Some time after my retirement I started a scientific collaboration with Lalit Sehgal. Our interest in neutrino reactions led to the follwing publications: Lepton mass effects in single pion production by neutrinos (Physical Review D76, 113004, 2007), Partially conserved axial vector current and coherent pion production by low energy neutrinos. (Physical Review D79, 059003, 2009) and PCAC and coherent pion production by neutrinos. (arXiv:0908.2758, talk presented at NUINT09).
In addition we discussed CP violation in heavy (and not so heavy) quark systems deriving a novel upper bound in addition to the well known unitarity bound: CP violation and arrows of time: Evolution of a neutral K or B meson from an incoherent to a coherent state. (Physical Review D76, 036003, 2007) and Flow of entropy in the violition of the B0 B0 system: Upper bound of CP violation from unidirectionality: (Physical Review D86 057901, 2012). The new sort of unitarity bound obtained in these papers was applied to an interesting result from Fermilab concerning the decay of B quarks into „like sign“ dimuon pairs: Upper limit on CP violation in the B0 B0 system. (Physical Review D83, 037901, 2011).