Hunting wino and higgsino dark matter at the muon collider with disappearing tracks

Abstract

We study the capabilities of a muon collider experiment to detect disappearing tracks originating when a heavy and electrically charged long-lived particle decays via X+→ Y+Z0, where X+ and Z0 are two almost mass degenerate new states and Y+ is a charged Standard Model particle. The backgrounds induced by the in-flight decays of the muon beams (BIB) can create detector hit combinations that mimic long-lived particle signatures, making the search a daunting task. We design a simple strategy to tame the BIB, based on a detector-hit-level selection exploiting timing information and hit-to-hit correlations, followed by simple requirements on the quality of reconstructed tracks. Our strategy allows us to reduce the number of tracks from BIB to an average of 0.08 per event, hence being able to design a cut-and-count analysis that shows that it is possible to cover weak doublets and triplets with masses close to $$ \sqrt{s}/2 $$ s / 2 in the 0.1–10 ns range. In particular, this implies that a 10 TeV muon collider is able to probe thermal MSSM higgsinos and thermal MSSM winos, thus rivaling the FCC-hh in that respect, and further enlarging the physics program of the muon collider into the territory of WIMP dark matter and long-lived signatures. We also provide parton-to-reconstructed level efficiency maps, allowing an estimation of the coverage of disappearing tracks at muon colliders for arbitrary models.

Improved $${(g-2)_\mu }$$ measurements and wino/higgsino dark matter

“…Very recent analysis using vector boson fusion processes[137] or a future muon collider[138] for compressed (higgsino) spectra have not been taken into account.…”

Learning from Radiation at a Very High Energy Lepton Collider

“…In Soft-Collinear Effective Theory (SCET) the expansion is already organized in exponential form. In that case the resummation of double logarithms [45] as well as its extension to leading (LL ) 5 and next-to-leading (NLL) logarithm [49] has been studied. The study of EW parton distribution or fragmentation functions [52][53][54][55][56] is obviously connected, but not directly relevant for very high energy processes, where the main role is played by the emission of EW radiation that is both collinear and soft.…”

“…Such a Very High Energy Lepton Collider (VHEL) could greatly advance the post-LHC knowledge of fundamental physics [1] by directly searching for new heavy particles (see e.g. [3][4][5][6]), and by precise measurements of ElectroWeak (EW) scale processes exploiting the high luminosity of virtual vector bosons pairs (see e.g. [6][7][8]).…”

Precision test of the muon-Higgs coupling at a high-energy muon collider

“…Thanks to the technological development [21], a renewed idea that has recently gathered much momentum is the option of a high-energy muon collider that could reach the multi-(tens of) TeV regime with very high luminosity [22][23][24]. It has been demonstrated in the recent literature that a highenergy muon collider has great potential for new physics searches at the energy frontier from direct µ + µ − annihilation and a broad reach for new physics from the rich partonic channels [25][26][27][28][29], as well as precision measurements for SM physics [30] and beyond [31][32][33][34][35][36][37][38][39]. Of particular importance is the connection between the muon collider expectation and the tantalizing hint for new physics from the muon g − 2 measurement [40,41].…”