Abstract
We study soft and collinear gluon emission in squark decays to quark--neutralino pair, at next-to-next-to-leading logarithmic (NNLL) accuracy in the end-point region, using Soft Collinear Effective Theory (SCET), and at next-to-leading (NLO) fixed order in the rest of the phase space. As a phenomenological case study we discuss the impact of radiative corrections on the simultaneous measurements of squark and neutralino masses at a linear $e^{+}e^{-}$ collider based on $\sqrt{s} = 3$ TeV Compact Linear Collider (CLIC). Since the majority of mass measurement techniques are based on edges in kinematic distributions, and these change appreciably when there is additional QCD radiation in the final state, the knowledge of higher-order QCD effects is required for precise mass determinations.
Highlights
The discovery of dark matter (DM) in a collider experiment crucially depends on the ability to measure precisely its properties—its mass and couplings to visible matter
II, we introduce the necessary ingredients of the effective field theory (EFT) approach to the problem, that includes softcollinear effective theory (SCET) and heavy scalar effective theory (HSET)
Since the decay topology of a squark can be significantly altered by higher-order corrections, it is necessary to scrutinize these effects for the precise measurements of a squark and neutralino masses, which is an important part of the Compact measurements of squark Linear Collider (CLIC) physics program
Summary
The discovery of dark matter (DM) in a collider experiment crucially depends on the ability to measure precisely its properties—its mass and couplings to visible matter. The collinear and soft singularities of QCD contributions in the endpoint regions lead to large logarithms, L ∼ lnð1 − zÞ, in the calculation of the differential decay width, dΓ=dz. Away from the endpoint region, where 1 − z ∼ Oð1Þ, the differential rate is dominated by hard gluon emissions from squark and quark lines, giving the event rate that is OðαsÞ. This is of the same order as the NNLL corrections in the endpoint region and needs to be kept in our expressions. Appendix A contains technical details on Δ-distribution which has been used to regularize infrared (IR) divergences in the fixed NLO calculation
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