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Chiu, M.; Denisov, A.; Garcia, E. Oliver; Katzy, J.; Makeev, A.; Murray, M.; White, S.

doi:10.1103/physrevlett.89.012302

Cited by 48 publications

(47 citation statements)

References 15 publications

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“…[84] predicts that ∼50%-70% of RHIC collisions occur without electromagnetic excitation. The largest partial channel is one-neutron emission, 1n, followed by two-neutron emission, 2n, about 35% of 1n events, and a long tail with a broad and falling distribution [109][110][111][112]. On the other hand, two-neutron emission is most probable for the quasi-elastic mechanism.…”

Section: Light Vector Meson Productionmentioning

confidence: 99%

The physics of ultraperipheral collisions at the LHC

et al. 2008

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229 Pages, 121 figuresWe discuss the physics of large impact parameter interactions at the LHC: ultraperipheral collisions (UPCs). The dominant processes in UPCs are photon-nucleon (nucleus) interactions. The current LHC detector configurations can explore small $x$ hard phenomena with nuclei and nucleons at photon-nucleon center-of-mass energies above 1 TeV, extending the $x$ range of HERA by a factor of ten. In particular, it will be possible to probe diffractive and inclusive parton densities in nuclei using several processes. The interaction of small dipoles with protons and nuclei can be investigated in elastic and quasi-elastic $J/\psi$ and $\Upsilon$ production as well as in high $t$ $\rho^0$ production accompanied by a rapidity gap. Several of these phenomena provide clean signatures of the onset of the new high gluon density QCD regime. The LHC is in the kinematic range where nonlinear effects are several times larger than at HERA. Two-photon processes in UPCs are also studied. In addition, while UPCs play a role in limiting the maximum beam luminosity, they can also be used a luminosity monitor by measuring mutual electromagnetic dissociation of the beam nuclei. We also review similar studies at HERA and RHIC as well as describe the potential use of the LHC detectors for UPC measurements

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Section: Light Vector Meson Productionmentioning

confidence: 99%

The physics of ultraperipheral collisions at the LHC

et al. 2008

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“…The nuclear breakup was calculated using a phenomenological model based on photodissociation data as imput for Weizsäcker-Williams calculations [11] for mutual Coulomb dissociation [12] that was found to successfully reproduce cross sections for mutual Coulomb dissociation observed in the zero degree calorimeters at RHIC [13]. This phenomenological approach to the nuclear breakup was further incorporated in successful calculations of tagged vector meson production probabilities at RHIC [14,15].…”

mentioning

confidence: 99%

Evidence for Higher Order QED Effects ine+e−Pair Production at the BNL Relativistic Heavy Ion Collider

Baltz

2008

Phys. Rev. Lett.

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A new lowest order QED calculation for RHIC e + e − pair production has been carried out with a phenomenological treatment of the Coulomb dissociation of the heavy ion nuclei observed in the STAR ZDC triggers. The lowest order QED result for the experimental acceptance is nearly two standard deviations larger than the STAR data. A corresponding higher order QED calculation is consistent with the data. PACS: 25.75.-q, 34.90.+q In a recent publication data were presented by the RHIC STAR collaboration on "Production of e + e − pairs accompanied by nuclear dissociation in ultraperipheral heavy-ion collisions" [1]. In this publication the authors compared the experimental cross section σ with a lowest order QED calculation σ QED and concluded that "At a 90% confidence level, higher-order corrections to the cross section, ∆σ = σ − σ QED must be within the range −0.5σ QED < ∆σ < 0.2σ QED ".In this Letter, I will present a new lowest order QED cross section calculation result significantly larger than that presented in the STAR publication. This new lowest order QED cross section is now two standard deviations above the STAR experimental result. Furthermore, I find that a higher order QED calculation gives good agreement with the experimental result.The STAR experimental cross sections are for a final state with an e + e − pair in combination with mutual nuclear excitation of both ions by the ions' Coulomb fields observed in the Zero Degree Calorimeters (ZDC). Thus impact parameter dependent probabilities have to be calculated both for e + e − pair production and for mutual Coulomb dissociation of the ions.The calculations presented here make use of the method of calculating the impact parameter dependent probability of producing e + e − pairs previously described [2]. Use of an appropriate gauge allowed the electromagnetic fields of colliding ions to be represented as colliding delta functions in the ultrarelativisitic limit. The solution of the time-dependent Dirac equation for lepton pair production was thereby obtained in closed form. This solution contains higher order QED effects and goes to the known perturbative (lowest order) result in that limit. It is well known that photoproduction of e + e − pairs on a heavy target shows a negative (Coulomb) correction proportional to Z 2 that is well described by the Bethe-Maximon theory [3]. The calculated higher order heavy ion pair production cross sections show analogous reductions from perturbation theory.The impact parameter (b) dependent amplitude presents a particular numerical challenge since it involves the a rapidly oscillating phase exp(ik · b) in the integral over the transverse momentum k transfered from the ion to the lepton pair. The usual method of evaluating the perturbative impact parameter dependent probability is to first square the amplitude and then integrate over the sum and difference of k and k ′ . Here I have integrated before squaring, and I deal with the rapid oscillations with the piecewise analytical integration method previously describe...

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“…The ratios of 1n and 2n emission cross sections of mutual electromagnetic dissociation in (60 + 60) A-GeV AuAu collisions were recently measured at RHIC [18]. The ratios of these ED cross sections to the total reaction cross section were also obtained.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, to what extent do Au electromagnetic dissociation data serve this purpose? Presently there exist single dissociation data for Au nuclei obtained at GSI SIS [16] and at CERN SPS [17] and mutual dissociation data recently obtained at RHIC [18].…”

Section: Introductionmentioning

confidence: 99%

Neutron emission in electromagnetic dissociation of ultrarelativistic Pb ions

Golubeva¹,

Guber²,

Karavicheva³

et al. 2005

Phys. Rev. C

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New data on forward neutron emission in fragmentation of Pb ions on Al, Cu, Sn, and Pb nuclei are presented. The measurements were performed at the CERN SPS in the framework of the ALICE-LUMI experiment. The measured cross sections are compared with predictions of the RELDIS model for electromagnetic interactions and with results of the abrasion-ablation model for hadronic interactions. The electromagnetic excitation of a Pb projectile followed by single-and double-neutron emission is found to be the dominant process in full agreement with theoretical estimations. The measured 1nX cross sections are generally well described. The measured 2nX data, which are 4-5 times lower than the 1nX data, are slightly underestimated by theory. Nevertheless, the sum of 1nX and 2nX cross sections is in good agreement with theory. This confirms the predictive power of the RELDIS model, which can be used to calculate the sum of 1nX and 2nX emission rates for the purpose of calibration of luminosity measurements in PbPb collisions at the Large Hadron Collider at CERN.

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Measurement of Mutual Coulomb Dissociation insNN=130GeV
M. Chiu
¹
,
A. Denisov
²
,
E. Oliver Garcia
³

et al.

Cited by 48 publications

References 15 publications

The physics of ultraperipheral collisions at the LHC

The physics of ultraperipheral collisions at the LHC

Evidence for Higher Order QED Effects ine+e−Pair Production at the BNL Relativistic Heavy Ion Collider

Neutron emission in electromagnetic dissociation of ultrarelativistic Pb ions

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Measurement of Mutual Coulomb Dissociation insNN=130GeVM. Chiu1, A. Denisov2, E. Oliver Garcia3 et al.

Cited by 48 publications

References 15 publications

The physics of ultraperipheral collisions at the LHC

The physics of ultraperipheral collisions at the LHC

Evidence for Higher Order QED Effects ine+e−Pair Production at the BNL Relativistic Heavy Ion Collider

Neutron emission in electromagnetic dissociation of ultrarelativistic Pb ions

Contact Info

Product

Resources

About

Measurement of Mutual Coulomb Dissociation insNN=130GeV
M. Chiu
¹
,
A. Denisov
²
,
E. Oliver Garcia
³

et al.