相关论文: S-wave $\pi$-Nucleus Repulsion and Dirac Phenomeno…

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…

Several mechanisms of density dependence of the s-wave repulsion in pionic atoms, beyond the conventional model, are tested by parameter fits to a large (106 points) set of data from $^{16}$O to $^{238}$U, including `deeply bound' states in…

Differential cross sections for elastic scattering of 21.5 MeV positive and negative pions by Si, Ca, Ni and Zr have been measured as part of a study of the pion-nucleus potential across threshold. The `anomalous' repulsion in the s-wave…

The Laser Interferometer Gravitational-Wave Observatory (LIGO) detection of gravitational waves that take away 5 per cent of the total mass of two merging black holes points out on the importance of considering varying gravitational mass of…

The s-wave correlated $\pi$-$\pi$ strength distribution in cold nuclear matter is investigated. The in-medium single pions are renormalized by means of the usual p-wave couplings to nucleons and $\Delta$'s. Two groups of models for the…

Strong interaction level shifts and widths in $\Sigma^-$ atoms are analyzed by using a $\Sigma$ nucleus optical potential constructed within the relativistic mean field approach. The analysis leads to potentials with a repulsive real part…

The nuclear force has been understood to have a repulsive core at short distances, similar to a molecular force, since Jastrow proposed it in 1951. The existence of the repulsion was experimentally confirmed from the proton-proton…

We work in a chiral invariant quark model, with a condensed vacuum, characterized by only one parameter. Bound state equations for the nucleon and Delta are solved in order to obtain an updated value of their radii and masses.…

Fits to a large data set of pionic atoms show that the `missing' s-wave repulsion is accounted for when a density dependence suggested recently by Weise is included in the isovector term of the s-wave pion optical potential. The importance…

We present in this article an optical potential for the $\pi$-nucleus interaction that can be used in various studies involving $\pi$-nucleus channels. Based on earlier treatments of the low energy $\pi$-nucleus optical potential, we have…

The strong coupling of rho meson to the nucleon produces $s$ and $p$ wave rho meson nucleon $(\rho N)$ resonances. In a nucleus, the $\rho N$ resonance-hole polarization generates the optical potential or self-energy for the rho meson. The…

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…

The three nucleon interaction that arises from pion and the effective scalar and vector meson exchange components of the nucleon-nucleon interaction is constructed and shown to be repulsive. Using several wavefunction models we show that…

Repulsive singularities (repulsons) in extended supergravity theories are investigated. These repulsive singularities are related to attractive singularities (black holes) in moduli space of extended supergravity vacua. In order to study…

We present and discuss a systematic calculation, based on two-loop chiral perturbation theory, of the pion-nuclear s-wave optical potential. A proper treatment of the explicit energy dependence of the off-shell pion self-energy together…

Low energy theorems are derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading order in an expansion in which both $m_\pi$ and $1/a$ (where $a$ is the scattering length) are…

The Pauli exclusion principle plays an important role in many-body fermion systems preventing them from collapsing by repulsion. For example, the Pauli principle causes a repulsive potential at short distances between two $\alpha$…

We study phenomenologically inclusive spectra of the $^6$Li($\pi^-$, $K^+$) reaction at 1.2 GeV/$c$ within a distorted-wave impulse approximation with the optimal Fermi-averaging $\pi^- p \to K^+ \Sigma^-$ $t$ matrix. We attempt to clarify…

We evaluate the contribution of second order terms to the pion-nucleus s-wave optical potential of pionic atoms generated by short range nuclear correlation. The corrections are sizeable because they involve the isoscalar s-wave $\pi N$…

The results of the recent experiments on the reaction $\pi^-p\to\pi^0\pi^0n$ performed at KEK, BNL, IHEP, and CERN are analyzed in detail. For the I=0 $\pi\pi$ S wave phase shift $\delta^0_0$ and inelasticity $\eta^0_0$ a new set of data is…