73 research outputs found
On the forward-backward correlations in a two-stage scenario
It is demonstrated that in a two-stage scenario with elementary Poissonian
emitters of particles (colour strings) arbitrarily distributed in their number
and average multiplicities, the forward- backward correlations are completely
determined by the final distribution of the forward particles. The observed
linear form of the correlations then necessarily requires this distribution to
have a negative binomial form. For emitters with a negative binomial
distribution of the produced particles distributed so as to give the final
distribution also of a negative binomial form, the forward-backward
correlations have an essentially non-linear form, which disagrees with the
experimental data.Comment: 14 pages in LaTex, 1 figure in Postscrip
Cluster Structure of Disoriented Chiral Condensates in Rapidity Distribution
We study the creation of disoriented chiral condensates with some initial
boundary conditions that may be expected in the relativistic heavy ion
collisions. The equations of motion in the linear -model are solved
numerically with and without a Lorentz-boost invariance. We suggest that a
distinct cluster structure of coherent pion production in the rapidity
distribution may emerge due to a quench and may be observed in experiments.Comment: 10 pages in LaTex, 2 uuencoded ps figures, LBL-3493
Forward-Backward Charge Fluctuations at RHIC Energies
We use the ultra-relativistic quantum molecular dynamic UrQMD version 2.2 to
study forward backward fluctuations and compare our results with the published
data by the PHOBOS.Comment: 4 pages, 6 figures, poster presented at Strong & Electroweak Matter
(SEWM2006), BNL, United States, May 10-13 200
Cosmic Ray Astrophysics and Hadronic Interactions
Research in cosmic rays is now nearly a century old, but most of the
fundamental questions in this field remain unanswered, on the other hand the
perspectives of future studies in the next decade are very bright. New
detectors will provide higher quality data in the entire energy range from 10^8
to 10^{20} eV (or more if particles of higher energy have non negligible
fluxes), moreover cosmic ray astrophysics must now be considered, together with
gamma, neutrino and gravitational wave astronomy, as one of the subfields of
high energy astrophysics, and using information from these four "messengers"
there is the potential of a detailed understanding of the origin of the high
energy radiation in the universe. High energy cosmic rays are measured
indirectly observing the showers they generate in the atmosphere, and a correct
and detailed interpretation of these measurements will require an improved
understanding of the properties of hadronic interactions. The new collider
experiments, and in particular the LHC project at CERN offer the unique
possibility to perform measurements of great value for cosmic ray astrophysics.
It is of great importance for cosmic research that this possibility is fully
exploited with the appropriate instrumentation and analysis.Comment: Summary talk at the XII ISVHECRI (Inernational Symposium on Very High
Energy Cosmic Ray Interactions). 16 pages, 9 figure
Signals of Disoriented Chiral Condensate
If a disoriented chiral condensate is created over an extended space-time
region following a rapid cooling in hadronic or nuclear collisions, the
misalignment of the condensate with the electroweak symmetry breaking can
generate observable effects in the processes which involve both strong and
electromagnetic interactions. We point out the relevance of the dilepton decay
of light vector mesons as a signal for formation of the disoriented condensate.
We predict that the decay \rho^0 to dileptons will be suppressed and/or the
\rho resonance peak widens, while the decay \omega to dileptons will not be
affected by the condensate.Comment: 13 pages in LaTeX, UCB-PTH-94/05, LBL-3533
Leading particle effect, inelasticity and the connection between average multiplicities in {\bf } and {\bf } processes
The Regge-Mueller formalism is used to describe the inclusive spectrum of the
proton in collisions. From such a description the energy dependences of
both average inelasticity and leading proton multiplicity are calculated. These
quantities are then used to establish the connection between the average
charged particle multiplicities measured in {\bf } and {\bf } processes. The description obtained for the leading proton cross section
implies that Feynman scaling is strongly violated only at the extreme values of
, that is at the central region () and at the diffraction
region (), while it is approximately observed in the
intermediate region of the spectrum.Comment: 20 pages, 10 figures, to be published in Physical Review
Some Properties of a Transient New Coherent Condition of Matter Formed in High--Energy Hadronic Collisions
We investigate the dynamical possibility for the formation of a transient new
coherent condition of matter in high--energy hadronic collisions. The coherent
bosonic amplitude is characterized by a non--zero momentum and is sustained by
--wave interactions of quasi--pions in a dense fermionic medium. We make
quantitative estimates of several essential properties: the condensate momentum
and the fermionic density, the size of the coherent amplitude and the negative
energy density contributed by the condensate, a characteristic proper time for
the system to exist prior to breakdown into a few pions, and a characteristic
extension of the system over the plane perpendicular to the collision axis.
These quantities then allow us to make definite estimates of new signals: a few
pions with anomalously small transverse momenta MeV/c; and a
possible anomalous bremsstrahlung of very soft photons with characteristic
transverse momenta as low as about 4 MeV/c.Comment: 23 pages, LaTeX. A complete postscript file is available via
anonymous ftp at ttpux2.physik.uni-karlsruhe.de (129.13.102.139) as /ttp94-18
/ttp94-18.ps, Local preprint# TTP94-1
Disoriented Chiral Condensate: Theory and Experiment
It is thought that a region of pseudo-vacuum, where the chiral order
parameter is misaligned from its vacuum orientation in isospin space, might
occasionally form in high energy hadronic or nuclear collisions. The possible
detection of such disoriented chiral condensate (DCC) would provide useful
information about the chiral structure of the QCD vacuum and/or the chiral
phase transition of strong interactions at high temperature. We review the
theoretical developments concerning the possible DCC formation in high-energy
collisions as well as the various experimental searches that have been
performed so far. We discuss future prospects for upcoming DCC searches, e.g.
in high-energy heavy-ion collision experiments at RHIC and LHC.Comment: 120 pages, 52 figures. Uses elsart.cls. To appear in Physics Reports.
Minor corrections, references adde
Calculation of the Flux of Atmospheric Neutrinos
Atmospheric neutrino-fluxes are calculated over the wide energy range from 30
MeV to 3,000 GeV for the study of neutrino-physics using the data from
underground neutrino-detectors. The atmospheric muon-flux at high altitude and
at sea level is studied to calibrate the neutrino-fluxes at low energies and
high energies respectively. The agreement of our calculation with observations
is satisfactory. The uncertainty of atmospheric neutrino-fluxes is also
studied.Comment: 51 page
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