Electromagnetic structure of decuplet baryons towards the chiral regime

Journal Article · Tue Sep 01 00:00:00 EDT 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.80.054505· OSTI ID:21322609

Boinepalli, S; Leinweber, D B; Moran, P J; Williams, A G ^[1]; Zanotti, J M ^[2]; Zhang, J B ^[3]

---

1. Department of Physics and Mathematical Physics and Special Research Centre for the Subatomic Structure of Matter, University of Adelaide, 5005 (Australia)
2. School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)
3. Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a 20{sup 3}x40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-3/2 baryons, including the electric-quadrupole moment E2 and the magnetic-octupole moment M3. The world's first determination of a nonzero M3 form factor for the {delta} baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish that the environment sensitivity is far less pronounced for the decuplet baryons compared to the octet baryons. A surprising result is that the charge radii of the decuplet baryons are generally smaller than those of the octet baryons. The magnetic moment of the {delta}{sup +} reveals a turnover in the low quark-mass region, making it smaller than the proton magnetic moment. These results are consistent with the expectations of quenched chiral perturbation theory. A similar turnover is also noticed in the magnetic moment of the {sigma}*{sup 0}, but not for {xi}* where only kaon loops can appear in quenched QCD. The electric-quadrupole moment of the {omega}{sup -} baryon is positive when the negative charge factor is included, and is equal to 0.86{+-}0.12x10{sup -2} fm{sup 2}, indicating an oblate shape.

• OSTI ID: 21322609
• Journal Information: Physical Review. D, Particles Fields, Vol. 80, Issue 5; Other Information: DOI: 10.1103/PhysRevD.80.054505; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
CHIRALITY
COMPARATIVE EVALUATIONS
E2-TRANSITIONS
FORM FACTORS
KAONS
M3-TRANSITIONS
MAGNETIC FORMING
MAGNETIC MOMENTS
MASS
MEV RANGE 100-1000
OCTUPOLES
OMEGA MINUS PARTICLES
PERTURBATION THEORY
PIONS
PROTONS
QUADRUPOLE MOMENTS
QUANTUM CHROMODYNAMICS
QUARKS
SIGMA MINUS PARTICLES
SPIN
XI MINUS PARTICLES