Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays ofΥ(1S)

Abstract

We search for a low-mass scalar CP-odd Higgs boson, A 0 , produced in the radiative decay of the Upsilon resonance and decaying into a τ + τ − pair: Υ (1S) → γA 0 . The production of Υ (1S) mesons is tagged by Υ (2S) → π + π − Υ (1S) transitions, using a sample of (98.3 ± 0.9) × 10 6 Υ (2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3.5 GeV ≤ m A 0 ≤ 9.2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Υ (3S) decays, setting limits on the coupling of A 0 to the b b quarks in the range 0.09 − 1.9. Our measurements improve the constraints on the parameters of the Nextto-Minimal-Supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom.

Phenomenology of a very light scalar (100 MeV < m h < 10 GeV) mixing with the SM Higgs

“…The BaBar collaboration has searched in this channel for light bosons decaying to µ + µ − , τ + τ − , hadrons or escaping invisibly [77][78][79][80]. We reproduce the limits from dimuon and ditau decays [77,78] in figure 5 in solid blue and solid orange respectively, assuming the QCD correction factor F QCD discussed therein is equal to unity. Ref.…”

Exotic decays of the 125 GeV Higgs boson

“…The strongest limits are Brðϒð1SÞ → γτ þ τ − Þ ≲ 10 −5 by BABAR [102], which constraints the Yukawa coupling to satisfy y sbb ≲ 0.4 for Brðs → τ þ τ − Þ ¼ 1 [103,104]. In the SM þ S scenario, y sbb ¼ sin θ S y hbb with y hbb ≈ 0.02 in the SM.…”

Revisiting the production of ALPs at B-factories

“…Two main scenarios are typically considered in the literature, depending on the relative strength of the ALP coupling to SM and dark sector particles: either |c aχχ | |c aSM |, or |c aχχ | |c aSM |. In the first case, for m a values in the GeV range, the ALP would typically decay in the detector, leaving the signatures γa(→ jj) [38,39], γa(→ γγ) [40][41][42] and γa(→ ) [43][44][45], with = {e, µ, τ }. This scenario is dubbed the visible ALP.…”