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We review the cross sections for low-energy $\pi^- \gamma$ reactions in the framework of chiral perturbation theory. Charged pion Compton scattering, $\pi^- \gamma\to \pi^-\gamma$, is considered up to one-loop order where the pion's…

Nuclear Theory · Physics 2008-11-26 N. Kaiser , J. M. Friedrich

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

The recently evaluated two-pion contribution to the muon g-2 and the phase of the pion electromagnetic form factor in the elastic region, known from \pi\pi scattering by Fermi-Watson theorem, are exploited by analytic techniques for finding…

High Energy Physics - Phenomenology · Physics 2011-05-13 B. Ananthanarayan , Irinel Caprini , I. Sentitemsu Imsong

We use 2HEX smeared gauge configurations generated with an $\mathrm{N}_\mathrm{f}\mathrm{=2+1}$ clover improved Wilson action to investigate $\pi\pi$ scattering in the $\rho$ channel. The range of lattice spacings (0.054 to 0.12 fm) and…

High Energy Physics - Lattice · Physics 2019-08-14 Thibaut Metivet

We calculate the combination $2a_0^{(0)}-5a_0^{(2)}$ (the Olsson sum rule) and the scattering lengths and effective ranges $a_1$, $a_2^{(I)}$ and $b_1$, $b_2^{(I)}$ dispersively (with the Froissart--Gribov representation) using, at low…

High Energy Physics - Phenomenology · Physics 2009-11-10 J. R. Pelaez , F. J. Yndurain

The H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F_pi) was extracted from the data by comparing the…

We have developed a field theory formalism to calculate $in$-$medium$ properties of hadrons within a unified approach that exploits a single Lagrangian to describe simultaneously both matter background and meson fluctuations. In this paper…

High Energy Physics - Phenomenology · Physics 2008-11-26 Hee-Jung Lee , Byung-Yoon Park , Mannque Rho , Vicente Vento

The low-energy chiral effective field theory of vector mesons and Goldstone bosons in external gravitational field is considered. The energy-momentum tensor is obtained and the gravitational form factors of the $\rho$-meson are calculated…

High Energy Physics - Phenomenology · Physics 2022-02-03 E. Epelbaum , J. Gegelia , U. -G. Meißner , M. V. Polyakov

We address the issue of a consistent power counting scheme in manifestly Lorentz-invariant baryon chiral perturbation theory. We discuss the inclusion of vector mesons in the calculation of the nucleon electromagnetic form factors. We…

High Energy Physics - Phenomenology · Physics 2008-11-26 S. Scherer

The partial width of the decay D^*+_s -> D^+_s pi^0 going through the violation of isotopical symmetry is computed with respect to the partial width of the radiative decay D^*+_s -> D^+_s gamma in the effective quark model with chiral…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. N. Ivanov

We study isospin-1 P-wave $\pi\pi$ scattering in lattice QCD with two flavours of O($a$) improved Wilson fermions. For pion masses ranging from $m_\pi=265$ MeV to $m_\pi=437$ MeV, we determine the energy spectrum in the centre-of-mass frame…

High Energy Physics - Lattice · Physics 2020-03-17 Felix Erben , Jeremy R. Green , Daniel Mohler , Hartmut Wittig

We evaluate the isospin breaking corrections to the scattering amplitude \pi^- K^+ -> \pi^- K^+ at threshold in the framework of chiral perturbation theory. This channel is of particular interest for the strong 2S-2P energy level shift in…

High Energy Physics - Phenomenology · Physics 2009-11-07 Bastian Kubis , Ulf-G. Meißner

Chiral effective field theory predicts a specific charge symmetry violating amplitude for pion production. This term is shown to provide the dominant contribution to the forward-backward asymmetry in the angular distribution for the…

Nuclear Theory · Physics 2011-02-01 U. van Kolck , J. A. Niskanen , G. A. Miller

The scalar radius of the pion plays an important role in CHPT, because it is related to one of the basic effective coupling constants, viz. the one which controls the quark mass dependence of F_pi at one loop. In a recent paper, Yndurain…

High Energy Physics - Phenomenology · Physics 2009-11-10 B. Ananthanarayan , I. Caprini , G. Colangelo , J. Gasser , H. Leutwyler

The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons…

High Energy Physics - Phenomenology · Physics 2014-11-17 J. L. Goity , W. Roberts

Chiral quark models with non-local covariant separable interactions at finite temperature and chemical potential are investigated. We develop a formalism in which the different quark properties are evaluated taking into account the analytic…

High Energy Physics - Phenomenology · Physics 2009-11-07 D. Gomez Dumm , N. N. Scoccola

We use chiral perturbation theory to study the extrapolations necessary to make physical predictions from lattice QCD data for the electromagnetic form factors of pseudoscalar mesons. We focus on the quark mass, momentum, lattice spacing,…

High Energy Physics - Lattice · Physics 2014-11-17 T. B. Bunton , F. -J. Jiang , B. C. Tiburzi

In the framework of heavy baryon chiral perturbation theory, we give thIn the framework of heavy baryon chiral perturbation theory, we give the chiral expansion for the $\pi N \to \pi \pi N$ threshold amplitudes $D_1$ and $D_2$ to quadratic…

High Energy Physics - Phenomenology · Physics 2009-10-28 V. Bernard , N. Kaiser , Ulf-G. Meißner

The interactions of $\rho$, $K^*$, $\phi$ and $\omega$ vector-mesons with low-momentum $\pi$, $K$ and $\eta$ pseudoscalar mesons are constrained by chiral symmetry. We derive a heavy vector-meson chiral Lagrangian in which the vector mesons…

High Energy Physics - Phenomenology · Physics 2008-11-26 Elizabeth Jenkins , Aneesh V. Manohar , Mark B. Wise

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