470 research outputs found
A theorem relating a certain generalized Weyl fractional integral with the Laplace transform and a class of Whittaker transforms
AbstractIn the present paper the authors prove a theorem which asserts an interesting relationship between the classical Laplace transform, a certain class of Whittaker transforms, and a Weyl fractional integral involving a general class of polynomials with essentially arbitrary coefficients. By specializing the various parameters involved, this general theorem would readily yield several (known or new) results involving simpler integral operators. It is also shown how the relationship asserted by the theorem can be applied to evaluate the generalized Weyl fractional integrals of various special functions
Dynamical Properties of Heavy-Ion Collisions from the Photon-Photon Intensity Correlations
We consider here the bremsstrahlung emission of photons at low and
intermediate energies of the projectile. and derive
expressions more general than previous results obtained by Neuhauser which were
limited to the case of isotropic systems. We find that the two-photon
correlation function strongly depends not only on the space-time properties of
the collision region but also on the dynamics of the proton-neutron scattering
process in nuclear matter. As a consequence of polarisation correlations it
turns out that for a purely chaotic source the intercept of the correlation
function of photons can reach the value (as compared with the maximum value
for isotropic systems). Furthermore even for ``hard" photons () the maximum of the correlation function can reach the value of in
contrast with the value of derived by Neuhauser for this case. The
formulae obtained in this paper which include also the possible presence of a
coherent component can be used as a basis for a systematic analysis of photon
intensity-interferometry experiments.Comment: 12 pages, LaTeX, DMR-THEP-93-2/
Infrared gluons, intrinsic transverse momentum and rising total cross-sections
We discuss the infrared limit for soft gluon kt-resummation and relate it to
physical observables such as the intrinsic transverse momentum and the high
energy limit of total cross-sections.Comment: 8 pages, 6 figures, Presented at Hadron Structure '09, Tatranska
Strba, September 2009, Slovacchia, to be published in the Conference
Proceeding
Thermal photon production in heavy ion collisions
Using a three-dimensional hydrodynamic simulation of the collision and an
equation of state containing a first order phase transition to the quark-gluon
plasma, we study thermal photon production for collisions at
AGeV and for collisions at AGeV. We obtain
surprisingly high rates of thermal photons even at the lower energy, suggesting
that, contrary to what was expected so far, photon production may be an
interesting topic for experimental search also at the Alternating Gradient
Synchrotron. When applied to the reaction at AGeV, our model can
reproduce preliminary data obtained by the WA80 Collaboration without having to
postulate the existence of an extremely long-lived mixed phase as was recently
proposed.Comment: 9 pages, figures are uudecoded compressed and tare
Bounds for Bose-Einstein Correlation Functions
Bounds for the correlation functions of identical bosons are discussed for
the general case of a Gaussian density matrix. In particular, for a purely
chaotic system the two-particle correlation function must always be greater
than one. On the other hand, in the presence of a coherent component the
correlation function may take values below unity. The experimental situation is
briefly discussed.Comment: 7 pages, LaTeX, DMR-THEP-93-5/
Hydrodynamical analysis of single inclusive spectra and Bose-Einstein correlations for at 160 AGeV
We present the first analysis of preliminary data for at 160
using 3+1-dimensional relativistic hydrodynamics. We find excellent agreement
with the rapidity spectra of negative hadrons and the correlation measurements.
The data indicates a large amount of stopping; of the invariant energy
of the collision is thermalized and of the baryons are contained in the
central fireball. Within our model this implies that a quark-gluon-plasma of
lifetime 3.4 was formed.Comment: 13 pages, 5 Postscript figures (attached to this file as compressed
and uuencoded Postscript file
Photon Total Cross-sections
We discuss present predictions for the total and
cross-sections, highlighting why predictions differ. We present results from
the Eikonal Minijet Model and improved predictions based on soft gluon
resummation.Comment: 7 pages, 10 figures, LaTeX, requires espcrc2.sty, Talk presented by
G. Pancheri at PHOTON-2003, International Meeting on Structure and
Interactions of the Photon, Frascati, Italy, April 7-11, 200
Deflection of coronal rays by remote CMEs: shock wave or magnetic pressure?
We analyze five events of the interaction of coronal mass ejections (CMEs)
with the remote coronal rays located up to 90^\circ away from the CME as
observed by the SOHO/LASCO C2 coronagraph. Using sequences of SOHO/LASCO C2
images, we estimate the kink propagation in the coronal rays during their
interaction with the corresponding CMEs ranging from 180 to 920 km/s within the
interval of radial distances form 3 R. to 6 R. . We conclude that all studied
events do not correspond to the expected pattern of shock wave propagation in
the corona. Coronal ray deflection can be interpreted as the influence of the
magnetic field of a moving flux rope related to a CME. The motion of a
large-scale flux rope away from the Sun creates changes in the structure of
surrounding field lines, which are similar to the kink propagation along
coronal rays. The retardation of the potential should be taken into account
since the flux rope moves at high speed comparable with the Alfven speed.Comment: Accepted for Publication in Solar Physic
Reanalysis of two eclipsing binaries: EE Aqr and Z Vul
We study the radial-velocity and light curves of the two eclipsing binaries
EE Aqr and Z Vul. Using the latest version of the Wilson & Van Hamme (2003)
model, absolute parameters for the systems are determined. We find that EE Aqr
and Z Vul are near-contact and semi-detached systems, respectively. The primary
component of EE Aqr fills about 96% of its 'Roche lobe', while its secondary
one appears close to completely filling this limiting volume. In a similar way,
we find fill-out proportions of about 72 and 100% of these volumes for the
primary and secondary components of Z Vul respectively. We compare our results
with those of previous authors.Comment: 13 pages, 8 figures, 10 table
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