Form factor models and chiral symmetry

1970 ◽  
Vol 3 (8) ◽  
pp. 229-234 ◽  
Author(s):  
P. H. Frampton
Keyword(s):  
Form Factor ◽  
Chiral Symmetry ◽  
Factor Models

scholarly journals Pseudoscalar pole contribution to the hadronic light-by-light piece of aμ

2018 ◽  
Vol 192 ◽  
pp. 00027
Author(s):  
Adolfo Guevara ◽  
Pablo Roig ◽  
Juan José Sanz Cillero
Keyword(s):  
Form Factor ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Form Factors ◽  
Effective Field ◽  
Pole Contribution ◽  
Symmetry Relations ◽  
The Impact ◽  
Best Fit ◽  
Momentum Region

We have studied the P → γ⋆ γ⋆ form factor in Resonance Chiral Theory, with P = π0; η, η', to compute the contribution of the pseudoscalar pole to the hadronic light-by-light piece of the anomalous magnetic moment of the muon. In this work we allow the leading U(3) chiral symmetry breaking terms, obtaining the most general expression for the form factor of order O(m2P). The parameters of the Effective Field Theory are obtained by means of short distance constraints on the form factor and matching with the expected behavior from QCD. Those parameters that cannot be fixed in this way are fitted to experimental determinations of the form factor within the spacelike momentum region of the virtual photon. Chiral symmetry relations among the transition form factors for π0, η and η' allow for a simultaneous fit to experimental data for the three mesons. This shows an inconsistency between the BaBar π0 data and the rest of the experimental inputs. Thus, we find a total pseudoscalar pole contribution of aP,HLbLη = (8:47 ± 0:16) · 10-10 for our best fit (neglecting the BaBar π0 data). Also, a preliminary rough estimate of the impact of NLO in 1=NC corrections and higher vector multiplets (asym) enlarges the uncertainty up to aP,HLbLη = (8:47 ± 0:16stat ± 0:09NC +0:5 -0:0asym).

Two-nucleon transfer reactions with form factor models

1983 ◽  
Vol 73 (1) ◽  
pp. 27-36 ◽  
Author(s):  
A. Osman
Keyword(s):  
Form Factor ◽  
Factor Models ◽  
Transfer Reactions ◽  
Nucleon Transfer

scholarly journals IMPACT OF DYNAMICAL CHIRAL SYMMETRY BREAKING ON MESON STRUCTURE AND INTERACTIONS

2011 ◽  
Vol 26 (03n04) ◽  
pp. 371-377 ◽  
Author(s):  
H. L. L. ROBERTS ◽  
L. CHANG ◽  
C. D. ROBERTS
Keyword(s):  
Form Factor ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Recent Progress ◽  
Chiral Symmetry Breaking ◽  
Pion Form Factor ◽  
Dynamical Chiral Symmetry Breaking ◽  
The Masses ◽  
The Impact

We provide a glimpse of recent progress in meson physics made via QCD's Dyson-Schwinger equations with: a perspective on confinement and dynamical chiral symmetry breaking (DCSB); a précis on the physics of in-hadron condensates; results for the masses of the π, σ, ρ, a1 mesons and their first-radial excitations; and an illustration of the impact of DCSB on the pion form factor.

NUCLEON σ-TERM AND THE CHIRAL LIMIT

2007 ◽  
Vol 16 (09) ◽  
pp. 2884-2888
Author(s):  
ISABELA P. CAVALCANTE ◽  
MANOEL R. ROBILOTTA ◽  
GABRIEL R. S. ZARNAUSKAS ◽  
J. SÁ BORGES
Keyword(s):  
Form Factor ◽  
Chiral Symmetry ◽  
Configuration Space ◽  
Chiral Limit ◽  
Pion Mass ◽  
Nucleon Mass ◽  
Scalar Form Factor ◽  
Scalar Form

The scalar form factor of the nucleon in configuration space as well as its σ-term were evaluated some time ago in the framework of chiral symmetry. We investigate their dependence on the pion mass, aiming at the behavior of the σ-term at the chiral limit. Using the results for light pions, the nucleon mass as a function of the pion mass is evaluated. We also present the results for the scalar form factor for heavy pions.

The effect of temperature on high-resolution TEM image contrast

1995 ◽  
Vol 53 ◽  
pp. 640-641
Author(s):  
T. Geipel ◽  
W. Mader ◽  
P. Pirouz
Keyword(s):  
Form Factor ◽  
Inelastic Scattering ◽  
Accurate Method ◽  
Waller Factor ◽  
Effect Of Temperature ◽  
Specimen Thickness ◽  
Influence Of Temperature ◽  
Debye Waller Factor ◽  
Influence Of Temperature On ◽  
Atomic Form Factor

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

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