A theoretical preprint reports that Higgs-pair production could be substantially higher in the U(1)_X SSM, a model that extends the Standard Model, than in the benchmark used for the Standard Model itself. At a 14 TeV Large Hadron Collider, the study puts the typical total production rate at 60 to 100 femtobarns, compared with 35 to 40 femtobarns for its Standard Model benchmark.
The paper presents a theoretical calculation of the process in which two Higgs bosons are produced when two gluons collide. It examines both the overall rate and how that rate changes with the energy of the collision.
A distinctive energy pattern
The predicted signal is not spread evenly across energies. It shows a sharp peak at low energy, followed by a dip and then a high-energy tail that falls slowly. In the calculations, changing gX, λH and λC can alter the peak’s height or move its position.
That shape gives the model a more specific pattern for future high-luminosity LHC measurements to examine, rather than leaving only a single total rate to compare. The preprint does not report such a measurement.
Which parameters matter most
Across the reported scans, gX and gYX have the strongest influence on the total cross section. The paper describes λH and μ as having moderate effects, while MS and κ have weaker effects. These rankings apply to the model settings and scan ranges examined in the study.
The one-parameter scans report a rising cross section as gX moves from 0.3 to 0.6 and as gYX moves from 0.05 to 0.42. The rate also increases significantly when λH rises above 0.23. For these line scans, the other baseline choices include κ fixed at 0.1 and λC fixed at minus 0.1.
The dependence on μ is less open-ended. The discussion links a leveling-off in the rate to heavy-higgsino decoupling, meaning the influence of those contributions fades. Varying MS produces a more complicated pattern, with a main resonance around 2,500 GeV, a second peak near 3,500 GeV, then a dip and a rise at larger MS.
How the calculation was constrained
The parameter sets used in the analysis are stated to reproduce a lightest CP-even Higgs mass of 125.13 ± 0.11 GeV. The authors also state that the scans satisfy several collider-related conditions: tan βη below 1.5, up- and down-squark masses above 1,500 GeV, a Z′ mass above 5.1 TeV, and a Z′-to-gB ratio of at least 6 TeV.
The calculation includes all leading-order diagrams and uses dimensional regularization, a way of handling divergent integrals, together with modified minimal subtraction. Its next-to-leading-order QCD result is separated into leading-order, virtual-correction and real-emission pieces. The next-to-leading-order corrections are evaluated in the heavy-top limit, an approximation that treats the top quark as sufficiently heavy in the relevant calculation.
What the scan can and cannot establish
Two-parameter contour scans reinforce the same broad picture. The total rate rises steadily with λH; κ has little effect when λH is small but becomes more visible at larger λH; and the variation along gYX is stronger than the variation along κ.
The authors describe the allowed-region predictions as significant new-physics corrections and suggest Higgs-pair production as a probe for future high-luminosity LHC measurements. But the paper’s conclusions remain conditional on selected benchmark parameters and the ranges examined. It reports no uncertainty bands, statistical intervals, experimental fit, exclusion, discovery projection or direct measurement.
The document is an arXiv version 1 preprint dated 26 August 2026. Its results therefore set out a theoretical target for future tests rather than evidence that the U(1)_X SSM has been observed or that any particular parameter point has been established.
Paper data and sources
Original title: Pair production of $h$ in the $U(1)_X$SSM
Authors: Yue-Tong Liu, Shu-Min Zhao, Meng-Zi Cao et al.
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-26
DOI: Not available
Original paper · Full text