Non-decoupling two-loop corrections to (g−2)μ from fermion/sfermion loops in the MSSM

Abstract

Two-loop contributions to the muon (g − 2) from fermion/sfermion loops in the MSSM are presented, and an overview of the full MSSM prediction for (g − 2) is given with emphasis on the behaviour in scenarios which are compatible with LHC data, including scenarios with large mass splittings. Compared to all previously known two-loop contributions, the fermion/sfermion-loop contributions can yield the largest numerical results. The new contributions contain the important universal quantities ∆α and ∆ρ, and for large sfermion masses the contributions are non-decoupling and logarithmically enhanced. We find up to 15% (30%) corrections for sfermion masses in the 20 TeV (1000 TeV) range.

GM2Calc: precise MSSM prediction for $$(g-2)$$ ( g - 2 ) of the muon

“…2 Sample two-loop diagrams corresponding to SUSY one-loop diagrams with additional photon loop (left), or with fermion/sfermion-loop insertion (right). The external photon can couple to each charged particle contributions even in the presence of very heavy SUSY particles [33,70,74].…”

“…2 It can be run with SLHA input or with a GM2Calc-specific input file, and it computes a μ in the MSSM fast and precisely, taking into account the recently computed two-loop contributions. In particular, in contrast to the existing public codes, it contains the fermion/sfermion-two-loop corrections [70,71], which include the universal correction ρ and potentially large nondecoupling logarithms of heavy squark or slepton masses. GM2Calc further provides resummation of n-loop (tan β) n contributions [72,73], which allows for arbitrarily high tan β (tan β being the ratio of the vacuum expectation values of the two Higgs doublets).…”

“…It goes beyond Refs. [70][71][72][73] in that it implements the tan β-resummation also for the two-loop contributions.…”

Muon (g− 2) in the Standard Model and supersymmetric extensions

“…These terms are precisely included in the counterterm computation of Refs. [12,13]. The sum of the one-loop contributions and the two-loop contributions of these references is essentially scheme independent (up to 3-loop effects and effects from non-fermion/sfermion-loop contributions).…”

Development of the electromagnetic calorimeter waveform digitizers for the Fermilab Muon g-2 experiment

“…The latest measurement performed in 2001 by the BNL E821 experiment [1] reported a measured value of a µ = (116592089 ± 63) × 10 −11 , which represents a 3-4 standard deviation discrepancy from the current SM prediction. The difference could be a sign for physics beyond the SM such as supersymmetry [2,3] or dark photon [4]. This tantalizing result motivates the new measurement of a µ that will be performed by the E989 Collaboration at Fermilab [5].…”