scholarly journals Direct Photons from Hot Quark Matter in Renormalized Finite-Time-Path QED

Particles ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 676-692
Author(s):  
Ivan Dadić ◽  
Dubravko Klabučar ◽  
Domagoj Kuić
Keyword(s):  
Finite Time ◽  
Photon Emission ◽  
Heavy Ion ◽  
Uncertainty Relations ◽  
Quantum Field ◽  
Direct Photons ◽  
Basic Difference ◽  
Time Path ◽  
Ion Collisions ◽  
Hot Quark Matter

Within the finite-time-path out-of-equilibrium quantum field theory (QFT), we calculate direct photon emission from early stages of heavy ion collisions, from a narrow window, in which uncertainty relations are still important and they provide a new mechanism for production of photons. The basic difference with respect to earlier calculations, leading to diverging results, is that we use renormalized QED of quarks and photons. Our result is a finite contribution that is consistent with uncertainty relations.

scholarly journals Causality and Renormalization in Finite-Time-Path Out-of-Equilibrium ϕ3 QFT

Particles ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Ivan Dadić ◽  
Dubravko Klabučar
Keyword(s):  
Finite Time ◽  
Matrix Theory ◽  
Heavy Ion ◽  
Potential Conflict ◽  
Composite Object ◽  
Self Energy ◽  
Time Path ◽  
Ion Collisions ◽  
S Matrix ◽  
Short Time

Our aim is to contribute to quantum field theory (QFT) formalisms useful for descriptions of short time phenomena, dominant especially in heavy ion collisions. We formulate out-of-equilibrium QFT within the finite-time-path formalism (FTP) and renormalization theory (RT). The potential conflict of FTP and RT is investigated in g ϕ 3 QFT, by using the retarded/advanced ( R / A ) basis of Green functions and dimensional renormalization (DR). For example, vertices immediately after (in time) divergent self-energy loops do not conserve energy, as integrals diverge. We “repair” them, while keeping d < 4 , to obtain energy conservation at those vertices. Already in the S-matrix theory, the renormalized, finite part of Feynman self-energy Σ F ( p 0 ) does not vanish when | p 0 | → ∞ and cannot be split to retarded and advanced parts. In the Glaser–Epstein approach, the causality is repaired in the composite object G F ( p 0 ) Σ F ( p 0 ) . In the FTP approach, after repairing the vertices, the corresponding composite objects are G R ( p 0 ) Σ R ( p 0 ) and Σ A ( p 0 ) G A ( p 0 ) . In the limit d → 4 , one obtains causal QFT. The tadpole contribution splits into diverging and finite parts. The diverging, constant component is eliminated by the renormalization condition ⟨ 0 | ϕ | 0 ⟩ = 0 of the S-matrix theory. The finite, oscillating energy-nonconserving tadpole contributions vanish in the limit t → ∞ .

scholarly journals Signatures of QGP at RHIC and the LHC

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
T. Niida ◽  
Y. Miake
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
High Energy ◽  
Jet Quenching ◽  
Theoretical Studies ◽  
Debye Screening ◽  
Direct Photons ◽  
Ion Collisions ◽  
Experimental And Theoretical Studies

AbstractThe progress over the 30 years since the first high-energy heavy-ion collisions at the BNL-AGS and CERN-SPS has been truly remarkable. Rigorous experimental and theoretical studies have revealed a new state of the matter in heavy-ion collisions, the quark-gluon plasma (QGP). Many signatures supporting the formation of the QGP have been reported. Among them are jet quenching, the non-viscous flow, direct photons, and Debye screening effects. In this article, selected signatures of the QGP observed at RHIC and the LHC are reviewed.

Study the early stage of heavy ion collisions with direct photons

2014 ◽  
Vol 29 ◽  
pp. 1460230 ◽  
Author(s):  
Fu-Ming Liu ◽  
Sheng-Xu Liu
Keyword(s):  
Collective Motion ◽  
Early Stage ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Transverse Momentum Spectrum ◽  
Direct Photons ◽  
Ion Collisions ◽  
Phenix Collaboration ◽  
Early Beginning ◽  
Hadronic Data

Based on the modelling of the collective motion in AuAu collisions at [Formula: see text] at centrality 0-20% and 20-40% and PbPb collisions at [Formula: see text] at centrality 0-40% with a 3+1D event-averaged ideal hydrodynamics constrained with hadronic data, we study the transverse momentum spectrum and elliptic flow of direct photons and find that the recent direct photon data from both PHENIX collaboration at RHIC and ALICE collaboration at LHC favour an early beginning of collective expansion (τ0 < 0.6 fm/c) and a late formation of quark gluon plasma (τ ~ 2 fm/c).

scholarly journals Recent results from PHENIX at RHIC

2019 ◽  
Vol 204 ◽  
pp. 01017
Author(s):  
Victor Riabov
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Hadron Production ◽  
Large Datasets ◽  
Experimental Results ◽  
Relativistic Heavy Ion Collider ◽  
Direct Photons ◽  
Angular Correlations ◽  
Phenix Experiment ◽  
Ion Collisions

The PHENIX experiment at the relativistic heavy ion collider (RHIC) finished data taking in 2016. However, large datasets collected in different collision systems (p+p, p+A and A+A) at different energies (√sNN = 19-500 GeV) during the last years of the detector operation are actively analysed by the collaboration and bring a wealth of new experimental results. This paper reviews the most recent PHENIX results on the light flavour hadron production, yields and angular correlations of the direct photons in heavy-ion collisions as well as on the search for the onset of collectivity in high multiplicity p+p and p+A collisions.

scholarly journals Hadronic and partonic sources of direct photons in relativistic heavy-ion collisions

2015 ◽  
Vol 92 (5) ◽  
Author(s):  
O. Linnyk ◽  
V. Konchakovski ◽  
T. Steinert ◽  
W. Cassing ◽  
E. L. Bratkovskaya
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Direct Photons ◽  
Ion Collisions

DILEPTONS AND PHOTONS IN HIGH ENERGY HEAVY ION REACTIONS: A REVIEW

1991 ◽  
Vol 06 (04) ◽  
pp. 517-558 ◽  
Author(s):  
SIBAJI RAHA ◽  
BIKASH SINHA
Keyword(s):  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
High Energy ◽  
Direct Photons ◽  
Ion Collisions ◽  
State Of Matter ◽  
Ultrarelativistic Heavy Ion Collisions ◽  
New State Of Matter

We review the production of dilepton pairs, direct photons and diphoton pairs in ultrarelativistic heavy ion collisions, with special attention to the applicability of these particles as the signal for a new state of matter—the quark-gluon plasma.

ROLE OF BARYONIC RESONANCES IN VIRTUAL PHOTON EMISSION IN ELEMENTARY AND HEAVY-ION COLLISIONS

2014 ◽  
Vol 26 ◽  
pp. 1460052 ◽  
Author(s):  
◽  
TETYANA GALATYUK
Keyword(s):  
Invariant Mass Distribution ◽  
Photon Emission ◽  
Heavy Ion ◽  
Medium Effect ◽  
Reference Spectrum ◽  
Electron Pairs ◽  
Ion Collisions ◽  
Energy Domain ◽  
First Time

The HADES experiment aims to explore strongly interacting baryon dominated matter at moderate temperatures using rare and penetrating probes. Special emphasis is put on the region of moderate beam energies where comparatively long-lived states of compressed matter are created. In the energy domain of 1–2 GeV per nucleon, HADES has measured hadrons and di-electron signals in C + C , Ar + KCl , p+p, d+p and p+ Nb collisions. For the first time the electron pairs were reconstructed from quasi-free n+p sub-reactions by detecting the proton spectator from the deuteron breakup. For the first time di-electrons radiated from cold nuclear matter in a kinematic regime, where strong medium effects are expected, have been detected. An experimentally constrained N + N reference spectrum was established. A direct comparison of the N + N reference spectrum with the e+e- invariant mass distribution measured in the heavier system Ar + KCl at 1.76 GeV/u shows an excess yield above the reference. The observation may be interpreted as the onset of an actual medium effect. We argue, that couplings between the ρ meson and the baryonic resonances are of fundamental importance in understanding dilepton spectra at SIS energies.

AZIMUTHAL ANISOTROPY MEASUREMENT OF DIRECT PHOTON IN $\sqrt{^SNN} = 200\ {\rm GeV}$Au + Au COLLISIONS AT RHIC-PHENIX

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2160-2165
Author(s):  
◽  
KENTARO MIKI
Keyword(s):  
Heavy Ion ◽  
Azimuthal Anisotropy ◽  
Dense Medium ◽  
High Transverse Momentum ◽  
Initial State ◽  
Direct Photons ◽  
Ion Collisions ◽  
Hadron Decay ◽  
Decay Photon ◽  
Anisotropy Measurement

Azimuthal anisotropy of direct photons is measured in [Formula: see text] Au + Au collisions by the PHENIX experiment at RHIC. Direct photons are one of the most effective probes to study properties of hot dense medium at initial state (also QGP state) of heavy ion collisions because photons do not interact strongly with medium once produced. They keep their conditions when they are created. Within statistical and systematic errors, the elliptic flow parameter (v2) of direct photons is consistent with zero. Direct photons v2 is measured by the hadron decay photon background v2 from inclusive photon v2 in intermediate to high transverse momentum (pT) region (0 to 10 GeV/c) for 3 centrality selections (20% steps) and minimum bias.

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