AN EXPLANATION OF THE D5/2-(1930) AS A rD BOUND STATE

i) P. González, J. Vijande, A. Valcarce and H. Garcilazo References i) P. González, J. Vijande, A. Valcarce and H. Garcilazo Eur. Phys. J. A 29, 235 (2006). ii) P. González, J. Vijande and A. Valcarce Phys. Rev. C 77, 065213 (2008). iii) P. González, E. Oset and J. Vijande Phys. Rev. C 79, 025209 (2009).

Motivation The nature of the D5/2-(1930)(***) has been a matter of controversy since its discovery in 1976 (Cutkosky et al., PRL 37, 645 (1976)). Most quark models (doing well for the baryon spectrum) overpredict its mass by more than 150 MeV. ii) There is a compelling evidence of hadron resonances that are more than states

i) Phenomenological Models. ii) Theoretical Models. INDEX i) Phenomenological Models. ii) Theoretical Models. iii) A schematic (3q + mB) model. . iv) D5/2-(1930)(***) as a rD bound state. v) Data Analyses: SNIP (Star Number Increase Prescription). vi) Summary.

Phenomenological Models CMB (CUTKOSKY) : KSU (MANLEY) : Pitt - ANL (VRANA) : Expanded version of CMB + VPI-GWU (ARNDT) :

Theoretical Models Quark Models R N p (3q) R N p (4q1q)

Constituent Two-body Quark Models Isgur-Karl model: Isgur-Karl 1978 Relativized quark model: Isgur-Capstick 1986 Goldstone boson exchange model: Glozman-Riska 1996 Instanton-induced model: Blask et al. 1990

The Isgur-Karl Model (1978) Quark-quark potential

Baryon (3q system): two relative (Jacobi) coordinates. Band Number: Parity:

D(1930) N = 3 N =1, L =1 is symmetry forbidden The D(1930) is the lowest state with N =1, L =1 is symmetry forbidden (T=3/2, S=3/2, orbitally symmetric) N = 3 Quark Pauli Blocking is responsible for high mass prediction.

S - wave Meson-Baryon Thresholds Quark Pauli Blocking suggests that components could be relevant to determine the mass of the resonance. is also present in and We look for common S-wave meson-baryon thresholds:

Meson Baryon Models R N p (m'B') B' m'

Lagrangian Meson Exchange Models Mainz, Giessen, KVI, Bonn, Juelich, Valencia,…

Hybrid Model N R B’ R B’ m’ N p m’ p

The EBAC Model Introduces bare N* states to represent the quark-core components of the nucleon resonances. The masses of the bare states are parameters that may be identified with constituent quark model predictions. Bare masses differ from experimental ones by mass shifts due to the coupling of bare states with meson-baryon scattering states.

Schematic Model Consider a system of 1 confined channel (3q) in interaction with 1 free channel (meson-baryon). Hamiltonian Matrix: with

The couple channel solutions correspond to the eigenvalues of : With a = 85 MeV all the anomalous masses can be reproduced within their experimental error bars.

D5/2-(1930)(***) as a rD bound state This approach may be also giving account, through the effective interaction, of a meson-baryon bound state.

G : Loop function for intermediate state, regularized with a cutoff.

Widths correction

correction It turns out to be negligible. The D(1930) can be a bound state

plays an essential role in the description of D(1930) For D(1930) only the phenomenological analyses including the meson-baryon threshold channel extract the resonance. CMB (CUTKOSKY) : KSU (MANLEY) : Pitt - ANL (VRANA) : Expanded version of CMB + VPI-GWU (ARNDT) :

SNIP (Star Number Increase Prescription) The inclusion of meson-baryon S-wave thresholds as inelastic channels could make anomalous resonances show up distinctively. The analysis of three pion production data could provide confirmation of the D(1930) .

Summary There is a systematic of anomalous resonances (overpredicted mass) from two-quark interaction models. All the anomalous resonances have in common the presence of meson-baryon S-wave thresholds in between the quark prediction and the tabulated average mass. For D(1930) either a shifted pole interpretation or a rD bound state is feasible. A prescription for data analyses (SNIP) is proposed.

THE END