Partially Quenched Chiral Perturbation Theory to NNLO

This paper summarizes the recent calculations of the masses and decay constants of the pseudoscalar mesons at the two-loop level, or NNLO, in Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications include chiral extrapolations of Lattice QCD, as well as the determination of the low-energy constants (LEC:s) of QCD.Comment: To appear in the proceedings of PANIC 200

Partially Quenched and Three Flavour ChPT at Two Loops

A summary of recent progress in Chiral Perturbation Theory (ChPT) at the two-loop level is given. A short introduction to ChPT is included, along with an explanation of the usefulness of developing ChPT for partially quenched QCD. Further, our recent work in partially quenched ChPT is reviewed, and a few comments are given on older work in mesonic ChPT at the two-loop level. In particular, we quote the present best values for the low-energy constants of the $\mathcal{O}(p^4)$ chiral Lagrangian.Comment: 11 pages, invited talk at ``Final Euridice Meeting'', August 24-28 2006, Kazimierz, Polan

Electromagnetic Corrections in Partially Quenched Chiral Perturbation Theory

We introduce photons in Partially Quenched Chiral Perturbation Theory and calculate the resulting electromagnetic loop-corrections at NLO for the charged meson masses and decay constants. We also present a numerical analysis to indicate the size of the different corrections. We show that several phenomenologically relevant quantities can be calculated consistently with photons which couple only to the valence quarks, allowing the use of gluon configurations produced without dynamical photons.Comment: 11 page

Three-Flavor Partially Quenched Chiral Perturbation Theory at NNLO for Meson Masses and Decay Constants

We discuss Partially Quenched Chiral Perturbation Theory (PQ$\chi$PT) and possible fitting strategies to Lattice QCD data at next-to-next-to-leading order (NNLO) in the mesonic sector. We also present a complete calculation of the masses of the charged pseudoscalar mesons, in the supersymmetric formulation of PQ$\chi$PT. Explicit analytical results are given for up to three nondegenerate sea quark flavors, along with the previously unpublished expression for the pseudoscalar meson decay constant for three nondegenerate sea quark flavors. The numerical analysis in this paper demonstrates that the corrections at NNLO are sizable, as expected from earlier work.Comment: 31 pages, numerical discussion extended including convergence NLO to NNL

The Pseudoscalar Meson Mass to Two Loops in Three-Flavor Partially Quenched χ\chiPT

This paper presents a first study of the pseudoscalar meson masses to two loops, or NNLO, within the supersymmetric formulation of partially quenched chiral perturbation theory (PQ$\chi$PT). The expression for the pseudoscalar meson mass in the case of three valence and three sea quarks with equal masses, but different from each other, is given to ${\cal O}(p^6)$, along with a numerical analysis.Comment: 4 pages, one reference added, small changes in discussio

Meson Properties in Partially Quenched Effective Field Theory

Mass corrections and decay constants for light mesons have been calculated in Partially Quenched Chiral Perturbation Theory. The calculations of the charged meson masses have been performed to third order, first for degenerate quark masses, and then, in a second project, for the general case. Another calculation also shows that a resummation of unphysical double poles in the neutral propagators of the partially quenched theory allows for the determination of the low-energy constants needed to determine the physical eta mass. Finally, electromagnetic corrections are included into the theory as dynamical fields and their effects on the masses and decay constants of the charged mesons have been calculated to second order. Some consequences concerning the fitting of these results to Lattice QCD simulations are also considered

Prissättning av musik vid digital distribution

Bakgrund: De senaste åren har alltmer musik börjat distribueras digitalt via Internet. Detta har framförallt skett via fildelningsnätverk men under de senaste två åren har allt fler legala tjänster växt fram. Prisnivån hos dessa tjänster är väldigt enhetlig och återförsäljarna har små marginaler på sin försäljning. Teorier påstår att Internet ger möjligheten att skära bort delar i distributionskedjan och det kan leda till lägre priser. Internet ger också ökade möjligheter att ändra priser på daglig basis. Syfte: Det övergripande syftet med uppsatsen är att identifiera och söka förklaringar till prissättningen av musik vid digital distribution. Metod: Undersökningen har genomförts via 7 personliga intervjuer, 1 telefonintervju och 3 e-mailintervjuer med personer som arbetar i musikbranschen. Dessutom har en enkätundersökning genomförts där 200 studenter från Linköpings universitet deltog. Resultat: Distributionskedjan kommer inte att kortas av, och det är inte troligt att den nya distributionsformen leder till lägre priser. Transaktionsavgifterna är mycket höga i dagsläget och om dessa avgifter sänks finns det utrymme för prissänkningar. Eftersom Internet ger möjligheter att ändra priser på daglig basis borde musikbranschen använda prissättningen på ett mer dynamiskt sätt genom olika prisstrategier såsom exempelvis skummning och penetrering. Det kommer också att bli mycket viktigt för musikbranschen att försöka skapa ett värde i den digitala musikdistributionen, något som kunden är beredd att betala för. Studenterna i Linköping har god kännedom av musiknedladdning men deras vilja att betala för musiken är begränsad. Studenter är troligtvis en mer priskänslig grupp är förvärvsarbetande personer

eta Mass and NNLO three-flavor partially quenched chiral perturbation theory

We show how to resum neutral propagators to all orders in partially quenched chiral perturbation theory. We calculate the relevant quantities to next-to-next-to-leading order (NNLO). Using these results we show how to extend the proposal by Sharpe and Shoresh for determining the parameters relevant for the eta mass from partially quenched lattice QCD calculations to NNLO

Strong association between earlier abuse and revictimization in youth Strong association between earlier abuse and revictimization in youth

Abstract Background: Violence victimization among youth is recognized as a public health problem. The objective was to analyze the risk pattern of emotional, physical, and sexual abuse during the past 12 months by gender, sociodemographic factors, health risk behaviors, and exposure to abuse before the age of 15, among young men and women attending youth health centers in Sweden. Methods: A cross-sectional survey was conducted using a nationally representative sample of youth health centers. A total of 2,250 young women and 920 young men aged 15-23 completed a self-administered questionnaire. Odds ratios (OR) and adjusted odds ratios (AOR) with 95% CI were calculated. Results: A consistent and strong association was noted between exposure to all types of violence during the past year and victimization before the age of 15 for all types of violence for both women and men. The only exceptions were childhood sexual victimization and sexual violence during the past year for men. Younger age was associated with all violence exposure for the women and with emotional violence for the men. For the women, drug use was associated with all types of violence, while the association with hazardous alcohol use and not living with parents was restricted to physical and sexual violence exposure, present smoking was restricted to emotional and physical violence exposure, and partnership and living in urban areas were restricted to sexual violence. For men, not being partnered, hazardous alcohol consumption, and drug use meant increased risk for physical violence, while smoking and living in urban areas were associated with sexual violence. After adjustment, immigration had no association with violence exposure. Conclusions: Violence victimization in young men and women is often not a single experience. Findings underline the importance of early interventions among previously abused youth