Dark photons from charm mesons at LHCb
Name
PhysRevD.92.115017.pdf
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1.05 MB
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Adobe PDF
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Author(s)
Thaler, Jesse
Xue, Wei
Williams, Michael
Ilten, Philip J
Date Issued
December 2015
Journal
Physical Review D
Publisher
American Physical Society
Citation
Ilten, Philip, Jesse Thaler, Mike Williams, and Wei Xue. “Dark Photons from Charm Mesons at LHCb.” Phys. Rev. D 92, no. 11 (December 21, 2015). © 2015 American Physical Society
Version
Final published version
Abstract
We propose a search for dark photons A[superscript ′] at the LHCb experiment using the charm meson decay D[superscript *](2007)[superscript 0] → D[superscript 0]A[superscript ′]. At nominal luminosity, D[superscript *0] → D[superscript 0]γ decays will be produced at about 700 kHz within the LHCb acceptance, yielding over 5 trillion such decays during Run 3 of the LHC. Replacing the photon with a kinetically mixed dark photon, LHCb is then sensitive to dark photons that decay as A[superscript ′] → e[superscript +]e[superscript -]. We pursue two search strategies in this paper. The displaced strategy takes advantage of the large Lorentz boost of the dark photon and the excellent vertex resolution of LHCb, yielding a nearly background-free search when the A[superscript ′] decay vertex is significantly displaced from the proton-proton primary vertex. The resonant strategy takes advantage of the large event rate for D[superscript *0] → D[superscript 0]A[superscript ′] and the excellent invariant-mass resolution of LHCb, yielding a background-limited search that nevertheless covers a significant portion of the A[superscript ′] parameter space. Both search strategies rely on the planned upgrade to a triggerless-readout system at LHCb in Run 3, which will permit the identification of low-momentum electron-positron pairs online during data taking. For dark photon masses below about 100 MeV, LHCb can explore nearly all of the dark photon parameter space between existing prompt-A[superscript ′] and beam-dump limits.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.92.115017
