3,927 research outputs found

    Masses and widths of the rho(770)

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    Isospin violation in the ρ(770)\rho(770) mass and width is considered within the SS matrix approach using combined fits to the e+eπ+πe^+e^- \to\pi^+\pi^- and τντππ0\tau^- \to \nu_{\tau}\pi^-\pi^0 data performed by the ALEPH collaboration. We show that the pole position following from the parameters obtained from the ALEPH fits are not sensitive to the details of the parametrization. In this context, we have found that the pole mass difference and the pole width difference between the charged and neutral ρ\rho are consistent with zero. We show that a one loop calculation including vector, axial vector and pseudo-scalar mesons can satisfactorily describe the observed isospin breaking. We also give an estimate for the mass difference between the neutral and charged states of the a1(1260)a_1(1260).Comment: 8 pages, 1 figur

    On Scale Invariance and Anomalies in Quantum Mechanics

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    We re-consider the quantum mechanics of scale invariant potentials in two dimensions. The breaking of scale invariance by quantum effects is analyzed by the explicit evaluation of the phase shift and the self-adjoint extension method. We argue that the breaking of scale invariance reported in the literature for the δ\delta(r) potential, is an example of explicit and not an anomaly or quantum mechanical symmetry breaking.Comment: 15 pp in latex, no figure

    Tests of flavor symmetry in J/psi decays

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    We use SU(3) flavor symmetry to analyze the PP,VPPP', VP and baryon-antibaryon decays of J/ψJ/\psi. Both, the SU(3)-invariant and -violating contributions are considered. Particular attention is paid to the interference of the electromagnetic and strong amplitudes.Comment: 8 pages, latex. Talk given at CAM-94 Physics Meetin

    Pion Scattering Revisited

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    Chiral Ward identities lead to consistent accounting for the sigma's width in the linear sigma model's Feynman rules. Reanalysis of pion scattering data at threshold imply a mass for the sigma of 600+ 200 - 100 MeV.Comment: latex; VIII EMPC (Oaxaca, Nov 98) Proceeding

    Effective SU(2)_L x U(1) theory and the Higgs boson mass

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    We assume the stability of vacuum under radiative corrections in the context of the standard electroweak theory. We find that this theory behaves as a good effective model already at cut off energy scales as low as 0.7 TeV. This stability criterion allows to predict m_H= 318 +- 13 GeV for the Higgs boson mass.Comment: Latex, 5 pages, 1 Postscript figure include