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 $D^*\pi\pi$ 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.Comment: latex, 6 page

Vacuum Energy Density in the Quantum Yang - Mills Theory

Using the effective potential approach for composite operators, we have formulated a general method of calculation of the truly non-perturbative Yang-Mills vacuum energy density (this is, by definition, the Bag constant apart from the sign). It is the main dynamical characteristic of the QCD ground state. Our method allows one to make it free of the perturbative contributions ('contaminations'), by construction. We also perform an actual numerical calculation of the Bag constant for the confining effective charge. Its choice uniquely defines the Bag constant, which becomes free of all the types of the perturbative contributions now, as well as possessing many other desirable properties as colorless, gauge independence, etc. Using further the trace anomaly relation, we develop a general formalism which makes it possible to relate the Bag constant to the gluon condensate not using the weak coupling solution for the corresponding $\beta$ function. Our numerical result for the Bag constant shows a good agreement with other phenomenological estimates of the gluon condensate.Comment: 28 pages and 4 figures, typos corrected, added new appendices and new references in comparison with the published versio

Standard Model CP-violation and Baryon asymmetry

Simply based on CP arguments, we argue against a Standard Model explanation of the baryon asymmetry of the universe in the presence of a first order phase transition. A CP-asymmetry is found in the reflection coefficients of quarks hitting the phase boundary created during the electroweak transition. The problem is analyzed both in an academic zero temperature case and in the realistic finite temperature one. The building blocks are similar in both cases: Kobayashi-Maskawa CP-violation, CP-even phases in the reflection coefficients of quarks, and physical transitions due to fermion self-energies. In both cases an effect is present at order $\alpha_W^2$ in rate. A standard GIM behaviour is found as intuitively expected. In the finite temperature case, a crucial role is played by the damping rate of quasi-particles in a hot plasma, which is a relevant scale together with $M_W$ and the temperature. The effect is many orders of magnitude below what observation requires, and indicates that non standard physics is indeed needed in the cosmological scenario.Comment: 15p, LaTeX (3figs incl.), CERN 93/7081,LPTHE Orsay-93/48,HUTP-93/A036,HD-THEP-93-4

Standard Model CP-violation and Baryon asymmetry Part II: Finite Temperature

We consider the scattering of quasi-particles off the boundary created during a first order electroweak phase transition. Spatial coherence is lost due to the quasi-quark damping rate, and we show that reflection on the boundary is suppressed, even at tree-level. Simply on CP considerations, we argue against electroweak baryogenesis in the Standard Model via the charge transport mechanism. A CP asymmetry is produced in the reflection properties of quarks and antiquarks hitting the phase boundary. An effect is present at order $\alpha_W^2$ in rate and a regular GIM behaviour is found, which can be expressed in terms of two unitarity triangles. A crucial role is played by the damping rate of quasi-particles in a hot plasma, which is a relevant scale together with $M_W$ and the temperature. The effect is many orders of magnitude below what observation requires.Comment: 44 pages, CERN-TH.7263/94, LPTHE Orsay-94/49, HUTP-94/A015, HD-THEP-94-20, FTUAM-94/14, NSF-ITP-94-6

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