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 LD: Hadronic Physics III |
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Chair: Simon Capstick, Florida State University Room: Kohala 4 |
Saturday, October 17, 2009 2:00PM - 2:15PM |
LD.00001: Studies on exotic hadrons at Belle Toru Iijima In this talk, we will present updated results on exotic hadrons from the Belle experiment at KEK. First, we will present results from reanalysis of the Z(4430)+ resonance using the Dalitz plot technique. We have observed the signal peak with more than 6 sigma significance, consistent with our previous measurement. We will also present some more new results obtained by Summer 2009. Then, we will present on the plan for the upgrade of the KEKB accelerator and the Belle detector to the Super-KEKB and Belle II, and discuss future prospects of research in this area [Preview Abstract] |
Saturday, October 17, 2009 2:15PM - 2:30PM |
LD.00002: X(3872) as a coupled two-meson molecular state with a tetraquark configuration Sachiko Takeuchi, Makoto Takizawa, Kiyotaka Shimizu X(3872) may be a superposition of the two-meson molecular states and the compact tetraquark state because the X(3872) mass is very close to or almost on the threshold and because the quark interaction can be attractive for the tetraquark state. In order to understand its structure, we employ a quark model where the orbital correlations of the four quarks are fully taken into account. The parameters in the model are taken so that the relevant $q\overline{q}$ meson mass spectrum as well as the $S$-wave baryon mass spectrum are reproduced. We also consider the $c\overline{c}$ core for the isospin $I$=0 system. The results show that there can be such a bound state, namely a two-meson molecule with a compact tetraquark configuration in the short range region, for each of the $I$=0 and 1 systems. Their masses can be very close to each other. When the isospin symmetry breaking terms, namely the electromagnetic interaction between quarks as well as the $ud$-quark mass difference, are introduced to the system, the effect of the mixing between the $I$=0 and 1 states can be large. This may be the mechanism of the observed large isospin symmetry breaking of X(3872). [Preview Abstract] |
Saturday, October 17, 2009 2:30PM - 2:45PM |
LD.00003: Exotic Charm Mesons X(3872) and Z(4430) with Multi-Hadronic Components Makoto Takizawa, Sachiko Takeuchi In order to understand the structure of the X(3872), we have studied the effects of the $c \bar c$ core state coupling to the multi-hadronic states such as $D^0$$\overline{D^{0\ast}}$, $\rho$ $J/\psi$ etc. We have calculated the transition strength $S(E)$ using the Green's function approach with the simple solvable interactions. We have also studied the $S(E)$ in the case of no $c \bar c$ core state, namely, the $D^0$ $\overline{D^{0\ast}}$ molecule. Since the calculated shapes of the transition strengths are different from each other, we shall be able to determine the degree of the mixing of the $c \bar c$ state in the X(3872) from the shape of the energy spectrum. We shall also study the structure of the Z(4430) in the similar approach, namaly, the tetraquark core state coupling to the $D^{\ast}(2010)$$D_1(2420)$, $\pi$$\psi'$, etc. in the Green's function approach. [Preview Abstract] |
Saturday, October 17, 2009 2:45PM - 3:00PM |
LD.00004: Exotic nuclei with open heavy flavor mesons Shigehiro Yasui, Kazutaka Sudoh We discuss stable exotic nuclei bound with $\bar{D}$ and $B$ mesons with respecting heavy quark symmetry. We indicate that an approximate degeneracy of $\bar{D}$($B$) and $\bar{D}^{*}$($B^{*}$) mesons plays an important role, and discuss the stability of $\bar{D}N$ and $BN$ bound states. We find the binding energies 1.4 MeV and 9.4 MeV for each state in the $J^{P}=1/2^{-}$ with $I=0$ channel, and no bound states with the other channels. These states are stable in the strong decay, and can be observed in the weak decay processes $\bar{D} N \rightarrow K^{+}\pi^{-} \pi^{-} + p$, and $B N \rightarrow D^{-}\pi^{+} + p$. We discuss also possible existence of exotic nuclei $\bar{D}NN$ and $BNN$. The existence of $\bar{D}N$ and $BN$ bound states would provide an opportunity to probe new exotic states near the thresholds, and, as well as strangeness nuclei, open a new way to investigate for exotic nuclei with variety of multi-flavor explored at future hadron facilities such as J- PARC (Japan Proton Accelerator Research Complex) and GSI (Gesellschaft f\"ur Schwerionenforschung). [Preview Abstract] |
Saturday, October 17, 2009 3:00PM - 3:15PM |
LD.00005: Charmed and Bottom baryon spectrum from Lattice QCD Kosnstantinos Orginos We compute the masses of the singly and doubly charmed baryons in full QCD using the relativistic Fermilab action for the charm quark. For the light quarks we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We use the low-lying charmed meson spectrum to tune our heavy-quark action and as a guide to understanding the discretization errors associated with the heavy quark. Our results are in good agreement with experiment within our systematics. In addition we predict the mass of the (isospin averaged) spin-1/2 $\Omega_{cc}$ to be 3680(31)(36)(11)~MeV. In addition We calculate bottom-hadron mass splittings with respect to $B_d$ and $\Lambda_b$ in the static limit for the heavy quark. Our results are in agreement with experimental observations and other lattice calculations within our statistical and systematic errors. In particular, we find the mass of the $\Omega_b$ to be consistent with the recent CDF measurement. We also predict the mass for the as yet unobserved $\Xi^\prime_b$ to be 5955(27)~MeV. [Preview Abstract] |
Saturday, October 17, 2009 3:15PM - 3:30PM |
LD.00006: ABSTRACT WITHDRAWN |
Saturday, October 17, 2009 3:30PM - 3:45PM |
LD.00007: S=+1 pentaquarks in QCD sum rules Philipp Gubler, Daisuke Jido, Toru Kojo, Tetsuo Nishikawa, Makoto Oka The QCD sum rule technique is employed to investigate pentaquark states with strangeness $S = +1$ and $IJ^{\pi} = 0\frac{1}{2}^{\pm},1\frac{1}{2}^{\pm},0\frac{3}{2}^ {\pm},1\frac{3}{2}^{\pm}$. Throughout the calculation, we emphasize the importance of the establishment of a valid Borel window, which corresponds to a region of the Borel mass, where the operator product expansion (OPE) converges and the presumed ground state pole dominates the sum rules. Such a Borel window is achieved by constructing the sum rules from the differenece of two carefully chosen independent correlators and by calculating the OPE up to dimension 14. As a result, we conclude that the state with qauntum numbers $0\frac{3}{2}^{+}$ state appears to be the most probable candidate for the experimantally observed $\Theta^ {+}(1540)$, while we also obtain states with $0\frac{1}{2}^{-},1\frac{1}{2}^{-},1\frac{3}{2}^{+}$ at somewhat higher mass regions. We furthermore discuss the contribution of the $KN$ scattering states to the sum rules, and the possible influence of these states on our results. [Preview Abstract] |
Saturday, October 17, 2009 3:45PM - 4:00PM |
LD.00008: Spin transfer in $\bar{p}p\rightarrow\bar{\Lambda}\Lambda$ Mary Alberg A complete determination of spin observables for $\bar{p}p\rightarrow\bar{\Lambda}\Lambda$, at an antiproton lab momentum of 1.637 GeV/c, has been made by the PS185 Collaboration. The results of this experiment disagree strongly with the predictions of calculations which used either meson-exchange or quark models for the reaction mechanism. The experiment will be repeated at FAIR by the PANDA Collaboration, and extended to higher energies. A model-independent description of the spin structure of this reaction is provided by the transition matrix $M$, which can be written in the center of mass frame as a function of 6 complex parameters. These parameters are also determined by any model calculation for $\bar{p}p\rightarrow\bar{\Lambda}\Lambda$, so they are related to the reaction mechanism and initial and final state interactions. We have computed these parameters for several reaction mechanisms, and have explored their dependence on initial and final state interactions. [Preview Abstract] |
Saturday, October 17, 2009 4:00PM - 4:15PM |
LD.00009: Evaluation of the Underlying Event in Pp Collisions at vs = 200 GEV at Star Grant Webb The interpretation of STAR's published inclusive jet cross-section and longitudinal asymmetry data relies on a robust connection between the experimentally measured and theoretically calculated jet energy scale (JES). Evaluation of the underlying event (UE), the isotropic distribution of particles resulting from partonic interactions not associated with the partonic collision producing the jet, is a necessary step in the quantification of the JES in hadronic collisions. This presentation will discuss progress toward the extraction of the UE in $\sqrt{s}=$ 200 GeV proton collisions produced at the Relativistic Heavy Ion Collider (RHIC) and detected in the Solenoidal Tracker at RHIC (STAR). Techniques, developed by the CDF collaboration at Fermilab, are used to isolate and charactertize the UE in dijet events. Comparisons between CDF and STAR results will be evaluated and progress towards quantifying the UE contribution to the JES for jets reconstructed at STAR will be reported. These results facilitate the prediction of underlying event observables at LHC collision energies by providing vital constraints on the center of mass scaling of the UE in pp collisions. [Preview Abstract] |
Saturday, October 17, 2009 4:15PM - 4:30PM |
LD.00010: Topological charge and susceptibility at finite temperature in a random matrix model Munehisa Ohtani Random matrix model is known to describe the chiral phase transition of QCD qualitatively, but at finite temperature it suppresses the topological susceptibility in the thermodynamic limit by the inverse of the volume $V$. We propose a modified model in which the topological susceptibility at finite temperature behaves reasonably. In the microscopic domain of QCD, where the Compton wavelength of the pion is much larger than the size of the box, the quark mass $m$ dependence of the QCD partition function in a fixed topological charge becomes insensitive to the topological charge for $mV\Sigma \gg 1$ with the chiral condensate $\Sigma$ in the chiral limit. Applying this property to a random matrix model at finite temperature, we show that an additional normalization factor is required for the partition function at the fixed topology. We report that the random matrix model with the additional factor to satisfy the universal behavior of the partition function agrees with the modified model to make the topological susceptibility well-defined. [Preview Abstract] |
Saturday, October 17, 2009 4:30PM - 4:45PM |
LD.00011: AdS/QCD Applied to Baryon Structure and Strangeness Changing Currents Carl Carlson We calculate observables such as the electromagnetic form factors of nucleons and their gravitational or energy-momentum form factors (which can be obtained experimentally as moments of the generalized parton distributions) by using an AdS/QCD model, where one considers a Dirac field coupled to a vector field in the 5-dimensional AdS space. We will also comment on how to extend AdS/QCD considerations to include quarks of differing masses, giving results for the $K_{\ell 3}$ form factor as a dynamical example. [Preview Abstract] |
Saturday, October 17, 2009 4:45PM - 5:00PM |
LD.00012: The NJL-jet model for quark fragmentation functions Takuya Ito, Wolfgang Bentz, Ian Cloet, Anthony Thomas, Koichi Yazaki Quark distribution and fragmentation functions are the basic nonperturbative ingredients for a QCD-based analysis of hard scattering processes. We present some results of our recent calculations of quark fragmentation functions to pions in the NJL model. The important point is that our fragmentation functions naturally satisfy the momentum and isospin sum rules without any new parameters into the theory. Our calculation is based on a product ansatz to describe cascade-like fragmentation processes, similar to the product ansatz used in the quark jet-model of Field and Feynman. We arrive at the following expression for the total fragmentation function: \[ \begin{array}{l} D_q^\pi (z)=\sum\limits_{m=1}^N \sum\limits_{k=m}^N {P(k)\int_{\,0}^{\,1} {d\eta _1 } \int_{\,0}^{\,1} {d\eta _2 } \cdots \int_{\,0}^{\,1} {d\eta _k } } \\ \,\,\,\,\,\times \sum\limits_{Q_k } {F_q^{Q_1 } (\eta _1 )F_{Q_1 }^{Q_2 } (\eta _2 )\cdots F_{Q_{k-1} }^{Q_k } (\eta _k )} \delta (z-z_m )\delta (\tau _\pi ,(\tau _{Q_{m-1} } -\tau _{Q_m } )/2)\,\,. \\ \end{array} \] We present numerical results and compare with the empirical results. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory. [Preview Abstract] |
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