1,327 research outputs found
The production of charm mesons from quark matter at CERN SPS and RHIC
We study the production of charm mesons and other charm baryons from quark
matter at CERN SPS and RHIC energies. Using quark coalescence models as
hadronization mechanism, we predict particle ratios, absolute yields and
transverse momentum spectra.Comment: 4 pages in Latex, 2 PS figure, to be published in the proceedings of
the SQM'2000 Conference, Berkeley, CA, July 20-25, 2000. Submitted to J.
Phys.
Scattering in the PT-symmetric Coulomb potential
Scattering on the -symmetric Coulomb potential is studied along a
U-shaped trajectory circumventing the origin in the complex plane from
below. This trajectory reflects symmetry, sets the appropriate
boundary conditions for bound states and also allows the restoration of the
correct sign of the energy eigenvalues. Scattering states are composed from the
two linearly independent solutions valid for non-integer values of the 2L
parameter, which would correspond to the angular momentum in the usual
Hermitian setting. Transmission and reflection coefficients are written in
closed analytic form and it is shown that similarly to other -symmetric scattering systems the latter exhibit handedness effect.
Bound-state energies are recovered from the poles of the transmission
coefficients.Comment: Journal of Physics A: Mathematical and Theoretical 42 (2009) to
appea
Underlying events in p+p collisions at LHC energies
General properties of hadron production are investigated in proton-proton
collisions at LHC energies. We are interested in the characteristics of hadron
production outside the identified jet cones. We improve earlier definitions and
introduce surrounding rings/belts around the cone of identified jets. In this
way even multiple jet events can be studied in details. We define the
underlying event as collected hadrons from outside jet cones and outside
surrounding belts, and investigate the features of these hadrons. We use a
PYTHIA generated data sample of proton-proton collisions at s = (7 TeV)^2. This
data sample is analysed by our new method and the widely applied CDF method.
Angular correlations and momentum distributions have been studied and the
obtained results are compared and discussed.Comment: 5 pages, 5 figures, to appear in the EPJ Web of Conferences,
Proceedings of the International Workshop on Hot and Cold Baryonic Matter
2010 (Budapest, Hungary, 15-20 August 2010
The Nuclear Modification Factor at Large Rapidities
RHIC data on high- hadron production display strong suppression in a
wide rapidity region, indicating strong induced energy loss for both
transversally and longitudinally traveling partons. We investigate the
interplay of energy loss and rapidity dependence in a perturbative QCD improved
parton model, and estimate the opacity of the produced hot matter in
collisions at energies GeV and 63 GeV at different
rapidity values. Direction-dependent suppression offers the possibility to
study the geometry of the hot matter.Comment: 4 pages, 2 figures, Contribution to the Poster Proceedings of the
Quark Matter 2005 Conference. To be published in Nuclear Physics
Unified treatment of the Coulomb and harmonic oscillator potentials in dimensions
Quantum mechanical models and practical calculations often rely on some
exactly solvable models like the Coulomb and the harmonic oscillator
potentials. The dimensional generalized Coulomb potential contains these
potentials as limiting cases, thus it establishes a continuous link between the
Coulomb and harmonic oscillator potentials in various dimensions. We present
results which are necessary for the utilization of this potential as a model
and practical reference problem for quantum mechanical calculations. We define
a Hilbert space basis, the generalized Coulomb-Sturmian basis, and calculate
the Green's operator on this basis and also present an SU(1,1) algebra
associated with it. We formulate the problem for the one-dimensional case too,
and point out that the complications arising due to the singularity of the
one-dimensional Coulomb problem can be avoided with the use of the generalized
Coulomb potential.Comment: 18 pages, 3 ps figures, revte
Reflectionless PT-symmetric potentials in the one-dimensional Dirac equation
We study the one-dimensional Dirac equation with local PT-symmetric
potentials whose discrete eigenfunctions and continuum asymptotic
eigenfunctions are eigenfunctions of the PT operator, too: on these conditions
the bound-state spectra are real and the potentials are reflectionless and
conserve unitarity in the scattering process. Absence of reflection makes it
meaningful to consider also PT-symmetric potentials that do not vanish
asymptotically.Comment: 24 pages, to appear in J. Phys. A : Math. Theor; one acknowledgement
and one reference adde
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