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Related papers: Chiral corrections to $\pi^-\gamma\to 3\pi$ proces…

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We study production of photons via the non-equilibrium relaxation of a Disoriented Chiral Condensate with the chiral order parameter having a large initial amplitude along the \pi^0 direction. Assuming the validity of the low energy…

High Energy Physics - Phenomenology · Physics 2011-04-15 D. Boyanovsky , H. J. de Vega , R. Holman , S. Prem Kumar

We discuss a dynamical mechanism of pion production from disoriented chiral condensates (DCC). It leads to an explosive production of pions via the parametric amplification mechanism, which is similar to the reheating mechanism in…

High Energy Physics - Phenomenology · Physics 2009-10-31 Hideaki Hiro-Oka , Hisakazu Minakata

The weak decays $K^\pm\to\pi^\pm a$ offer a powerful probe of axion-like particles (ALPs). In this work, we provide a comprehensive analysis of these processes within chiral perturbation theory, extending existing calculations by including…

High Energy Physics - Phenomenology · Physics 2024-08-16 Claudia Cornella , Anne Mareike Galda , Matthias Neubert , Daniel Wyler

We give predictions for the partial wave amplitudes of pion photoproduction near threshold by means of dispersion relations at fixed t. The free parameters of this approach are determined by a fit to experimental data in the energy range…

Nuclear Theory · Physics 2016-09-08 O. Hanstein , D. Drechsel , L. Tiator

The in-medium pion properties, {\it i.e.} the temporal pion decay constant $f_t$, the pion mass $m_\pi^*$ and the wave function renormalization, in symmetric nuclear matter are calculated in an in-medium chiral perturbation theory up to the…

Nuclear Theory · Physics 2014-01-31 Soichiro Goda , Daisuke Jido

We make a thermal analysis of the light scalar susceptibilities using SU(3)-Chiral Perturbation Theory to one loop taking into account the QCD source of isospin breaking (IB), i.e corrections coming from $m_u\neq m_d$. The value of the…

High Energy Physics - Phenomenology · Physics 2015-06-03 R. Torres Andres , A. Gomez Nicola

We present a systematic analysis of next-to-next-to-leading-order diagrams that contribute to the $pp \to pp\pi^0$ production at threshold. Analytic expressions are given for the effective transition operators, and the relative importance…

Nuclear Theory · Physics 2008-11-26 V. Dmitrašinović , K. Kubodera , F. Myhrer , T. Sato

Forward photoproduction of $\pi^+\pi^-$ pairs with invariant mass of the order of $m_\rho\sim 770$ MeV is traditionally understood to be produced via Pomeron exchange. Based on a detailed analysis of the CLAS photoproduction data, it is…

We derive a novel chiral power counting scheme for in-medium chiral perturbation theory with explicit nucleonic and pionic degrees of freedom coupled to external sources. It allows for a systematic expansion taking into account local as…

Nuclear Theory · Physics 2009-12-08 J. A. Oller , A. Lacour , U. -G. Meißner

A calculation of the pion-production operator up to next-to-next-to-leading order for s-wave pions is performed within chiral effective field theory. In the previous study [Phys. Rev. C 85, 054001 (2012)] we discussed the contribution of…

Nuclear Theory · Physics 2013-12-16 A. A. Filin , V. Baru , E. Epelbaum , C. Hanhart , H. Krebs , F. Myhrer

The photon pair production by pion annihilation in a hot and dense medium at the chiral phase transition is investigated within a chiral quark model. As a direct consequence of this transition the $\sigma$ meson appears as a bound state in…

High Energy Physics - Phenomenology · Physics 2009-10-30 M. K. Volkov , E. A. Kuraev , D. Blaschke , G. Roepke , S. Schmidt

A general prescription for the construction of $\pi \pi$ interaction potentials which preserve scattering length constraints from chiral symmetry when iterated in scattering equations is derived. The prescription involves only minor…

Nuclear Theory · Physics 2009-10-28 R. Rapp , J. W. Durso , J. Wambach

A large set of cross sections for semi-inclusive electroproduction of charged pions ($\pi^\pm$) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared $W^2$ > 4…

After a brief introduction to chiral perturbation theory, the effective field theory of the standard model at low energies, two recent applications are reviewed: elastic pion-pion scattering to two-loop accuracy and the complete…

High Energy Physics - Phenomenology · Physics 2014-11-17 Gerhard Ecker

We show that, within a meson-exchange dynamical model describing most of the existing pion electromagnetic production data up to the second resonance region, one is also able to obtain a good agreement with the pi0 photo- and…

Nuclear Theory · Physics 2009-11-07 S. S. Kamalov , G. -Y. Chen , S. N. Yang , D. Drechsel , L. Tiator

I consider some selected topics in chiral perturbation theory (CHPT) as probed at colliders such as DA$\Phi$NE. Emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. These include the…

High Energy Physics - Phenomenology · Physics 2009-09-25 Ulf-G. Meißner

Using the close relationship between the low--energy constants of chiral perturbation theory and the chiral invariant interactions of the vector meson resonances with the pseudoscalar mesons, we investigate the process $\rho^0 \ra \pi^+…

High Energy Physics - Phenomenology · Physics 2009-10-28 K. Huber , H. Neufeld

We develop the formalism for coherent two pion photoproduction in nuclei and perform actual calculations of cross sections for $\pi^-\pi^+$ and $\pi^0\pi^0$ photoproduction on $^{12}C$. We find that due to the isospin symmetry the cross…

Nuclear Theory · Physics 2009-10-30 S. S. Kamalov , E. Oset

We present a calculation of the low energy constants describing the real and imaginary parts of the $K \to \pi \pi$ decay amplitudes $A_0$ and $A_2$. Leading and next leading order chiral perturbation theory is used and its applicability…

High Energy Physics - Lattice · Physics 2010-01-21 Shu Li , Norman H. Christ

We propose a formalism to extract the $\gamma\pi\to\pi\pi$ chiral anomaly $F_{3\pi}$ from calculations in lattice QCD performed at larger-than-physical pion masses. To this end, we start from a dispersive representation of the…

High Energy Physics - Phenomenology · Physics 2021-12-16 Malwin Niehus , Martin Hoferichter , Bastian Kubis