (rho) mesons are both
dictated by the Lambert W function and show universal softening as f*_{pi}
decreases.
In-medium pi-pi cross section receives substantial contribution from the soft
mode and exhibits a large enhancement in low-energy region.
Fate of this universality for small chiral restoration (f*_{pi}/f_{pi} ~ 1)
is also discussed.Comment: 5 pages, 4-eps figures, version accepted by Phys. Rev. C (R) with
minor modification
Analysis of the vector form factors and with light-cone QCD sum rules
In this article, we calculate the vector form factors and
within the framework of the light-cone QCD sum rules
approach. The numerical values of the are compatible with the
existing theoretical calculations, the central value of the ,
, is in excellent agreement with the values from the chiral
perturbation theory and lattice QCD. The values of the are
very large comparing with the theoretical calculations and experimental data,
and can not give any reliable predictions. At large momentum transfers with
, the form factors and can
either take up the asymptotic behavior of or decrease more
quickly than , more experimental data are needed to select the
ideal sum rules.Comment: 22 pages, 16 figures, revised version, to appear in Eur. Phys. J.
Conductors and newforms for U(1,1)
Let be a non-Archimedean local field whose residue characteristic is odd.
In this paper we develop a theory of newforms for , building on
previous work on . This theory is analogous to the results of
Casselman for and Jacquet, Piatetski-Shapiro, and Shalika for
. To a representation of , we attach an integer
called the conductor of , which depends only on the -packet
containing . A newform is a vector in which is essentially
fixed by a congruence subgroup of level . We show that our newforms are
always test vectors for some standard Whittaker functionals, and, in doing so,
we give various explicit formulae for newforms.Comment: 25 page
A log-free zero-density estimate and small gaps in coefficients of -functions
Let be the Rankin--Selberg -function attached
to automorphic representations and . Let and
denote the contragredient representations associated to
and . Under the assumption of certain upper bounds for
coefficients of the logarithmic derivatives of and
, we prove a log-free zero-density
estimate for which generalises a result due to
Fogels in the context of Dirichlet -functions. We then employ this log-free
estimate in studying the distribution of the Fourier coefficients of an
automorphic representation . As an application we examine the
non-lacunarity of the Fourier coefficients of a modular newform
of weight , level ,
and character . More precisely for and a prime , set
, where We prove that for some
- …