Related papers: Four-quark stability
The classical quenched quark models with three constituent quarks provide a good description for the baryon spatial ground states, but fail to reproduce the spectrum of baryon excited states. More and more evidences suggest that unquenched…
Progress in charm physics has been prodigious over the last twenty years; it comes both from fixed target and collider experiments, and can guide us toward future investigations. To fully exploit the power of flavor physics, complications…
We review the chromoelectric and chromomagnetic mechanisms that tentatively lead to stable or metastable multiquark configurations. An alternative interpretation of the dynamics is the quark interchange between hadrons, as illustrated in…
Exotic charmonium and bottonomium resonances recently discovered are discussed and interpreted as diquark-antidiquark states containing a pair of charm quarks and a pair of light, up and down, quarks. Successes, shortcomings and predictions…
In this talk I would like to discuss two aspects of charm physics. One is to show that many standard model predictions for rare decay modes (along with $D^0 -\bar{D}^0$ mixing and CP violation) are extremely small thus opening a window for…
We review several key aspects of charm phenomenology which are important for the general program of determination of matrix elements of the Cabbibo-Kobayashi-Maskava (CKM) matrix. We argue that charm physics plays an important role in…
We study possible multiquark contributions to the charm baryon spectrum by considering higher order Fock space components. For this purpose we perform two different calculations. In a first approach we do a coupled-channel calculation of…
Using the experimental data on pentaquarks with a hidden charm, new upper limits on the intrinsic charm in the proton are obtained, possible shapes of heavy quark distributions inside the proton are discussed.
New results from charm experiments have led to renewed interest in this physics. The charm sector is now seen as a powerful tool to search for new physics and to advance our understanding of the standard model. We owe much of this progress…
We present a generalization of the hyperspherical harmonic formalism to study systems made of quarks and antiquarks of the same flavor. This generalization is based on the symmetrization of the $N-$body wave function with respect to the…
A simple string model inspired by the strong-coupling regime of Quantum ChromoDynamics is used as a potential for studying the spectrum of multiquark systems with two quarks and two antiquarks, with a careful treatment of the four-body…
The role of charm in testing the Standard Model description of quark mixing and CP violation through measurements of lifetimes, decay constants and semileptonic form factors is reviewed. Together with Lattice QCD, charm has the potential…
The hidden-charm tetraquarks with strangeness, $c\bar{c}s\bar{q}$ $(q=u,\,d)$, in $J^P=0^+$, $1^+$ and $2^+$ are systematically investigated in the framework of real- and complex-scaling range of a chiral quark model, whose parameters have…
We consider the prospect of using the charm system as a laboratory for probing new physics. The theoretical expectations for rare charm meson decays, $D^0-bar D^0$ mixing, and charm quark asymmetries in $Z$ decays are examined in the…
A review is presented of past and recent attempts to build multiquark states within current models already describing ordinary mesons and baryons. This includes: coherence in the chromomagnetic interaction, tetraquarks with two heavy…
By assigning the narrow scalar resonance (which has been recently observed at the B-factories) to one of iso-triplet four-quark mesons containing a charm quark, two body decays of the four-quark mesons are studied. It is predicted that some…
We present an exact method to study four-quark systems based on the hyperspherical harmonics formalism. We apply it to several physical systems of interest containing two heavy and two light quarks using different quark-quark potentials.…
In the first part I briefly survey recent issues in constituent quark models raised by the observation of unusual hadronic states. In particular I discuss the role of higher Fock components in the wave function of baryons and the possible…
Charm spectroscopy has studied under a string model. Charmed baryons are composed of diquark and charm quark which are connected by a constant tension. In a diquark picture, the quantum numbers $J^P$ of confirmed baryons are well assigned.…
We give a brief review of developments in the field of exotic hadrons formed of more than three quarks and/or antiquarks. In particular we discuss the stability of multiquark systems containing heavy flavours. We show that the gluon…