Short pulse physics of quantum well structures

This paper reports some recent results of time-resolved studies of the carrier dynamics in GaAs/GaAlAs quantum well structures with picosecond and subpicosecond time resolution. These experiments have provided insight into carrier trapping, energy relaxation, and carrier recombination processes. Carrier trapping into the quantum well layers is very efficient and determines the decay of the GaAlAs luminescence even for 1 μm thick cladding layers. Carrier recombination is enhanced particularly at low temperatures. This effect has been attributed to the increased overlap of electron and hole (exciton) wavefunctions in the quasi-two-dimensional carrier system.     

Relativistic physics from quantum theory

An investigation of the invariance of quantum theory under the complex group reveals a natural origin of relativistic physics from quantum theory. Once such an origin of relativity is accepted, quantum limitations on the applicability of standard relativistic theory also become evident.     

Quark confinement physics from quantum chromodynamics

We show the construction of the dual superconducting theory for the confinement mechanism from QCD in the maximally abelian (MA) gauge using the lattice QCD Monte Carlo simulation. We find that essence of infrared abelian dominance is naturally understood with the off-diagonal gluon mass m_off ≈- 1.2GeV induced by the MA gauge fixing. In the MA gauge, the off-diagonal gluon amplitude is forced to be small, and the off-diagonal gluon phase tends to be random. As the mathematical origin of abelian dominance for confinement, we demonstrate that the strong randomness of the off-diagonal gluon phase leads to abelian dominance for the string tension. In the MA gauge, there appears the macroscopic network of the monopole world-line covering the whole system. We investigate the monopole-current system in the MA gauge by analyzing the dual gluon field B_μ. We evaluate the dual gluon mas as m_B = 0.4 0.5GeV in the infrared region, which is the lattice-QCD evidence of the dual Higgs mechanism by monopole condensation. Owing to infrared abelian dominance and infrared monopole condensation, QCD in the MA gauge is describable with the dual Ginzburg-Landau theory.     

Tau physics results from BABAR

Since 1999, the BABAR collaboration has accumulated and studied large samples of tau lepton pairs. The main physics results are reported.     

Tau physics results from BABAR

Since 1999, the BABAR collaboration has accumulated and studied large samples of tau lepton pairs. The main physics results are reported.     

Some remarks on effects,operations, and unsharp measurements

A brief survey is given of some important features of a generalized quantum mechanics and its measurement theory, together with an overview of papers and monographs representative of the rather new research field dealing with these subjects.     

Recent results on heavy-ion physics from the SPS

The CERN SPS heavy-ion physics program was recently given an important and fresh impetus with the running of the NA60 dimuon experiment, which probed indium-indium collisions at 158 GeV per incident nucleon (in 2003), as well as proton-nucleus collisions at 158 and 400 GeV (essentially in 2004). Several interesting physics results have been obtained and were recently presented by NA60. They address such varied physics topics as the search for in-medium modifications on the ρ short-lived vector meson (which could be related to the restoration of chiral symmetry, spontaneously broken in the hadronic world), the understanding of the “anomalous” J/ψ suppression (expected to be a signature of quark-gluon deconfinement), the search for thermal dimuons (presumably radiated from a thermal system, maybe composed of deconfined quarks and gluons — the “quark-gluon plasma”), the understanding of the enhancement of θ production in heavy-ion collisions, etc. These topics were previously studied by other SPS experiments, and very interesting observations were made, but serious doubts remained concerning the interpretation of those earlier results. It is remarkable that one single experiment, NA60, is able to provide high-quality information on each of these many topics, potentially triggering a very significant step forward in our understanding of “quark-matter physics”.In this paper, after a general introduction, I describe the NA60 apparatus, the data taking conditions, and the main steps in the data reconstruction procedure. I then give some information on the muon track matching and background subtraction procedures. In the remaining sections I review some of the results presently available from the on-going physics analyses, in what concerns the studies of low mass and intermediate mass dimuon production, and J/ψ suppression, in proton-nucleus and indium-indium collisions. These new (and still preliminary) results are placed in perspective, by recalling the findings of previous experiments.     

New Lie-algebraic structures in nonlinear problems of quantum optics and laser physics

New Lie-algebraic structures (polynomial deformations of Lie algebras) are revealed in some problems of quantum optics and laser physics. Specifically, deformations of oscillator algebras due to extensions of unitary algebras by their symmetric and skew-symmetric tensors are shown to be algebras of dynamic symmetry (ADS) in models of n-photon processes with internal symmetries. Similarly, deformed algebras su_d(2) are found as ADS in the context of generalized Dicke models and frequency conversion models. We also briefly discuss some possible schemes of employing the results to solving physical problems.Based on materials of the Second International Wigner Symposium (Goslar, Germany, July 16–20, 1991) and the International Workshop Squeezing, Groups, and Quantum Mechanics (Baku, Azerbaijan, September 16–20, 1991).Lebedev Physics Institute, Leninsky prospect 53, Moscow 117924, Russia. Published as Preprint No. 138 (1991) of the Lebedev Physics Institute (in English).     

Some physics highlights from the EUROBALL spectrometer

Exotic, neutron-rich proton-induced spallation products of ²³²Th and ²³⁸U obtained from the PS Booster ISOLDE facility have been investigated by - , - coincidence and spectrum-multiscaling measurements. A new method for the reduction of isobaric contamination enabled to study the unknown region beyond ²⁰⁸Pb for the decay chain A = 217. A new isotope ²¹⁷Bi with a half-life of s was discovered and its -decay studied. For the first time, a half-life value of s for the -decay of ²¹⁷Po was measured.Received: 3 March 2003, Revised: 13 May 2003, Published online: 30 September 2003PACS: 23.20.Lv transitions and level energies - 23.60.+e decay - 27.80.+w 190 A 219 - 29.30.Kv X- and -ray spectroscopyV. Fedoseyev: Present address: ISOLDE, CERN-PPE, CH-1211, Geneva 23, Switzerland.M. Górska: Present address: GSI, Darmstadt, D-64220, Germany.M. Huhta: Present address: Nokia, Tampere, Finland.     

Some relationships between representation systems and physics. II: Non-relativistic quantum theory

Using Bunge's procedures, non-relativistic quantum mechanics is discussed. It is shown that if a certain carefully defined idea of determinism is included in the presentation, operators which are not Hermitian need to be used to describe physical processes. An absolute time scale is suggested.     

Recent KLOE results on hadron physics

The KLOE experiment at the Frascati e ⁺ e ^- collider DAFNE has completed this year its data taking. An integrated luminosity of 2.7fb^-1 has been collected mostly at the φ-resonance peak. A wide experimental program is in progress. The detection of φ radiative decays allows to study the properties of the lowest-mass scalar and pseudoscalar mesons and to obtain information on their structure. The main results are reviewed together with the prospects for low-energy e ⁺ e ^- physics at Frascati.     

Causality in local quantum field theory: Some general results

General asymptotic causality properties of chronologicalN-point functions and, in massive theories, ofN-particle collision amplitudes, are derived from locality and the spectral condition. Results include specified rates of exponential fall-off, with simple and direct physical content, for large non-causal separations of points or particles in Minkowski space-time depending on values of the energy-momenta and on the mass spectrum. Relevant mathematical results on rates of exponential fall-off of generalized Fourier transforms outside their microsupports are given.Laboratoire de la Direction des Sciences de la Matière du Commissariat à l'Energie Atomique     

Field emission from quantum size GaN structures

Whisker structures and quantum dots fabricated by photoelectrochemical (PEC) etching of undoped and doped metalorganic chemical vapor deposition (MOCVD)-grown GaN (2×10¹⁷ or 3×10¹⁸ cm⁻³) are investigated in relation with their field-emission characteristics. Different surface morphologies, corresponding to different etching time and photocurrent, results in different field-emission characteristics with low turn-on voltage down to 4 V/μm and the appearance of quantum-size effect in the I–V curves.     

Three short distance structures from quantum algebras

We review known and we present new results on three types of short distance structures of observables which typically appear in studies of quantum group related algebras. In particular, one of the short distance structures is shown to suggest a new mechanism for the introduction of internal symmetries. Presented at the 6th International Colloquium on Quantum Groups: “Quantum Groups and Integrable Systems”, Prague, 19–21 June 1997.     

Astrophysical structures from primordial quantum black holes

The characteristic sizes of astrophysical structures, up to the whole observed Universe, can be recovered, in principle, assuming that gravity is the overall interaction assembling systems starting from microscopic scales, whose order of magnitude is ruled by the Planck length and the related Compton wavelength. This result agrees with the absence of screening mechanisms for the gravitational interaction and could be connected to the presence of Yukawa corrections in the Newtonian potential which introduce typical interaction lengths. This result directly comes out from quantization of primordial black holes and then characteristic interaction lengths directly emerge from quantum field theory.     

International symposium on fundamental problems in quantum physics

Announcement

International symposium on fundamental problems in quantum physics     

Some results on the quantum dynamics of a particle in a Markovian potential

We consider the quantum dynamics of a particle in a time dependent potentialV(t), assuming it to be a Markovian random function of time. We derive a formula for the density matrix at timet averaged over the realisations of the potential. We then obtain a kind of RAGE theorem for the time evolution of compact observables, and some information on the phase space behaviour of the system.     

Recent results in high p T physics from CDF

The European Physical Journal C - We present the most recent high p T results from the CDF experiment using $p\overline{p}$ collisions at $\sqrt{s}=1.96~$ TeV produced at the Tevatron Collider at...