Muon<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>g</mml:mi><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>, rare kaon decays, and parity violation from dark bosons

Davoudiasl, Hooman; Lee, Hye-Sung; Marciano, William J.

doi:10.1103/physrevd.89.095006

Cited by 188 publications

(192 citation statements)

References 126 publications

Supporting

Mentioning

184

Contrasting

Unclassified

Order By: Relevance

“…at 90% CL, in agreement with earlier generic estimates [2,24]. This sensitivity is not competitive with the existing exclusion limits.…”

Section: Data Samplesupporting

confidence: 90%

Search for the dark photon in $\pi^0$ decays

Fantechi¹

2016

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2015)

View full text Add to dashboard Cite

A sample of 1.69 × 10 7 fully reconstructed π 0 → γ e + e − decay candidates collected by the NA48/2 experiment at CERN in 2003-2004 is analyzed to search for the dark photon ( A ) production in the π 0 → γ A decay followed by the prompt A → e + e − decay. No signal is observed, and an exclusion region in the plane of the dark photon mass m A and mixing parameter ε 2 is established. The obtained upper limits on ε 2 are more stringent than the previous limits in the mass range 9 MeV/c 2 < m A < 70 MeV/c 2 . The NA48/2 sensitivity to the dark photon production in the K ± → π ± A decay is also evaluated. Letters B 746 (2015) [178][179][180][181][182][183][184][185] IntroductionKaons are a source of tagged neutral pion decays, and high intensity kaon experiments provide opportunities for precision π 0 decay measurements. The NA48/2 experiment at the CERN SPS collected a large sample of charged kaon (K ± ) decays in flight, corresponding to about 2 × 10 11 K ± decays in the fiducial decay volume. This letter reports the search for a hypothetical dark photon (DP, denoted A ) using a large sample of tagged π 0 mesonsIn a rather general set of hidden sector models with an extra U (1) gauge symmetry [1], the interaction of the DP with the visible sector proceeds through kinetic mixing with the Standard Model (SM) hypercharge. Such scenarios with GeV-scale dark matter provide possible explanations to the observed rise in the cosmic-ray positron fraction with energy and the muon gyromag-. The DP is characterized by two a priori unknown parameters, the mass m A and the mixing parameter ε 2 . Its possible production in the π 0 decay and its subsequent decay proceed via the chain π 0 → γ A , A → e + e − . The expected branching fraction of the above π 0 decay is [3] B(π( 1) which is kinematically suppressed as m A approaches m π 0 . In the DP mass range 2m e < m A < m π 0 accessible in pion decays, the only allowed tree-level decay into SM fermions is A → e + e − , while the loop-induced SM decays ( A → 3γ , A → νν) are highly suppressed. Therefore, for a DP decaying only into SM particles, This analysis is performed assuming that the DP decays at the production point (prompt decay), which is valid for sufficiently large values of m A and ε 2 , as quantified in Section 5. In this case, the DP production and decay signature is identical to that of the Dalitz decay π 0 D → e + e − γ , which therefore represents an irreducible but well controlled background and determines the sensitivity. B(A →eThe NA48/2 experiment provides pure π 0 D decay samples through the reconstruction of K ± → π ± π 0 andis considered as a background in the K μ3sample. The K ± → π 0 e ± ν decay is not considered for this analysis because of the ambiguity due to three e ± particles in the final state. Beam, detector and data sampleThe NA48/2 experiment used simultaneous K + and K − beams produced by 400 GeV/c primary CERN SPS protons impinging on a beryllium target. Charged particles with momenta of (60 ± 3) GeV/c were selected by an achromatic syste...

show abstract

“…at 90% CL, in agreement with earlier generic estimates [2,24]. This sensitivity is not competitive with the existing exclusion limits.…”

Section: Data Samplesupporting

confidence: 90%

Search for the dark photon in $\pi^0$ decays

Fantechi¹

2016

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2015)

View full text Add to dashboard Cite

show abstract

“…The dark photon model can be generalized by assuming that γ d and the SM Z boson couple to a dark second Higgs doublet that induces γ d − Z mass-mixing, in which case the resulting light Z d (a linear γ d − Z combination) acts much like a light "dark Z" [8], with interesting additional implications, such as changes in the low q 2 running of the weak mixing angle [12,13], and rare decays of K, B and H particles into final states with Z d 's [8].…”

Section: Introductionmentioning

confidence: 99%

Implications of a light “dark Higgs” solution to thegμ−2discrepancy

et al. 2016

Self Cite

View full text Add to dashboard Cite

A light scalar φ with mass < ∼ 1 GeV and muonic coupling O(10 −3 ) would explain the 3.5 σ discrepancy between the Standard Model (SM) muon g − 2 prediction and experiment. Such a scalar can be associated with a light remnant of the Higgs mechanism in the"dark" sector. We suggest φ → l + l − bump hunting in µ → eννφ, µ − p → νµnφ (muon capture), and K ± → µ ± νφ decays as direct probes of this scenario. In a general setup, a potentially observable muon electric dipole moment < ∼ 10 −23 e · cm and lepton flavor violating decays τ → µ(e)φ or µ → eφ can also arise. Depending on parameters, a deviation in BR(H → µ + µ − ) from SM expectations, due to Higgs coupling misalignment, can result. We illustrate how the requisite interactions can be mediated by weak scale vector-like leptons that typically lie within the reach of future LHC measurements.

show abstract

“…In searches for new physics, the precision will allow us to exclude 4-fermion contact interactions with mass scales up to 49 TeV, corresponding to the reach at the LHC with an integrated luminosity of 300 fb −1 . The planned experiment will be able to exclude models which change the running of the weak mixing angle, induced for example by new light gauge bosons [18], thus complementing other searches for so-called dark photons or Z-bosons.…”

Section: Resultsmentioning

confidence: 99%