Remarks on the charged multiplicity of hadronic Z0(91) decays

The charged multiplicity distribution of hadronic decays of Z ⁰ from LEP and those of inclusive $e^{+}+e^{-}?ghtarrow h{?erline h} at E_{? cm}=14 {? to} 60 {? GeV}$ at E _cm = 14 to 61 GeV are analyzed using a Poisson-type distribution for photon statistics, due to Scully-Lamb. Its two parameters are expressed in terms of 〈n〉 and f ₂ = 〈n(n ? 1)〉 ? 〈n〉² of the data in order to perform no-free-parameter fits. It is found that f₂ behaves like $E_{? cm}^{a}$ with a = 2.01 ± 0.11, whereas C ₂ = 〈n ²〉/〈n〉² ～ E _cm with ΔC ₂/ΔE _cm = (1.81 ± 0.14)·10^?3.     

Antibunching,sub-poissonian photon statistics and finite bandwidth effects in resonance fluorescence

It is demonstrated that, although the fluorescent photons from a driven two-level atom always exhibit antibunching, they need not obey sub-poissonian statistics. The maximum sub-poissonian excursion of the normalized second factorial moment (〈(Δn)²〉 ? 〈n〉)/〈n〉 occurs in the transient regime where it can approach the value -1. Effect s of finite bandwidth of excitation on photon statistics are also investigated and it is shown that the photon number distribution may be narrower with finite bandwidth excitation than with coherent excitation.     

New bounds for dilepton production from heavy neutral leptons

Bounds on 〈E_?ⁿ〉/〈E₊ⁿ〈, 〉E₊E_?〈/〉E₂²〈 and 〈E₊E_?〉/〈E₊〉〈E_?〉 are direved for the processes ν_μN → μ^?μ⁺(e⁺) + X and μN → μ^?μ⁺ + X if dileptons are mediated by a $\text{spin}\text{-}\text{1}\text{2}$ heavy neutral lepton L₀. The bounds are shown to be independent of the production mechanism and mass of L₀. Useful conditional bounds are obtained relating the bounded quantities, which give information about the structure of the weak current responsible for L₀ decay.     

General features ofK + d interactions at 70 GeV/c

We have studied 70 GeV/cK ⁺ d interactions from about 10 K events. The inelastic cross-section for three or more prongs is found to be (28.9±0.4) mb. From odd-and even-prong topologies we have extracted topological break-up ofK ⁺ n interactions by taking into account spectator corrections, rescattering effects and Glauber screening. The rescattering fraction is found to be 0.06±0.01 which is substantially different from pion and proton interactions. Combining ourK ⁺ n data with other existing π^± n andp ^±n we find〈n _ch 〉 ^ph ?〈n _ch 〉 ^hn =0.33±0.04 andD/〈n _ch 〉=0.529±0.003.     

Uncorrelated-jet-model predictions for the multiplicity distribution of π− mesons produced in high-energy annihilations p¯p → pions

The uncorrelated jet model is used to obtain a grand partition function for the pions produced in the process $\overline{p}p$ → pions. The grand partition function is evaluated asymptotically for large energies. It is used to relate the correlation parameter f₂ = 〈n_?²〉 ? 〈n_?〉² ? 〈n_?〉 to the average multiplicity of negative pions 〈n_?〉. The results are consistent with the presently available experimental data, though data at higher energies are necessary to draw physically interesting conclusions.     

π0 Multiplicities in π+;p interactions at 10.5 GeVc

Measurement of the π⁰ multiplicity cross sections are reported for n₀ ? 6, where n⁰ is the number of produced π⁰ particles, and for N ? 8, where N is the number of charged particles. The inclusive π⁰ cross section is 29 ± 3 mb. Values for the correlation parameters, 〈n₀〉 and 〈n₀(n₀ ? 1)〉², are also presented.     

Multiplicity distributions in e+e− annihilations at petra energies

Measurements of the charged multiplicities for hadron production in e⁺e^? annihilation in the center of mass energy range 9–32 GeV have been made. The average charged multiplicity has an energy dependence much stronger than ln s and similar to that reported for pp collisions. Quantitative differences are observed in the magnitude of both the average multiplicity 〈n_ch〉 and the dispersion D_ch for e⁺e^? and pp interactions at the same center of mass energy. 〈n_ch〉 and the ratio 〈n_ch/D_ch in e⁺e^? annihilations are significantly larger than in pp collisions and are found to be in overall agreement with QCD predictions. KNO scaling is seen to be satisfied.     

Characteristics of π−-meson multiplicity distributions in central collisions of12C and16O with nuclei at a momentum of 4.5 GeV/c per incident nucleon

Multiplicities of π^?-mesons from central collisions of¹²C and¹⁶O(4.5 GeV/c/n momentum) with several target nuclei were studied in a streamer chamber experiment. The parameter η=(〈n _? ² 〉?〈n_?〉²)/〈n_?〉 was determined for several samples of events characterized by different values of Θ _ch — the “vetoangle” for emission of the projectile charged fragments. The value of η is shown to decrease when the projectile mass number increases from 12 to 16 and to decrease significantly when Θ _ch increases from 0° to 4°, whereas it remains nearly constant when Θ _ch increases further to 14°. The results are compared with predictions of some theoretical models.     

Charged multiplicity distributions in pd and π+d interactions at 195 GeV/c

Topological inelastic cross-sections and average multiplicities for pd and π⁺d interactions at 195 GeV/c, are obtained from an exposure of the NAL 30″ proportional wire chamber-bubble chamber hybrid system to a positive π⁺/p beam. We find that 〈n_c〉_pn = 7.67 ± 0.25, and 〈n_c〉_π⁺n = 7.56 ± 0.30, yielding a negative multiplicity difference between pn and pp of 0.50 ± 0.14, and that σ_n(pp) is approximattely interleaved between σ_n?1(pn).     

n-shell Thomas-Fermi model: Coulomb atom

A simple expression for the electron density of then-shell of the Coulomb atom with the nuclear charge Zρ _n(r)=Z ³ π ^?2 n ^?3(2Z ^?1 r ^?1?n ^?2)^1/2 is found in the semi-classical approximation. It is used for the asymptotic estimation of averages 〈r ^a 〉 (?2<a<∞). An explicit dependence of the leading oscillatory contribution to 〈r ^a 〉 due to angular moments on the electron number is also obtained.     

Cosmic ray results on the A dependence of multiplicity and angular distributions in proton nuclear interactions above 100 GeV

A calorimeter-spark chamber system was used to collect data on several hundred proton-nucleus interactions above 100 GeV using targets of C, Al, Fe, Sn and Pb. The average charged prong multiplicity is found to depend on atomic mass number as 〈n_c〉 = 〈n_c〉(p-p)A^x where x = 0.129 ± 0.004, with the dominant increase in multiplicity occuring in the backward (p-p c.m.) hemisphere. The value of x shows no significant energy dependence.     

Diffusive capture processes for information search

We show how effectively the diffusive capture processes (DCP) on complex networks can be applied to information search in the networks. Numerical simulations show that our method generates only 2% of traffic compared with the most popular flooding-based query-packet-forwarding (FB) algorithm. We find that the average searching time, 〈T〉, of the our model is more scalable than another well known n-random walker model and comparable to the FB algorithm both on real Gnutella network and scale-free networks with γ=2.4. We also discuss the possible relationship between 〈T〉 and 〈k²〉, the second moment of the degree distribution of the networks.     

On the charge structure of high-energy multiple production

Correlations between neutral and charged particles produced in high-energy collisions are studied. The associated average multiplicity 〈n₀〉_n and the associated moment (f₂⁰⁰) are expressed in terms of the Mueller moments. An isospin analysis of the pion - pion correlations is performed with the help of Mueller-Regge techniques. From this analysis, the slope of 〈n₀〉_n? is predicted to be asymptotically about 0.75. This asymptotic limit should be approached already at ISR energies. Finally, predictions are given for the associated moment (f₂⁰⁰)_n?, and the importance of the measurements of this quantity is emphasized.     

Second moment of multiple-quantum NMR and a time-dependent growth of the number of multispin correlations in solids

The time evolution of multispin correlations (the growth of the number of correlated spins as a function of time) can be observed directly using the multiple-quantum nuclear magnetic resonance spectroscopy of solids. A quantity related to this number, namely, the second moment 〈n ²(t)〉 of the intensity distribution of coherences of different orders in the multiple-quantum spectrum can be calculated using the theory proposed in this work. An approach to the calculation of the four-spin time correlation function through which this moment is expressed is developed. The main sequences of contributions in the expansion of this function into a time power series are summed using the approximation of a large number of neighbors both for systems with a secular dipole-dipole interaction and for systems with a nonsecular effective interaction. An exponential dependence of 〈n ²(t)〉 is obtained. The value of 〈n ²(t)〉 is additionally calculated using an expansion in terms of orthogonal operators for three model examples corresponding to different limiting realizations of spin systems. It is shown that the results of the microscopic theory at least qualitatively agree with both the results obtained for model examples and experimental results obtained recently for adamantane.     

Is KNO scaling proved or postulated?

Assuming Feynman's scaling law, Koba, Nielson and Olesen had shown that as s → ∞, (i) 〈n^q〉/〈n〉^q → d_q where d_q is independent of s and $\text{(ii)}\text{σ}{}_{\mathrm{n}}\text{(s)/σ}{}^{\mathrm{(s)}}{}_{\mathrm{<mtext>incl</mtext>}}\text{→ (}\text{1}\text{〈n〉)}\text{Ψ(n/〈n〉)}$. The derivation of the latter result is, however, not rigorous and it does not follow, as a necessary consequence, from the scaling law.     

The missing mass squared dependence of the average charged particle multiplicity in the reaction K+p → KoX++ from 5–16 GeV/c

The average charged particle multiplicity, 〈n_ch(M_X²)〉, in the reaction K⁺p→K^oX⁺⁺ is studied as a function of the mass squared, M_X², of the recoil system X and also as a function of the K^o transverse momentum, p_T, at incident momenta of 5.0, 8.2 and 16.0 GeV/c. The complete data samples yield distributions which are not independent of c.m. energy squared, s, They exhibit a linear dependence on log (M_X²_X/M_o²)[M_o²=1 GeV²] with a change in slope occurring for M_X²≈s/2, and do not agree with the corresponding distributions of 〈n_ch〉 as a function of s for K⁺ p inelastic scattering. Sub-samples of the data for which K^o production via beam fragmentation, central production and target fragmentation are expected to be the dominant mechanisms show that, within error, the distribution of 〈n_ch(M_X²)〉 versus M_X² is independent of incident momentum for each sub-sample separately. In particular in the beam fragmentation region the 〈n_ch(M_X²)〉 versus M_X² distribution agrees rather well with that of 〈n_ch〉 versus s for inelastic K⁺p interactions. The latter result agrees with recent results on the reactions pp → pX and π^?p → pX in the NAL energy range. Evidence is presented for the presence of different production mechanisms in these separate regions.     

Dirac-Fock studies of some electronic properties of actinide ions

Results of accurate Dirac-Fock studies of some U, Np, Pu and Am ions are reported; these include one-electron eigen-values, spin-orbit splittings, 〈rⁿ〉 values for the 5f electrons, Slater F^k and G^k integrals, Mössbauer isomer shift electronic densities and the 〈j_i〉 integrals needed for neutron magnetic form factors.     

Neutral-pion correlations. Test of production models

The observed increase of the average number of neutral pions, 〈n_o〉_n?, as a function of the number of charged pions produced in high-energy experiments, can be accounted for by several theoretical models. We analyze the basic trends of the models and find that in the region where 〈n_o〉_n? increases, the π⁰ multiplicity distribution is mainly determined by the isospin properties of the pion clusters and is insensitive to the overall multiplicity distribution. We calculate the values of f_2,n?⁰, the correlation parameter of two π⁰ for a given number of π^?, and show how its measurement can provide a clear test of the different production models.     

Franck-Condon factors and R-centroids for the BΣ → AΠ band system of CN

Franck-Condon factors and R-centroids for the transition from the B²Σ electronic state of CN to the A²Π state have been calculated. The validity of the Morse potential energy function for this system has been studied by using the calculated values of α_e. Also, the ratios 〈rⁿ〉/〈rⁿ⁻¹〉 have been obtained to check the applicabili ty of the R-centroid approximation.