Eta Pi Research Articles

Search for the decay upsilon(1S) --> gammaeta(').

We report on a search for the radiative decay Upsilon(1S)-->gammaeta(') in 61.3 pb(-1) of data taken with the CLEO II detector at the Cornell Electron Storage Ring. Three decay chains were investigated, all involving eta(')-->pi(+)pi(-)eta, followed by eta-->gammagamma, eta-->pi(0)pi(0)pi(0), or eta-->pi(+)pi(-)pi(0). We find no candidate events in any of the three cases and set a combined upper limit of 1.6x10(-5) at 90% C.L., significantly smaller than the previous limit. We compare our result to other radiative Upsilon decays, to radiative J/psi decays, and to theoretical predictions.

Filter for strangeness in $J^{PC}$ exotic four-quark states

Symmetrization selection rules for the decay of four-quark states to two J=0 mesons are analysed in a non - field theoretic context with isospin symmetry. The OZI allowed decay of an isoscalar J^PC = (1,3,...)^{-+} exotic state to eta' eta or f_0' f_0 is only allowed for four-quark components of the state containing one s sbar pair, providing a filter for strangeness content in these states. Decays of four-quark a_0 states are narrower than otherwise expected. If the experimentally observed 1^{-+} enhancement in eta pi is resonant, it is qualitatively in agreement with being a four-quark state.

Experimental evidence for hadroproduction of exotic mesons

New measurements of peripheral meson production are presented. The data confirm the existence of exotic mesons at 1.4 and 1.6 GeV/c2. The latter state dominates the eta'pi- decay spectrum. The data on eta pi+pi-pi- decay show large strength in several exotic (Jpc = 1- +) waves as well.

Light scattering and viscosity study of heat aggregation of insulin.

Aggregation behavior and hydrodynamic parameters of insulin have been determined from static and dynamic light scattering experiments and intrinsic viscosity measurements carried out at pH 4.0, 7.5, and 9.0 in the temperature range 20-40 degrees C in aqueous solutions. The protein aggregated extensively at elevated temperatures in the acidic solutions. Intermolecular interactions were found to be attractive and to increase with temperature. The measured intrinsic viscosity [eta], diffusion coefficient D0, molecular weight M, and radius of gyration Rg exhibited the universal behavior: M[eta] = (2.4 +/- 02) x 10(-27) (Re, eta/Re, D)3(D0 eta 0/T)-3 and (D0 square root of n)-1 approximately equal to (square root of pi eta 0 xi beta/kBT) [1 + 0.201)(v/beta 3) square root of n], where n is the number of segments in the polypeptide. The effective hydrodynamic radii deduced from [eta], (Re, eta) and the same deduced from D0, (Re, D) showed a constant ratio, (Re, eta/Re, D = 1.1 +/- 0.1). Re, D/Rg = xi was found to be (0.76 +/- 0.07). From the known solvent viscosity eta 0, the segment length beta was deduced to be (10 +/- 1) A. The excluded volume was deduced to be (5 A)3 regardless of pH. The Flory-Huggins interaction parameter was found to be chi = 0.45 +/- 0.04, independent of pH and temperature.

Observation of the DecayDs+→ωπ+

Using e+e- annihilation data collected by the CLEO~II detector at CESR, we have observed the decay Ds+ to omega pi+. This final state may be produced through the annihilation decay of the Ds+, or through final state interactions. We find a branching ratio of [Gamma(Ds+ to omega pi+)/Gamma(Ds+ to eta pi+)]=0.16+-0.04+-0.03, where the first error is statistical and the second is systematic.

Calculation of translational friction and intrinsic viscosity. I. General formulation for arbitrarily shaped particles

A general method for calculating translational friction and intrinsic viscosity is developed through exploiting relations between hydrodynamics and electrostatics. An approximate relation xi = 6 pi eta 0C between the translational friction coefficient xi of a particle (eta 0: solvent viscosity) and its capacitance C was derived previously. This involved orientationally preaveraging the Oseen tensor, but the result was found to be very accurate. Based on preaveraging, we find that the intrinsic viscosity [eta] of a particle can be estimated from its polarizability alpha through [eta] = 3/4 alpha + 1/4 Vp, where Vp is the volume of the particle. Both the capacitance and the polarizability can be obtained in a single calculation using the boundary-element technique. An efficient approach is thus found for estimating [eta], a quantity that is very useful in practice because of its sensitivity to particle shape but is notoriously difficult to calculate. Illustrative calculations on ellipsoids, cylinders, and dumbbells demonstrate both the accuracy of the approximate relations and the efficiency of the present method.

Final state interactions in three-meson systems: Analysis of data on p-barp--> pi 0 pi 0 pi 0 and eta eta pi 0 at rest.

We provide a theoretical and computational formalism for the study of three-body annihilation of pp\ifmmode\bar\else\textasciimacron\fi{}. It includes (i) an analysis of three-body equations with the purpose of extracting the leading singularities and (ii) an analysis of low-energy \ensuremath{\pi}\ensuremath{\pi}, KK\ifmmode\bar\else\textasciimacron\fi{}, \ensuremath{\eta}\ensuremath{\eta}, and \ensuremath{\pi}\ensuremath{\eta} amplitudes and the reconstruction of them from available experimental data. Based on this formalism, we perform an analysis of data on pp\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$ and \ensuremath{\eta}\ensuremath{\eta}${\mathrm{\ensuremath{\pi}}}^{0}$ at rest. The data are fitted well by pure $^{1}$${\mathit{S}}_{0}$ annihilation and require two I=0,${\mathit{J}}^{\mathit{P}\mathit{C}}$=${0}^{++}$ resonances with ${\mathit{M}}_{1}$=1335\ifmmode\pm\else\textpm\fi{}40 MeV, ${\mathrm{\ensuremath{\Gamma}}}_{1}$=${255}_{\mathrm{\ensuremath{-}}40}^{+60}$ MeV, and ${\mathit{M}}_{2}$=1505\ifmmode\pm\else\textpm\fi{}20 MeV, ${\mathrm{\ensuremath{\Gamma}}}_{2}$=150\ifmmode\pm\else\textpm\fi{}20 MeV. The latter explains features of the data previously interpreted in an alternative way as due to ${\mathit{A}}_{\mathit{X}}$(1515) with ${\mathit{J}}^{\mathit{P}\mathit{C}}$=${2}^{++}$. As a second step, we evaluate the magnitude of the amplitudes due to triangle singularities which result from rescatterings of outgoing mesons. Taking into account these rescattering processes enhances the magnitudes of low-lying resonances, notably ${\mathit{f}}_{0}$(975).

Charged-particle thermonuclear reactions

An overview is presented on the subject of the theory of charged-particle thermonuclear reactions in the context of astrophysical nuclear reactions and in particular those processes occurring in stellar interiors. The authors discuss the energy dependence of charged-particle reaction cross sections for low energies which are governed by the Coulomb penetration factor and the de Broglie wavelength. Therefore it is common to transform the cross section into the so called astrophysical S-factor: S(E)= sigma (E).E.exp(2 pi eta ), where eta is the Sommerfeld parameter ( eta =Z1Z2e2/h(cross)v). The low energy tail of broad resonances or non-resonant processes can be studied experimentally down to a limiting energy El. However, the most interesting region for astrophysics is the vicinity of the Gamow peak, which arises at the overlap region of the Maxwell-Boltzmann distribution of the stellar plasma and the exponentially decreasing cross section. It is this region where the reaction rate is needed, but it is also the region which is hardly accessible by experiments. Therefore, the non-resonant contributions have to be extrapolated and the properties of the subthreshold resonances as well as other resonances located near the Gamow energy have to be investigated by other means. Possible techniques to approach reliable reaction rates are sketched. The most critical reactions for the solar v-problem are also discussed.

Predictions of neutron spectra for pd to pi 0 pi 0 pi 0n, pi 0 pi 0 eta n and pi 0 eta eta n at rest

The authors present predictions of spectator neutron spectra for pd to pi 0 pi 0 pi 0n, pi 0 pi eta n and pi 0 eta eta n at rest by considering tree and rescattering diagrams.

Partial-wave analysis of J/ psi --> gamma eta pi + pi -

We present a study of the decay {ital J}/{psi}{r arrow}{gamma}{eta}{pi}{sup +}{pi}{sup {minus}} using the Mark III detector at the SLAC {ital e}{sup +}{ital e{minus}} storage ring SPEAR. A partial-wave amplitude analysis is performed on the {eta}{pi}{sup +}{pi}{sup {minus}} system in the mass region from 1.2 to 1.5 GeV. We observe two {eta}{pi}{sup +}{pi}{sup {minus}} resonances, each decaying via {ital a}{sub 0}(980){pi}. We identify one as the axial-vector meson {ital f}{sub 1}(1285) and the other as a pseudoscalar resonance at 1.40 GeV.

Restrictions on tau ---> eta pi - nu in two-Higgs-doublet models.

We consider several phenomenological constraints for a large class of two-Higgs-doublet models. We show that a significant (>0.1%) branching ratio for the second-class decay ${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}\ensuremath{\eta}${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\nu} can be excluded for the models satisfying the ``naturalness'' requirements of Glashow and Weinberg. If one of these requirements is relaxed, a substantial (>1%) branching ratio for this mode cannot be ruled out, but this requires a rather large coupling to the \ensuremath{\tau} lepton. Implications for pp\ifmmode\bar\else\textasciimacron\fi{} and pp experiments are briefly discussed.

Finite-size scaling for directed bond percolation with and without cycles on a triangular lattice

The authors apply finite-size scaling and phenomenological renormalisation group arguments to the problems of directed acyclic, directed cyclic and undirected bond percolation on a triangular lattice. The results are in good agreement with known estimates, and show that the phenomenological renormalisation procedure is sensitive to the difference between global and local directional biases, as well as the distinction between locally directed and fully isotropic problems. In addition, the authors draw tentative comments on the extension, to directed problems, of the relation A= pi eta (where A is the inverse correlation length amplitude of a strip of finite width at criticality and eta is the exponent that describes the decay of correlations at the critical point), known to hold for various isotropic systems.

Gluon admixtures in the 0-neutral mesons: a survey of the quark-line rule

Gluon admixtures in neutral pseudoscalar mesons are considered to test the quark-line rule for the reactions pi p to eta Delta , eta n, pp to pi pi eta , etc. It is found that the experimental data on these reactions support the possibility of a small gluonium admixture in the eta and eta ' states. The results have also been used to predict some electromagnetic decay rates of the pseudoscalar glueball states l(1440) along with those of eta and eta '.

Correlation length in Ising strips with free and fixed boundary conditions

The correlation length of boundary spins in the Ising model, defined on strips of triangular lattice with free boundary conditions, is determined with an efficient numerical procedure based on the star-triangle transformation. In the case of isotropic critical interactions, the extrapolated amplitude of the correlation length is in excellent agreement with the value 2/( pi eta /sub ///) predicted by conformal invariance. An analytical formula for the amplitude in strips with anisotropic interactions is proposed. Fixing the spins on one edge reduces the amplitude of the correlation length on the other edge by a factor 1/2. The convergence of phenomenological renormalisation with free boundary conditions is studied.

Qualitative and quantitative methods for detecting staphylococcal epidermolytic toxin.

Concentrated supernates of cultures of 98 strains of Staphylococcus aureus were screened for the production of epidermolytic toxin by (1) biological tests in 3-day-old mice, (2) double-diffusion precipitation tests against specific antiserum, and (3) the appearance of characteristic protein bands on thin-layer-gel isoelectric focusing. Positive results were obtained in all three of these tests with supernates from 11 of these cultures; the same 11 strains, and no others, produced epidermal splitting when newborn mice were challenged with viable organisms. Of the 14 phage-group II strains included in the survey, eight (58%) produced epidermolytic toxin. Three toxinogenic strains belonged to phage groups other than group II. A radial-immunodiffusion test employing antiserum to purified epidermolytic toxin proved satisfactory for measuring amounts of epidermolytic toxin in excess of 200 mug per ml. The results of immunodiffusion tests indicated that six of the 11 positive strains produced two serologically distinct forms of epidermolytic toxin and that the remainder produced only one of these. A striking correlation was observed between the presence of toxin of serotypes i and ii and the occurrence of protein bands i and ii in thin-layer isoelectric-focusing gels. These tests should facilitate the qualitative and quantitative assessment of the production of different serotypes of epidermolytic toxin by S. aureus in future surveys of strains isolated from toxic epidermal necrolysis of Ritter's type and impetigo. The two forms of epidermolytic toxin previously designated ETA (pI=7-0) and ETB (pI=6-0) were detected by preparative isoelectric focusing of sero-type-i toxin. Evidence suggests that studies of the effect of heat should provide a means of investigating the relationship between the different molecular forms of epidermolytic toxin.

The General Law of Fall of a Small Spherical Body through a Gas, and its Bearing upon the Nature of Molecular Reflection from Surfaces

Law of fall of a small spherical body through a gas at any pressure.—(1) Theoretical derivation. When the ratio of free path to radius of droplet, l / a, is small, the resistance to motion is due entirely to viscosity and is proportional to a, while when l / a is large the resistance is due entirely to the inertia of the molecules hit and is proportional to a^2. The equation: F=6 pi eta av [1+A'l / a]-1 satisfies both these theoretical conditions. From Kinetic theory, however, it has been shown that A' is not constant but varies from a lower theoretical limit of.7004 (diffuse reflection) for l / a small, to 1.164 for l / a large. We therefore put A'=A+B epsilon -ca / l and write the complete equation: F=6 pi eta av [1+(A+B epsilon -ca / l)l / a]-1. (2) Experimental verification. By the oil drop method, values of A' have been determined for a wide range of values of l / a, from 0.5 to 134, for oil drops in air. These results are found to agree within the experimental error of ±2 per cent or less with the theoretical equation, and give A=.864, B=0.290, c=1.25. A discussion of results obtained with other drops indicates that while A varies with the nature of the gas and even more with the material of the droplet, (A+B) is within two or three per cent the same for most sorts of particles which might settle through the atmosphere. (3) Differentiation between diffuse reflection, specular reflection, radial reflection, and condensation and re-evaporation of molecules. Radial reflection is shown to be thermodynamically and dynamically impossible; condensation and re-evaporation to be inconsistent with the observed value of (A+B). This observed value is satisfied only by a combination of about 1/10 of specular reflection with 9/10 of diffuse reflection, this last being defined as a reemission from each element of surface and in such directions as to satisfy the Maxwell distribution law, of all molecules which impinge upon that element. The agreement adds new evidence for the existence of specular reflection of molecules since 1/10 had also been indicated by the values of A previously obtained for oil-drops in air. (4) Effects of mechanical roughness of the surface. The apparent discrepancies between the author's results and those of Knudsen and Gaede, which seemed to indicate complete diffuse reflection, are explained by the effects of minute mechanical proturberances which are thought to have existed on the insides of these authors' capillary tubes.