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arxiv: 2606.13406 · v1 · pith:WF6XANYZnew · submitted 2026-06-11 · ✦ hep-ph

Decays of heavy scalars in the Grimus-Neufeld model

Aurimas Vitkus , Simonas Drauk\v{s}as , Thomas Gajdosik This is my paper

Pith reviewed 2026-06-27 06:25 UTC · model grok-4.3

classification ✦ hep-ph
keywords Grimus-Neufeld modelinert doublet modelscalar decaysdark matterMajorana neutrinoHiggs extensionstree-level decayspseudoscalar lifetime
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The pith

Heavy scalars in the Grimus-Neufeld model undergo tree-level two-body decays whose rates fix the pseudoscalar lifetime in the inert doublet model limit.

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

The Grimus-Neufeld model extends the Standard Model by one extra Higgs doublet plus one Majorana neutrino. For selected parameter values the model can be matched onto the inert doublet model, whose neutral scalar is a dark matter candidate. The paper therefore works out the tree-level two-body decay widths of all heavy scalars and extracts the lifetime of the pseudoscalar once the inert-doublet limit is taken. These lifetimes decide whether the scalars can survive long enough to contribute to the observed dark matter density. A reader would care because the calculation supplies a concrete test that either supports or rules out this particular route to simultaneous neutrino-mass and dark-matter explanations.

Core claim

We present the tree-level two-body decays of the heavy scalars of the GNM and compute the lifetime of the pseudoscalar in the IDM limit for parameter choices that permit direct comparison to the inert doublet model.

What carries the argument

Tree-level two-body decay amplitudes of the additional neutral and charged scalars, including channels opened by the Majorana neutrino.

If this is right

  • The computed decay rates impose upper limits on the pseudoscalar lifetime and thereby restrict its possible dark matter abundance.
  • Decay channels that involve the Majorana neutrino produce collider signatures absent from the pure inert doublet model.
  • The lifetime result supplies a direct criterion for whether the scalars can remain cosmologically stable.
  • Matching the two models isolates the quantitative effect of the neutrino sector on scalar stability.

Where Pith is reading between the lines

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

  • If the Majorana neutrino is light, extra decay modes would shorten the lifetime and further exclude a dark matter role.
  • The rates can be folded into LHC missing-energy searches to predict signals for inert-like scalars.
  • Inclusion of loop-induced or three-body decays would tighten the lifetime bound in lighter mass regions.
  • The parameter matching constrains the allowed size of the neutrino Yukawa couplings.

Load-bearing premise

Certain parameter choices allow the Grimus-Neufeld model to be directly compared to the inert doublet model so that its scalars could contribute to dark matter.

What would settle it

A collider measurement or cosmological calculation showing the pseudoscalar lifetime is too short to yield the observed dark matter relic density would rule out the contribution scenario.

Figures

Figures reproduced from arXiv: 2606.13406 by Aurimas Vitkus, Simonas Drauk\v{s}as, Thomas Gajdosik.

Figure 1
Figure 1. Figure 1: The amplitude of a neutral Higgs boson S = h0, H0, A going into: (a) to gauge bosons V, V ′ = γ, Z, W; (b) to neutral Higgses S ′ , S′′ = h0, H0, A; (c) a charged Higgs boson and a W boson; (d) to another neutral Higgs boson and a neutral gauge boson; (e) two charged fermions fj and ¯fk; (f) two Majorana neutrinos nj and nk. 2These sines and cosines are not the same as in eq. (21) and will only be used in … view at source ↗
Figure 2
Figure 2. Figure 2: The lower limit on the decay rate of the pseudoscalar [PITH_FULL_IMAGE:figures/full_fig_p012_2.png] view at source ↗
read the original abstract

We consider an extension of the Standard Model by an additional Higgs doublet and a Majorana neutrino, which we call the Grimus-Neufeld Model (GNM). For certain parameter choices the GNM can be compared to the Inert Doublet Model (IDM), which has a scalar dark matter candidate. This motivates that the scalars of the GNM could possibly contribute to dark matter. To check this, we present the tree-level two-body decays of the heavy scalars of the GNM and compute the lifetime of the pseudoscalar in the IDM limit.

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

0 major / 2 minor

Summary. The manuscript considers the Grimus-Neufeld Model (GNM), an extension of the Standard Model by an additional Higgs doublet and a Majorana neutrino. For certain parameter choices the GNM can be compared to the Inert Doublet Model (IDM). The central results are the explicit tree-level two-body decay widths of the heavy scalars in the GNM together with the lifetime of the pseudoscalar evaluated in the IDM limit of the GNM.

Significance. If the calculations are correct, the work supplies concrete, model-specific decay rates and a lifetime that can be directly compared with experimental constraints and used to assess whether GNM scalars could contribute to dark matter phenomenology via the IDM limit. The explicit presentation of tree-level widths in this context is a useful addition to the literature on extended Higgs sectors.

minor comments (2)
  1. [Abstract] Abstract: the phrase 'we present the tree-level two-body decays' would be strengthened by a brief indication of the final expressions or numerical ranges obtained rather than only describing the scope of the computation.
  2. The connection between the GNM and IDM is stated as motivation but the precise parameter mapping (e.g., which couplings are set to zero or identified) should be stated explicitly in the section that defines the IDM limit, even if the decay calculation itself does not depend on it.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive summary, significance assessment, and recommendation of minor revision for our manuscript on tree-level decays in the Grimus-Neufeld Model and the pseudoscalar lifetime in the IDM limit. No specific major comments were provided in the report.

Circularity Check

0 steps flagged

No significant circularity; direct computation of decay widths

full rationale

The paper's central claim is the explicit tree-level calculation of two-body decay widths for heavy scalars in the Grimus-Neufeld model, followed by evaluation of the pseudoscalar lifetime in the IDM limit. This is a standard model-building exercise that starts from the Lagrangian and derives widths via standard Feynman rules and phase-space integrals. No parameter is fitted to data and then relabeled as a prediction, no self-citation supplies a uniqueness theorem or ansatz that the present work depends on, and no quantity is defined in terms of itself. The IDM-limit comparison is a parameter choice, not a definitional loop. The derivation is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 2 invented entities

Abstract only; the model itself introduces the extra doublet and neutrino, but no free parameters, additional axioms, or invented entities beyond the model definition are visible.

axioms (1)
  • domain assumption Standard Model extended by one additional Higgs doublet and one Majorana neutrino
    Model definition stated in the abstract.
invented entities (2)
  • Additional Higgs doublet no independent evidence
    purpose: Extend the Standard Model
    Introduced as part of the GNM definition
  • Majorana neutrino no independent evidence
    purpose: Extend the Standard Model
    Introduced as part of the GNM definition

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