Acoplanarity of a Lepton Pair to Probe the Electromagnetic Property of Quark Matter

Klein, S. R.; Mueller, Alfred H.; Xiao, Bo-Wen; Yuan, Feng

doi:10.1103/physrevlett.122.132301

Cited by 66 publications

(42 citation statements)

References 70 publications

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“…The STAR collaboration found an excess with respect to the hadronic expectation of low-p T,ee dielectrons in Au-Au and U-U collisions, which is compatible with calculations for coherent photo-production [1][2][3]6] and which cannot be linked to hadronic sources [7]. The ATLAS collaboration observes photoproduced dimuons in Pb-Pb collisions, which exhibit a centrality dependent broadening effect of their angular pair correlations that seems not to be present in UPC [8,9]. In the following, the first dedicated measurement of low-mass dielectron production at low p T,ee in Pb-Pb collisions at √ s NN = 5.02 TeV is reported and compared to various models of dielectron photo-production.…”

Section: Introductionsupporting

confidence: 67%

“…Apart from including resolution effects in the model calculations, an extension of the analysis in terms of mass and centrality range is foreseen, which should allow for more differential studies. These may address the geometry of the initial electromagnetic field and its fluctuations, effects of the strong magnetic field, and interactions with the medium [9,21,23,24]. Data recorded in 2018 are currently becoming available and will approximately double the data set size in peripheral collision, which will further benefit these analyses.…”

Section: Discussionmentioning

confidence: 99%

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Dielectron production at low transverse momentum in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=5.02 $ TeV with ALICE

Lehner¹

2019

Proceedings of 7th Annual Conference on Large Hadron Collider Physics — PoS(LHCP2019)

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Dielectrons probe a wide range of phenomena in heavy-ion collisions. These include lightand heavy-flavour meson production, thermal radiation and coherent photo-production. The latter process is distinguished by dielectron production at low transverse-pair momentum (p T,ee ). Transverse momentum spectra of dielectrons in central and peripheral Pb-Pb collisions are extracted and compared to the corresponding expectations. In central collisions the data fit the expected spectrum, which is dominated by semi-leptonic decays of correlated heavy-flavour hadrons. In peripheral collisions, the data exhibit an excess at low p T,ee with respect to hadronic and thermal sources. The observed excess yield is compatible with calculations for dielectron production from coherent photon-photon interactions.

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Section: Introductionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Dielectron production at low transverse momentum in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=5.02 $ TeV with ALICE

Lehner¹

2019

Proceedings of 7th Annual Conference on Large Hadron Collider Physics — PoS(LHCP2019)

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“…There have been proposals in the literature regarding possible final-state effects to explain the P ⊥ broadening. Two such proposals are that the broadening is due to deflection by the residual magnetic field trapped in an electrically conducting QGP [24,37] or due to multiple Coulomb scattering in the hot and dense medium [25,33]. All the proposed mechanisms including this study require extraordinarily strong electromagnetic fields, an interdisciplinary subject of intense interest across many scientific communities.…”

mentioning

confidence: 98%

Initial transverse-momentum broadening of Breit-Wheeler process in relativistic heavy-ion collisions

et al. 2020

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We calculate the cross section and transverse-momentum (P ⊥ ) distribution of the Breit-Wheeler process in relativistic heavy-ion collisions and their dependence on collision impact parameter (b). To accomplish this, the Equivalent Photon Approximation (EPA) was generalized in a more differential way compared to the approach traditionally used for inclusive collisions. In addition, a lowest-order QED calculation with straightline assumption was performed as a standard baseline for comparison. The cross section as a function of b is consistent with previous calculations using the equivalent one-photon distribution function. Most importantly, the P ⊥ shape from this model is strongly dependent on impact parameter and can quantitatively explain the P ⊥ broadening observed recently by RHIC and LHC experiments. This broadening effect from the initial QED field strength should be considered in studying possible trapped magnetic field and multiple scattering in a Quark-Gluon Plasma (QGP). The impact-parameter sensitive observable also provides a controllable tool for studying extreme electromagnetic fields.

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“…Other potentially important effects such as Sudakov resummation of soft photon emissions and a possible rescat-tering of dileptons in the plasma have been recently discussed in Ref. [82].…”

Section: Low Transverse Momentum Dilepton Production In Semicentral Hmentioning

confidence: 99%

Photon induced processes: from ultraperipheral to semicentral heavy ion collisions

Schäfer

2020

Eur. Phys. J. A

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We present an overview of processes induced by the coherent Weizsäcker-Williams (WW) photon cloud in heavy ion collisions. Due to the rather broad energy spectrum of photons a large variety of physics topics can be addressed. At the low-energy side, there are the electromagnetic dissociation processes. We discuss the few-neutron production via giant dipole resonance excitation. A typical high energy photonuclear process that has attracted much attention is the diffractive photoproduction of vector mesons. We review the color dipole approach to coherent and incoherent diffractive photoproduction of $$J/\psi $$ J / ψ mesons. Finally we turn to peripheral and semicentral collisions and discuss the role of WW photons in the production of very low-$$P_T$$ P T dileptons.

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Acoplanarity of a Lepton Pair to Probe the Electromagnetic Property of Quark Matter

Cited by 66 publications

References 70 publications

Dielectron production at low transverse momentum in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=5.02 $ TeV with ALICE

Dielectron production at low transverse momentum in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=5.02 $ TeV with ALICE

Initial transverse-momentum broadening of Breit-Wheeler process in relativistic heavy-ion collisions

Photon induced processes: from ultraperipheral to semicentral heavy ion collisions

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