Probing pair production of long-lived scalars via an off-shell Standard-Model-like Higgs boson at the LHC
Abstract
We study the collider phenomenology of a long-lived scalar particle S that arises from Higgs mixing in a broad class of Standard-Model (SM) extensions. When the mixing angle is sufficiently small, S becomes long-lived, while its pair production via the Higgs portal can remain sizable. We focus on the production channel gg → h* → SS at the LHC, mediated by an \textit{off-shell} SM-like Higgs boson. This mechanism provides a complementary probe of S in the mass region above the kinematic threshold of the conventional on-shell decay h → SS, thereby extending the accessible parameter space to heavier scalars. The long-lived S particles can decay inside the inner detector, leading to displaced vertices (DVs) accompanied by jets. We perform a detailed Monte Carlo simulation and reinterpret an existing recast of an ATLAS search for DV-plus-jets signatures in this scenario. We also consider a modified analysis strategy based on the same search to assess potential improvements in sensitivity. We find that the current ATLAS search already excludes a significant region of the parameter space, reaching scalar masses up to mS ∼ 230~GeV for a benchmark hSS coupling λv of $246$~GeV. The modified analysis and projections to the high-luminosity LHC further extend the sensitivity to wider regions of the mass--lifetime parameter space.
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BibTeX
@misc{wang2026probing,
title = {{Probing pair production of long-lived scalars via an off-shell Standard-Model-like Higgs boson at the LHC}},
author = {Lei Wang and Xianbo Yu and Zeren Simon Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.01681},
eprint = {2606.01681},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.01681},
}
RIS
TY - UNPB
TI - Probing pair production of long-lived scalars via an off-shell Standard-Model-like Higgs boson at the LHC
AU - Lei Wang
AU - Xianbo Yu
AU - Zeren Simon Wang
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2606.01681
UR - https://arxiv.org/abs/2606.01681
AB - We study the collider phenomenology of a long-lived scalar particle S that arises from Higgs mixing in a broad class of Standard-Model (SM) extensions. When the mixing angle is sufficiently small, S becomes long-lived, while its pair production via the Higgs portal can remain sizable. We focus on the production channel gg → h^* → SS at the LHC, mediated by an \textit{off-shell} SM-like Higgs boson. This mechanism provides a complementary probe of S in the mass region above the kinematic threshold of the conventional on-shell decay h → SS, thereby extending the accessible parameter space to heavier scalars. The long-lived S particles can decay inside the inner detector, leading to displaced vertices (DVs) accompanied by jets. We perform a detailed Monte Carlo simulation and reinterpret an existing recast of an ATLAS search for DV-plus-jets signatures in this scenario. We also consider a modified analysis strategy based on the same search to assess potential improvements in sensitivity. We find that the current ATLAS search already excludes a significant region of the parameter space, reaching scalar masses up to m_S ∼ 230~GeV for a benchmark hSS coupling λv of $246$~GeV. The modified analysis and projections to the high-luminosity LHC further extend the sensitivity to wider regions of the mass--lifetime parameter space.
ER -