A search for decays of the Higgs boson into a pair of new spin-zero particles, H→aa, where the a-bosons decay into a b-quark pair and a muon pair, is presented. The search utilizes 36.1 fb-1 of ...proton–proton collision data at $\sqrt{s}$ = 13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% confidence level are placed on the branching ratio (δH/δSM) x $\mathcal{B(H→aa→bbμμ)}$, ranging from 1.2 10-4 to 8.4 x 10-4 in the a-boson mass range of 20–60 GeV. Model-independent limits are set on the visible production cross-section times the branching ratio to the bbμμ final state for new physics, δVIS(X) x $\mathcal{B(X→bbμμ)}$, ranging from 0.1 fb to 0.73 fb for mμμ between 18 and 62 GeV.
The layer 0 inner silicon detector of the D0 experiment Angstadt, R.; Bagby, L.; Bean, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2010, Letnik:
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This paper describes the design, fabrication, installation and performance of the new inner layer called Layer 0 (L0) that was inserted in the existing Run IIa silicon micro-strip tracker (SMT) of ...the D0 experiment at the Fermilab Tevatron p¯p collider. L0 provides tracking information from two layers of sensors, which are mounted with center lines at a radial distance of 16.1 and 17.6mm from the beam axis. The sensors and read-out electronics are mounted on a specially designed and fabricated carbon fiber structure that includes cooling for sensor and read-out electronics. The structure has a thin polyimide circuit bonded to it so that the circuit couples electrically to the carbon fiber allowing the support structure to be used both for detector grounding and a low impedance connection between the remotely mounted hybrids and the sensors.
We report results of a search for supersymmetry (SUSY) with gauge-mediated symmetry breaking in di-photon events collected by the DO experiment at the Fermilab Tevatron Collider in 2002-2006. In 1.1 ...fb(-1) of data, we find no significant excess beyond the background expected from the standard model and set the most stringent lower limits to date for a standard benchmark model on the lightest neutralino and chargino masses of 125 GeV and 229 GeV, respectively, at 95% confidence.
We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the tt¯ cross section measured in the lepton + jets channel in pp¯ collisions at s=1.96 TeV using 5.3 ...fb−1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and MS¯ mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic B-s(0) decays A(SL)(s,unt) by comparing the decay rate of B-s(0) -> mu(+) ...D-s(-) nu X, where D-s(-) -> phi pi(-) and phi -> K+K-, with the charge-conjugate (B) over bar (0)(s) decay rate. This sample was selected from 1: 3 fb(-1) of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain A(SL)(s,unt) = 1.23 +/- 0.97(stat) +/- 0.17(syst) x 10(-2). Assuming that Delta m(s)/(Gamma) over bar (s) >> 1, this result can be translated into a measurement of the CP-violating phase in B-s(0) mixing: Delta Gamma(s)/Delta m(s) tan phi(s) = 2.45 +/- 1.93(stat) +/- 0.35(syst) x 10(-2).
The latest results from the DØ Collaboration on top quark production and properties in p collisions at a center of mass energy of 1.96 TeV are presented. The measurements were performed using ...approximately 1 fb-1 of Dø data taken during Run II at the Tevatron.
The results of a search for squarks and gluinos using data from p (p) over bar collisions recorded at a center-of-mass energy of 1.96 TeV by the DO detector at the Fermilab Tevatron Collider are ...reported. The topologies analyzed consist of acoplanar-jet and multijet events with large missing transverse energy. No evidence for the production of squarks or gluinos was found in a data sample of 310pb(-1). Lower limits of 325 and 241 GeV were derived at the 95% C.L. on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan beta=3, A(0) = 0, and mu < 0.
We present a model-independent measurement of t-channel electroweak production of single top quarks in pp¯ collisions at s=1.96 TeV. Using 5.4 fb−1 of integrated luminosity collected by the D0 ...detector at the Fermilab Tevatron Collider, and selecting events containing an isolated electron or muon, missing transverse energy and one or two jets originating from the fragmentation of b quarks, we measure a cross section σ(pp¯→tqb+X)=2.90±0.59(stat+syst) pb for a top quark mass of 172.5 GeV. The probability of the background to fluctuate and produce a signal as large as the one observed is 1.6×10−8, corresponding to a significance of 5.5 standard deviations.
We measure the correlation between the spin of the top quark and the spin of the anti-top quark in tt¯→W+bW−b¯→ℓ+νbℓ−ν¯b¯ final states produced in pp¯ collisions at a center of mass energy s=1.96 ...TeV, where ℓ is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb−1 and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and t¯ rest frames, yielding a correlation strength C=0.10−0.45+0.45, in agreement with the NLO QCD prediction within two standard deviations, but also in agreement with the no correlation hypothesis.
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