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arxiv: 2606.17569 · v1 · pith:45HFSIV2new · submitted 2026-06-16 · ✦ hep-ph

Search for a Time-Dependent Z' Resonance in the Dimuon Channel

Marlon P. Brade , Jeremiah D. Juevesano , Venus Abbegaile S. Carbonel , Karen E. Bustamante , Dennis C. Arogancia , Jan Mickelle V. Maratas This is my paper

Pith reviewed 2026-06-27 00:28 UTC · model grok-4.3

classification ✦ hep-ph
keywords time-dependent resonance searchZ' bosondimuon channelCMS open dataunbinned likelihoodperiodic mass modulationU(1)B-L extension
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The pith

A two-dimensional likelihood in mass and time detects resonances whose masses vary periodically over the data-taking period.

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

The paper develops a search method that uses both the invariant mass and the time of dimuon events to look for resonances whose mass changes over time. This is motivated by a benchmark model of a Z' boson whose mass modulates periodically in a U(1)B-L extension of the Standard Model. Applying the method to CMS Run G dimuon data, the analysis sets upper limits on the gauge coupling g' as a function of Z' mass for several modulation amplitudes. The results show that the time-dependent approach can produce tighter constraints than conventional time-integrated searches when signal statistics are adequate.

Core claim

We develop a two-dimensional unbinned likelihood framework in invariant mass and time that reconstructs signals tracing nontrivial trajectories in the (m,t) plane. As a benchmark we introduce a phenomenological model in which a Z' boson from a gauged U(1)B-L extension has a periodically modulating mass, producing time-dependent resonance patterns inaccessible to standard invariant-mass analyses. Using dimuon events from CMS Open Data at 13 TeV with 7.54 fb^{-1}, we derive upper limits on g' for several choices of modulation amplitude and demonstrate sensitivity gains relative to time-integrated searches in regions with sufficient signal statistics.

What carries the argument

The two-dimensional unbinned likelihood framework in invariant mass and time, which captures signals that move along trajectories in the (m,t) plane rather than remaining stationary.

If this is right

  • Upper limits on the gauge coupling g' can be set as a function of Z' mass for different values of the modulation amplitude.
  • Signals whose resonance position changes with time become accessible, whereas they remain invisible to time-integrated searches.
  • Sensitivity gains appear specifically in kinematic regions that contain enough signal events for the time evolution to be resolved.
  • The same framework can be applied to any resonance whose properties are expected to evolve during data taking.

Where Pith is reading between the lines

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

  • The method could be extended to other final states or to searches for resonances with non-periodic time dependence.
  • If time-dependent effects are present in nature, models with constant-mass assumptions may systematically underestimate the reach of collider data.
  • Future high-luminosity datasets would increase the regions where the time-dependent approach yields measurable improvements.

Load-bearing premise

The phenomenological model in which the Z' mediator mass undergoes periodic temporal modulation is a valid description of possible new physics.

What would settle it

Applying the 2D likelihood to the same CMS dimuon dataset and finding that the resulting upper limits on g' are not tighter than those from a standard 1D mass-only analysis for the benchmark modulating signal.

Figures

Figures reproduced from arXiv: 2606.17569 by Dennis C. Arogancia, Jan Mickelle V. Maratas, Jeremiah D. Juevesano, Karen E. Bustamante, Marlon P. Brade, Venus Abbegaile S. Carbonel.

Figure 1
Figure 1. Figure 1: Invariant mass distribution of dimuon events together [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Time-dependent acceptance function constructed from [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Illustration of the background structure in the ( [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Expected cross section times branching ratio as a func [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Upper limits on the coupling g ′ as a function of the mediator mass mZ ′ for different values of the modulation param￾eter κ. The dashed curve corresponds to the time-integrated case (κ = 0), while solid curves show the time-dependent results. We presented upper limits on the coupling g ′ as a function of the mediator mass for different values of the modulation parameter κ. The results show that larger mod… view at source ↗
read the original abstract

We present a time-domain search strategy for resonances with periodically varying masses in high-energy collider data. Conventional resonance searches rely on time-integrated event samples and are therefore insensitive to signals whose properties evolve during data taking. To address this limitation, we develop a two-dimensional unbinned likelihood framework in invariant mass and time, allowing the reconstruction of signals that trace nontrivial trajectories in the $(m,t)$ plane rather than appearing as stationary resonances. As a benchmark scenario, we consider a $Z'$ boson arising from a gauged $U(1)_{B-L}$ extension of the Standard Model and introduce a phenomenological model in which the mediator mass undergoes periodic temporal modulation. The resulting signal manifests as a resonance whose position changes with time, producing distinctive patterns that are inaccessible to conventional analyses based solely on invariant-mass information. The method is implemented using dimuon events from the CMS Open Data corresponding to the Run~G data-taking period at $\sqrt{s}=13~\mathrm{TeV}$, with an integrated luminosity of $7.54~\mathrm{fb}^{-1}$. We derive upper limits on the gauge coupling $g'$ as a function of the $Z'$ mass for several choices of the modulation amplitude. The results demonstrate that incorporating temporal information can enhance sensitivity relative to standard time-integrated searches, particularly in regions with sufficient signal statistics.

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 / 1 minor

Summary. The manuscript develops a two-dimensional unbinned likelihood analysis in invariant mass and time to search for resonances whose masses vary periodically during data taking. As a benchmark it adopts a Z' from a gauged U(1)_{B-L} extension whose mass is modulated periodically, applies the method to CMS Open Data dimuon events from Run G (7.54 fb^{-1} at 13 TeV), and derives upper limits on the gauge coupling g' for several modulation amplitudes. The central claim is that the time-dependent approach yields improved sensitivity relative to conventional time-integrated searches, especially where signal statistics are adequate.

Significance. If the quantitative results support the claimed sensitivity gain, the work would provide a concrete, reproducible demonstration that temporal information can be exploited in resonance searches on public collider data. The explicit construction of the 2D likelihood and the use of open data constitute clear strengths. The significance is tempered by the fact that the benchmark relies on an ad-hoc modulation whose physical motivation is not derived from the underlying theory, limiting the generality of the result.

major comments (2)
  1. [Abstract] Abstract: the assertion that 'incorporating temporal information can enhance sensitivity' is presented without any quantitative comparison to the time-integrated case, without reported fit results, systematic uncertainties, or validation plots. This absence prevents evaluation of whether the data actually support the central claim.
  2. [Benchmark scenario] Benchmark scenario paragraph: the periodic mass modulation is introduced as a phenomenological model without derivation from the U(1)_{B-L} Lagrangian or any dynamical mechanism; the reported sensitivity gain is therefore specific to this parametrization and does not automatically extend to other time-dependent signals.
minor comments (1)
  1. Notation for the modulation amplitude and the time coordinate should be defined explicitly at first use and used consistently throughout.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed review and constructive comments. We address each major point below and indicate where revisions will be made to strengthen the manuscript.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the assertion that 'incorporating temporal information can enhance sensitivity' is presented without any quantitative comparison to the time-integrated case, without reported fit results, systematic uncertainties, or validation plots. This absence prevents evaluation of whether the data actually support the central claim.

    Authors: We agree that the abstract would benefit from greater specificity. The full manuscript presents the quantitative comparison between the 2D time-dependent likelihood and the conventional time-integrated analysis in Section 4 (including limit curves for several modulation amplitudes), together with fit validation and systematic uncertainty treatment in the appendices. In the revised version we will update the abstract to include a brief quantitative statement of the observed sensitivity improvement (e.g., the factor by which upper limits on g' are strengthened in regions of adequate signal statistics) while retaining the overall length constraint. revision: yes

  2. Referee: [Benchmark scenario] Benchmark scenario paragraph: the periodic mass modulation is introduced as a phenomenological model without derivation from the U(1)_{B-L} Lagrangian or any dynamical mechanism; the reported sensitivity gain is therefore specific to this parametrization and does not automatically extend to other time-dependent signals.

    Authors: The manuscript already characterizes the modulation explicitly as a 'phenomenological model' introduced solely for benchmarking. We accept that the quantitative sensitivity gain is therefore tied to this specific parametrization and does not automatically generalize. The 2D unbinned likelihood framework itself, however, is constructed to be model-agnostic and applicable to any resonance whose mass or width varies with time. In the revision we will add a clarifying sentence in the benchmark section underscoring both the illustrative purpose of the chosen modulation and the broader applicability of the method. revision: partial

Circularity Check

0 steps flagged

No significant circularity; analysis is self-contained

full rationale

The paper defines a 2D unbinned likelihood in (m,t) and applies it to public CMS Open Data to set limits on a benchmark phenomenological Z' model with periodic mass modulation. The claimed sensitivity gain is obtained by direct numerical comparison of the 2D method versus the time-integrated 1D method on the same dataset and signal hypothesis; no equation reduces the output limits or the gain to a fitted parameter by construction, and no load-bearing self-citation or uniqueness theorem is invoked. The derivation chain consists of standard likelihood construction followed by data-driven limit setting and is therefore independent of its inputs.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 1 invented entities

The central claim rests on the validity of a new phenomenological modulation model for the Z' mass and on the assumption that time-stamped dimuon events from CMS can be treated as an unbinned sample without unaccounted time-dependent systematics.

free parameters (1)
  • modulation amplitude
    Phenomenological parameter controlling the size of the Z' mass variation over time; several discrete choices are tested.
axioms (1)
  • domain assumption A Z' boson arises from a gauged U(1)_{B-L} extension of the Standard Model.
    Benchmark scenario chosen to illustrate the time-dependent search.
invented entities (1)
  • periodic temporal modulation of Z' mass no independent evidence
    purpose: To generate a signal trajectory in the (m,t) plane that standard searches cannot capture.
    Phenomenological construct introduced specifically for this analysis; no independent evidence provided.

pith-pipeline@v0.9.1-grok · 5797 in / 1288 out tokens · 39016 ms · 2026-06-27T00:28:46.835384+00:00 · methodology

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