Soft photons from relativistic heavy ion collisions

Roy, P.; Pal, Dipali; Sarkar, Sourav; Srivastava, D. K.; Sinha, Bikash

doi:10.1103/physrevc.53.2364

Cited by 15 publications

(23 citation statements)

References 40 publications

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“…Secondly, for hadronic reactions we use the state of the art results from Turbide et al [20] along with inclusion of hadronic form-factors at the vortexes, incorporating strange mesons. The dominant hadronic bremsstrahlung process (ππ → ππγ) is included [21] for low k T photons and double counting via ππ → ργ and ρ → ππγ avoided by limiting the contributions of the latter two processes to E γ > 500 MeV. This should be adequate till a more detailed and complete calculation is available.…”

Section: Introductionmentioning

confidence: 99%

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Srivastava

2005

Phys. Rev. C

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Intensity interferometry of thermal photons, having transverse momenta kT ≈ 0.1 -2.0 GeV, produced in relativistic collision of heavy nuclei is studied. It is seen to provide an accurate information about the temporal and spatial structure of the interacting system. The source dimensions and their kT dependence revealed by the photon interferometry, display a richness not seen in pion interferometry. We attribute this to difference in the source functions, the fact that photons come out from every stage of the collision and from every point in the system, and the fact that the rate of production of photons is different for the quark-gluon plasma, which dominates the early hot stage, and the hadronic matter which populates the last phase of the collision dynamics. The usefulness of this procedure is demonstrated by an application to collision of lead nuclei at the CERN SPS. Prediction for the transverse momentum dependence of the sizes for SPS, RHIC, and LHC energies are given.

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Section: Introductionmentioning

confidence: 99%

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Srivastava

2005

Phys. Rev. C

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“…Of course, we must now admit the suggestion of Aurenche et al [9] that the production of photons in a QGP evaluated up to two loops, leads to a large bremsstrahlung contribution (see Ref. [7,8] for early estimates within a soft photon approximation) as well as the new mechanism for the production of hard photons through the annihilation of quarks with scattering, which completely dominates the emission of hard photons.…”

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confidence: 99%

“…During the QGP phase, the single photons originate from Compton (q (q) g → q (q) γ) and annihilation (q q → g γ) processes [5,6] as well as bremsstrahlung processes (q q (g) → q q (g) γ) [7,8]. During the pre-quilibrium phase, which can be treated within the parton cascade model [12], the fragmentation of time-like quarks (q → q γ) produced in (semi)hard multiple scatterings leads to a substantial production of photons (flash of photons!…”

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confidence: 99%

“…Recall that the hadronic reactions considered in the study include the process ππ → ργ which is known to be equivalent to the bremsstrahlung process ππ → ππγ (see Ref. [7,8]). Thus we realize that the bremsstrahlung process in the quark matter contained in the two-loop evaluations of Aurenche et al [9] plays an important role in getting the right shape of the spectrum at lower p T .…”

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confidence: 99%

“…An attempt was also made to evaluate the single photons from the quark matter due the bremsstrahlung processes within the soft-photon approximation which were found to make a large contribution at smaller p T [7,8].…”

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A second look at single-photon production in S + Au collisions at 200 A GeV and implications for quark–hadron phase transition

Srivastava

Sinha

2000

Eur. Phys. J. C

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We reanalyze the production of single photons in S + Au collisions at CERN SPS to investigate: i) the consequences of using a much richer equation of state for hadrons than the one used in an earlier study by us; and, ii) to see if the recent estimates of photon production in quark-matter (at two loop level) by Aurenche et al. are consistent with the upper limit of the photon production measured by the WA80 experiment. We find that the measured upper limit is consistent with a quark hadron phase transition. The measured upper limit is also consistent with a scenario where no phase transition takes place, but where the hadronic matter reaches a density of several hadrons per unit volume; which is rather unphysical.

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Low-energy thermal photons from meson–meson bremsstrahlung

Liu

Rapp

2007

Nuclear Physics A

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Within an effective hadronic model including electromagnetic interactions via a U em (1) gauge, we reinvestigate photon bremsstrahlung from a hot hadronic gas as expected to be formed in relativistic heavy-ion collisions at SPS energies. We calculate photon emission from the reactions ππ → ππγ and πK → πKγ by an explicit (numerical) evaluation of the multi-dimensional phase space integral. This, in particular, allows to avoid the commonly employed soft photon approximation (SPA), as well as to incorporate finalstate thermal enhancement factors. Both improvements are shown to result in an appreciable increase of the photon production rate over previous hadronic calculations. Upon convolution over a thermal fireball we find an improvement in the description of recent low transverse-momentum WA98 data at SPS. The influence of both Landau-Pomeranchuk-Migdal and in-medium effects on "σ " and ρ-meson exchanges are briefly discussed.

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Soft photons from relativistic heavy ion collisions

Cited by 15 publications

References 40 publications

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

A second look at single-photon production in S + Au collisions at 200 A GeV and implications for quark–hadron phase transition

Low-energy thermal photons from meson–meson bremsstrahlung

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