3,461 research outputs found
Dilepton asymmetries at factories in search of transitions
In order to detect the possible presence of
amplitudes in neutral meson decays, we consider the measurement of decay
time asymmetries involving like-sign dilepton events at the factories.Comment: 5 pages, latex, no fig
Carrier relaxation due to electron-electron interaction in coupled double quantum well structures
We calculate the electron-electron interaction induced energy-dependent
inelastic carrier relaxation rate in doped semiconductor coupled double quantum
well nanostructures within the two subband approximation at zero temperature.
In particular, we calculate, using many-body theory, the imaginary part of the
full self-energy matrix by expanding in the dynamically RPA screened Coulomb
interaction, obtaining the intrasubband and intersubband electron relaxation
rates in the ground and excited subbands as a function of electron energy. We
separate out the single particle and the collective excitation contributions,
and comment on the effects of structural asymmetry in the quantum well on the
relaxation rate. Effects of dynamical screening and Fermi statistics are
automatically included in our many body formalism rather than being
incorporated in an ad-hoc manner as one must do in the Boltzman theory.Comment: 26 pages, 5 figure
Method of characteristics and solution of DGLAP evolution equation in leading order (LO) and next to leading order (NLO) at small-x
In this paper the singlet and non-singlet structure functions have been
obtained by solving Dokshitzer, Gribove, Lipatov, Alterelli, Parisi (DGLAP)
evolution equations in leading order (LO) and next to leading order (NLO) at
the small x limit. Here we have used a Taylor Series expansion and then the
method of characteristics to solve the evolution equations. We have also
calculated t and x-evolutions of deuteron structure function and the results
are compared with the New Muon Collaboration (NMC) data.Comment: 16 pages including 7 figure
Dissipationless transport in low density bilayer systems
In a bilayer electronic system the layer index may be viewed as the
z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was
observed in quantum Hall systems and is predicted to exist at zero magnetic
field at low density. This phase is a superfluid for opposite currents in the
two layers. At B=0 the system is gapless but superfluidity is not destroyed by
weak disorder. In the quantum Hall case, weak disorder generates a random gauge
field which probably does not destroy superfluidity. Experimental signatures
include Coulomb drag and collective mode measurements.Comment: 4 pages, no figures, submitted to Phys. Rev. Let
Regge behaviour of distribution functions and t and x-evolutions of gluon distribution function at low-x
In this paper t and x-evolutions of gluon distribution function from
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading
order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this
limit, are presented. We compare our results of gluon distribution function
with MRST 2001, MRST 2004 and GRV '98 parameterizations and show the
compatibility of Regge behaviour of quark and gluon distribution functions with
perturbative quantum chromodynamics(PQCD) at low-x. We also discuss the
limitations of Taylor series expansion method used earlier to solve DGLAP
evolution equations, in the Regge behaviour of distribution functions.Comment: 19 pages, 7 figure
Sub-linear radiation power dependence of photo-excited resistance oscillations in two-dimensional electron systems
We find that the amplitude of the radiation-induced
magnetoresistance oscillations in GaAs/AlGaAs system grows nonlinearly as where is the amplitude and the exponent .
%, with in %the low temperature limit. This striking
result can be explained with the radiation-driven electron orbits model, which
suggests that the amplitude of resistance oscillations depends linearly on the
radiation electric field, and therefore on the square root of the power, .
We also study how this sub-linear power law varies with lattice temperature and
radiation frequency.Comment: 5 pages, 3 figure
Extended Self-similarity in Kinetic Surface Roughening
We show from numerical simulations that a limited mobility solid-on-solid
model of kinetically rough surface growth exhibits extended self-similarity
analogous to that found in fluid turbulence. The range over which
scale-independent power-law behavior is observed is significantly enhanced if
two correlation functions of different order, such as those representing two
different moments of the difference in height between two points, are plotted
against each other. This behavior, found in both one and two dimensions,
suggests that the `relative' exponents may be more fundamental than the
`absolute' ones.Comment: 4 pages, 4 postscript figures included (some changes made according
to referees' comments. accepted for publication in PRE Rapid Communication
- …