Compressible bag model and the phase structure

The phase structure of hadrons and the quark-gluon plasma is investigated by two types of equation of state of the hadrons, namely the ideal hadron gas model and the compressible bag model. It is pointed out that, while the ideal gas model produces an unrealistic extra hadron phase, the compressible bag model gives the expected and reasonable phase diagram even if the rich hadron spectrum is taken into account. Received: 22 February 2002 / Revised version: 28 June 2002 / Published online: 20 September 2002 RID="a" ID="a" e-mail: kagiyama@sci.kagoshima-u.ac.jp RID="b" ID="b" e-mail: kumamoto@cosmos01.cla.kagoshima-u.ac.jp RID="c" ID="c" e-mail: minaka@edu.kagoshima-u.ac.jp RID="d" ID="d" e-mail: nakamura@sci.kagoshima-u.ac.jp RID="e" ID="e" e-mail: ohkura@cosmos01.cla.kagoshima-u.ac.jp RID="f" ID="f" e-mail: yamaguchi@cosmos01.cla.kagoshima-u.ac.jp     

In-beam spectroscopy of 253, 254No

In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei ^{253, 254}No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyv?skyl?. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of ²⁵³No are discussed. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rdh@ns.ph.liv.ac.uk RID="b" ID="b"Present address: GANIL, F-14021 Caen, France. RID="c" ID="c"Permanent address: IReS Strasbourg, IN2P3-CNRS, F-67037-Strasbourg, France. RID="d" ID="d"Present address: CEA/DIF DCRE/SDE/LDN F-91680 Bruyeres-le-Chatel. RID="e" ID="e"Present address: Daresbury Laboratory, Daresbury WA4 4AD, UK. RID="f" ID="f"Permanent address: IPN Lyon, IN2P3-CNRS, F-69037 Lyon, France.     

Antideuteron production in proton-proton and proton-nucleus collisions

The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most of the existing data without any additional parameter. Received: 18 April 2002 / Accepted: 30 August 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: duperray@isn.in2p3.fr RID="b" ID="b"e-mail: protasov@isn.in2p3.fr RID="c" ID="c"e-mail: avoronin@aha.ru Communicated by A. Molinari     

Interaction of coupled higher order nonlinear Schrödinger equation solitons

The novel inelastic collision properties of two-soliton interaction for an n-component coupled higher order nonlinear Schr?dinger equation are studied. Some interesting features of three soliton interactions, related to the integrability of the n-component coupled higher order nonlinear Schr?dinger equation are also discussed. Received 17 April 2002 Published online 2 October 2002 RID="a" ID="a"e-mail: abhijit@iitg.ernet.in RID="b" ID="b"e-mail: sasanka@iitg.ernet.in RID="c" ID="c"e-mail: sudipta@iitg.ernet.in     

Probing the Majorana mass scale of right-handed neutrinos in mSUGRA

We discuss the perspectives of testing the right-handed Majorana mass scale M_R of the SUSY see-saw model in the mSUGRA framework. Lepton-flavor violating low energy processes are analyzed in recently proposed post-LEP benchmark scenarios, taking into account present uncertainties and future developments in the neutrino sector. Non-observation of in the next-generation PSI experiment will provide upper bounds on M_R of the order of GeV, while on the other hand, a positive signal for at SUPERKEKB or the LHC may determine M_R for a given mSUGRA scenario with an accuracy of a factor of 2. Received: 14 June 2002 / Revised version: 7 January 2003 / Published online: 14 April 2003 RID="a" ID="a" e-mail: deppisch@physik.uni-wuerzburg.de RID="b" ID="b" e-mail: paes@physik.uni-wuerzburg.de RID="c" ID="c" e-mail: asredelb@physik.uni-wuerzburg.de RID="d" ID="d" e-mail: rueckl@physik.uni-wuerzburg.de RID="e" ID="e" e-mail: shimizu@eken.phys.nagoya-u.ac.jp     

Towards high-precision predictions for the MSSM Higgs sector

The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections is discussed. In particular it is shown that the upper bound on m_h within the MSSM is shifted upwards. Consequently, lower limits on obtained by confronting the upper bound as function of with the lower bound on m_h from Higgs searches are significantly weakened. Furthermore, th e region in the M_A--plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up to 3 GeV. Received: 12 December 2002 / Published online: 3 March 2003 RID="a" ID="a" e-mail: giuseppe.degrassi@roma3.infn.it RID="b" ID="b" e-mail: Sven.Heinemeyer@physik.uni-muenchen.de RID="c" ID="c" e-mail: hollik@mppmu.mpg.de RID="d" ID="d" e-mail: slavich@mppmu.mpg.de RID="e" ID="e" e-mail: Georg.Weiglein@durham.ac.uk     

High-spin states in the <Superscript>97</Superscript>Tc nucleus

High-spin states in the ⁹⁷Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction ⁸²Se(¹⁹F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2. The observed level scheme is compared with results of shell model calculations. Received: 22 November 2002 / Accepted: 23 December 2002 / Published online: 18 March 2003 RID="a" ID="a"e-mail: bucurescu@tandem.nipne.ro RID="b" ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy. RID="b" ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy. RID="b" ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy. RID="c" ID="c"Present address: Università di Padova, Padova, Italy. Communicated by C. Signorini     

Laser cooling of molecules via single spontaneous emission

A general scheme for reducing the center-of-mass entropy is proposed. It is based on the repetition of a cycle, composed of three concepts: velocity selection, deceleration and irreversible accumulation. Well-known laser techniques are used to represent these concepts: Raman π-pulse for velocity selection, STIRAP for deceleration, and a single spontaneous emission for irreversible accumulation. No closed pumping cycle nor repeated spontaneous emissions are required, so the scheme is applicable to cool a molecular gas. The quantum dynamics are analytically modelled using the density matrix. It is shown that during the coherent processes the gas is translationally cooled. The internal states serve as an entropy sink, in addition to spontaneous emission. This scheme provides new possibilities to translationally laser-cool molecules for high precision molecular spectroscopy and interferometry. Received 25 June 2002 / Received in final form 28 September 2002 Published online 12 November 2002 RID="a" ID="a"e-mail: ooi@spock.physik.uni-konstanz.de RID="b" ID="b"e-mail: Peter.Marzlin@uni-konstanz.de RID="c" ID="c"e-mail: Juergen.Audretsch@uni-konstanz.de     

Hedgehog production in spatially correlated noise

The production of topological defects during a quench in a φ⁴ model is investigated. The influence of a spatially correlated noise on defect production in two and three dimensions is demonstrated. Received 28 August 2001 / Received in final form 11 February 2002 Published online 2 October 2002 RID="a" ID="a"Paper supported in part by ESF “COSLAB” Programme RID="b" ID="b"e-mail: sfdobrow@kinga.cyf-kr.edu.pl     

Recursive actions for scalar theories

We introduce a class of self-interacting scalar theories in which the various coupling constants obey a recursive relation. These imply a particularly simple form for the generating function of the Feynman amplitudes with vanishing external momenta, as well as for the effective potential. In addition we discuss an interesting duality inherent in these models. Specializing to the case of zero spacetime dimensions we find intriguing nullification properties for the amplitudes. Received: 19 December 2001 / Published online: 5 May 2003 RID="a" ID="a" e-mail: chrisd@sci.kun.nl RID="b" ID="b" e-mail: kleiss@sci.kun.nl RID="c" ID="c" e-mail: petros@sci.kun.nl RID="d" ID="d" e-mail: andrevh@sci.kun.nl RID="e" ID="e" e-mail: papadopo@alice.nuclear.demokritos.gr     

Role of electric field polarisation in rotational transitions

The molecular dynamics of polar diatomic molecule, interacting with linearly and circularly polarised laser field is studied. Non-perturbative quasi-energy technique is used to determine the rotational field surfaces. Degeneracy in different M-levels is found to be removed in the presence of circularly polarised electromagnetic radiation. In this paper, we present the calculations exhibiting the dynamics of rotational excitation of a linear molecule and characteristic features of spectra which become observable in considered fields. Received 22 March 2002 / Received in final form 15 July 2002 Published online 6 November 2002 RID="a" ID="a"e-mail: nsinghal@physics.du.ac.in RID="b" ID="b"e-mail: vnautiyal@himalaya.du.ac.in RID="c" ID="c"e-mail: manmohan@physics.du.ac.in     

Elastica hypoarealis

We examine the equilibria of a rigid loop in the plane, characterized by an energy functional quadratic in the curvature, subject to the constraints of fixed length and fixed enclosed area. Whereas the only non self-intersecting equilibrium corresponding to the fixed length constraint is the circle, the area constraint gives rise to distinct equilibria labeled by an integer. These configurations exhibit self-intersections and bifurcations as the area is reduced. In addition, not only can the Euler-Lagrange equation be integrated to provide a quadrature for the curvature but the embedding itself can be expressed as a local function of the curvature. Perturbations connecting equilibria are shown to satisfy a first order ODE which is readily solved. Analytical expressions for the energy as a function of the area are obtained in the limiting regimes. Received 18 October 2001 / Received in final form 31 May 2002 Published online 2 October 2002 RID="a" ID="a"e-mail: capo@fis.cinvestav.mx RID="b" ID="b"e-mail: chryss@nuclecu.unam.mx RID="c" ID="c"e-mail: jemal@nuclecu.unam.mx     

Production of high quality shocks for equation of state experiments

In this paper we describe the quality requirements that a shock wave must fulfil to make equation of state (EOS) measurements possible: planarity, no-preheating and stationarity of the shock. Experimental measurements have been performed at the Max Planck Institut für Quantenoptik (Garching). We also present simple analytical models that allow to verify shock stationarity and absence of preheating. Received 17 June 2002 Published online 21 January 2003 RID="a" ID="a"e-mail: batani@mib.infn.it RID="b" ID="b"Present address: Pro-beam, Behrinsta?e 6, 85152 Planegg b. München, Germany. RID="c" ID="c"UMR 7605     

How well can we reconstruct the $t\bar{t}$ system near its threshold at future ee linear colliders?

We developed a new method for the full kinematical reconstruction of the system near its threshold at future linear e ⁺ e ^- colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical variables that specify the final states resulting from decays. The improvement is demonstrated by applying this method to a Monte Carlo sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector system, etc. In most cases the fit takes a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of the parton-level momenta. The standard deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological analyses. A possible application of the kinematical fitting method and its expected impact are also discussed. Received: 4 March 2003 / Published online: 23 May 2003 RID="a" ID="a" e-mail: ikematsu@post.kek.jp RID="b" ID="b" e-mail: fujiik@jlcuxf.kek.jp RID="c" ID="c" e-mail: hioki@ias.tokushima-u.ac.jp RID="d" ID="d" e-mail: sumino@tuhep.phys.tohoku.ac.jp RID="e" ID="e" e-mail: tohrut@hiroshima-u.ac.jp     

Baryon number transfer in hadronic interactions

The process of baryon number transfer due to string junction propagation in rapidity space is analyzed. It has a significant effect on the net baryon production in pp collisions at mid-rapidities and an even larger effect in the forward hemisphere in the cases of and interactions. The results of numerical calculations in the framework of the quark-gluon string model are in reasonable agreement with the data. Received: 14 December 2001 / Revised version: 24 April 2002 Published online: 16 October 2002 RID="a" ID="a" Permanent address: Yerewan Physics Institute, Armenia and JINR, Dubna, Russia e-mail: argev@jerewan1.yerphi.am RID="b" ID="b" e-mail: Alphonse.Capella@th.u-psud.fr RID="c" RID="d"     

A universal Regge pole model for all vector meson exclusive photoproduction by real and virtual photons

A model based on a dipole pomeron framework for exclusive vector meson photoproduction by real and virtual photons shows very good agreement with the experimental data. This model does not violate unitarity constraints and describes in a universal manner all the available data for , , , and vector meson photoproduction in the region of energies and photon virtualities . Received: 18 December 2001 / Published online: 25 October 2002 RID="a" ID="a" e-mail: martynov@bitp.kiev.ua RID="b" ID="b" e-mail: predazzi@to.infn.it RID="c" ID="c" e-mail: prokudin@to.infn.it     

Structure and properties of confined sodium nitrite

We study the lateral and transverse diffusion of amphiphiles in two-component bilayer membranes, using a coarse-grained model for amphiphilic molecules and combined Monte Carlo-Molecular Dynamics simulations. Membrane structural properties, such as the mean thickness, are also measured. The dependence of such properties on membrane composition, inter-molecular interactions, and amphiphile stiffness is determined. In particular, we show that addition of shorter amphiphiles drives the model membrane towards a more fluid state, with increased amphiphile lateral diffusion rates. These results can be understood in the framework of a simple free-volume model. Furthermore, we observe an increase in the trans-membrane diffusion when the interaction energy of amphiphiles with their neighboring molecules is decreased. Received: 6 December 2002 / Accepted: 17 April 2003 / Published online: 27 May 2003 RID="a" ID="a"e-mail: imparato@mpikg-golm.mpg.de RID="b" ID="b"e-mail: shillcock@mpikg-golm.mpg.de RID="c" ID="c"e-mail: lipowsky@mpikg-golm.mpg.de     

World-line techniques for resumming gluon radiative corrections at the cross-section level

We employ the Polyakov world-line path-integral version of QCD to identify and resum at leading perturbative order enhanced radiative gluon contributions to the Drell-Yan type ( pair annihilation) cross-sections. We emphasize that this is the first time that world-line techniques are applied to cross-section calculations. Received: 10 June 2002 / Published online: 31 October 2002 RID="a" ID="a" e-mail: akaranik@cc.uoa.gr RID="b" ID="b" e-mail: cktorid@cc.uoa.gr RID="c" ID="c" e-mail: stefanis@tp2.ruhr-uni-bochum.de