6,832 research outputs found
Estimates for parameters and characteristics of the confining SU(3)-gluonic field in an -meson
The confinement mechanism proposed earlier by the author is applied to
estimate the possible parameters of the confining SU(3)-gluonic field in an
-meson. For this aim the electric form factor of an
-meson is nonperturbatively computed in an explicit analytic form.
The estimates obtained are also consistent with the width of the
electromagnetic decay . The corresponding estimates of
the gluon concentrations, electric and magnetic colour field strengths are also
adduced for the mentioned field at the scales of the meson under consideration.Comment: 20 pages, LaTe
Bases in Banach spaces of smooth functions on Cantor-type sets
Cataloged from PDF version of article.We suggest a Schauder basis in Banach spaces of smooth functions and traces of smooth functions on Cantor-type sets. In the construction, local Taylor expansions of functions are used. © 2011 Elsevier Inc
Combined method to extract spectroscopic information
Spectroscopic factors (SF) play an important role in nuclear physics and
astrophysics. The traditional method of extracting SF from direct transfer
reactions suffers from serious ambiguities. We discuss a modified method which
is based on including the asymptotic normalization coefficient (ANC) of the
overlap functions into the transfer analysis. In the modified method the
contribution of the external part of the reaction amplitude, typically
dominant, is fixed and the SF is determined from fitting the internal part. We
illustrate the modified method with reactions on , and targets at different energies. The
modified method allows one to extract the SF, which do not depend on the shape
of the single-particle nucleon-target interaction, and has the potential of
improving the reliability and accuracy of the structure information. This is
specially important for nuclei on dripline, where not much is known.Comment: accepted in Phys. Rev. C, 4 pages and 2 figure
Mahler measure of some n-variable polynomial families
The Mahler measures of some n-variable polynomial families are given in terms
of special values of the Riemann zeta function and a Dirichlet L-series,
generalizing the results of \cite{L}. The technique introduced in this work
also motivates certain identities among Bernoulli numbers and symmetric
functions
Mahler measures and computations with regulators
In this work we apply the techniques that were developed in [Lalin: An
algebraic integration for Mahler measure] in order to study several examples of
multivariable polynomials whose Mahler measure is expressed in terms of special
values of the Riemann zeta function or Dirichlet L-series. The examples may be
understood in terms of evaluations of regulators. Moreover, we apply the same
techniques to the computation of generalized Mahler measures, in the sense of
Gon and Oyanagi [Gon, Oyanagi: Generalized Mahler measures and multiple sine
functions]Comment: 5 figure
Asymptotic normalization coefficients for mirror virtual nucleon decays in a microscopic cluster model
It has been suggested recently (Phys. Rev. Lett. 91, 232501 (2003)) that
charge symmetry of nucleon-nucleon interactions relates the Asymptotic
Normalization Coefficients (ANCs) of proton and neutron virtual decays of
mirror nuclei. This relation is given by a simple analytical formula which
involves proton and neutron separation energies, charges of residual nuclei and
the range of their strong interaction with the last nucleon. Relation between
mirror ANCs, if understood properly, can be used to predict astrophysically
relevant direct proton capture cross sections using neutron ANCs measured with
stable beams. In this work, we calculate one-nucleon ANCs for several light
mirror pairs, using microscopic two-, three- and four-cluster models, and
compare the ratio of mirror ANCs to the predictions of the simple analytic
formula. We also investigate mirror symmetry between other characteristics of
mirror one-nucleon overlap integrals, namely, spectroscopic factors and
single-particle ANCs.Comment: 12 pages, submitted to Phys. Rev.
Symbols of One-Loop Integrals From Mixed Tate Motives
We use a result on mixed Tate motives due to Goncharov
(arXiv:alg-geom/9601021) to show that the symbol of an arbitrary one-loop
2m-gon integral in 2m dimensions may be read off directly from its Feynman
parameterization. The algorithm proceeds via recursion in m seeded by the
well-known box integrals in four dimensions. As a simple application of this
method we write down the symbol of a three-mass hexagon integral in six
dimensions.Comment: 13 pages, v2: minor typos correcte
Benchmark on neutron capture extracted from reactions
Direct neutron capture reactions play an important role in nuclear
astrophysics and applied physics. Since for most unstable short-lived nuclei it
is not possible to measure the cross sections, reactions
have been used as an alternative indirect tool. We analyze simultaneously
at deuteron energies and 56 MeV
and the thermal reaction at 25 meV. We include results for the
ground state and the first excited state of Ca. From the low-energy
reaction, the neutron asymptotic normalization coefficient (ANC) is
determined. Using this ANC, we extract the spectroscopic factor (SF) from the
higher energy data and the data. The SF obtained through
the 56 MeV data are less accurate but consistent with those from the
thermal capture. We show that to have a similar dependence on the single
particle parameters as in the , the (d,p) reaction should be
measured at 30 MeV.Comment: 5 pg, 4 figs, Phys. Rev. C (rapid) in pres
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