So the LHC has verified the existence of a new type of hadron consisting of two quarks and two anti-quarks whereas QCD previously predicted that the only possible arrangements were either a three quarks ( or anti-quarks ) grouping , or a quark/anti-quark grouping.

 

What does this mean for QCD ? Does it need to be scrapped ? Does it need modifying ? Is this of no significance, just an embarassement for Murray Gell-Mann ?

Is this not just two quark/antiquark pairs? That happens exceedingly rarely, i.e. the coupling is very, very small?

Couldn't help[ being reminded of this

http://www.funny-joke-pictures.com/2013/12/science-anti-dark-dont-matter-class.html#.U1EwTvmIBPk

What I read about (without understanding anything more) is that it could be two faintly coupled mesons or four quarks with bonds of similar strength between each pair.

 

As QCD makes nearly no prediction presently, observing something new shouldn't weaken it that much, would it?

...QCD previously predicted that the only possible arrangements were either a three quarks ( or anti-quarks ) grouping , or a quark/anti-quark grouping.

There are various so called exotic hadrons that are accommodated in QCD, they don't follow the "hand waving" quark construction of baryons or mesons.