Evidence for a narrow width boson of mass 2.95 GeV

In a search for resonances coupled to the $\text{p}$pπ^? system, we have studied π^?p interactions at 16 GeV/c giving a forward antiproton, using the Omega spectrometer at CERN. In the final states involving a $\text{p}$, p and π^? we observe a 5.6 (6.3) standard deviation enhancement in the $\text{p}$pπ^? mass spectrum at (2.95 ± 0.01) GeV with a width consistent with the resolution (σ = 15 MeV). The production cross section × branching ratio is estimated to be of the order 1 μb. The data are consistent with a resonance decaying partly via intermediate $\text{p}$p final states.     

The interaction of nucleons with antinucleons. III. Photon and pion emission from bound states

We calculate widths and branching ratios for the emission of γ rays or pions from a bound state of the nucleon-antinucleon ($\text{N}\text{N}$) system, leading to another $\text{N}\text{N}$ bound state. We use a realistic potential model to describe the medium- and long-range parts of the $\text{N}\text{N}$ interaction, and parametrize the short-range behavior. The general features of γ and π transitions, based on the selection rules, are emphasized. We illustrate these features with typical results for several choices of the short-range cutoff. The observation of pions is a necessary supplement to the γ-ray experiments, in order to significantly constrain the possible quantum number assignments of final states. We investigate transitions between quasiatomic (QA) and more deeply bound quasinuclear (QN) states, and also QN to QN γ or π emission. The former may have been seen in experiments involving the $\text{p}\text{p}$ atom, while the latter are in some optimum cases accessible in $\text{p}\text{d}$ spectator experiments, although there is no evidence for these QN to QN transitions as yet. The role of isospin mixing in QA states is discussed, as well as the importance of maintaining orthogonality of the QA and QN wave functions.     

Energy levels in 142Nd

The excited states of ¹⁴²Nd were studied by means of the decay of 40 sec ¹⁴²Pm and the ¹⁴²Nd(p, p') reaction via isobaric analog resonances. Approximately sixty levels of ¹⁴²Nd were observed below 5.3 MeV excitation, including several neutron particle-hole states excited strongly in (p, p') at f_{$\text{7}\text{2}$}, p_{$\text{3}\text{2}$}, p_{$\text{1}\text{2}$} and f_{$\text{5}\text{2}$} analog resonances. We have collected together all known energy levels in ¹⁴²Nd and have proposed J^π assignments for 22 excited states. We have also compared the experimental level spectrum (positive-parity states only) with a calculated one based on the shell model.     

CP violation and Fritzsch mass matrices

We discuss a form for the quark mass matrices which produces maximal weak but no string CP violation. The quark mass matrices are of the Fritzsch type, with all phases equal to multiples of $\text{1}\text{2}\text{π}$. We show that these matrices can be produced in an SO(10) model with CP violated spontaneously at the GUT scale. The model successfully predicts the entire K-M matrix. Radiative corrections to $\text{θ}$, however, are several orders of magnitude too large in the model, and $\text{θ}$ is naturally of O(10^?5).     

Coulomb excitation of 115Sn

Coulomb excitation of the nucleus ¹¹⁵Sn was studied with beams of ⁴He and ¹⁶O. Level energies, spins, mean-lives and B(E2) and B(M1) transition probabilities were obtained. Spin $\text{3}\text{2}$⁺ states were observed at 497.35 and 1280.08 keV and spin $\text{5}\text{2}$⁺ states were observed at 986.54 and 1416.78 keV. A state of 612.79 keV was observed to be indirectly excited by decay of the Coulomb excited states. Eleven B(E2) values and nine B(M1) values were obtained for the transitions between the low-lying states. In contrast to previous particle transfer results which suggested a clear distinction between shell-model and collective $\text{3}\text{2}$⁺ and $\text{5}\text{2}$⁺ states, our results suggest the collective strength is shared by the two $\text{3}\text{2}$⁺ and two $\text{5}\text{2}$⁺ states.     

Implications of the τ and b spins for theories of quarks and leptons

We argue that the present evidence that the spin of the τ is $\text{1}\text{2}$ is circumstantial, and that a spin of $\text{3}\text{2}$ is not excluded. If the τ spin were $\text{3}\text{2}$, it would have important implications for the idea that leptons and quarks were composite states, perhaps allowing an explanation of the existence of three generations. Supergravity ideas could also be affected. Similar ideas suggest the b-quark could have spin-$\text{3}\text{2}$; we give several ways to test this.     

Search for narrow baryonium states near the NN threshold

The reactions $\text{p}\text{p}\text{→π}{}^{\mathrm{?}}\text{X}\text{and}\text{p}\text{d}\text{→}\text{pX}$ earch for narrow baryonium states in the mass region between 1.6 and 2.0 GeV/c². No such state has been observed. In the first reaction the upper limit for the production of narrow baryonium states is 8μb/sr for a 3 standard deviation signal with 4 MeV/c² width. In the second reaction this limit is 10 μb/sr. The second reaction is rather insensitive for observation of baryonium states as it is dominated by quasi-free contributions.     

Isotope effects and novel level crossings observed by ODMR in 6H SiC(Ti)

Optical detection of magnetic resonance (ODMR) and magnetic-field-induced level crossings reveal two distinct S=1 excited states in the luminescence of 6H SiC containing titanium. Resolved structure on the lines is interpreted as an unusally large isotope effect, the zero field splitting D changing $\text{～}\text{1}\text{2}\text{\%}$ per unit atomic mass change for the five naturally occuring titanium isotopes. The sharp level crossings result from cross relaxation between one of these excited triplet states and other spin systems.     

Proton 1h112 excitations in odd-mass N = 82 nuclei

The structure of negative-parity states in odd-mass N= 82 isotones (135 ≦ A ≦ 145) is investigated in the framework of a model which is based on coupling one $\text{1h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ proton to π = + 1 states of the appropriate doubly-even isotonic core. It is shown that an effective model-space truncation can be achieved if only core states in the vicinity of the yrast line are taken into account. These have been selected from the several hundreds or even thousands of states obtained from shell-model calculations, where the $\text{1g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$, $\text{2d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$, $\text{2d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{3s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ single- are assumed to be occupied. Spectroscopic data are calculated and predictions on the structure of low-lying π = ? 1 states are discussed and compared as far as possible to experimental findings. Thereby, the particle-core coupling approach is shown to be capable of describing essential properties of negative-parity levels in the N = 82 nuclei considered.     

Magnetic moments of the 12+ isomeric states in 194, 196, 198Pb

The g-factor of the 12⁺ isomeric state in lead isotopes with A = 194, 196, 198 was measured using the time-differential perturbed angular distribution method (TDPAD). The values obtained are respectively g(194) = ?0.158(6); g(196) = ?0.157(7); g(198) = ?0.144(11). A more precise determination of the 12⁺ level half-life is also made. The g-factprs of these nuclear states, which are described with v(i_{$\text{13}\text{2}$})^?2 as the main configuration, are surprisingly constant over a large mass range (between A = 206 and 194). A core polarization analysis explains this trend: the polarization induced on neutrons in i_{$\text{13}\text{2}$} orbit decreases with the mass number A (blocking effect), but a compensation is provided by the other spin-orbit partners f_{$\text{7}\text{2}$}-f_{$\text{5}\text{2}$} and P_{$\text{3}\text{2}$}-P_{$\text{1}\text{2}$}.     

Finite size scaling and low mass glueballs

We propose finite lattice effects as a probe of the glueball mass spectrum, and give an analysis of the recent SU(2) Monte Carlo data of Brower, Nauenberg and Schalk in terms of a gas of free glueballs. For L⁴ lattices with L = 4, 5, 6 fits are made to ξ(m = 1/aξ) which indicate a rather large effective number of degrees of freedom (i.e. statistical degeneracy where a spin J counts as 2J + 1) from 5 to 15 states. As the degeneracy is increased, the central glueball mass increases from $\text{m = (1.3±0.2)}\text{κ}$ at degeneracy 5 to about $\text{m = (1.9±0.2)}\text{κ}$ at degeneracy 15, relative to the SU(2) string tension $\text{κ}$.     

Gluon condensate and the interquark potential

We construct a potential for qurkonium systems using as the basic ingredients the gluon condensate, i.e., 〈0∥G_μν^aG_μν^a∥0〉 ≠ 0 to incorporate nonperturbative effects and using quark screening. The potential is able to account satisfactorily for the s$\text{s}$, c$\text{c}$ and b$\text{b}$ bound states with a flavor independent, essentially constant value for the effective coupling constant $\text{(}\text{α}{}_{\mathrm{<mtext>S</mtext>}}\text{≈ 0.45)}$. We also investigate heavier quark systems with the constant $\text{α}{}_{\mathrm{S}}$ and find that for quark mass ? 20 GeV the potential is essentially coulombic.     

A new potential for quarkonium

We suggest a new potential for bound states of a heavy quark-antiquark pair. This potential has a logarithmic piece interpolating between a confining linear part at large distances and an asymptotically free Coulombic part at short distances. We show that the logarithmic piece of our potential considerably influences the $\text{ψ}\text{J}$-family spectrum, and dominates the ?-family. An excellent fit to the $\text{psi;}\text{J}$ data below the DD? threshold and the correct ?′?? mass splitting is obtained in a natural way. We suggest a possible test for this new potential through the leptonic widths of the ?-family.     

Proton states in the N = 88 nuclei 149Pm, 151Eu and 153Tb populated in the (τ, d) and (α, t) reactions

The (τ, d) and (α, t) reaction on targets of ¹⁴⁸Nd, ¹⁵⁰Sm and ¹⁵²Gd have been studied, using beams of 24 MeV ³He and 27 MeV ⁴He from the McMaster University FN tandem Van de Graaff accelerator. The reaction products were analyzed with a magnetic spectrograph and detected with photographic emulsions. The (α, t) spectra were measured at two angles for each target, and the (τ, d) reactions were studied at 8 or 9 angles. The l-values for a number of low-spin states were determined from the (τ, d) angular distributions, and ratios of the (α, t) and (τ, d) cross sections were used to obtain l-values for several other states. There are some striking similarities in the observed structures of the three final nuclei, ¹⁴⁹Pm, ¹⁵¹Eu and ¹⁵³Tb. In each case there are low-lying strongly populated $\text{11}\text{2}$^? states and a higher lying l = 5 level somewhat below 1 MeV of excitation energy. Several states (10 in ¹⁴⁹Pm, 17 in ¹⁵¹Eu and 8 in ¹⁵³Tb) appear to be populated via l = 2 transitions, and there are strongly excited $\text{1}\text{2}$⁺ levels at $\text{≧ 1}\text{MeV}$ of excitation energy in each case. Of particular interest is a $\text{7}\text{2}$^? state located ≦ 50 keV above the lowest $\text{11}\text{2}$^? state in each nuclide. The relatively strong populations of these $\text{7}\text{2}$^? levels in the present experiments are contrary to expectations based on the simple shell model as there are no f_{$\text{7}\text{2}$} states in the 50 < Z < 82 shell.     

The reaction 55Mn(d, t)54Mn

Neutron pick-up cross sections and vector analyzing powers have been measured for the reaction ⁵⁵Mn($\text{d}$, t)⁵⁴Mn at 17 MeV. The mixture of $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ transfer to the low-lying l_n = 1 states has been found. Evidence of the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole nature of several strong l_n = 3 states above 1 MeV has been obtained.     

Apparent spin-dependent forces in QCD or the quantum chemistry of hadrons

Mesons in QCD are viewed as $\text{q}\text{q}$ pairs at the ends of a string (electric flux line). The (mass)² spectrum is approximately linear in the number of nodes, ν, in the wave function ψ(x), x being the fraction of total momentum carried by one quark. For the equal mass case ψ is even (odd) under reflection x ? (1 ? x) for ν even (odd). Thus this reflection symmetry is to be interpreted as charge conjugation where C = +1 (?1) respectively, and hence by Fermi statistics, singlets (triplets) in spin. Since the spectrum of (mass)² is evenly spaced in ν, one can represent the even and odd states by two Regge trajectories separated by intercept $\text{1}\text{2}$, thereby explaining the famous $\text{1}\text{2}$ intercept difference for the π, ρ system. The argument generalizes to K, K¹ as well, but must be further analyzed before we generalize it to baryons.