4,340 research outputs found
Omega_{ccc} production via fragmentation at LHC
In the framework of the leading order of perturbative QCD and the
nonrelativistic quark-diquark model of baryons we have obtained fragmentation
function for c-quark to split into Omega_{ccc} baryon. It is shown that at LHC
one can expect 3.5 10^3 events with Omega_{ccc} at p_t>5 GeV/c and -1<y<1 per
year.Comment: LaTex, 5 pages and 2 figures. Talk presented at XIV Workshop on High
Energy Physics and Quantum Field Theory, Moscow, May 27 - June 4, 199
Topology by dissipation
Topological states of fermionic matter can be induced by means of a suitably
engineered dissipative dynamics. Dissipation then does not occur as a
perturbation, but rather as the main resource for many-body dynamics, providing
a targeted cooling into a topological phase starting from an arbitrary initial
state. We explore the concept of topological order in this setting, developing
and applying a general theoretical framework based on the system density matrix
which replaces the wave function appropriate for the discussion of Hamiltonian
ground-state physics. We identify key analogies and differences to the more
conventional Hamiltonian scenario. Differences mainly arise from the fact that
the properties of the spectrum and of the state of the system are not as
tightly related as in a Hamiltonian context. We provide a symmetry-based
topological classification of bulk steady states and identify the classes that
are achievable by means of quasi-local dissipative processes driving into
superfluid paired states. We also explore the fate of the bulk-edge
correspondence in the dissipative setting, and demonstrate the emergence of
Majorana edge modes. We illustrate our findings in one- and two-dimensional
models that are experimentally realistic in the context of cold atoms.Comment: 61 pages, 8 figure
Production of electroweak gauge bosons in off-shell gluon-gluon fusion
We study the production of electroweak gauge bosons at high energies in the
framework of kt-factorization QCD approach. Contributions from the valence
quarks are calculated using the quark-gluon interaction and quark-antiquark
annihilation QCD subprocesses. The total and differential cross sections (as a
function of the transverse momentum and rapidity) are presented and the ratio
of cross sections for W and Z boson production is investigated. The
conservative error analysis is performed. In the numerical calculations two
different sets of unintegrated gluon distributions in the proton are used: the
one obtained from Ciafaloni-Catani-Fiorani-Marchesini evolution equation and
the other from Kimber-Martin-Ryskin prescription. Theoretical results are
compared with experimental data taken by the D0 and CDF collaborations at the
Tevatron. We demonstrate the importance of the quark component in parton
evolution in description of the experimental data. This component is very
significant also at the LHC energies.Comment: 33 pages, 18 figure
Production of Triply Charmed Baryons in Annihilation
The total and differential cross sections for the production of triply
charmed baryons in annihilation are calculated at
the -boson pole.Comment: 13 pages, 2 figure
Prompt photon hadroproduction at high energies in off-shell gluon-gluon fusion
The amplitude for production of a single photon associated with quark pair in
the fusion of two off-shell gluons is calculated. The matrix element found is
applied to the inclusive prompt photon hadroproduction at high energies in the
framework of kt-factorization QCD approach. The total and differential cross
sections are calculated in both central and forward pseudo-rapidity regions.
The conservative error analisys is performed. We used the unintegrated gluon
distributions in a proton which were obtained from the full CCFM evolution
equation as well as from the Kimber-Martin-Ryskin prescription. Theoretical
results were compared with recent experimental data taken by the D0 and CDF
collaborations at Fermilab Tevatron. Theoretical predictions for the LHC
energies are given.Comment: 32 pages, 18 figure
Anisotropic Fermi surfaces and Kohn-Luttinger superconductivity in two dimensions
The instabilities induced on a two-dimensional system of correlated electrons
by the anisotropies of its Fermi line are analyzed on general grounds. Simple
scaling arguments allow to predict the opening of a superconducting gap with a
well-defined symmetry prescribed by the geometry of the Fermi line. The same
arguments predict a critical dimension of 3/2 for the transition of the
two-dimensional system to non-Fermi liquid behavior. The methods are applied to
the t-t' Hubbard model in a wide range of dopings.Comment: 25 pages, 13 postscript figure
Polarizations of J/\psi and \psi' in hadroproduction at Tevatron in the k_t factorization approach
We present a calculation for the polarizations of and
produced in the hadron collisions at the Fermilab Tevatron. Various color octet
channels including , , and as
well as contributions from decays are considered in the
factorization approach. We find that in a rather wide range of the transverse
momenta of and , the production rates could be dominated by the
channel, and the predicted polarizations from the
channel and feeddown contributions are roughly
compatible with the preliminary CDF data. This might provide a possible release
from the conflict between the NRQCD collinear parton model calculations and the
CDF data.Comment: 12 pages, 4 PS files, final version for publicatio
Intrinsic defects in silicon carbide LED as a perspective room temperature single photon source in near infrared
Generation of single photons has been demonstrated in several systems.
However, none of them satisfies all the conditions, e.g. room temperature
functionality, telecom wavelength operation, high efficiency, as required for
practical applications. Here, we report the fabrication of light emitting
diodes (LEDs) based on intrinsic defects in silicon carbide (SiC). To fabricate
our devices we used a standard semiconductor manufacturing technology in
combination with high-energy electron irradiation. The room temperature
electroluminescence (EL) of our LEDs reveals two strong emission bands in
visible and near infrared (NIR), associated with two different intrinsic
defects. As these defects can potentially be generated at a low or even single
defect level, our approach can be used to realize electrically driven single
photon source for quantum telecommunication and information processing
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