Low Mass Dimuons Produced in Relativistic Nuclear Collisions

Ruppert, Jörg; Gale, Charles; Renk, Thorsten; Lichard, P.; Kapusta, Joseph I.

doi:10.1103/physrevlett.100.162301

Cited by 90 publications

(128 citation statements)

References 28 publications

(41 reference statements)

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“…The ρ pole remains visible, due to the freeze-out part. In-medium broadening of parts of the ω and φ are contained in [20], but not in [19,21], accounting for the broad bump seen in the region of the φ. Caution should, however, be taken as to the nearly quantitative agreement with the data, since some details of the resolution function of the NA60 apparatus are still under investigation.…”

Section: Introductionmentioning

confidence: 97%

“…Extrapolating the lower-mass trend to beyond the ρ, such a fast transition to a seeming low-flow situation is extremely hard to reconcile with emission sources which continue to be of dominantly hadronic origin in this region. A more natural explanation would then be a transition to a dominantly early partonic source with processes like qq → µ + µ − for which flow has not yet built up [19]. While still controversial [20], this may well represent the first direct evidence for thermal radiation of partonic origin, overcoming parton-hadron duality for the yield description in the mass domain.…”

Section: Introductionmentioning

confidence: 98%

“…Beyond (minor) contributions from the spectral function, p T encodes the key properties of the expanding fireball, temperature and transverse (radial) flow. In contrast to hadrons, however, which receive the full asymptotic flow at the [19], HR [20], and DZ [21]. In case of [20], the EoS-B + option is used.…”

Section: Introductionmentioning

confidence: 99%

“…Open charm is subtracted in both parts of the figure. moment of decoupling, dileptons are continuously emitted during the evolution, sensing the space-time development of temperature and flow. This makes the dilepton p T spectra sensitive to the emission region, providing a powerful diagnostic tool [5,19]. Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The LMR and IMR regions are again unified, using an independently assessed absolute normalization [22]. Recent theoretical results from the three major groups working in the field are included for comparison [19,20,21]. A strong rise towards low masses is seen in the data, reflecting the Boltzmann factor, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Thermal dileptons in high-energy nuclear collisions

Damjanović

2009

Progress in Particle and Nuclear Physics

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Clear signs of excess dileptons above the known sources were found at the SPS since long. However, a real clarification of these observations was only recently achieved by NA60, measuring dimuons with unprecedented precision in 158A GeV In-In collisions. The excess mass spectrum in the region M <1 GeV is consistent with a dominant contribution fromThe associated ρ spectral function shows a strong broadening, but essentially no shift in mass. In the region M >1 GeV, the excess is found to be prompt, not due to enhanced charm production. The inverse slope parameter T eff associated with the transverse momentum spectra rises with mass up to the ρ, followed by a sudden decline above. While the initial rise, coupled to a hierarchy in hadron freeze-out, points to radial flow of a hadronic decay source, the decline above signals a transition to a low-flow source, presumably of partonic origin. The mass spectra show the steep rise towards low masses characteristic for Planck-like radiation. The polarization of the excess referred to the Collins Soper frame is found to be isotropic. All observations are consistent with a global interpretation of the excess as thermal radiation. We conclude with a short discussion of a possible link to direct photons.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal dileptons in high-energy nuclear collisions

Damjanović

2009

Progress in Particle and Nuclear Physics

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The Chiral Restoration Transition of QCD and Low Mass Dileptons

Rapp¹,

Wambach²,

Hees³

2010

Relativistic Heavy Ion Physics

108

143

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Recent developments in the evaluation of vector-meson spectral functions in hot and dense matter are discussed with emphasis on connections to the chiral phase transition in QCD. Model independent approaches including chiral low-density expansions, lattice QCD, chiral and QCD sum rules are put into context with model predictions for in-medium vector-spectral function utilizing effective Lagrangians. Hadronic manybody calculations predict a strong broadening (and little mass shift) of the ρ spectral function which rapidly increases close to the expected phase boundary of hadronic and quark-gluon matter. Pertinent dilepton rates appear to degenerate with perturbative quark-antiquark annihilation in the Quark-Gluon Plasma, suggestive for chiral symmetry restoration. Applications to low-mass dilepton spectra in heavy-ion collisions result in quantitative agreement with recent high-quality data at the CERN-SPS. Thermal radiation from temperatures around T c consistently reproduces the experimental dilepton excess observed at masses above 1 GeV as well. The interpretation of dilepton sources at high transverse momentum appears to be more involved.

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Electromagnetic Probes

Tserruya¹

2010

Relativistic Heavy Ion Physics

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A review is presented of dilepton and real photon measurements in relativistic heavy ion collisions over a very broad energy range from the low energies of the BE-VALAC up to the highest energies available at RHIC. The dileptons cover the invariant mass range m l + l − = 0 -2.5 GeV/c 2 , i.e. the continuum at low and intermediate masses and the light vector mesons, ρ, ω, φ. The review includes also measurements of the light vector mesons in elementary reactions.

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Low Mass Dimuons Produced in Relativistic Nuclear Collisions

Cited by 90 publications

References 28 publications

Thermal dileptons in high-energy nuclear collisions

Thermal dileptons in high-energy nuclear collisions

The Chiral Restoration Transition of QCD and Low Mass Dileptons

Electromagnetic Probes

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