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

2. 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, (2008).
iii) P. González, E. Oset and J. Vijande
Phys. Rev. C 79, (2009).

3. 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

4. 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.

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

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

8. 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

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

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

12. 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.

13. 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:

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

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

17. Hybrid Model N R B’ R B’ m’ N p m’ p

18. 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.

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

20. 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.

23. 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.

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

25. Widths correction

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

27. 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) :

28. 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) .

29. 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.

30. THE END