We report evidence for the existence of a new meson, which we call the $M\left(953\right)\mathrm{}$, with mass 953 ± 2 MeV and width <10 MeV, produced in the final state $K^{-}p\to p{K}^{-}{M}^0$ at incident momenta 3.9 and $4.6\frac{\mathrm{GeV}}{c}$. These results are based primarily on a signal of 68 ± 12 events in the decay mode $M\to {\pi }^{+}{\pi }^{-}\gamma$ where the $\pi \pi$ system does not show a ${\rho }^0$ signal, in sharp distinction to the ${\rho }^0\gamma$ decay mode of the ${\eta }^{\prime }\mathrm{}\left(958\right)\mathrm{}$.

Resonances have been observed in neutral lithium vapor by absorption spectroscopy for photons in the 50- to 70-eV energy range. These resonances are due to the excitation of a $K$-shell electron, or the simultaneous excitation of a $K$-shell electron and an outer electron to final states of the type ($1s2pnl$) or ($1snl{n}^{\prime }{l}^{\prime }$). Several well-developed series have been observed as well as resonances where energy position and intensity are perturbed by neighboring configurations.

Close coupling calculations of the optically allowed states in the 60-70 eV range above the ground state of atomic lithium have been performed. An interpretation of the resonant structure in this region is given based upon these calculations and recent experimental evidence.

It is suggested that the property of nonclassical rotational inertia possessed by superfluid liquid helium may be shared by some solids. In particular, nonclassical rotational inertia very probably occurs if the solid is Bose-condensed as recently proposed by Chester. Anomalous macroscopic effects are then predicted. However, the associated superfluid fraction is shown to be very small (probably $\lesssim {10}^{-4\mathrm{}}$) even at $T=0\mathrm{}$, so that these effects could well have been missed. Direct tests are proposed.

We have used Raman scattering to study roton pairs in liquid helium at 1.2°K. We find that the energy required to create two rotons is less than twice the energy of a single roton. This result can be explained by the existence of a two-roton bound state. Comparison of our spectra with theoretical calculations gives a binding energy of (0.37 ± 0.10)°K and shows that the pair is in a $D$ state ($L=2\mathrm{}$) of angular momentum.

We have measured the temperature dependence of the intensity and spectrum of light scattered by fluctuations in the nematic phase of $p$-methoxy-benzylidene $p-n$-butylaniline. Our measurements are interpreted using two phenomenological theories of nematic liquid crystals.

Experimental results are reported on the dynamic stabilization of drift waves in a $Q$-machine plasma by means of ac electric fields parallel to the magnetic field. Appreciable stabilization has been obtained both at ac frequencies around the wave frequency and at very high ac frequencies.

Small-angle x-ray scattering techniques have been used to investigate the temperature dependence of the isothermal compressibility of argon at its critical density for temperatures in the critical region and above the critical temperature. The coexistence curve and the long-range correlation length have also been studied. Within experimental uncertainty the results are in agreement with the scaling laws.

Observations of marginally unstable resistive drift waves in a hydrogen plasma immersed in the sheared magnetic field of the Princeton spherator are reported. A theoretical treatment based on the nonlocal normal mode is proposed, which predicts the wave parameters of the most unstable mode, and provides a new stability criterion. The experimental wave parameters and observed stabilization of the resistive drift waves are found to agree well with the predicted values.

The dc conductivity in a turbulent discharge-tube plasma has been measured as a function of dc electric field over the range 0.06 to 300 V/cm. Below approximately 60 V/cm the conductivity can be interpreted quantitatively in terms of the ion-acoustic wave instability. Above 60 V/cm the conductivity is approximately constant and about an order of magnitude lower than that calculated by Buneman for the two-stream instability.

The interior of a plasma column is subjected to shear of arbitrary magnitude in the $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ rotation. The resultant Kelvin-Helmholtz instability undergoes an evolution in mode structure as the radial electric field is increased, and is suppressed when the Doppler-shifted wave frequency equals 0.5 to 0.65 times the ion-cyclotron frequency. Cyclotron waves appear concomitant with this suppression; these have properties in agreement with linear fluid theory.

Electromagnetic waves are excited in Al-Pb superconducting tunnel junctions by compressional 9.3-GHz acoustic waves when the acoustic wave front makes a small angle with the plane of the tunnel junction. The electromagnetic waves are induced by the electrostatic field in the superconducting Al film which is due to the compressional strain gradient in the Al. This result provides experimental confirmation of the theories of Dessler et al. and Herring developed for the case of gravitation-induced strains.

The chemisorption energy of an atom in the $5d$ series on a tungsten substrate is calculated on the basis of a two-center Hubbard model, for which the ground-state energy may be obtained exactly. The experimental data can be fitted with a choice of parameters consistent with independent estimates.

The authors have successfully exploited the Tomasch effect in quasiparticle tunneling from thick, superconducting, single-crystal Pb films to measure Fermi velocities in three high-symmetry directions. Multiple gaps were observed in all of these directions which agree with those reported earlier in bulk single-crystal studies, indicating that these films behave in a fashion similar to bulk Pb.

The 30°-30° proton-proton bremsstrahlung cross section and its noncoplanar dependence were measured at 64.4 MeV. The measured noncoplanar dependence agrees with theoretical calculations, but the coplanar cross section, 2.32 ± 0.20 μb/${\mathrm{sr}}^2$, is significantly below the predicted values.

We show that the ground-state energy for a Hamiltonian $H_0+\int g\left(x\right):{\varphi }^4\mathrm{}\left(x\right):dx$ ($g\in L^1\cap L^2$; $g>~0$; $H_0=\mathrm{free}$ Hamiltonian for Bose particle of mass $m$ in space-time of two dimensions) may be determined from the Feynman perturbation series by the method of Borel summability. This demonstrates that summability methods can be applicable to divergent series in systems with a continuous infinity of degrees of freedom.

We study high-energy elastic and inelastic processes in a ${\varphi }^3$ theory based on the $s$-channel iterations of $t$-channel ladder diagrams. The main results are the following: (a) The total cross section goes to zero, a constant, or $\sim {\left(\ln s\right)}^2$ for the coupling constant being smaller than, equal to, or larger than a critical value. (b) Inelastic differential cross sections are computed and the $s$-channel unitarity is explicitly verified. (c) One-particle spectrum, multiplicity, number distribution, etc. are presented. The implications of these results to hadron physics are discussed.

We study the asymptotic behavior of two-tower exchange with linked ends in ${\varphi }^3$ theory using Feynman parameter techniques. We present a new result for the asymptotic behavior of the Mandelstam graph and note that only this graph contributes for the two-tower case. We generalize the above to the $N$-tower case and find the eikonal form.

A simple way of introducing second-class currents has been suggested by naturally incorporating a tensor density in the theory. A possible explanation for large $\xi$ and ${\lambda }_{+}$ parameters in $K_{l3\mathrm{}}$ decays is also proposed.

The concepts of irreducible mass and of reversible and irreversible transformations in black holes are introduced, leading to the formula $E^2=m_{\mathrm{ir}}^{}{}_{}{}^2+\left(\frac{L^2}{4m_{\mathrm{ir}}^{}{}_{}{}^2}\right)+p^2$ for a black hole of linear momentum $p$ and angular momentum $L$.