High-precision muon decay predictions for ALP searches

Banerjee, Pulak; Coutinho, António M.; Engel, Tim; Gurgone, A.; Signer, Adrian; Ulrich, Yannick

doi:10.21468/scipostphys.15.1.021

Cited by 6 publications

(3 citation statements)

References 109 publications

(172 reference statements)

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“…Flavor Probes of Axion Dark Matter Robert Ziegler of the SM background close to the endpoint of the Michel spectrum [31]. Present bounds on all other flavor transitions are weaker, but Belle II has the potential to improve bounds on B-meson and τ-decay by orders of magnitudes, reaching scales up to 10 9 GeV.…”

Section: Pos(discrete2022)086mentioning

confidence: 99%

Flavor Probes of Axion Dark Matter

Ziegler

2024

Proceedings of 8th Symposium on Prospects in the Physics of Discrete Symmetries — PoS(DISCRETE2022)

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Standard Model extensions with light axions are well-motivated by the observed Dark Matter abundance and the Peccei-Quinn solution to the Strong CP Problem. In general such axions can have large flavor-violating couplings to SM fermions, which naturally arise in scenarios where the Peccei-Quinn symmetry also explains the hierarchical pattern of fermion masses and mixings. I will discuss how these couplings allow for efficient axion production from the decays of SM particles, giving the opportunity to probe flavored axion Dark Matter with precision flavor experiments, astrophysics and cosmology.8th Symposium on Prospects in the Physics of Discrete Symmetries (DISCRETE 2022

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Section: Pos(discrete2022)086mentioning

confidence: 99%

Flavor Probes of Axion Dark Matter

Ziegler

2024

Proceedings of 8th Symposium on Prospects in the Physics of Discrete Symmetries — PoS(DISCRETE2022)

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“…At the endpoint of the positron energy spectrum, the emission of soft photons results in large logarithms that are resummed up to next-tonext-to-leading logarithmic (NNLL) accuracy. The details of both calculations with an evaluation of the theoretical error can be found in [5]. The result for 𝜇 + → 𝑒 + 𝜈 𝑒 ν𝜇 is shown in figure 1.…”

Section: Theoretical Predictionsmentioning

confidence: 99%

“…where A denotes the energy acceptance function and S the detector response function, which can be parametrised according to the detector simulations [1,2]. An indication of the expected sensitivity on the branching ratio of 𝜇 + → 𝑒 + 𝑋 can be estimated by applying the cut-and-count analysis described in [5] to P. Assuming a massless ALP with a 𝑉 + 𝐴 coupling to leptons, the results suggest a branching ratio sensitivity of about 2 • 10 −6 for MEG II and 10 −8 for Mu3e, which can rely on more statistics. These predictions can be compared with the upper limit of 2.5 • 10 −6 at 90% C.L.…”

Section: Expected Sensitivitymentioning

confidence: 99%

Looking for an axion in a haystack of muons

Gurgone

2023

J. Inst.

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The search for axion-like particles X in muon decays is an excellent opportunity for the MEG II and Mu3e experiments to extend their horizons beyond μ + → e + γ and μ + → e + e - e +. A suitable process for both experiments is the two-body decay μ + → e + X, whose only signature is a monochromatic peak close to the kinematic endpoint of the positron energy spectrum of the μ + → e + νeν̅μ background. The hunt for such an elusive signal in a vast amount of irreducible background requires extremely accurate theoretical predictions to be implemented in a Monte Carlo event generator. This work presents a new state-of-the-art computation of μ + → e + νeν̅μ for polarised muons, accomplished with the McMule framework. The calculation includes next-to-next-leading order QED corrections and logarithmically enhanced terms at even higher orders. The results are also used to estimate the sensitivity of both experiments on the branching ratio of μ + → e + X, in order to evaluate the impact of the theoretical error.

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New physics in multi-electron muon decays

Hostert,

Menzo,

Pospelov

et al. 2023

J. High Energ. Phys.

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We study the exotic muon decays with five charged tracks in the final state. First, we investigate the Standard Model rate for μ+ → 3e+ 2e− 2ν ($$ \mathcal{B} $$ B = 4.0 × 10−10) and find that the Mu3e experiment should have tens to hundreds of signal events per 1015μ+ decays, depending on the signal selection strategy. We then turn to a neutrinoless μ+ → 3e+ 2e− decay that may arise in new-physics models with lepton-flavor-violating effective operators involving a dark Higgs hd. Following its production in μ+ → e+hd decays, the dark Higgs can undergo a decay cascade to two e+e− pairs through two dark photons, hd→ γdγd→ 2(e+e−). We show that a μ+→ 3e+ 2e− search at the Mu3e experiment, with potential sensitivity to the branching ratio at the $$ \mathcal{O} $$ O (10−12) level or below, can explore new regions of parameter space and new physics scales as high as Λ ∼ 1015 GeV.

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High-precision muon decay predictions for ALP searches

Cited by 6 publications

References 109 publications

Flavor Probes of Axion Dark Matter

Flavor Probes of Axion Dark Matter

Looking for an axion in a haystack of muons

New physics in multi-electron muon decays

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