Double-charm tetraquark

The double-charm tetraquark (T⁺
_cc, ccud) is a type of long-lived tetraquark that was discovered in 2021 in the LHCb experiment conducted at the Large Hadron Collider.^[3][4][2][5] It contains four quarks: two charm quarks, an anti-up and an anti-down quark.^[1]

Double-charm tetraquark

Classification	meson
Composition	2 charm quarks 1 up antiquark 1 down antiquark
Statistics	bosonic
Family	hadron
Mass	3868±124 MeV/c2[1]
Mean lifetime	1.35+0.31 −0.21×10−21 s[1]
Electric charge	+1
Spin	1+[1]
Isospin	0[2]

It has a theoretical computed mass of 3868±124 MeV/c².^[1] The discovery showed an exceptionally strong peak, with 20-sigma significance.^[6]

It is hypothesized that studying the behavior of the double-charm tetraquark may play a part in explaining the behavior of the strong force.^[7] Following the discovery of the T⁺
_cc, researchers now plan experiments to find its double-beauty counterpart T_bb.^[8] This tetraquark has been found to have a longer lifespan than most known exotic-matter particles.