8,071 research outputs found
Study of the Coleman - de Luccia instanton of the second order
We study the second order Coleman - de Luccia instanton which appears as the
curvature of the effective potential reaches a sufficiently large value. We
show how one can find the approximative formula for this instanton by
perturbative expansion in the case when the second derivative of the effective
potential divided by the Hubble parameter squared is close to -10, and we
perform a numerical study of this instanton in the case of quasi-exponential
potential.Comment: three pages, one figur
Research of problems and technologies for the development scheme of data national standard data transmission for Russian oil & gas companies
Phase diagram and critical properties in the Polyakov--Nambu--Jona-Lasinio model
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio model at finite temperature and nonzero chemical
potential with three quark flavours. Chiral and deconfinement phase transitions
are discussed, and the relevant order-like parameters are analyzed. The results
are compared with simple thermodynamic expectations and lattice data. A special
attention is payed to the critical end point: as the strength of the
flavour-mixing interaction becomes weaker, the critical end point moves to low
temperatures and can even disappear.Comment: Talk given at the 9th International Conference on Quark Confinement
and the Hadron Spectrum - QCHS IX, Madrid, Spain, 30 August - September 201
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.
Smoothness of the Green Function for a Special Domain
Cataloged from PDF version of article.We consider a compact set K ⊂ ℝ in the form of the union of a sequence of segments. By means of nearly Chebyshev polynomials for K, the modulus of continuity of the Green functions gℂ\K is estimated. Markov's constants of the corresponding set are evaluated. © Instytut Matematyczny PAN, 2012
Hawking-Moss Tunneling with a Dirac-Born-Infeld Action
The Hawking-Moss tunneling rate for a field described by the
Dirac-Born-Infeld action is calculated using a stochastic approach. We find
that the effect of the non-trivial kinetic term is to enhance the tunneling
rate, which can be exponentially significant. This result should be compared to
the DBI enhancement found in the Coleman-de Luccia case.Comment: 4 pages, version accepted in Phys. Rev. D., additional references and
example applicatio
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
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