Frank Simon

We present the operation with moderate radiation shield in a surface laboratory of BULky and Low-threshold Kinetic Inductance Detector) (BULLKID), a cryogenic detector for searches of light dark matter or coherent elastic neutrino-nucleus scattering. The detector consists of an array of 60 cubic silicon particle absorbers of 0.34 g each, sensed by cryogenic kinetic inductance detectors. The analysis presented focuses on data from 15 elements of the array, with two central units used to evaluate the background and with their surrounding elements used as veto. The low energy spectrum resulting from an exposure of 290 hours to ambient backgrounds, acquired with the use of external and internal radiation shields, is compatible with the simulations at the level of ( 6.8 ± 0.4 stat . ± 0.1 syst . ) × 10 4 counts / keV kg days from 2 keV down to an energy of 600 eV. The region between 225 eV and 600 eV shows a rise in background in disagreement with the simulations, while not sharing some of the key traits of the low energy excess observed in other cryogenic experiments. The high energy spectrum shape is in overall agreement with the simulations and displays the typical particle-induced x-ray emission of the surrounding lead.

We study the processes e + e − → ϒ J ( 1 D ) η and e + e − → ϒ J ( 1 D ) π + π − at center-of-mass energies s = ( 10.73 − 11.02 ) GeV using a 142.5 fb − 1 data sample, including 122 fb − 1 near the ϒ ( 10860 ) peak ( s = 10.866 GeV ), collected with the Belle detector at the KEKB asymmetric-energy e + e − collider. From the peak sample, the products of Born cross section times branching fraction are obtained for σ Born ( e + e − → ϒ J ( 1 D ) η ) or σ Born ( e + e − → ϒ J ( 1 D ) π + π − ) and B ( ϒ J ( 1 D ) → χ b 1 γ ) or B ( ϒ J ( 1 D ) → χ b 2 γ ) for each ϒ J ( 1 D ) state. The corresponding branching fractions for ϒ ( 10860 ) decays are also obtained. The significances of the ϒ 1 ( 1 D ) , ϒ 2 ( 1 D ) , and ϒ 3 ( 1 D ) signals are 4.8 σ , > 10 σ , and 3.0 σ , respectively, including systematic uncertainties. The mass for ϒ 2 ( 1 D ) is measured to be ( 10167.0 ± 1.0 ± 0.2 ) MeV / c 2 , where the first and second uncertainties are statistical and systematic. The mass splittings Δ m 12 = m ( ϒ 2 ( 1 D ) ) − m ( ϒ 1 ( 1 D ) ) and Δ m 23 = m ( ϒ 3 ( 1 D ) ) − m ( ϒ 2 ( 1 D ) ) are ( 11.8 ± 1.5 ± 0.4 ) MeV / c 2 and ( 7.6 ± 2.4 ± 0.6 ) MeV / c 2 , respectively. We determine the energy dependence of the cross sections for e + e − → ϒ J ( 1 D ) η and e + e − → ϒ J ( 1 D ) π + π − for the ϒ 1 ( 1 D ) , ϒ 2 ( 1 D ) , and ϒ 3 ( 1 D ) states, combined.

We report the first observation of the decays B + → Σ c ( 2455 ) + + Ξ ¯ c ′ − and B 0 → Σ c ( 2455 ) 0 Ξ ¯ c ′ 0 , with significances of 6.4 σ and 5.3 σ , respectively, including systematic uncertainties. This analysis is based on data samples containing 771.6 × 10 6 ϒ ( 4 S ) decays collected with the Belle detector at the KEKB collider and 520.6 × 10 6 ϒ ( 4 S ) decays collected with the Belle II detector at the SuperKEKB collider. The branching fractions are measured to be B ( B + → Σ c ( 2455 ) + + Ξ ¯ c ′ − ) = ( 1.69 ± 0.31 ± 0.1 2 − 0.56 + 1.39 ) × 10 − 3 and B ( B 0 → Σ c ( 2455 ) 0 Ξ ¯ c ′ 0 ) = ( 1.28 ± 0.32 ± 0.1 0 − 0.22 + 0.26 ) × 10 − 3 , where the first and second uncertainties are statistical and systematic, respectively, and the third arises from the uncertainties in the absolute branching fractions of Ξ ¯ c − and Ξ ¯ c 0 decays. This result represents the first observation of B -meson decays into a pair of charmed baryon-antibaryon states belonging to the same S U ( 3 ) flavor sextet.

We report the first searches for charged-lepton-flavor violation in decays of χ b J ( 1 P ) ( J = 0 , 1, and 2) to a pair of charged leptons using 158 million ϒ ( 2 S ) decays collected with the Belle detector in e + e − collisions at the KEKB collider. No significant signal is observed, and we set upper limits on the branching fractions for χ b J ( 1 P ) decays to e ± μ ∓ at the level of 10 − 6 and to e ± τ ∓ or μ ± τ ∓ at the level of 10 − 5 . Limits on χ b 0 ( 1 P ) decays are translated into bounds on the corresponding Wilson coefficients of scalar operators that mediate charged-lepton-flavor violation.

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,200 new measurements from 903 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Most of the 118 reviews are updated, including many that are heavily revised. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 96 review articles. Volume 2 consists of the Particle Listings and contains also 22 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group ( pdg.lbl.gov ) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app. The PDG API (Application Programming Interface) provides access to the data published in the Review in machine-readable format.

Using a data sample of 427.9 fb − 1 collected by the Belle II detector at or near the ϒ ( 4 S ) and ϒ ( 10753 ) resonances, the cross sections for e + e − → h + h − J / ψ ( h = π / K / p ) at center-of-mass energies ranging from 3.8 GeV or the production threshold to 5.5 / 6.0 / 7.0 GeV have been measured via initial-state radiation. The cross sections for the processes e + e − → π + π − J / ψ and e + e − → K + K − J / ψ are consistent with previously published results. The cross sections for these channels obtained by combining with previous Belle results are also given. The process e + e − → p p ¯ J / ψ is investigated for the first time. The yields are small and no significant structure is observed in the cross section versus energy. Searches for vector charmoniumlike states in the h + h − J / ψ systems, and for associated intermediate states in the h ± J / ψ systems, are also presented.