Speaker
Description
Photon-induced processes in proton-proton interactions have become
recently very topical. The large energy at the LHC, when combined with
relatively large luminosity at run II, allows starting the exploration of such processes.
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. The gap survival factors depend on the process, the mass
of the remnant system and collision energy.
The rapidity gap survival factor due to remnant fragmentation for double
dissociative (DD) collisions is smaller than that for single
dissociative (SD) process.
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$^2$). A similar effect was observed for the $W^+ W^-$ system.
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M. Luszczak, L. Forthomme, W. Schafer, A. Szczurek,
JHEP 1902 (2019) 100. -
L. Forthomme, M. Luszczak, W. Schafer, A. Szczurek,
Phys.Lett. B789 (2019) 300-307. -
M. Luszczak, W. Schafer, A. Szczurek,
JHEP 1805 (2018) 064. -
M. Luszczak, W. Schafer and A. Szczurek,
Phys. Rev. D93 (2016) 7, 074018. -
M. Luszczak, A. Szczurek, Ch. Royon,
JHEP 1502 (2015) 098.
