Low-mass scalar production in γγ\gamma \gamma scattering

We estimate the I=0 scalar meson $\sigma/f_0(600)$ $\gamma\gamma$ widths, from $\pi\pi$ and $\gamma\gamma$ scattering data below 700 MeV using an improved analytic K-matrix model.Comment: 3 pages, 2 figures, Talk given at QCD 08 (Montpellier 7-12th july 2008

The sigma and f_0(980) from K_e4+pi-pi, gamma-gamma scatterings, J/psi, phi to gamma sigma_B and D_s to l nu sigma_B

We extract the pole positions, hadronic and gamma-gamma widths of sigma and f_0(980, from pi-pi and gamma-gamma scattering data using an improved analytic K-matrix model. Our results favour a large gluon component for the sigma and a \bar ss or/and gluon component for the f_0(980) but neither a large four-quark nor a molecule component. Gluonium sigma_B production from J/psi, phi radiative and D_s semi-leptonic decays are also discussed.Comment: 4 pages, 5 figures, 6 tables, talk given by X.-G. Wang at QCD 10 (25th anniversary) 28th june-2nd july 2010 (Montpellier - FR

sigma and f_0(980) substructures from gamma-gamma to pi-pi, J/psi, phi radiative and D_s semi-leptonic decays

Using an improved "analytic K-matrix model", we reconsider the extraction of the sigma/f_0(600) and f_0(980) gamma-gamma widths from gamma-gamma to pi-pi scatterings data of Crystal Ball and Belle. Our main results are summarized in Tables 3 and 4. The averaged sigma "direct width" to gamma-gamma is 0.16(3) keV which confirms a previous result of [1] and which does neither favour a large four-quark (diquark-antidiquark) nor a molecule nor a pure \bar qq component. The "direct width" of the f_0(980) of 0.28(2) keV is much larger than the four-quark expectation but can be compatible with a \bar ss or gluonium component. We also found that the rescattering part of the amplitude is relatively large indicating an important contribution of the meson loops in the determination of the gamma-gamma total widths. This is mainly due to the large couplings of the sigma and f_0(980) to pi-pi and/or \bar KK, which can also be due to a light scalar gluonium with large OZI violating couplings but not necessary to a four-quark or molecule state. Our average results for the total (direct+rescattering) gamma-gamma widths: Gamma_sigma^{tot}= 3.08(82) keV, Gamma_{f_0}^{tot}= 0.16(1) keV} are comparable with the ones from dispersion relations and PDG values. Using the parameters from QCD spectral sum rules, we complete our analysis by showing that the production rates of unmixed scalar gluonia sigma_B(1) and G (1.5-1.6) agree with the data from J/\psi, phi radiative and D_s semi-leptonic decays.Comment: 11 pages, 6 figures (1 more figure added in Fig 6), 4 tables : version appeared on-line in doi:10.1016/j.physletb.2010.12.00

Period-Luminosity-Colour distribution and classification of Galactic oxygen-rich LPVs

The absolute K magnitudes and kinematic parameters of about 350 oxygen-rich Long-Period Variable stars are calibrated, by means of an up-to-date maximum-likelihood method, using Hipparcos parallaxes and proper motions together with radial velocities and, as additional data, periods and V-K colour indices. Four groups, differing by their kinematics and mean magnitudes, are found. For each of them, we also obtain the distributions of magnitude, period and de-reddened colour of the base population, as well as de-biased period-luminosity-colour relations and their two-dimensional projections. The SRa semiregulars do not seem to constitute a separate class of LPVs. The SRb appear to belong to two populations of different ages. In a PL diagram, they constitute two evolutionary sequences towards the Mira stage. The Miras of the disk appear to pulsate on a lower-order mode. The slopes of their de-biased PL and PC relations are found to be very different from the ones of the Oxygen Miras of the LMC. This suggests that a significant number of so-called Miras of the LMC are misclassified. This also suggests that the Miras of the LMC do not constitute a homogeneous group, but include a significant proportion of metal-deficient stars, suggesting a relatively smooth star formation history. As a consequence, one may not trivially transpose the LMC period-luminosity relation from one galaxy to the other.Comment: 13 pages, 23 figures. Accepted for publication in A&A

Illuminating hadron structure by scattering light on light

The results of an Amplitude Analysis of the world data on integrated and differential cross-sections on $\gamma\gamma\to\pi\pi$ are presented, following the publication of the Belle charged pion results.Comment: 5 pages, 7 figures. To appear in the Proceedings of the International Workshop on $e^+e^-$ collisions from $\phi$ to $\psi$, Frascati, April 2008. This version rewords the reference to the work of Achasov and Shestakov, with apologies to them for any misunderstandin

Long Period Variable Stars: galactic populations and infrared luminosity calibrations

In this paper HIPPARCOS astrometric and kinematic data are used to calibrate both infrared luminosities and kinematical parameters of Long Period Variable stars (LPVs). Individual absolute K and IRAS 12 and 25 luminosities of 800 LPVs are determined and made available in electronic form. The estimated mean kinematics is analyzed in terms of galactic populations. LPVs are found to belong to galactic populations ranging from the thin disk to the extended disk. An age range and a lower limit of the initial mass is given for stars of each population. A difference of 1.3mag in K for the upper limit of the Asymptotic Giant Branch is found between the disk and old disk galactic populations, confirming its dependence on the mass in the main sequence. LPVs with a thin envelope are distinguished using the estimated mean IRAS luminosities. The level of attraction (in the classification sense) of each group for the usual classifying parameters of LPVs (variability and spectral types) is examined.Comment: Accepted for publication in A&A (May 2001). 13 page

Cournon-d'Auvergne – Carré du Bois Joli

Identifiant de l'opération archéologique : 2006/11 et 62 Date de l'opération : 2006 (MH) Le diagnostic effectué en 2005, sous la responsabilité de Pierre Pouenat (BSR 2005, p. 97-98), sur le terroir nommé « Carré du Bois Joli », a couvert une superficie d’un peu moins de 10 ha, localisée en bordure est du « bassin de Sarliève » et à quelques centaines de mètres au nord de la fouille de la « Grande Halle d’Auvergne » (BSR 2001, p. 97-98, Gérard Vernet). Dans cette emprise, la zone basse et hum..

Stellar and circumstellar evolution of long period variable stars

In a first paper, HIPPARCOS astrometric and kinematic data were used to calibrate both infrared K and IRAS luminosities at the same time as kinematic parameters of Long Period Variable stars (LPVs). Individual estimated absolute magnitudes and a probabilistic assignation to galactic populations were deduced from these calibrations for each LPV of our sample. Here we propose a scenario of simultaneous stellar and circumstellar evolution according to the galactic populations. The transitory states of S and Tc stars allow us to confirm the location of the first dredge-up at $M_{bol}=-3.5$. There is also evidence suggesting that a previous enrichment in s-elements from a more evolved companion may accelerate the evolution along the AGB. The possible evolution to OH LPVs is included in this scenario, and any of these stars may have a mass at the limit of the capability for a C enrichment up to C/O > 1. A list of bright massive LPVs with peculiar envelope and luminosity properties is proposed as Hot Bottom Burning candidates. The He-shell flash star, R Cen, is found to be exceptionally bright and could become, before leaving the AGB, a C-rich LPV brighter than the usual luminosity limit of carbon stars.Comment: Accepted for publication in Astronomy & Astrophysic

Cournon-d'Auvergne – Les Plaines, ancien stade Gardet (immeubles d'habitation)

Identifiant de l'opération archéologique : 2005/229 et 266 - 2006/132 Date de l'opération : 2006 (MH) La démolition du stade « Gardet » et la reconstruction sur son emplacement d’un ensemble d’immeubles d’habitation ont occasionné la prescription d’une fouille archéologique, suite aux résultats positifs du diagnostic effectué l’année précédente (Ulysse Cabezuelo, 2005 - Cournon (63), Les Plaines. Rapport de diagnostic archéologique,INRAP, Clermont-Ferrand et BSR 2005, p. 96-97, Ulysse Cabezue..