Z c decay width in QCD sum rules University of São Paulo F.S. Navarra Peñiscola 27/05/2013 Dias, Navarra, Nielsen, Zanetti, arXiv: New states in the charmonium spectrum Z c decay width

Before 2003: Cornell potential: Introduction “Good” quarkonium spectrum States with “wrong” masses After 2003: Schrödinger equation:

Isospin violation: Charged states: (2003) (2007)

Ten years of “bad behavior” * * (2013) BES-III BELLE CLEO c *

What is the structure of the new states ? Tetraquark Meson molecule Hybrid cc c c Hadro-charmonium New questions

Maiani (2005) X(3872) must have a charged partner Maiani (2007) Z + (4430) is its first radial excitation ! What is the relation between them ?

Maiani,Polosa,Riquer, arXiv: Navarra,Nielsen,Richard, arXiv:

Z c decay width X (3872) < 2.3 Z c (3900) ~ 50

Two body decay Phase Space

Amplitude A comes from the Lagrangian How do we know the coupling constant ? Example:

QCD sum rules hadrons quarks Coupling constants in QCD sum rules

The OPE side Z c = diquark – antidiquark …

Problem: it is very difficult to separate a diquark-antidiquark from a meson-meson current ! Fierz transformation mesons diquarks

Tetraquark has color entanglement. How to enforce it ? Require color exchange during the decay ! Color-connected diagrams

The phenomenological side Insert complete sets of states into Define ?

Choose the structure: Input numbers: Coupling constant:

Results Total width Maiani (2013)

Summary Z c is the charged partner of X (3872) Tetraquark approach reproduces the mass and the decay width

2003: X(3872) 2013: Z + (3900) Ten years of “bad behavior”

How to group the new states ? Gell-Mann fifties, sixties… 150

Problem: it is very difficult to separate a diquark-antidiquark from a meson-meson current ! Fierz transformation mesons diquarks

I knew ! I just know !