2,696 research outputs found

    Theories of Non-Experiments in Coherent Decays of Neutral Mesons

    Full text link
    Many theoretical calculations of subtle coherent effects in quantum mechanics do not carefully consider the interface between their calculations and experiment. Calculations for gedanken experiments using initial states not satisfied in realistic experiments give results requiring interpretation. Confusion and ambiguities frequently arise. Calculations for time-dependent mixing oscillations describe non-experiments. Physical experiments describe oscillations in space in the laboratory system resulting from interference between waves having the same energy and time dependence; notnot different momenta and space dependence. Time-dependent oscillations are not observed.Comment: 8 page

    Systematics of Large Axial Vector Meson Production in Heavy Flavor Weak Decays

    Get PDF
    Branching ratios observed for DD and B decays to final states a1(1260)±Xa_1(1260)^{\pm} X are comparable to those for corresponding decays to π±X\pi^{\pm} X and ρ±X\rho^{\pm} X and much larger than those for all other decays. Implications are discussed of a "vector-dominance model" in which a WW is produced and immediately turns into an axial vector, vector or pseudoscalar meson. Data for decays to all such final states are shown to have large branching ratios and satisfy universality relations. Upper limits on small strong phase differences between amplitudes relevant to CP violation models are obtained from analysis of the predicted and observed suppression of BoB^o decays into neutral final states πoXo\pi^o X^o, ρoXo\rho^oX^o and a1oXoa_1^o X^o. . Branching ratios of 1\approx 1% are predicted for the as yet unobserved presence of the Ds1(2536)D_{s1}(2536) charmed-strange axial vector in B decays.Comment: 14 page

    What is coherent in neutrino oscillations

    Get PDF
    Simple rigorous quantum mechanics with no hand waving nor loopholes clarifies the confusion between three contradictory descriptions of neutrino oscillations: (1)The time oscillations shown in standard textbooks produced by neutrino eigenstates with different masses and different energies. (2) That time oscillations and interference between states having different energies cannot be observed in realistic experiments. (3) That interference between different neutrino mass eigenstates is not observable in "missing mass" experiments where information determining the neutrino mass is available from other particles measured in production or detection vertices. Quantum-mechanical ignorance of the neutrino momentum is rigorously shown to be imposed by all realistic detectors and to produce coherence between amplitudes from neutrino states with the same energy and different masses. Conditions are precisely formulated for the loss of coherence when mass eigenstate wave packets moving with different velocities separate. The example of Bragg scattering shows how quantum-mechanically imposed ignorance produces coherence.Comment: 13 pages, Abstract and text of original contribution completely revise

    How to Use Weak Decays in Analyses of Data on Nucleon Spin Structure Functions

    Get PDF
    The use of weak decays to determine proton spin structure is examined in view of possible violations of the Bjorken and Gottfried Sum rules, flavor symmetry breaking and flavor asymmetry in the sea. The use of the neutron decay is found to be unaffected by all these. A method for including these effects in analyses of hyperon decays shows that a flavor-asymmetric sea produced by SU(3) symmetry breaking has only a small effect on results for the total spin carried by quarks. However the strange quark contribution cannot be reliably obtained from charged lepton scattering and weak decay data alone, and requires additional model-dependent input relating nucleon and hyperon wave functions.Comment: 10 pages, Weizmann Report WIS-94/24/May-PH, Tel Aviv Report TAUP 2165-9

    Puzzles in Hyperon, Charm and Beauty Physics

    Get PDF
    Puzzles awaiting better experiments and better theory include: (1) the contradiction between good and bad SU(3) baryon wave functions in fitting Cabibbo theory for hyperon decays, strangeness suppression in the sea and the violation of the Gottfried Sum rule - no model fits all; (2) Anomalously enhanced Cabibbo-suppressed D+K+(sdˉ)D^+ \to K^{*+}(s\bar d) decays; (3) anomalously enhanced and suppressed BηXB \to \eta' X decays; (4) the OZI rule in weak decays; (5) Vector dominance (Wπ,ρ,a1,Ds,DsW \to \pi, \rho, a_1, D_s, D^*_s ) in weak decays (6) Puzzles in doubly-cabibbo-suppressed charm decays.(7) Problems in obtaining Λ\Lambda spin structure from polarization measurements of produced Λ\Lambda's.Comment: 5 page

    History and new ideas for exotic particles

    Full text link
    Basic 1966 physics of Sakharov, Zeldovich and Nambu updated by QCD with constituent-quark quasiparticles having effective masses fits all masses and magnetic moments of ground state meson and baryons having no more than one strange or heavy quark Flavor antisymmetry explains absence of low-lying exotics and suggests diquark-triquark model and two-state model for Θ+\Theta^+ pentaquark. Variational approach gives mass bounds for other pentaquarks.Comment: 15 pages, PNTA04 Conference at SPring-8, Japa
    corecore