We report a measurement of the Lambda(b)(0) lifetime using a sample corresponding to 1.3 fb(-1) of data collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. ...The Lambda(b)(0) baryon is reconstructed via the decay Lambda(b)(0)-->micronuLambda(c)(+)X. Using 4437+/-329 signal candidates, we measure the Lambda(b)(0) lifetime to be tau(Lambda(b)(0))=1.290(-0.110)(+0.119)(stat)(-0.091)(+0.087)(syst) ps, which is among the most precise measurements in semileptonic Lambda(b)(0) decays. This result is in good agreement with the world average value.
Properties of L=1 B(1) and B(2) mesons Ancu, L S; Anderson, S; Arov, M ...
Physical review letters,
2007-Oct-26, 20071026, 2007-10-26, Letnik:
99, Številka:
17
Journal Article
Recenzirano
This Letter presents the first strong evidence for the resolution of the excited B mesons B(1) and B(2)* as two separate states in fully reconstructed decays to B(+)(*)pi(-). The mass of B(1) is ...measured to be 5720.6+/-2.4+/-1.4 MeV/c(2) and the mass difference DeltaM between B(2)* and B(1) is 26.2+/-3.1+/-0.9 MeV/c;{2}, giving the mass of the B(2)* as 5746.8+/-2.4+/-1.7 MeV/c(2). The production rate for B(1) and B(2)* mesons is determined to be a fraction (13.9+/-1.9+/-3.2)% of the production rate of the B+ meson.
We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrts = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence ...for signal, we exclude most regions of the ( M(H+/-),tan(beta)) parameter space where the decay t--> H(+)b has a branching fraction >0.36 and B(H+/--->tau(nu)(tau)) is large.
We have measured the Lambda b lifetime using the exclusive decay Lambda b --> J/psi Lambda, based on 1.2 fb(-1) of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda ...b decays, where the J/psi and Lambda are identified via the decays J/psi --> mu+ mu- and Lambda --> ppi, we measured the Lambda b lifetime to be tau(Lambda b)=1.218 (+0.130)/(-0.115) (stat) +/- 0.042(syst) ps. We also measured the B0 lifetime in the decay B0 --> J/psi(mu+ mu-)K(0)/(S)(pi+ pi-) to be tau(B0)=1.501 (+0.078)/(-0.074) (stat) +/- 0.050(syst) ps, yielding a lifetime ratio of tau(Lambda b)/tau(B0)=0.811 (+0.096)/(-0.087) (stat) +/- 0.034(syst).
Long-lived, heavy particles are predicted in a number of models beyond the standard model of particle physics. We present the first direct search for such particles' decays, occurring up to 100 h ...after their production and not synchronized with an accelerator bunch crossing. We apply the analysis to the gluino (g), predicted in split supersymmetry, which after hadronization can become charged and lose enough momentum through ionization to come to rest in dense particle detectors. Approximately 410 pb(-1) of pp collisions at square root(s) = 1.96 TeV collected with the D0 detector during Run II of the Fermilab Tevatron collider are analyzed in search of such "stopped gluinos" decaying into a gluon and a neutralino (chi(1)(0)). Limits are placed on the (gluino cross section) x (probability to stop) x BR(g --> g chi(1)(0)) as a function of the gluino and chi(1)(0) masses, for gluino lifetimes from 30 micros-100 h.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract A measurement of the ... cross section in pp collisions at ... TeV is presented, using data corresponding to an ...integrated luminosity of 5.0 fb^sup -1^ collected with the CMS detector. This measurement is based on the observation of events with an imbalance of transverse energy in excess of 130 GeV and a single photon in the absolute pseudorapidity range |eta|<1.4 with transverse energy above 145 GeV. The ... production cross section is measured to be 21.1±4.2 (stat.)±4.3 (syst.)±0.5 (lum.) fb, which agrees with the standard model prediction of 21.9±1.1 fb. The results are combined with the CMS measurement of Zγ production in the ^sup +^ ^sup -^ γ final state (where is an electron or a muon) to yield the most stringent limits to date on triple gauge boson couplings: ..., ... for ZZγ and ..., ... for Zγγ couplings. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract The W-boson helicity fractions in top-quark decays are measured with ... events in the lepton+jets final state, ...using proton-proton collisions at a centre-of-mass energy of 7 TeV, collected in 2011 with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5.0 fb^sup -1^. The measured fractions of longitudinal, left-, and right-handed helicity are F ^sub 0^ = 0.682 ± 0.030 (stat.) ± 0.033 (syst.), F ^sub L^ = 0.310 ± 0.022 (stat.) ± 0.022 (syst.), and F ^sub R^ = 0.008 ± 0.012 (stat.) ± 0.014 (syst.), consistent with the standard model predictions. The measured fractions are used to probe the existence of anomalous Wtb couplings. Exclusion limits on the real components of the anomalous couplings g ^sub L^ , g ^sub R^ are also derived. Figure not available: see fulltext.
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