Aspects of near threshold neutral pion photoproduction off protons

Abstract

We investigate near threshold neutral pion photoproduction off protons to fourth order in heavy baryon chiral perturbation theory in the light of the new data from MAMI. We show that the unitarity cusp at the secondary π^+ n threshold is in agreement with expectations from the final state theorem. We also analyze the fourth order corrections to the P-wave low-energy theorems and show that potentially large Delta-isobar contributions are cancelled by sizeable pion loop effects. This solidifies the parameter free third order predictions, which are in excellent agreement with the data.

13 pp, LaTeX2e, updated version, using officially released data

Cited by in corpus (31)

• Threshold cusps and triangle singularities in hadronic reactions
• Chiral perturbation theory
• Photon- and pion-nucleon interactions in a unitary and causal effective field theory based on the chiral Lagrangian
• Photocouplings at the Pole from Pion Photoproduction
• Test of low-energy theorems for p(\vec{gamma},π^{0})p in the threshold region
• Accurate Test of Chiral Dynamics in the \boldmath$\vec{\gamma }p\to {\pi }^{0}p$ Reaction
• Model Selection for Pion Photoproduction
• Threshold ${\pi }^0$ photoproduction in relativistic chiral perturbation theory
• Upper Energy Limit of Heavy Baryon Chiral Perturbation Theory in Neutral Pion Photoproduction
• Improved analysis of neutral pion electroproduction off deuterium in chiral perturbation theory
• The Fubini-Furlan-Rosetti sum rule and related aspects in light of covariant baryon chiral perturbation theory
• Helicity asymmetries in double pion photoproduction on the proton
• The Fubini-Furlan-Rossetti Sum Rule Revisited
• Unexpected impact of D waves in low-energy neutral pion photoproduction from the proton and the extraction of multipoles
• Near threshold neutral pion electroproduction on deuterium in chiral perturbation theory
• Pion photoproduction off nucleons in covariant chiral perturbation theory
• $\Delta (1232)$ resonance in the $\vec{\gamma }p\to p{\pi }^0$ reaction at threshold
• Chiral Dynamics in Photo-Pion Physics: Theory, Experiment, and Future Studies at the HI$\gamma$S Facility
• Low-Energy D-Wave Effects in Neutral Pion Photoproduction
• Threshold pion electro- and photoproduction off nucleons in covariant chiral perturbation theory
• Chiral O(Q^4) two-body operators for s-wave pion photoproduction on the NN system
• Dispersive Analysis of Low Energy $\gamma N\to \pi N$ Process and Studies on the $N^{\ast }(890)$ Resonance
• Operator Approach to Isospin Violation in Pion Photoproduction
• Neutral pion photoproduction off 3H and 3He in chiral perturbation theory
• A dispersive approach to pion photo- and electroproduction
• Radiative pion photoproduction in covariant chiral perturbation theory
• Threshold neutral pion photoproduction off the tri-nucleon to O(q^4)
• Unification of the physics of nucleons and nuclei
• Neutral Pion Production in the Threshold Region
• A precision measurement of the $p$($e,e^{\prime }p$)${\pi }^0$ reaction at threshold
• Threshold Neutral Pion Photoproduction on the Proton