Strangeness production in pA and AA collisions at 158 A GeV

LUCIAE, a hadronic and string cascade model and its corresponding event generator are used to analyse strangeness production singly and multiply in p-Pb and Pb-Pb collisions at 158 A GeV. Spectra of multiplicity and transverse mass for single (Λ, Λ) and multiple (Ξ-, Ξ-, Ω-, Ω-) strangeness are given. In LUCIAE model it suggests a physical mechanism, i.e. the dependence of the strange quark suppression factor on incident energy, projectile mass and centrality of colliding system might result in increase of yield of strange particles with increasing the above three parameters. Calculations from the model reconstruct well the WA97 experimental data: increase of yield of strange particles with increasing centrality and increase of strangeness enhancement with increasing number of strange quarks, in relativistic nucleus-nucleus collisions.     

Strangeness production in pA and AA collisions at 158A GeV

LUCIAE, a hadronic and string cascade model and its corresponding event generator are used to analyse strangeness production singly and multiply in p-Pb and Pb-Pb collisions at 158 A GeV. Spectra of multiplicity and transverse mass for single $(\Lambda ,\overline \Lambda )$ and multiple $(\Xi ^ - ,\overline {\Xi ^ - } ,\Omega ^ - ,\overline {\Omega ^ - } )$ strangeness are given. In LUCIAE model it suggests a physical mechanism, i.e. the dependence of the strange quark suppression factor on incident energy, projectile mass and centrality of colliding system might result in increase of yield of strange particles with increasing the above three parameters. Calculations from the model reconstruct well the WA97 experimental data: increase of yield of strange particles with increasing centrality and increase of strangeness enhancement with increasing number of strange quarks, in relativistic nucleus-nucleus collisions.     

Enhancement of φ meson production in p-p and Pb-Pb collisions at SPS energy

The φ meson yield, rapidity and transverse mass distributions in p-p and Pb-Pb collisions at 158 A GeV were studied by the hadron-string cascade model, LUCIAE. By adjusting the width parameter in q-q Gaussian like transverse momentum distribution in string fragmentation to fit the NA49 data ofφ meson transverse mass distribution in p-p collisions, the obtained φ meson rapidity distribution in p-p collisions, the rapidity and transverse mass distributions in Pb-Pb collisions, and theφ meson enhancement factor in Pb-Pb relative to p-p collisions were compatible with corresponding NA49 data, which might be attributed to the collective effect in gluon emission of string and the reduction of strange quark suppression mechanisms involved in the LUCIAE model.     

Enhancement of φ meson production in p-p and Pb-Pb collisions at SPS energy

The φ meson yield, rapidity and transverse mass distributions in p-p and Pb-Pb collisions at 158 A GeV were studied by the hadron-string cascade model, LUCIAE. By adjusting the width parameter in q Gaussian like transverse momentum distribution in string fragmentation to fit the NA49 data of φ meson transverse mass distribution in p-p collisions, the obtained φ meson rapidity distribution in p-p collisions, the rapidity and transverse mass distributions in Pb-Pb collisions, and the φ meson enhancement factor in Pb-Pb relative to p-p collisions were compatible with corresponding NA49 data, which might be attributed to the collective effect in gluon emission of string and the reduction of strange quark suppression mechanisms involved in the LUCIAE model     

Multiplicity distributions in a two-component branching process

Probability (multiplicity) distributions and those densities (KNO scaling functions) are investigated in a two-component (charged and neutral) branching process. It is shown that the two-component KNO scaling functions depend effectively on one variable in two typical cases. A formula for multiplicity correlation between two components (charged and neutral particles) is formulated. It is applied to the analysis of experimental data.     

Which sort of particles was emitted earlier during decay of highly excited nuclei?

Emission orders of light charged particles and Li fragments from highly excited fissioning nuclei in the reaction of⁴⁰Ar +¹⁹⁷Au atE _beam/A = 25 MeV have been studied by measuring difference velocity distributions of two correlated particles at small relative angles in coincidence with two fission fragments. By comparing the data with three-body trajectory calculations, it is found that high-velocity light particles (tritons and He particles) are emitted prior to high-velocity Li fragments but low-velocity light particles are emitted after low-velocity Li fragments. On the other hand, no preferential emission was observed among light particles, such as deuterons and tritons. Project supported by the National Natural Science Foundation of China (Grant Nos. 19675033 and 19575055) and the Science Foundation of the Chinese Academy of Sciences.     

A possible cosmic ray primary particle energy spectrum above 104 GeV and its astrophysical implications

A primary cosmic ray particle energy specturm of Galactic origin with a sharp cut-off at an energy per nucleon of 3 × 10⁴ GeV for protons and 5 × 10⁴ GeV for heavier particles and extending only upto energies ～ 10¹⁵ eV is deduced in part from the observed cosmic ray phenomena at the highest energies. It appears that the cut off is not due to the magnetic rigidity of the particles in the Galaxy but due to a cut off in or near the sources themselves. In particular, it is pointed out that Fermi type of acceleration is unlikely to be important in the production of energetic cosmic ray particles in the Galaxy. A pedestal in the energy spectrum from an extra Galactic component upto a maximum energy per nucleon ～ 10⁷ GeV with an upper limit of total energies ～ 10¹⁸ eV has been added.     

Nonstationary queues with Interrrupted Poisson arrivals and unreliable/repairable servers

A queueing model having a nonstationary Interrupted Poisson arrival process (IPP(t)),s time-dependent exponential unreliable/repairable servers and finite capacityc is introduced, and an approximation method for analysis of it is developed and tested. Approximations are developed for the time-dependent queue length moments and the system viewpoint waiting time distributions and moments. The approximation involves state-space partitioning and numerically integrating partial-moment differential equations (PMDEs). Surrogate distribution approximations (SDA's) are used to close the system of PMDEs. The approximations allow for analysis using only (s + 1)(s + 6) differential equations for the queue length moments rather than the 2(c + 1)(s +1) equations required by the classic method of numerically integrating the full set of Kolmogorov-forward equations. Effectively hours of cpu time are reduced to minutes for even modest capacity systems. Approximations for waiting time distributions and moments are developed.This research was partially funded by National Science Foundation grant ECS-8404409.     

Asymptotic expansions of the distributions of the latent roots and the latent vector of the Wishart and multivariate F matrices

Asymptotic expansions of the joint distributions of the latent roots of the Wishart matrix and multivariate F matrix are obtained for large degrees of freedom when the population latent roots have arbitrary multiplicity. Asymptotic expansions of the distributions of the latent vectors of the above matrices are also derived when the corresponding population root is simple. The effect of normalizations of the vector is examined.     

Atmospheric gamma-rays of 1–200 GeV over Hyderabad

Using a stack of hypersensitized nuclear emulsions, exposed under 10.2 g.cm^?2 of residual atmosphere over Hyderabad, India, gamma-rays of energy > 1 GeV have been studied. It is found that the observed differential energy spectrum can be best represented by two power law spectra, one for energies less than 30 GeV and the other for higher energies but with the same spectral index of 2.6; however the intensities at energies greater than 30 GeV are about three times higher than what would be expected from the extrapolation of the spectrum at lower enerjies. The implication of this observation has been examined. The neutral pion production spectrum over Hyderabad has been derived from the gamma-ray spectrum. Using this information the energy spectrum of atmospheric electrons has been deduced and a comparison made with the observed spectrum below the geomagnetic threshold energy over Hyderabad; therefrom an upper limit of 0.5 particles/(m².sr.sec.) has been deduced for the flux of re-entrant albedo electrons above 2 GeV.     

Multiple muon events observed underground

Observations are reported on events involving multiple penetrating particles recorded in a scintillator-neon flash tube telescope, at a depth of 1500 hg/cm² in the Kolar Gold Mines. From these, it is shown that: (1) the cross-section for nuclear interaction of muons of average energy ～200 GeV is ～ 6 × 10^?30 cm²/nucleon; (2) the decoherence curve for events involving two parallel muons is uniform over the range of distances from 0 to 2 metres; and (3) the angular distribution of double-parallel muons closely resembles that of single muons, implying that these two types of events are probably produced in the atmosphere in a similar manner.     

Oscillations of moments in high-energy nucleus-nucleus collisions

The definitions of density function and moment of multiplicity distribution are introduced, and the method of moment analysis in e⁺e^- and proton-proton (pp) interactions is extended into nucleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and calculate the values of H_q for charged particle multiplicity distributions, by which we study systematically the dependences of H_qon incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e⁺ e^-, pp and AA interactions, and the comparison and analysis are carried out between experimental data and QCD prediction. The latest results are given in this paper.     

Asymptotic safety of gravity and the Higgs-boson mass

If gravity is asymptotically safe, then the ultimate theory might be just the standard model (minimally supplemented by a few light particles to accommodate neutrino masses and oscillations, dark matter, and the baryon asymmetry of the Universe) plus gravity. If this is indeed the case, then the Higgs-boson mass can be predicted (m _H = m _min ≃ 130 GeV with an uncertainty of only a few GeV) or constrained to be in the interval m _min < m _H < m _max ≃ 174 GeV.     

Multiple periodic solutions for nonautonomous Hamiltonian systems

In this paper, by the use of minimax method, we obtain some existence and multiplicity theorems for periodic solutions of nonautonomous Hamiltonian systems with bounded nonlinearity of the type:¶ J [(x)\dot] + ?H(t, x) + e(t) = 0. J \dot x + \nabla H(t, x) + e(t) = 0.     

The limiting theorems for a random walk of two particles on the lattice ℤν

It is shown that the difference between the probability distributions of the particles positions at time t as t for homogeneous and inhomogeneous random walk of two particles on the lattice Z ³ has an order (>0 is a constant), if the distance |z| between the particles is large enough. As a consequence the integral limit theorem was proved in this case.partially supported by Russian Fund of Fundamental Research 93-011-1470.     

无穷区域上非线性向量方程初值问题的解的渐近性质

本文研究无穷域上的初值问题:其中x,f∈Em,y,g∈En,实的小参数ε>0,0≤t<+∞,在g_r(t)是非奇异的和其它适当的假设下,证明了存在一系列k+m*维流形{S_R(ε)}∈Em+n,使得如果(ξ(ε),η(ε))∈S_R(ε),方程(1.1)是正则退化的,并作出了解的R阶渐近展开式及其余项估计。     

Local spectral multiplicity of a linear operator with respect to a measure

Let T be a bounded linear operator in a separable Banach space X and let μ be a nonnegative measure in χ with compact support. A function m_T,μ is considered that is defined μ-a.e. and has nonnegative integers or +∞ as values. This function is called the local multiplicity of T with respect to the measure μ. This function has some natural properties, it is invariant under similarity and quasisimilarity; the local spectral multiplicity of a direct sum of operators equals the sum of local multiplicities, and so on. The definition is given in terms of the maximal diagonalization of the operator T. It is shown that this diagonalization is unique in the natural sense. A notion of a system of generalized eigenvectors, dual to the notion of diagonalization, is discussed. Some examples of evaluation of the local spectral multiplicity function are given. Bibliography:10 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 222, 1995, pp. 293–306.