9th Workshop of the APS Topical Group on Hadronic Physics

Session

Ultra-Peripheral Collisions

Apr 16, 2021, 1:30 PM

Conveners

Ultra-Peripheral Collisions

• Dennis Perepelitsa (University of Colorado Boulder)

Description

co-host: Vincent Cheung

262. Probes of nuclei in ultra-peripheral collisions

Aleksandr Bylinkin (KU)

4/16/21, 1:30 PM

Oral Presentation

Ultra-peripheral collisions are the energy frontier for photon-mediated interactions, reaching, at the Large Hadron Collider (LHC), γ−p center of mass energies five to ten times higher than at HERA and reaching γγ energies higher than at LEP. Photoproduction of vector mesons and dijets in AA collisions probes the gluon distribution in the nuclei at Bjorken-x values down to 10−5, far smaller...

234. Accessing the gluon content of protons and nuclei in ultra peripheral collisions

Bjoern Schenke (Brookhaven National Lab)

4/16/21, 1:50 PM

Oral Presentation

Diffractive vector meson production in ultra-peripheral p+A and A+A collisions provides insight into the gluon distribution and its fluctuations in protons and heavier nuclei. I will present calculations of coherent and incoherent differential J/Psi cross sections within a dipole model and the Color Glass Condensate effective theory. We compute the energy/rapidity dependence of the fluctuating...

238. Measurements of long-range two-particle correlations in photo-proton and photo-nuclear collisions

Blair Seidlitz (University of Colorado at Boulder)

4/16/21, 2:10 PM

Oral Presentation

The ultra-peripheral collisions (UPCs) of relativistic ion beams lead to a prevalent and diverse set of photon-nucleus interactions in the case of Pb+Pb beams and photon-proton interactions in the case of $p$+Pb beams. The measurements of particles and their interactions produced in photo-nucleon reactions can shed light on the QCD dynamics of EM-induced, extremely asymmetric colliding...

217. New physics and tau g-2 using LHC heavy ion collisions

Lydia Beresford (CERN)

4/16/21, 2:30 PM

Oral Presentation

The electromagnetic moments of the tau lepton are highly sensitive to new physics but are challenging to measure due to the short tau lifetime. We propose a strategy using heavy ion collisions at the LHC as an intense source of photon collisions in order to surpass 15 year old lepton collider constraints on the tau anomalous magnetic moment. This exciting possibility could be achievable today...

251. Photon mediated processes from strong electromagnetic fields in theory and experiment

James Brandenburg (Brookhaven National Laboratory)

4/16/21, 2:50 PM

Oral Presentation

Ultra-relativistic heavy-ion collisions produce the strongest electromagnetic fields in the known Universe..
These highly-Lorentz contracted fields manifest themselves as linearly polarized quasi-real photons that can interact via the Breit-Wheeler process to produce lepton anti-lepton pairs. The energy and momentum distribution of the produced dileptons carry information about the strength...

253. UPC processes in non-UPC collisions

Soumya Mohapatra Mohapatra (Columbia University, Department of Physics)

4/16/21, 3:10 PM

Oral Presentation

Muon pairs produced via two-photon scattering processes in hadronic Pb+Pb collisions provide a potentially sensitive electromagnetic probe of the quark gluon plasma. First measurements by ATLAS and STAR of dileptons produced via two-photon scattering in non-ultra-peripheral (non-UPC) nucleus-nucleus collisions showed an unexpected centrality-dependent broadening of the angular correlation...