7–11 Nov 2022
Seville
Europe/Madrid timezone

Baryon Spectroscopy at GlueX

Not scheduled
20m
Seville

Seville

Universidad Pablo de Olavide, de Sevilla, Ctra. de Utrera, km. 1 41013, Sevilla
Invited/Leading contribution New Facilities and instrumentation

Speaker

Volker Crede (Florida State University)

Description

High-energy electrons and photons are a remarkably clean probe of ha-
dronic matter, essentially providing a microscope for examining atomic nu-
clei and the strong nuclear force. One of the most striking phenomena of
Quantum Chromodynamics (QCD) is the formation of the nucleon out of
massless gluons and almost massless quarks. This system of confined quarks
and gluons serves as the basic constituent of ordinary baryonic matter and
exhibits the characteristic spectra of excited states, which are sensitive to the details of quark confinement. Complementary to nucleon structure studies in deep inelastic scattering experiments, nucleon excitations provide the unique opportunity to explore the many aspects of non-perturbative QCD.

While the last few years have seen significant progress toward the mapping
of the nucleon and ∆ spectrum, experimental information on the spectrum,
structure, and decays of strangeness -2 Ξ baryons remains sparse compared
to non-strange and strangeness -1 baryons. Moreover, the photoproduction
mechanism for these so-called Cascade resonances is not well understood and expected to proceed via highly excited intermediate singly strange hyperons in reactions such as γp → K Y ∗ (Λ ∗ , Σ ∗ ) → KK Ξ (∗) .
The GlueX experiment in Hall D at Jefferson Lab has accumulated high-
statistics samples of photoproduction data in recent years. Since the lowest-lying Cascade states are expected to have narrow widths (as compared to the broad and overlapping N ∗ states), GlueX will be able to shed more light on the systematics of the spectrum of excited states and their properties. Copious data for excited strangeness -1 baryons have also been collected with GlueX, e.g. for the Λ(1405) and Λ(1520), along with the data for Cascade baryons in this experimental hyperon program. In this talk, I will discuss preliminary GlueX results on photoproduced Cascade baryons, including differential cross section measurements for the Ξ(1320) − octet ground state, recent results for excited strangeness -1 baryons, including spin-density matrix measurements for the Λ(1520), and give a brief outlook on the GlueX potential for a spectroscopy program on excited Λ baryons.

Primary author

Volker Crede (Florida State University)

Presentation materials

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