Search for the formation of new particles in pp reactions near 3 GeV

Using the multiparticle spectrometer facility (MPS) at BNL, we have set upper limits on the formation of a meson state in the mass range 2.99–3.14 GeV from proton-anti-proton annihilations. The upper limits are, in terms of the cross section integrated over the width, 18 MeV · μb for the final state $\text{γ}\text{γ}\text{, 18}\text{MeV}\text{·}\text{for K}{}^0\text{K}{}^{01}\text{(890) +}\text{c.c.}$, and 2 MeV · μb for K_SK_L.     

Anomalous specific heat in La : Ce alloys

The magnetic contribution to the specific heat in La : Ce alloys shows a broad anomaly at ≈ 1.2°K which is weakly dependent on the concentration. This anomaly, which accounts for a substantial portion of the entropy of a doublet, cannot be attributed to either usual magnetic ordering or to a dilute alloy Kondo effect, but may represent the behavior of a concentrated Kondo system.     

On the length of linked curves

If two curves inR ³ are linked and at distance 1 from each other then each is of length 2π at least.     

On existence and approximate solutions for a nonlinear integral equation arising in the theory of creep in metals

Existence of a solution to a nonlinear integral equation arising in the theory of creep in symmetric pressure vessels is established by means of a recursively defined sequence of functions. It is shown that this sequence converges monotonically and uniformly to the solution.

---

Zusammenfassung Das Problem des Kriechens in symmetrischen Druckgefässen führt auf eine nichtlineare Integralgleichung. Zum Beweis der Existenz einer Lösung dieser Gleichung wird rekursiv eine Folge von Näherungslösungen konstruiert. Es wird gezeigt, dass diese Folge monoton und gleichmässig nach der Lösung der Integralgleichung konvergiert.

---

---

This research was supported by the National Science Foundation under Grant MPS-75-07450.     

Dichroism of impurity crystals without inversion center induced by energy term linear in wavevector

The effect of a parity violation in hexagonal crystals without inversion center has been investigated. The transition 1s-2s of an electron bound to a donor is shown to be dipole allowed. In a weak magnetic field the spin-flip transitions take place only at a definite sign of a photon circulation. Their intensities is almost independent of the value of the magnetic field.     

Identification of new N-Sb topologies: understanding the sequential dehydrochloride coupling of primary amines and trichloropnictines

Subtle steric strain imposed by 2,6-dimethylphenyl substituents on N-Sb frameworks has enabled identification of the first acyclic dipnictadiazane and the first six-membered cyclotristibatriazane providing insight into the dehydrohalide coupling reaction of amines with halopnictines.     

BaO(X 1Σ+) vibrational relaxation

Vibrationally excited BaO(X ¹Σ⁺) was produced by reacting Ba atoms with O₂ under “jet flow” conditions in which the convective flow velocity was large compared with the diffusion velocities so that the relaxation could be spatially resolved. The vibrational level populations were determined by laser-induced fluorescence measurements. By using modeling calculations to fit the spatial variation of the apparent vibrational temperature, we obtained a vibrational relaxation rate for BaO(X ¹Σ⁺), ν = 1 → ν = 0, by Ar, of 9 × 10^?13 cm³/molecule s.     

A unified analysis for a class of long-step primal-dual path-following interior-point algorithms for semidefinite programming

We present a unified analysis for a class of long-step primal-dual path-following algorithms for semidefinite programming whose search directions are obtained through linearization of the symmetrized equation of the central pathH _P (XS) [PXSP ^–1 + (PXSP ^–1) ^T ]/2 = I, introduced by Zhang. At an iterate (X,S), we choose a scaling matrixP from the class of nonsingular matricesP such thatPXSP ^–1 is symmetric. This class of matrices includes the three well-known choices, namely:P = S ^1/2 andP = X ^–1/2 proposed by Monteiro, and the matrixP corresponding to the Nesterov—Todd direction. We show that within the class of algorithms studied in this paper, the one based on the Nesterov—Todd direction has the lowest possible iteration-complexity bound that can provably be derived from our analysis. More specifically, its iteration-complexity bound is of the same order as that of the corresponding long-step primal-dual path-following algorithm for linear programming introduced by Kojima, Mizuno and Yoshise. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Corresponding author.This author's research is supported in part by the National Science Foundation under grants INT-9600343 and CCR-9700448 and the Office of Naval Research under grant N00014-94-1-0340.This author's research was supported in part by DOE DE-FG02-93ER25171-A001.     

Effect of asymmetry of CuO2 layers in copper oxides on the anomalous neutron scattering near T c

Reasons for critical magnetic scattering of neutrons near T _c in copper oxides with CuO₂ layers whose nearest environment has no “up-down” symmetry are discussed. The intracrystalline electric field, which threads the CuO₂ planes on account of the asymmetry, induces coupling between the spin and momentum of the current carriers. This coupling is shown to result in a manifestation of virtual Cooper pairs in the imaginary part of the spin susceptibility. Thus spin density fluctuations as well as current fluctuations should participate in the scattering. A way of experimentally distinguishing between the two mechanisms is pointed out. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 5, 363–368 (10 March 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.