Application of current-algebra techniques to soft-pion production by the weak neutral current: V, A cases

Journal Article · Sat Nov 01 04:00:00 EST 1975 · Phys. Rev., D, v. 12, no. 9, pp. 2644-2665

DOI:https://doi.org/10.1103/PhysRevD.12.2644· OSTI ID:4070497

Adler, S L

We apply current-algebra techniques to study the constraints imposed on neutral-current-induced soft-pion production, using as input existing bounds on neutrino-proton elastic scattering and existing data on neutral-current-induced deep-inelastic scattering. In the case of a purely isoscalar weak neutral current, a simple soft-pion argument relates the cross section for threshold (in pion--nucleon invariant mass) weak pion production directly to the cross section for neutrino--proton elastic scattering. Hence, a bound on the latter cross section implies a bound on the former. A previous model for weak pion production in the (3,3) resonance region is extended to include low-energy theorem constraints. Numerical work using the extended model shows that a threshold peak in preliminary data on $nu$ + n $Yields$ $nu$ + p + $pi$$sup -$ would have implied a threshold cross section much larger than can be obtained with any neutral current formed solely from members of the usual V, A nonets. We analyze recent results for neutral-current-induced soft-pion production under the simplifying assumption of a purely isoscalar V, A neutral current. We find in this case that the magnitude of the observations exceeds the theoretical maximum by more than a factor of 2 unless the assumed isoscalar current either contains a vector part with an anomalously larger gyromagnetic ratio or involves the ninth (SU$sub 3$ singlet) axial-vector current. A vector part with a large g value leads to characteristic modifications in the pion--nucleon invariant-mass spectrum for M($pi$N) less than or equals to 1.4 GeV. Two other qualitative predictions of isoscalar V, A structures are presented. (AIP)

• Research Organization: The Institute for Advanced Study, Princeton, New Jersey 08540
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-021420
• OSTI ID: 4070497
• Journal Information: Phys. Rev., D, v. 12, no. 9, pp. 2644-2665, Journal Name: Phys. Rev., D, v. 12, no. 9, pp. 2644-2665; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

*NEUTRINO-NUCLEON INTERACTIONS-- WEAK NEUTRAL CURRENTS
*PIONS-- PARTICLE PRODUCTION
641103*
BOUNDARY CONDITIONS
COUPLING
CROSS SECTIONS
CURRENT ALGEBRA
DELTA-1236 RESONANCES
DISPERSION RELATIONS
LOW-ENERGY THEOREM
N64230* --Physics (High Energy)--Particle Interactions & Properties (Theoretical)--Weak
SU-3 GROUPS
V-A THEORY