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Particle Physics Seminar
Searching for Dark Photons and the X17 Anomaly with the Upgraded LHCb Detector
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Europe/Berlin
CP-03-123 - E5a Seminarraum (TUDortmund)
CP-03-123 - E5a Seminarraum
TUDortmund
20
Description
The search for new light and weakly coupled particles provides a promising avenue to probe physics beyond the Standard Model and to explore possible connections to the dark matter sector. In this seminar, I will present the first search for dark photons below the dimuon threshold at the LHC, using radiative charm decays collected with the upgraded LHCb detector during Run 3. The search targets the decay $A' \to e^+e^-$ in processes such as $D^{*} \to D A'$, exploiting the large charm production rate and the upgraded detector capabilities to probe a region of dark photon parameter space that remains largely unexplored at LHC experiments. The accessible mass range includes the region relevant to the $m(e^+e^-)\approx17$ MeV/$c^2$ (X17) anomaly reported by the ATOMKI experiment. In particular, radiative $D_s^{+}(c\bar{s})$ decays provide sensitivity to scenarios in which the hypothetical X17 boson couples to both first- and second-generation quarks, allowing models with universal quark couplings to be tested. I will present the first results obtained with a subset of the Run 3 dataset and discuss the resulting sensitivity to prompt-like dark photon models and X17-motivated scenarios.
Finally, I will briefly discuss the development of a novel inclusive trigger selection targeting photons converting to $e^+e^-$ pairs downstream of the Vertex Locator subdetector. This trigger extends the real-time reconstruction capabilities of LHCb for converted photons and displaced topologies, providing an additional tool for analyses involving photons. Downstream converted photons offer excellent photon-energy resolution at LHCb, as they are less affected by upstream material effects and their energy and direction can be reconstructed from the electron tracks and conversion vertex rather than relying solely on calorimetric photon reconstruction. This is particularly valuable for soft photons, where calorimetric reconstruction can be challenging, and can significantly improve the invariant-mass resolution in radiative decay modes. Simulation studies indicate substantial improvements in the mass resolution for several key radiative decays of interest at LHCb, highlighting the potential of this approach for both long-lived-particle searches and precision measurements involving photons.
Finally, I will briefly discuss the development of a novel inclusive trigger selection targeting photons converting to $e^+e^-$ pairs downstream of the Vertex Locator subdetector. This trigger extends the real-time reconstruction capabilities of LHCb for converted photons and displaced topologies, providing an additional tool for analyses involving photons. Downstream converted photons offer excellent photon-energy resolution at LHCb, as they are less affected by upstream material effects and their energy and direction can be reconstructed from the electron tracks and conversion vertex rather than relying solely on calorimetric photon reconstruction. This is particularly valuable for soft photons, where calorimetric reconstruction can be challenging, and can significantly improve the invariant-mass resolution in radiative decay modes. Simulation studies indicate substantial improvements in the mass resolution for several key radiative decays of interest at LHCb, highlighting the potential of this approach for both long-lived-particle searches and precision measurements involving photons.
The meeting can be followed through zoom.
Organised by
Mick Mulder, Lukas Witola