arXiv subjects

J. Morales

Publications and source records attributed to J. Morales.

58 records · Page 4Linked to original sources

arXiv1997

Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer

Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of $g_{aγγ} < 2.7\cdot 10^{-9}$ GeV$^{-1}$, independent of axion mass up to ~ 1 keV.

astro-ph↗

arXiv1996

Higgs Physics in the Large N limit

In this paper we study the large N limit of the Standard Model Higgs sector with $Nλ$, $Ng^2$ and $Ng'^2$ constant and $N$ being the number of would-be Goldstone bosons. Despite the simplicity of this method at leading order, its results satisfy simultaneously important requirements such as unitarity and the low-energy theorems in contrast with other more conventional approaches. Moreover, it is fully compatible with the Equivalence Theorem and it yields a consistent description of the Higgs boson mass and width. Finally we have also included a phenomenological discussion concerning the applications of this method to the LHC.

hep-ph↗

arXiv1995

A note on the GG-->PI 0 PI 0 reaction in the 1/N expansion of ChPT

In this work we present the results of a complete calculation of the $γ γ\rightarrow π^0π^0$ amplitude to leading order in the large $N$ approximation ($N$ being the number of Goldstone bosons) up to order $m^2_π/F^2$. The amplitude turns to be proportional to that of $π^+π^-\rightarrow π^0π^0$. In spite of the fact that this factorization property cannot hold in general (as it was recently pointed out by Morgan and Penington), it appears here since in the large $N$ limit only the $I=J=0$ channel contributes to the $γγ\rightarrow π^0π^0$ reaction. Moreover it seems to be a reasonable approximation in this case since it is possible to reproduce, as a prediction, the experimental data starting from a one-parameter fit of the $ππ$ scattering data.

hep-ph↗

arXiv1994

Pion Mass Effects in the Large $N$ Limit of $\chiPT$

We compute the large $N$ effective action of the $O(N+1)/O(N)$ non-linear sigma model including the effect of the pion mass to order $m^2_π/f_π^2$. This action is more complex than the one corresponding to the chiral limit not only because of the pion propagators but also because chiral symmetry produce new interactions proportional to $m^2_π/f_π^2$. We renormalize the action by including the appropriate counter terms and find the renormalization group equations for the corresponding couplings. Then we estudy the unitarity propierties of the scattering amplitudes. Finally our results are applied to the particular case of the linear sigma model and also are used to fit the pion scattering phase shifts.

hep-ph↗