Present Status of Chiral Perturbation Theory

The basic ideas and methods of chiral perturbation theory are briefly reviewed. I discuss the recent attempts to build an effective Lagrangian in the resonance region and summarize the known large-N_C constraints on the low-energy chiral couplings.Comment: 6 pages. Invited talk at the 10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2004), Beijing, China, August 29 - September 4, 200

Form-factors and current correlators: chiral couplings L_10(mu) and C_87(mu) at NLO in 1/N(C)

Using the resonance chiral theory Lagrangian, we perform a calculation of the vector and axial-vector two-point functions at the next-to-leading order (NLO) in the 1/N(C) expansion. We have analyzed these correlators within the single-resonance approximation and have also investigated the corrections induced by a second multiplet of vector and axial-vector resonance states. Imposing the correct QCD short-distance constraints, one determines the difference of the two correlators Pi(t) = Pi_VV(t)- Pi_AA(t) in terms of the pion decay constant and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L_10 and C_87 at NLO, keeping full control of their renormalization scale dependence. At mu_0=0.77 GeV, we obtain L_10(mu_0) = (-4.4 \pm 0.9)10^{-3} and C_87^r(mu_0)=(3.1 \pm 1.1)10^{-5}

Problemática actual y futura de la Sedimentología en España

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Towards a determination of the chiral couplings at NLO in 1/N(C): L_8(mu) and C_38(mu)

We present a dispersive method which allows to investigate the low-energy couplings of chiral perturbation theory at the next-to-leading order (NLO) in the 1/N(C) expansion, keeping full control of their renormalization scale dependence. Using the resonance chiral theory Lagrangian, we perform a NLO calculation of the scalar and pseudoscalar two-point functions, within the single-resonance approximation. Imposing the correct QCD short-distance constraints, one determines their difference Pi(t)=Pi_S(t)-Pi_P(t) in terms of the pion decay constant and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L_8 and C_38. At mu_0=0.77 GeV, we obtain L_8(mu_0)^{SU(3)} = (0.6+-0.4)10^{-3} and C_{38}(mu_0)^{SU(3)}=(2+-6)10^{-6}.Comment: Extended version published at JHEP01(2007)039. A NLO prediction for the O(p6) chiral coupling C_38 has been added. The original L_8 results remain unchange

The Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment: Where do we stand?

We review the status of the hadronic light-by-light contribution to the muon anomalous magnetic moment and critically compare recent calculations. We also study in detail which momentum regions the pi^0 exchange main contribution originates. We also argue that a_\mu^{light-by-light} = (11 \pm 4) \times 10^{-10} encompasses the present understanding of this contribution and comment on some directions to improve on that.Comment: 16 pages, 9 figure

The impact of socioeconomic characteristics on CO₂ emissions associated with urban mobility: Inequality across individuals

Concerns about the unequal distribution of greenhouse gas emissions attributable to mobility are gaining increasing attention in scholarly analyses as well as in the public policy arena. The factors influencing the emissions of individuals are largely undocumented, but they are assumed to be the same for all, be they low or high emitters. We use a household travel survey conducted in the metropolitan area of Barcelona to differentiate the factors that result in different rates of emission. It shows that the top 10% of emitters produce 49% of total emissions while ‘non-daily’ emitters make up 38.5% of the sample. We adopt a quantile regression approach, which reveals significant socioeconomic differences between groups of emitters. Gender, income and home-municipality type are influential in accounting for CO2 emissions for all groups. Educational level appears to be less significant, and occupation shows no significance at all. The study confirms the ineffective nature of toll policy design in the area. Overall, socioeconomic factors have different impacts on different emitting groups, but these characteristics do not impact equally across all the population. Quantile regression using mobility survey data gathered from various cities would provide useful evidence for improving the design of urban mobility policies

Algunas aportaciones a la estratigrafía de Silúrico-Devónico de "las nogueras" al E. de Gerri de la Sal (Lérida)

La presente nota trata sobre la estratigrafía de la parte alta del Silúrico y del Devónico de la hoja 1/50.000 de Tremp (n.O 252). Se estudian dos series detalladas de los materiales silúricos aflorados y de los tramos inferiores del Devónico y se propone una serie total para el Devónico de la zona, como resultado de síntesis de la cartografía de las facies del ángulo nordeste de la inencionada hoja y de numerosos cortes estratigráficos de detalle