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).

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.

scholarly journals The impact of transverse Slavnov-Taylor identities on dynamical chiral symmetry breaking

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Luis Albino ◽  
Adnan Bashir ◽  
Bruno El-Bennich ◽  
Eduardo Rojas ◽  
Fernando E. Serna ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Limit ◽  
Chiral Symmetry Breaking ◽  
Form Factors ◽  
Coordinate Space ◽  
Scalar Form ◽  
Dynamical Chiral Symmetry Breaking ◽  
The Impact ◽  
Slavnov Taylor Identities

Abstract We extend earlier studies of transverse Ward-Fradkin-Green-Takahashi identities in QED, their usefulness to constrain the transverse fermion-boson vertex and their importance for multiplicative renormalizability, to the equivalent gauge identities in QCD. To this end, we consider transverse Slavnov-Taylor identities that constrain the transverse quark-gluon vertex and derive its eight associated scalar form factors. The complete vertex can be expressed in terms of the quark’s mass and wave-renormalization functions, the ghost-dressing function, the quark-ghost scattering amplitude and a set of eight form factors. The latter parametrize the hitherto unknown nonlocal tensor structure in the transverse Slavnov-Taylor identity which arises from the Fourier transform of a four-point function involving a Wilson line in coordinate space. We determine the functional form of these eight form factors with the constraints provided by the Bashir-Bermudez vertex and study the effects of this novel vertex on the quark in the Dyson-Schwinger equation using lattice QCD input for the gluon and ghost propagators. We observe significant dynamical chiral symmetry breaking and a mass gap that leads to a constituent mass of the order of 500 MeV for the light quarks. The flavor dependence of the mass and wave-renormalization functions as well as their analytic behavior on the complex momentum plane is studied and as an application we calculate the quark condensate and the pion’s weak decay constant in the chiral limit. Both are in very good agreement with their reference values.

scholarly journals Spontaneous and Controlled Macroscopic Chiral Symmetry Breaking by Means of Crystallization

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1796
Author(s):  
Gérard Coquerel ◽  
Marine Hoquante
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Operating Conditions ◽  
Temperature Cycle ◽  
Final State ◽  
Open Questions ◽  
The Impact ◽  
Kinetics Of ◽  
Influential Parameters

In this paper, macroscopic chiral symmetry breaking refers to as the process in which a mixture of enantiomers departs from 50–50 symmetry to favor one chirality, resulting in either a scalemic mixture or a pure enantiomer. In this domain, crystallization offers various possibilities, from the classical Viedma ripening or Temperature Cycle-Induced Deracemization to the famous Kondepudi experiment and then to so-called Preferential Enrichment. These processes, together with some variants, will be depicted in terms of thermodynamic pathways, departure from equilibrium and operating conditions. Influential parameters on the final state will be reviewed as well as the impact of kinetics of the R ⇔ S equilibrium in solution on chiral symmetry breaking. How one can control the outcome of symmetry breaking is examined. Several open questions are detailed and different interpretations are discussed.

scholarly journals Finite temperature Landau gauge lattice quark propagator

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Orlando Oliveira ◽  
Paulo J. Silva
Keyword(s):  
Wave Function ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Finite Temperature ◽  
Quark Mass ◽  
Chiral Symmetry Breaking ◽  
Form Factors ◽  
Landau Gauge ◽  
Quark Propagator ◽  
Quark Wave Function

Abstract The quark propagator at finite temperature is investigated using quenched gauge configurations. The propagator form factors are investigated for temperatures above and below the gluon deconfinement temperature $$T_c$$Tc and for the various Matsubara frequencies. Significant differences between the functional behaviour below and above $$T_c$$Tc are observed both for the quark wave function and the running quark mass. The results for the running quark mass indicate a link between gluon dynamics, the mechanism for chiral symmetry breaking and the deconfinement mechanism. For temperatures above $$T_c$$Tc and for low momenta, our results support also a description of quarks as free quasiparticles.

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