14 research outputs found

    Measurement of the CP-violating phase ϕs_{s} in the B0^{0}s_{s}→J/ψ φ(1020) →ΌâșΌ⁻KâșK⁻ channel in proton-proton collisions at √s = 13 TeV

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    Observation of electroweak production of Wγ with two jets in proton-proton collisions at √s = 13 TeV

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    A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1^{-1}. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak Wγjj_{γjj} production in a restricted fiducial region is measured as 20.4 +/- 4.5 fb and the total cross section for Wγ_{γ} production in association with 2 jets in the same fiducial region is 108 +/- 16 fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

    Measurements of production cross sections of polarized same-sign W boson pairs in association with two jets in proton-proton collisions at s=13 TeV

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    The first measurements of production cross sections of polarized same-sign W±W±boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137fb−1. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±W±scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88)fbis set on the production cross section for longitudinally polarized same-sign W±W±boson pairs. The electroweak production of same-sign W±W±boson pairs with at least one of the Wbosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations.SCOAP

    Differences between electrons and positrons interacting with detector material

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    A theory of multiple scattering, exhibiting differences between electrons and positrons in interactions with matter, is developed. Additional differences in stopping power and annihilation for positrons are briefly discussed. Experimental verification of these differences is reported for plastic scintillators and Si(Li) detectors, which are gradually changed from a full-energy (E) detector towards an energy-loss (DELTA-E) detector by a variation of the incident electron and positron energy

    Positron-electron pair spectrometry with selective mini-orange devices

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    Pair spectrometers have been developed with mini-orange filters and adapted Si(Li) detectors. They have been employed in searches for resonant Bhabha scattering and viable axions. They are of implicit value for studies of pair creation with the high resolution of solid state detectors, with the high acceptance of mini-orange filters and with high specificity for recognition of e+e-pairs. The latter is due to the first-order magnetic focusing and can be further enhanced (optional) by observation of annihilation quanta after detection of a positron. Special emphasis is devoted to a fourfold arrangement for Bhabha spectrometry, introducing coincident e+e--pair observations with a central four-segmented Si(Li) detector for electrons,and four Si(Li) counters in sideways positions for detection of correlated positrons

    Search for resonant Bhabha scattering around an invariant mass of 1.8 MeV

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    A search was made for resonant Bhabha scattering of positrons on atomic electrons using two Mini-Orange spectrometers and relatively thick targets of low Z. No resonances were found within (trre~ F) limits of -~20 to 40 barn eV for lifetimes in the 10- ~o_ 10- ~ 2 s range of an intermediate particle propagating freely in the target material

    Pretoriana, no. 032 & 033, April-Aug. 1960

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    Ons vier = We rejoice / G.W. Eybers -- 'n Leemte in die geskiedskrywer se benadering van ons geskiedenis = A defect in the historians approach to our history / J.C. Otto -- Woord van waardering aan Dr. Spies / W. Punt -- How Pretoria became seat of Government of the South African Republic in 1860 and administrative capital of the Union of South Africa in 1910 / J.D. Bodel -- Die stigting van Pretoria en die voorsiening van gewone en godsdiensonderwys tot 1 November 1859 -- Pretoria's first government school / J. Ploeger -- When the wild cat was hunted on Church Square / W.J. de Kock -- Die munisipale bestuursreëlings van Pretoria voor 1877 / J.J.N. Cloete -- Die aandeel van Willem Skinner in die ontwikkeling van Pretoria / S.G. Roos -- Charles John Beanes / R.E. Kuiper -- Church Square / C.J. Beanes -- Burgerspark / J.P. Engelbrecht -- John Hunter McLea, Pretoria se eerste Direkteur van Parke / H.M. Rex -- Meester Wessel Louis se skool in Pretoria / S.J. Bezuidenhout -- Die Staatsbiblioteek , 1883-1900 / Steph. J. Schoeman -- Die Staatsmodelskool is 'n sieraad van die 19e eeuse argitektuur / F.C. Calitz -- Die Staatsmodelskool as historiese gedenkwaardigheid geproklameer -- Die Staatsmodelskool / C.H.B. Naudé -- Sir Winston Churchill and Pretoria sixty years ago / A.M. Davey -- Die glasblasery op Eerste Fabrieken / J. Ploeger -- Uit die briewe van Arnold Theiler V / F.J. du T. Spies -- 'n Historiese skildery in die Ou Museum / P.J. Nell -- Voortrekkerhoogte : 'n geskiedkundige oorsig / J.C.D. Lamprecht -- Pretoria se eerste Uniedag / F.J. du T. Spies -- Die Uniegebou / A.L. Meiring -- Die Pretoriase stadsaal / W.J. Erasmus -- Bekende Helde-akker van Suid-Afrika / W.J. de Kock -- 'n Voorstel vir die uitleg van 'n wandelterrein in Pretoria / T.H. le Roux -- 'n Wandelterrein vir die stad Pretoria / Franz J. Wepener -- John or Jahn Street in Muckleneuk? / A.M. Davey -- Gelukwensings=Congratulations -- 'n Woord van dankOriginal copy bound without p. 111-112 ; p. 109-110 duplicate

    Observation of electroweak production of WÎł with two jets in proton-proton collisions at s=13 TeV

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    © 2020 The Author(s)A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak WÎłjj production in a restricted fiducial region is measured as 20.4±4.5fb and the total cross section for WÎł production in association with 2 jets in the same fiducial region is 108±16fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators

    Search for supersymmetry in proton-proton collisions at <mml:msqrt>s</mml:msqrt>=13 TeV in events with high-momentum Z bosons and missing transverse momentum

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    A search for new physics in events with two highly Lorentz-boosted Z bosons and large missing transverse momentum is presented. The analyzed proton-proton collision data, corresponding to an integrated luminosity of 137 fb(-1), were recorded at s = 13 TeV by the CMS experiment at the CERN LHC. The search utilizes the substructure of jets with large radius to identify quark pairs from Z boson decays. Backgrounds from standard model processes are suppressed by requirements on the jet mass and the missing transverse momentum. No significant excess in the event yield is observed beyond the number of background events expected from the standard model. For a simplified supersymmetric model in which the Z bosons arise from the decay of gluinos, an exclusion limit of 1920 GeV on the gluino mass is set at 95% confidence level. This is the first search for beyond-standard-model production of pairs of boosted Z bosons plus large missing transverse momentum

    Measurement of the CP-violating phase phi(s) in the B-s(0) -> J/psi phi(1020) -> mu(+)mu-K+K- channel in proton-proton collisions at root s=13 TeV

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    The CP-violating weak phase ?s and the decay width difference ??s between the light and heavy B0s mass eigenstates are measured with the CMS detector at the LHC in a sample of 48 500 reconstructed B0s? J/I) d (1020) ?11+11? K+K? events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4 fb?1, collected in proton-proton collisions at ?s = 13 TeV in 2017?2018. To extract the values of ?s and ??s, a time-dependent and flavor-tagged angular analysis of the 11+11?K+K? final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ?s = ?11 ?50 (stat) ? 10 (syst) mrad and ??s = 0.114 ? 0.014 (stat)? 0.007 (syst) ps?1, in agreement with the standard model predictions. When combined with the previous CMS measurement at ?s = 8 TeV, the following values are obtained: ?s = ?21 ? 44 (stat) ? 10 (syst) mrad, ??s = 0.1032 ? 0.0095 (stat) ? 0.0048 (syst) ps?1, a significant improvement over the 8 TeV result. ? 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY licens
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