Bound states of $��^+$ in nuclei

We study the binding energy and the width of the $��^+$ in nuclei, associated to the $K N$ and $ K ��N$ components. The first one leads to negligible contributions while the second one leads to a sizeable attraction, enough to bind the $��^+$ in nuclei. Pauli blocking and binding effects on the $K N$ decay reduce considerably the $��^+$ decay width in nuclei and medium effects associated to the $ K ��N$ component also lead to a very small width, as a consequence of which one finds separation between the bound levels considerably larger than the width of the states.

Strange and charm mesons at FAIR

Presented at the XXXI Mazurian Lakes Conference on Physics, Piaski, Poland, August 30–September 6, 2009.

φ meson mass and decay width in nuclear matter

The $\phi$ meson spectrum, which in vacuum is dominated by its coupling to the $\bar{K} K$ system, is modified in nuclear matter. Following a model based on chiral SU(3) dynamics we calculate the $\phi$ meson selfenergy in nuclear matter considering the $K$ and $\bar{K}$ in-medium properties. For the latter we use the results of previous calculations which account for $S-$ and $P-$wave kaon-nucleon interactions based on the lowest order meson-baryon chiral effective Lagrangian, and this leads to a dressing of the kaon propagators in the medium. In addition, a set of vertex corrections is evaluated to fulfill gauge invariance, which involves contact couplings of the $\phi$ meson to $S-$wave …

Mass dependence of inclusive nuclear $\phi$ photoproduction

Based on a prior determination of the $\phi$ selfenergy in a nuclear medium we perform a theoretical study of inclusive $\phi$ photoproduction in nuclei, looking at the $A$ dependence of the cross sections for different $\phi$ momenta. We find sizeable reductions in the nuclear cross sections with respect to the elementary one, using a $\phi$ selfenergy which implies a width about six times the free one at normal nuclear density. The calculations are done to match the set up for an ongoing experiment at {\it SPring8/Osaka} which should provide valuable information on the renormalization of the $\phi$ properties in nuclei.

Evaluation of the pi pi-scattering amplitude in the sigma-channel at finite density

The $\pi\pi$ scattering amplitude in the $\sigma$-channel is studied at finite baryonic density in the framework of a chiral unitary approach which successfully reproduces the meson meson phase shifts and generates the $f_0$ and $\sigma$ resonances in vacuum. We address here a new variety of mechanisms recently suggested to modify the $\pi\pi$ interaction in the medium, as well as the role of the $s-$wave selfenergy, in addition to the $p-$wave, in the dressing of the pion propagators.

Chiral unitary theory: Application to nuclear problems

In this talk we briefly describe some basic elements of chiral perturbation theory, $\chi PT$, and how the implementation of unitarity and other novel elements lead to a better expansion of the $T$ matrix for meson meson and meson baryon interactions. Applications are then done to the $ \pi \pi $ interaction in nuclear matter in the scalar and vector channels, antikaons in nuclei and $K^-$ atoms, and how the $\phi$ meson properties are changed in a nuclear medium.

Formation of phi Mesic Nuclei

We study the structure and formation of the $\phi$ mesic nuclei to investigate the in-medium modification of the $\phi$-meson spectral function at finite density. We consider (${\bar p},\phi$), ($\gamma,p$) and ($\pi^-,n$) reactions to produce a $\phi$-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the ${\bar K}$ selfenergy in medium to the $\phi$-nucleus interaction. We find that it may be possible to see a peak structure in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attr…

Chiral approach to the rho meson in nuclear matter

In this work, the properties of the $\rho$ meson at rest in cold symmetric nuclear matter are studied. We make use of a chiral unitary approach to pion-pion scattering in the vector-isovector channel, calculated from the lowest order Chiral Perturbation Theory ($\chi PT$) lagrangian including explicit resonance fields. Low energy chiral constraints are considered by matching our expressions to those of one loop $\chi PT$. To account for the medium corrections, the $\rho$ couples to $\pi\pi$ pairs which are properly renormalized in the nuclear medium, accounting for both $p-h$ and $\Delta -h$ excitations. The terms where the $\rho$ couples directly to the hadrons in the $p-h$ or $\Delta -h$ …

Chiral unitary approach to the rho meson in the nuclear medium

Kaon-antikaon nuclear optical potentials and the kappa meson in the nuclear medium

We study the properties of the kappa meson in the nuclear medium, starting from a chiral unitary model of S-wave, I=1/2 K-pi scattering, which describes the elastic K-pi phase shifts and generates a pole in the amplitude. Medium effects are considered by including pion and kaon selfenergies. We explore the changes in the kappa pole position and in the K-pi scattering amplitude at finite density, with two different models for the kaon selfenergy.

Chiral dynamics of baryon resonances and hadrons in a nuclear medium

In these lectures I make an introduction to chiral unitary theory applied to the meson baryon interaction and show how several well known resonances are dynamically generated, and others are predicted. Two very recent experiments are analyzed, one of them showing the existence of two $\Lambda(1405)$ states and the other one providing support for the $\Lambda(1520)$ resonance as a quasibound state of $\Sigma(1385) \pi$. The use of chiral Lagrangians to account for the hadronic interaction at the elementary level introduces a new approach to deal with the modification of meson and baryon properties in a nuclear medium. Examples of it for $\bar{K}$, $\eta$ and $\phi$ modification in the nuclea…

The rho meson in a nuclear medium

In this work, propagation properties of the rho meson in symmetric nuclear matter are studied. We make use of a coupled channel unitary approach to meson-meson scattering, calculated from the lowest order Chiral Perturbation Theory lagrangian including explicit resonance fields. Low energy chiral constraints are considered by matching our expressions to those of one loop Ch.P.T. To account for the medium corrections, the rho couples to pion-pion and kaon-antikaon pairs which are properly renormalized in the nuclear medium.

ϕ meson transparency in nuclei from ϕN resonant interactions

We investigate the $\ensuremath{\phi}$ meson nuclear transparency using some recent theoretical developments on the $\ensuremath{\phi}$ in medium self-energy. The inclusion of direct resonant $\ensuremath{\phi}N$ scattering and the kaon decay mechanisms leads to a $\ensuremath{\phi}$ width much larger than in most previous theoretical approaches. The model has been confronted with photoproduction data from CLAS and LEPS and the recent proton induced $\ensuremath{\phi}$ production from COSY finding an overall good agreement. The results support the need of a quite large direct $\ensuremath{\phi}N$-scattering contribution to the self-energy.