Speaker
Description
We discuss the production of $W^+ W^-$ pairs and $t \bar t$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including, for a first time, transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of $x$ and $Q^2$.
We focus on processes with single and double proton dissociation. Highly excited remnant systems hadronize producing particles that can be vetoed in the calorimeter. We calculate the associated effective gap survival factors. We observe approximate factorisation: $S_{R,DD} \approx S_{R,SD}^2$ when imposing rapidity veto. For the $W^+W^-$ final state, the remnant fragmentation leads to a taming of the cross section when the rapidity gap requirement is imposed. Also for $t \bar t$ quark-antiquark pairs such a condition reverses the hierarchy observed for the case when such condition is taken into account.
Our results imply that for the production of such heavy objects as $t$ quark and $\bar t$ antiquark the virtuality of the photons attached to the dissociative system are very large ($Q^2 <$ 10$^{4}$ GeV$^2$).
- M. Luszczak, L. Forthomme, W. Schafer, A. Szczurek,
arXiv:1810.12432; JHEP (2019) in print. - L. Forthomme, M. Luszczak, W. Schafer, A. Szczurek,
Phys.Lett. B789 (2019) 300-307. - M. Luszczak, W. Schafer, A. Szczurek,
JHEP 1805 (2018) 064.
