If a fourth generation of quarks ($a,v$) exists, the cross section for production of the Higgs boson in association with the $Z$ boson may be greatly enhanced. We evaluate the subprocesses $\mathrm{gg}\to \eta \left(v\overline{v}\right)\to \mathrm{ZH}$, $\mathrm{gg}\to Z^{*}\to \mathrm{ZH}$, and $q\overline{q}\to Z^{*}\to \mathrm{ZH}$ and find a substantial Higgs-boson signal in $\mathrm{pp}$ collisions at $\sqrt{s}=40\mathrm{}$ TeV.

We extend the Skyrme model to incorporate the vector mesons $\rho$ and $\omega$ in a way consistent with the non-Abelian anomalies of QCD and vector-meson dominance. The vector mesons are treated as composite gauge bosons of a hidden ${\mathrm{SU}\mathrm{}\left(2\right)\mathrm{}}_V\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ symmetry. We investigate the bulk properties of hedgehog-type Skyrme solitons in the baryon number $B=1\mathrm{}$ sector of this model.

We report a measurement of parity nonconservation in the transmission of 800-MeV longitudinally polarized protons through an unpolarized, 1-m liquid-hydrogen target. The dependence of transmission on beam properties was studied to measure and to correct for systematic errors. The measured longitudinal asymmetry in the total cross section is $A_L=[+2.4\mathrm{}\pm 1.1(\mathrm{statistical})\pm 0.1(\mathrm{systematic}\left)\right]\times {10}^{-7\mathrm{}}$.

The momentum distributions are calculated for the pions and protons which are produced in a proton-nucleus collision. We assume that in each nucleon-nucleon interaction a quark or a quark-antiquark pair is removed from the projectile. The final hadron distribution can then be expressed in terms of quark distribution functions and fragmentation functions which are both taken from lepton-nucleon collisions.

We have observed an efficient collimation of a cesium atomic beam crossing at right angles an intense laser standing wave. This new cooling scheme is mainly based on a stimulated redistribution of photons between the two counterpropagating waves by the moving atoms. By contrast with usual radiation pressure cooling, this "stimulated molasses" works for blue detuning and does not saturate at high intensity.

Working with a beam of ${}_{}{}^{174}{}_{}{}^{}\mathrm{Yb}$, we have studied the temporal development of Autler-Townes spectra following switchon of a strong, resonant, driving field. The transient fluorescence spectra observed are dramatically different from those found in the steady state. We find that either member of the Autler-Townes doublet can be eliminated by an appropriate shift in the phase of the driving field, and that the spectral peaks can display interesting temporal oscillations. The observed behavior is interpreted in terms of atomic dynamics and a polarization of the dressed atom-field states.

We have recorded the laser-excited resonance fluorescence of one to three ${\mathrm{Ba}}^{+}$ ions and observed Bohr's "quantum jumps" when an ion decayed to the metastable ${}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ state, suddenly quenching its fluorescence. Most of the jumps mark Raman-Stokes scattering from the ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ and ${}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ levels.

We detect the radiatively driven electric quadrupole transition to the metastable ${}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ state in a single, laser-cooled Hg II ion by monitoring the abrupt cessation of the fluorescence signal from the laser-excited ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ first resonance line. When the ion "jumps" back from the metastable $D$ state to the ground $S$ state, the $S\to P$ resonance fluorescence signal immediately returns. The statistical properties of the quantum jumps are investigated; for example, photon antibunching in the emission from the $D$ state is observed with 100% efficiency.

Neutral sodium-water clusters are formed in a "pickup" source, injection of a beam of Na atoms into the expansion zone of a pulsed nozzle-jet beam of water vapor seeded into an argon carrier gas. They are detected by near-uv one-photon ionization with a pulsed laser and time-of-flight mass spectroscopy. $\mathrm{Na}{\left({\mathrm{H}}_2\mathrm{O}\right)}_n$-cluster-ion signals up to $n=12\mathrm{}$ are seen, $n=4\mathrm{}$ showing a very pronounced abundance. The ionization potential of NaO${\mathrm{H}}_2$ is determined to be 4.379 ± 0.002 eV.

The cross sections and asymmetry parameters of the two $\pi -{\pi }^{*}{}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$ shakeup satellites on $\mathrm{C} 1s$ in the photoelectron spectrum of CO are found to differ significantly in the threshold region. The first satellite (due to triplet $\pi -{\pi }^{*}$ coupling) shows intensity enhancement near threshold whereas the second satellite (singlet $\pi -{\pi }^{*}$ coupling) decreases in intensity as expected for the adiabatic limit. Moreover, the data indicate that a shape resonance in the first-satellite channel is responsible for the observed effect rather than a conjugate shakeup process.

We show that if a state decays to produce a fraction $R$ of products in one of two decay channels, then one can obtain the complementary fraction, $1-R$, by exciting the character of a different state, but at the location of the first state's resonance. This structure will appear as a satellite to the second state with a branching ratio that depends only on the first state's decay interactions. Since this requires the real excitation of a state far off resonance, this process will be important only for short-lived states, which have long wings in their excitation spectra. We illustrate this effect with the $6pns$ and $6pnd$ autoionizing states of barium.

The divergence of the shear viscosity observed in classical fluids near solidification is explained on the basis of the extended mode-coupling theory using two coupled extended heat modes.

We study patterns formed by the viscous fingering instability in a porous medium. The wetting properties of the medium have a profound influence on the width of the individual fingers and consequently on the shape of the overall pattern. If the displaced fluid preferentially wets the medium, the finger width is comparable to the pore size, independent of other parameters. In contrast, if the displacing fluid preferentially wets the medium, the finger width is much larger than the pore size, and, when normalized by the square root of the permeability, is found to scale with the capillary number approximately as $N_{\mathrm{Ca}}^{-\frac{1}{2}}$.

Using renormalization-group methods and the postulated equivalence between the inertial-range structures of turbulent flows satisfying initial and boundary conditions and of flows driven by a random force, we evaluate the Kolmogorov constant (1.617) and Batchelor constant (1.161), skewness factor (0.4878), power-law exponent (1.3307) for the decay of homogeneous turbulence, turbulent Prandtl number (0.7179), and von Kármán constant (0.372). This renormalization-group technique has also been used to derive turbulent transport models.

We report the first observation of up-shifted scattered light from Raman forward scattering. Computer simulations show this scattering to be a characteristic signature of that instability. The up- and down-shifted spectra are in good agreement with the interpretation of anti-Stokes and Stokes waves, respectively. We have correlated the observations of both the up-shifted and down-shifted forward spectra with the theoretically expected superhot electrons. The experiments used the Nova laser facility to irradiate thin CH targets with 1-nsec pulses of 0.53-μm light.

The Columbia Linear Machine has been redesigned to enter the parameter regime of the collisionless, curvature-driven, trapped-particle instability. With the new machine configuration, a strong ($\frac{\tilde{n}}{N}\gtrsim 60\%$), coherent mode is observed which bears all the characteristics of this instability. These include strong localization to the mirror cell, broad radial-mode structure, and MHD-like body motion of the plasma column. Furthermore, the mode exhibits all the correct parametric dependences of increasing mode amplitude with increasing mirror ratio and rf power, and decreasing mirror-cell length.

bcc crystalline colloidal microsphere suspensions are shear melted into the metastable liquid phase. Recrystallization occurs via nucleation and growth of single crystallites at dilute sites. The nearly spherical growing crystals have rough interfaces with a time-independent interface velocity, $v$. The velocity is found to be consistent with an equation for normal growth with a limiting velocity determined by free-particle diffusion, $v_0\sim \frac{D_0}{\xi }$, where $D_0$ is the Stokes diffusion constant of independent noninteracting spheres, and $\xi$ is a length comparable to the particle spacing.

A theory of fracture in spatially varying anisotropic glass is developed to interpret electron micrographs of freeze-fractured surfaces of cholesteric samples. The expression for energy per unit area released by crack formation is $\gamma \propto {\left[\mathbf{n}·\right(1+b{\mathbf{Q}}_1\left)·\mathbf{n}\right]}^{\frac{1}{2}}$, where $Q_1$ is the traceless Landau tensor for unit order parameter and $\mathbf{n}$ is a unit vector normal to the crack surface. The two parameters of the theory are $b$, which is a function of the ratio of length to width of molecule, and a crack-precursor length. Contours closely matching those observed in the laminar cholesteric texture and in blue phase I are generated.

We report the direct measurement of the diffusion of polystyrene in porous silica by dynamic light scattering. The effective diffusion coefficient is smaller than the diffusion coefficient in bulk solution ($D_0$), and depends on the scattering wave vector $q$. At low $q$, macroscopic diffusion coefficients ($D_{\infty }$) are obtained; the ratio $\frac{D_{\infty }}{D_0}$ depends on the size of the polymer. At higher $q$, where $q^{-1\mathrm{}}$ is comparable to pore dimensions, more complicated "transitional" behavior is seen.

We propose a simple NMR technique, and the underlying theory, to evaluate, with high accuracy, four out of the five viscosity coefficients and the ratio $\frac{k_{33}}{k_{11}}$ of the bend to splay Frank elastic constants, in nematic polymers. Quantitative data on the viscosities ${\gamma }_1$, ${\alpha }_1$, ${\alpha }_2$, and ${\eta }_c$ and the ratio $\frac{k_{33}}{k_{11}}$ are given for the first time for a thermotropic nematic polymer. The material studied is poly (4,4′-dioxy-2,2′-dimethyl azoxybenzenedodecanediyl), a linear polyester usually labeled DDA9.