squarks

Squarks are hypothetical particles predicted by supersymmetric extensions of the Standard Model. They are the scalar superpartners of quarks, carrying the same gauge quantum numbers as their quark counterparts but with spin 0. As color triplets with baryon number 1/3, squarks participate in strong interactions in addition to electroweak interactions with neutralinos and charginos.

There are six flavors of squarks, corresponding to the six quarks: up, down, charm, strange, top, and bottom. For each flavor there are left-handed and right-handed squark states, denoted q̃L and q̃R. The mass eigenstates are mixtures of these states, usually labeled q̃1 and q̃2, with q̃1 typically lighter. Mixing is especially notable for the top and bottom squarks (stops and sbottoms) due to large Yukawa couplings.

In high-energy collisions, squarks would be produced predominantly in pairs through strong interactions. Once produced, they typically decay into a quark plus a neutralino or a chargino, with subsequent decays down to the lightest supersymmetric particle (LSP). If R-parity is conserved, the LSP is stable and escapes detection, producing missing transverse energy in events that also contain jets and sometimes leptons.

Experimental status: squarks have not been observed. Searches at the Large Hadron Collider have set lower bounds on squark masses, generally in the hundreds of GeV to the TeV range, depending on the assumed SUSY spectrum and decay channels. Scenarios with compressed mass spectra can evade some limits, but no conclusive discovery has been made.