182 research outputs found
Quantum quench dynamics of the Coulomb Luttinger model
We study the non-equilibrium dynamics of the Luttinger model after suddenly
turning on and off the bare Coulomb interaction between the fermions. We
analyze several correlation functions such as the one particle density matrix
and vertex correlations, its finite time dynamics and the stationary state
limit. Correlations exhibit a non-linear light cone effect: the spreading of
the initial signal accelerates as a consequence of the quantum nature of the
excitations, whose peculiar dispersion of plasmonic type in 1D gives rise to a
logarithmic divergence in the group velocity at . In addition we show that
both the static and dynamic stationary state correlations can be reproduced
with a simple generalised Gibbs ensemble despite the long-range character of
the interactions which precludes the application of the Lieb-Robinson bounds.
We propose a suitable experimental setup in which these effect can be observed
based on ultracold ions loaded on linear traps.Comment: 13 pages, 7 figure
Equations of Motion for the Out-of-Equilibrium Dynamics of Isolated Quantum Systems from the Projection Operator Technique
We present a rigorous framework to obtain evolution equations for the
momentum distribution and higher order correlation functions in weakly
interacting systems based on the Projection Operator Technique. These equations
can be numerically solved in an efficient way. We compare the solution of the
equations with known results for 1D models and find an excellent agreement.Comment: 6 pages, 1 figure, added brief discussion about the validity of the
approximation
The flare origin of Forbush decreases not associated with solar flares on the visible hemisphere of the Sun
Investigations have shown that Forbush decreases (Fds) are produced by the propagation into the interplanetary space of a strong perturbation originating from a solar flare (Sf) accompanied by Type IV radioemission. As the front of the perturbation propagates into the interplanetary space, the region in which the galactic cosmic rays are modulated (Fd-modulated region) rotates westward with the Sun and is generally included between two boundary streams; therefore the Fds not associated with observed type IV Sfs (N.Ass.Fds) are likely to be produced by type IV Sfs occurred on the Sun's backside: these vents can be observed when the Earth crosses the corotating Western boundary of the modulated region
Anomalous short-term increases in the galactic cosmic ray intensity: Are they related to the interplanetary magnetic cloud-like structures?
Thirty-one short-term increases (time duration 24 hours and amplitude up to 5%) in the galactic cosmic ray intensity, occurring inside Forbush decreases events, have been identified over the period 1966 - 1977. These increases are highly anisotropic and occur after the compression region following the shock; the interplanetary medium is characterized by intense ( 10 nT) and higly fluctuating magnetic field B, high velocity, low density and temperature (flare ejecta piston?). These B-fluctuations seem to be ordered variations which could be representative of magnetic clouds. Also the large cosmic ray increase occurring on 17-18 September 1979, belongs to this category of events
Correlative analyses for Homestake neutrino data
We present results from linear correlative analyses between Homestake data and several solar-activity parameters in the period 1970-1992. Our findings support the hypothesis that the observed neutrino flux exhibits a significative correlation with some solar-activity parameters, particularly with those related with the heliomagnetic
field
Longitudinal dependence of the interplanetary perturbation produced by energetic type 4 solar flares and of the associated cosmic ray modulation
One of the most significant features of the flare-associated Forbush decreases (Fds) in the galatctic cosmic ray (c.r.) is the so-called East-West asymmetry: the solar flares (Sfs) observed in the Eastern or central region of the solar disk exhibit a higher probability to cause large Fds than the Sfs occurring in the Western portion of the disk. In particular the interplanetary perturbations generated by Type IV Sfs depress the c.r. intensity in a vast spiral cone-like region (modulated region) which extends along the interplanetary magnetic field from the neighborhood of the active region to the advancing perturbation, and that, immediately after the flare-generated perturbation, the maximum c.r. modulation is observed between 0 and 40 deg. W of the meridian plane crossings the flare site at time of flare (flare's meridian plane)
Suggestions for improving the efficiency of ground-based neutron monitors for detecting solar neutrons
On the occasion of the June 3, 1982 intense gamma-ray solar flare a significant increase in counting rate due to solar neutrons was observed by the neutron monitors of Junsfraujoch and Lomnicky Stit located at middle latitudes and high altitudes. In spite of a larger detector employed and of the smaller solar zenith angle, the amplitude of the same event observed at Rome was much smaller and the statistical fluctuations of the salactic cosmic ray background higher than the ones registered at the two mountain stations, because of the greater atmospheric depth at which the Rome monitor is located. The effeciency for detecting a solar neutron event by a NM-64 monitor as a function of the Sun zenith angle, atmospheric depth and threshold rigidity of the station was studied
Competition between Vortex Unbinding and Tunneling in an Optical Lattice
We study a system of two-dimensional Bose gases trapped in minima of a deep
one-dimensional optical lattice potential. Increasing the tunneling amplitude
between adjacent gases drives a deconfinement transition to a phase where
coherence is established between neighboring two-dimensional gases. We compute
the signature of this transition in the interference pattern of the system as
well as in its rotational response, which provides a direct measurement of the
superfluidity in the system.Comment: 4+ pages, 1 figur
Improved harmonic approximation and the 2D Ising model at and
We propose a new method to determine the unknown parameter associated to a
self-consistent harmonic approximation. We check the validity of our technique
in the context of the sine-Gordon model. As a non trivial application we
consider the scaling regime of the 2D Ising model away from the critical point
and in the presence of a magnetic field . We derive an expression that
relates the approximate correlation length , and .Comment: 11 pages, Latex, 3 figures. Accepted for publication in Journal of
Physics
- …