587 research outputs found
Center-Edge Asymmetry at Hadron Colliders
We investigate the possibility of using the center-edge asymmetry to
distinguish graviton exchange from other new physics effects at hadron
colliders. Specifically, we study lepton-pair production within the ADD and RS
scenarios. At the Tevatron, the graviton-Z interference is the most important
contribution to the center-edge asymmetry, whereas at the LHC, the dominant
contribution comes from gluon fusion via graviton exchange, which has no
analogue at e^+ e^- colliders. We find that spin-2 and spin-1 exchange can be
distinguished up to an ADD cut-off scale, M_H, of about 5 TeV, at the 95% CL.
In the RS scenario, spin-2 resonances can be identified in most of the favored
parameter space.Comment: 23 pages, including figure
Analysis And Optimization Of Exponential Queueing Networks By Means Of Parallel Calculations
The method of a finding of mean characteristics of an open exponential queueing network (QN) and solution of the problem of coasts optimization in such network by means of parallel calculations is considered. The software for solution of the formulated problems, developed with usage of technology of programming MPI and libraries PETSc is described
Homoclinic standing waves in focussing DNLS equations --Variational approach via constrained optimization
We study focussing discrete nonlinear Schr\"{o}dinger equations and present a
new variational existence proof for homoclinic standing waves (bright
solitons). Our approach relies on the constrained maximization of an energy
functional and provides the existence of two one-parameter families of waves
with unimodal and even profile function for a wide class of nonlinearities.
Finally, we illustrate our results by numerical simulations.Comment: new version with revised introduction and improved condition (A3); 16
pages, several figure
Nearly frozen Coulomb Liquids
We show that very long range repulsive interactions of a generalized
Coulomb-like form , with (-dimensionality),
typically introduce very strong frustration, resulting in extreme fragility of
the charge-ordered state. An \textquotedbl{}almost frozen\textquotedbl{} liquid
then survives in a broad dynamical range above the (very low) melting
temperature which is proportional to . This
\textquotedbl{}pseudogap\textquotedbl{} phase is characterized by unusual
insulating-like, but very weakly temperature dependent transport, similar to
experimental findings in certain low carrier density systems.Comment: 5 pages,4 figure
Signals of Warped Extra Dimensions at the LHC
We discuss the signatures of the spin-2 graviton excitations predicted by the
Randall-Sundrum model with one warped extra dimension, in dilepton and diphoton
production at LHC. By using a specific angular analysis, we assess the ranges
in mass and coupling constant where such gravitons can be discriminated against
competitor spin-1 and spin-0 objects, that potentially could manifest
themselves in these processes with the same mass and rate of events. Depending
on the value of the coupling constant to quarks and leptons, the numerical
results indicate graviton identification mass ranges up to 1.1-2.4 TeV and
1.6-3.2 TeV for LHC nominal energy of 14 TeV and time-integrated luminosity of
10 and 100~, respectively.Comment: 8 pages, Talk given at QCD@Work - International Workshop on QCD -
Theory and Experiment, 20 - 23 June, 2010, Martina Franca Ital
Pecularities of Hall effect in GaAs/{\delta}<Mn>/GaAs/In\timesGa1-\timesAs/GaAs (\times {\approx} 0.2) heterostructures with high Mn content
Transport properties of GaAs/{\delta}/GaAs/In\timesGa1-\timesAs/GaAs
structures containing InxGa1-xAs (\times {\approx} 0.2) quantum well (QW) and
Mn delta layer (DL) with relatively high, about one Mn monolayer (ML) content,
are studied. In these structures DL is separated from QW by GaAs spacer with
the thickness ds = 2-5 nm. All structures possess a dielectric character of
conductivity and demonstrate a maximum in the resistance temperature dependence
Rxx(T) at the temperature {\approx} 46K which is usually associated with the
Curie temperature Tc of ferromagnetic (FM) transition in DL. However, it is
found that the Hall effect concentration of holes pH in QW does not decrease
below TC as one ordinary expects in similar systems. On the contrary, the
dependence pH(T) experiences a minimum at T = 80-100 K depending on the spacer
thickness, then increases at low temperatures more strongly than ds is smaller
and reaches a giant value pH = (1-2)\cdot10^13 cm^(-2). Obtained results are
interpreted in the terms of magnetic proximity effect of DL on QW, leading to
induce spin polarization of the holes in QW. Strong structural and magnetic
disorder in DL and QW, leading to the phase segregation in them is taken into
consideration. The high pH value is explained as a result of compensation of
the positive sign normal Hall effect component by the negative sign anomalous
Hall effect component.Comment: 19 pages, 6 figure
Pulse cathodo- and thermoluminescence of alumina ceramic with manganese
Alumina ceramics with manganese in concentration range 0.001-18 wt. % are synthesized. Luminescent properties of obtained ceramics at temperatures 1500-1700°C of sintering in vacuum are investigated. An increase in the manganese concentration leads to quenching of the pulse cathodoluminescence band at 420 nm and the main dosimetric peak at 460 K. The intensity of luminescence in the 676 nm band at manganese concentrations of more than 1 wt. % and the TL yield for all the observed peaks increase when annealing temperature rises. Sublinear increase in TL intensity with a growing dose is observed in the range of 3-1000 Gy in 460 and 620 K peaks. © Published under licence by IOP Publishing Ltd.The reported study was funded by RFBR according to the research project № 18-33-00085
Quantum spin chains with site dissipation
We use Monte Carlo simulations to study chains of Ising- and XY-spins with
dissipation coupling to the site variables. The phase diagram and critical
exponents of the dissipative Ising chain in a transverse magnetic field have
been computed previously, and here we consider a universal ratio of
susceptibilities. We furthermore present the phase diagram and exponents of the
dissipative XY-chain, which exhibits a second order phase transition. All our
results compare well with the predictions from a dissipative field
theory
Action minimizing fronts in general FPU-type chains
We study atomic chains with nonlinear nearest neighbour interactions and
prove the existence of fronts (heteroclinic travelling waves with constant
asymptotic states). Generalizing recent results of Herrmann and Rademacher we
allow for non-convex interaction potentials and find fronts with non-monotone
profile. These fronts minimize an action integral and can only exists if the
asymptotic states fulfil the macroscopic constraints and if the interaction
potential satisfies a geometric graph condition. Finally, we illustrate our
findings by numerical simulations.Comment: 19 pages, several figure
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