Sessions - DPG-Tagungen

More documents

Recommendations

Info

Nuclear Physics Wednesday of the accelerator average to zero very fast. A planar figure of 8 accelerator without any horizontal magnetic field components would restore any spin orientation at a given position in every turn. Small horizontal disturbances, especially from fringe fields will lead to comparatively slow spin movement which will make in average polarisation zero. If this movement is slow enough and coherent one might use this in experiments. Combination of the crossover accelerator structure with Wienfilters or Solenoids open some new possibilities for spin stabilization. HK 25.6 Wed 12:15 C CONCEPTUAL DESIGN OF A HIGH CURRENT DEUTERON RFQ — •Chuan Zhang 1 , Alwin Schempp 1 , Zhi-Yu Guo 2 , Jia-Er Chen 2 , and Jia-Xun Fang 2 — 1 Iap Frankfurt — 2 IHIP, Peking University A 50mA deuteron RFQ is proposed for the thermal neutron generator project at Peking University, China. Design studies have been performed with the ParmteqM and Microwave Studio codes to optimize the structure design, concerning minimum beam losses, the limited RF power and the demands of safety maintenance. Results of a conceptual design with a compact structure and high transmission efficiency is presented. HK 26 Theory IV HK 25.7 Wed 12:30 C Development of finger drift tubes — •Kai-Uwe Kuehnel 1 , Carsten Peter Welsch 2 , and Alwin Schempp 1 — 1 IAP Frankfurt — 2 MPI-K Heidelberg Since RFQs decrease in their acceleration efficiency at higher energies and drift tube structures have a defocussing effect on the beam, a new kind of drift tube linac is being studied in Frankfurt. By mounting small fingers with quadrupole symmetry on the drift tubes, a focusing field component is added to the accelerating field. Driven by the same power supply as the drift tubes, the fingers do not need an additional power source or feedthrough. The beam dynamics of such a cavity has been examined with PARMTEQ. Simulations of the rf properties have been done using microwave studio. A prototype of a spiral loaded cavity with finger drift tubes has been built and examined. Results of the calculations as well as low level and bead pertubation measurements are presented in this contribution. Time: Wednesday 10:45–12:45 Room: D Group Report HK 26.1 Wed 10:45 D Nucleon mass, sigma term and lattice QCD — •Massimiliano Procura 1,2 , Thomas Hemmert 1 , and Wolfram Weise 1,2 — 1 Physik Department, Theoretische Physik T39, TU München, Germany — 2 ECT ∗ , Trento, Italy. We analyse the quark mass dependence of the nucleon mass in relativistic SU(2) baryon chiral perturbation theory as described in [1]. In such a framework we perform an interpolation of this nucleon property between a selected set of fully dynamical two-flavor lattice QCD data [2] and its physical value. We obtain a good interpolation function already at the one-loop level. We show that the next-to-leading one-loop corrections are small. Using results from such analysis we study also the quark mass dependence of the pion-nucleon sigma term. Work supported in part by BMBF and DFG. [1] T. Becher and H. Leutwyler, Eur. Phys. J. C9, 643 (1999). [2] M. Procura, T. Hemmert and W. Weise, [hep-lat/0309020], submitted to Phys. Rev. D. HK 26.2 Wed 11:15 D The Nucleon in a Box — •T.R. Hemmert for the QCDSF and UKQCD collaboration — Physik Department T39, TU München The quark mass dependence of the nucleon in relativistic baryon chiral perturbation theory (BChPT) has been discussed to next-to-leading one loop order in [1]. It was found that the resulting chiral extrapolation formula agrees well with lattice QCD simulation data for effective lattice pion masses between 500-750 MeV, provided that one selects only those simulation points obtained at lattice sizes larger than 1.8 fm. When the size of the simulation volume is further reduced, the quark mass dependence of the mass of the nucleon is different from the one given in [1], due to greater sensitivity to the exact boundary conditions of the finite box size. These finite size effects on the nucleon mass have been calculated [2], utilizing the same relativistic BChPT framework. At next-to-leading one loop order one finds good agreement between the volume dependence predicted by ChPT and the finite size effects observed in lattice QCD simulations. We also discuss how finite size effects in lattice QCD simulations of baryon properties can be understood within the framework of ChPT [3]. [1] M. Procura, T.R. Hemmert and W. Weise, [hep-lat/0309020]. [2] QCDSF and UKQCD collaboration, [hep-lat/0309133]. [3] QCDSF and UKQCD collaboration, forthcoming. This work has been supported in part by BMBF and DFG. HK 26.3 Wed 11:30 D Chiral Extrapolations and Non-Analytic Terms — •Dominik Nickel, Michael Buballa, and Jochen Wambach — IKP, TU Darmstadt, Germany Since lattice QCD is so far limited to unrealistically large quark masses (corresponding to pion masses of 400 MeV or more), the resulting observables must be extrapolated to the physical point. Usually this is done by simple polynomial fits to the data. It has also been suggested to employ chiral models for the extrapolations in order to ensure the correct non-analytic behavior in the chiral limit. In this talk, we investigate the relevance of the leading non-analytic (LNA) terms and present results obtained with the 1/Nc-corrected NJL model. It will be shown that the LNA terms, which are also formally reproduced correctly by the NJL model, give a very poor description of the mπ dependence of the hadron masses, mainly because of the implicit definition of the masses as the poles of the dressed propagators. HK 26.4 Wed 11:45 D Excited nucleons on the lattice with chirally improved fermions — •Dirk Brömmel 1 , Peter Crompton 1 , Christof Gattringer 1 , Leonid Ya. Glozman 2 , C.B. Lang 2 , Stefan Schaefer 3 , and Andreas Schäfer 1 for the BGR [Bern - Graz - Regensburg] collaboration — 1 Universität Regensburg — 2 Universität Graz — 3 University of Colorado at Boulder We study positive and negative parity nucleons on the lattice using the chirally improved lattice Dirac operator. Our analysis is based on a set of three operators χi with the nucleon quantum numbers. We use a variational method to separate ground state and excited states and determine the mixing coefficients for the optimal nucleon operators in terms of the χi. We clearly identify the negative parity resonances N(1535) and N(1650) and their masses agree well with experimental data. The mass of the observed excited positive parity state is too high to be interpreted as the Roper state. Our results for the mixing coefficients indicate that chiral symmetry is important for N(1535) and N(1650) states. HK 26.5 Wed 12:00 D I = 2 pion scattering length with chirally improved fermions — •Dieter Hierl, Christof Gattringer, Rainer Pullirsch, and Andreas Schäfer — Institut für theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany We report on a lattice calculation of the pion scattering length in the I = 2 channel using the chirally improved lattice Dirac operator. The scattering length is extracted by using the standard finite volume technique of Lüscher. We find that the most difficult part is to minimize the errors for the 4-pion-correlators. We work with pion masses down to 310 MeV in the quenched approximation. The scattering lengths we obtained are extrapolated to the chiral limit. We find a good agreement with experimental data.
Nuclear Physics Wednesday HK 26.6 Wed 12:15 D Automated Lattice Perturbation Theory and Decays of Heavy Quarkonia — •G.M. von Hippel 1 , R.R. Horgan 1 , and A.G. Hart 2 — 1 DAMTP, University of Cambridge, England — 2 University of Edinburgh, Scotland We present a method for the automated generation of vertices in perturbative Lattice QCD using a Python script, which due to its modular structure can easily be adapted for pure gauge theory, staggered fermions, or other fermionic actions, including NRQCD. As an example, we show how to compute the matching coefficients for S-wave decays of heavy quarkonia between Lattice NRQCD and continuum QCD to O(αsv 2 ) using our methods. HK 26.7 Wed 12:30 D The Quark-Mass Dependence of TC in QCD: Working up from m = 0 or down from m = ∞ ? — •Dirk Röder, Adrian Dumitru, and Jörg Ruppert — JWG-Universität, Robert-Mayer-Str.10, D-60054 Frankfurt am Main We analyze the dependence of the QCD transition temperature on the quark (or pion) mass. We find that a linear sigma model, which links the transition to chiral symmetry restoration, predicts a much stronger de- > pendence of Tc on mπ than seen in present lattice data for mπ ∼ 0.4 GeV. On the other hand, working down from mπ = ∞, an effective Lagrangian for the Polyakov loop requires only small explicit symmetry breaking, b1 ∼ exp(−mπ), to describe Tc(mπ) in the above mass range. Physically, this is a consequence of the flat potential (large correlation length) for the Polyakov loop in the three-color pure gauge theory at Tc. We quantitatively estimate the end point of the line of first order deconfining phase transitions: mπ ≃ 4 √ σ ≃ 1.7 GeV for Nf = 3. HK 27 Electromagnetic and Hadronic Probes IV Time: Wednesday 10:45–12:45 Room: E Group Report HK 27.1 Wed 10:45 E GDH sum rule completed up to 3 GeV — •Jochen Krimmer for the GDH collaboration — Physikalisches Institut der Universität Tübingen, Germany The GDH sum rule connects helicity dependent total photoabsorption cross sections with static properties of the nucleon like the mass and the anomalous magnetic moment. Experiments for its direct experimental check have been performed at the tagged photon facilities of the electron accelerators MAMI and ELSA. Circularly polarized photons have been used together with a longitudinally polarized nucleon target and 4π detector systems. As the experiments cover an energy range from 200 MeV to 3 GeV, double polarized photoabsorption cross sections are available for the first time from the resonance region to the onset of Regge behaviour. Furthermore, exploratory data have been taken on the neutron with a polarized 6 LiD target. This work is supported by DFG under contract GRK683 & GR1084/5-1. HK 27.2 Wed 11:15 E Status of the GDH-Experiment on the deuteron at MAMI — •Andreas Thomas for the A2-collaboration collaboration and the nGDH-collaboration collaboration — Institut f”ur Kernphysik Universit”at Mainz A pilot experiment to determine the helicity dependend total and partial photoabsorption cross sections had been carried out in 1998 at MAMI. The full data taking period was sucessfully finished in the first half of 2003. We have used the circularly polarized energy marked photons of the Mainz A2 tagging facility. For this experiments the Bonn- Bochum frozen spin was integrated into the 4π DAPHNE detector. In this talk the experimental setup, preliminary results of the pilot experiment and the status of the data analysis will be presented. HK 27.3 Wed 11:30 E Dynamics of the ω Meson Production in the Reaction pp → ppω — •M. Schulte-Wissermann, K.-T. Brinkmann, S. Dschemuchadse, H. Freiesleben, R. Jäkel, L. Karsch, and G.Y. Sun for the COSY-TOF collaboration — TU-Dresden The ω meson production in nucleon-nucleon interactions has recently attracted considerable interest on the part of both experimental and theoretical physics. The elementary reaction dynamics is needed as an inevitable prerequisite in many fields of physics; e.g. the short range part of the nucleonic force (meson exchange models), the description of extremely dense matter (RHIC, cosmology), the strangeness content of nucleons (nuclear physics). However, the experimental database is far from complete, especially for differential observables. Furthermore, no experimental indication for Nω resonances has been found so far. New experimental data with high accuracy are desired. Due to its good solid angle coverage, the TOF-detector located at COSY is well suited to examine ω production in the reaction pp → ppω. At excess energies of 93 and 173MeV the ω signal is clearly identified above background. Total cross sections and angular distributions for both energies will be presented, where the latter are isotropic at 93MeV while strongly anisotropic at 173MeV . Although still compatible with phasespace within uncertainty limits, the invariant mass distributions of the pω-system may indicate a pω-resonance near the lower mass boundary. (Supported by BMBF and FZ-Jülich) HK 27.4 Wed 11:45 E Omega photoproduction off solid targets — •David Trnka for the CBELSA/TAPS collaboration — II. Physikalisches Institut, Heinrich- Buff-Ring 16, 35392 Giessen Omega photoproduction off solid targets is a powerfull tool to investigate possible in-medium modifications of hadronic properties. A variety of theoretical models predict a shift of the omega meson mass in the order of −140MeV < m ∗ −mV < −15MeV and a broadening of the width within a range of 20 to 50 MeV at normal nuclear densities (i.e. :[1]). From March to May 2003 data off C, Ca, Nb and Pb has been obtained at the ELSA accelerator facility in Bonn using the combined detector system of Crystal Barrel and TAPS, providing an almost 4π coverage for photon (and also charged particle) detection. The incident electron beam energy was chosen to be 2.8 GeV. The photon beam is produced via the Bremsstrahlung process off a thin radiator, covering a tagged range of 31 to 94 % of the incident beam energy. The Reaction γ + A → ω + X is identified via the decay mode ω → π 0 +γ → γγγ by detecting the three photons. Simulations ([2]) prove the feasibility of measuring in-medium modifications and show that distortions due to FSI of the pions can be eliminated. First indications of an ω mass shift have been observed and the dependence on the ω-momentum has been studied. These prelimary results will be compared to recently published calculations, which take the experimental resolution into account ([3]). [1] T. Renk et al. , Phys. Rev. C 66, (2002) 014902 [2] J. G. Messchendorp et al. , Eur. Phys. J. A. 11, 95-103 (2001) [3] P. Mühlich et al., arXiv:nucl-th/0310067 HK 27.5 Wed 12:00 E Exclusive Measurements of the �pp → ppπ + π − Reaction at COSY- TOF ∗ — •A. Erhardt, J. Kress, H. Clement, E. Doroshkevich, and G.J. Wagner for the COSY-TOF collaboration — Physikalisches Institut, Universität Tübingen By use of the COSY vector polarized proton beam the �pp → ppπ + π − reaction has been measured at COSY-TOF at two different energies, Tp = 750 and 800 MeV, i.e. close to threshold. Time-of-flight information and track reconstruction has been obtained by use of the informations supplied by start, fiber, quirl and ring hodoscopes, whereas particle identification and energy information has been provided by the central calorimeter. In addition, delayed pulse technique has been utilized for a positive identification of π + particles. The dominant part of the extracted data samples consist of completely measured 4 prong events, i.e. exclusively measured events with 4 overconstraints each. This way very clean data have been obtained. The resulting differential spectra for invariant masses, angular distributions and analyzing powers will be presented and discussed with respect to model calculations for σ meson production
Page 1 and 2: Nuclear Physics Sectional Programme
Page 3 and 4: Nuclear Physics Monday HK 2.8 Mon 1
Page 7 and 8: Nuclear Physics Monday and Gso(kf)
Page 11 and 12: Nuclear Physics Monday correlations
Page 13 and 14: Nuclear Physics Tuesday doublet ban
Page 15 and 16: Nuclear Physics Tuesday MeV, meant
Page 17 and 18: Nuclear Physics Tuesday can be expe
Page 19 and 20: Nuclear Physics Tuesday HK 11.19 Tu
Page 21 and 22: Nuclear Physics Tuesday of 20 - 120
Page 23 and 24: Nuclear Physics Tuesday HK 12.9 Tue
Page 25 and 26: Nuclear Physics Tuesday Electrostat
Page 27 and 28: Nuclear Physics Tuesday and we quan
Page 29 and 30: Nuclear Physics Tuesday Experiment)
Page 31 and 32: Nuclear Physics Tuesday data sample
Page 33 and 34: Nuclear Physics Tuesday HK 16 Nucle
Page 35 and 36: Nuclear Physics Tuesday first deter
Page 37 and 38: Nuclear Physics Tuesday HK 18.7 Tue
Page 39 and 40: Nuclear Physics Tuesday croscopic c
Page 41 and 42: Nuclear Physics Tuesday HK 21 Heavy
Page 43 and 44: Nuclear Physics Wednesday Plenary T
Page 45: Nuclear Physics Wednesday Due to th
Page 49 and 50: Nuclear Physics Wednesday One way t
Page 51 and 52: Nuclear Physics Wednesday sion we h
Page 53 and 54: Nuclear Physics Wednesday with an a
Page 55 and 56: Nuclear Physics Wednesday excitatio
Page 57 and 58: Nuclear Physics Wednesday in the co
Page 59 and 60: Nuclear Physics Thursday HK 37.6 Th
Page 63 and 64: Nuclear Physics Thursday HK 41 Heav
Page 65 and 66: Nuclear Physics Thursday populated
Page 67 and 68: Nuclear Physics Thursday indication
Page 69 and 70: Nuclear Physics Thursday detectors
Page 73 and 74: Nuclear Physics Friday HK 49 Plenar
Page 75 and 76: verzagt 1 , R. VanderVyver 19 , Th.
Page 77 and 78: H. Soltner 1 , H. Glückler 1 , H.
Page 79 and 80: N. Kurz 1 , B. Lommel 1 , W. Mittig
Page 81 and 82: Fassò, A. ...................HK 12
Page 83 and 84: Novikov, Yu. N. .. HK 2.2, HK 2.4,

Sessions - DPG-Tagungen

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?