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Probing the Higgs Portal at the Fermilab Short-Baseline Neutrino - - PowerPoint PPT Presentation
Probing the Higgs Portal at the Fermilab Short-Baseline Neutrino - - PowerPoint PPT Presentation
Probing the Higgs Portal at the Fermilab Short-Baseline Neutrino Experiments Ahmed Ismail University of Pittsburgh University of Utah Searching for new physics August 5, 2019 with Brian Batell and Josh Berger Summary Neutrino experiments
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Light hidden sector portals
- light dark matter
- muon g – 2
- neutrino masses
- ...
dark Higgs dark photon sterile neutrino
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Current limits on the Higgs portal
Scalar couples to SM through mixing with Higgs
Physics Beyond Colliders BSM report
Rare decays of B, K mesons
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Dark sectors at the Intensity Frontier
meson facilities long-lived particle searches beam dumps
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Neutrino beams are proton dumps
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Short Baseline Neutrino program
Detector Mass (t) Distance (m) SBND 112 110 MicroBooNE 60 470 ICARUS 760 600
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Facility Proton energy Protons on target Booster 8 GeV 7 x 1020 NuMI 120 GeV 8 x 1021 CHARM SPS, CERN 400 GeV 2 x 1018
Neutrino experiments as probes of hidden sectors
p S e+ e-
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Booster: 8 GeV NuMI: 120 GeV Stopped kaons not shown
Booster NuMI
Producing scalars at beam dumps
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Advances in detector technology
Water Cerenkov Tank lined with PMTs e.g. Super-K Liquid argon ns timing resolution Fermilab SBN detectors
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Neutrino events are now background
Photons travel ~10 cm before pair conversion, so most gg events look different from ee
ArgoNeuT, 1610.04102
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Neutrino events are now background
GENIE returns objects: electrons, muons, pions, photons, protons Need kinetic energy of tens of MeV to leave enough hits in LAr + smearing Assume conservatively no discrimination between muons and pions possible
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Reducing the background
Require 2 e/g or m/p, nothing else (neutrons, nuclear remnants still allowed) Cut on pair invariant mass Reconstructed scalar is boosted cut on angle → wrt beam line, energy
Fraction of events Angle between S and beam line 100 MeV S Background Booster
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p
Off-axis production
ICARUS (and mBooNE) ~7 degrees off NuMI beam line
Absorber stops beam → kaons decaying at rest (KDAR) signal Slower scalars traveling shorter distance to ICARUS
kaon decaying in fight kaon decaying at rest p S S NuMI target NuMI absorber ICARUS
← 700 m → ← 100 m →
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NuMI
Kaons decaying at rest
Monoenergetic scalars come from direction of absorber Background is still from kaons produced in target
Angle between S and beam line 100 MeV S Background Fraction of events
p kaon decaying in fight kaon decaying at rest p S S NuMI target NuMI absorber ICARUS
← 100 m → ← 700 m →
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Results
Solid – with our estimated signal effjciencies and backgrounds Large systematics assumed: S/B = 1 Bremsstrahlung for higher masses is small
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Results
Being able to deal with collinear ee would push reach improvement as low as 10 MeV Dashed – 10 events, perfect effjciency
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Outlook
Neutrino oscillation experiments = proton beam dumps probe light hidden sectors → Fermilab Short Baseline Neutrino detectors will collect 6.6 x1020 POT from Booster by 2024, allowing new leading limits on scalar portals Off-axis production from NuMI even more powerful with more POT, including novel KDAR signal
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Backup slides
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Simulating Booster and NuMI
Based on Geant 4 g4bnb, g4numi
- proton-target
interactions
- magnetic focusing
horns
- secondary production
- other extra
interactions
K+ with / without horn
Booster NuMI
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Using timing information
Scalar travels slightly under c over 100s of m Could discriminate from n with ns timing Booster: at most 84 proton bunches per pulse Each bunch lasts 2 ns, with spacing of 19 ns 15 pulses per second
Neutrinos Scalars
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5-year reach, Physics Beyond Colliders BSM report
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