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Leading Bounds on Micrometer to Picometer Fifth Forces from Neutron Star Cooling.
Damiano F G Fiorillo1, Alessandro Lella2,3, Ciaran A J O'Hare4
1Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany.
Physical Review Letters
|December 5, 2025
Summary
New research uses neutron star cooling to constrain hypothetical scalar particles. These findings exclude previously unverified couplings, significantly advancing searches for new physics beyond the Standard Model.
Area of Science:
- Particle Physics
- Astrophysics
- Gravitational Physics
Background:
- The equivalence principle and inverse-square law of gravity may be violated by scalar particles at short distances.
- These hypothetical scalars couple to nucleons with masses in the eV to MeV range.
Purpose of the Study:
- To establish stringent bounds on the existence of these scalar particles.
- To investigate the potential of neutron star (NS) cooling as a method for constraining these particles.
Main Methods:
- Analyzing the observed cooling data of nearby isolated neutron stars.
- Comparing the derived limits with existing bounds, such as those from supernova (SN) 1987A.
Main Results:
- Neutron star cooling provides the most stringent limits on scalar couplings (gN ≲ 5×10^{-14}) across 6 orders of magnitude in mass (mϕ).
- Scalar emissivity significantly enhances the cooling of cold neutron stars.
- These results also constrain Higgs-portal models, setting bounds on the scalar-Higgs mixing angle (sinθ ≲ 6×10^{-11}).
Conclusions:
- Observed neutron star cooling data excludes the existence of these exotic scalar particles.
- This study establishes new, superior limits for scalar particles and Higgs-portal models, advancing beyond previous constraints.
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