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O. Pene

Publications and source records attributed to O. Pene.

38 records · Page 3Linked to original sources

Is the resonance D(2637) really a radial excitation?

We consider various possible identifications of the quantum numbers of the resonance D(2637) recently observed by DELPHI in the $D^*ππ$ channel. We argue that in spite of a good agreement of the measured mass with the quark-model prediction for the radial excitation, a total width as small as $\le 15$ MeV is hardly compatible with its identification as a radial charm excitation. The $J^{P}=2^{-}, 3^{-}$ orbitally excited mesons with such a mass could have widths of the observed order of magnitude. However in this case one would expect two neighbouring states with the mass difference of about 30-50 MeV corresponding to the nearly degenerate components of the heavy- meson multiplet with light-quanta angular momentum j=5/2, and moreover, according to the quark-model predictions the mass of the orbital excitation should be more than 50 MeV larger than 2637 MeV. Thus we conclude that, at present, we find no fully convincing understanding of the quantum numbers of the observed resonance.

hep-ph↗

The Fading of Symmetry Non-restoration at Finite Temperature

The fate of symmetries at high temperature determines the dynamics of the very early universe. It is conceivable that temperature effects favor symmetry breaking instead of restoration. Concerning global symmetries, the non-linear sigma model is analyzed in detail. For spontaneously broken gauge symmetries, we propose the gauge boson magnetic mass as a ``flag'' for symmetry (non)-restoration. We consider several cases: the standard model with one and two Higgs doublets in the perturbative regime, and the case of a strongly interacting Higgs sector. The latter is done in a model independent way with the tools provided by chiral Lagrangians. Our results clearly point towards restoration, a pattern consistent with recent lattice computations for global symmetries. In addition, we explicitly verify $BRST$ invariance for gauge theories at finite temperature.

hep-ph↗