Electric dipole moment of light nuclei in chiral effective field theory

CP-violating interactions at quark level generate CP-violating nuclear interactions and currents, which could be revealed by looking at the presence of a permanent nuclear electric dipole moment. Within the framework of chiral effective field theory, we discuss the derivation of the CP-violating nuclear potential up to next-to-next-to leading order (N2LO) and the preliminary results for the charge operator up to next-to leading order (NLO). Moreover, we introduce some renormalization argument which indicates that we need to promote the short-distance operator to the leading order (LO) in order to reabsorb the divergences generated by the one pion exchange. Finally, we present some selected numerical results for the electric dipole moments of 2H, 3He and 3H discussing the systematic errors introduced by the truncation of the chiral expansion.

The KN Interaction in Higher Partial Waves

We present a chiral K¯N interaction model that has been developed and optimized in order to account for the experimental data of inelastic K¯N reaction channels that open at higher energies. In particular, we study the effect of the higher partial waves, which originate directly from the chiral Lagrangian, as they could supersede the role of high-spin resonances employed in earlier phenomenological models to describe meson-baryon cross sections in the 2 GeV region. We present a detailed derivation of the partial wave amplitudes that emerge from the chiral SU(3) meson-baryon Lagrangian up to the d-waves and next-to-leading order in the chiral expansion. We implement a nonperturbative unitarization in coupled channels and optimize the model parameters to a large pool of experimental data in the relevant energy range where these new contributions are expected to be important. The obtained results are encouraging. They indicate the ability of the chiral higher partial waves to extend the description of the scattering data to higher energies and to account for structures in the reaction cross-sections that cannot be accommodated by theoretical models limited to the s-waves.

Modern Chiral Forces Applied to the Neutron-Deuteron Breakup Reaction

We report on applications of the recent chiral potentials from the Bochum-Bonn group to the description of the neutron induced deuteron breakup observables. Specifically, we discuss the convergence of predictions with respect to the chiral order and the dependence of our results on the value of the regularization parameter. To that end we use the chiral forces with semi-local coordinate or momentum space regularization up to the N$$^4$$ 4 LO$$^+$$ + order of chiral expansion. We find a satisfactory picture revealing high quality of the chiral forces used.

Scattering of two and three physical pions at maximal isospin from lattice QCD

We present the first direct $$N_f=2$$ N f = 2 lattice QCD computation of two- and three-$$\pi ^+$$ π + scattering quantities that includes an ensemble at the physical point. We study the quark mass dependence of the two-pion phase shift, and the three-particle interaction parameters. We also compare to phenomenology and chiral perturbation theory (ChPT). In the two-particle sector, we observe good agreement to the phenomenological fits in s- and d-wave, and obtain $$M_\pi a_0 = -0.0481(86)$$ M π a 0 = - 0.0481 ( 86 ) at the physical point from a direct computation. In the three-particle sector, we observe reasonable agreement at threshold to the leading order chiral expansion, i.e. a mildly attractive three-particle contact term. In contrast, we observe that the energy-dependent part of the three-particle quasilocal scattering quantity is not well described by leading order ChPT.

Strong CP violation in spin-1/2 singly charmed baryons

We report on the calculation of the CP-violating form factor F3 and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD θ-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

Properties of heavy mesons at finite temperature

We study the properties of heavy mesons using a unitarized approach in a hot pionic medium, based on an effective hadronic theory. The interaction between the heavy mesons and pseudoscalar Goldstone bosons is described by a chiral Lagrangian at next-to-leading order in the chiral expansion and leading order in the heavy-quark mass expansion so as to satisfy heavy-quark spin symmetry. The meson-meson scattering problem in coupled channels with finite-temperature corrections is solved in a self-consistent manner. Our results show that the masses of the ground-state charmed mesons D(0^-)D(0−) and D_s(1^-)Ds(1−) decrease in a pionic environment at T\neq 0T≠0 and they acquire a substantial width. As a consequence, the behaviour of excited mesonic states (D_{s0}^*(2317)^\pmDs0*(2317)± and D_0^*(2300)^{0,\pm}D0*(2300)0,±), generated dynamically in our heavy-light molecular model, is also modified at T\neq 0T≠0. The aim is to test our results against Lattice QCD calculations in the future.

Investigations of the few-nucleon systems within the LENPIC project

Results presented in this contribution are obtained within the Low Energy Nuclear Physics International Collaboration (LENPIC). LENPIC aims to develop chiral nucleon-nucleon and many-nucleon interactions complete through at least the fourth order in the chiral expansion. These interactions will be used together with consistently derived current operators to solve the structure and reactions of light and medium-mass nuclei including electroweak processes. In this contribution the current status of the chiral nuclear forces and current operators will be briefly discussed. A special role played by the calculations of nucleon-deuteron scattering will be explained.

Optical Potentials: Microscopic vs. Phenomenological Approaches

In this work we study the performances of our microscopic optical potential [1, 2], derived from nucleon-nucleon chiral potentials at fifth order (N4LO), in comparison with those of a successful non-relativistic phenomenological optical potential in the description of elastic proton scattering data on tin and lead isotopes at energies around and above 200 MeV. Our results indicate that microscopic optical potentials derived from nucleon-nucleon chiral potentials at N4LO can provide reliable predictions for observables of stable and exotic nuclei, even at energies where the robustness of the chiral expansion starts to be questionable.