19F NMR in the S=12 antiferromagnets CuF2 and AgaF2

¹⁹F NMR has been observed in the antiferromagnetic phases of CuF₂ and AgF₂. These compounds, which are known to have very similar magnetic structures, have been shown to have similar magnetization curves and to have saturation sublattice magnetizations that scale approximately as their Neel temperatures.     

Possible origin of S =12 ESR lines in alkali-TCNQ Salts

Solitons in spin Peierls systems are studied with emphasis on the contribution of solitions to the ESR spectra. It is pointed out that the ESR line ($\text{S =}\text{1}\text{2}$) observed in simple alkali-TCNQ salts can be due to solitons in spin Peierls state.     

Comparison of pp and pp interactions at s = 53 GeV

Results are presented from the first p$\text{p}$ colliding beam runs at the CERN ISR, using the UA5 streamer chamber detector. p$\text{p}$ interactions at $\text{s}\text{= 53}\text{GeV}$ are compared with pp data taken in the same experiment. The results are in good agreement with extrapolations of low-energy p$\text{p}$ data.     

Susceptibilities of the S = 12 XY model on the square lattice at T = 0

For the $\text{S =}\text{1}\text{2}\text{XY}$ model at T = 0 four susceptibilities have been calculated exactly on a sequence of finite square lattices and extrapolated to the infinite square lattice. For the ferromagnet χ_zz = 0 while χ_xx ～ N^2.9; for the antiferromagnet $\text{J}{}_{\mathrm{\chi xx}}\text{N(gμ}{}_{\mathrm{<mtext>B</mtext>}}\text{)}{}^2\text{= 0.025 ± 0.002}$ and $\text{J}{}_{\mathrm{\chi xx}}\text{N(gμ}{}_{\mathrm{<mtext>B</mtext>}}\text{)}{}^2\text{= 0.13 ± 0.03}$.     

Quark-tadpole origin of the ΔI = 12 rule

In the context of a two-quark field picture of current quarks and renormalized constituent quarks, we show that an s-d current-quark tadpole generated by the weak Cabbibo-GIM current appears in the current-quark nonleptonic ΔY = 1 hamiltonian. Then we demonstrate that this $\text{ΔI =}\text{1}\text{2}$ operator in fact sets the observed scale of the K_s→ππ decays without recourse to any fitted parameters.     

On spin-52 gauge fields

We present and discuss the theory of free, massless gauge fields with spin $\text{5}\text{2}$.     

The quark sea and the ΔI = 12 rule

The effect on nonleptonic processes of quark-antiquark pairs due to quantum chromodynamics is studied. Their presence improves agreement between theory and experiment for hyperon decays. In kaon decays a new $\text{ΔI =}\text{1}\text{2}$ contribution is found, but $\text{Δ =}\text{3}\text{2}$ effects are still large to to be in agreement.     

Origin of 1ƒ noise

$\text{1}\text{?}$ noise dependence on temperature for both n- and p-type silicon has been measured. The formula for calculation of $\text{1}\text{?}$ noise is presented. The formula has been derived by presumption that only lattice scattering gives $\text{1}\text{?}$ noise. A good agreement between calculations and experimental results is found.     

Some studies of T = 32 states in 17F

Measurements have been made of some parameters of the second and sixth $\text{T =}\text{3}\text{2}$ states in ¹⁷F. For the second state, the resonance energy was found to be E_p = 12.707 ± 0.001 MeV (E_n = 12.550±0.001 MeV), which agrees with and improves on the accuracy of earlier work. For the sixth $\text{T =}\text{3}\text{2}$ state, at E_p = 14.435 MeV, the γ-decay was determined to be predominantly γ₀ with a branch to the first excited state of Γ(γ₁)/Γ(γ₀) ≦ 0.14. Together with other work, this determines J^π to be $\text{3}\text{2}{}^{\mathrm{?}}$. The capture strength is found to be (2J + 1)Γ_pΓ_γ/Γ = 11.4 ± 2.6 eV.     

Effects of the uniaxial anisotropy on the Curie temperature of the anisotropic Heisenberg ferromagnet with mixed spins S = 12 and S = 1

With the use of the pair model approximation, the effects of the D-term on the Curie temperature of the anisotropic Heisenberg ferromagnet with mixed spins $\text{S =}\text{1}\text{2}$ have been investigated and shown to be significant for D > 0.     

Structures in pp → ππ

A Barrelet-zero analysis is presented of data on $\text{p}\text{p}\text{→ π π}$ in the momentum range 1 to 2 GeV/c. With π^?π⁺ data alone, the slope for ambiguity is very large, but the addition of π⁰π⁰ information enables the number of solutions to be reduced to just a few. Although the alternative solutions differ considerably, they significant common features, in particular, with plausible extra assumptions, all solutions appear to be dominated by resonances in all spin states from J = 1 to 5.     

Scattering of solitons with fermion number ±12

In a model of a Dirac field coupled to a sine-Gordon system, we have soliton solutions with half-integral fermion number. Scattering problems of such solitons are investigated. For soliton-soliton and soliton-antisoliton solutions, we find explicit solutions to the Dirac equations which are localized at the position of the (anti-)solitons. It is shown that the fermion number is generally transferred between the soliton and the (anti-)soliton in the scattering process.     

The spin 12 gravitational anomalous magnetic moment

The gravitational anomalous magnetic moment of a spin $\text{1}\text{2}$ particle is calculated and compared with an earlier dimensional regularization result. The answers disagree although both agree the answer is finite. It is argued that this quantity is not uniquely determined by physical requirements. The methods used are shown to respect the gravitational and electromagnetic gauge invariances. In addition, a physical interpretation of the regularization method employed is offered.     

Relativistic transport equation for spin 12 particles

For the model of positive energy Dirac particles with short range interaction a transport equation for the one- particle Wigner function is obtained. This transport equation is a generalization of the non-relativistic Walsmann- Snider equation for spin particles.     

Spectrum and damping in quadrupolar biquadratic systems (S=32)

Using the diagrammatic technique for Stevens operators the spectrum and the damping of elementary excitations for the doublet-doublet biquadratic systems are calculated in the $\text{(}\text{1}\text{z}\text{)}{}^1$ approximation.     

Energies of the n2S12 and n2D32,52 states of Cs

Using the technique of Doppler-free two-photon spectroscopy the energies of the n²S_{$\text{1}\text{2}$} (12 ? n ? 35) and n²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} (11 ? n ? 48) states of CsI have been measured with a thermionic detector. The absorption spectrum of molecular iodine was used as a reference giving us a total estimated accuracy of about 2 × 10^-7. Taking also into account the energies of the 7–11 ²S_{$\text{1}\text{2}$} and 5 and 6 ²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} states measured by other authors and using an extended Ritz-formula we found the ionization limit to be E_i = 31406.468 ± 0.006 cm^-1.     

The ΔI = 12 rule with heavy quarks and right-handed currents

The effect of strong interactions on a two-fermion operator is calculated in an asymptotically free theory, thereby completing the calculation of the logarithmic exponents for the operators contributing to non-leptonic amplitudes. The case of models with both left-and right-handed weak currents is discussed and the implications for the $\text{ΔI=}\text{1}\text{2}$ rule and other non-leptonic decays are deduced.     

On the spectrum of singlet excitations of the S = 12 linear Heisenberg antiferromagnet

We note that available numerical data for the spectrum of small antiferromagnetic Heisenberg rings with nearest neighbour interaction, and $\text{S}\text{=}\text{1}\text{2}$ facilitate an extrapolation giving some idea of the form of the lower edge of the spectrum of singlet excitations for the infinite system. The result we obtain is radically different from the one given by Ovchinnikov in two respects: the singlet excitations are roughly equally distributed over the whole Brillouin zone, and the shape is better approximated by the formula valid for the triplet spectrum. A proof that there is a continuum of singlet excitations for every wave number is given.     

Optimal sum-rule inequalities for spin-12 compton scattering

A formalism appropriate for model-independent dispersion theoretical investigations of the (not necessarily forward) Compton scattering off $\text{spin}\text{-}\text{1}\text{2}$ hadronic targets, which fully exploits the analyticity properties of the amplitudes (to lowest order in electromagnetism) in ν² at fixed t ($\text{ν =}\text{1}\text{4}\text{(s ? u); s, t}$, u = Mandelstam variables), is developed. It relies on methods which are specific to boundary-value problems for analytic matrix-valued functions. An analytic factorization of the positive definite hermitian matrix associated with the bilinear expression of the unpolarized differential cross section (u.d.c.s.) in terms of the Bardeen-Tung (B.T.) invariant amplitudes is explicitly obtained. For t in a specified portion of the physical region, six new amplitudes describing the process are thereby constructed which have the same good analyticity structure in ν² as the (crossing symmetrized) B.T. amplitudes, while their connection with the usual helicity amplitudes is given by a matrix which is unitary on the unitarity cut. A bound on a certain integral over the u.d.c.s. above the first inelastic threshold, established in terms of the target's charge and anomalous magnetic moment, improves a previous weaker result, being now optimal under the information accepted as known.