Search

We report the results of a search for absorption of 42-cm radiation in neutral galactic hydrogen. One explanation of a positive result would be the existence of a type of anomalous proton whose magnetic moment arises from a distribution of magnetic charge rather than from a distribution of circulating currents. No absorption of 42-cm radiation was seen; this implies an upper limit of 2.3 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$ for the abundance of this type of anomalous proton relative to protons which radiate at 21 cm. The observed absence of anomalous protons also implies an absence of primordial anomalous protons since they could not have been swept up by heavier elements during cosmic nucleosynthesis. The observation is sensitive only to anomalous protons with exactly the same value for their magnetic moment that conventional ones have.

In the MIT bag model, the M1-transitions of low lying hadrons are investigated. The following calculations are performed: 32 hadron masses are recomputed with a choice of bag parameters designed to give the correct values for the proton magnetic moment, ..mu../sub p/, and several masses, M/sub rho/ M/sub ..omega../ M/sub ..delta../ M/sub ..cap omega../, and M/sub D/; (2) eta, eta', eta/sub c/ mixing is computed in an untrustworthy approximation; and the widths for 38 M1-transitions are computed.

We calculate, for a number of cases, the cosmic temperature at which primordial quarks condense into baryons, within a field theory of partially confined quarks that enjoys temporary asymptotic freedom. We assume that the mass of a quark in a dense quark-antiquark medium is a monotonic function of the medium---that is, we assume the validity of the so-called "Archimedes effect." We show that, within such models, unbound-quark lifetimes are larger than the age of the universe at the time of the transition and that

We show (1) that the two-body cross section for monopole-antimonopole annihilation is smaller when photon discreteness effects are included than previously believed; (2) that the three-body annihilation process should dominate the two-body process; but (3) that, even when monopole clumping and monopole dilution by entropy production is taken into account, these processes do not appear to provide a solution to the cosmological monopole problem in that either the monopoles do not annihilate or they annihilate so late that an unacceptable amount of entropy is produced.

This work is a prelude to a phase-shift analysis of $\ensuremath{\pi}N\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}N$ which we are presently performing. We here review the partial-wave isobar formalism for the above process and introduce the notation being used in our analysis. We compute the partial-wave projections of the one-pion-exchange diagrams because we hope to use the high-partial-wave contributions of these diagrams, which are not modified by the interactions, to remove phase ambiguities in the partial waves being varied. A study of the low partial waves, even though they violate unitarity badly, gives modest insights into the results of previous partial-wave analyses.

We use the effective chiral-symmetry Lagrangian to compute the amplitude for $\ensuremath{\nu}(\overline{\ensuremath{\nu}})+N\ensuremath{\rightarrow}\ensuremath{\nu}(\overline{\ensuremath{\nu}})+N+\ensuremath{\pi}+\ensuremath{\pi}$ and the integral of the differential cross sections for these processes over the kinematic region for which the Lagrangian tree approximation should be dominant. We estimate the effects of final-state interactions by comparing experimental $\ensuremath{\pi}N\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}N$ results with effective-Lagrangian predictions. Sensitivities to the neutral-current parameters $\ensuremath{\alpha}$, $\ensuremath{\beta}$, and $\ensuremath{\gamma}$ and to the chiral-symmetry-breaking parameter $\ensuremath{\xi}$ are considered.

We extend previous work on weak-neutral-current dipion production to production by the charged current. We integrate cross sections for ..nu..(nu-bar)+N..--> mu../sup -/(..mu../sup +/)+N+..pi..+..pi.. over the kinematic region for which the effective broken-chiral-symmetry Lagrangian tree approximation should be dominant. We estimate the effects of final-state interactions by comparing experimental ..pi..N..--> pi pi..N results with effective-Lagrangian predictions for that process. We compare our results with a small amount of preliminary data from a charged-current experiment.

Mass differences between members of isotopic-spin multiplets of hadrons are calculated in the MIT bag model. All low-mass SU(4) multiplets of spin 0, 1/2, 1, and 3/2 particles are considered. Both Coulomb and magnetic contributions to mass differences are evaluated without the assumption of SU(6)-degenerate intermediate states. The mass difference between the "up" and the "down" quarks inside the bag is not (necessarily) taken to be a constant; we propose a parameterization for it that works well for its contribution to known hadron electromagnetic mass differences. Based on the parametrization we present a class of sum rules for charmed-particle electromagnetic mass differences.

A renormalizable model in which weak interactions are mediated by spin-0 exchange rather than by spin-1 exchange is studied. The lowest-order diagrams for ..mu.. and ..beta.. decay are box diagrams. Neutrino cross sections off leptons and hadrons are calculated for the effective charged and neutral currents of the model. Weak corrections to e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/ and higher-order contributions to ..mu.. decay are also calculated. Neutral-current effects are predicted to be small for neutrinos on lepton targets and large for e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/; their strength is fixed by ..nu..--hadron scattering. In particular, there is a sizeable suppression of ..nu../sub ..mu../e scattering and a large enhancement of the asymmetry in e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/. The only troublesome prediction is a parameter-free value of 1 for the ratio sigma (..nu../sub ..mu../ + N ..-->.. ..nu../sub ..mu../ + X) / sigma (anti ..nu../sub ..mu../ + N ..-->.. anti ..nu../sub ..mu../ + X). On the whole, however, the model provides a sensible, renormalizable alternative to the gauge theories. (AIP)

We construct a threshold K matrix for the dominant PS11(epsilonN) contribution to ..pi../sup -/p ..-->.. ..pi../sup +/..pi../sup -/n that agrees with (1) the result of partial-wave isobar-model analyses above 1300 MeV, (2) the results of a single-arm-spectrometer experiment below 1300 MeV, and (3) the predictions of the effective Lagrangian at threshold. We find that the chiral-symmetry-breaking parameter xi is -0.2 +- 0.3, and that by only 10 MeV above threshold, isobar production accounts for roughly one-third of the total cross section.

The renormalizable perturbation expansion for the scattering of electrons and massive photons is studied, as a theorist's experiment, to test conspiracy theory for Regge trajectories. For convenience, all particles are assigned the same mass. It is shown that a nontrivial evasive solution is allowed kinematically, but that the electron trajectory does not choose it. Rather, at least to lowest order, there are three sequences of daughter trajectories, whose values differ by integers at $s=0$, and which all conspire in a complicated way with the electron to satisfy the kinematic constraints. This picture is greatly simplified using the $O(4)$ expansion of Freedman and Wang. There are only a small number of Lorentz poles. We reformulate the problem in this language and discuss some of the properties of these poles. The electron Lorentz pole factors and implies $M=\frac{1}{2}$.

We derive formulas giving the bilocal form factors, which appear in the matrix element of light-cone commutators, as Fourier transforms of scaling limits of electron scattering structure functions. We deal with the case of nonforward, spin-dependent, virtual Compton scattering. By taking the local limit of an appropriate bilocal form factor we find a new sum rule for the induced pseudoscalar coupling constant of nuclear beta decay.

The binding energy, size, and shape of finite nuclei are studied using a method which tests the "local uniformity" assumption. This assumption implies that the properties of finits nuclei ran be obtained from those of infinite nuclear matter. The energy is computed using as a trial wave function an amplitude- and frequency-modulated plane wave; this permits the use of nuclear- matter results in a straightforward manner. The calculation gives a binding energy which is too low, a radius which is too small, and a nuclear surface which is too diffuse. Several possible corrections to this result are examined. (auth)

By means of the $\frac{N}{D}$ equations, analytically continued in complex angular momentum, we consider the details of the mechanism by which cuts in the angular-momentum plane eliminate Gribov-Pomeranchuk singularities. The implications of the two-body unitarity requirement are investigated. A fixed $l$-plane pole in the signatured partial-wave amplitude is shown to exist where the first Gribov-Pomeranchuk singularity would be expected in the absence of cuts. It is also shown in this case that moving (Regge) poles are not asymptotic to the position of the fixed pole.

Assuming that Regge poles control high-energy scattering at small momentum transfers, a dynamical prediction is made for the magnitude of the total $\ensuremath{\pi}\ensuremath{\pi}$ cross section and an estimate given for the corresponding width of the forward diffraction peak, starting from a knowledge of the $\ensuremath{\rho}$ and ${f}^{0}$ masses and the lifetime of the $\ensuremath{\rho}$. The results are in satisfactory agreement with numbers inferred from high-energy $\ensuremath{\pi}N$ and $\mathrm{NN}$ scattering through the factorization theorem for residues.

We consider again an SU(2) x SU(2) x U(1) gauge theory in which the left-handed leptons (e,..nu../sub e/, ..mu.., ..nu../sub ..mu../) are in a quartet representation. The model is motivated by requiring duality in its Regge region. Here we check that the energy of the Regge region is high but not absurdly so, so that the slopes of the trajectories are not so small as to make the Regge-recurrence region forever inaccessible. We also revise our prediction for ..nu../sub e/e elastic scattering. (AIP)

Both the tractability and the reliability of the Reggeized strip approximation are increased by normalizing the long-range part of the potential at zero energy. We make the decomposition $V(t, s)=V(t, 0)+{V}^{R}(t, s)$, where $s$ is the energy squared and $t$ is the negative square of momentum transfer, and then calculate the first part $V(t, 0)$ from a low-$t$ partial-wave expansion in the $t$ reaction. The other part, ${V}^{R}(t, s)$, which vanishes at $s=0$ but which dominates at large $s$, continues to be calculated by the method of Chew and Jones from the leading crossed-reaction Regge trajectories. The normalization eliminates from the bootstrap calculation the need for accurate treatment of secondary trajectories that fail to reach $J=0$; normalization, in fact, amounts to a sum over all poles, and is useful because poles that remain in the left half of the $J$ plane may have an important influence on the low-energy potential while being negligible at higher energies.

The hypotheses of Khuri's theorem, which imply that asymptotes of Regge trajectories cannot be infinite, are studied. We show that the residue function $\ensuremath{\beta}(s)$ is expected to have an essential singularity at infinity and that $\ensuremath{\alpha}(s)$ may well have complex branchpoints, making Khuri's theorem consistent with infinite asymptotes.

We consider cosmological models in which the mass of the Universe is dominated by unstable weakly interacting particles (X-italic) with lifetime on the order of the age of the Universe. In our picture the mass of galaxies and clusters is dominated by undecayed X-italic particles while the Universe is closed in the large by their relativistic decay products. Quantitative results are given based on Turner's equations for evolution in the presence of dominant unstable particles. Several possibilities for the X-italic particle are considered. Lifetimes are calculated within these scenarios and shown to be close to those required.

The changes in primordial nucleosynthesis resulting from small corrections to rates for weak processes that connect neutrons and protons are discussed. The weak rates are corrected by improved treatment of Coulomb and radiative corrections, and by inclusion of plasma effects. The calculations lead to a systematic decrease in the predicted 4He abundance of about ΔY= 0.0025. The relative changes in other primordial abundances are also 1−2%.

crease the likelihood of SIMPs binding to heavy nuclei [14]. (ii) Gold samples with reasonably well-known long exposure times to cosmic rays are easier to find than would be the case for other elements, since gold is relatively unreactive. (iii) Gold and iron readily form negative ions, which the AMS at PRIME Lab requires in the sample injection stage. To maximize the possibility of detecting SIMPs, we looked for samples with exposure times to sources (and, hence, to SIMPs) which were both long and reasonably well known. Since likely sources of SIMPs are cosmic rays or a component of dark matter, we obtained several geological samples that were recovered from within 15 cm of the surface in regions which were relatively inactive geologically. In such regions, erosion rates can be reliably used to estimate the exposure time of each sample to these sources. A summary of the samples we studied is given in Table I, where we present the estimated exposure times of each of the geological samples assuming a SIMP penetration depth of 1 m. (Other assumed penetration depth exposure times are given in Ref. [15].) The samples denoted by Laverton and Nullagine were obtained from the Leonora District in Australia, and the Arizona sample was obtained from the Mineral Park District. The remaining samples were recovered during placer mining from Golden Valley/McDowell City and Black Run Creek, North Carolina. We also obtained three samples that came from environments which were very different from those of the geological samples, and, hence, they expand the discovery opportunity for SIMPs. The first was gold from the NASA Long Duration Exposure Facility (LDEF) satellite which was placed into a nearly circular orbit, at an altitude of 500 km, for 69 months from 1984 to 1990. During its 32 422 Earth orbits, LDEF experienced one-half a solar cycle, as it was deployed during a solar minimum and retrieved at a solar maximum. (For more details regarding the origin of these samples and the original LDEF experiment, see Horz et al. [16] and Ref. [15].)

For massive neutrinos that can decay by emission of a familon ($f$), a flavor-changing axion, the upper bound on the cosmic energy density of the decay products yields (1) an upper bound on the familon decay constant, and consequently (2) a lower bound on other $f$ emission rates. By comparing the $K\ensuremath{\rightarrow}\ensuremath{\pi}f$ lower bound with the experimental upper bound, we rule out neutrinos that decay by familon emission and have masses between 5 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$ and 0.1 MeV.

There is a possibility that a magnetic monopole has been observed by Cabrera1. The monopole density implied by the observation appears to violate bounds on the density of such particles derived from the total mass density of the Universe and from the existence of galactic magnetic fields. We show here that the observation is not inconsistent with these bounds if the monopoles and antimonopoles are bound into positronium like states with principal quantum n high enough so that the Earth's magnetic field will break them apart, but small enough so that the weaker galactic magnetic field will not. We determine a range of values for n and show that lifetimes for such bound states are longer than the current age of the Universe.

An interpretation of the meson ( kappa ), which is a 730-Mev K pi resonandce, is proposed. A scheme, based on the 1/sup -/ spin and parity assignment for the meson ( kappa ), in which all the vector resonances are interpreted as forming one multiple corresponding to the adjoint representation of SU(4) is considered. (C.E.S.)

We consider the cosmological consequences of the existence of massive, neutral, weakly interacting leptons (v/sub H/). Bounds are calculated on the v/sub H/ mass, lifetime, and allowed interaction strength by assuming minimal modification of the standard big-bang model. Our chief conclusions are :(1) The v/sub H/ may be stable if its mass is greater than a few GeV. (2) For intermediate masses, for which the v/sub H/ must be unstable, if its principal decay mode creates photons, masses less than 10/sup -/2 MeV are ruled out and its lifetime must be less than 1 year. (3) If the v/sub H/ decays exclusively into neutrinos, it may have a considerably longer lifetime and give rise to a present-day enerfy density sufficiently high to make the universe radiation-dominated and closed.

We calculate, for an open universe, the densities of radiation and matter at large times if the proton has a lifetime tau/sub p/ of about 10/sup 30/ years; we consider the contributions to these densities from the decay of matter in both clumps and interstellar gas. For times t>tau/sub p/, the energy density of the universe, for k

The possibility is considered that a spherical distribution of dark matter (DM), matter not visible with current instruments, is trapped in the sun's gravitational field. Bounds are placed from the motion of Uranus and Neptune, on the amount of DM that could be so trapped within the radius of those planets' orbits, as follows: from the Voyager 2, Uranus-flyby data new, more accurate ephemeris values are generated. Trapped DM mass is bounded by noting that such a distribution would increase the effective mass of the sun as seen by the outer planets and by using the new ephemeris values to bound such an increase.