537,617 research outputs found
Field induced superconductivity with enhanced and tunable paramagnetic limit
We demonstrate that in a superconducting multilayered system with alternating
interlayer coupling a new type of nonuniform superconducting state can be
realized under in-plane magnetic field. The Zeeman effect in this state is
compensated by the energy splitting between bonding and antibonding levels.
Such compensation mechanism at low temperature leads to the field-induced
superconductivity. We discuss the conditions for the experimental observation
of the predicted phenomena.Comment: 5 pages, 4 figures include
QCD Saturation Equations including Dipole-Dipole Correlation
We derive two coupled non-linear evolution equations corresponding to the
truncation of the Balitsky infinite hierarchy of saturation equations after
inclusion of dipole-dipole correlations, i.e. one step beyond the
Balitsky-Kovchegov (BK) equation. We exhibit an exact solution for maximal
correlation which still satisfies the same asymptotic geometric scaling as BK
but with the S-matrix going to 1/2 (instead of 0) in the full saturation
region.Comment: 4 pages, no figure. Comment, references and acknowledgment adde
Fronts in passive scalar turbulence
The evolution of scalar fields transported by turbulent flow is characterized
by the presence of fronts, which rule the small-scale statistics of scalar
fluctuations. With the aid of numerical simulations, it is shown that: isotropy
is not recovered, in the classical sense, at small scales; scaling exponents
are universal with respect to the scalar injection mechanisms; high-order
exponents saturate to a constant value; non-mature fronts dominate the
statistics of intense fluctuations. Results on the statistics inside the
plateaux, where fluctuations are weak, are also presented. Finally, we analyze
the statistics of scalar dissipation and scalar fluxes.Comment: 18 pages, 27 figure
Quantal Two-Centre Coulomb Problem treated by means of the Phase-Integral Method II. Quantization Conditions in the Symmetric Case Expressed in Terms of Complete Elliptic Integrals. Numerical Illustration
The contour integrals, occurring in the arbitrary-order phase-integral
quantization conditions given in a previous paper, are in the first- and
third-order approximations expressed in terms of complete elliptic integrals in
the case that the charges of the Coulomb centres are equal. The evaluation of
the integrals is facilitated by the knowledge of quasiclassical dynamics. The
resulting quantization conditions involving complete elliptic integrals are
solved numerically to obtain the energy eigenvalues and the separation
constants of the and states of the hydrogen molecule ion
for various values of the internuclear distance. The accuracy of the formulas
obtained is illustrated by comparison with available numerically exact results.Comment: 19 pages, RevTeX 4, 4 EPS figures, submitted to J. Math. Phy
-matrix representation of the finite temperature propagator in -QFT
The two-point Green function of the massive scalar -quantum field
theory with interaction at finite temperature is evaluated up
to the 2nd order of perturbation theory. The averaging on the vacuum
fluctuations is separated from the averaging on the thermal fluctuations
explicitly. As a result, the temperature dependent part of the propagator is
expressed through the scattering amplitudes. The obtained expression is
generalized for higher orders of perturbation theory.Comment: 9 page
On passage through resonances in volume-preserving systems
Resonance processes are common phenomena in multiscale (slow-fast) systems.
In the present paper we consider capture into resonance and scattering on
resonance in 3-D volume-preserving slow-fast systems. We propose a general
theory of those processes and apply it to a class of viscous Taylor-Couette
flows between two counter-rotating cylinders. We describe the phenomena during
a single passage through resonance and show that multiple passages lead to the
chaotic advection and mixing. We calculate the width of the mixing domain and
estimate a characteristic time of mixing. We show that the resulting mixing can
be described using a diffusion equation with a diffusion coefficient depending
on the averaged effect of the passages through resonances.Comment: 23 pages and 9 Figure
On radiative damping in plasma-based accelerators
Radiative damping in plasma-based electron accelerators is analyzed. The
electron dynamics under combined influence of the constant accelerating force
and the classical radiation reaction force is studied. It is shown that
electron acceleration cannot be limited by radiation reaction. If initially the
accelerating force was stronger than the radiation reaction force then the
electron acceleration is unlimited. Otherwise the electron is decelerated by
radiative damping up to a certain instant of time and then accelerated without
limits. Regardless of the initial conditions the infinite-time asymptotic
behavior of an electron is governed by self-similar solution providing
unlimited acceleration. The relative energy spread induced by the radiative
damping decreases with time in the infinite-time limit
Mandelstam cuts and light-like Wilson loops in N=4 SUSY
We perform an analytic continuation of the two-loop remainder function for
the six-point planar MHV amplitude in N=4 SUSY, found by Goncharov, Spradlin,
Vergu and Volovich from the light-like Wilson loop representation. The
remainder function is continued into a physical region, where all but two
energy invariants are negative. It turns out to be pure imaginary in the
multi-Regge kinematics, which is in an agreement with the predictions based on
the Steinmann relations for the Regge poles and Mandelstam cut contributions.
The leading term reproduces correctly the expression calculated by one of the
authors in the BFKL approach, while the subleading term presents a result, that
was not yet found with the use of the unitarity techniques. This supports the
applicability of the Wilson loop approach to the planar MHV amplitudes in N=4
SUSY.Comment: 11 pages, 4 figure
The beta-delayed neutron emission in 78Ni region
A systematic study of the total -decay half-lives and -delayed
neutron emission probabilities is performed. The -strength function is
treated within the self-consistent density-functional + continuum-QRPA
framework including the Gamow-Teller and first-forbidden transitions. The
experimental total -decay half-lives for the Ni isotopes with 76
are described satisfactorily. The half-lives predicted from =70 up to =86
reveal fairly regular -behaviour which results from simultaneous account for
the Gamow-Teller and first-forbidden transitions. For 28 nuclei, a
suppression of the delayed neutron emission probability is found when the
=50 neutron closed shell is crossed. The effect originates from the
high-energy first-forbidden transitions to the states outside the -window in the daughter nuclei.
PACS numbers: 23.40.Bw,21.60.Jz,25.30.Pt,26.30.+kComment: LaTeX, 13 pages, 5 figure
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