Triple Regge exchange mechanisms of four-pion continuum production in the pp -> pp pi(+) pi(-) pi(+) pi(-) reaction

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Authors	KYCIA Radoslaw Antoni LEBIEDOWICZ Piotr SZCZUREK Antoni TURNAU Jacek
Year of publication	2017
Type	Article in Periodical
Magazine / Source	Physical review D
MU Faculty or unit	Faculty of Science
Citation
Web	https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.094020
Doi	http://dx.doi.org/10.1103/PhysRevD.95.094020
Keywords	triple Regge exchange mechanisms; four-pion continuum production
Description	We consider exclusive multiperipheral production of four charged pions in proton-proton collisions at high energies with simultaneous exchange of three Pomerons/Reggeons. The amplitude(s) for the genuine 2 -> 6 process are written in the Regge approach. The calculation is performed with the help of the GenEx Monte Carlo code. Some corrections at low invariant masses in the two-body subsystems are necessary for application of the Regge formalism. We estimate the corresponding cross section and present differential distributions in rapidity, transverse momenta and two- and four-pion invariant masses. The cross section and the distributions depend on the value of the cutoff parameter of a form factor correcting amplitudes for off-shellness of t-channel pions. A rather large cross section is found for the whole phase space (sigma similar to 1-5 mu b, including absorption corrections). Relatively large four-pion invariant masses are populated in the considered diffractive mechanism compared to other mechanisms discussed so far in the context of four-pion production. We investigate whether the triple Regge exchange processes could be identified with the existing LHC detectors. We consider the case of ATLAS and ALICE cuts. The ATLAS (or CMS) has a better chance to identify the process in the region of large invariant masses M-4 pi > 10 GeV. In the case of the ALICE experiment the considered mechanism competes with other mechanisms (production of sigma sigma, rho rho pairs or single resonances) and cannot be unambiguously identified.
Related projects:	Matematické struktury 6