Lambda Sigma Research Articles

A theory of the saturable ohmic channel

Let the passage of type-lambda ions through a type-sigma channel be determined only by the ionic valence z lambda, by the thermal energy kT, by the ion concentrations on the out- and in- sides [S lambda]o and [S lambda]i, by the inside with-respect-to outside voltage of the channel E, by a single descriptor of channel saturation [S sigma lambda], and by a single descriptor (permeance) the ease of channel transit P sigma lambda. Then, if the channel current i sigma lambda, due to lambda-ions is ohmic about the Nernst potential, is a function of the sum ([S lambda]o + [S lambda]i) and not of [S lambda]o or [S lambda]i independently, and saturates in a Michaelis-Menten fashion, it follows that (Formula: see text) where F is the Faraday constant.

'Partitions' in the perturbation theory of n-electron systems. II. The second-order eigenfunction

For pt.I see Int. J. Quantum Chem., vol.24, no.6, p.551-70 (1983). In the perturbation theory of the general n-electron system, H(n)= Sigma nf(i)+ lambda Sigma ng(i,j), the authors understand by a 'partition' of the rth-order eigenfunction a finite decomposition into eigenfunctions of subsystems H(n1), n1<n. Under the assumption of 'strict non-degeneracy', they prove the existence of a 'partition' for the second-order eigenfunction psi (2)(n). The components are psi (2)(n1=2), psi (2)(n1=3), psi (1)(n1=2); they belong to the (highly excited) two- and three-electron states which arise by multiple ionisation of the given n-electron state. The smallest system such that psi (2)(n) possesses a non-trivial 'partition' has four electrons.

Quantal and semiclassical methods in relativistic electromagnetic excitation.

Two different quantal approaches to describe relativistic Coulomb excitation are compared and proven to be equivalent in their basic formulations. We reanalyze the ..lambda sigma../sup 0/ conversion experiment by means of the plane wave Born approximation and we also discuss the possible applications of this approach to ultrarelativistic Coulomb collision experiments.

Transmission bandwidth properties of GeO_2-P_2O_5-doped silica graded-index optical fibers

Transmission bandwidth properties of GeO(2)-P(2)O(5)-doped silica graded-index fibers have been investigated. Theoretical results obtained from Olshansky's theory are represented in the form of a bandwidth map with profile parameter alpha on the vertical axis and wavelength lambda horizontally. The material dispersion sigma(m)(lambda) and the optimal profile parameter alpha(opt)(lambda) determined by the glass refractive-index measurement are used for calculating the transmission bandwidth. It is confirmed that the estimated results from the bandwidth map agree with the experimental results of transmission bandwidth measurements at lambda = 0.82,1.06,1.27, and 1.52 microm for twenty GeO(2)-P(2)O(5)-doped silica graded-index fibers with different alpha values.

Pion-hyperon couplings from the Adler conditions

The Adler constraints on the invariant amplitudes for the inelastic processes KN to Lambda pi and pi Lambda to pi Sigma are obtained in the soft pion limit. The numerical estimates of these consistency conditions are then used to determine pi Lambda Sigma and pi Sigma Sigma coupling constants.

Constraints on the KNY coupling constants

A domain of allowed values of the KN Lambda and KN Sigma coupling constants is constructed by applying the maximum modulus theorem and a factorisation theorem and making use of the data on the modulus of the K+or-p forward scattering amplitude on its cuts. It is shown that there is a strong correlation between the positions of the zeros of the amplitude and the strengths of its poles, so that information on the zeros provides further restrictions on the coupling constants.

Extreme-ultraviolet observations of nearby B stars - Constraints on hot circumstellar plasma

The extreme-ultraviolet telescope on the Apollo-Soyuz Test Project Mission observed several nearby stars of spectral type earlier than B3 in search of thermal emission from possible hot circumstellar plasma. The stars studied in the 45-185 and 114-185 A passbands of the instrument included Lambda Sco, Nu Sco, Beta CMa, Beta Cen, Sigma Sgr, and Alpha Pav. Diffuse emission around these stars in excess of about 1 billionth erg/sq cm/sec per sr/eV in the 45-185 A band and about 1 hundred-millionth erg/sq cm/sec per sr/eV in the 114-185 A band was not detected. The experimental data have been used to place upper limits on the emission measure of the plasma and the stellar-wind luminosity, using standard models. The data rule out the existence of sizable bubbles of hot plasma around any of the stars surveyed. In all cases the electron density in these regions, if they exist, may not exceed about 0.2 electron/cu cm.

Odd-parity rotational band structure inV48

A second odd-parity rotational band in the f/sub 7///sub 2/-shell nucleus /sup 48//sub 23/V/sub 25/, based on a 1099.1 keV state with K/sup ..pi../ = 4/sup -/, has been identified up to the 8/sup -/ member. Also, corrections are given for the previously reported 1/sup -/ band. These bands can be interpreted as the singlet and triplet couplings of the ..cap omega../sup ..pi../(Nn/sub Z/..lambda sigma..) = 3/2/sup +/(202 arrow-down) proton and 5/2/sup -/(312 up-arrow) neutron Nilsson orbitals, indicating prolate deformation.

Nature of the transition in non-linear spin-S Ising models (integer spin)

The spin-S Hamiltonian - beta H=K Sigma (i-, j)QS(Si)QS(Sj)+ Lambda Sigma kQS(Sk), where QS(y) is the polynomial in y of degree 2S whose eigenvalues are +or-1, is considered. Denoting the partition function by ZS(K, Lambda ), it is shown rigorously that ZS(K, Lambda )=(S(S+1))12N/Z12/(K, Lambda +C), 2C=ln(1+S-1), for all integer values of S.

Hyperon-Nucleon Interactions and ΛΣπ Coupling Constant

The charge-independence hypothesis and the time-reversal invariance are tested by making use of available information for the hyperon-- nucleon interactions. The LAMBDA SIGMA pi coupling constant is estimated from the real part of p-wave amplitude at low-energy SIGMA /sup -/p yields LAMBDA n reaction in comparison with the corresponding partial wave amplitude due to the one-pion-exchange non-local potential. The physical implication of the result is discussed in connection with analyses of previous authors on baryon- baryon interactions. (auth)

Vertex Functions of Baryon and Boson

The vertex functions of NN pi , LAMBDA NF, and LAMBDA SIGMA pi are investigated under the following assumptions: The elementary particles are p, n, LAMBDA , pi , K, and pi /sub o/, and the I-O-O symmetry holds in the high energy limit. The one-subtraction dispersion relation holds for the vertex function in which thr particles are elementary and the unsubtracted one holds when one of them is composite. Restricting ourselves to the two particles intermediate states, and assuming that the scattering amplitudes are known, the coupled dispersion relations for the vertex functions are obtained. Investigating their solutions, the following relations for the coupling constants are obtained: g/sub NN pi / approx equal g/sub LAMBDA NK/ approx equal 2g/ sub LAMBDA SIGMA pi /. (au th)

I=2S-Waveπ−πScattering Length

Using aphenomenological V + A coupling for the weak vertex LAMBDA yields + pi , a simple model of decays SIGMA yields + pi is constructed under the assumption of odd SIGMA LAMBDA parity. The model predicts that alpha /sub o/ approximately - sigma /sub LAMBDA / and that decay SIGMA /sub - / yields . n + pi /sup -/( SIGMA /sup +/ yields n + pi /sup +) is essentially pure s-wave (p-wave). (auth)

Scattering Matrix Approach to theΛ−πResonance

The pi LAMBDA resonance is studied in the energy range from m pi + m LAMBDA to mN + mK, using an effective-range theory. The effects of the three channels pi LAMBDA , pi LAMBDA , and KN are considered, taking I = 1 and assuming odd relative A SIGMA and AK parities. The scattering matrix is used to study the resonance properties of the system, and it is found that a resonance can exist, with (I,J) = (1,1/2/sup -/), that is consistent with experimental data. SIGMA LAMBDA even parity does not yield this (1,1/2-) resonance. (T.F.H.)

π−ΛResonance and the Sigma Hyperon

A resonance at 1385 plus or minus 15 Mev in the pi - LAMBDA system is inter preted as a SIGMA hyperon, composed for a pi and a LAMBDA with -65 Mev binding energy. The coupling between a pi - LAMBDA system and a K-bar-N (nucleon) system is considered in K/sup -/-p interactions, and an S-wave phase shift is derived for the pi - LAMBDA system. The phase angle is found under the restriction that the resonance be at 1385 Mev, and the results are discussed in terms of pi LAMBDA SIGMA relative spins, parities, and strangenesses. (T.F.H.)

OddΛΣParity and the Nature of theπΛΣCoupling

Experiments are indicated that support an odd LAMBDA SIGMA parity. It is shown that the scalar pi LAMBDA SIGMA coupling can be expressed as a function of the masses of pi , LAMBDA , and SIGMA . Under the asaumption of LAMBDA SIGMA odd panity, the pi LAMBDA SIGMA coupling results are clarified. (T.F.H.)

Influence of theΛπResonance on Correlations in the ReactionK−+d→Λ+π−+p

A 15-in. deuterium bubble chamber was exposed to a 450-Mev/c separated K/ sup -/ beam, and a group of events were examined corresponding to K/sup -/ + d yields LAMBDA + pi /sup -/ + p and K/sup -/ + d yields SIGMA /sup o/ + pi /sup -/ + p, SIGMA /sup o/ yields LAMBDA + gamma . The distribution of proto n and pion energies and their spectra are given. Two peaks appear in the pion spectram at 92 and 147 Mev; the 92-Mev peak agrees well with that calculated on the basis of SIGMA LAMBDA conversion and the zero-effective-range theory for the Swave interaction. The assumption of a LAMBDA pi resonance of total mass of 1382 Mev and half width of plus or minus 20 Mev gives a proton spectral peak near 30.5 Mev, in agreement with experiment. The contributions of direct production and conversion to the proton spectrum are also shown. The region of proton energies 5 to 20 Mev, where SIGMA LAMBDA conversion is negligible, is considered. Finally, the interactions are compared with the nonmesonic processes K/sup -/ + d yields SIGMA /sup -/ + p, SIGMA /sup o/ + n, or SIGMA + n.more » (D.L.C.)« less

Proposal for Determination ofΣΛRelative Parity from Chew and Low Analysis of Reactions of the FormA+B→C+D+E+⋯

The Chew and Low anslysis of reactions of the form A + B yields C + D + E + - - -, which makes use of the existence of a pole in the S matrix, is used to propose an experiment to determine the SIGMA LAMBDA relative parity and the coupling constant for the SIGMA LAMBDA pi interaction. It is found that the sign of the extrapolated cross section for the reaction SIGMA /sup +/ + d yields LAMBDA /sup 0/ + p + p is different for the two parity cases. Other applications of the Chew and Low method to strange particle reactions