2,696 research outputs found
Theories of Non-Experiments in Coherent Decays of Neutral Mesons
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; 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
Branching ratios observed for and B decays to final states
are comparable to those for corresponding decays to
and and much larger than those for all other
decays. Implications are discussed of a "vector-dominance model" in which a
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
decays into neutral final states , and . .
Branching ratios of are predicted for the as yet unobserved
presence of the charmed-strange axial vector in B decays.Comment: 14 page
What is coherent in neutrino oscillations
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
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
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 decays; (3) anomalously
enhanced and suppressed decays; (4) the OZI rule in weak
decays; (5) Vector dominance () in weak
decays (6) Puzzles in doubly-cabibbo-suppressed charm decays.(7) Problems in
obtaining spin structure from polarization measurements of produced
's.Comment: 5 page
History and new ideas for exotic particles
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
pentaquark. Variational approach gives mass bounds for other pentaquarks.Comment: 15 pages, PNTA04 Conference at SPring-8, Japa
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