Study of rare hadronic Lambda_b decays at LHCb.

The rare hadronic decays of heavy hadrons containing b quark have been extensively used to test Standard model of particle physics and search for possible effects of new physics. With datasets collected by the LHCb experiment, tests of the Standard model are now possible also with baryon decays, but up to now such studies are rather limited. Specifically, decays Lambda_b -> Lambda h h' with h and h' being charged pion or kaon has been observed by the LHCb using Run 1 data collected in 2011 and 2012 and CP asymmetry for Lambda_b -> Lambda K+ pi- and Lambda_b -> Lambda K+ K- decays has been found consistent with zero within large uncertainties. Since early LHCb result, data collected during Run 2 provides large increase of statistics. Additionally, the LHCb detector has been upgraded and is planned to run at about 5 times higher instantaneous luminosity over next couple of years. During upgrade, hardware trigger has been removed in order to increase trigger efficiency for fully hadronic decays like Lambda_b -> Lambda h h' .

In this project we plan to exploit already existing LHCb dataset together with data collected during Run 3 to update existing measurements on Lambda_b -> Lambda h h' decays. Besides measuring branching fractions and CP asymmetries over whole available phase-space of the decay we will also explore localised CP asymmetries. For this purpose, we plan to use both model independent methods as well as model dependent method through amplitude analysis of the decay. The localised CP asymmetries provide more sensitive way to test the Standard model as the observable CP asymmetry requires non-zero strong phases, which vary significantly over available phase-space of the decay. The results of this project will provide most sensitive measurement of the CP asymmetry in 3-body charmless Lambda_b decays and offer information complementary to that obtained from studies in the b-meson decays.