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arxiv: 2606.19723 · v1 · pith:NHXGRRGHnew · submitted 2026-06-18 · ✦ hep-ph · astro-ph.HE· hep-ex

Charged Lepton Flavor Violation at Neutrino Telescopes

Writasree Maitra , Carlos A. Arg\"uelles , P. S. Bhupal Dev , Ivan Martinez-Soler , Manibrata Sen This is my paper

Pith reviewed 2026-06-26 17:24 UTC · model grok-4.3

classification ✦ hep-ph astro-ph.HEhep-ex
keywords charged lepton flavor violationneutrino telescopesIceCubecosmic-ray muonseffective field theorymuon to tau conversionZ prime
0
0 comments X

The pith

IceCube can search for muon-to-tau conversion using its cosmic-ray muon sample to probe charged lepton flavor violation.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper proposes using the large cosmic-ray muon dataset in IceCube to look for muon-to-tau flavor-violating interactions inside the detector. The authors model these processes with effective field theory operators and derive the resulting sensitivity to the EFT scale from existing IceCube data. They also examine a concrete axial-vector Z' model and compare the projected reach to limits from low-energy experiments and colliders. Projections for IceCube-Gen2 and HUNT indicate that next-generation telescopes could extend this reach further.

Core claim

Neutrino telescopes can perform a new search for charged lepton flavor violation by identifying muon-to-tau conversions among cosmic-ray muons traversing the detector, yielding competitive constraints on the relevant EFT operators and on the mass-coupling plane of an axial-vector Z' mediator.

What carries the argument

Muon-to-tau conversion inside the IceCube volume, distinguished from ordinary muon interactions in the cosmic-ray muon sample.

If this is right

  • Existing IceCube data already constrain the scale of CLFV EFT operators at levels comparable to some low-energy searches.
  • A specific axial-vector Z' realization yields limits in the mass-coupling plane that complement collider bounds.
  • IceCube-Gen2 and HUNT projections show substantially stronger reach for the same operators.
  • The method supplies an independent probe that does not rely on neutrino beams or fixed-target setups.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The approach could be applied to any large-volume neutrino telescope that records high-energy muons.
  • If a signal appears, it would directly constrain the flavor structure of any new physics responsible for neutrino masses.
  • Combining this channel with collider searches could isolate whether the CLFV operator is vector or axial-vector in nature.

Load-bearing premise

Backgrounds from ordinary muon interactions and detector response can be controlled sufficiently to isolate a potential muon-to-tau conversion signal at the level needed for the quoted EFT sensitivities.

What would settle it

A background-only analysis of the IceCube cosmic-ray muon dataset that finds no excess of tau-like events after all standard rejection cuts would falsify the claimed sensitivity reach.

Figures

Figures reproduced from arXiv: 2606.19723 by Carlos A. Arg\"uelles, Ivan Martinez-Soler, Manibrata Sen, P. S. Bhupal Dev, Writasree Maitra.

Figure 1
Figure 1. Figure 1: FIG. 1: A schematic view of the CLFV signal topology [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: Feynman diagrams for FIG. 2: Feynman diagrams [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: The 95% CL sensitivity on the new physics scale, Λ, obtained for various EFT operators; see text for details. [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4: Sensitivity reach on the CLFV parameter space [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5: Feynman diagrams of different lepton flavor violati FIG. S5: Feynman diagrams for various tau LFV decay channels: (a) [PITH_FULL_IMAGE:figures/full_fig_p011_5.png] view at source ↗
read the original abstract

Any observation of charged lepton flavor violation (CLFV) would be a clear signal of beyond-the-Standard-Model physics. Here, we propose a novel CLFV search using neutrino telescopes with their large cosmic-ray muon samples. Specifically, we use a recent IceCube cosmic-ray muon dataset and propose a new search for muon-to-tau conversion inside the IceCube detector. We illustrate our idea with CLFV interactions described by model-independent Effective Field Theory (EFT) operators and present the IceCube sensitivity on the relevant EFT scale. We also consider a specific realization of the EFT operator in terms of an axial-vector $Z'$ interaction and show sensitivities in the $Z'$ mass-coupling plane. We compare our sensitivities with those from low-energy CLFV searches, as well as from current and future collider experiments. We also show projections from next-generation neutrino telescopes, such as IceCube-Gen2 and HUNT, and demonstrate how neutrino telescopes can provide a powerful complementary probe of CLFV.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript proposes a novel search for charged lepton flavor violation (CLFV) via muon-to-tau conversion using the large sample of cosmic-ray muons in IceCube. It employs model-independent effective field theory (EFT) operators to derive projected sensitivities on the EFT scale, considers a specific axial-vector Z' realization, compares the reach to low-energy CLFV searches and collider experiments, and provides projections for IceCube-Gen2 and HUNT.

Significance. If the background separation can be achieved, the approach would furnish a high-energy, complementary probe of CLFV that leverages existing cosmic-ray muon statistics in neutrino telescopes. The EFT framework is standard and the comparisons to other experiments are useful; the projections for next-generation detectors illustrate the method's scalability.

major comments (2)
  1. [IceCube analysis and sensitivity section] The central sensitivity claims rest on the assumption that ordinary cosmic-ray muon energy loss, stochastic losses, and detector response can be controlled to isolate a potential muon-to-tau signal after selection cuts. No explicit background model, fake-rate estimates, efficiency curves, or data-driven validation is supplied in the IceCube analysis section, rendering the quoted EFT bounds unverifiable.
  2. [Comparison with other experiments] The comparison of IceCube sensitivities to existing and future experiments assumes a particular matching of the EFT operators between the high-energy scale and the low-energy scale; the running or matching procedure is not shown explicitly, which affects the direct numerical comparison presented.
minor comments (2)
  1. [Introduction] The specific IceCube cosmic-ray muon dataset reference should be cited explicitly when first introducing the sample.
  2. [EFT framework] Notation for the EFT operators (e.g., the precise definition of the scale Λ) should be stated once in a dedicated subsection for clarity.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the thorough review and constructive feedback on our manuscript. We address each of the major comments below and plan to revise the manuscript to incorporate the suggested improvements.

read point-by-point responses

  1. Referee: [IceCube analysis and sensitivity section] The central sensitivity claims rest on the assumption that ordinary cosmic-ray muon energy loss, stochastic losses, and detector response can be controlled to isolate a potential muon-to-tau signal after selection cuts. No explicit background model, fake-rate estimates, efficiency curves, or data-driven validation is supplied in the IceCube analysis section, rendering the quoted EFT bounds unverifiable.

    Authors: We agree with the referee that the manuscript does not provide a detailed background model or efficiency curves, as the current work focuses on a phenomenological proposal for a new search channel rather than a full experimental analysis. The sensitivities are estimated based on the known large statistics of cosmic-ray muons in IceCube and standard assumptions about the distinguishability of tau-induced signatures. In the revised manuscript, we will expand the IceCube analysis section to include a more detailed discussion of the key assumptions, potential backgrounds, and how they might be mitigated, while clearly stating that these are projected sensitivities that would require dedicated experimental validation. We will also reference relevant IceCube publications on muon propagation and energy loss. revision: yes

  2. Referee: [Comparison with other experiments] The comparison of IceCube sensitivities to existing and future experiments assumes a particular matching of the EFT operators between the high-energy scale and the low-energy scale; the running or matching procedure is not shown explicitly, which affects the direct numerical comparison presented.

    Authors: We acknowledge that the explicit running and matching procedure for the EFT operators was not detailed in the manuscript. The comparisons assume standard matching at the electroweak scale with no additional running effects beyond the usual QCD and QED running for the relevant operators. In the revision, we will add an appendix or subsection that explicitly shows the matching conditions and any relevant renormalization group evolution used to relate the high-energy IceCube scale to the low-energy scales of other experiments, ensuring the numerical comparisons are fully transparent. revision: yes

Circularity Check

0 steps flagged

No circularity: proposal applies standard EFT to external IceCube dataset without self-referential reductions.

full rationale

The paper is a forward-looking proposal for a CLFV search in IceCube cosmic-ray muons using model-independent EFT operators. Sensitivities are computed from standard EFT cross sections folded with detector response and an external public dataset; no equations define a quantity in terms of itself, rename a fitted parameter as a prediction, or reduce the central result to a self-citation chain. The derivation chain remains independent of the paper's own inputs and relies on externally verifiable assumptions about backgrounds and efficiencies.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review; no explicit free parameters, axioms, or invented entities are stated beyond the standard use of EFT operators and the assumption of an axial-vector Z' interaction.

pith-pipeline@v0.9.1-grok · 5722 in / 1059 out tokens · 30743 ms · 2026-06-26T17:24:44.011163+00:00 · methodology

discussion (0)

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