2,802 research outputs found
Quantum loops in the Resonance Chiral Theory: improving the vector form factor
Quantum loops in the Resonance Chiral Theory are needed to improve the
implementation of non-perturbative QCD. Furthermore, the one-loop computations
can predict chiral low-energy couplings at next-to-leading order, a very
appealing task. We present a first calculation of the vector form factor of the
pion at subleading order in the 1/N_C expansion. From the analysis of the
result at large energies we justify the requirement of considering
short-distance constraints from form factors with resonances in the final
state. The long-distance limit of our results allows to get a next-to-leading
order estimate of \ell_6.Comment: Talk given at the International Workshop e+e- Collisions from phi to
J/psi, 27th February-2nd March (2006), Novosibirsk (Russia
Enhancement of collagen deposition and cross-linking by coupling lysyl oxidase with bone morphogenetic protein-1 and its application in tissue engineering
Cultured cell-derived extracellular matrices (ECM)-based biomaterials exploit the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, standard cell culture conditions are far from ideal given the fact that the diluted microenvironment does not favor the production of ECM components, a circumstance particularly relevant for collagen. An incomplete conversion of procollagen by C-proteinase/bone morphogenetic protein 1 (BMP1) has been proposed to severely limit in vitro collagen deposition. BMP1 also catalyzes the proteolytic activation of the precursor of the collagen cross-linking enzyme, lysyl oxidase (LOX) to yield the active form, suggesting a deficit in cross-linking activity under standard conditions. We hypothesized that the implementation of fibroblast cultures with LOX and BMP1 may be an effective way to increase collagen deposition. To test it, we have generated stable cell lines overexpressing LOX and BMP1 and studied the effect of supernatants enriched in LOX and BMP1 on collagen synthesis and deposition from fibroblasts. Herein, we demonstrate that the supplementation with LOX and BMP1 strongly increased the deposition of collagen onto the insoluble matrix at the expense of the soluble fraction in the extracellular medium. Using decellularization protocols, we also show that fibroblast-derived matrices regulate adipogenic and osteogenic differentiation of human mesenchymal stem cells (MSC), and this effect was modulated by LOX/BMP1. Collectively, these data demonstrate that we have developed a convenient protocol to enhance the capacity of in vitro cell cultures to deposit collagen in the ECM, representing this approach a promising technology for application in tissue engineeringTis work was supported by grants from Ministerio de Economía y Competitividad (Plan Nacional de I+D+I: SAF2012-34916, and SAF2015-65679-R to F.R-P
One-loop Renormalization of Resonance Chiral Theory with Scalar and Pseudoscalar Resonances
The divergent part of the generating functional of the Resonance Chiral
Theory is evaluated up to one loop when one multiplet of scalar an pseudoscalar
resonances are included and interaction terms which couple up to two resonances
are considered. Hence we obtain the renormalization of the couplings of the
initial Lagrangian and, moreover, the complete list of operators that make this
theory finite, at this order.Comment: 4 pages, no figures. Talk given at the High-Energy Physics
International Conference on Quantum Chromodynamics, 2-9 July (2005),
Montpellier (France). To appear in the Proceeding
Renormalization group equations in resonance chiral theory
The use of the equations of motion and meson field redefinitions allows the
development of a simplified resonance chiral theory lagrangian: terms including
resonance fields and a large number of derivatives can be reduced into
corresponding O(p2) resonance operators, containing the lowest possible number
of derivatives. This is shown by means of the explicit computation of the pion
vector form-factor up to next-to-leading order in 1/Nc. The study of the
renormalization group equations for the corresponding couplings demonstrates
the existence of an infrared fixed point in the resonance theory. The
possibility of developing a perturbative 1/Nc expansion in the slow running
region around the fixed point is shown here.Comment: 6 pages, 3 figures. Final version as published. References added.
Extended explanations. The interrelation between the IR fixed point and the
UV constraints has been further studie
Renormalizable Sectors in Resonance Chiral Theory: S -> pi pi Decay Amplitude
We develop a resonance chiral theory without any a priori limitation on the
number of derivatives in the hadronic operators. Through an exhaustive analysis
of the resonance lagrangian and by means of field redefinitions, we find that
the number of independent operator contributing to the S -> pi pi decay
amplitude is finite: there is only one single-trace operator (the cd term) and
three multi-trace terms. The deep implication of this fact is that the
ultraviolet divergences that appear in this amplitude at the loop level can
only appear through these chiral invariant structures. Hence, a renormalization
of these couplings renders the amplitude finite.Comment: 4 page
On the structure of two-point Green-functions at next-to-leading order in 1/Nc
The structure of the two-point QCD Green-functions is studied in this note in
the limit of large number of colours. Their general form at next-to-leading
order in 1/Nc is derived keeping the infinite resonance summation and without
relying on a particular realization of the hadronic action. It is found that
the contributions from chiral operators without resonance fields of order p^4
or higher are irrelevant for the computation of the correlators and, hence,
they can be dropped at the beginning of the calculation. The possibility of a
more general cancelation of these local terms at the level of the generating
functional is discussed.Comment: 6 pages, 1 figur
Vanishing chiral couplings in the large-N_C resonance theory
The construction of a resonance theory involving hadrons requires
implementing the information from higher scales into the couplings of the
effective Lagrangian. We consider the large-Nc chiral resonance theory
incorporating scalars and pseudoscalars, and we find that, by imposing LO
short-distance constraints on form factors of QCD currents constructed within
this theory, the chiral low-energy constants satisfy resonance saturation at
NLO in the 1/Nc expansion.Comment: 5 pages, 2 figures. Version published in Physical Review D. Some
equations to facilitate the discussion have been adde
Current correlators and form factors in the resonance region
Within Resonance Chiral Theory and in the context of QCD current correlators
at next-to-leading order in 1/N(C), we have analyzed the two-body form factors
which include resonances as a final state . The short-distance constraints have
been studied. One of the main motivations is the estimation of the chiral
low-energy constants at subleading order, that is, keeping full control of the
renormalization scale dependence. As an application we show the resonance
estimation of some coupling, L(10)(mu_0)=(-4.4 \pm 0.9)10^{-3} and
C(87)(mu_0)=(3.1 \pm 1.1)10^{-5}.Comment: Talk given at the 14th International Quantum Chromodynamics
Conference, 7-12th July (2008), Montpellier (France
Pion and Kaon Decay Constants: Lattice vs. Resonance Chiral Theory
The Lattice results for the pion and kaon decay constants are analysed within
the Resonance Chiral Theory framework in the large NC limit. The approximately
linear behaviour of the observable at large light-quark mass is explained
through the interaction with the lightest multiplet of scalar resonances. The
analysis of the Lattice results allows to obtain the resonance mass MS=1049 +-
25 MeV and the Chiral Perturbation Theory parameters at leading order in 1/NC.Comment: 10 pages, 2 figure
Інформаційна культура й професійно-особистісний розвиток майбутнього вчителя історії
(uk) У статті розглядається ціннісно-мотиваційний компонент та прояв індивідуальності в структурі інформаційної культури майбутнього вчителя історії.(ru) В статье рассматривается ценностно-мотивационный компонент и проявление индивидуальности в структуре информационной культуры будущего учителя истории
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