Dark photons from charm mesons at LHCb

By Philip Ilten, Jesse Thaler, Mike Williams, W. Xue. 2015

136 citations recorded by the source corpus.

We propose a search for dark photons $A^{\prime}$ at the LHCb experiment using the charm meson decay $D^*(2007)^0 \!\to D^0 A^{\prime}$. At nominal luminosity, $D^{*0} \!\to D^0 \gamma$ decays will be produced at about 700kHz 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 $A^{\prime}\!\to e^+e^-$. 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 $A^{\prime}$ decay vertex is significantly displaced from the proton-proton primary vertex. The resonant strategy takes advantage of the large event rate for $D^{*0} \!\to D^0 A^{\prime}$ and the excellent invariant mass resolution of LHCb, yielding a background-limited search that nevertheless covers a significant portion of the $A^{\prime}$ parameter space. Both search strategies rely on the planned upgrade to a triggerless-readout system at LHCb in Run 3, which will permit identification of low-momentum electron-positron pairs online during data taking. For dark photon masses below about 100MeV, LHCb can explore nearly all of the dark photon parameter space between existing prompt-$A^{\prime}$ and beam-dump limits.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b2a916a5acdc026f7af9708978a86a7ce93d8034

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Citations in the corpus

Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era (2018, methodology): “These searches are based on two strategies: prompt and displaced resonance searches using D∗0 → D0e+e− decays [447] (green bands); and inclusive dimuon production [448] (blue bands).”
Expression of interest for the CODEX-b detector (2019, background): “However, the LHCb VELO and various forward detectors are already expected to greatly improve the reach for this scenario [13, 30–36].”
Particle physics models for the 17 MeV anomaly in beryllium nuclear decays (2016, unknown): “proposed [132] using the charmmeson decayD ð2007Þ0 → D0A0 with subsequent A0 → eþe−.”
Physics beyond colliders at CERN: beyond the Standard Model working group report (2019, methodology): “- LHCb @ CERN: LHCb will search for dark photon in visible final states both using the inclusive di-muon production [200] and the D∗0 → D0e+e− decays [201].”
Dark matter, millicharges, axion and scalar particles, gauge bosons, and other new physics with LDMX (2018, background): “Projected sensitivities of HPS (orange) [1], an upgraded version of SeaQuest [103] (purple), Belle II (green, 50 ab−1 integrated luminosity) [1] and LHCb (blue) [74, 75] are shown as thin dashed lines (see text for details).”
ForwArd Search ExpeRiment at the LHC (2017, background): “10 we also show the expected reach of other proposed searches for dark photons with small , namely LHCb [78, 79], HPS [80], SeaQuest [60], and SHiP [65].”
The Dark Photon (2020, methodology): “- LHCb upgrade (phase I and phase II) at the LHC: LHCb phase I will search for dark photon in visible final states both using the inclusive di-muon production (Ilten et al., 2016) and the D∗0 → D0e+e− decays (Ilten et al., 2015).”
Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider (2019, methodology): “The second proposed signature [382] exploits a tag of the radiative decay of the D 0 * using its”
Beyond the Standard Model Physics at the HL-LHC and HE-LHC (2018, background): “1, the sensitivity calculated using D⇤0 ! Dee decays [301] is based on the normalisation to this channel, which at the same time is the main background for the prompt search.”
FASER’s physics reach for long-lived particles (2018, methodology): “Besides recasting the dark photon search sensitivity at Belle-II [14], LHCb [15, 16], SeaQuest [59] and SHiP [20], they include additionally search strategies utilizing the A′ → νν decay channel at Belle-II and NA64 [18].”
Serendipity in dark photon searches (2018, methodology): “ future searches largely exploit the same production mechanisms, though some plan on using positron beams incident on xed targets for annihilation [51,63,64] or additional meson decays such as D !D0A0[57]. Dark photons have been searched for using the following techniques: by performing bump hunts i”