Showing papers on "Meson published in 1972"

Photon-hadron Interactions

Abstract: * Editors Foreword Richard P. Feynman * 15 General Theoretical Background * 68 Low Energy Photon Reactions * 810 Quark Model of Resonances * 1112 Pseudoscalar Meson Photoproduction, High Energy * 1314 t-Channel Exchange Phenomena * 1421 Vector Mesons and Vector Meson Dominance Hypothesis * 2224 Electromagnetic Form Factors * 2526 Electron-Proton Scattering. Deep Inelastic Region * 2633 Parton Model * 3435 Tests of the Parton Model * 3637 Inelastic Scattering As Properties of Operators * 38 Light Cone Algebra * 3941 Properties of Commutators in Momentum Space * 4247 Electromagnetic Self Energy * 4849 Other Two-Current Effects * 5051 Hypothesis in the Parton Model * 5254 Hadron-Hadron Collisions at Extreme Energies * 55 Final Hadronic States in Deep Inelastic Scattering * 5657 Partons as Quarks

Transcendence of the Law of Baryon-Number Conservation in Black-Hole Physics

Abstract: The following result is stated: A black hole in its final state can be endowed with no exterior scalar, vector, or spin-2 meson fields. We conclude that such a black hole is not subject to the strong interactions which are mediated by meson fields such as the $\ensuremath{\pi}$, $\ensuremath{\rho}$, and $f$, and that consequently a useful definition of baryon number cannot be given for such an object.

Centrifugal-barrier effects in resonance partial decay widths, shapes, and production amplitudes

Abstract: (1) We review the experimental status of identifiable centrifugal-barrier effects in: (i) shapes of resonances, (ii) accounting for deviations in SU(2) and SU(3) predictions for ratios between partial decay widths, and (iii) accounting for the dependence on spin of the elastic widths of resonances lying on the same Regge trajectory. (2) We present a contour plot from which the "kinematic partial width" (centrifugal-barrier penetration factor times two-body phase space) of any resonance into any decay channel may be obtained immediately, given the orbital angular momentum, semiclassical impact parameter, and an assumed strong-interaction radius. Using this technique we display, as an example, the kinematically preferred decays of the high-spin mesons on the leading meson trajectory (assumed linear). (3) We obtain an approximate lower bound on the strong-interaction radius on the basis of general considerations. (4) We show that, for high-spin resonances, it can be expected that the mass enhancements in different decay channels associated with these resonances may be shifted by a half-width or so with respect to each other, because of different centrifugal-barrier effects in the different channels. (5) We also show that production cross sections of high-spin particles on leading linear trajectories by either formation or peripheral processes will be substantially suppressed by centrifugal-barrier effects. (6) Finally, we observe that the production cross sections and decay widths of mesons on the leading trajectory of the Veneziano model can be understood almost entirely on the basis of kinematical considerations if the radius of the region in which the decay particles interact strongly grows linearly with the mass of the decaying resonance.

Nonmeasurability of the baryon number of a black-hole

Abstract: One of the most astonishing features of gravitational collapse is the presumed (( ideal perfect ion, of the final state. All theoretical evidence favors the Israel-Carter conjecture, which says that the most general final configuration of gravitational collapse is a Kerr-Newman black-hole. If this conjecture is true, then it follows that the only measurable quantum numbers of a black-hole are mass, charge and angular moment u m t h e s e three quantities being the only adjustable parameters appearing in the KerrNewman metric. Any other particularity tha t the collapsing matter had fades away. Now, baryon number, one of the key quantities of particle physics is not in the list. The validity of the Israel-Carter conjecture implies then that the baryon number of a blaek-hole is not observable and consequently, as JOHN WHEELER says (1), that the law of conservation of baryons-i f not violated--is transcended in blaek-hole physics. However, as pointed out by BEKENSTEIN (2), the proofs of increasing generality of the * uniqueness of a black hole ,, given by CARTER (3), HAWKING (4), ISIr (5) and WALD (3), have not explicitly taken into account the possible effect of strong interactions which arc precisely the characteristic interaction of the baryons and which are per excellence the ~ measuring tools , for baryon number. An important step in this direction has been taken by BEKENSTEIN (3) himself who has been able to show tha t no classical meson fields, which meet some regularity conditions, can exist outside of a black-hole. Although this result probably implies tha t a black-hole cannot have any interactions mediated by mesons, even when the quantum nature of the fields is taken into account, an approach dealing with a quantum meson field from the very beginning would help to clarify the matter. Such a t reatment is given below.

Relativistic Self-Consistent Meson Field Theory of Spherical Nuclei

Abstract: A relativistic self-consistent theory is used in conjunction with meson field potentials having the form of the generalized one-boson-exchange potentials (GOBEP) to construct a relativistic self-consistent meson field theory of nuclear structure. A simple GOBEP model with qualitative features of successful $N\ensuremath{-}N$ models, e.g., approximate cancellation of static terms arising from generalized (or regularized) scalar- and vector-meson fields, is used to calculate ground-state properties of the doubly-magic spherical nuclei $^{16}\mathrm{O}$, $^{40}\mathrm{Ca}$, $^{90}\mathrm{Zr}$, and $^{208}\mathrm{Pb}$, and one superheavy nucleus $^{298}114$. Good agreement is obtained between theoretical and experimental total binding energies and radial charge distributions. The isotopic shift in charge distributions between the isotopes $^{40}\mathrm{Ca}$ and $^{48}\mathrm{Ca}$ and the single-particle eigenvalues agree quite well with the experimental numbers. The absence of explicit correlation corrections, the relationship of this model to earlier meson-theoretic descriptions, and physical interpretation in terms of nucleon form factors and relativistic interactions are discussed.

Nonelastic interactions of nucleons and pi mesons with complex nuclei at energies below 3 GeV.

Abstract: Calculation of nonelastic interactions corresponding to continuum-state transitions using the intranuclear-cascade evaporation approach. Spallation yields, energy- and angle-dependent spectra, particle multiplicities, and nonelastic cross sections are calculated for incident nucleons and pi mesons with energies below 3 GeV on complex nuclei. Comparisons with experimental data are made, and, in general, the agreement is good. Discrepancies in these comparisons are discussed with respect to the deficiencies in the model.

Primary cosmic γrays above 1012 eV

Abstract: An analysis is made of the interactions of very energetic cosmic ray primaries with the universal black body radiation in extragalactic space. The gamma rays from the initial pi 0 mesons produce electron pairs in collisions with further black body photons and a gamma -e cascade builds up through this interaction and the inverse Compton interaction. Results are given for the expected gamma -ray spectrum at the earth for a variety of assumptions about the magnitude of the primary spectrum and other parameters and comparison is made with upper limits to the gamma -ray intensity from experimental data. One conclusion that arises immediately is that if the higher of the two primary proton energy spectra is correct then the extragalactic infrared energy density must be less than about 2 eV cm-3. In general the predicted gamma to proton ratios are highest in the region of 3*1019 eV. They are mostly below present detection limits but should be detectable with the improved extensive air shower arrays at present being constructed.

Scaling properties and the bound state nature of the physical nucleon

Abstract: The scaling property in deep-inelastic electron scattering is established by regarding the physical nucleon as a bound state of a bare nucleon and a bare meson (or a few bare mesons). This bound-state formulation provides a fully relativistic generalization of the "parton" model that is no longer restricted to infinite-momentum frames. It also connects the scaling property in inelastic processes with the rapid decrease of the electromagnetic form factors in elastic scattering. Rigorous statements are derived for specific bound-state solutions of the Bethe-Salpeter equation with the ladder approximation. An Adler sum rule is derived and crossing properties are discussed. A general phenomenological approach is developed which is relativistically covariant and gauge-invariant, and which allows one to correlate directly the observed structure functions and form factors with the appropriate bound-state wave function. If all constituents in the bound state are assumed to be of masses $\ensuremath{\lesssim}1$ GeV, the model gives a qualitative understanding as to why the scaling property is experimentally observed at relatively moderate energies.

Flux Quantization and Particle Physics

Abstract: Quantized flux has provided an interesting model for muons and for electrons: One closed flux loop of the form of a magnetic dipole field line is assumed to adopt alternative forms which are superposed with complex probability amplitudes to define the magnetic field of a source lepton. The spinning of that loop with an angular velocity equal to the Zitterbewegung frequency $\frac{2m{c}^{2}}{\ensuremath{\hbar}}$ implies an electric Coulomb field, (negative) positive, depending on (anti) parallelism of magnetic moment and spin. The model implies $\mathrm{CP}$ invariance. A quark may be represented by a quantized flux loop if interlinked with another loop in the case of a meson, with two other loops in the case of a baryon. Because of the link, their spinning is very different from that of a single loop (lepton). The concept of a single quark does not exist accordingly, and it is seen that a baryon with a symmetric spin-isospin function in the SU(2) \ifmmode\times\else\texttimes\fi{} SU(3) quark representation might not violate the Pauli principle because the wave function representing the relative position of linked loops may be chosen antisymmetric. Weak interactions may be understood to occur when the flux loops involved in the interaction have to cross over themselves or over each other. Strangeness is readily interpreted in terms of the trefoil character of a $\ensuremath{\lambda}$ quark: Strangeness-violating interactions imply crossing of flux lines and are thus weak and parity-nonconserving. $\ensuremath{\Delta}S=\ensuremath{\Delta}Q$ is favored in such interactions. Intrinsic symmetries may be interpreted in terms of topology of linked loops. Sections I and II give a short r\'esum\'e of the 1971 paper.

Nova Model of Inclusive Reactions

Abstract: A model for particle production is presented in which the features recently observed in inclusive distributions can be reproduced. The calculation emphasizes the role of resonance-like objects which are diffractively produced and decay mainly through cascade emission of pions. The cross section for producing these objects which we call novas is diffractive and does not depend on energy. As a function of nova mass it rises to a low mass maximum (below 2 GeV) and falls off in a way which is controlled by Regge behavior and duality. We then construct a zero-parameter model for the inclusive distributions which also gives many predictions about exclusive reactions. Among the many features which can be obtained in terms of this picture are: the rapid approach of scaling for secondaries with relatively large center-of-mass momentum; a slower approach for soft secondaries and the pseudoscaling observed at present machine energy in certain reactions; a simple connection between the transverse-momentum distribution, the longitudinal-momentum distribution, and the average multiplicity of secondaries; charge effects which should not vanish asymptotically; and a marked difference between meson and baryon distributions. The approach to scaling is connected to the rise of the diffractive cross section as inferred from the behavior of the ${K}^{+}p$ total cross section. One also obtains an understanding for the "quark frame" results and the center-of-mass isotropy of slow secondaries.

Relativistic scalar quark model with strong binding

Abstract: The dynamics of strong binding of heavy scalar particles (quarks) are discussed with the help of the Bethe-Salpeter equation with a smooth ladder-type kernel. For this purpose, the Bethe-Salpeter amplitudes are expanded intoO4 spherical functions and the remaining « hyper-radial » equation is solved by a variational method. These calculations are considered as a model of mesons as bound states of heavy quarks. The low-lying mesons form linear trajectories with a slope of 1 (GeV)−2. The modification of the vector-meson dominance form factor by the bound-state wave functions is calculated and found to be in good agreement with experiment.

Quartet Models Based on Fundamental Particles with Fractional Charge

Abstract: Some quartet models based on fractionally charged ur-baryons are discussed in terms of a broken SU(4) symmetry. Mass spectra of baryons and mesons are calculated, which in­ clude a result of recent observation of cosmic ray jet shower. Further implications on weak interactions are also discussed. We give an explicit form for universal weak currents and new selection rules for non-leptonic and radiative decays which hold exactly in the limits of SU(3) and SU(4).