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Study on $N\bar{N}$ $S$-wave Elastic Cross Section and Possible Bound States Within a Constituent Quark Model  [PDF]
Hourong Pang,Jialun Ping,Fan Wang
Physics , 2007, DOI: 10.1088/0256-307X/25/9/027
Abstract: In the framework of a chiral constituent quark model, considering the contributions of $\pi$ annihilation and one-gluon annihilation, the proton-antiproton $S$-wave elastic scattering cross section experimental data can be reproduced by adjusting properly one-gluon annihilation coupling constant. Meanwhile, using the fixed model parameter, we do a dynamical calculation for all possible $S$-wave nucleon-antinucleon states, the results show that, there is no $S$-wave bound state as indicated by a strong enhancement at threshold of $p\bar{p}$ in $J/\psi$ and $B$ decays.
Study of $p\barΛ$ and $p\barΣ$ systems in constituent quark models  [PDF]
Hongxia Huang,Jialun Ping,Fan Wang
Physics , 2011, DOI: 10.1142/S0217732312500393
Abstract: The $p\bar{\Lambda}$ systems with J=0 and J=1 are dynamically investigated within the framework of two constituent quark models: the chiral quark model and the quark delocalization color screening model. The model parameters are taken from our previous work, which gave a good description of the proton-antiproton S-wave elastic scattering cross section experimental data. The $p\bar{\Lambda}$ elastic scattering processes with coupling to $p\bar{\Sigma}$ state are studied. The results show that, there is no s-wave bound state as indicated by an enhancement near the threshold of $p\bar{\Lambda}$ in $J/\psi$ decay. However, a $IJ = {1/2}0$ $p\bar{\Sigma}$ resonance state is given in the quark delocalization color screening model.
N ˉN S-Wave Elastic Cross Section and Possible Bound States in a Constituent Quark Model

PANG Hou-Rong,PING Jia-LunWANG Fan,

中国物理快报 , 2008,
Abstract:
Do $c\bar c n\bar n$ bound states exist?
Vijande, J.;Weissman, E.;Barnea, N.;Valcarce, A.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.76.094022
Abstract: The four--quark system $c\bar c n\bar n$ is studied in the framework of the constituent quark model. Using different types of quark-quark potentials, we solve the four--body Schr\"odinger equation by means of the hyperspherical harmonic formalism. Exploring the low laying $J^{PC}$ states for different isospin configurations no four-quark bound states have been found. Of particular interest is the possible four-quark structure of the X(3872). We rule out the possibility that this particle is a compact tetraquark system, unless additional correlations, either in the form of diquarks or at the level of the interacting potential, not considered in simple quark models do contribute.
Do $c\bar c n\bar n$ bound states exist?  [PDF]
J. Vijande,E. Weissman,N. Barnea,A. Valcarce
Physics , 2007, DOI: 10.1103/PhysRevD.76.094022
Abstract: The four--quark system $c\bar c n\bar n$ is studied in the framework of the constituent quark model. Using different types of quark-quark potentials, we solve the four--body Schr\"odinger equation by means of the hyperspherical harmonic formalism. Exploring the low laying $J^{PC}$ states for different isospin configurations no four-quark bound states have been found. Of particular interest is the possible four-quark structure of the X(3872). We rule out the possibility that this particle is a compact tetraquark system, unless additional correlations, either in the form of diquarks or at the level of the interacting potential, not considered in simple quark models do contribute.
The role of $qqqq\bar{q}$ components in the nucleon and the N(1440) resonance  [PDF]
B. Julia-Diaz,D. O. Riska
Physics , 2006, DOI: 10.1016/j.nuclphysa.2006.09.016
Abstract: The role of $q\bar q$ components in the nucleon and the N(1440) resonance is studied by explicit coupling of the lowest positive parity $qqqq\bar q$ state to the $qqq$ components in the harmonic oscillator quark model. The lowest energy $qqqq\bar q$ component, where the 4-quark subsystem has the flavor-spin symmetry $[4]_{FS}[22]_F[22]_S$, is close in energy to the lowest positive parity excitation of the nucleon in the $qqq$ quark model. The confining interaction leads to a strong mixing of the $qqqq\bar q$ system and the positive parity excited state of the $qqq$ system. This result is in line with the phenomenological indications for a two-component structure of the N(1440) resonance. The presence of substantial $q\bar q$ components in the N(1440) can bring about a reconciliation of the constituent quark model with the large empirical decay width of the N(1440).
Studying the $ωN$ elastic and inelastic cross section with nucleons  [PDF]
Ye. S. Golubeva,W. Cassing,L. A. Kondratyuk,A. Sibirtsev,M. Büscher
Physics , 1999, DOI: 10.1007/PL00013602
Abstract: We explore the possibility to measure the elastic and inelastic $\omega N$ cross section in $p{+}d{\to}d{+}\omega{+}p_{sp}$ and $p{+}A$ reactions. Our studies indicate that the elastic scattering cross sections can be determined for $\omega$ momenta above 1 GeV/c in $p{+}d$ reactions by gating on high proton spectator momenta whereas the $\omega N$ absorption cross section down to low relative $\omega$ momenta is most effectively studied in $p{+}A$ reactions at beam energies 2.0--2.7 GeV
The contributions of $qqqq\bar{q}$ components to the axial charges of proton and its resonances  [PDF]
S. G. Yuan,C. S. an,Jun He
Physics , 2009, DOI: 10.1088/0253-6102/54/4/22
Abstract: We calculate the axial charges of the proton and its resonances in the framework of the constituent quark model, which is extended to include the $qqqq\bar{q}$ components. If 20% admixtures of the $qqqq\bar{q}$ components in the proton are assumed, the theoretical value for the axial charge in our model is in good agreement with the empirical value, which can not be well reproduced in the traditional constituent quark model even though the $SU(6) \bigotimes O(3)$ symmetry breaking or relativistic effect is taken into account. We also predict an unity axial charge for $N^{*}(1440)$ with 30% $qqqq\bar{q}$ components constrained by the strong and electromagnetic decays.
$N\bar D $ system: A challenge for $\bar {\rm P}$ANDA  [PDF]
T. F. Carames,A. Valcarce
Physics , 2012, DOI: 10.1103/PhysRevD.85.094017
Abstract: We study the $N \bar D$ system by means of a chiral constituent quark model. This model, tuned in the description of the baryon and meson spectra as well as the $NN$ interaction, provides parameter-free predictions for the charm -1 two-hadron systems. The presence of a heavy antiquark makes the interaction rather simple. We have found sharp quark-Pauli effects in some particular channels, generating repulsion, due to lacking degrees of freedom to accommodate the light quarks. Our results point to the existence of an attractive state, the $\Delta \bar D^*$ with $(T,S)=(1,5/2)$, presenting a resonance close to threshold. It would show up in the scattering of $\bar D$ mesons on nucleons as a D wave state with quantum numbers $(T)J^P=(1)5/2^-$. This resonance resembles our findings in the $\Delta\Delta$ system, that offered a plausible explanation to the cross section of double-pionic fusion reactions through the so-called {\it ABC} effect. The study of the interaction of $D$ mesons with nucleons is a goal of the $\bar {\rm P}$ANDA Collaboration at the European facility FAIR and, thus, the present theoretical study is a challenge to be tested at the future experiments.
Parametrization of the $\bar PP$ Elastic Scattering Differential Cross Section Between 2 GeV/c $\leq P_{lab}\leq$ 16 GeV/c
Galoyan, A.;Ritman, J.;Sokolov, A.;Uzhinsky, V.
High Energy Physics - Phenomenology , 2008,
Abstract: A parameterization of the $\bar pp$ differential elastic scattering cross section in the beam momentum range from 2 to 16 GeV/c is proposed. The parameterization well describes the existing data including the observed diffraction pattern at four-momentum transfer $|t|$ up to 1.5-2.0 GeV$^2$. It can be used for detailed calculations of the radiation load on the detectors being designed for the PANDA detector at the future FAIR facility in Darmstadt.
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