The study of the spectrum of hadrons provides important insights into the interaction of the strong force. Photoproduction experiments play a key role in these investigations and are used in the search for hadrons with both conventional as well as exotic quantum numbers, such as mesons with gluonic degrees of freedom.
The GlueX experiment at Jefferson Lab, features a 9 GeV linearly polarized...
Recently structures in invariant mass distributions and excitation energy spectra have been attributed to triangular singularities as discussed in e.g.,[1,2] and in the review by Guo et al. [3]. These singularities emerge under specific kinematic conditions when new reaction channels open up. It will be shown that a triangular singularity associated with the opening of the γ p →p a0 → p π0...
Using the world’s largest samples of $J/\psi$ and $\psi(3686)$ events produced in $e^+e^-$ annihilation, BESIII is uniquely positioned to study light hadrons in radiative and hadronic charmonium decays. In particular, exotic hadron candidates including multiquark states, hybrid mesons and glueballs can be studied in high detail. Recent highlights from the light hadron spectroscopy program,...
We make predictions for the production and decays of X(2900) states, and their possible charged partners, in B+ and B0 decays, considering a number of competing models for the states, including triangle diagrams mediated by quark exchange or pion exchange, and resonance scenarios including molecules and tetraquarks. Assuming only isospin symmetry and the dominance of color-favored weak decays,...
A `second charm revolution' was sparked with the discovery of new
'XYZ' states, such as the $X(3872)$ or the $Y(4260)$ by the B factories
Belle and BABAR. These states do not fit into the conventional
picture of quark-antiquark bound systems. A number of further,
non-conventional bound states have been discovered in different
production processes at several experiments.
This talk...
J/ψ near threshold photoproduction plays a key role in the physics program at the Thomas Jefferson National Accelerator Facility (JLab) 12 GeV upgrade due to the wealth of information it has to offer. J/ψ photoproduction proceeds through the exchange of gluons in the t-channel and is expected to provide unique insight about the nucleon gravitational form factors and the nucleon mass radius....
Lattice QCD provides a means to rigorously compute hadronic scattering amplitudes within which hadron resonances appear. I'll show examples of the determination of resonances (non-exotic, exotic and possibly exotic) in coupled-channel situations, and illustrate how, by coupling scattering systems to external currents, we can study production mechanisms and explore resonance internal structure.
As a unique probe to low-energy properties of the strong interaction, exotic hadrons are of great interest in both theoretical and experimental communities. In recent years, LHCb have discovered dozens of such particles, providing fruitful inputs to the theoretical studies of the exotic hadron spectroscopy. The story is still going on, and some latest results about exotic hadrons from LHCb are...
I will discuss lattice QCD results on various tetraquarks with two heavy quarks or a heavy quark and an antiquark. This will include the doubly charm tetraquark and charmonium-like channels, which are of current experimental interest.
A comprehensive picture of the strong interaction can be obtained by extending our currently well understood nucleon-nucleon (NN) interaction to interactions involving strangeness degrees of freedom. The short lifetime of hyperons, however, prevents high-precision scattering experiments using typical procedures, and our efforts have been focused on complementary approaches utilising...
Whereas exotic states observed in charm and beauty sectors appear as narrow resonances near particle thresholds constituting thus weakly bound systems of molecular character, such systems have to appear in the non-flavored sector as broad resonances, since the decay products themselves constitute very broad resonances. This complicates enormously their detection despite the fact that...
The discoveries of the pentaquark states and $XYZ$ mesons in the charmed quark sector initiated a new epoch in hadron physics, where the existence of exotic multi-quark states beyond the conventional three and two quark systems has been unambiguously realised. Similar structure may be evidenced in the light, $uds$ sector in meson photoproduction, where access to a low momentum exchange and...
A search for low-mass structures in the J/psiJ/psi mass spectrum produced by proton-proton collisions at sqrt(s) = 13 TeV is performed at the CMS experiment. The data sample corresponds to an integrated luminosity of 135 fb^-1 collected by the CMS at the CERN LHC. The previously observed X(6900) by LHCb is confirmed in this study, and a new structure at a lower mass is observed. Both...
I will give an update on our work studying antiheavy-antiheavy-light-light four-quark states using lattice QCD. We consider the three different tetraquark candidates $ \bar{b}\bar{b}ud $, $ \bar{b}\bar{b}us $ and $ \bar{b}\bar{c}ud $ and search for possible existing bound states or resonances in all channels. In addition to commonly used local interpolating operators we also employ scattering...
We will discuss model prediction for inclusive and exclusive XYZ production at JLab and at the EIC from the publications
10.1103/PhysRevD.102.114010
10.1103/PhysRevD.106.094009
Physicists investigate the subatomic world by bombarding their subject of study with a hail of tiny subatomic “bullets”. From the way these “bullets” bounce off their target one can infer a wealth of detailed information about the target’s structure. Different kinds of subatomic “bullets” probe different aspects of the target, certain important aspects of the force holding atomic nuclei...
I will discuss the recent results from JLab on J/\psi photo production and prospects and expectations for exotic charmonia at future photon-/lepton- machines
I will discuss the scalar and axial-vector charmed mesons, including the Ds0(2317), Ds1(2460) and their nonstrange partners. I will show that the hadronic molecular picture for these states is consistent with existing lattice results and LHCb measurements. Predictions on the decays of the Ds0 and Ds1 as well as properties of their bottom partners will be made.
In this talk, I will discuss new results in the charm/bottom baryon sectors, including discoveries of new excited open-flavor baryons with the LHCb experiment, analyses of their properties, and development of the analysis techniques.
It is natural to classify baryonic excitation multiplets by quantum numbers of the light diquark in the ground configuration, which is $0^+$, referred to the...
Singly and doubly spin $1/2$ charmed baryons are investigated at multiple temperatures using the anisotropic FASTSUM 'Generation 2L' lattice QCD ensembles. We discuss the temperature dependence of these baryons' spectrum in both parity channel with a focus on the confining phase. We use fit independent methods to determine when a traditional fiting procedure and mass determination is...
Exotic spectroscopy is a hot topic since there are several discoveries or observations per year. In this review talk, the last main experimental discoveries will be presented and then the main theoretical interpretations will be discussed. Finally, some results of which I am also one of the authors will be presented and discussed.
The search for chargeless nuclei consisting only of neutrons has been a long-lasting challenge in nuclear physics, dating more than six decades back (see Ref. [1] for a recent review). The tetraneutron, in particular, has attracted a lot of experimental and theoretical attention. Most models agree that nuclear forces cannot bind four neutrons together without destroying many of the other...
