Probing Boosted Light Scalars in the Type-I 2HDM
Abstract
In the Type-I two-Higgs Doublet Model (2HDM), the additional scalars may be light (≲ 100 GeV) without conflicting with experimental constraints from LHC searches or from flavour observables. So far, the studies of light scalars at the LHC have been limited to exploring non-standard decays of the Standard Model (SM) Higgs boson or via bb̅ associated production followed by leptonic decays of the light scalar. A light scalar in Type-I 2HDM can evade these search strategies due to its potentially tiny coupling to the SM Higgs boson and its suppressed coupling to quarks. In this work, we study the electroweak production of scalar pairs involving the light scalar h, the pseudoscalar A and the charged Higgs boson H±. The subsequent decays of the heavy scalars into h and an electroweak gauge boson lead to multi-h final states, in which the light scalars are typically boosted owing to the hierarchical scalar spectrum. The decay of the boosted h into bb̅ can be reconstructed within a fat-jet containing a pair of b-subjets. We find that tagging such a `boosted double-b fat-jet (Jbb)' signature in association with a SM gauge boson provides an excellent probe of the Type-I 2HDM for hierarchical scalar spectra. Using multiple light mass Mh benchmarks, we demonstrate that such analysis can explore a large region of the parameter space, with the 2σ exclusion reach for the heavy scalars extending up to ∼ 560 GeV (∼ 370 GeV) at the HL-LHC with 3000~\fbi (LHC with 300~\fbi) luminosity for light scalar masses in the range $30−−70$ GeV. Furthermore, we show that significant sensitivity and even resonance reconstruction can be achieved within a model-independent framework, highlighting the robustness of this search strategy.
Versions
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BibTeX
@misc{konar2026probing,
title = {{Probing Boosted Light Scalars in the Type-I 2HDM}},
author = {Partha Konar and Tanmoy Mondal and Chandrima Sen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.13336},
eprint = {2605.13336},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.13336},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Probing Boosted Light Scalars in the Type-I 2HDM
AU - Partha Konar
AU - Tanmoy Mondal
AU - Chandrima Sen
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2605.13336
UR - https://arxiv.org/abs/2605.13336
AB - In the Type-I two-Higgs Doublet Model (2HDM), the additional scalars may be light (≲ 100 GeV) without conflicting with experimental constraints from LHC searches or from flavour observables. So far, the studies of light scalars at the LHC have been limited to exploring non-standard decays of the Standard Model (SM) Higgs boson or via bb̅ associated production followed by leptonic decays of the light scalar. A light scalar in Type-I 2HDM can evade these search strategies due to its potentially tiny coupling to the SM Higgs boson and its suppressed coupling to quarks. In this work, we study the electroweak production of scalar pairs involving the light scalar h, the pseudoscalar A and the charged Higgs boson H^±. The subsequent decays of the heavy scalars into h and an electroweak gauge boson lead to multi-h final states, in which the light scalars are typically boosted owing to the hierarchical scalar spectrum. The decay of the boosted h into bb̅ can be reconstructed within a fat-jet containing a pair of b-subjets. We find that tagging such a `boosted double-b fat-jet (J_bb)' signature in association with a SM gauge boson provides an excellent probe of the Type-I 2HDM for hierarchical scalar spectra. Using multiple light mass M_h benchmarks, we demonstrate that such analysis can explore a large region of the parameter space, with the 2σ exclusion reach for the heavy scalars extending up to ∼ 560 GeV (∼ 370 GeV) at the HL-LHC with 3000~\fbi (LHC with 300~\fbi) luminosity for light scalar masses in the range $30−−70$ GeV. Furthermore, we show that significant sensitivity and even resonance reconstruction can be achieved within a model-independent framework, highlighting the robustness of this search strategy.
ER -