Breakdown of PCAC in diffractive neutrino interactions

Understand

We test the hypothesis of partially conserved axial current (PCAC) in high energy diffractive neutrino production of pions.

• Since the pion pole contribution to the Adler relation (AR) is forbidden by conservation of the lepton current, the heavier states, like the a_1 pole, \rho-\pi-cut, etc., control the lifetime of the hadronic fluctuations of the neutrino.
• We evaluate the deviation from the AR in diffractive neutrino-production of pions on proton and nuclear targets.
• At high energies, when all the relevant time scales considerably exceed the size of the target, the AR explicitly breaks down on an absorptive target, such as a heavy nucleus.