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The chiral expansion of nucleon properties such as mass, magnetic moment, and magnetic polarizability are investigated in the framework of chiral perturbation theory, with and without the heavy-baryon expansion. The analysis makes use of a…

High Energy Physics - Phenomenology · Physics 2014-11-21 J. M. M. Hall , V. Pascalutsa

In a small window of phase space, chiral perturbation theory can be used to make standard model predictions for tau decays into two and three pions. For $\tau \to 2\pi \nu_\tau$, we give the analytical result for the relevant form factor…

High Energy Physics - Phenomenology · Physics 2009-10-28 G. Colangelo , M. Finkemeier , R. Urech

We study pion--nucleon scattering with a chiral lagrangian of pions, nucleons, and $\Delta$-isobars. The scattering amplitude is evaluated to one-loop $Q^3$ order, where $Q$ is a generic small momentum, using a new approach which is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Paul J. Ellis , Hua-Bin Tang

We study the pion velocity near the critical temperature $T_c$ of chiral symmetry restoration in QCD. Using chiral perturbation theory based on hidden local symmetry (HLS) as an effective field theory, where the chiral symmetry restoration…

High Energy Physics - Phenomenology · Physics 2007-05-23 Masayasu Harada , Mannque Rho , Chihiro Sasaki

We investigate the properties of the pion quasiparticle in the low-temperature phase of two-flavor QCD on the lattice with support from chiral effective theory. We find that the pion quasiparticle mass is significantly reduced compared to…

High Energy Physics - Lattice · Physics 2015-11-18 Bastian B. Brandt , Anthony Francis , Harvey B. Meyer , Daniel Robaina

We compute the scattering amplitude for pion scattering in Wilson chiral perturbation theory for two degenerate quark flavors. We consider two different regimes where the quark mass m is of order (i) a\Lambda_QCD^2 and (ii)…

High Energy Physics - Lattice · Physics 2009-04-13 Sinya Aoki , Oliver Bar , Benedikt Biedermann

We investigate the modification of the pion self-energy at finite temperature due to its interaction with a low-density, isospin-symmetric nuclear medium embedded in a constant magnetic background. To one loop, for fixed temperature and…

Nuclear Theory · Physics 2013-12-10 Giuseppe Colucci , Eduardo S. Fraga , Armen Sedrakian

The speed of cool pions in the chiral limit is analytically computed at low temperature within the imaginary time formalism to two loop order. This evaluation shows a logarithmic dependence in the temperature where the scale within the…

High Energy Physics - Phenomenology · Physics 2016-08-25 J. M. Martinez Resco , M. A. Valle Basagoiti

I discuss recent progress in our understanding of the pi pi scattering amplitude at low energy thanks to the combined use of chiral perturbation theory and dispersion relations. I also comment on the criticism raised by Pelaez and Yndurain…

High Energy Physics - Phenomenology · Physics 2009-11-11 Gilberto Colangelo

We present the results on the relativistic six-pion scattering amplitude at low energy, calculated at $\mathcal{O}(p^4)$ within the framework of the massive $\text{O}(N)$ nonlinear sigma model extended to the next-to-leading order in the…

High Energy Physics - Phenomenology · Physics 2022-04-04 Tomáš Husek

The Vector Pion form factor below 1 GeV is analyzed using experimental data on its modulus, the P-wave pion pion phase shifts and dispersion relation. It is found that causality is satisfied. Using dispersion relation, terms proportional to…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tran N. Truong

We evaluate the pion mass in finite volume to two loops within Chiral Perturbation Theory. The results are compared with a recently proposed extension of the asymptotic formula of Luscher. We find that contributions, which were neglected in…

High Energy Physics - Lattice · Physics 2007-05-23 Christoph Haefeli

We calculate the $\phi$-meson propagator at finite temperature at the one--loop order. The real and imaginary parts are studied separately in full kinematic ranges. From this activity we investigate how temperature affects such things as…

Nuclear Theory · Physics 2009-10-28 Kevin L. Haglin , Charles Gale

We give a review of modern theoretical understanding of the physics of QCD at finite temperature. Three temperature regions are studied in details: the low temperature region where the system presents a rarefied pion gas and its properties…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. V. Smilga

We investigate the properties of the pion quasiparticle in the low-temperature phase of two-flavor QCD on the lattice with support from chiral effective theory. We find that the pion quasiparticle mass is significantly reduced compared to…

High Energy Physics - Lattice · Physics 2015-09-22 Bastian B. Brandt , Anthony Francis , Harvey B. Meyer , Daniel Robaina

We present a parameter--free calculation of the dispersive and absorptive contributions to the pion--deuteron scattering length based on chiral perturbation theory. We show that once all diagrams contributing to leading order to this…

Nuclear Theory · Physics 2008-11-26 V. Lensky , V. Baru , J. Haidenbauer , C. Hanhart , A. Kudryavtsev , U. -G. Meißner

Properties of the pion are studied at finite temperature with the help of the PCAC and the QCD sum rule. The pionic mode is treated consistently with the thermal pions which consist of the ground state at finite temperature. The temperature…

High Energy Physics - Phenomenology · Physics 2016-09-01 Nobuaki Kodama , Makoto Oka

The density corrections, in terms of the isospin chemical potential $\mu_I$, to the mass of the pions are investigated in the framework of the SU(2) low energy effective chiral invariant lagrangian. As a function of temperature and $\mu_I…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. Loewe , C. Villavicencio

The thermal corrections to the propagator of a loosely bound charm-meson molecule in a pion gas are calculated to next-to-leading order in the heavy-meson expansion using a zero-range effective field theory. Ultraviolet divergences in the…

High Energy Physics - Phenomenology · Physics 2023-09-13 Eric Braaten , Li-Ping He , Kevin Ingles , Jun Jiang

We compute the finite temperature pole mass shifts of the octet and decuplet baryons using heavy baryon chiral perturbation theory and the 1/N_c expansion, where N_c is the number of QCD colors. We consider temperatures of the order of the…

High Energy Physics - Phenomenology · Physics 2014-11-17 Paulo F. Bedaque