arXiv subjects

Aleksandr Pustyntsev

Publications and source records attributed to Aleksandr Pustyntsev.

5 recordsLinked to original sources

arXiv2026

Sensitivity of MAGIX@MESA to BSM effects via Bethe-Heitler pair production

We explore the sensitivity of the upcoming MAGIX experiment at the MESA facility to light Beyond the Standard Model (BSM) mediators in the few to hundred MeV mass range. Utilizing high-intensity electron beams of 55 MeV and 105 MeV on a heavy $^{181}\text{Ta}$ target, we investigate the production of scalar, pseudoscalar, vector, and axial vector mediators via the Bethe-Heitler process. By optimizing the asymmetric kinematic acceptance of the double-spectrometer setup to enhance the signal over background ratio, we demonstrate that MAGIX can probe mediator-electron couplings down to $\mathcal{O}(10^{-4})$, offering a competitive probe of the dark sector in the sub-GeV mass range.

hep-ph↗

arXiv2025

New Physics Searches via Beam Normal Spin Asymmetry in Bhabha Scattering

We examine the sensitivity of the beam normal spin asymmetry in Bhabha scattering to beyond the Standard Model (BSM) mediators, in the context of the JLab polarized positron program. A key property of this observable is that the Standard Model contribution exhibits a zero crossing at a fixed scattering angle, providing a clean, effectively background-free point for these searches. We consider scalar, vector, and axial vector mediators and present projected bounds, finding that scalar and vector scenarios allow a significant extension of the search ranges beyond existing constraints.

hep-ph↗

arXiv2025

Implications of recent $\left(g-2\right)_{\mu}$ measurements for MeV-GeV dark sector searches

Recent theoretical and experimental studies of the muon magnetic moment indicate the absence of the previously reported discrepancy, providing a vital opportunity to constrain potential BSM physics. In this work, we explore the MeV-GeV mass range, where existing exclusion limits remain relatively loose. We analyze both scalar and pseudoscalar as well as vector and axial vector mediators. We demonstrate that the new bounds are not only comparable to - but in several cases, significantly more stringent than - the constraints obtained from previous collider experiments, even when near-future projections are considered.

hep-ph↗

arXiv2024

Constraints for scalars and pseudoscalars from $\left(g-2\right)_l$ and existing $e^+e^-$ colliders

Scalars and pseudoscalars with masses in the MeV to GeV range are of interest in different extensions of the Standard Model. Such particles are often associated with dark matter, the strong CP problem and the $\left(g-2\right)_{\mu}$ anomaly. In this work we investigate limits for masses of such particles and their couplings to photons and leptons which can be derived from present and currently operating $e^+e^-$ collider experiments and recent $\left(g-2\right)_{l}$ measurements. Our work expands upon previous studies in several ways, demonstrating that the interplay of both couplings is a decisive factor in this type of analyses.

hep-ph↗

arXiv2023

Improved constraints for axion-like particles from 3-photon events at $e^+e^-$ colliders

Axions and axion-like particles (ALPs) are one of the most widely discussed extensions of the Standard Model when it comes to the strong CP problem and dark matter candidates. Current experiments are focused on the indirect searches of invisible pseudoscalars in a wide parameter range. In this paper we investigate limits on ALP mass, and its couplings to photons and leptons from 3-photon annihilation at $e^+e^-$ colliders. We provide detailed calculations and apply them to the particular kinematics of the Belle II experiment, covering the ALP mass range from few hundred MeV to around 10 GeV. Our results, which improve upon previous analyses by also including the ALP coupling to electrons, show that such future analyses will allow to significantly extend the ALP search range and impose much more stringent restrictions on their couplings.

hep-ph↗