The color evaporation model simply states that charmonium production is described by the same dynamics as
D
D
production, i.e., by the formation of a colored
c
c
pair. Its color happens to be ...bleached by soft final-state interactions. We show that the model gives a complete picture of charmonium production including low-energy production by proton, photon and antiproton beams, and high-energy production at the Tevatron and HERA.
Search for the rare decay Bs0→μ+μ Adams, M.; Alexeev, G.D.; Alton, A. ...
Physics letters. B,
10/2010, Letnik:
693, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We present the results of a search for the flavor changing neutral current decay Bs0→μ+μ− using 6.1 fb−1 of pp¯ collisions at s=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron ...Collider. The observed number of Bs0 candidates is consistent with background expectations. The resulting upper limit on the branching fraction is B(Bs0→μ+μ−)<5.1×10−8 at the 95% C.L. This limit is a factor of 2.4 better than that of the previous D0 analysis and the best limit to date.
We point out that an unorthodox way to describe the production of rapidity gaps in deep inelastic scattering, recently proposed by Buchmüller and Hebecker, suggests a description of the production of ...heavy quark bound states which is in agreement with data. The approach questions the conventional treatment of the color quantum number in perturbative QCD.
The D0 Collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual ...single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb−1 of pp¯ collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14−0.80+0.94 pb for the t-channel and 1.05±0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.
We study WW and WZ production with lvqq (l = e, mu) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to 4.3 fb(-1) of integrated luminosity from p ...(p) over bar collisions at root s = 1.96 TeV. Assuming the ratio between the production cross sections sigma(WW) and sigma(WZ) as predicted by the standard model, we measure the total WV (V = W, Z) cross section to be sigma(WV) = 19.6(-3.0)(+3.2) pb and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use b-jet discrimination to separate the WZ component from the dominant WW component. Simultaneously fitting WW and WZ contributions, we measure sigma(WW) = 15.9(-3.2)(+3.7) pb and sigma(WZ) = 3.3(-3.3)(+4.1) pb, which is consistent with the standard model predictions.
Measurements of the inelastic photoproduction of charmonium at HERA have ignited a new charmonium crisis. The Color Singlet approach to computing onium production cross sections fits the data for ...large charmonium energy fraction
z, where color octet models fail. This approach is however in qualitative disagreement with a wealth of information that exist on charmonium production by other initial states. We here suggest that the source of the discrepancy between color octet models (whether implemented in the soft color or NRQCD formalism) and data is due to the neglect of non-perturbative effects. Implementing these in a scheme originally developed for Drell–Yan phenomenology, we illustrate how agreement with the data is achieved.
We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by ...the D0 detector at a p (p) over bar center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R-1 > 260 GeV in a minimal UED model.
We report results from searches for neutral Higgs bosons produced in p{bar p} collisions recorded by the D0 experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral ...Higgs boson in the {tau}{tau} final state and in association with a b quark in the b{tau}{tau} and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300 GeV. We exclude tan {beta} > 20-30 for Higgs boson masses below 180 GeV. These are the most stringent constraints on MSSM Higgs boson production in p{bar p} collisions.
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