13 research outputs found
Energy averages and fluctuations in the decay out of superdeformed bands
We derive analytic formulae for the energy average (including the energy
average of the fluctuation contribution) and variance of the intraband decay
intensity of a superdeformed band. Our results may be expressed in terms of
three dimensionless variables: , ,
and . Here is
the spreading width for the mixing of a superdeformed (SD) state with the
normally deformed (ND) states whose spin is the same as 's. The
have mean level spacing and mean electromagnetic decay width
whilst has electromagnetic decay width .
The average decay intensity may be expressed solely in terms of the variables
and or, analogously to statistical
nuclear reaction theory, in terms of the transmission coefficients and
describing transmission from the to the SD band via and
to lower ND states.
The variance of the decay intensity, in analogy with Ericson's theory of
cross section fluctuations depends on an additional variable, the correlation
length
\Gamma_N/(\Gamma_S+\Gamma^{\downarrow})=\frac{d}{2\pi}T_N/(\Gamma_S+\Gamma^{\d
ownarrow}). This suggests that analysis of an experimentally obtained variance
could yield the mean level spacing as does analysis of the cross section
autocorrelation function in compound nuclear reactions.
We compare our results with those of Gu and Weidenm\"uller.Comment: revtex4, 14 pages, 4 figures, to appear in Physical Review
Instantons and Condensate
We argue that the is similar to .Comment: 6 pages, 1 fig., 1 tab., RevTeX to be use
Non-Commutativity of the Zero Chemical Potential Limit and the Thermodynamic Limit in Finite Density Systems
Monte Carlo simulations of finite density systems are often plagued by the
complex action problem. We point out that there exists certain
non-commutativity in the zero chemical potential limit and the thermodynamic
limit when one tries to study such systems by reweighting techniques. This is
demonstrated by explicit calculations in a Random Matrix Theory, which is
thought to be a simple qualitative model for finite density QCD. The
factorization method allows us to understand how the non-commutativity, which
appears at the intermediate steps, cancels in the end results for physical
observables.Comment: 7 pages, 9 figure
Concerning the quark condensate
A continuum expression for the trace of the massive dressed-quark propagator
is used to explicate a connection between the infrared limit of the QCD Dirac
operator's spectrum and the quark condensate appearing in the operator product
expansion, and the connection is verified via comparison with a lattice-QCD
simulation. The pseudoscalar vacuum polarisation provides a good approximation
to the condensate over a larger range of current-quark masses.Comment: 7 pages, LaTeX2e, revtex
The Spectrum of the Dirac Operator in the Linear Sigma Model with Quarks
We derive the spectrum of the Dirac operator for the linear sigma-model with
quarks in the large N_c approximation using renormalization group flow
equations. For small eigenvalues, the Banks-Casher relation and the vanishing
linear term are recovered. We calculate the coefficient of the next to leading
term and investigate the spectrum beyond the low energy regime.Comment: 15 pages, 6 figures, to appear in Phys. Rev.
Chaos Driven Decay of Nuclear Giant Resonances: Route to Quantum Self-Organization
The influence of background states with increasing level of complexity on the
strength distribution of the isoscalar and isovector giant quadrupole resonance
in Ca is studied. It is found that the background characteristics,
typical for chaotic systems, strongly affects the fluctuation properties of the
strength distribution. In particular, the small components of the wave function
obey a scaling law analogous to self-organized systems at the critical state.
This appears to be consistent with the Porter-Thomas distribution of the
transition strength.Comment: 14 pages, 4 Figures, Illinois preprint P-93-12-106, Figures available
from the author
Poisson Statistics for the Largest Eigenvalues in Random Matrix Ensemble
The paper studies the spectral properties of large Wigner, band and sample
covariance random matrices with heavy tails of the marginal distributions of
matrix entries.Comment: This is an extended version of my talk at the QMath 9 conference at
Giens, France on September 13-17, 200
Herstel van heide door middel van slow release mineralengift – resultaten van 3 jaar steenmeel-onderzoek.
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