E. Santopinto

A three-body force model for the baryon spectrum

Abstract We present a theoretical approach to the internal baryon structure based on three-body forces among quarks. Using three-body potentials, one can both include the current two-body potential models (in an effective way) and investigate new dynamical mechanisms. The spin-independent part of the interaction is assumed to be hypercentral and treated using the hyperspherical harmonic formalism, leading to a level scheme reproducing qualitatively the observed pattern of the spectrum. We discuss some results obtained using a potential with a (mostly linear) confinement part and some inverse power terms; however the potential can be easily generalized in order to allow a systematic analysis. Adding the hyperfine interaction, which is diagonalized directly in the basis states, the spectrum can be fairly reproduced. The compatibility of the spectrum and the change form factor is briefly discussed.

STUDIES OF NUCLEON RESONANCE STRUCTURE IN EXCLUSIVE MESON ELECTROPRODUCTION

Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electropro...

ELECTROMAGNETIC TRANSITION FORM FACTORS OF NEGATIVE PARITY NUCLEON RESONANCES

We have calculated the transition form factors for electromagnetic excitation of the negative parity resonances of the nucleon using different models previously proposed, and we discuss their results and limits by comparison with experimental data.

Interacting quark-diquark model of baryons

A simple quark-diquark model of baryons with direct and exchange interactions is constructed. Spectrum and form factors are calculated and compared with experimental data. Advantages and disadvantages of the model are discussed.

Interpretation of the X(3872) as a charmonium state plus an extra component due to the coupling to the meson-meson continuum

We present a quark model calculation of the charmonium spectrum with self-energy corrections due to the coupling to the meson-meson continuum. The bare masses used in the calculation are computed within the relativized quark model by Godfrey and Isgur. The strong decay widths of

Heavy quarkonium hybrids from Coulomb gauge QCD

3S

A three-body force model for the electromagnetic excitation of the nucleon

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Electroproduction of nucleon resonances

2P

Quark structure of the

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X(3872)

1D