Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures ...unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon (A^{'}) is light enough to generate an attractive force between dark fermions. We report herein a search for a J^{PC}=1^{--} darkonium state, the ϒ_{D}, produced in the reaction e^{+}e^{-}→γϒ_{D}, ϒ_{D}→A^{'}A^{'}A^{'}, where the dark photons subsequently decay into pairs of leptons or pions, using 514 fb^{-1} of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the γ-A^{'} kinetic mixing as a function of the dark sector coupling constant for 0.001<m_{A^{'}}<3.16 GeV and 0.05<m_{ϒ_{D}}<9.5 GeV.
Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the ...first search for a stable, doubly strange six-quark state in ϒ→SΛover ¯Λover ¯ decays based on a sample of 90×10^{6}ϒ(2S) and 110×10^{6}ϒ(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined ϒ(2S,3S)→SΛover ¯Λover ¯ branching fraction in the range (1.2-1.4)×10^{-7} are derived for m_{S}<2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.
We report on the first search for electron-muon lepton flavor violation (LFV) in the decay of a b quark and b antiquark bound state. We look for the LFV decay ϒ(3S)→e^{±}μ^{∓} in a sample of ...118 million ϒ(3S) mesons from 27 fb^{-1} of data collected with the BABAR detector at the SLAC PEP-II e^{+}e^{-} collider operating with a 10.36 GeV center-of-mass energy. No evidence for a signal is found, and we set a limit on the branching fraction Bϒ(3S)→e^{±}μ^{∓}<3.6×10^{-7} at 90% C. L. This result can be interpreted as a limit Λ_{NP}/g_{NP}^{2}>80 TeV on the energy scale Λ_{NP} divided by the coupling-squared g_{NP}^{2} of relevant new physics (NP).
We measure the mass difference Δm0 between the D*(2010)+ and the D0 and the natural linewidth Γ of the transition D*(2010)+ → D0π+. The data were recorded with the BABAR detector at center-of-mass ...energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477 fb(-1). The D0 is reconstructed in the decay modes D0 → K- π+ and D0 → K- π+ π- π+. For the decay mode D0 → K- π+ we obtain Γ = (83.4±1.7±1.5) keV and Δm0 = (145425.6±0.6±1.7) keV, corrected where the quoted errors are statistical and systematic, respectively. For the D0 → K- π+ π- π+ mode we obtain Γ = (83.2±1.5±2.6) keV and Δm0 = (145426.6±0.5±1.9) keV. corrected The combined measurements yield Γ = (83.3±1.2±1.4) keV and Δm0 = (145425.9±0.4±1.7) keV; the width is a factor of approximately 12 times more precise than the previous value, while the mass difference is a factor of approximately 6 times more precise.
The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly ...decaying b-hadrons,
. The average value of
is measured to be 0.699±0.011. The resulting
distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of b-hadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data:
with a correlation factor
ρ
=92.2%.
Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of
is found to be 0.7092±0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained:
with a correlation factor
ρ
=92.6%.
Abstract X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder. The disease is the consequence of mutations in the ABCD1 gene that encodes the peroxisomal membrane protein ...ALDP which is involved in the transmembrane transport of very long-chain fatty acids. We describe a family with six members carrying a novel heterozygous mutation IVS4+2T>A (c.1393+2T>A) of the ABCD1 gene, highlighting the wide range of phenotypic manifestations of ALD and the importance of genetic screening before any pregnancy in asymptomatic women whose carrier status is unknown.
We present results of a search for CP violation in B0- B0 mixing with the BABAR detector. We select a sample of B0→D*- Xℓ+ ν decays with a partial reconstruction method and use kaon tagging to assess ...the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP≡N(B0B0)-N(B0B0)/N(B0B0)+N(B0B0)=(0.06±0.17(-0.32)(+0.38))%, corresponding to ΔCP=1-|q/p|=(0.29±0.84(-1.61)(+1.88))×10(-3).
We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}→D^{+}π^{0} with D^{+}→K^{-}π^{+}π^{+}. The data were recorded with the BABAR ...detector at center-of-mass energies at and near the ϒ(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8stat±12.9syst) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8stat±12.9syst) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.
PDF
