281 research outputs found
Probing finite size effects in MonteCarlo calculations
The Constrained Effective Potential (CEP) is known to be equivalent to the
usual Effective Potential (EP) in the infinite volume limit. We have carried
out MonteCarlo calculations based on the two different definitions to get
informations on finite size effects. We also compared these calculations with
those based on an Improved CEP (ICEP) which takes into account the finite size
of the lattice. It turns out that ICEP actually reduces the finite size effects
which are more visible near the vanishing of the external source.Comment: LATTICE98(Gauge, Higgs and Yukawa Models
Mass Determination from Constraint Effective Potential
The Constraint Effective Potential (CEP) allows a determination of the mass
and other quantities directly, without relying upon asymptotic correlator
decays. We report and discuss the results of some mass calculations in
, obtained from CEP and our improved version of CEP (ICEP).Comment: LATTICE99(Higgs, Yukawa, SUSY
A Geometrical Interpretation of Hyperscaling Breaking in the Ising Model
In random percolation one finds that the mean field regime above the upper
critical dimension can simply be explained through the coexistence of infinite
percolating clusters at the critical point. Because of the mapping between
percolation and critical behaviour in the Ising model, one might check whether
the breakdown of hyperscaling in the Ising model can also be intepreted as due
to an infinite multiplicity of percolating Fortuin-Kasteleyn clusters at the
critical temperature T_c. Preliminary results suggest that the scenario is much
more involved than expected due to the fact that the percolation variables
behave differently on the two sides of T_c.Comment: Lattice2002(spin
A lattice test of alternative interpretations of ``triviality'' in theory
There are two physically different interpretations of ``triviality'' in
theories. The conventional description predicts a
second-order phase transition and that the Higgs mass must vanish in the
continuum limit if , the physical v.e.v, is held fixed. An alternative
interpretation, based on the effective potential obtained in
``triviality-compatible'' approximations (in which the shifted `Higgs' field
is governed by an effective quadratic Hamiltonian)
predicts a phase transition that is very weakly first-order and that and
are both finite, cutoff-independent quantities. To test these two
alternatives, we have numerically computed the effective potential on the
lattice. Three different methods were used to determine the critical bare mass
for the chosen bare coupling value. All give excellent agreement with the
literature value. Two different methods for obtaining the effective potential
were used, as a control on the results. Our lattice data are fitted very well
by the predictions of the unconventional picture, but poorly by the
conventional picture.Comment: 16 pages, LaTeX, 2 eps figures (acknowledgements added in the
replaced version
Crowded space: a review on radar measurements for space debris monitoring and tracking
Space debris monitoring is nowadays a priority for worldwide space agencies, due to the serious threat that these objects present. More and more efforts have been made to extend the network of available radar systems devoted to the control of space. A meticulous review has been done in this paper, in order to find and classify the considerable amounts of data provided by the scientific community that deal with RADAR measurement for the debris monitoring and tracking. The information gathered is organized based on the volume of found data and classified taking into account the geographical location of the facilities
Comment on "Feynman Effective Classical Potential in the Schrodinger Formulation"
We comment on the paper "Feynman Effective Classical Potential in the
Schrodinger Formulation"[Phys. Rev. Lett. 81, 3303 (1998)]. We show that the
results in this paper about the time evolution of a wave packet in a double
well potential can be properly explained by resorting to a variational
principle for the effective action. A way to improve on these results is also
discussed.Comment: 1 page, 2eps figures, Revte
Microsoft Room Temperature Integrated Terahertz Emitters Based on Three-Wave Mixing in Semiconductor Microcylinders
The 16 November 2006 flank collapse of South-East Crater at Mount Etna, Italy: study of the deposit and hazard assessment
On 16 November 2006 a flank collapse affected the unstable Eastern slope of the South-East Crater
16 (SEC) of Mt. Etna. The collapse occurred during one of the paroxysmal events with sustained strombolian
17 activity that characterized the August-December 2006 eruption and was triggered by erosion of loose,
18 hydrothermally-altered material of the steep south-east sector of SEC from the outpour of lava. The collapse
19 produced a debris avalanche that involved both lithic and juvenile material and resulted in a deposit
20 emplaced on the Eastern flank of the volcano up to 1.2 km away from the source. The total volume of the
21 deposit was estimated to be in the order of 330,000-413,000 m3. The reconstruction of the collapse event
22 was simulated using TITAN2D, software designed to model granular avalanches and landslides. This
23 approach can be used to estimate areas that may be affected by similar collapse events in the future. The
24 area affected by the 16 November 2006 lateral collapse of SEC was a small portion of the Mt. Etna summit
25 area, but the fact that no one was killed or injured should be considered fortuitous. The summit and adjacent
26 areas of the volcano, in fact, are usually visited by many tourists who are not prepared to face this type of
27 danger. The 16 November 2006 collapse points to the need to be prepared for similar events through
28 scientific investigation (analysis of flank instability, numerical simulation of flows) and development of specific
civil protection plans
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