A theory of the tetramethyltetraselenafulvalene (TMTSF) salts and their sulfur analogs is developed. It is shown that the phase diagram is controlled by electron-electron umklapp scattering. The theory accounts for differences between the sulfur and selenium series, and the absence of Peierls transitions. Predictions of the pressure dependence of the spin-density-wave critical temperature and correlations of the dimerization of the organic stacks with critical pressures and temperatures are verified experimentally.

The density of states and the localized or extended nature of the eigenstates is investigated in one-dimensional crystals with a modulation potential incommensurate with that of the underlying lattice. Studies of the transmission coefficient $T$ and of the spatial dependence of the eigenstates show that even in one dimension it is possible to have a mobility edge. The implications of these results on experimentally measured quantities are also discussed.

The spin-orbit coupling modifies the weak localization of the conduction electrons in thin films and reverses the magnetoconductance. This is quantitatively demonstrated in Mg films covered with submonolayers of Au. The effect provides a new and direct method for measuring the spin-orbit coupling.

Random-field effects have been studied, using linear birefringence, in the random Ising antiferromagnets ${\mathrm{Fe}}_x{\mathrm{Zn}}_{1-x}{\mathrm{F}}_2$ and ${\mathrm{Mn}}_x{\mathrm{Zn}}_{1-x}{\mathrm{F}}_2$. with $0<\mathrm{}{H}_0<~20$ kOe parallel to $c$, large shifts in $T_c$ and dramatic changes in the shapes of the transition peaks were observed. These results confirm some, but not all, theoretical predictions and suggest an effective dimensionality $d\simeq 2$. No $H_0$-induced rounding was observed. This is shown to be consistent with the rounding seen in other experiments at larger values of $\frac{g{\mu }_{\mathrm{B}}{H}_0}{k{T}_c}$.

Iron meteorites contain an ordered FeNi (50%-50%) alloy. By study of the disordering process above the transition temperature $T_c\simeq 593$ K with Mössbauer spectroscopy, it is shown that the hyperfine parameters reflect the degree of order. This depends on the cooling rate of the meteorites. As the hyperfine parameters, and therefore the degree of order, vary from meteorite to meteorite, the ordered FeNi alloy contains information on the relative cooling rates of meteorites.

In the framework of stochastic quantization the stochastic process is derived for the harmonic oscillator in equilibrium with a thermal bath. This allows one to treat the quantum and thermal fluctuations within the same scheme of stochastic differential equations. As an application of the theory the quantum-classical crossover is computed in the dynamical critical exponent of the Van Hove model.

The results are reported of a search for excited muons (${\mu }^{*}$) and electrons ($e^{*}$) and for a stable charged heavy lepton by measurements of the $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$, ${\mu }^{+}{\mu }^{-}\gamma$, ${\mu }^{+}{\mu }^{-}\gamma \gamma$, and $\gamma \gamma$ final states. Excluded are large regions of the $\lambda$ (coupling constant), $M$ (mass) planes for spin-½ ${\mu }^{*}$ and $e^{*}$, and a new stable charged heavy lepton with mass < 14 GeV.

The electron asymmetry was measured in the beta decay of polarized sigma hyperons ${\Sigma }^{-}\to n{e}^{-}\overline{\nu }$ produced in the reaction $K^{-}p\to {\Sigma }^{-}{\pi }^{+}$ at the ${Y_0}^{*}\mathrm{}\left(1520\right)\mathrm{}$ resonance. Particles were tracked in a magnetic spectrometer and a large-acceptance, segmented, gas-Cherenkov-scintillation counter array identified electrons. A maximum-likelihood analysis based on 193 events yields the electron asymmetry of ${\alpha }_e=0.35\mathrm{}\pm 0.29$. The result favors a positive value for $\frac{g_1}{f_1}$ which is opposite to the Cabibbo-favored sign.

Three-dimensional Yang-Mills and gravity theories augmented by gauge-invariant mass terms are analyzed. These topologically nontrivial additions profoundly alter the particle content of the models and lead to quantization of a dimensionless mass-coupling-constant ratio. The vector field excitations become massive, with spin 1 (rather than massless with spin 0), and the mass provides an infrared cutoff. The gravitation acquires mass, mediates finite-range interactions, and has spin 2 (rather than being absent altogether); although its mass term is of third derivative order, there are no ghosts or acausalities.

Elastic scattering of $p$-shell nuclear projectiles from ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ has been examined for deviations from Rutherford scattering. Four effects can be important: atomic screening, vacuum polarization, nuclear polarizability, and a relativistic effect of dynamical origin. The presence of atomic screening, nuclear polarizability, and the relativistic effect was observed, thus constituting the first measurement of this relativistic effect using complex nuclei and the first measurement of nuclear polarizability in an external Coulomb field.

The perturbed-angular-distribution method has been used to measure the $g$ factor of the $\tau =122\mathrm{}\left(10\right)\mathrm{}$-nsec fission isomer in ${}_{}{}^{237}{}_{}{}^{}\mathrm{Pu}$. To eliminate unwanted perturbations, a special cubic nonparamagnetic alloy, ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$${\mathrm{Ir}}_2$, was heated to 950°C and used as the target. The quantities measured were $A_{22}=+0.21\mathrm{}\left(6\right)\mathrm{}$ and $g=-0.45\mathrm{}\left(3\right)\mathrm{}$. The $g$ factor is consistent with the $I=\frac{3}{2}$ ground state of the 871 ${\mathrm{½}}^{+}$ Nilsson orbital, and the fission anisotropy is consistent with $K=\frac{1}{2}$ at the second saddle point.

The most stringent test to date of the concept of isospin splitting of the giant dipole resonance in a medium-weight nucleus has been performed by a study of the ($\gamma , n_0$), ($\gamma , p_0$), and ($\gamma , \gamma$) reaction channels for ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$. The ground-state photoneutron cross section for ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$ was measured and compared with the already known ($\gamma , p_0$) reaction cross section in order to demonstrate isospin splitting. The relative strength and separation of the isospin-dependent components of the resonance were estimated from an analysis of photon scattering data.

The forward-angle differential cross sections of pion single charge exchange on ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ were measured at 70, 100, 150, 165, and 180 MeV. The cross sections rise steeply up to 150 MeV and remain almost constant between 150 and 180 MeV. Comparisons with theoretical calculations and with the free charge-exchange cross sections are presented. There is poor agreement with the data. Only phenomenological calculations can fit the resonance region. The isobaric analog excitation functions rise more steeply than the continuum single-charge-exchange cross sections.

It is suggested that the difference which presently exists between neutron-neutron effective-range parameters extracted from the reactions $\mathrm{D}({\pi }^{-},\gamma )2n$ and $\mathrm{D}(n, 2n)p$ can be explained by the same three-body force which describes ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The effects of the three-body force are different for neutron pickup and proton knockon processes in the reaction $\mathrm{D}(n, 2n)p$.

The reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}(p, {\Delta }^{++}){}_{}{}^6{}_{}{}^{}\mathrm{He}$ has been studied at 1.04 GeV for transferred momenta ranging from 0.11 to 0.35 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. An exponential decrease of the cross section is observed. A Glauber-type calculation is presented. The possibility of extracting information on ${\sigma }_{\Delta N}$ and ${\alpha }_{\Delta N}$ is discussed.

The accuracy of an $L^2$ discretization approximation as a means of incorporating effects of three-particle breakup on two-body scattering amplitudes has been tested in a soluble three-particle model. The coupled-reaction-channel Ansatz for the Schrödinger wave function was found to respond better to discretization than any of the connected-kernel, three-particle scattering formalisms.

A search has been made with the Crystal Ball Detector for axionlike particles in radiative $\frac{J}{\Psi }$ decays. An upper limit on the branching ratio $B(\frac{J}{\Psi }\to \gamma +a)<\mathrm{}1.4\mathrm{}\times {10}^{-5\mathrm{}}$ (90% C.L.) is obtained. This result holds for long-lived, noninteracting pseudoscalar or vector particles of mass less than 1 GeV. Thus, this experiment also places stringent limits on the existence of other possible light bosons such as those arising in supersymmetric theories.

The CUSB detector at the Cornell Electron Storage Ring has been used to measure $R=\frac{\sigma (e^{+}{e}^{-}\to \mathrm{hadrons})}{\sigma (e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-})}$ in the c.m. energy regions between the ${\Upsilon }^{\prime \prime }$ and the ${\Upsilon }^{\prime \prime \prime }$, and above the ${\Upsilon }^{\prime \prime \prime }$ up to $\sqrt{s}=11.6\mathrm{}$ GeV, with integrated luminosities of 5000 and 2100 ${\mathrm{nb}}^{-1\mathrm{}}$, respectively. No narrow resonances are observed, and limits on the leptonic widths are presented. The average value of $R$ increases by 0.31±0.06 across the flavor threshold.

In an exposure of the deuterium-filled 15 ft bubble chamber, $\frac{\sigma ({\nu }_{\mu }n\to {\nu }_{\mu }X)}{\sigma ({\nu }_{\mu }p\to {\nu }_{\mu }X)}$ is measured to be 1.01±0.14. The ratios of neutral-current to charged-current cross sections are 0.30±0.03, 0.22±0.03, and 0.49±0.06 for ${\mathrm{D}}_2$, $n$, and $p$ targets, respectively, which imply values ${u_L}^2=0.19\mathrm{}\pm 0.06$ and ${d_L}^2=0.13\mathrm{}\pm 0.04$ for the neutral-current chiral couplings. Evidence for both $u$- and $d$-quark jets in neutral-current reactions is observed in distributions of energy fraction of the fastest hadron of either charge from each event.

The ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}(0^{-}, 120 \mathrm{keV})\to {}_{}{}^{16}{}_{}{}^{}\mathrm{O}(0^{+},\mathrm{g}.\mathrm{s}.\mathrm{})+e^{-}+{\tilde{\nu }}_e$ beta decay rate is remeasured. The present result, ${\Lambda }_{\beta }=0.41\mathrm{}\pm 0.06$ ${\sec }^{-1\mathrm{}}$, agrees with recent realistic calculations of this rate only when pion exchange currents are included in the axial-vector time component. The impulse approximation underestimates this rate by more than a factor of 3. This result may be combined with the muon capture rate for the inverse reaction to obtain $\frac{g_P}{g_A}=10\mathrm{}\pm 2.5$.