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Title: Evidence for a Long-Range Component in the Pion Emission Source in Au+Au Collisions at {radical}(s{sub NN})=200 GeV

Abstract

Emission source functions are extracted from correlation functions constructed from charged pions produced at midrapidity in Au+Au collisions at {radical}(s{sub NN})=200 GeV. The source parameters extracted from these functions at low k{sub T} give first indications of a long tail for the pion emission source. The source extension cannot be explained solely by simple kinematic considerations. The possible role of a halo of secondary pions from resonance emissions is explored.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. Brookhaven National Laboratory, Upton, New York 11973-5000 (United States) (and others)
Publication Date:
OSTI Identifier:
20951185
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 13; Other Information: DOI: 10.1103/PhysRevLett.98.132301; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COLLIDING BEAMS; CORRELATION FUNCTIONS; GEV RANGE 100-1000; GOLD 197 BEAMS; GOLD 197 REACTIONS; GOLD 197 TARGET; PARTICLE PRODUCTION; PIONS

Citation Formats

Adler, S. S., Aidala, C., Aronson, S. H., Chujo, T., David, G., Desmond, E. J., Ewell, L., Franz, A., Guryn, W., Haggerty, J. S., Harvey, M., Johnson, B. M., Kistenev, E., Kroon, P. J., Makdisi, Y. I., Mioduszewski, S., Mitchell, J. T., Morrison, D. P., O'Brien, E., and Pinkenburg, C. Evidence for a Long-Range Component in the Pion Emission Source in Au+Au Collisions at {radical}(s{sub NN})=200 GeV. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.132301.
Adler, S. S., Aidala, C., Aronson, S. H., Chujo, T., David, G., Desmond, E. J., Ewell, L., Franz, A., Guryn, W., Haggerty, J. S., Harvey, M., Johnson, B. M., Kistenev, E., Kroon, P. J., Makdisi, Y. I., Mioduszewski, S., Mitchell, J. T., Morrison, D. P., O'Brien, E., & Pinkenburg, C. Evidence for a Long-Range Component in the Pion Emission Source in Au+Au Collisions at {radical}(s{sub NN})=200 GeV. United States. doi:10.1103/PHYSREVLETT.98.132301.
Adler, S. S., Aidala, C., Aronson, S. H., Chujo, T., David, G., Desmond, E. J., Ewell, L., Franz, A., Guryn, W., Haggerty, J. S., Harvey, M., Johnson, B. M., Kistenev, E., Kroon, P. J., Makdisi, Y. I., Mioduszewski, S., Mitchell, J. T., Morrison, D. P., O'Brien, E., and Pinkenburg, C. Fri . "Evidence for a Long-Range Component in the Pion Emission Source in Au+Au Collisions at {radical}(s{sub NN})=200 GeV". United States. doi:10.1103/PHYSREVLETT.98.132301.
@article{osti_20951185,
title = {Evidence for a Long-Range Component in the Pion Emission Source in Au+Au Collisions at {radical}(s{sub NN})=200 GeV},
author = {Adler, S. S. and Aidala, C. and Aronson, S. H. and Chujo, T. and David, G. and Desmond, E. J. and Ewell, L. and Franz, A. and Guryn, W. and Haggerty, J. S. and Harvey, M. and Johnson, B. M. and Kistenev, E. and Kroon, P. J. and Makdisi, Y. I. and Mioduszewski, S. and Mitchell, J. T. and Morrison, D. P. and O'Brien, E. and Pinkenburg, C.},
abstractNote = {Emission source functions are extracted from correlation functions constructed from charged pions produced at midrapidity in Au+Au collisions at {radical}(s{sub NN})=200 GeV. The source parameters extracted from these functions at low k{sub T} give first indications of a long tail for the pion emission source. The source extension cannot be explained solely by simple kinematic considerations. The possible role of a halo of secondary pions from resonance emissions is explored.},
doi = {10.1103/PHYSREVLETT.98.132301},
journal = {Physical Review Letters},
number = 13,
volume = 98,
place = {United States},
year = {Fri Mar 30 00:00:00 EDT 2007},
month = {Fri Mar 30 00:00:00 EDT 2007}
}
  • A three-dimensional correlation function obtained from midrapidity, low p{sub T}, pion pairs in central Au+Au collisions at {radical}(s{sub NN})=200 GeV is studied. The extracted model-independent source function indicates a long range tail in the directions of the pion pair transverse momentum (out) and the beam (long). A proper breakup time {tau}{sub 0}{approx}9 fm/c and a mean proper emission duration {delta}{tau}{approx}2 fm/c, leading to sizable emission time differences (<|{delta}t{sub LCM}|>{approx_equal}12 fm/c), are required to allow models to be successfully matched to these tails. The model comparisons also suggest an outside-in 'burning' of the emission source reminiscent of many hydrodynamical models.
  • Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV. Strong short- and long-range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short-range correlations are observed in peripheral Au+Au collisions. Both the dual parton model (DPM) and the color glass condensate (CGC) predict the existence of the long-range correlations. In the DPM, the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC, longitudinal color flux tubes generate the LRC. The datamore » are in qualitative agreement with the predictions of the DPM and indicate the presence of multiple parton interactions.« less
  • I present the first isolation of azimuth quadrupole components from published v{sub 2}(p{sub t}) data (called elliptic flow) as spectra on transverse rapidity y{sub t} for identified pions, kaons, and {lambda}'s/protons from minimum-bias Au-Au collisions at 200 GeV. The form of the spectra on y{sub t} indicates that the three hadron species are emitted from a common boosted source with boost {delta}y{sub t0}{approx}0.6. The quadrupole spectra have a Levy form similar to the soft component of the single-particle spectrum, but with significantly reduced ({approx}0.7 times) slope parameters T. Comparison of quadrupole spectra with single-particle spectra suggests that the quadrupole componentmore » comprises a small fraction (<5%) of the total hadron yield, contradicting the hydrodynamic picture of a thermalized, flowing bulk medium. The form of v{sub 2}(p{sub t}) is, within a constant factor, the product of p{sub t}{sup '} (p{sub t} in the boost frame) times the ratio of quadrupole spectrum to single-particle spectrum. That ratio in turn implies that above 0.5 GeV/c, the form of v{sub 2}(p{sub t}) is dominated by the hard component of the single-particle spectrum (interpreted as being due to minijets). It is therefore unlikely that the so-called constituent-quark scaling attributed to v{sub 2} is relevant to soft hadron production mechanisms (e.g., chemical freeze-out)« less
  • Measurements of neutral pion ({pi}{sup 0}) production at midrapidity in {radical}(s{sub NN})=200 GeV Au+Au collisions as a function of transverse momentum, p{sub T}, collision centrality, and angle with respect to reaction plane are presented. The data represent the final {pi}{sup 0} results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of 3 increase in statistics over previously published results for p{sub T}>6 GeV/c. We evaluate the suppression in the yield of high-p{sub T} {pi}{sup 0}'s relative to pointlike scalingmore » expectations using the nuclear modification factor R{sub AA}. We present the p{sub T} dependence of R{sub AA} for nine bins in collision centrality. We separately integrate R{sub AA} over larger p{sub T} bins to show more precisely the centrality dependence of the high-p{sub T} suppression. We then evaluate the dependence of the high-p{sub T} suppression on the emission angle {delta}{phi} of the pions with respect to event reaction plane for seven bins in collision centrality. We show that the yields of high-p{sub T} {pi}{sup 0}'s vary strongly with {delta}{phi}, consistent with prior measurements 1,2. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane, whereas the yield of {pi}{sup 0}'s produced perpendicular to the reaction plane is suppressed by a factor of {approx}2. We analyze the combined centrality and {delta}{phi} dependence of the {pi}{sup 0} suppression in different p{sub T} bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.« less
  • The results of midrapidity (0 < y < 0.8) neutral pion spectra over an extended transverse momentum range (1 < p{sub T} < 12 GeV/c) in {radical}{ovr s}{sub NN} = 200 GeV Au+Au collisions, measured by the STAR experiment, are presented. The neutral pions are reconstructed from photons measured either by the STAR Barrel Electro-Magnetic Calorimeter or by the Time Projection Chamber via tracking of conversion electron-positron pairs. Our measurements are compared to previously published {pi}{sup {+-}} and {pi}{sup 0} results. The nuclear modification factors R{sub CP} and R{sub AA} of {pi}{sup 0} are also presented as a function ofmore » p{sub T}. In the most central Au+Au collisions, the binary collision scaled {pi}{sup 0} yield at high p{sub T} is suppressed by a factor of about 5 compared to the expectation from the yield of p+p collisions. Such a large suppression is in agreement with previous observations for light quark mesons and is consistent with the scenario that partons suffer considerable energy loss in the dense medium formed in central nucleus-nucleus collisions at the Relativistic Heavy Ion Collider.« less