Two-photon interactions with nuclear breakup in relativistic heavy ion collisions

Baltz, A. J.; Gorbunov, Y. N.; Klein, S. R.; Nystrand, J.

doi:10.1103/physrevc.80.044902

Cited by 83 publications

(109 citation statements)

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“…The transverse polarization dominates for ultrarelativistic particles (γ ≫ 1). Although this approach treats the nucleus as an idealistic hard sphere, the use of more realistic Woods-Saxon profiles gives effective γ γ luminosities only about 5% lower [51] than the hard-sphere approximation in the range of c.m. energies W γ γ ≈ 0.5 W max γ γ dominant in the exclusive production of an intermediate-mass Higgs boson.…”

Section: A Equivalent Photon Fluxesmentioning

confidence: 99%

Study of Higgs boson production and itsbb¯decay inγ−γprocesses in proton-nucleus collisions at the LHC

d’Enterria¹,

Lansberg²

2010

Phys. Rev. D

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We explore for the first time the possibilities to measure an intermediate-mass (m H = 115 -140 GeV/c 2 ) Standard-Model Higgs boson in electromagnetic proton-lead (p Pb) interactions at the CERN Large Hadron Collider (LHC) via its bb decay. Using equivalent Weizsäcker-Williams photon fluxes and Higgs effective field theory for the coupling γ γ → H, we obtain a leading-order cross section of the order of 0.3 pb for exclusive Higgs production in elastic (p Pb γ γ − − → p H Pb) and semielastic (p Pb γ γ − − → X H Pb) processes at √ s NN = 8.8 TeV. After applying various kinematics cuts to remove the main backgrounds (γ γ → bb and misidentified γ γ → qq events), we find that a Higgs boson with m H = 120 GeV/c 2 could be observed in the bb channel with a 3σ-significance integrating 300 pb −1 with an upgraded p A luminosity of 10 31 cm −2 s −1 . We also provide for the first time semielastic Higgs cross sections, along with elastic tt cross sections, for electromagnetic pp, p A and AA collisions at the LHC .

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Section: A Equivalent Photon Fluxesmentioning

confidence: 99%

Study of Higgs boson production and itsbb¯decay inγ−γprocesses in proton-nucleus collisions at the LHC

d’Enterria¹,

Lansberg²

2010

Phys. Rev. D

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“…Second, in the equivalent photon approximation we implicitly assumed zero virtuality for the photons. The STARlight calculation accounts for small photon virtualities, which results in a small ( 100 MeV) recoil of the γγ system against the ions themselves, see [22]. Third, in a large fraction of events the ion will end up in an excited state after the collision takes place, for instance through giant dipole resonances [23].…”

Section: The Photon-photon Luminositymentioning

confidence: 99%

Searching for Axionlike Particles with Ultraperipheral Heavy-Ion Collisions

et al. 2017

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We show that ultra-peripheral heavy-ion collisions at the LHC can be used to search for axionlike particles with mass below 100 GeV. The Z 4 enhanced photon-photon luminosity from the ions provides a large exclusive production rate, with a signature of a resonant pair of back-to-back photons and no other activity in the detector. In addition, we present both new and updated limits from recasting multi-photon searches at LEP II and the LHC, which are more stringent than those currently in the literature for the mass range 100 MeV to 100 GeV.

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“…[1] performed with the computer program Starlight [9] differed from the present calculation only in the use of an equivalent photon probability P ww ee (b) in Eq. (1) instead of the QED probability P ee (b).…”

mentioning

confidence: 99%

“…We have previously noted [9] that the requirement that final states be outside the nuclei may not be necessary for some final states such as lepton pairs. The smooth cutoff conventionally implemented by a momentum dependent form factor in QED calculations does not seem unreasonable.…”

mentioning

confidence: 99%

“…The Coulomb dissociation probability P 1x (b) and hadronic survival probabilities exp[−P nn (b)] were treated as described above identically in both calculations. The equivalent photon probability P ww ee (b) uses the Weizsacker-Williams photon spectrum calculated for the heavy ions and the Breit-Wheeler cross section for σ(γ + γ → e + e − ) [9]. In Starlight it is also required that photons originate only outside the nuclear radius R of each of the ions, and in the PHENIX calculations, a hard sphere radius R = 6.98 fm was used for this sharp cutoff.…”

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confidence: 99%

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Higher order QED in high-masse+e−pair production at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

Baltz

Nystrand

2010

Phys. Rev. C

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Lowest order and higher order QED calculations have been carried out for the RHIC high mass e + e − pairs observed by PHENIX with single ZDC triggers. The lowest order QED results for the experimental acceptance are about two standard deviations larger than the PHENIX data. Corresponding higher order QED calculations are within one standard deviation of the data. PACS: 25.75.-q, 34.90.+q A recent publication of the PHENIX collaboration at RHIC has presented data on ultraperipheral Au + Au photoproduction of the J/ψ and of continuum e + e − pairs in the invariant mass range of 2.0 -2.8 GeV/c 2 [1]. The present paper concerns itself not with the J/ψ but with the continuum pairs. A previous measurement of e + e − pairs at RHIC was carried out by the STAR colaboration in the somewhat lower invariant mass range 140 -265 MeV/c 2 [2], and it was subsequently argued that these data exhibited evidence for higher order QED effects [3]. This paper presents results of a higher order QED calculation for the PHENIX data using the same methodology as the calculations[3] previously published for the STAR data.The PHENIX data was presented as a differential cross section with respect to the pair equivalent mass m e + e − and the pair rapidity y pair with the constraint of at least one neutron detected in one of the zero degree calorimeters (ZDC): d 2 σ/dm e + e − dy pair (e + e − + Xn, y pair = 0). The differential cross section at y pair = 0 was taken from the sample |y pair | < 0.35 but with no constraint on pseudorapidity η of individual electrons and positrons. However, since the events measured by PHENIX detector had both the electron and positron pseudorapidities within |η| < 0.35, the stated results without the individual |η| < 0.35 were necessarily constructed from a model calculation. The PHENIX publication states, "The fraction of events with |(y pair )| < 0.35 and 2.0 < m e + e − < 2.8 GeV/c 2 , where both electron and positron are within |η| < 0.35 is 1.10%. The corresponding numbers for 2.0 < m e + e − < 2.3 GeV/c 2 and 2.3 < m e + e − < 2.8 GeV/c 2 are 1.11% and 1.08%, respectively." Since we wanted to carry out calculations closest to what PHENIX actually measured, here we calculate the cross sections with the electron and positron constraints |η| < 0.35 and compared with the cross sections in the PHENIX publication multiplied by 0.011, etc. (see also Ref. [4]).Following the method of the higher order calculations previously used for the STAR data, the cross sections here are computed from the product of the pair production probability P ee (b), the probability at least one of the ions Coulomb dissociating P 1x (b), and a survival factor exp[−P nn (b)] to exclude events where hadronic interactions occur(1)Unlike the STAR Coulomb dissociation factor P xx (b), which corresponds to neutrons detected in both ZDCs,here the corresponding Coulomb dissociation factor P 1x (b) is the unitarized probability that requires only that at least one of the colliding nuclei suffers Coulomb dissociationP C (b) the non-unitarized...

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Two-photon interactions with nuclear breakup in relativistic heavy ion collisions

Cited by 83 publications

References 44 publications

Study of Higgs boson production and itsbb¯decay inγ−γprocesses in proton-nucleus collisions at the LHC

Study of Higgs boson production and itsbb¯decay inγ−γprocesses in proton-nucleus collisions at the LHC

Searching for Axionlike Particles with Ultraperipheral Heavy-Ion Collisions

Higher order QED in high-masse+e−pair production at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

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