Coordinatori
Parallel 1: Hyperon production with electromagnetic probes
- Paolo Levi Sandri
Parallel 1: Baryon structure through meson electroproduction, transition form factors, and time-like form factors
- Volker Crede
Parallel 1: Baryon resonances in experiments with hadron beams and in the e+e- collisions
- Stefano Spataro (Istituto Nazionale di Fisica Nucleare)
Parallel 1: QCD calculations of hadrons spectrum and structure
- Gernot Eichmann
Parallel 1: Polarization observables photo- and electro-production of mesons off nucleons
- Philip Cole
Descrizione
Hyperon production with electromagnetic probes
The Mainz Microtron (MAMI), operated by the Institute for Nuclear Physics at the Gutenberg University Mainz, provides unpolarized and polarized electron beams of up to 1604 MeV energy. These beams have been used in the multi-spectrometer facility (called A1) to probe kaon electro-production reactions including studies of hypernuclei. In parallel, studies of photo-induced kaon production...
The discoveries of the pentaquark, $P_C$, states and $XYZ$ mesons in the charmed quark sector initiated a new epoch in hadron physics. The existence of exotic multi-quark states beyond the conventional $\textit{q$\overline{q}$}$ and $\textit{qqq}$ systems has obviously been realised. Such states could manifest as single colour bound objects, or evolve from meson-baryon and meson-meson...
New models for photo- and electroproduction of kaons on the proton were constructed [1,2,3] utilizing new experimental data from LEPS, GRAAL, and particularly CLAS collaborations. The higher spin nucleon (spin-3/2 and spin-5/2) and hyperon (spin-3/2) resonances were included using a consistent formalism and they were found to play an important role in the data description. In these analyses,...
The study of electromagnetic transitions opens a window into the very nature of the strong interaction. And, indeed, such a study of how a ground-state nucleon transitions to an excited state, over a broad range of $q^2$, will provide keen insight into the evolution of how dynamically-generated masses emerge from the asymptotically-free, nearly massless quarks of perturbative QCD as well as...
During the past several decades a large quantity of high-quality mesonic photo- and electroproduction data of have been measured at electromagnetic facilities worldwide. By contrast, meson-beam data for these same final states are mostly outdated, largely of poorer quality, or even non-existent. Thus existing meson beam results provide inadequate input to interpret, analyze, and exploit the...
In 2010, high-precision studies of muonic hydrogen found notably smaller values for the charge radius than earlier results that have been extracted from elastic electron-scattering data and through the spectroscopy of atomic hydrogen. The MUon Scattering Experiment (MUSE) at the Paul Scherrer Institute (PSI) has been developed to address this so-called proton-radius puzzle. The experiment will...
At J-PARC, we built a large acceptance time-projection chamber, named Hyp-TPC, for various studies on baryons. Especially, E45 experiment will study exotic nucleon/Delta resonances via $p(\pi,2\pi)$ reactions. We will also introduce the other experiments with Hyp-TPC, namely:
- H-dibaryon search (E42)
- Exotic hyperon resonance search (E72)
- $\Sigma N$ cusp study with $d(K^-,\pi^-)$ reaction
The High Acceptance Di-Electron Spectrometer (HADES) [1], installed at GSI Helmholtzzentrum in Darmstadt, was designed for spectroscopy of positron-electron pairs with excellent purity and mass resolution. The experimental program of HADES focuses on two main goals: (I) measurements of dielectron emission of a compressed baryonic matter formed in 1-2 AGeV heavy-ion collisions and investigate...
The pion-nucleus reaction is an important source of information about hadronic matter. At incident momenta below 2 GeV/c, it gives access in a very unique way to the properties of baryonic resonances in the nuclear medium. While the region of the Δ(1232) resonance, corresponding to incident pion beam momenta of about 300 MeV/c, was studied in detail in the past, only very scarce measurements...
Recent Belle II results on charmed baryon lifetimes are presented. In addition prospects for other baryon analyses expected to be performed using Belle II data in the future are reviewed.
I will review recent progress in lattice QCD calculations of the hadron spectrum, with a focus on baryonic resonances. The talk will highlight formal progress in extracting various multi-hadron amplitudes as well as recent numerical results. In the presentation I will highlight key challenges faced by lattice calculations, e.g. due to the restriction to a Euclidean finite-volume spacetime. I...
I report on a pilot lattice simulation to study hadronic parity violation with lattice QCD, in particular
to calculate the $P$-odd long-range pion-nucleon coupling $h_\pi^1$.
I discuss the implementation of a recently proposed new approach, where the parity-violating Lagrangian
is mapped to a $P$-conserving one, based on the PCAC relation, and the coupling $h_\pi^1$
is extracted from...
The observation that neutrinos can oscillate from one flavour to another suggests that these elementary particles have a very small but non-zero mass. The weak cross sections that occur in the neutrino oscillation experiments are parametrized among other things by the nucleon axial and vector form factors, which can be computed via lattice QCD simulations. In this talk, I will highlight the...
We present results for the heavy baryon spectrum for ground and excited states with quantum numbers $J^P = 1/2^+$ and $3/2^+$ using functional methods in QCD. To this end, we reduce the three-quark Faddeev equations to two-body equations via the quark-diquark approach, where the baryons are treated as bound states of quarks and effective diquarks. The resulting Bethe-Salpeter equation amounts...
Exploring the low energy region of QCD requires a detailed study of the nucleon resonances and their decays. Analysing the excitation spectrum of (quasi-) free nucleons is essential to establish a baseline for comparisons with in-medium modifications. Of particular interest are the mixed-charged channels of double-pion photoproduction, as they are sensitive to sequential decays of $\Delta$...
Although many more cascade resonances than established are expected from quark models and QCD calculations, experimental evidence of most of them have been rather weak. With increased beam energy and luminosity now available at CLAS12, it is possible to search for excited cascades using quasi-real photoproduction as well as electroproduction using the CLAS12 spectrometer and probe their...
