On baryon resonances and chiral symmetry

We study J^P=(3/2)^- baryon resonances as generated by chiral coupled-channel dynamics. Parameter free results are obtained in terms of the Weinberg-Tomozawa term predicting the leading s-wave interaction strength of Goldstone bosons with baryon-decuplet states. In the 'heavy' SU(3) limit with m_\pi = m_K \sim 500 MeV the resonances turn into bound states forming a decuplet and octet representation of the SU(3) group. Using physical masses the mass splitting are remarkably close to the empirical pattern.Comment: revised version: includes two additional references, gives improved discussions and eliminted some misprint

Baryon resonances from chiral coupled-channel dynamics

We discuss the formation of s- and d-wave baryon resonances as predicted by the chiral SU(3) symmetry of QCD. Based on the leading order term of the chiral Lagrangian a rich spectrum of molecules is generated, owing to final-state interactions. The spectrum of s- and d-wave baryon states with zero and non-zero charm is remarkably consistent with the empirical pattern. In particular, the recently announced Sigma_c(2800) of the BELLE collaboration is reproduced with realistic mass and width parameters. Similarly, the d-wave states Lambda_c(2625) and Xi_c(2815) are explained naturally to be chiral excitations of J^P=3/2^+ states. In the open-charm sector exotic multiplet structures are predicted. These findings support a radical conjecture: meson and baryon resonances that do not belong to the large-N_c ground state of QCD should be viewed as hadronic molecular state

On heavy-light meson resonances and chiral symmetry

We study heavy-light meson resonances with quantum numbers J^P=0^+ and J^P=1^+ in terms of the non-linear chiral SU(3) Lagrangian. At leading order a parameter-free prediction is obtained for the scattering of Goldstone bosons off heavy-light pseudo-scalar and vector mesons once we insist on approximate crossing symmetry of the unitarized scattering amplitude. The recently announced narrow open charm states observed by the BABAR and CLEO collaborations are reproduced. We suggest the existence of states that form an anti-triplet and a sextet representation of the SU(3) group. In particular, so far unobserved narrow isospin-singlet states with negative strangeness (I,S)=(0,-1) are predicted at 2361 MeV J^P=0^+ and 2501 MeV (J^P=1^+). Similarly, open bottom states are found at 5719 MeV (J^P=0^+) and 5622 MeV (J^P=1^+). Additional narrow states of mass 5580 MeV (J^P=0^+) and 5650 MeV (J^P=1^+) with widths of about 50 MeV are obtained in the (I,S)=(1,1) sector. For the anti-triplet states our results differ most significantly from predictions that are based on a linear realization of the chiral SU(3) symmetry in the open bottom sector. Strongly bound 0^+-and 1^+-states with (I,S)=(0,1) at 5507 MeV and 5553 MeV are predicted.Comment: revised manuscript: improved discussion and minor correction

On meson resonances and chiral symmetry

We study meson resonances with quantum numbers J^P=1^+ in terms of the chiral SU(3) Lagrangian. At leading order a parameter-free prediction is obtained for the scattering of Goldstone bosons off vector mesons with J^P=1^- once we insist on approximate crossing symmetry of the unitarized scattering amplitude. A resonance spectrum arises that is remarkably close to the empirical pattern. In particular, we find that the strangeness-zero resonances h_1(1380), f_(1285) and b_1(1235) are formed due to strong K \bar K_\mu and \bar K K_\mu channels. This leads to large coupling constants of those resonances to the latter states.Comment: 29 pages, 6 figures, more detailed discussions are give

Electromagnetic transitions in an effective chiral Lagrangian with the eta-prime and light vector mesons

We consider the chiral Lagrangian with a nonet of Goldstone bosons and a nonet of light vector mesons. The mixing between the pseudoscalar mesons eta and eta-prime is taken into account. A novel counting scheme is suggested that is based on hadrogenesis, which conjectures a mass gap in the meson spectrum of QCD in the limit of a large number of colors. Such a mass gap would justify to consider the vector mesons and the eta-prime meson as light degrees of freedom. The complete leading order Lagrangian is constructed and discussed. As a first application it is tested against electromagnetic transitions of light vector mesons to pseudoscalar mesons. Our parameters are determined by the experimental data on photon decays of the omega, phi and eta-prime meson. In terms of such parameters we predict the corresponding decays into virtual photons with either dielectrons or dimuons in the final state.Comment: 17 pages, extended discussion on mixin

The socio-cultural perception of death in Turkish society recorded in lament epics (1955-1975)

This study explores the socio-cultural perception of death among Turkish people. For this reason, 210 published lament epics written by Turkish folk singers across all of Turkey concerning deaths between 1955 and 1975 were selected for analysis. These epics were published on single pages and were sold. The statistical analysis based on detailed content analysis was done at the univariate, bivariate, and multivariate levels. The results of the study provide a full picture of perception of cases of death in Turkish society. These results show Turkish society is especially sensitive to cases of death at young age and to the murdered. Further, a clear perception of the working of fate is encountered in deaths resulting from disaster and accidents; but the desire for vengeance is recorded in those laments concerning martyrs and the murdered. The statistical data show that most commonly cited reasons for death after road accidents, were a consequence of relationships with the opposite sex and from a sense of honor. © 2014, Baywood Publishing Co., Inc

Negative Kaons in Dense Baryonic Matter

Kaon polarization operator in dense baryonic matter of arbitrary isotopic composition is calculated including s- and p-wave kaon-baryon interactions. The regular part of the polarization operator is extracted from the realistic kaon-nucleon interaction based on the chiral and 1/N_c expansion. Contributions of the Lambda(1116), Sigma(1195), Sigma*(1385) resonances are taken explicitly into account in the pole and regular terms with inclusion of mean-field potentials. The baryon-baryon correlations are incorporated and fluctuation contributions are estimated. Results are applied for K- in neutron star matter. Within our model a second-order phase transition to the s-wave K- condensate state occurs at rho_c \gsim 4 \rho_0 once the baryon-baryon correlations are included. We show that the second-order phase transition to the p-wave $K^-$ condensate state may occur at densities $\rho_c \sim 3\div 5 \rho_0$ in dependence on the parameter choice. We demonstrate that a first-order phase transition to a proton-enriched (approximately isospin-symmetric) nucleon matter with a p-wave K- condensate can occur at smaller densities, \rho\lsim 2 \rho_0. The transition is accompanied by the suppression of hyperon concentrations.Comment: 41 pages, 24 figures, revtex4 styl

Level crossing of particle-hole and mesonic modes in eta mesic nuclei

We study eta meson properties in the infinite nuclear matter and in atomic nuclei with an emphasis on effects of the eta coupling to N*(1535)--nucleon-hole modes. The N*(1535) resonance, which dominates the low-energy eta-nucleon scattering, can be seen as a chiral partner of the nucleon. The change of the chiral mass gap between the N* and the nucleon in a nuclear medium has an impact on the properties of the eta-nucleus system. If the N*-nucleon mass gap decreases with a density increase (chiral symmetry restoration) the calculations show the existence of the resonance state at the energy about 60 MeV and two bound eta-nucleus states with the binding energies about -80 MeV. These states can have strong effect on predicted cross sections of the ^12C (gamma,p) ^11B reaction with eta-meson production.Comment: 22 pages, 12 figure

Light meson mass dependence of the positive parity heavy-strange mesons

We calculate the masses of the resonances D_{s0}^*(2317) and D_{s1}(2460) as well as their bottom partners as bound states of a kaon and a D^*- and B^*-meson, respectively, in unitarized chiral perturbation theory at next-to-leading order. After fixing the parameters in the D_{s0}^*(2317) channel, the calculated mass for the D_{s1}(2460) is found in excellent agreement with experiment. The masses for the analogous states with a bottom quark are predicted to be M_{B^*_{s0}}=(5696\pm 40) MeV and M_{B_{s1}}=(5742\pm 40) MeV in reasonable agreement with previous analyses. In particular, we predict M_{B_{s1}}-M_{B_{s0}^*}=46\pm 1 MeV. We also explore the dependence of the states on the pion and kaon masses. We argue that the kaon mass dependence of a kaonic bound state should be almost linear with slope about unity. Such a dependence is specific to the assumed molecular nature of the states. We suggest to extract the kaon mass dependence of these states from lattice QCD calculations.Comment: 10 page

Solar-Type Post-T Tauri Stars in the Nearest OB Subgroups

I discuss results from the recent spectroscopic survey for solar-type pre-MS stars in the Lower Centaurus-Crux (LCC) and Upper Centaurus-Lupus (UCL) OB subgroups by Mamajek, Meyer, & Liebert (2002, AJ, 124, 1670). LCC and UCL are subgroups of the Sco-Cen OB association, and the two nearest OB subgroups to the Sun. In the entire survey of 110 pre-main sequence stars, there exists only one Classical T Tauri star (PDS 66), implying that only ~1% of ~1 Msun stars are still accreting at age 13$\pm$7 (1$\sigma$) Myr. Accounting for observational errors, the HRD placement of the pre-MS stars is consistent with the bulk of star-formation taking place within 5-10 Myr. In this contribution, I estimate conservative upper limits to the intrinsic velocity dispersions of the post-T Tauri stars in the LCC and UCL subgroups (<1.6 km/s and <2.2 km/s, respectively; 95% CL) using Monte-Carlo simulations of Tycho-2 proper motions for candidate subgroup members. I also demonstrate that a new OB subgroup recently proposed to exist in Chamaeleon probably does not.Comment: 8 pages, 2 figures, to appear in proceedings for "Open Issues in Local Star Formation and Early Stellar Evolution", eds. J. Gregorio-Hetem & J. Lepine. Minor edits (5/30/03