5,539 research outputs found
Phase diagram of two dimensional electron gas in a perpendicular magnetic field around Landau level filling factors \nu=1 and \nu=3
The measured melting curve between the crystal and liquid phases
is analyzed using thermodynamics to extract the change of magnetization as a function of the Landau level filling factor \ near . \ An
explanation of ( is proposed \ in terms of Skyrmions. \ Near
, a Wigner crystal is the most probable solid phase, experiments
excluding Skyrmions.Comment: 5 pages, 4 figure
Stability Conditions and the Single Mode Approximation in FQHE
A thermodynamic stability criterion for the spontaneous breaking of the
translation invariance of many particle systems is derived. It simply requires
the positive character of the wavevector dependent dielectric function as
generalising the same condition for macroscopic dielectric constants. Its
application to the Single Mode Approximation (SMA) for the description of the
collective modes of the filling factor 1/m Laughlin states is considered. The
results indicate that the stability condition is violated by the SMA for all
the relevant states m=3,5,7,9 in a wavevector neighborhood of the magneto-roton
minima. These conclusions are in qualitative agreement with similar results
obtained from the solution of the Bethe-Salpeter equation at 1/3 filling factor
for both composite fermions and phenomenologically described electrons in the
Laughlin state.Comment: 14 pages, two figures, the spelling and acknowledgments were
correcte
Renormalized Wick expansion for a modified PQCD
The renormalization scheme for the Wick expansion of a modified version of
the perturbative QCD introduced in previous works is discussed. Massless QCD is
considered, by implementing the usual multiplicative scaling of the gluon and
quark wave functions and vertices. However, also massive quark and gluon
counter-terms are allowed in this mass less theory since the condensates are
expected to generate masses. A natural set of expansion parameters of the
physical quantities is introduced: the coupling itself and to masses and
associated to quarks and gluons respectively. This procedure allows to
implement a dimensional transmutation effect through these new mass scales. A
general expression for the new generating functional in terms of the mass
parameters and is obtained in terms of integrals over arbitrary but
constant gluon or quark fields in each case. Further, the one loop potential,
is evaluated in more detail in the case when only the quark condensate is
retained. This lowest order result again indicates the dynamical generation of
quark condensates in the vacuum.Comment: 13 pages, one figur
Effect of Laughlin correlations on crystalline mean field solutions of the 2DEG in FQHE regime
The energy per particle of many body wavefunctions that mix Laughlin liquid
with crystalline correlations for periodic samples in the Haldane-Rezayi
configuration is numerically evaluated for periodic samples. The Monte Carlo
algorithm is employed and the wave functions are constructed in such a way that
have the same zeroes as the periodic Laughlin states. Results with up to 16
particles show that these trial wavefunctions have lower energy than the
periodic Laughlin states for finite samples even at . Preliminary
results for 36 particles suggest that this tendency could reach the
thermodynamic limit. These results get relevance in view of the very recent
experimental measures that indicate the presence of periodic structures in the
2DEG for extremely small temperatures and clean samples, inclusive at main FQHE
filling fractions .Comment: 4 pages, 1 figure, 2 table
Perturbative QCD with Quark and Gluon Condensates
QCD perturbation theory using quark and gluon propagators that have an extra
term at zero four-momentum is equivalent to standard PQCD in the presence of
massless quark and gluon pairs in the perturbative vacuum. We verify at low
orders in perturbation theory that and that quarks
acquire a constituent mass. Thus chiral symmetry is spontaneously broken, and
the conservation of the axial vector current ensures a massless pion. The gluon
pairs generate an expectation value and a tachyonic
gluon mass. Lorentz and gauge symmetry is preserved, and the short-distance
structure of PQCD is unaffected. The modified perturbative expansion thus
contains relevant elements of QCD at both short and long distances.Comment: 12 pages, 2 figure
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