2,324 research outputs found
Correlation measurements in high-multiplicity events
Requirements for correlation measurements in high--multiplicity events are
discussed. Attention is focussed on detection of so--called hot spots,
two--particle rapidity correlations, two--particle momentum correlations (for
quantum interferometry) and higher--order correlations. The signal--to--noise
ratio may become large in the high--multiplicity limit, allowing meaningful
single--event measurements, only if the correlations are due to collective
behavior.Comment: MN 55455, 20 pages, KSUCNR-011-92 and TPI-MINN-92/47-T (revised).
Revised to correct typo in equation (30), and to fill in a few steps in
calculations. Now published as Phys. Rev. C 47 (1993) 232
Hadron widths in mixed-phase matter
We derive classically an expression for a hadron width in a two-phase region
of hadron gas and quark-gluon plasma (QGP). The presence of QGP gives hadrons
larger widths than they would have in a pure hadron gas. We find that the
width observed in a central Au+Au collision at
GeV/nucleon is a few MeV greater than the width in a pure hadron gas. The part
of observed hadron widths due to QGP is approximately proportional to
.Comment: 8 pages, latex, no figures, KSUCNR-002-9
The Carnegie Hubble Program: The Distance and Structure of the SMC as Revealed by Mid-infrared Observations of Cepheids
Using Spitzer observations of classical Cepheids we have measured the true
average distance modulus of the SMC to be mag (corresponding to kpc), which is
mag more distant than the LMC. This is in agreement with previous results from
Cepheid observations, as well as with measurements from other indicators such
as RR Lyrae stars and the tip of the red giant branch.
Utilizing the properties of the mid--infrared Leavitt Law we measured precise
distances to individual Cepheids in the SMC, and have confirmed that the galaxy
is tilted and elongated such that its eastern side is up to 20 kpc closer than
its western side. This is in agreement with the results from red clump stars
and dynamical simulations of the Magellanic Clouds and Stream.Comment: Accepted for publication in ApJ. 38 Pages, 11 figures. Figure 9 is
interactive. Spitzer photometry for all Cepheids available as online tabl
Balance Functions, Correlations, Charge Fluctuations and Interferometry
Connections between charge balance functions, charge fluctuations and
correlations are presented. It is shown that charge fluctuations can be
directly expressed in terms of a balance functions under certain assumptions.
The distortion of charge balance functions due to experimental acceptance is
discussed and the effects of identical boson interference is illustrated with a
simple model.Comment: 1 eps figure included. 5 pages in revtex
Calibration of the Mid-Infrared Tully-Fisher Relation
Distance measures on a coherent scale around the sky are required to address
the outstanding cosmological problems of the Hubble Constant and of departures
from the mean cosmic flow. The correlation between galaxy luminosities and
rotation rates can be used to determine distances to many thousands of galaxies
in a wide range of environments potentially out to 200 Mpc. Mid-infrared (3.6
microns) photometry with the Spitzer Space Telescope is particularly valuable
as the source of the luminosities because it provides products of uniform
quality across the sky. From a perch above the atmosphere, essentially the
total magnitude of targets can be registered in exposures of a few minutes.
Extinction is minimal and the flux is dominated by the light from old stars
which is expected to correlate with the mass of the targets.
In spite of the superior photometry, the correlation between mid-infrared
luminosities and rotation rates extracted from neutral hydrogen profiles is
slightly degraded from the correlation found with I band luminosities. A color
correction recovers a correlation that provides comparable accuracy to that
available at I band (~20% 1sigma in an individual distance) while retaining the
advantages identified above. Without the color correction the relation between
linewidth and [3.6] magnitudes is M^{b,i,k,a}_{[3.6]} = -20.34 - 9.74 (log
W_{mx}^{i} -2.5). This description is found with a sample of 213 galaxies in 13
clusters that define the slope and 26 galaxies with Cepheid or tip of the red
giant branch distances that define the zero point. A color corrected parameter
M_{C_{[3.6]}} is constructed that has reduced scatter: M_{C_{[3.6]}} = -20.34 -
9.13 (log W_{mx}^{i} -2.5). Consideration of the 7 calibration clusters beyond
50 Mpc, outside the domain of obvious peculiar velocities, provides a
preliminary Hubble Constant estimate of H_0=74+/-5 km/s/Mpc.Comment: Accepted for publication in The Astrophysical Journal, 14 pages, 11
figures, 4 table
Secondary phi meson peak as an indicator of QCD phase transition in ultrarelativistic heavy ion collisions
In a previous paper, we have shown that a double phi peak structure appears
in the dilepton invariant mass spectrum if a first order QCD phase transition
occurs in ultrarelativistic heavy ion collisions. Furthermore, the transition
temperature can be determined from the transverse momentum distribution of the
low mass phi peak. In this work, we extend the study to the case that a smooth
crossover occurs in the quark-gluon plasma to the hadronic matter transition.
We find that the double phi peak structure still exists in the dilepton
spectrum and thus remains a viable signal for the formation of the quark-gluon
plasma in ultrarelativistic heavy ion collisions.Comment: 8 pages, 9 uuencoded postscript figures included, Latex, LBL-3572
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