Neutral pion photoproduction at threshold and explicit chiral symmetry breaking

T. Schäfer; W. Weise

doi:10.1016/0370-2693(90)91144-Z

Neutral pion photoproduction at threshold and explicit chiral symmetry breaking

T. Schäfer
, W. Weise

University of Regensburg

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

We investigate effects of explicit chiral symmetry breaking on the (γ,π⁰) amplitude at threshold (the photoproduction "sigma"- term) using a chiral bag model of the nucleon. We point out a strong connection between this term and the flavor singlet axial coupling constant g_A⁰ which measures the spin fraction carried by the quarks inside the nucleon. A comparison is made with recent experimental data which show deviations from the standard low energy theorem for photoproduction. The possible origin of this discrepancy is discussed on the basis of our calculations.

Original language	English
Pages (from-to)	6-10
Number of pages	5
Journal	Physics Letters B
Volume	250
Issue number	1-2
DOIs	https://doi.org/10.1016/0370-2693(90)91144-Z
State	Published - 1 Nov 1990
Externally published	Yes

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title = "Neutral pion photoproduction at threshold and explicit chiral symmetry breaking",

abstract = "We investigate effects of explicit chiral symmetry breaking on the (γ,π0) amplitude at threshold (the photoproduction {"}sigma{"}- term) using a chiral bag model of the nucleon. We point out a strong connection between this term and the flavor singlet axial coupling constant gA0 which measures the spin fraction carried by the quarks inside the nucleon. A comparison is made with recent experimental data which show deviations from the standard low energy theorem for photoproduction. The possible origin of this discrepancy is discussed on the basis of our calculations.",

author = "T. Sch{\"a}fer and W. Weise",

note = "Funding Information: \textasciitilde{}r Work supported in part by DFG grant We 665/9-3 and by BMFT grant 06 OR 762.",

year = "1990",

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doi = "10.1016/0370-2693(90)91144-Z",

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T1 - Neutral pion photoproduction at threshold and explicit chiral symmetry breaking

AU - Schäfer, T.

AU - Weise, W.

N1 - Funding Information: ~r Work supported in part by DFG grant We 665/9-3 and by BMFT grant 06 OR 762.

PY - 1990/11/1

Y1 - 1990/11/1

N2 - We investigate effects of explicit chiral symmetry breaking on the (γ,π0) amplitude at threshold (the photoproduction "sigma"- term) using a chiral bag model of the nucleon. We point out a strong connection between this term and the flavor singlet axial coupling constant gA0 which measures the spin fraction carried by the quarks inside the nucleon. A comparison is made with recent experimental data which show deviations from the standard low energy theorem for photoproduction. The possible origin of this discrepancy is discussed on the basis of our calculations.

AB - We investigate effects of explicit chiral symmetry breaking on the (γ,π0) amplitude at threshold (the photoproduction "sigma"- term) using a chiral bag model of the nucleon. We point out a strong connection between this term and the flavor singlet axial coupling constant gA0 which measures the spin fraction carried by the quarks inside the nucleon. A comparison is made with recent experimental data which show deviations from the standard low energy theorem for photoproduction. The possible origin of this discrepancy is discussed on the basis of our calculations.

UR - https://www.scopus.com/pages/publications/0040853958

U2 - 10.1016/0370-2693(90)91144-Z

DO - 10.1016/0370-2693(90)91144-Z

M3 - Article

AN - SCOPUS:0040853958

SN - 0370-2693

VL - 250

SP - 6

EP - 10

JO - Physics Letters B

JF - Physics Letters B

IS - 1-2

ER -

Neutral pion photoproduction at threshold and explicit chiral symmetry breaking

Abstract

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