Lorentz- and CPT-violating standard model extension in chiral perturbation theory

• Published in: Physical review. D 2019-10, Vol.100 (7), p.075031-1
• Main Authors: Altschul, Brett, Schindler, Matthias R
• Format: Article
• Language: English
• Subjects: Astronomy & Astrophysics; Baryons; Chiral dynamics; Gluons; Level (quantity); Mapping; Mathematical models; Operators (mathematics); Partons; Perturbation methods; Perturbation theory; Physics; Quarks; Standard model (particle physics); Translations
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.100.075031

Lorentz and CPT violation in hadronic physics must be tied to symmetry violations at the underlying quark and gluon level. Chiral perturbation theory provides a method for translating novel operators that may appear in the Lagrange density for color-charged parton fields into equivalent forms for effective theories at the meson and baryon levels. We extend the application of this technique to the study of Lorentz-violating and potentially CPT-violating operators from the minimal standard model extension. For dimension-4 operators, there are nontrivial relations between the coefficients of baryon-level operators related to underlying quark and gluon operators with the same Lorentz structures. Moreover, in the mapping of the dimension-3 operators from the quark and gluon level to the hadron level (considered here for the first time), many of the hadronic observables contain no new low-energy coupling constants at all, which makes it possible to make direct translations of bounds derived using experiments on one kind of hadron into bounds in a completely different corner of the hadronic sector. A notable consequence of this is bounds (at 10−15 − 10−20 GeV levels) on differences aBμ − aB′μ of Lorentz and CPT violation coefficients for SU(3)f octet baryons that differ in their structure by the replacement of a single valance d quark by a s quark. Never before has there been any proposal for how these kinds of differences could be constrained.