Conveners
Hadron spectroscopy and exotics
- Ryan Mitchell (Indiana University)
- Andrew Jackura (Old Dominion University & Jefferson Lab)
- Karin Schönning (Department of Physics and Astronomy, Uppsala University, Sweden)
Hadron spectroscopy and exotics
- Karin Schönning (Department of Physics and Astronomy, Uppsala University, Sweden)
- Andrew Jackura (Old Dominion University & Jefferson Lab)
- Ryan Mitchell (Indiana University)
Description
Information for speakers about talk's duration:
20 min slot = 15 to speak + 5 for questions
Due to the high production of light mesons J/ψ radiative and hadronic decays, the largest sample of J/ψ events accumulated at the BESIII detector offers a unique laboratory to study the light mesons spectroscopy and search for the light exotic states. In this talk, we shall report the recent progresses on the light meson spectroscopy achieved at BESIII.
The $\pi^-p\to\pi^-\eta p$ and $\pi^- p\to\pi^-\eta^\prime p$ reactions were recently studied by the COMPASS collaboration at CERN. The analysis has shown that for high energies the $\pi\eta^{(')}$ system is produced in two kinematic regimes. In these regimes the laboratory frame direction of $\eta^{(')}$ is either forward or backward. The Gottfried-Jackson frame analysis of the polar angle...
KLOE and KLOE-2 experiment, operated at the DA$\Phi$NE facility of Frascati, acquired almost 8 fb$^{-1}$ of data at the $\phi$ peak resonance.
The two samples together represent the largest statistics ever collected at an $e^+ e^-$ collider at 1.02 GeV center-of-mass energy.
With about 2.4 $\times 10^{10} \,\phi$ and $3.1 \times 10^8 \,\eta$ meson events available for data analysis, ...
I will present the recent studies by the Joint Physics Analysis Center on the tools to extract information about the excited hadron spectrum from data.
The large data sample accumulated by the Belle experiment at the KEKB asymmetric-energy e^{+} e^{-} collider provides a unique opportunity to perform studies related to hadron spectroscopy utilising various production mechanisms. We studied the two-photon process \gamma\gamma \to \gamma\psi(2S) is studied for the first time and found an evidence for a structure in the \gamma\psi(2S)...
We study several chiral Lagrangians that describe the two- and three-body decays of a pseudoscalar glueball, $J^{P C} = 0^{−+}$, with a mass of $2.6$ GeV and its first excited state with a mass of $3.7$ GeV. Their masses were predicted by lattice QCD simulations. We compute the decay of the pseudoscalar glueball into (pseudo)scalar and (axial-)vector mesons as well as their excited states. We...
In e+e- collisions between 2 and 3 GeV, excited states of rho, omega and phi can be produced directly. Especially the resonances around 2GeV like rho(2000), rho(2150) and \phi(2170) are not fully understood yet. Theorists describe the phi(2170) as a traditional s s-bar state, an s s-bar g hybrid, a tetraquark state, a Lambda Lambda-bar bound state, or a phi KK resonance. The predicted decay...
We extend previous work concerning rest-frame partial-wave mixing in Hamiltonian effective field theory to both elongated and moving systems, where two particles are in a periodic elongated cube or have nonzero total momentum, respectively. We also consider the combination of the two systems when directions of the elongation and the moving momentum are aligned. This extension should also be...
The GlueX experiment conducts searches for hybrid mesons, using a linearly polarized photon beam, impinging on a liquid hydrogen target. The GlueX detector provides a close to $4\pi$ acceptance and allows to reconstruct both, neutral and charged particle tracks which are produced in the $\gamma p$ reactions.
GlueX is taking data in two phases and has collected $\sim8.4\,\rm{PB}$ of raw...
The world’s largest sample of J/ψ 1.3 billion events accumulated at the BESIII dector offers a unique opportunity to study light meson decays. In recent years the BESIII experiment has made significant progresses in eta/eta' decays, including observation of eta'->pi+pi- mu+mu-, search for the rare decays of eta’->4pi0 and eta’->gam gam eta as well as the search for CP violation in eta’->pi+pi-...
The hadron spectrum is tangled with threshold and triangle singularities
that difficult the identification of actual resonance states.
We present a thermal-field theory computation in the late hadron stage
of the fireball. Our finding is that such singularities can be filtered
by comparing other data to heavy ion collisions:
peaks therein seem more likely to be hadrons than rescattering...
Although the charmonium spectrum seems to be well investigated, charmonia can still be used as benchmarks to test our QCD predictions, as these states lay in the transition region between perturbative and non-perturbative QCD.Despite the need for experimental confirmations, setbacks arise from limited statistics because of the production processes of all non-vector states. The
properties and...
After examining the Feynman diagrams corresponding to some candidates of hadronic molecular states, we propose a possible binding mechanism induced by shared light quarks. This mechanism is similar to the covalent bond in chemical molecules induced by shared electrons. We use the method of QCD sum rules to calculate its corresponding light-quark-exchange diagrams, and the obtained results...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is an upgrade of the B factory facility at KEK in Tsukuba, Japan. The experiment began operation in 2019 and aims to record a factor of 50 times more data than its predecessor. Belle II is uniquely capable of studying the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First...
In this talk recent XYZ results at BESIII will be reviewed, that includes: Observation of a near-threshold enhancement in the Lambda Lambda-bar mass spectrum from e+ e- -> phi Lambda Lambda-bar at the center-of-mass energies from 3.51 to 4.60 GeV; Observation of e+ e- -> eta psi(2S) at the center-of-mass energies from 4.236 to 4.600 GeV; Cross section measurement of e+ e- -> p pbar eta and e+...
I'll present estimations of cross sections for the electro- and photoproduction of several exotic candidates, including X(3872), Y(4260) and Z_c(3900)+ based on the publication 10.1103/PhysRevD.102.114010.
I also present preliminary results of the inclusive photoproduction of these exotic meson candidates.
In the last ten years, a whole set of new particles not fitting in the constituent quark model has populated the mass region above the
open-charm threshold. The spectrometer BESIII, installed at the Beijing Electron Positron Collider II, can access these states in electron-positron annihilations both by production and by direct formation. It has collected a large dataset at different...
Most of hadrons consist of two or three quarks and they are called mesons and baryons. Those which are not classified into mesons and baryons are called exotic hadrons. The exotic hadrons are considered as, for instance, multiquark states with more than three quarks, or hadronic molecular states which are weakly bound states of hadrons. Many candidates for exotic hadrons are discovered in...
Recent results by the CMS experiment in the hadron spectroscopy field will be discussed. In conventional spectroscopy are included results concerning the excited Lambda_b, Xi_b and B_c states, whereas the exotic one includes searches for YY* states and the production of the X(3872) observed in a new B0s meson decay and evidenced in PbPb collisions.
Precision hadron spectroscopy helps in understanding how the matter is made around us. The large data sample accumulated by the Belle experiment at the KEKB asymmetric-energy $e^{+}e^{-}$ collider provides us a unique opportunity to perform these studies. We report recent results on charmed baryon spectroscopy from Belle, which include a study on the spin and parity of $\Xi_{c}(2970)$, mass...
The study of the nucleon excitation spectra allows to better understand the dynamics of the constituents inside the nucleons. Large discrepancies exist between experimentally observed states and predicted states from lattice QCD calculations or from phenomenological quark models. Experimentally, the nucleon excitation spectra can be investigated by studying different meson photoproduction...
We developed a deep neural network (DNN) to determine the pole configuration of a coupled-channel scattering with near-threshold enhancement. The trained DNN takes the partial wave amplitude as input and gives the number of nearby poles in any of the unphysical sheets. To avoid any possible model bias, we generate a training dataset using an S-matrix where the relevant pole parameters are...
A study of J/psi p resonances in the Lambda_b -> J/psi p K decays with large m(pK) invariant masses is presented by the ATLAS experiment at the LHC. The analysis is based on a combined sample of pp collision data at centre-of-mass energies of 7 TeV and 8 TeV corresponding to integrated luminosities of 4.9 fb-1 and 20.6 fb-1, respectively. Although the data prefer the model with two or more...
