scholarly journals The strange quark contribution to the proton's magnetic moment

2004 ◽  
Vol 583 (1-2) ◽  
pp. 79-86 ◽  
Author(s):  
D.T Spayde ◽  
D.H Beck ◽  
R Hasty ◽  
T Averett ◽  
D Barkhuff ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Strange Quark ◽  
Quark Contribution

scholarly journals QUARK STARS AND QUANTUM-MAGNETICALLY INDUCED COLLAPSE

2005 ◽  
Vol 14 (11) ◽  
pp. 1959-1969 ◽  
Author(s):  
A. PÉREZ MARTÍNEZ ◽  
H. PÉREZ ROJAS ◽  
H. J. MOSQUERA CUESTA ◽  
M. BOLIGAN ◽  
M. G. ORSARIA
Keyword(s):  
Neutron Stars ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Quark Matter ◽  
Strange Quark ◽  
Vacuum Energy Density ◽  
Bag Model ◽  
X Ray ◽  
Quark Stars ◽  
Mit Bag Model

Quark matter is expected to exist in the interior of compact stellar objects as neutron stars or even the more exotic strange stars, based on the Bodmer–Witten conjecture. Bare strange quark stars and (normal) strange quark-matter stars, those possessing a baryon (electron-supported) crust, are hypothesized as good candidates to explain the properties of a set of peculiar stellar sources such as the enigmatic X-ray source RX J1856.5-3754, some pulsars such as PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft γ-ray repeaters. In the MIT bag model, quarks are treated as a degenerate Fermi gas confined to a region of space having a vacuum energy density B bag (the Bag constant). In this note, we modify the MIT bag model by including the electromagnetic interaction. We also show that this version of the MIT model implies the anisotropy of the bag pressure due to the presence of the magnetic field. The equations of state of the degenerate quarks gases are studied in the presence of ultra strong magnetic fields. The behavior of a system made up of quarks having (or not) anomalous magnetic moment is reviewed. A structural instability is found, which is related to the anisotropic nature of the pressures in this highly magnetized matter. The conditions for the collapse of this system are obtained and compared to a previous model of neutron stars that is built on a neutron gas having anomalous magnetic moment.

scholarly journals Heavy-quark contribution to the proton's magnetic moment

2007 ◽  
Vol 647 (5-6) ◽  
pp. 361-365 ◽  
Author(s):  
Xiangdong Ji ◽  
D. Toublan
Keyword(s):  
Heavy Quark ◽  
Magnetic Moment ◽  
Quark Contribution

scholarly journals Hadronic Leading Order Contribution to the Muon g-2

2018 ◽  
Vol 179 ◽  
pp. 01016
Author(s):  
Daisuke Nomura
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Leading Order ◽  
Muon Anomalous Magnetic Moment ◽  
Order Contribution ◽  
Quark Contribution ◽  
The Standard Model ◽  
Vacuum Polarisation

We calculate the Standard Model (SM) prediction for the muon anomalous magnetic moment. By using the latest experimental data for e+e- → hadrons as input to dispersive integrals, we obtain the values of the leading order (LO) and the next-to-leading-order (NLO) hadronic vacuum polarisation contributions as ahad, LO VPμ = (693:27 ± 2:46) × 10-10 and ahad, NLO VP μ = (_9.82 ± 0:04) × 1010-10, respectively. When combined with other contributions to the SM prediction, we obtain aμ(SM) = (11659182:05 ± 3.56) × 10-10; which is deviated from the experimental value by Δaμ(exp) _ aμ(SM) = (27.05 ± 7.26) × 10-10. This means that there is a 3.7 σ discrepancy between the experimental value and the SM prediction. We also discuss another closely related quantity, the running QED coupling at the Z-pole, α(M2 Z). By using the same e+e- → hadrons data as input, our result for the 5-flavour quark contribution to the running QED coupling at the Z pole is Δ(5)had(M2 Z) = (276.11 ± 1.11) × 10-4, from which we obtain Δ(M2 Z) = 128.946 ± 0.015.

ASYMMETRIES IN POLARIZED ELECTRON SCATTERING AND THE STRANGENESS CONTENT OF THE NUCLEON

2009 ◽  
Vol 24 (11n13) ◽  
pp. 881-886
Author(s):  
SEBASTIAN BAUNACK
Keyword(s):  
Electron Scattering ◽  
Strange Quark ◽  
Form Factors ◽  
Strange Quarks ◽  
Quark Contribution ◽  
Nucleon Form Factors ◽  
Strangeness Content ◽  
Existing Data

In the viewpoint of QCD, the nucleon is made up of constituent quarks, sea quarks and gluons. Concerning the quark sea, also strange quarks can contribute to the nucleon properties. Parity violating electron scattering offers a tool to investigate the strange quark contribution to the nucleon form factors. The measurements of different experiments are discussed and the recent results from the A4 collaboration at MAMI is presented. Altogether the existing data allow to give constraints on the strangeness contribution.

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