0000000001234023
AUTHOR
Hideko Nagahiro
Hidden gauge formalism for the radiative decays of axial-vector mesons
24 pages, 6 tables, 11 figures.--ISI article identifier:000262979700040 .-- ArXiv pre-print avaible at:http://arxiv.org/abs/0809.0943
Possible omega bound states in nuclei produced with the (gamma, p) reaction
We perform calculations for ω production in nuclei by means of the (γ,p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible ω optical potentials, we find that clear peaks are observable when a good resolution in the ω energy is available. We also study the inclusive production of π(0)γ in nuclei around the ω energy and find a double hump structure for the energy spectra, with a peak around a π(0)γ energy of m(ω) -100 MeV, which could easily be misidentified by a signal of an ω bound state in nuclei, while it is actually due to a different scaling of the uncorrelated π(0)γ production and ω prod…
Decay of vector-vector resonances into $\gamma$ and a pseudoscalar meson
We study the decay of dynamically generated resonances from the interaction of two vectors into a $\ensuremath{\gamma}$ and a pseudoscalar meson. The dynamics requires anomalous terms involving vertices with two vectors and a pseudoscalar, which renders it special. We compare our result with data on ${K}_{2}^{*+}(1430)\ensuremath{\rightarrow}{K}^{+}\ensuremath{\gamma}$ and ${K}_{2}^{*0}(1430)\ensuremath{\rightarrow}{K}^{0}\ensuremath{\gamma}$ and find a good agreement with the data for the ${K}_{2}^{*+}(1430)$ case and a width considerably smaller than the upper bound measured for the ${K}_{2}^{*0}(1430)$ meson. We also investigate the decay into ${\ensuremath{\pi}}^{+}\ensuremath{\gamma}$ …
Role of meson loops in the f(0)(1370), f(0)(1500), and f(0)(1710) decays into V gamma
We investigate the relevance of the meson loops in the f0(1710) scalar meson decay into one photon and one vector meson, (ρ, ω and ϕ). In particular we estimate the size of the loops coming from the decay of the f0(1710) into two pseudoscalar mesons, containing three pseudoscalar mesons in the loop or two pseudoscalar and one vector meson. The results, despite having large uncertainties, manifest that the contribution of the meson loops to these radiative decays is quite relevant and should be taken into account by the theoretical calculations which use this observables as a test of the possible glueball nature of this resonance.
Production of Θ+ hypernuclei with the (K+,π+) reaction
Abstract We present results on the production of bound states of Θ + in nuclei using the ( K + , π + ) reaction. By taking into account the states obtained within a wide range of strength of the Θ + nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range.
eta '-Nucleus optical potential and possible eta ' bound states
Starting from a recent model of the eta'N interaction, we evaluate the eta'-nucleus optical potential, including the contribution of lowest order in density, t rho/2m(eta'), together with the second-order terms accounting for eta' absorption by two nucleons. We also calculate the formation cross section of the eta' bound states from (pi(+), p) reactions on nuclei. The eta'-nucleus potential suffers from uncertainties tied to the poorly known eta'N interaction, which can be partially constrained by the experimental modulus of the eta'N scattering length and/or the recently measured transparency ratios in eta' nuclear photoproduction. Assuming an attractive interaction and taking the claimed …
η′-Nucleus optical potential and possible η′ bound states
Abstract Starting from a recent model of the η ′ N interaction, we evaluate the η ′ -nucleus optical potential, including the contribution of lowest order in density, t ρ / 2 m η ′ , together with the second-order terms accounting for η ′ absorption by two nucleons. We also calculate the formation cross section of the η ′ bound states from ( π + , p ) reactions on nuclei. The η ′ -nucleus potential suffers from uncertainties tied to the poorly known η ′ N interaction, which can be partially constrained by the experimental modulus of the η ′ N scattering length and/or the recently measured transparency ratios in η ′ nuclear photoproduction. Assuming an attractive interaction and taking the c…
Radiative decay intoγPof the low lying axial-vector mesons
We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson interaction. We take into account tree level and loop diagrams coming from the axial-vector decay into a vector and a pseudoscalar meson. We find a large span for the values of the radiative widths of the different axial-vector mesons. In particular, we evaluate the radiative decay into K{gamma} of the two K{sub 1}(1270) states, recently claimed theoretically, and discuss the experimental values quoted so far on the assumption of only one state.
PRODUCTION OF Θ+ HYPERNUCLEI WITH THE (K+, π+) REACTION
Abstract We present results on the production of bound states of Θ + in nuclei using the ( K + , π + ) reaction. By taking into account the states obtained within a wide range of strength of the Θ + nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range.
Possible ω bound states in nuclei produced with the (γ,p) reaction
We perform calculations for ω production in nuclei by means of the ( γ, p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible ω optical potentials, we find that clear peaks are observable when a good resolution in the ω energy is available. We also study the inclusive production of π 0 γ in nuclei around the ω energy and find a double hump structure for the energy spectra, with a peak around a π 0 γ energy of mω − 100 MeV, which could easily be misidentified by a signal of an ω bound state in nuclei, while it is actually due to a different scaling of the uncorrelated π 0 γ production and ω pro…
Precision Spectroscopy of Deeply Bound Pionic Atoms and Partial Restoration of Chiral Symmetry in Medium
We study theoretically the formation spectra of deeply bound pionic atoms expected to be observed by experiments with high energy resolution at RIBF/RIKEN, and we discuss in detail the possibilities to extract new information on the pion properties at finite density from the observed spectra, which may provide information on partial restoration of chiral symmetry in medium. We find that the non-yrast pionic states such as 2s are expected to be seen in the (d,3He) spectra, which will be helpful to reduce uncertainties of the theoretical calculations in the neutron wave functions in nucleus. The observation of the 2s state with the ground 1s state is also helpful to reduce the experimental un…
Formation of Heavy Meson Bound States by Two Nucleon Pick-up Reactions
We develop a model to evaluate the formation rate of the heavy mesic nuclei in the two nucleon pick-up reactions, and apply it to the $^6$Li target cases for the formation of heavy meson-$\alpha$ bound states, as examples. The existence of the quasi-deuteron in the target nucleus is assumed in this model. It is found that the mesic nuclei formation in the recoilless kinematics is possible even for heavier mesons than nucleon in the two nucleon pick-up reactions. We find the formation rate of the meson-$\alpha$ bound states can be around half of the elementary cross sections at the recoilless kinematics with small distortions.
Meson and baryon resonances
6 pages, 1 table.-- PACS nrs.: 13.75.Lb, 14.40.Cs, 12.40.Vv, 12.40.Yx.-- Talk at the 2008 International Conference on Particles And Nuclei (PANIC08, Nov 9-14, 2008, Eilat, Israel).
Radiative decay into $\gamma P$ of the low lying axial-vector mesons
We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson ($VP$) interaction. We take into account tree level and loop diagrams coming from the axial-vector decay into a vector and a pseudoscalar meson. We find a large span for the values of the radiative widths of the different axial-vector mesons. In particular, we evaluate the radiative decay into $K \gamma$ of the two $K_1(1270)$ states, recently claimed theoretically, and discuss the experimental values quoted so far on the assumption of only one state.
Meson loops in the $f_0(980)$ and $a_0(980)$ radiative decays into $\rho$, $\omega$
We calculate the radiative decay widths of the $a_0(980)$ and $f_0(980)$ scalar mesons into $\rho\gamma$ and $\omega\gamma$ considering the dynamically generated nature of these scalar resonances within the realm of the Chiral Unitary Approach. The main ingredient in the evaluation of the radiative width of the scalar mesons are the loops coming from the decay into their constituent pseudoscalar-pseudoscalar components and the subsequent radiation of the photon. The dominant diagrams with only pseudoscalar mesons in the loops are found to be convergent while the divergence of those with a vector meson in the loop are written in terms of the two meson loop function easily regularizable. We p…
gamma gamma decay of the f(0)(1370) and f(2)(1270) resonances in the hidden gauge formalism
Using recent results obtained within the hidden gauge formalism for vector mesons, in which the f0(1370) and f2(1270) resonances are dynamically generated resonances from the ρρ interaction, we evaluate the radiative decay of these resonances into γγ. We obtain results for the width in good agreement with the experimental data for the f2(1270) state and a width about a factor five smaller for the f0(1370) resonance, which would agree with preliminary results from the Belle collaboration, hinting at an order of magnitude smaller width for this resonance than for the f2(1270).