Discovery of higher-order quantum electrodynamics effect for the vacuum pair production

Zha, W.; Tang, Z.

doi:10.1007/jhep08(2021)083

Cited by 16 publications

(7 citation statements)

References 66 publications

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“…Nonetheless, it is interesting to note that both this effect and the impact of unitary corrections is qualitatively to reduce the theoretical cross section, that is in the direction of the data. We also note that a recent study [32] suggests the impact of these higher order corrections could be at the ∼ 10% level, though this is clearly in contradiction with [43] (see also [44] for a review and further references) and indeed the physical expectations discussed above. We note in addition that such effects are clearly not relevant in pp collisions, where there is no corresponding ∼ Z 2 enhancement in the photon flux.…”

Section: Pbpb Collisionscontrasting

confidence: 53%

“…While potentially relevant for the production of strongly interacting states, this is certainly not the case for lepton pairs, see [1,[30][31][32] for discussion. In particular, such a cut effectively assumes the lepton pair can interact strongly with the hadrons, which is certainly not true.…”

Section: Removing the B I⊥ < R A Regionmentioning

confidence: 99%

“…In particular, these higher order QED effects will not be localised in such a way, and will not lead to colour flow between the hadrons at all, and certainly not with unit probability in this region, as such a cut implies. This point has been discussed from a theoretical point of view in [1,[30][31][32], but interestingly in the ATLAS PbPb data [24] there is clear evidence that the shape of the STARlight MC predicted distributions with respect to the muon kinematic variables do not match the data. Indeed, it is suggested in [24] that a loosening of the above requirement may improve the agreement.…”

Section: Introductionmentioning

confidence: 99%

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Elastic photon-initiated production at the LHC: the role of hadron-hadron interactions

2021

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We analyse in detail the role of additional hadron–hadron interactions in elastic photon–initiated (PI) production at the LHC, both in pp and heavy ion collisions. We first demonstrate that the source of difference between our predictions and other results in the literature for PI muon pair production is dominantly due to an unphysical cut that is imposed in these latter results on the dimuon–hadron impact parameter. We in addition show that this is experimentally disfavoured by the shape of the muon kinematic distributions measured by ATLAS in ultraperipheral PbPb collisions. We then consider the theoretical uncertainty due to the survival probability for no additional hadron–hadron interactions, and in particular the role this may play in the tendency for the predicted cross sections to lie somewhat above ATLAS data on PI muon pair production, in both pp and PbPb collisions. This difference is relatively mild, at the \sim 10\%∼10% level, and hence a very good control over the theory is clearly required. We show that this uncertainty is very small, and it is only by taking very extreme and rather unphysical variations in the modelling of the survival factor that this tension can be removed. This underlines the basic, rather model independent, point that a significant fraction of elastic PI scattering occurs for hadron–hadron impact parameters that are simply outside the range of QCD interactions, and hence this sets a lower bound on the survival factor in any physically reasonable approach. Finally, other possible origins for this discrepancy are discussed.

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Section: Pbpb Collisionscontrasting

confidence: 53%

Section: Removing the B I⊥ < R A Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elastic photon-initiated production at the LHC: the role of hadron-hadron interactions

2021

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“…Since the core part is formed from the leading order interaction, which is directly related to the photon 𝑝 𝑇 , the measurements show that the initial photon 𝑝 𝑇 increases with the decrease of impact parameter. STARLIGHT MC [10] does not have this increasing trend but the CMS results are qualitatively described by the leading order QED model [11] calculation, which incorporates the impact parameter dependence of photon 𝑝 𝑇 . Our data results are five times higher than the model because of the absence of higher-order corrections for the soft photon radiation from the produced muon [12].…”

Section: Pos(panic2021)263mentioning

confidence: 93%

Recent heavy ion results from CMS

Behera¹

2022

Proceedings of Particles and Nuclei International Conference 2021 — PoS(PANIC2021)

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The conditions in collisions of ultra-relativistic nuclei correspond to a very early time of the universe. At CERN's Large Hadron Collider (LHC), studies of the properties of the produced hot and dense strongly-interacting matter are carried out by all four big experiments. In this talk, we will give an overview of recent exciting heavy-ion results from the Compact Muon Solenoid experiment. We will cover different areas of interest, such as, heavy-flavour probes on Quark Gluon Plasma (QGP), initial states, and bulk QGP physics.

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“…The discovery of higher order QED effects in high energy particle and nuclear collisions would itself be an important finding. Potential signatures of Coulomb corrections in highenergy EM scattering processes have been thoroughly studied over the last few decades [129,131,132,227]. While significant theoretical differences and uncertainties exist, several authors have predicted that Coulomb corrections modify the total pair photoproduction cross section by as much as 30%.…”

Section: Are Higher Order Effects Present and If So Are They Separabl...mentioning

confidence: 99%

Report on progress in physics: observation of the Breit–Wheeler process and vacuum birefringence in heavy-ion collisions

Brandenburg

Seger

et al. 2023

Rep. Prog. Phys.

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This Report reviews the effort over several decades to observe the linear Breit-Wheeler process ($\gamma\gamma \rightarrow e^+e^-$) and vacuum birefringence in high-energy particle and heavy-ion collider experiment. This Report, motivated by the STAR collaboration's recent observations, attempts to summarize the key issues related to the interpretation of polarized $\gamma\gamma \rightarrow l^+l^-$ measurements in high-energy experiments. To that end, we start by reviewing the historical context and essential theoretical developments, before focusing on the decades of progress made in high-energy collider experiments. Special attention is given to the evolution in experimental approaches in response to various challenges, to the demanding detector capabilities required to unambiguously identify the linear Breit-Wheeler process, and to the connections with vacuum birefringence. We close the report with a discussion, followed by a look at near-future opportunities for utilizing these discoveries and for testing QED in previously unexplored regimes.

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Discovery of higher-order quantum electrodynamics effect for the vacuum pair production

Cited by 16 publications

References 66 publications

Elastic photon-initiated production at the LHC: the role of hadron-hadron interactions

Elastic photon-initiated production at the LHC: the role of hadron-hadron interactions

Recent heavy ion results from CMS

Report on progress in physics: observation of the Breit–Wheeler process and vacuum birefringence in heavy-ion collisions

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