Spin measurements in cascade decays at the LHC

We systematically study the possibility of determining the spin of newparticles after their discovery at the LHC. We concentrate on angularcorrelations in cascade decays. Motivated by constraints of electroweakprecision tests and the potential of providing a Cold Dark Matter candidate, wefocus on scenarios of new physics in which some discrete symmetry guaranteesthe existence of stable neutral particles which escape the detector. Morespecifically, we compare supersymmetry with another generic scenario in whichnew physics particles have the same spin as their Standard Model partners. Asurvey of possibilities of observing spin correlations in a broad range ofdecay channels is carried out, with interesting ones identified. Rather thanconfining ourselves to one "collider friendly" benchmark point (such as SPS1a),we describe the parameter region in which any particular decay channel iseffective. We conduct a more detailed study of chargino's spin determination inthe decay channel $\tilde{q}\to q + \tilde{C}^\pm \to q + W^\pm + LSP$. A scanover the chargino and neutralino masses is performed. We find that as long asthe spectrum is not too degenerate the prospects for spin determination in thischannel are rather good.Comment: 36 pages, references added, 1 figure modifie