The Structure of the Neutral Current Coupling in High Energy Neutrino-Nucleon Interactions

Author: Merritt, Frank Smith

Year: 1977

Degree: Dissertation (Ph.D.)

Advisor: Barish, Barry C.

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/rtyt-zq54

Abstract

The primary objective of this experiment was to determine the Lorentz structure of the neutral current coupling -- that is, to determine what combination of V-A and V+A (or possibly S, P, and T) components make up the neutral coupling.

The experiment used the Fermilab narrow band neutrino beam to provide separated neutrino and antineutrino fluxes, each consisting of two energy bands at ≈55 and ≈150 Gev. Deep inelastic inclusive neutrino-nucleon interactions of the form

v(v) + N = µ-(µ+) + hadrons (CC event)

v(v) + N = v(v) + hadrons (NC event)

were observed in an instrumented steel target-calorimeter, which measured the total energy of the hadrons produced in each event. The neutral current coupling was determined by comparing the hadron energy distributions of neutrino and antineutrino neutral current events.

An analysis of the charged-current data was carried out in order to determine the background of charged-current events with unobserved muons, and to provide a normalization for the neutral current data. Various parameterizations of the CC interaction were tested, and their effects on the neutral current analysis were studied in detail.

The neutral current analysis indicates that, if only vector and axial-vector components exist, then the neutral current coupling lies between V and V-A. A pure scalar coupling is excluded. The data have been compared to the Weinberg-Salam theory (extended to semileptonic interactions), and are in very good agreement with its predictions. Comparison of this data to the low-energy Gargamelle data indicates consistency with a scaling hypothesis.

Files