1,706 research outputs found
Integral correlation measures for multiparticle physics
We report on a considerable improvement in the technique of measuring
multiparticle correlations via integrals over correlation functions. A
modification of measures used in the characterization of chaotic dynamical
sytems permits fast and flexible calculation of factorial moments and cumulants
as well as their differential versions. Higher order correlation integral
measurements even of large multiplicity events such as encountered in heavy ion
collisons are now feasible. The change from ``ordinary'' to ``factorial''
powers may have important consequences in other fields such as the study of
galaxy correlations and Bose-Einstein interferometry.Comment: 23 pages, 6 tar-compressed uuencoded PostScript figures appended,
preprint TPR-92-4
Bose-Einstein source of intermittency in hadronic interactions
The multi-particle Bose-Einstein correlations are the source of
''intermittency'' in high energy hadronic collisions. The power-law like
increase of factorial moments with decreasing bin size was obtained by complete
event weighing technique with gaussian approximation of space-time particle
emitting source shape. The value of source size parameter was found to be
higher than the common one fitted with the help of the standard Handbury
Brown-Twiss procedure.Comment: 12
Soft-core meson-baryon interactions. II. and scattering
The potential includes the t-channel exchanges of the scalar-mesons
and f_0, vector-meson , tensor-mesons f_2 and f_2' and the
Pomeron as well as the s- and u-channel exchanges of the nucleon N and the
resonances , Roper and S_{11}. These resonances are not generated
dynamically. We consider them as, at least partially, genuine three-quark
states and we treat them in the same way as the nucleon. The latter two
resonances were needed to find the proper behavior of the phase shifts at
higher energies in the corresponding partial waves. The soft-core -model
gives an excellent fit to the empirical S- and P-wave phase shifts up
to T_{lab}=600 MeV. Also the scattering lengths have been reproduced well and
the soft-pion theorems for low-energy scattering are satisfied. The
soft-core model for the interaction is an SU_f(3)-extension of the
soft-core -model. The potential includes the t-channel exchanges
of the scalar-mesons a_0, and f_0, vector-mesons , and
, tensor-mesons a_2, f_2 and f_2' and the Pomeron as well as u-channel
exchanges of the hyperons and . The fit to the empirical S-, P- and D-wave phase shifts up to T_{lab}=600 MeV is reasonable and
certainly reflects the present state of the art. Since the various
phase shift analyses are not very consistent, also scattering observables are
compared with the soft-core -model. A good agreement for the total and
differential cross sections as well as the polarizations is found.Comment: 24 pages, 20 PostScript figures, revtex4, submitted to Phys. Rev.
Studies of multiplicity in relativistic heavy-ion collisions
In this talk I'll review the present status of charged particle multiplicity
measurements from heavy-ion collisions. The characteristic features of
multiplicity distributions obtained in Au+Au collisions will be discussed in
terms of collision centrality and energy and compared to those of p+p
collisions. Multiplicity measurements of d+Au collisions at 200 GeV
nucleon-nucleon center-of-mass energy will also be discussed. The results will
be compared to various theoretical models and simple scaling properties of the
data will be identified.Comment: "Focus on Multiplicity" Internationsl Workshop on Particle
Multiplicity in Relativistic Heavy Ion Collisions, Bari, Italy, June 17-19,
2003, 16 pages, 15 figure
Criticality, Fractality and Intermittency in Strong Interactions
Assuming a second-order phase transition for the hadronization process, we
attempt to associate intermittency patterns in high-energy hadronic collisions
to fractal structures in configuration space and corresponding intermittency
indices to the isothermal critical exponent at the transition temperature. In
this approach, the most general multidimensional intermittency pattern,
associated to a second-order phase transition of the strongly interacting
system, is determined, and its relevance to present and future experiments is
discussed.Comment: 15 pages + 2 figures (available on request), CERN-TH.6990/93,
UA/NPPS-5-9
Random and Correlated Phases of Primordial Gravitaional Waves
The phases of primordial gravity waves is analysed in detail within a quantum
mechanical context following the formalism developed by Grishchuk and Sidorov.
It is found that for physically relevant wavelengths both the phase of each
individual mode and the phase {\it difference} between modes are randomly
distributed. The phase {\it sum} between modes with oppositely directed
wave-vectors, however, is not random and takes on a definite value with no rms
fluctuation. The conventional point of view that primordial gravity waves
appear after inflation as a classical, random stochastic background is also
addressed.Comment: 14 pages, written in REVTE
New model for system of mesoscopic Josephson contacts
Quantum fluctuations of the phases of the order parameter in 2D arrays of
mesoscopic Josephson junctions and their effect on the destruction of
superconductivity in the system are investigated by means of a quantum-cosine
model that is free of the incorrect application of the phase operator. The
proposed model employs trigonometric phase operators and makes it possible to
study arrays of small superconducting granules, pores filled with superfluid
helium, or Josephson junctions in which the average number of particles
(effective bosons, He atoms, and so on) is small, and the standard approach
employing the phase operator and the particle number operator as conjugate ones
is inapplicable. There is a large difference in the phase diagrams between
arrays of macroscopic and mesoscopic objects for and ( is
the characteristic interaction energy of the particle per granule and is
the Josephson coupling constant). Reentrant superconductivity phenomena are
discussed.Comment: 4 pages, 3 Postscript figure
Effect of photoperiod and host distribution on the horizontal transmission of Isaria fumosorosea (Hypocreales: Cordycipitaceae) in greenhouse whitefly assessed using a novel model bioassay
A model bioassay was used to evaluate the epizootic potential and determine the horizontal transmission efficiency of Isaria fumosorosea Trinidadian strains against Trialeurodes vaporariorum pharate adults under optimum conditions (25±0.5°C, ~100% RH) at two different photoperiods. Untreated pharate adults were arranged on laminated graph paper at different distributions to simulate varying infestation levels on a leaf surface. Four potential hosts were located 7, 14 and 21 mm away from a central sporulating cadaver simulating high, medium and low infestation levels, respectively. Percent hosts colonized were recorded 7, 12, 14 and 21 days post-treatment during a 16- and 24-h photophase. After 21 days, mean percent hosts colonized at the highest, middle and lowest infestation levels were 93 and 100%, 22 and 58%, 25 and 39% under a 16- and 24-h photophase, respectively. From the results, it was concluded that the longer the photophase, the greater the percentage of hosts colonized, and as host distance increased from the central sporulating cadaver, colonization decreased. The use of this novel model bioassay technique is the first attempt to evaluate the epizootic potential and determine the horizontal transmission efficiency of I. fumosorosea Trinidadian strains under optimal environmental conditions at different photoperiods. This bioassay can be used to assess horizontal transmission efficiency for the selection of fungi being considered for commercial biopesticide development
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/
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