Hybrids: Mixed states of quarks and gluons

We calculate the spectrum of the four ground state hybrid $\text{(}\text{q}\text{qg}\text{)}$ nonets, J^PC = (0, 1, 2)^?+, 1^??, using the MIT bag model to first order in cavity perturbation theory. Quark and gluon self-energies are included by a fit to the s-wave mesons and baryons and to the glueball candidate i(1440). We find a large gluon self-energy which substantially increases our predictions of the glueball and hybrid masses. We discuss the phenomenology of hybrids, including a suggestion that the A₃ (1670) and a second peak at 1850 MeV in the fπ channel may be mixtures of the isovector $\text{q}\text{q}$ d-wave state with the $\text{q}\text{qg}$ s-wave.     

Polarization spectroscopy of ICl: The D′, a and a′ states

Three previously-unanalyzed states of ICl are reported, an ion-pair state D′(Ω =2) which converges to the limit I⁺(P₂+ Cl^-(S_o), and two shallow states a(Ω = 1) and a′(Ω = 0⁺) both of which converge to the ground states of separated atoms I(P_{$\text{3}\text{2}$}) + Cl(P_{$\text{3}\text{2}$}). The a(0⁺) state is responsible for the well-known interruption of the B(0⁺) state above υ_B = 3. Spectroscopic constants are given for the D′ and a′ states.     

Spin-parity analysis of the nπ+ system produced in the reaction π+p → π+π+n at 16GeV/c

A spin-parity analysis of the nπ⁺ system produced in the reaction π⁺p → π⁺π⁺n at 16 MeV/c has shown apart from the mass enhancements associated with the known resonances Δ⁺(1238), N¹(1520) and N¹(1688) there is an enhancement peaked at M(nπ⁺) ? 1.35 GeV, ∑0.2 GeV wide. For masses below M(nπ⁺) ? 1.35 GeV this enhancement is predominantly due to $\text{J}{}^{\mathrm{P}}\text{=}\text{1}\text{2}{}^{\mathrm{?}}$ states, predominate. The presence of $\text{J}{}^{\mathrm{P}}\text{=}\text{1}\text{2}{}^{\mathrm{?}}$ states indicates that the rule ΔP = (?1)^ΔJ is strongly violated in the diffractive process N → Nπ, and hence it cannot be considered a specific characteristic of all diffractive processes.     

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.     

A study of the Regge recurrence of the Δ(1236) produced in 10 GeV/c K+p interactions

Data are presented on a high mass $\text{I}\text{3}\text{2}\text{Δ}$ resonance produced in 10 GeV/c K⁺p interactions. The mass and width of the resonance, determined by a maximum likelihood fit to the pπ⁺ spectrum in the final state K⁺pπ⁺π^?, are 1895±15 MeV/c²230±50 MeV/c² respectively. The differential cross sections, dσ/dt, for the quasi two-body final states K¹(890)Δ(1236) and K¹(890)Δ(1900) are well described by the one pion exchange model. In addition the moments of the Gottfried-Jackson angular distribution of the pπ⁺ system agree with those computed from on-shell π⁺p elastic scattering data. We conclude that the two final states are produced mainly by π exchange and associate the structure observed in the moments up to NH(6,0) in the 1900 MeV region with the $\text{7}\text{2}{}^{\mathrm{+}}$ Regge recurrence of the Δ(1236). The dominant decay mode of the resonance is Δ⁺⁺(1900)→pπ⁺ but decays to pπ⁺π⁰ and nπ⁺π⁺ are also observed. Cross sections are determined for the production of the quasi two-body final states K¹(890)Δ(1236), K¹(890) Δ(1900), K¹(1420)Δ(1236) and K¹(1420)Δ(1900).     

Operator symbols in the description of observable-state systems

For an observable-state system with finite degrees of freedom N topological properties of the kernels and symbols belonging to the considered operators are investigated. For the operators of $\text{L}$⁺($\text{S}$) kernels and symbols are distributions and for density matrices o? they are smooth functions.     

A search for stable particles heavier than the proton and for Q = −23 quarks produced in e+e− annihilation

We have searched 1.4 × 10⁶e⁺e^? annihilation events for particles with 1–3 GeV/c² mass and charge $\text{Q = ?}\text{2}\text{3}$ from the processes e⁺e^?→q$\text{q}$X and e⁺e^? → q$\text{q}$. Upper limits of RQ ～ 10^?4 for each process are presented which improve the previous limits on free quark production in electromagnetic interactions by 2 orders of magnitude.     

A new electronic band system of PbO

The chemiluminescence spectrum of atomic Pb reacting with O₃ under single-collision conditions includes a series of 55 bands in the regions 450–850 nm. A vibrational analysis is obtained which shows emission is to the ground state of PbO from excited electronic states not previously analyzed. Forty-nine of the bands are assigned to the a(1)-X(0⁺) transition and the remaining six are tentatively identified as the forbidden b(0^?)-X(0⁺) transition. Both the a and b states are believed to be Hund's case (c) components of the ³Σ⁺ states arising from the configuration $\text{σ}{}^2\text{π}{}^3\text{π}{}^1$. The vibrational parameters of the a state are ν₄ = 16 029 ± 8, ω_e′ = 478.7 ± 1.9, and ω_ex_e′ = 2.292 ± 0.128 cm^?1, where the uncertainties represent two standard deviations of the least-squares fit. Emission is also observed from the PbO B state produced in the reaction of metastable Pb atoms with O₃. Using pulsed laser excitation, an attempt is made to determine radiative lifetimes. We find for the PbO A(0⁺) state τ = 3.74 ± 0.3 μsec, and for the PbO B(1) state τ = 2.58 ± 0.3 μsec, while for the a(1) state τ is estimated to be greater than 10 μsec. From the vibrational analysis, energy conservation arguments place a lower limits to the ground state dissociation energy of $\text{D}{}_0{}^0\text{(}\text{PbO}\text{) ≥ 3.74 ± 0.03}\text{eV}$ (86.2 ± 0.7 kcal/mole). For the Pb + O₃ reaction we find less than 1% of the products are PbO¹ molecules that emit in the visible. Correlations are made with the low-lying states of other Group IV chalconides based on the assignment of the PbO $\text{a}{}^3\text{Σ}{}^{\mathrm{+}}\text{(1)}$ state and the correspondence between the low-lying triplet states of PbO and CO.     

Neutral heavy lepton candidate in e+e− interactions

An event of the form e⁺e^? → μ⁺μ^? + (2 jets) recently observed at √s = 43.45 GeV is interpreted as production of a pair of neutral heavy leptons N, each with mass 20.5 ± 1.0 Gev/c². Two possibilities are explored: (i) the lepton is a wak isodoublet neutrino, produced in pairs by virtual Z⁰ decay. In this case, one expects $\text{B(}\text{Z}{}^0\text{→}\text{N}\text{N}\text{) ≈ 5\%}$; (ii) the lepton is a “right-handed neutrino”, produced in pairs via a new vector boson Z_χ. In this case, in one model, the Z_χ must lie between about 50 and 67 GeV/c². More generally, it must be very weakly coupled to ordinary quarks and leptons in order not to conflict with low-q² neutral-current data. Suggestions are made for further observation of N$\text{N}$ pairs and other effects of Z_χ in forthcoming e⁺e^? and p$\text{p}$ collisions.     

Elementary-particle treatment of the radiative muon capture in 12C

We consider radiative muon capture to a definite nuclear final state. The example chosen is the ${}^{12}\text{C}\text{(0}{}^{\mathrm{+}}\text{T = 0)(μ}{}^{\mathrm{?}}\text{, γν)}{}^{12}\text{B}\text{(1}{}^{\mathrm{+}}\text{T = 1)}$ transition. The elementary particle treatment adopted in this work discloses several aspects of the reaction mechanism, which remain hidden in the usual impulse approximation calculations. In particular, one sees a considerable enhancement of the capture rate when the q² dependence of the weak form factors F_A(q²) and F_P(q²) is taken into account. The branching ratio of the radiative capture in the region sensitive to the possibly non-zero mass m_νμ of the muon-neutrino is estimated to be ≈1.36 × 10^?10.     

Morphogenesis of sliced N-soliton solutions

Consider an instantaneous severing interaction which at t = t_s transforms is given N-soliton solution q⁰ into two new solutions, q^L and q^R, with discontinuous anitial conditions at t = t_s such that q^L(q^R) is equal to q⁰ to the left (right) of the severing point x_s and vanishes to the right (left) of x_s. The soliton content of q^L and q^R is studied in the context of the cubic Schrödinger equation and the sine-Gordon equation by solving the direct scattering problem. It is shown that the motion constants C_n, n = 1, 2 …, are related by , Furthermore, if q⁰ contains N solitons and no contribution from the continuous spectrum, then q^L(q^R) contains N^L(N^R) solitons with 0 ? N^L, N^R ? N and N^L + N^R = N. The slicing puts a soliton into q^L or q^R, respectively as the slicing point x_s is taken to the right or left of the soliton's “center” at t = t_s.     

The fine structure of the spectrum of the electronic NO laser

The spectrum of the electronic NO laser has been photographed with high resolution in the region 10 100–10 500 Å. It shows the band system F²Δ-C²Π whose upper and lower states are both Rydberg states configurationally mixed with valence states. Only predissociated rotational levels of the lower state appear in the spectrum. For v = 0 of C²Π a single mixed level $\text{T}{}_{\mathrm{y}}\text{(J = 5}\text{1}\text{2}\text{) = 52431}\text{cm}{}^{\mathrm{?1}}$, very close to the dissociation limit, gives rise to laser lines.     

Quantum integrable systems related to lie algebras

Some quantum integrable finite-dimensional systems related to Lie algebras are considered. This review continues the previous review of the same authors [83] devoted to the classical aspects of these systems. The dynamics of some of these systems is closely related to free motion in symmetric spaces. Using this connection with the theory of symmetric spaces some results such as the forms of spectra, wave functions, S-matrices, quantum integrals of motion are derived. In specific cases the considered systems describe the one-dimensional n-body systems interacting pairwise via potentials g²v(q) of the following 5 types: v_I(q) = q^?2, v_II(q) = sinh^?2q, v_III(q) = sin^?2q, $\text{v}{}_{\mathrm{<mtext>IV</mtext>}}\text{(q) =}\text{P}\text{(q)}$, v_V(q) = q^?2 + ω²q². Here $\text{P}\text{(q)}$ is the Weierstrass function, so that the first three cases are merely subcases of the fourth. The system characterized by the Toda nearest-neighbour potential exp(q_jq_{j+ 1}) is moreover considered.This review presents from a general and universal point of view results obtained mainly over the past fifteen years. Besides, it contains some new results both of physical and mathematical interest.     

Free energies of the spherical model of a spin glass

Free energies g(m, m_s) and f(m, q) of the spherical spin glass (SG) model due to Kosterlitz et al. are calculated explicitly as functions of the uniform magnetization m, and SG order parameter m_s and the Edwards-Anderson order parameter q. It is shown that g(0, m_s) and f(0, q) below the transition temperature T_g are constant in the ranges 0 ≦ m_s ≦ m_s⁰ and 0 ≦ q ≦ q₀ respectively, where $\text{q}{}_0\text{= (1 -?}\text{T}\text{T}{}_{\mathrm{g}}\text{) = m}{}^2{}_{\mathrm{s}}{}^0$. The proper equilibrium values of m_s( = m_s⁰) and q( d=q₀) are then fixed from the inspection of their behaviors under infinitesimal uniform field proproportional to N^-a($\text{a ≧ 0}$).     

An experimental study of the form factor in the decay K+ → πoe+ν

The q² variation of the factor $\text{?}{}_{\mathrm{+}}\text{(q}{}^2\text{)}$ in the decay K⁺→π⁰e⁺ν has been studied using a sample of even detected in the CERN 1.1 m³ heavy-liquid bubble chamber. The data are consistent with a linear development $\text{?}{}_{\mathrm{+}}\text{(q}{}^2\text{)=?}{}_{\mathrm{+}}\text{(0) (1+λ}{}_{\mathrm{+}}\text{q/m}{}^2{}_{\mathrm{\pi }}\text{)}$ with λ₊=0.027±0.008.     

A comparison of πππ, Kππ, πKKKK system produced in the reactions meson +p→3 mesons + p

A comparison is made of the low-mass three-meson systems (πππ), (Kππ), $\text{(π}\text{K}\text{K}\text{)}$ and $\text{(}\text{K}\text{K}\text{K}\text{)}$ diffractively produced in the reaction meson + proton → three mesons + proton. Several striking similarities and a few important differences are observed: (i) the reactions are consistent with the assumption that the three mesons decay entirely into a 0^? meson and a 0⁺, 1^? or 2⁺ resonance; (ii) the three-meson mass spectra have a peak ≈ 250 MeV above the effective threshold M_eff of the dominant decay mode and then fall off approximately as (mass)^?3;(iii) the average spin 〈J〉 = 0.55 + 1.1 Q_eff, where Q_eff = M - M_eff; (iv) the average orbital angular momentum 〈l〉 increases according to 〈l〉 = 0.75 Q_eff; (v) the three-meson states are produced dominantly in unnatural spin-parity states and no evidence for their being resonant is found; (vi) the only natural spin-parity states found are the well-established 2⁺ resonances A₂ and K¹ (1420); they have similar properties to the non-resonant unnatural parity states except for a dip at t = 0 in the dσ/dt distributions; (vii) both the unnatural and natural spin-parity states are produced mostly by an exchange of natural parity; (viii) there is evidence for two types of production mechanism with different polarization properties, one approximately conserving helicity in the t-channel and the other in the s-channel.