Recent CMS results from gamma-gamma and gamma-p interactions in UPC
will be reviewed.
Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons,
leading to multiple photon-induced processes. This talk presents a series of measurements of such
processes performed by the ATLAS Collaboration. New measurements of exclusive dilepton production
(electron, muon, and tau pairs) are discussed. Furthermore, the tau-pair production measurements
can...
The Precision Proton Spectrometer (PPS) is a new subdetector of CMS introduced for the LHC Run 2. The talk will present the recent results on photon-induced processes explored with PPS, illustrating the unique sensitivity which can be achieved using proton tagging.
We describe the gain on sensitivities to quartic πΎπΎπΎπΎ, πΎπΎππ and πΎπΎπΎπ anomalous couplings and to the search for Axion-Like Particles by two or three orders of magnitude with respect to standard methods at the LHC by tagging intact protons in the final state, and matching the information from the intact protons and the ππ, ππ, πΎπ, πΎπΎ in the main CMS and ATLAS detectors. We will also describe the...
Till recently, light-by-light scattering ($\gamma \gamma \to \gamma \gamma$) was not accessible for experiments because the corresponding cross section is relatively low. Measurements of diphotons in ultra-peripheral collisions (UPCs) of lead-lead nuclei have been reported recently by the ATLAS and CMS Collaborations. Our theoretical results [1] based on the equivalent photon approximation in...
Studies of vector meson exclusive production in pp collisions will be discussed. At the LHC energy, measurements of diffractive events probe interesting QCD phenomenology, including the nature of pomerons, low-x gluon distributions and saturation effects.
Photon-photon and photonuclear reactions are induced by the strong electromagnetic fields generated by ultrarelativistic heavy-ion collisions. These processes have been extensively studied in ultra-peripheral collisions with impact parameters larger than twice the nuclear radii. Photoproduced quarkonia can probe the nuclear gluon distributions at low Bjorken-x. The continuum dilepton...
Measurements of quarkonia production in peripheral and ultra-peripheral heavy-ion collisions are sensitive to photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and the mechanisms of vector-meson production. LHCb has studied both coherent and incoherent production of π½/π mesons in peripheral and ultra-peripheral collisions using PbPb data at forward rapidity with...
We present a detailed study of transition form factors for axial-vector meson production via the two-photon fusion process $\gamma^* \gamma^* \to 1^{++}$, with space-like virtual photons in the initial state and a $P$-wave axial-vector quarkonium in the final state. In this analysis, we employ the formalism of light-front quarkonium wave functions obtained from a solution of the Schr\"odinger...
Many standard model processes in proton-proton collisions at the LHC are produced through diffractive interactions where one or both protons may survive the collisions. The dominant production of diffractive interactions is where only one proton emerges intact (hard single diffraction). We propose using the LHC data to study the diffractive production of EW boson and heavy flavor quarks as a...
