Speaker
Description
Light-by-Light scattering involves the interaction of two strong electromagnetic fields, resulting in the emission of two photons. The phenomenon was first observed experimentally in 2017 [1][2], using photon measurements in ultraperipheral lead-lead collisions (UPC). Applying the Equivalent Photon Approximation model gives results which describe differential and total cross sections presented by ATLAS and CMS Collaborations [3]. They have detected photons in midrapidity for $p_t > 2.5$ (ATLAS) and $p_t > 2$ GeV (CMS).
In the next few years, the ALICE 3 experiment [4] is going to measure photons in forward calorimeter (FoCal) [5], in the transverse momentum range $p_t$ = 1 - 50 MeV and 100 - 5000 MeV, which have not been investigated so far. Moving to a lower range of $p_t$ imposes a consideration of low-energy meson resonances which decay into two-photon channel. The first contribution from $\eta$, $\eta'$ mesons in UPC was studied in [6]. Research in the low $p_t$ area allows to verify the importance of pion. Furthermore, experimental possibilities to investigate the VDM-Regge mechanism [7] will be discussed. The role of the vertical background in light-by-light scattering measurements will also be shown.
Bibliography:
$[1]$ ATLAS Collaboration (M. Aaboud et al.), Nature Phys.13852 (2017)
$[2]$ CMS Collaboration, Phys. Lett. B797 (2019) 134826
$[3]$ G.K. Krintiras, I. Grabowska-Bold, M. Kłusek-Gawenda, É. Chapon, R. Chudasama, Acta Phys. Polon. Supp. 16 (2023) 1, 123
$[4]$ ALICE Collaboration, CERN-LHCC-2022-009, LHCC-I-038, arXiv:2211.02491 (2022)
$[5]$ ATLAS Collaboration, CERN-LHCC-2020-009, LHCC-I-036 (2020)
$[6]$ M. Kłusek-Gawenda, R. McNulty, R. Schicker, A. Szczurek, Phys. Rev. D99 (2019) 093013
$[7]$ M. Kłusek-Gawenda, P. Lebiedowicz, A. Szczurek, Phys. Rev. C93 (2016) 044907
