Light meson resonances from unitarized Chiral Perturbation Theory

We report on our recent progress in the generation of resonant behavior in unitarized meson-meson scattering amplitudes obtained from Chiral Perturbation Theory. These amplitudes provide simultaneously a remarkable description of the resonance region up to 1.2 GeV as well as the low energy region, since they respect the chiral symmetry expansion. By studying the position of the poles in these amplitudes it is possible to determine the mass and width of the associated resonances, as well as to get a hint on possible classification schemes, that could be of interest for the spectroscopy of the scalar sector.Comment: Invited talk to the II International Workshop on Hadron Physics & Effective Theories of Low Energy QCD. 25-29 September 2002. Coimbra. Portuga

Meson resonances from unitarized meson scattering at one loop in Chiral Perturbation Theory

We show the results for the scattering poles associated to the rho, f0, a0, K*, sigma and kappa resonances in meson-meson scattering. Our amplitudes are obtained from the complete one-loop meson-meson scattering amplitudes from Chiral Perturbation Theory. Once unitarized with the Inverse Amplitude Method, they describe remarkably well the data simultaneously in the low energy and resonance regions up to 1.2 GeV, using low energy parameters compatible with present determinations.Comment: To appear in the proceedings of the 5th International Conference on ``Quark confinement and the hadron spectrum'', held in Gargnano, Garda Lake, Italy. 10-14th September 2002. 3 page

Unitarization of the complete meson-meson scattering at one loop in Chiral Perturbation Theory

We report on our one-loop calculation of all the two meson scattering amplitudes within SU(3) Chiral Perturbation Theory, i.e. with pions, kaons and etas. Once the amplitudes are unitarized with the coupled channel Inverse Amplitude Method, they satisfy simultaneously the correct low-energy chiral constraints and unitarity. We obtain a remarkable description of meson-meson scattering data up to 1.2 GeV including the scattering lengths and seven light resonances.Comment: To appear in the proceedings of QCD@work: International Workshop on QCD: Theory and Experiment. Martina Franca (Italy) June 16-20. 200

Complete meson-meson scattering within one loop in Chiral Perturbation Theory: Unitarization and resonances

We review our recent one-loop calculation of all the two meson scattering amplitudes within SU(3) Chiral Perturbation Theory, i.e. with pions, kaons and etas. By unitarizing these amplitudes we are able to generate dynamically the lightest resonances in meson-meson scattering. We thus obtain a remarkable description of the meson-meson scattering data right from threshold up to 1.2 GeV, in terms of chiral parameters in good agreement with previous determinations.Comment: 4 pages, To appear in the Proceedings of the IX International Conference on Hadron Spectroscopy, HADRON2001, IHEP, Protvino, Russia, August 200

Rho and Sigma Mesons in Unitarized Thermal ChPT

We present our recent results for the rho and sigma mesons considered as resonances in pion-pion scattering in a thermal bath. We use chiral perturbation theory to fourth order in p for the low energy behaviour, then extend the analysis via the unitarization method of the Inverse Amplitude into the resonance region. The width of the rho broadens about twice the amount required by phase space considerations alone, its mass staying practically constant up to temperatures of order 150 MeV. The sigma meson behaves in accordance to chiral symmetry restoration expectations.Comment: Proc. Workshop Strong and Electroweak Matter 02, Heidelberg, German

Thermal Instability in a Cooling and Expanding Medium Including Self-Gravity and Conduction

A systematic study of the linear thermal stability of a medium subject to cooling, self-gravity and thermal conduction is carried out for the case when the unperturbed state is subject to global cooling and expansion. A general, recursive WKB solution for the perturbation problem is obtained which can be applied to a large variety of situations in which there is a separation of time-scales for the different physical processes. Solutions are explicitly given and discussed for the case when sound propagation and/or self-gravity are the fastest processes, with cooling, expansion and thermal conduction operating on slower time-scales. A brief discussion is also added for the solutions in the cases in which cooling or conduction operate on the fastest time-scale. The general WKB solution obtained in this paper permits solving the problem of the effect of thermal conduction and self-gravity on the thermal stability of a globally cooling and expanding medium. As a result of the analysis, the critical wavelength (often called Field length) above which cooling makes the perturbations unstable against the action of thermal conduction is generalized to the case of an unperturbed background with net cooling. As an astrophysical application, the generalized Field length is calculated for a hot (10^4 - 10^8 K), optically thin medium (as pertains, for instance, for the hot interstellar medium of SNRs or superbubbles) using a realistic cooling function and including a weak magnetic field. The stability domains are compared with the predictions made on the basis of models for which the background is in thermal equilibrium. The instability domain of the sound waves, in particular, is seen to be much larger in the case with net global cooling.Comment: 36 pages, 6 figures, accepted by ApJ, probable publication date: April 20, 200

A Decadal Inversion of CO2 Using the Global Eulerian-Lagrangian Coupled Atmospheric Model (GELCA): Sensitivity to the Ground-Based Observation Network

We present an assimilation system for atmospheric carbon dioxide (CO2) using a Global Eulerian-Lagrangian Coupled Atmospheric model (GELCA), and demonstrate its capability to capture the observed atmospheric CO2 mixing ratios and to estimate CO2 fluxes. With the efficient data handling scheme in GELCA, our system assimilates non-smoothed CO2 data from observational data products such as the Observation Package (ObsPack) data products as constraints on surface fluxes. We conducted sensitivity tests to examine the impact of the site selections and the prior uncertainty settings of observation on the inversion results. For these sensitivity tests, we made five different sitedata selections from the ObsPack product. In all cases, the time series of the global net CO2 flux to the atmosphere stayed close to values calculated from the growth rate of the observed global mean atmospheric CO2 mixing ratio. At regional scales, estimated seasonal CO2 fluxes were altered, depending on the CO2 data selected for assimilation. Uncertainty reductions (URs) were determined at the regional scale and compared among cases. As measures of the model-data mismatch, we used the model-data bias, root-mean-square error, and the linear correlation. For most observation sites, the model-data mismatch was reasonably small. Regarding regional flux estimates, tropical Asia was one of the regions that showed a significant impact from the observation network settings. We found that the surface fluxes in tropical Asia were the most sensitive to the use of aircraft measurements over the Pacific, and the seasonal cycle agreed better with the results of bottom-up studies when the aircraft measurements were assimilated. These results confirm the importance of these aircraft observations, especially for constraining surface fluxes in the tropics

Validation of the IASI operational CH4 and N2O products using ground-based Fourier Transform Spectrometer: preliminary results at the Izaña Observatory (28ºN, 17ºW)

Within the project VALIASI (VALidation of IASI level 2 products) the validation of the IASI operational atmospheric trace gas products (total column amounts of H2O, O3, CH4, N2O, CO2 and CO as well as H2O and O3 profiles) will be carried out. Ground-based FTS (Fourier Transform Spectrometer) trace gas measurements made in the framework of NDACC (Network for the Detection of Atmospheric Composition Change) will serve as the validation reference. In this work, we present the validation methodology developed for this project and show the first intercomparison results obtained for the Izaña Atmospheric Observatory between 2008 and 2012. As an example, we focus on two of the most important greenhouse gases, CH4 and N2O