Melting rho meson and thermal dileptons

Rapp, Ralf; Hees, Hendrik van; Strong, Trenton

doi:10.1590/s0103-97332007000500026

Cited by 14 publications

(13 citation statements)

References 22 publications

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“…In previous works [15,24,36] this was done by running the fireball an extra ∼1 fm/c using the in-medium ρ spectral function. It turns out [19,20], however, that this description of ρ decays at thermal freezeout carries an extra factor of 1/γ relative to a standard blast-wave spectrum of hadrons at thermal freezeout, where γ = q 0 /M is the usual Lorentz factor. Roughly speaking, the inmedium radiation given by Eq.…”

Section: A ρ Mesons At Thermal Freezeoutmentioning

confidence: 99%

“…[95]). Specifically, we evaluate the following scenarios, as sum-marized in the six panels of [15][16][17][18][19][20] MeV in the LMR, approximately reflecting the increase in the hadronic fireball temperatures (e.g., T fo = 136 MeV compared to T fo = 120 MeV at thermal freezeout). Scenario EoS-B (b) additionally improves around the ρ peak due to a larger weight of the relatively hard components from decays of freezeout and primordial ρ, since the overall thermal hadronic emission is smaller than for EoS-A and EoS-C (compare Fig.…”

Section: Slope Analysismentioning

confidence: 99%

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Dilepton radiation at the CERN super-proton synchrotron

2008

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A quantitative evaluation of dilepton sources in heavy-ion reactions is performed taking into account both thermal and non-thermal production mechanisms. The hadronic thermal emission rate is based on an electromagnetic current-correlation function with a low-mass region (LMR, M 1 GeV) dominated by vector mesons (ρ, ω, φ) and an intermediate-mass region (IMR, 1 GeV ≤ M ≤ 3 GeV) characterized by (the onset of) a multi-meson continuum. A convolution of the emission rates over a thermal fireball expansion results in good agreement with experiment in the low-mass spectra, confirming the predicted broadening of the ρ meson in hadronic matter in connection with the prevalence of baryon-induced medium effects. The absolute magnitude of the LMR excess is mostly controlled by the fireball lifetime, which in turn leads to a consistent explanation of the dilepton excess in the IMR in terms of thermal radiation. The analysis of experimental transversemomentum (qT ) spectra reveals discrepancies with thermal emission for qT 1 GeV in noncentral In-In collisions, which we address by extending our calculations by: (i) a refined treatment of ρ decays at thermal freezeout, (ii) primordially produced ρ's subject to energy-loss, (iii) Drell-Yan annihilation, and (iv) thermal radiation from t-channel meson exchange processes. We investigate the sensitivity of dilepton spectra to the critical temperature and hadro-chemical freezeout of the fireball. The ρ broadening in the LMR turns out to be robust, while in the IMR Quark-Gluon Plasma radiation is moderate unless the critical temperature is rather low.

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Section: A ρ Mesons At Thermal Freezeoutmentioning

confidence: 99%

Section: Slope Analysismentioning

confidence: 99%

Dilepton radiation at the CERN super-proton synchrotron

2008

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“…It was seen that a large excess remained after subtracting contributions from expected hadronic (the cocktail) decays. The remaining excess was examined by a number of groups [5,6,7,8,9] and was interpreted by a combination of thermal partonic and hadronic contributions with modifications to the spectral function due to finite temperature and baryon density.…”

Section: Introductionmentioning

confidence: 99%

Transverse momentum spectra of dileptons measured by the NA60 Collaboration inIn+Incollisions at 158 GeV/nucleon

Dusling

Zahed

2009

Phys. Rev. C

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Recently the NA60 collaboration has reported the transverse mass spectra of dimuons coming from In-In collisions at 158 GeV/A. The measured yields display a strong invariant mass dependence not typical of radial flow, suggesting that different sources contribute in different mass regions. We interpret the dimuon transverse mass spectra from an early thermalized partonic phase and hadronic phase constrained by the strictures of broken chiral symmetry. Each phase develops a specific transverse momentum dependence by hydrodynamical expansion. We show that a measurement of the momentum anisotropy at NA60 could provide information on the dominant emission source (hadronic or partonic) in the intermediate mass region 1.5 ≤ M ≤ 3.0 GeV.

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“…Quantitative theoretical analyses [106,136] are rather involved, see the center and right panels of Fig. 19, especially for momenta above q t ≃ 1 − 1.5 GeV where nonthermal sources are expected to become significant [137], e.g., Drell-Yan dileptons or primordial ρ decays.…”

Section: Lmr-imr Transition: Chiral Mixingmentioning

confidence: 99%

Electromagnetic Probes at Rhic-Ii

David

2007

Int. J. Mod. Phys. E

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We summarize how future measurements of electromagnetic (EM) probes at the Relativistic Heavy Ion Collider (RHIC), in connection with theoretical analysis, can advance our understanding of strongly interacting matter at high energy densities and temperatures. After a brief survey of the important role that EM probes data have played at the Super Proton Synchrotron (SPS, CERN) and RHIC to date, we identify key physics objectives and observables that remain to be addressed to characterize the (strongly interacting) Quark-Gluon Plasma (sQGP) and associated transition properties at RHIC. These include medium modifications of vector mesons via low-mass dileptons, a temperature measurement of the hot phases via continuum radiation, as well as γ-γ correlations to characterize early source sizes. We outline strategies to establish microscopic matter and transition properties such as the number of degrees of freedom in the sQGP, the origin of hadron masses and manifestations of chiral symmetry restoration, which will require accompanying but rather well-defined advances in theory. Increased experimental precision, an order of magnitude higher statistics than currently achievable, as well as a detailed scan of colliding species and energies are mandatory to discriminate between theoretical interpretations. This increased precision can be achieved through hardware upgrades to the large RHIC detectors (PHENIX and STAR) along with at least a factor of ten increase in luminosity over the next few years, as envisioned for RHIC-II.

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Melting rho meson and thermal dileptons

Cited by 14 publications

References 22 publications

Dilepton radiation at the CERN super-proton synchrotron

Dilepton radiation at the CERN super-proton synchrotron

Transverse momentum spectra of dileptons measured by the NA60 Collaboration inIn+Incollisions at 158 GeV/nucleon

Electromagnetic Probes at Rhic-Ii

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