The Exo(tic) Had(ron) Collaboration started in 2023 to explore all aspects of exotic hadron physics, from predictions within lattice QCD, through reliable extraction of their existence and properties from experimental data, to descriptions of their structure within phenomenological models.
News
Read allRadiative transitions of hybrid mesons
Eric Swanson (Co-PI, University of Pittsburgh) and Shahriyar Jafarzade (ExoHad postdoc, University of Pittsburgh) have investigated how hybrid mesons (particles containing a quark-antiquark pair and an excited gluonic field) decay into ordinary mesons by emitting a photon. Their new study examines the lowest charmonium-hybrid multiplet using a constituent-gluon model based on Coulomb-gauge QCD.
A central finding is the importance of a previously overlooked leading “seagull” interaction, which Read more
S-matrix informed neural networks
Wyatt A. Smith (LBNL, U. California Berkeley, William & Mary, Messina U., ExoHad postdoc), Arkaitz Rodas (ODU & JLab, co-PI), Marius D. Thomas (U. California Berkeley), César Fernández-Ramírez (UNED, co-PI), Giorgio Foti (Messina U., ExoHad PhD student), Lin Qiu (ODU, ExoHad postdoc), Adam P. Szczepaniak (Indiana U. & JLab, co-PI), and Alessandro Pilloni (Messina U. & INFN Catania, co-PI) from the Joint Physics Analysis Center studied low-energy pion scattering by replacing fixed Read more
First observation of an exotic Reggeon
This newly submitted paper reports the first observation of an exotic Reggeon in high-energy scattering by the COMPASS experiment at CERN.
ExoHad researchers César Fernández Ramírez (UNED, co-PI), Giorgio Foti (Messina U., ExoHad PhD student), Nadine Hammoud (Barcelona U., ExoHad postdoc), Vincent Mathieu (Barcelona U., co-PI), Gloria Montaña (Barcelona U., ExoHad postdoc), Robert J. Perry (MIT, ExoHad postdoc), Alessandro Pilloni (Messina U. & INFN Catania, co-PI), Arkaitz Rodas (ODU & Read more
First determination of vector and tensor couplings from polarized $\pi\Delta$ photoproduction
Coupling constants encode the underlying dynamics of the interacting hadrons and their determination forms a central goal of hadron physics. Many such couplings cannot be extracted from decay widths because the corresponding decays are kinematically forbidden.
Of these, the coupling of $N\Delta$ to mesons are of special interest due to their applications in a wide variety of studies. High-energy polarized photoproduction offers an alternative route, where these couplings appear as residues of Read more
Lattice QCD analysis of the H-dibaryon including left-hand-cut effects
Understanding exotic matter, composed of states that go beyond the conventional quark-antiquark and three-quark pictures, is a central goal of modern hadron physics. Lattice QCD offers a first-principles path to study these systems through finite-volume spectra, which can be related to scattering amplitudes. For several exotic candidates, long-range exchange mechanisms produce left-hand-cut branch points in the amplitudes close to the relevant energy region, requiring methods that incorporate Read more