First search for sidereal and annual modulation of Z-pole asymmetries with the recovered SLD data set
Abstract
We report what is, to our knowledge, the first time-resolved analysis of electroweak asymmetries at the Z pole, using the public release of the recovered SLD collision data: 6.6×105 polarized e+e-→ Z events from the 1996-1998 SLC runs, with 385583 selected hadronic Z decays spanning 782 sidereal cycles. The left-right asymmetry ALR, reconstructed with the published SLD selection and per-event signed Compton polarization, shows no sidereal, solar-diurnal, or annual modulation; a simultaneous unbinned likelihood fit bounds the sidereal first-harmonic amplitude at 0.0086 (95% C.L., statistical). The analysis, frozen on the initial partial release, applied unchanged to the 229833 events of the later-released 1998 run confirms the null (amplitude 0.0018, p=0.90). Using the as-built SLC beam azimuth from the release's documentation corpus, we bound the asymmetry's anisotropy tensor in the Sun-centered frame: ρ1≤0.060, ρ2≤0.18, and, for vector backgrounds, ρ0≤0.092 (95% C.L.). A leading-order matching maps these onto minimal Standard-Model-Extension coefficients as 10−2-level sensitivities to the two-time-index block of the electroweak gauge-sector coefficient kW (components with no existing laboratory constraint) and to the Higgs-sector coefficient kϕϕ; the insertions split the Z pole by polarization, so for the tensor families assessed the resonance saturates the sidereal amplitude near 10−2 and the Born-model bounds exclude finite coefficient bands rather than set an upper limit. We also derive a previously unpublished Z-pole birefringence channel in the helicity-odd azimuthal modulation of the thrust axis, with response enhanced by about 2MZ/ΓZ; a Born-level pilot is null. First sidereal analyses of hadronization and leptonic asymmetries bound instrumental drifts at the 10−4-10−3 fractional level.
Related
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BibTeX
@misc{chung2026first,
title = {{First search for sidereal and annual modulation of $Z$-pole asymmetries with the recovered SLD data set}},
author = {Wonyong Chung},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40282},
eprint = {2610.40282},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40282},
}
RIS
TY - UNPB
TI - First search for sidereal and annual modulation of Z-pole asymmetries with the recovered SLD data set
AU - Wonyong Chung
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40282
UR - https://arxiv.org/abs/2610.40282
AB - We report what is, to our knowledge, the first time-resolved analysis of electroweak asymmetries at the Z pole, using the public release of the recovered SLD collision data: 6.6×10^5 polarized e^+e^-→ Z events from the 1996-1998 SLC runs, with 385583 selected hadronic Z decays spanning 782 sidereal cycles. The left-right asymmetry A_LR, reconstructed with the published SLD selection and per-event signed Compton polarization, shows no sidereal, solar-diurnal, or annual modulation; a simultaneous unbinned likelihood fit bounds the sidereal first-harmonic amplitude at 0.0086 (95% C.L., statistical). The analysis, frozen on the initial partial release, applied unchanged to the 229833 events of the later-released 1998 run confirms the null (amplitude 0.0018, p=0.90). Using the as-built SLC beam azimuth from the release's documentation corpus, we bound the asymmetry's anisotropy tensor in the Sun-centered frame: ρ_1≤0.060, ρ_2≤0.18, and, for vector backgrounds, ρ_0≤0.092 (95% C.L.). A leading-order matching maps these onto minimal Standard-Model-Extension coefficients as 10^−2-level sensitivities to the two-time-index block of the electroweak gauge-sector coefficient k_W (components with no existing laboratory constraint) and to the Higgs-sector coefficient k_ϕϕ; the insertions split the Z pole by polarization, so for the tensor families assessed the resonance saturates the sidereal amplitude near 10^−2 and the Born-model bounds exclude finite coefficient bands rather than set an upper limit. We also derive a previously unpublished Z-pole birefringence channel in the helicity-odd azimuthal modulation of the thrust axis, with response enhanced by about 2M_Z/Γ_Z; a Born-level pilot is null. First sidereal analyses of hadronization and leptonic asymmetries bound instrumental drifts at the 10^−4-10^−3 fractional level.
ER -