Test of quantum mechanics by neutron interferometry

Measurements of the π⁰ and direct photon nuclear modification factors in p+p and A+A collisions in the PHENIX experiment at RHIC will be reviewed and recent results at  GeV will be presented. Using for the first time the p+p reference measured in the same experiment instead of averaging world data the π⁰ suppression turns out to be almost as large at  GeV as at  GeV, implying gluon densities dN^g/dy>800. Possible origins of photon suppression at high p_T in  GeV are discussed in light of the new results on photon R_AA at  GeV.     

Precision mass measurements of radioactive nuclei at JYFLTRAP

The Penning trap mass spectrometer JYFLTRAP was used to measure the atomic masses of radioactive nuclei with an uncertainty better than 10 keV. The atomic masses of the neutron-deficient nuclei around the line were measured to improve the understanding of the rp-process path and the SbSnTe cycle. Furthermore, the masses of the neutron-rich gallium ( ) to palladium ( ) nuclei have been measured. The physics impacts on the nuclear structure and the r-process paths are reviewed. A better understanding of the nuclear deformation is presented by studying the pairing energy around .     

What has a symmetry violation in particle physics to do with non-locality?

Particle physics has become an interesting testing ground for fundamental questions of quantum mechanics (QM). The massive meson-antimeson systems are specially suitable as they offer a unique laboratory to test various aspects of particle physics ( violation, violation, ...) as well to test the foundations of QM (local realistic theories versus QM, Bell inequalities, decoherence effects, quantum marking and erasure concepts, ...). We focus here on a surprising connection between the violation of a symmetry in particle physics –the symmetry ( =charge conjugation, =parity)– and non-locality. This is achieved via Bell inequalities which discriminate between local realistic theories and QM. Further we present a decoherence model which can be tested by accelerator experiments at the DAΦNE (Italy) and at the KEK-B machine (Japan). We show that there is a simple connection between a decoherence parameter and different measures of entanglement, i.e., entanglement of formation and concurrence. In this way the very basic mathematical and theoretical concepts about entanglement can be confronted directly with experiments. Similar decoherence models can also be tested for entangled photon systems and single neutrons in an interferometer.     

Hyperfine structure and isotope shift study in singly ionized lead

Hyperfine structure and isotope shifts in five optical transitions: 424.5 nm ( – ), 537.2 nm ( – ), 554.5 nm ( – ), 560.9 nm ( – ) and 666.0 nm ( – ) of Pb  II have been measured. As a light source the discharge tube was used. The hyperfine structure measurements were performed using metallic isotope ²⁰⁷Pb. For isotope shifts measurements natural lead was used. The high resolution spectral apparatus consisted of a silver coated Fabry-Perot etalon and a grating spectrograph combined with a CCD camera used as a detector. In the analysis of the spectra a computer simulation technique was used. The hyperfine structure observations yielded the splitting constants A for seven levels of Pb II. The isotope shift studies enabled to separate the mass and the field shifts and to determine values of changes of the mean square nuclear charge radii.     

Semihard scattering unraveled from collective flow at the SPS

A study of elliptic flow and two-particle azimuthal correlations of charged particles ( GeV/c) and high- pions ( GeV/c) in Pb + Au collisions at 158A GeV/c, close to midrapidity, is presented. Elliptic flow (v ₂) rises linearly with to a value of about 10 at 2 GeV/c. Beyond 1.5 GeV/c, the slope decreases and possibly indicates a v ₂ saturation at high . Two-pion azimuthal anisotropies for 1.2 GeV/c exceed the v ₂ values by about 60 in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the near-side peak remains constant with centrality 0.23 0.03 rad, as expected for fragmentation, the away-side peak experiences broadening and disappears in central collisions. Arrival of the final proofs: 30 June 2005 PACS: 25.75.Ld, 25.75.Gz     

Multijet production in neutral current deep inelastic scattering at HERA and determination of $\alpha_s$

Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities . The data were taken at the ep collider HERA with centre-of-mass energy using the ZEUS detector and correspond to an integrated luminosity of . Jets were identified in the Breit frame using the k_T cluster algorithm in the longitudinally invariant inclusive mode. Measurements of differential dijet and trijet cross sections are presented as functions of jet transverse energy ( ), pseudorapidity ( ) and Q² with and . Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant , determined from the ratio of the trijet to dijet cross sections, is . Received: 1 April 2005, Revised: 28 June 2005, Published online: 30 August 2005     

Five-Body Calculation of Resonance and Scattering States of the uudd\bar{s} System

The scattering problem of the system, in the standard non-relativistic quark model of Isgur-Karl, is solved for the first time, by treating the large five-body model space, including the NK scattering channel, accurately with the Gaussian expansion method and the Kohn-type coupled-channel variational method. The calculated NK scattering phase shift shows no resonance in the energy region of the reported pentaquark Θ⁺(1540) that is, at 0–500 MeV above the NK threshold (1.4–1.9 GeV in mass). The phase shift does show two resonances just above 500 MeV: a broad ⁺ resonance with a width of Γ ∼ 110 MeV located at ∼ 520 MeV (∼ 2.0 GeV in mass) and a sharp ⁻ resonance with Γ = 0.12 MeV at 540 MeV.     

Cluster structure of <Superscript>16</Superscript>O

A folding potential describing the -scattering on ¹⁶O over a broad energy range 25.8-146.0 MeV is constructed on the basis of -like cluster and unclustered-nucleon configurations of ¹⁶O. The resulting potential does not need any renormalization to fit the angular distribution of elastic cross-sections. The effects of the repulsive part of - and -nucleon interactions are investigated. The analysis suggests that both the - repulsive potential and the unclustered nucleonic configuration in the target are important to describe the scattering data over a broad range of incident energies. The root-mean-square radius for the ¹⁶O nucleus is deduced.Received: 5 December 2002, Published online: 9 October 2003PACS: 25.55.Ci Elastic and inelastic scattering - 24.10.Ht Optical and diffraction models - 21.60.Gx Cluster models     

Di-jet production in photon-photon collisionsat $\sqrt{s_{\protect\bf\mathrm{ee}}}$ from 189 to 209 GeV

Di-jet production is studied in collisions of quasi-real photons at e ⁺ e^- centre-of-mass energies from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive -clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy of the two leading jets, and as a function of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, , for different regions of . Angular distributions in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of and is presented, where is the jet pseudo-rapidity. Different regions of the - -space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.Received: 20 December 2002, Published online: 17 October 2003     

Collectivity in neutron-deficient Pb and Po nuclei

Lifetimes of low-lying yrast states in ¹⁸⁶Pb and ¹⁹⁴Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in ¹⁸⁸Pb up to the 8⁺ state were carried out using the recoil gating method. The deformation parameters and for the prolate (^186,188Pb) and the oblate (¹⁹⁴Po) bands, respectively, have been extracted from the measured lifetimes. 27.70.+q–     

Transition energies of atomic lawrencium

Transition energies of the superheavy element lawrencium, including the ionization potential, excitation energies and electron affinities, are calculated by the intermediate Hamiltonian coupled cluster method. A large basis set (37s31p26d21f16g11h6i) is used, as well as an extensive P space (6s5p4d2f1g). The outer 43 electrons are correlated. Accuracy is monitored by applying the same approach to lutetium, the lighter homologue of Lr, and comparing with experimentally known energies. QED corrections are included. The main goal is to predict excitation energies, in anticipation of planned spectroscopy of Lr. The ground state of Lr is , unlike the of Lu. Predicted Lr excitations with large transition moments in the prime range for the planned experiment, 20 000–30 000 cm^-1, are 7p→8s at 20 100 cm^-1 and 7p→7d at 28 100 cm^-1. The average absolute error of 20 excitation energies of Lu is 423 cm ^-1, and the error limits for Lr are put at 700 cm^-1. The two electron affinities measured recently for Lu are reproduced within 55 cm^-1, and a third bound state of Lu^- is predicted.     

Exclusive semileptonic rare decays $B \to K^{(*)} l^ + l^-$ in a SUSY SO(10) GUT

In the SUSY SO(10) GUT context, we study the exclusive processes . Using the Wilson coefficients of the relevant operators including the new operators which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like the invariant mass spectrum (IMS), lepton pair forward-backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients , among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA, , and of decay, which are expected to be measured in B factories, the deviation of in can reach 0.1 from SM, which could be seen in B factories, and the average of the normal polarization can reach several percent for and it is 0.05 or so for , which could be measured in the future super B factories and provide useful information to probe new physics and discriminate different models.Received: 30 October 2004, Published online: 9 March 2005     

e<Superscript> + </Superscript>e<Superscript>-</Superscript>-pair production in Pb-Au collisions at 158 GeV per nucleon

We present the combined results on electron-pair production in 158 GeV/n Pb-Au ( = 17.2 GeV) collisions taken at the CERN SPS in 1995 and 1996, and give a detailed account of the data analysis. The enhancement over the reference of neutral meson decays amounts to a factor of 2.31 for semi-central collisions (28 ) when yields are integrated over m > 200 MeV/c² in invariant mass. The measured yield, its stronger-than-linear scaling with , and the dominance of low pair p_t strongly suggest an interpretation as thermal radiation from pion annihilation in the hadronic fireball. The shape of the excess centring at 500 MeV/c², however, cannot be described without strong medium modifications of the meson. The results are put into perspective by comparison to predictions from Brown-Rho scaling governed by chiral symmetry restoration, and from the spectral-function many-body treatment in which the approach to the phase boundary is less explicit.Received: 2 March 2005, Published online: 8 June 2005     

An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment

The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e ⁺ and e^- beams, together with differential cross-section data on inclusive jet production in e ⁺ p scattering and dijet production in scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet-production data constrains the gluon and allows an accurate extraction of at NLO; An additional uncertainty from the choice of scales is estimated as . This is the first extraction of from HERA data alone.     

Liquid crystalline optical components for application in optical sensing

Manufacturing process of Wollaston prisms using ZLI-1957 Liquid Crystal (LC) mixture and waveplates from RMS03-001 Liquid Crystalline Polymer (LCP) is presented. The Wollaston prism presented in the paper has the splitting angle of 0.37 mrad, and can be used in optical setups where very straight fringes are not required. Produced LCP waveplates exhibit retardation from 175.3 nm to 238.6 nm at the wavelength of 622 nm and show local retardation variations of .     

Aggregate size distributions in migration driven growth models

The kinetics of aggregate growth through reversible migrations between any two aggregates is studied. We propose a simple model with the symmetrical migration rate kernel at which the monomers migrate from the aggregates of size k to those of size j. The results show that for the case, the aggregate size distribution approaches a conventional scaling form; moreover, the typical aggregate size grows as in the case and as in the case. We also investigate another simple model with the asymmetrical rate kernel ( ), which exhibits some scaling properties quite different from the symmetrical one. The aggregate size distribution satisfies the conventional scaling form only in the case of and , and the typical aggregate size grows as .Received: 14 October 2003, Published online: 23 December 2003PACS: 82.20.-w Chemical kinetics and dynamics - 68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation - 89.75.Da Systems obeying scaling laws     

Low mass dimuon production in proton-nucleus collisions with the NA60 apparatus

During the June 2002 run NA60 collected around 600 000 dimuon triggers in proton-nucleus collisions at 400 GeV. We show that the collected dimuon mass spectra can be understood in terms of known sources. The specific target setup, consisting of Beryllium, Indium and Lead targets, simultaneously exposed to the beam, allowed us to study the nuclear dependence of the production cross-section of the and resonances. The elementary nucleon-nucleon production cross-sections at 400 GeV for the , and mesons are also presented. By using the -Dalitz decay, dominating the mass range below 450 MeV, we, furthermore, extracted the production cross-section and its nuclear dependence. The results are discussed in the framework of previous measurements, mostly obtained in different decay channels, performed by NA27, HELIOS-1 and CERES-TAPS. Arrival of the final proofs: 1 July 2005 PACS: 25.75.Dw, 25.75.Nq     

Lifetime vibrational interference during the NO 1s-1π* resonant excitation studied by the NO+(A 1Π → X 1Σ+) fluorescence

Dispersed fluorescence from fragments formed after the de-excitation of the 1s^-1π^* resonances of N^*O and NO^* has been measured in the spectral range of 118–142 nm. This range is dominated by lines of atomic nitrogen and oxygen fragments and by the bands in the NO⁺ ion which result from the participator Auger decay of the 1s^-1π^* resonances. Ab-initio calculations of the transition probabilities between vibrational levels during the reaction NO N^*O ⇒ NO were used to explain the observed intensity dependence for the fluorescence bands on the exciting-photon energy across the resonances and on both v^′ and v^′′ vibrational quantum numbers. The multiplet structure of the 1s^-1π^* resonance and lifetime vibrational interference explain the observed exciting-photon energy dependence of the fluorescence intensity. A strong spin-orbit coupling between singlet and triplet states of NO⁺ is proposed to reduce additional cascade population of the state via radiative transitions from the and states and to explain remaining differences between measured and calculated integral fluorescence intensities.     

First structure information on the exotic 149 La from the $\beta^-$-decay of 149 Ba

The -decay of ¹⁴⁹Ba to ¹⁴⁹La has been investigated by means of - and X-ray spectroscopy, and a partial level scheme of ¹⁴⁹La has been constructed for the first time. It includes thirteen -rays and ten excited states. The exotic ¹⁴⁹La is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the ¹⁴⁹La ground state. The deformed ground state was found at 0.23, 0 and 0.12.Received: 18 July 2003, Revised: 12 January 2004, Published online: 26 May 2004PACS: 27.60. + j - 29.30.Kv X- and -ray spectroscopy     

Mo6S6 nanowires: structural, mechanical and electronic properties

The properties of nanowires were investigated with ab initio calculations based on the density-functional theory. The molecules build weakly coupled one-dimensional chains, like and Mo₆S_9-xI_x, and the crystals are strongly uniaxial in their mechanical and electronic properties. The calculated moduli of elasticity and resilience along the chain axis are c₁₁ = 320 GPa and E_R = 0.53 GPa, respectively. The electronic band structure and optical conductivity indicate that the crystals are good quasi-one-dimensional conductors. The frequency-dependent complex dielectric tensor ε, calculated in the random-phase approximation, shows a strong Drude peak in ε_∥, i.e., for the electric field polarised parallel to the chain axis, and several peaks related to interband transitions. The electron energy loss spectrum is weakly anisotropic and has a strong peak at the plasma frequency ħω_p ≈20 eV. The stability analysis shows that is metastable against the formation of the layered .