Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session KD: Hadronic Physics II |
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Chair: T. Nakano, RCNP Osaka Room: Kohala 4 |
Saturday, October 17, 2009 9:00AM - 9:15AM |
KD.00001: Measurement of Induced Polarization of $\Lambda$(1116) in Kaon Electroproduction With CLAS M.Y. Gabrielyan, B.A. Raue, S. Dhamija, D.S. Carman The CLAS Collaboration is using the $p(e,e'K^+p)\pi^-$ reaction to perform a measurement of the induced polarization of the electroproduced $\Lambda$(1116). The parity-violating weak decay of the $\Lambda$ into $p\pi^{-}$ (64\%) allows extraction of the recoil polarization of the $\Lambda$. This study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton. CLAS allows for a large kinematic acceptance in $Q^2$ ($0.73\leq Q^2\leq 3.5$ GeV$^2$), $W$ ($1.6\leq W \leq 3.0$ GeV), as well as the kaon scattering angle. In this experiment a 5.499 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for models of the electromagnetic production of $K$-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, and GRAAL, these data will ultimately be useful in coupled-channel analyses and will potentially help identify previously unobserved or poorly determined $s$-channel resonance terms. Preliminary results will be presented. [Preview Abstract] |
Saturday, October 17, 2009 9:15AM - 9:30AM |
KD.00002: ABSTRACT WITHDRAWN |
Saturday, October 17, 2009 9:30AM - 9:45AM |
KD.00003: Determination of the linear polarization of the Hall B tagged photon beam at JLab Arthur Sabintsev The CLAS g9a experiment is part of the N* spectroscopy program at Jefferson Laboratory and has accumulated photoproduction data using a linearly polarized, tagged photon beam incident on a longitudinally polarized, frozen spin butanol target (FROST). Linearly polarized photons were produced via coherent bremsstrahlung from an electron beam incident on an oriented diamond crystal.\footnote{U. Timm, ``Coherent Bremsstrahlung of Electrons in Crystals.'' (1969), \textit{Fortschritte der Physik} \textbf{17}, 765-808.} The degree of polarization depends on the position of the coherent bremsstrahlung peak and at some settings, may exceed 90\%. The analysis of the spectrum shape was used to determine photon polarization. This report delineates the procedure and presents the results of these determinations. [Preview Abstract] |
Saturday, October 17, 2009 9:45AM - 10:00AM |
KD.00004: Photoproduction of $\Lambda $(1405) and $\Sigma ^{0}$(1385) on the proton at E$\gamma $=1.5 - 3.0 GeV at SPring-8/LEPS Yohei Nakatsugawa The $\Lambda $(1405) is assigned as a p-wave q3 baryon in a quark model. However, it is also suggested that $\Lambda $(1405) has a non-q3 structure such as a meson-baryon molecular state. On the other hand, $\Sigma ^{0}$(1385) is firmly established as a q3 state baryon. The difference of the internal structure of $\Lambda $(1405) and $\Sigma ^{0}$(1385) may appear in the photoproduction cross sections and/or photon beam asymmetries of these two hyperons. Recently, differential cross sections for $\gamma $p $\to $ K$^{+}\Lambda $(1405) and $\gamma $p $\to $ K$^{+}\Sigma ^{0}$(1385) reactions were measured by LEPS collaboration. However, the statistics were limited because the contribution of free protons in the CH$_{2}$ target was extracted by subtracting carbon contributions which were dominant. A new experiment was carried out with liquid hydrogen target and linearly polarized photon beam. In order to detect decay products of hadrons, a time projection chamber surrounding the liquid target was used together with the LEPS spectrometer. The integrated luminosity is about 3 times larger than that of the previous experiment in the photon energy range E$\gamma $=1.5 - 2.4 GeV. In addition, we can access higher photon energy region because the maximum E$\gamma $ of 2.97 GeV was achieved. The more detailed information of differential cross sections of $\gamma $p $\to $ K$^{+}\Lambda $(1405) and $\gamma $p $\to $ K$^{+}\Sigma ^{0}$(1385) and line shapes of $\Lambda $(1405) will be obtained from new data. The photon beam asymmetry will be also investigated. [Preview Abstract] |
Saturday, October 17, 2009 10:00AM - 10:15AM |
KD.00005: Production of hyperon resonances induced by kaon on deuteron target Junko Yamagata-Sekihara, Takayasu Sekihara, Daisuke Jido The kaon induced production of hyperon resonances is investigated in $K^-d\to Y^{*} N$ reactions based on coupled channels chiral dynamics. The notable feature of this reaction is that the hyperon resonances located below the ${\bar K}N$ threshold, such as the $\Lambda(1405)$ and $\Sigma(1385)$ resonance, can be produced by the ${\bar K}N$ channel. Also for the hyperon resonances appearing above the $\bar KN$ threshold, owing to this unique kinematics, this reaction gives us complementary information of the production properties to those in the direct reaction. It has been already known that this model successfully describes the $\Lambda(1405)$ production in this reaction. For the systematical study, we apply this model to other hyperon resonances, for example $\Sigma(1385)$, $\Lambda(1520)$ and $\Lambda(1670)$. We show the cross section of this reaction and discuss the properties of the hyperon resonances. [Preview Abstract] |
Saturday, October 17, 2009 10:15AM - 10:30AM |
KD.00006: Unquenched Lattice QCD study of $\Lambda$(1405) Toru Takahashi, M. Oka $\Lambda$(1405) is regarded as one of the most interesting hadrons and attracting much interest from several view points. Especially, the structure of $\Lambda$(1405) remains mysterious. Whereas $\Lambda$(1405) is interpreted as a flavor-singlet three-quark state in quark models, $\Lambda$(1405) could be interpreted as a Kaon-nucleon molecule. $\Lambda$(1405) is then considered to be a bound-state of $\bar K$ and $N$ with binding energy of 30 MeV, and this large binding energy implies strong attraction between $\bar K$ and $N$. Such strong attractive interactions predict a new type of hadronic matter. The property of $\Lambda$(1405) can be therefore an important clue to new paradigm in hadron physics. Lattice QCD calculations are powerful, and expected to cast light on the nature of $\Lambda$(1405). However, few detailed lattice QCD study on $\Lambda$(1405) have been done so far. We study properties of $\Lambda$(1405) with lattice QCD. We make use of the full-QCD gauge configurations generated by CP-PACS/PACS-CS collaboration. We construct correlation matrices from several independent ``octet'' and ``singlet'' operators, and diagonalize them so that we can investigate mass spectra in (J, I, S)=(1/2, 0, -1) channel as well as possible mixing between octet and singlet states, which has not been discussed yet in the context of lattice QCD studies. As a result, we found that the lowest (2nd-lowest) state in this channel is dominated by a flavor-singlet (flavor-octet) state. We also extract the $\bar KN$ and $\pi\Sigma$ components in each observed state. [Preview Abstract] |
Saturday, October 17, 2009 10:30AM - 10:45AM |
KD.00007: Dynamical coupled-channels study of photo- and electro-production reactions H. Kamano, B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, T. Sato, N. Suzuki A comprehensive study of the meson production reactions with initial $\pi N$, $\gamma N$, and $N(e,e')$ based on a dynamical coupled-channels approach is being made to explore the structure of the $N^\ast$ states in the Excited Baryon Analysis Center (EBAC) at Jefferson Lab. In this talk we present a current status of our study of the photo- and electro-production reactions, particularly focusing on the single and double pion production reactions. We will also discuss what impact the so-called ``complete-measurement'' of single pseudoscalar meson photoproduction reactions has on the construction of reaction models, which is a key to the precise determination of the N* properties. [Preview Abstract] |
Saturday, October 17, 2009 10:45AM - 11:00AM |
KD.00008: Electromagnetic form factor of nucleon resonances from meson production N. Suzuki, B. Julia-Diaz, H. Kamano, T.-S. H. Lee, A. Matsuyama, T. Sato The nucleon resonances appear as poles of the scattering amplitudes on the complex energy plane. The masses of $N^*$ and the electromagnetic $NN^*$ transition form factors are obtained from the pole positions and the residues of the scattering amplitudes. We have developed a method of analytic continuation to extract resonance parameters from the amplitudes of the dynamical reaction model, which includes unstable particle channels such as $\pi\Delta, \sigma N$ and $\rho N$. We apply the method for the $\pi N$ and $\gamma^* N$ amplitudes from our coupled channel model of meson production reactions. The extracted $NN^*$ form factors for a few $N^*$ resonances will be presented. [Preview Abstract] |
Saturday, October 17, 2009 11:00AM - 11:15AM |
KD.00009: Nucleon resonances in $K$ and $T$ matrix calculations and fits Mark Paris, R. Arndt, W. Briscoe, I. Strakovsky, R. Workman The characterization of resonances of the nucleon is considered in extractions from multichannel hadronic $K$ and $T$ matrices. We obtain the poles of the $K$ matrix and their relation to the poles of the $T$ matrix as determined from the SAID multichannel, unitary fit to observed cross sections and asymmetries. We study the dependence of $K$ and $T$ matrix structures on the fit parameterization. We also make comparisons to a dynamical model calculation of the inelastic hadronic amplitudes. [Preview Abstract] |
Saturday, October 17, 2009 11:15AM - 11:30AM |
KD.00010: Thirty Unsolved Problems in the Physics of Elementary Particles V. Christianto, Florentin Smarandache Unlike what some physicists and graduate students used to think, that physics science has come to the point that the only improvement needed is merely like adding more numbers in decimal place for the masses of elementary particles or gravitational constant, there is a number of unsolved problems in this field that may require that the whole theory shall be reassessed. In the present article we discuss thirty of those unsolved problems and their likely implications. In the first section we will discuss some well-known problems in cosmology and particle physics, and then other unsolved problems will be discussed in next section. [Preview Abstract] |
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