Elucidation of New Hadrons with a Variety of Flavors


Research Project B01: Elucidation of baryons with unusual quark configuration

Research goal

Pentaquark state / Molecular-type meson-baryon resonanceWe are comprehensively measuring the production and decay of exotic baryons such as pentaquark Θ+, consisting of five or more quarks, and Λ(1405) which is a candidate of molecular-type meson-baryon resonances containing s quark, in order to clarify the properties (mass, decay width, internal degree of freedom(spin, isospin, parity)) of these exotics. Through hitherto-unidentified exotic states of hadrons, we are finding a new picture of hadron formation beyond that of the simple quark model. Furthermore, we are enriching our understanding of the constituent quarks of hadrons, as well as the quark-antiquark and quark-quark correlations so that we can better understand the quark confinement and mass generation mechanism of hadrons.

Research techniques and topics

We are comprehensively measuring and investigating the production and decay of exotic baryons to explore new hadronic states with polarized photon beams provided by the Laser Electron Photon beam line facility at SPring-8 (LEPS) and hadron beams provided by J-PARC. Because the coupling strengths of exotic hadrons to the production and decay channels depend on the properties of the hadrons, use of different beams, introducing different kinematics and internal degrees of freedom to the reaction process, is particularly useful for identifying the properties of exotic hadrons.

In this research project, we are working on the following topics:

  1. Conducting exotic hadron spectroscopy experiments utilizing photon beams at LEPS.
  2. Upgrading photon beam intensity to enhance experimental efficiency. Raising photon beam energy to expand hadron production channels and achieve higher controllability on spin, isospin, and parity.
  3. Constructing a large acceptance hadron spectrometer system covering entire angle and momentum regions in order to detect all the decay particles relating to the targeted exotic hadrons. We are planning to move the E949 detector at Brookhaven National Laboratory (BNL) to construct the system.
  4. Developing a new high-speed data acquisition system to accommodate the beam and detector upgrade.
  5. Conducting production and decay spectroscopy experiments of Θ+ and Λ(1405) utilizing low energy kaon beams at J-PARC.
  6. Developing low emittance, high polarization, and high intensity photon beams for LEPS2 project.

Related link: LEPS - Laser Electron Photon Experiment at SPring-8

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Research on pentaquarks with laser electron photon beams Research on pentaquarks with kaon beams
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