We present constraints on models containing non-standard-model values for the spin J and parity P of the Higgs boson H in up to 9.7 fb(-1) of pp collisions at sqrts = 1.96 TeV collected with the D0 ...detector at the Fermilab Tevatron Collider. These are the first studies of Higgs boson J(P) with fermions in the final state. In the ZH → ℓℓbb, WH → ℓνbb, and ZH → ννbb final states, we compare the standard model (SM) Higgs boson prediction, J(P) = 0(+), with two alternative hypotheses, J(P) = 0(-) and J(P) = 2(+). We use a likelihood ratio to quantify the degree to which our data are incompatible with non-SM J(P) predictions for a range of possible production rates. Assuming that the production rate in the signal models considered is equal to the SM prediction, we reject the J(P) = 0(-) and J(P) = 2(+) hypotheses at the 97.6% CL and at the 99.0% CL, respectively. The expected exclusion sensitivity for a J(P) = 0(-) (J(P) = 2(+)) state is at the 99.86% (99.94%) CL. Under the hypothesis that our data are the result of a combination of the SM-like Higgs boson and either a J(P) = 0(-) or a J(P) = 2(+) signal, we exclude a J(P) = 0(-) fraction above 0.80 and a J(P) = 2(+) fraction above 0.67 at the 95% CL. The expected exclusion covers J(P) = 0(-) (J(P) = 2(+)) fractions above 0.54 (0.47).
The pair production of W and Z bosons at centre-of-mass energy from 161 GeV to 196 GeV is measured using the ALEPH detector at LEP. WW cross sections are given for different topologies of W decays ...into leptons and hadrons. ZZ cross sections are also given including all possible ZZ final states.
We present a measurement of the W boson mass using data corresponding to 4.3 fb(-1) of integrated luminosity collected with the D0 detector during Run II at the Fermilab Tevatron pp collider. With a ...sample of 1,677,394 W → eν candidate events, we measure M(W) = 80.367 ± 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1 fb(-1) of integrated luminosity, to yield M(W) = 80.375 ± 0.023 GeV.
We present evidence for the exotic charged charmoniumlike state Z(c)(+/-)(3900) decaying to J/psi pi(+/-) in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent ...J/psi pi(+)pi(-) system in the invariant-mass range 4.2-4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4 fb(-1) of p (p) over bar collision data collected by the D0 experiment at the Fermilab Tevatron collider.
We report evidence for the simultaneous production of J/ψ and ϒ mesons in 8.1 fb^{-1} of data collected at sqrts=1.96 TeV by the D0 experiment at the Fermilab ppover ¯ Tevatron Collider. Events ...with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σ_{eff}=2.2±0.7(stat)±0.9(syst) mb.
Improved determination of the width of the top quark Adams, T.; Alexeev, G. D.; Åsman, B. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
05/2012, Letnik:
85, Številka:
9
Journal Article
Recenzirano
Odprti dostop
We present an improved determination of the total width of the top quark, Gammat, using 5.4 fb super(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron pp Collider. The ...total width Gammat is extracted from the partial decay width Gamma(t arrow right Wb) and the branching fraction B(t arrow right Wb). Gamma(t arrow right Wb) is obtained from the t-channel single top-quark production cross section and B(t arrow right Wb) is measured in tt events. For a top mass of 172.5 GeV, the resulting width is Gammat= (ProQuest: Formulae and/or non-USASCII text omitted) GeV. This translates to a top-quark lifetime of taut = (ProQuest: Formulae and/or non-USASCII text omitted) x 10 super(-25) s. We also extract an improved direct limit on the Cabibbo-Kobayashi-Maskawa quark-mixing matrix element 0.81 < Vtb < or = 1 at 95% C.L. and a limit of Vtb' < 0.59 for a high-mass fourth-generation bottom quark assuming unitarity of the fourth-generation quark-mixing matrix.
We describe an analysis comparing the p¯p elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM ...Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of √s=1.96 TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4σ level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4σ and 4.6σ. The combined significance is larger than 5σ and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.
We present searches for the anomalous γWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wγ, WW, and WZ ...production with leptonic final states. The analyzed data correspond to up to 8.6fb -1 of integrated luminosity collected by the D0 detector in pp- collisions at s=1.96TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters δκ γ, λ, and δg1Z for a cutoff energy scale Λ=2TeV. The combined 68% C.L. limits are -0.057&lt;δκ γ&lt;0.154, -0.015&lt;λ&lt;0.028, and -0.008&lt;δg1Z&lt;0.054 for the LEP parameterization, and -0.007&lt;δκ&lt;0.081 and -0.017&lt;λ&lt;0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.
Using 7.3 fb⁻¹ of pp collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable φ(η)*, which probes the same physical effects as the Z/γ* boson ...transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the φ(η)* distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.
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