Speaker
Description
High-multiplicity proton–proton and proton–lead collisions at LHC energies feature signatures similar to those observed in Pb--Pb collisions, such as e.g. strangeness enhancement and collective expansion effects, which are traditionally attributed to the formation of the quark–gluon plasma. One way to study them is through the measurement of $p_T$-spectra for identified hadrons such as charged $\pi$, $K$ and p, and the ratios of these spectra.
To date, analyses in ultra-peripheral collisions have mostly focused on exclusive photonuclear vector meson production and on two-photon interactions. However, photonuclear interactions, in which the target nucleus breaks up, also occur, and provide novel tests of collective phenomena in small systems. The $p_T$-spectra of identified pions, kaons and protons in these events have been measured by the ALICE experiment and compared to those obtained in other collision systems.
