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Related papers: Unitary and causal dynamics based on the chiral La…

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We study the S-wave interaction of mesons with baryons in the strangeness S=0 sector in a coupled channel unitary approach. The basic dynamics is drawn from the lowest order meson baryon chiral Lagrangians. Small modifications inspired by…

High Energy Physics - Phenomenology · Physics 2011-02-09 T. Inoue , J. C. Nacher , M. J. Vicente Vacas , E. Oset

The general structure of the cross section of $\gamma N$ scattering with polarized photon and/or nucleon in initial and/or final state is systematically described and exposed through invariant amplitudes. A low-energy expansion of the cross…

High Energy Physics - Phenomenology · Physics 2009-09-25 D. Babusci , G. Giordano , A. I. L'vov , G. Matone , A. M. Nathan

In these lectures, the status of baryon chiral perturbation theory is reviewed. Particular emphasis is put on the two--flavor sector and the physics related to electromagnetic probes. I discuss in some detail the structure of the effective…

High Energy Physics - Phenomenology · Physics 2011-04-15 Ulf-G. Meißner

We show that chiral symmetry and gauge invariance enforce relations between the short-distance physics that occurs in a number of electroweak and pionic reactions on light nuclei. Within chiral perturbation theory this is manifested via the…

Nuclear Theory · Physics 2008-11-26 A. Gardestig , D. R. Phillips

We extend our previous study of elastic pion-nucleon scattering in the framework of chiral perturbation theory by performing a combined analysis of the reactions $\pi N \to \pi N$ and $\pi N \to \pi \pi N$. The calculation is carried out to…

Nuclear Theory · Physics 2020-03-05 D. Siemens , V. Bernard , E. Epelbaum , A. M. Gasparyan , H. Krebs , Ulf-G. Meißner

The S-matrix approach is used to calculate charged as well as neutral pion production reactions from NN scattering, with the same set of underlying processes and interactions. The chiral perturbation theory piN scattering amplitude is used.…

Nuclear Theory · Physics 2008-11-26 V. Malafaia , M. T. Pena , Ch. Elster , J. Adam

We construct an equation-of-state for nuclear matter based on the chiral Lagrangian. The relevant scales are discussed and an effective chiral power expansion scheme, which is constructed to work around the nuclear saturation density, is…

Nuclear Theory · Physics 2010-12-16 M. Lutz , B. Friman , Ch. Appel

The linear $\s$-model is used to study the effects of chiral symmetry in unitarized amplitudes incorporating scalar resonances. When just a single resonance is present, we show that the iteration of a chiral tree amplitude by means of…

Nuclear Theory · Physics 2007-05-23 L. O. Arantes , M. R. Robilotta

Threshold neutral pion photoproduction on the deuteron is studied in the framework of baryon chiral perturbation theory beyond next-to--leading order in the chiral expansion. To fourth order in small momenta, the amplitude is finite and a…

High Energy Physics - Phenomenology · Physics 2009-10-30 S. R. Beane , V. Bernard , T. -S. H. Lee , Ulf-G. Meißner , U. van Kolck

Low lying scalar resonances emerge as a necessary part to adjust chiral perturbation theory to experimental data once unitarity constraint is taken into consideration. I review recent progress made in this direction in a model independent…

High Energy Physics - Phenomenology · Physics 2009-05-06 Han-qing Zheng

We have developed a relativistic point-coupling model of nuclear many-body dynamics constrained by the low-energy sector of QCD. The effective Lagrangian is characterized by density-dependent coupling strengths determined by chiral one- and…

Nuclear Theory · Physics 2017-08-23 Paolo Finelli , Norbert Kaiser , Dario Vretenar , Wolfram Weise

In recent years, detailed studies of three-pion systems have become possible in lattice QCD. This has in turn led to interest in 3-to-3 scattering of pions in the chiral perturbation theory framework. In addition to being an interesting…

High Energy Physics - Phenomenology · Physics 2023-10-12 Jorge Baeza-Ballesteros , Johan Bijnens , Tomáš Husek , Fernando Romero-López , Stephen R. Sharpe , Mattias Sjö

We construct the most general low-energy effective lagrangian including local parity violating terms parametrized by an axial chemical potential or chiral imbalance $\mu_5$, up to ${\cal O}(p^4)$ order in the chiral expansion for two light…

High Energy Physics - Phenomenology · Physics 2020-07-15 Domènec Espriu , Angel Gómez Nicola , Andrea Vioque-Rodríguez

We derive a representation for the pion nucleon scattering amplitude that is valid to the fourth order of the chiral expansion. To obtain the correct analytic structure of the singularities in the low energy region, we have performed the…

High Energy Physics - Phenomenology · Physics 2010-02-03 T. Becher , H. Leutwyler

We apply the perturbative chiral quark model to the study of the low-energy pi-N interaction. Using an effective chiral Lagrangian we reproduce the Weinberg-Tomozawa result for the S-wave pi-N scattering lengths. After inclusion of the…

High Energy Physics - Phenomenology · Physics 2009-11-07 V. E. Lyubovitskij , Th. Gutsche , Amand Faessler , R. Vinh Mau

We present a study of the $\pi\pi$ scattering amplitude in the $\sigma$ and $\rho$ channels at finite temperature and nuclear density within a chiral unitary framework. Meson resonances are dynamically generated in our approach, which…

High Energy Physics - Phenomenology · Physics 2009-07-22 D. Cabrera , D. Fernandez-Fraile , A. Gomez Nicola

Photo- and electroproduction of eta, eta-prime mesons on protons are investigated within a relativistic chiral unitary approach based on coupled channels. The s wave potentials for electroproduction and meson-baryon scattering are derived…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. Borasoy , E. Marco , S. Wetzel

Low-energy Compton scattering off the proton is used for determination of the proton polarizabilities. However, the present empirical determinations rely heavily on the theoretical description(s) of the experimental cross sections in terms…

Nuclear Theory · Physics 2018-05-21 Nadiia Krupina , Vadim Lensky , Vladimir Pascalutsa

We calculate the s-wave part of the pion-nucleus optical potential using a unitarized chiral approach that has been previously used to simultaneously describe pionic hydrogen and deuterium data as well as low energy pi N scattering in the…

Nuclear Theory · Physics 2008-11-26 M. Doring , E. Oset

An explicitly crossing-symmetric decomposition of the pion-pion scattering amplitudes into low- and high-energy components is established. The high-energy components are entirely determined by absorptive parts at high energies. With the…

High Energy Physics - Phenomenology · Physics 2007-05-23 G. Wanders