arXiv subjects

Oscar Cata

Publications and source records attributed to Oscar Cata.

40 records · Page 3Linked to original sources

arXiv2006

The operator product expansion does not imply parity doubling of hadrons

We examine whether the fact that QCD is chirally invariant at short distances necessarily leads to the prediction that hadrons form approximate parity doublets, as has been recently put forward by Glozman and collaborators. We show that this is not the case, and we exhibit some of the pitfalls of trying to link the operator product expansion to the hadron spectrum. We illustrate our arguments within a model for scalar and pseudo-scalar mesons used recently by Shifman to argue for parity doubling. We find that, whatever the experimental situation may be, there is no theoretical basis for parity doubling based on the use of the operator product expansion.

hep-ph↗

arXiv2005

Meson Electroweak Interactions in Multicolor Quantum Chromodynamics

This PhD Thesis is mainly devoted to the study of hadronic matrix elements of kaons. Its inner structure can be divided in three parts. In Chapter 3 we address the issue of quantum corrections in Resonance Chiral Lagrangians with the aid of the 1/N_c expansion. We compute, as an illustrative example, the coupling L_10 to one loop. Chapters 4 and 5 are the main body of the present work and deal with the determination of the relevant parameters in kaon phenomenology. We give a value for the invariant B_K, the kaon mass difference and ε_K in a model-independent way, paying special attention to the issue of scale and scheme independence. In our approach, this is achieved in a very natural way once matching between long and short distances is ensured. We end up with a final chapter on the subject of duality violations in the VV-AA two-point correlator.

hep-ph↗

arXiv2005

Impact of Duality Violations on Spectral Sum Rule Analyses

Recent sum rule analyses on the two-point correlator have led to significant discrepancies in the values found for the OPE condensates, most dramatically in the dimension eight condensate and to a lesser extent in the dimension six one. Precise knowledge of these condensates is of relevance in kaon decays and therefore it seems mandatory to assess the actual impact of what is commonly neglected in spectral sum rules, most prominently the issue of duality violations. We will explicitly compute them in a toy model and show that they are a priori non-negligible.

hep-ph↗

arXiv2002

Application of the Large-N_c limit to a Chiral Lagrangian with Resonances

It is shown that the implementation of the Large--$N_c$ approximation helps to get insight into the structure of, in principle, any QCD-like theory. As an example, we will compute the NLO corrections to $L_{10}$ in the chiral limit with a Lagrangian with Resonances.

hep-ph↗