Anomaly-induced quadrupole moment of the neutron in magnetic field
Neutrons cannot possess a quadrupole moment in the vacuum. Nevertheless, we show that, in the presence of an external magnetic field, the neutrons acquire a new type of quadrupole moment Q{sup ij} = {chi}{sigma}{sup i} B{sup j} involving the components of spin and magnetic field. This 'chiral magnetic' quadrupole moment arises from the interplay of the chiral anomaly and the magnetic field; we estimate its value for the neutron in the static limit and find {chi} {approx_equal} 1.35 {center_dot} 10{sup -2} fm{sup 4}. The detection of the quadrupole moment of the neutron would provide a novel test of the role of the chiral anomaly in low-energy QCD and can be possible in the presence of both magnetic and inhomogeneous electric fields. The quadrupole moment of the neutron may affect, e.g., the properties of neutron stars and magnetars.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1034055
- Report Number(s):
- BNL-96329-2011-JA; R&D Project: PO-006; KB0301020; TRN: US1200718
- Journal Information:
- Physical Review. D, Particles, Fields, Gravitation and Cosmology, Vol. 84, Issue 3; ISSN 1550-7998
- Country of Publication:
- United States
- Language:
- English
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