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arxiv: 2605.23793 · v1 · pith:DXSFKC25new · submitted 2026-05-22 · ✦ hep-ph · hep-ex

Charged long-lived particles in the GMSB scenario at the Future Circular Collider (FCC-ee)

Soumyaa Vashishtha , Maximilian Emanuel Goblirsch-Kolb , Isabell Melzer-Pellmann This is my paper

Pith reviewed 2026-05-25 03:49 UTC · model grok-4.3

classification ✦ hep-ph hep-ex
keywords GMSBlong-lived stauFCC-eekinked tracksdisplaced verticessupersymmetrycharged long-lived particles
0
0 comments X

The pith

FCC-ee can detect long-lived staus in the GMSB model through kinked tracks and displaced vertices for lifetimes from 20 cm to 20 m.

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

The paper examines how the Future Circular Collider running in electron-positron mode can search for charged long-lived particles that arise in gauge-mediated supersymmetry breaking. It focuses on the case where the stau is the next-to-lightest supersymmetric particle and decays after traveling a macroscopic distance inside the detector. A reader would care because these signatures offer a concrete way to test a well-motivated supersymmetry scenario that produces particles too long-lived for most current searches to catch. The work shows that kinked tracks and displaced vertices provide the necessary experimental handles at FCC-ee. If such signals appear, they would directly constrain the parameter space of the model.

Core claim

In the gauge-mediated supersymmetry breaking scenario the stau is long-lived because of its small coupling to the gravitino; at the FCC-ee this produces observable kinked tracks when the stau decays in flight and displaced vertices when the decay occurs away from the primary interaction point, giving the experiment sensitivity to stau lifetimes between 20 cm and 20 m.

What carries the argument

Kinked tracks and displaced vertices from the in-flight decay of long-lived charged staus.

If this is right

  • The proposed collider covers a lifetime range inaccessible to most existing experiments.
  • Observation of either signature would constitute direct evidence for the GMSB scenario with a stau next-to-lightest supersymmetric particle.
  • The same signatures remain useful even if the stau mass varies within the range allowed by the model.

Where Pith is reading between the lines

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

  • Similar track-based searches could be adapted to other proposed lepton colliders if they reach comparable luminosities.
  • If no signal is seen, the null result would tighten bounds on the gravitino mass in GMSB models.
  • The method might also apply to other charged long-lived particles whose decay length falls in the same detector-scale window.

Load-bearing premise

The stau is the next-to-lightest supersymmetric particle and stays long-lived because its coupling to the gravitino is very small.

What would settle it

Absence of any kinked-track or displaced-vertex candidates in the full FCC-ee data set for the lifetime window 20 cm to 20 m would exclude the GMSB parameter region that predicts such staus.

read the original abstract

Long-lived particles have emerged as a compelling signature of physics beyond the standard model, offering unique discovery opportunities at current and future colliders. We present an analysis of charged long-lived particles leading to signatures with kinked tracks and displaced vertices. Our study is motivated by the gauge mediated supersymmetry breaking model (GMSB) within the minimal supersymmetric standard model scenario, in which the lightest supersymmetric particle is a gravitino and the next-to-lightest supersymmetric particle is the stau, the superpartner of the tau lepton. The stau is predicted to be long-lived due to the small coupling between it and the gravitino. This work presents a phenomenological study of such long-lived staus with lifetimes between 20~cm and 20~m and explores their discovery prospects at the Future Circular Collider (FCC-ee), a proposed $e^{+}e^{-}$ collider. The results highlight the sensitivity to the GMSB model.

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

1 major / 0 minor

Summary. The manuscript presents a phenomenological study of charged long-lived staus as next-to-lightest supersymmetric particles in gauge-mediated supersymmetry breaking (GMSB) models. It examines discovery prospects at the proposed FCC-ee e+e- collider for proper lifetimes in the 20 cm to 20 m range, focusing on signatures of kinked tracks and displaced vertices arising from the small stau-gravitino coupling.

Significance. If the underlying analysis is sound, the work would offer targeted sensitivity projections for long-lived particle searches in a specific SUSY scenario at a future lepton collider, complementing hadron-collider studies by exploiting the clean environment of FCC-ee.

major comments (1)
  1. [Abstract and results discussion] Abstract and results discussion: the central sensitivity claim for proper lifetimes 20 cm–20 m via kinked tracks and displaced vertices does not incorporate the mass-dependent boost factor γβ. At FCC-ee the lab-frame decay length is γβ cτ with γβ typically ≲3 and varying strongly with stau mass relative to √s/2; applying a fixed proper-lifetime window without folding in the boost distribution or specifying the collider energy stage means the quoted range does not map uniformly to observable displacements inside the tracking volume. This directly affects the load-bearing discovery-prospects statement.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and for the constructive comment on the treatment of boost factors. We address the point below and will revise the manuscript accordingly.

read point-by-point responses

  1. Referee: [Abstract and results discussion] Abstract and results discussion: the central sensitivity claim for proper lifetimes 20 cm–20 m via kinked tracks and displaced vertices does not incorporate the mass-dependent boost factor γβ. At FCC-ee the lab-frame decay length is γβ cτ with γβ typically ≲3 and varying strongly with stau mass relative to √s/2; applying a fixed proper-lifetime window without folding in the boost distribution or specifying the collider energy stage means the quoted range does not map uniformly to observable displacements inside the tracking volume. This directly affects the load-bearing discovery-prospects statement.

    Authors: We agree that the observable displacement depends on the lab-frame decay length γβ cτ and that γβ varies with stau mass and center-of-mass energy. Our quoted range refers to proper lifetime cτ in the regime where displaced signatures become relevant inside the tracking volume. To address the concern, we will revise the abstract and results discussion to specify the FCC-ee energy stages under consideration, include the typical range of γβ for the stau masses of interest, and clarify how the proper-lifetime window maps to lab-frame displacements. This will make the sensitivity claims more precise without altering the overall conclusions. revision: yes

Circularity Check

0 steps flagged

No circularity: forward-looking sensitivity projection with no fitted predictions or self-referential derivations

full rationale

The paper is a phenomenological study projecting discovery reach for long-lived staus in GMSB at FCC-ee via kinked tracks and displaced vertices. The lifetime window (20 cm–20 m) is stated as input motivated by the model's small gravitino coupling, not derived or fitted from the analysis itself. No equations, parameter fits, or predictions are presented that reduce to the inputs by construction. No self-citations are load-bearing for any central claim. The skeptic concern about mass-dependent boost is a potential modeling limitation but does not constitute circularity under the defined patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review supplies no explicit free parameters, axioms, or invented entities beyond the standard GMSB framework already present in the literature.

pith-pipeline@v0.9.0 · 5709 in / 1102 out tokens · 34240 ms · 2026-05-25T03:49:00.474215+00:00 · methodology

discussion (0)

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Reference graph

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