K. Maeshima

We report measurements of the two-photon processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{K}^{+}{K}^{\ensuremath{-}}$, at an ${e}^{+}{e}^{\ensuremath{-}}$ center-of-mass energy of 29 GeV. In the ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ data a high-statistics analysis of the $f(1270)$ results in a $\ensuremath{\gamma}\ensuremath{\gamma}$ width $\ensuremath{\Gamma}(\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}f)=3.2\ifmmode\pm\else\textpm\fi{}0.4$ keV. The ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ continuum below the $f$ mass is well described by a QED Born approximation, whereas above the $f$ mass it is consistent with a QCD-model calculation if a large contribution from the $f$ is assumed. For the ${K}^{+}{K}^{\ensuremath{-}}$ data we find agreement of the high-mass continuum with the QCD prediction; limits on ${f}^{\ensuremath{'}}(1520)$ and $\ensuremath{\theta}(1720)$ formation are presented.

The ratio $R$ of the cross section for ${e}^{+}{e}^{\ensuremath{-}}$ annihilation into hadronic final states to the QED cross section for muon-pair production is measured to be 4.34\ifmmode\pm\else\textpm\fi{}0.45\ifmmode\pm\else\textpm\fi{}0.30 and 4.23\ifmmode\pm\else\textpm\fi{}0.20\ifmmode\pm\else\textpm\fi{}0.21 at c.m. energies of 50 and 52 GeV, respectively. From these values of $R$ and an analysis of the event shapes we deduce a 95%-confidence-level upper limit for the production rate of new heavy charge $+\frac{2}{3}e$ or $\ensuremath{-}\frac{1}{3}e$ quarks to be 0.19 units of $R$.

We present the general properties of multihadron final states produced by ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at center-of-mass energies from 52 to 57 GeV in the AMY detector at the KEK collider TRISTAN. Global shape, inclusive charged-particle, and particle-flow distributions are presented. Our measurements are compared with QCD+fragmentation models that use either leading-logarithmic parton-shower evolution or QCD matrix elements at the parton level, and either string or cluster fragmentation for hadronization.

The multiplicities per event of π± and K± are measured separately for e+e- annihilation into cc, bb, and light quark pairs at Ecm=29 GeV. The K± multiplicity is higher for heavy quark events than for light quark events. The π± multiplicity and the π± scaled differential cross section at low x=Ebeam/Ebeam are found to be higher for bb events than for other events.

We present evidence for the non-Abelian nature of QCD from a study of multijet events produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations from \ensuremath{\surd}s =50 to 57 GeV in the AMY detector at the KEK storage ring TRISTAN. A comparison of the three-jet event fraction at TRISTAN to the fraction of the DESY storage ring PETRA shows that the QCD coupling strength ${\ensuremath{\alpha}}_{s}$ decreases with increasing ${Q}^{2}$. In addition, measurements of the angular distributions of four-jet events show evidence for the triple-gluon vertex.

We present results of an experimental study of e+e−+ hadrons in the kinematic regime for which the process is interpreted as hadron production in collisions of almost-real photons. The data sample corresponds to an integrated luminosity of 27.5 pb− and covers center-of-mass energies from 55 to 61.4 GeV. We observe more events than expected from the incoherent sum of quark-parton and vector-meson-dominance models, and we give a quantitative explanation of the excess by including the hard scattering of the hadronic constituents of the photons calculated with QCD.

Inelastic and elasticJ/ψ (3097) photoproduction on Li6 are measured at a mean γ energy of 90 GeV in an open spectrometer. TheJ/ψ are identified by their decays intoμ + μ − ore + e −. A signal of ψ′(3685) intoμ + μ − andJ/ψπ + π − is also seen. The inelastic cross-section withZ=E ψ/Eγ<0.9 is compared in shape and magnitude with the colour singlet model of photon-gluon fusion.

We present the charged-particle multiplicity distributions for ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at center-of-mass energies from 50 to 61.4 GeV. The results are based on a data sample corresponding to a total integrated luminosity of 30 ${\mathrm{pb}}^{\ensuremath{-}1}$ obtained with the AMY detector at the KEK storage ring TRISTAN. The charged-particle multiplicity distributions deviate significantly from the modified Poisson and pair Poisson distributions, but follow Koba-Nielsen-Olesen scaling and are well reproduced by the LUND parton-shower model.

Results are presented on the exclusive production of four-prong final states in photon-photon collisions from the TPC/Two-Gamma detector at the SLAC ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring PEP. Measurement of dE/dx and momentum in the time-projection chamber (TPC) provides identification of the final states 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, ${K}^{+}$${K}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, and 2${K}^{+}$2${K}^{\mathrm{\ensuremath{-}}}$. For two quasireal incident photons, both the 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ and ${K}^{+}$${K}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ cross sections show a steep rise from threshold to a peak value, followed by a decrease at higher mass. Cross sections for the production of the final states ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$, ${\ensuremath{\rho}}^{0}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, and \ensuremath{\varphi}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ are presented, together with upper limits for \ensuremath{\varphi}${\ensuremath{\rho}}^{0}$, \ensuremath{\varphi}\ensuremath{\varphi}, and ${K}^{\mathrm{*}0}$K\ifmmode\bar\else\textasciimacron\fi{} $^{\mathrm{*}0}$. The ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ contribution dominates the four-pion cross section at low masses, but falls to nearly zero above 2 GeV. Such behavior is inconsistent with expectations from vector dominance but can be accommodated by four-quark resonance models or by t-channel factorization. Angular distributions for the part of the data dominated by ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ final states are consistent with the production of ${J}^{P}$${=2}^{+}$ or ${0}^{+}$ resonances but also with isotropic (nonresonant) production. When one of the virtual photons has mass (${m}_{\ensuremath{\gamma}}^{2}$=-${Q}^{2}$\ensuremath{\ne}0), the four-pion cross section is still dominated by ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ at low final-state masses ${W}_{\ensuremath{\gamma}\ensuremath{\gamma}}$ and by 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ at higher mass. Further, the dependence of the cross section on ${Q}^{2}$ becomes increasingly flat as ${W}_{\ensuremath{\gamma}\ensuremath{\gamma}}$ increases.

By observing the reaction γγ→Ks0K±π∓, the TPC/Two-Gamma experiment at the SLAC e+e− storage ring PEP has obtained a 95%-confidence-level limit of Γι→γγB(ι→KK¯π)<1.6 keV for the ι(1450) meson. If, as is likely, the ι decays predominantly into KK¯π, the resulting Γι→γγ limit appears to conflict with previous assignments of an observed ργ decay to ι and also with many analyses of η-η’-ι mixing. The contrast of this small γγ width with the large rate for J/ψ→γι is evidence that the ι is a glueball with little admixture of qq¯ states.Received 6 March 1986DOI:https://doi.org/10.1103/PhysRevLett.57.51©1986 American Physical Society

We compare the particle flow in the event plane of three-jet $q\overline{q}g$ (quark-antiquark-gluon) events with the particle flow in radiative annihilation events $q\overline{q}\ensuremath{\gamma}$ (quark-antiquark-photon) for similar kinematic configurations. In the angular region between quark and antiquark jet, we find a significant decrease in particle density for $q\overline{q}g$ as compared to $q\overline{q}\ensuremath{\gamma}$. This effect is predicted in QCD as a result of destructive interference between soft-gluon radiation from quark, antiquark, and hard gluon.

The structure function Fγ2 for a quasireal photon has been measured in the reaction ee→eeX for Q2 in the range 0.2<Q2<7 GeV2, by use of 9200 multihadron events obtained with the TPC/Two-Gamma detector at the SLAC storage ring PEP. The data have been corrected for detector effects by a regularized unfolding procedure and are presented as Fγ2(x,Q2). The structure function shows scaling in the region 0.3<Q2<1.6 GeV2, x<0.3, and rises for higher Q2 and x>0.1. Below Q2=0.3 GeV2, scaling breaks down in accordance with the finite cross-section bound for real photons.Received 3 September 1986DOI:https://doi.org/10.1103/PhysRevLett.58.97©1987 American Physical Society

The photon structure function F2 has been measured at average Q2 values of 73,160 and 390 (GeVc)2. We compare the x dependence of the Q2 = 73 (GeVc)2 data with theoretical expectations based on QCD. In addition we present results on the Q2 evolution of the structure function for the intermediate x range (0.3⩽ x ⩽0.8). The results are consistent with QCD.

We report measurements of two-particle correlations in rapidity space between a p¯ or Λ¯ and an additional p, p¯, Λ, or Λ¯. We find evidence for local conservation of baryon number, and for the first time observe a pronounced anticorrelation between baryons with the same value of baryon number. Such an anticorrelation is expected in fragmentation models where the rapidity order of particles closely reflects their ''color order,'' as is the case, for example, in recent versions of the Lund string model.Received 14 October 1986DOI:https://doi.org/10.1103/PhysRevLett.57.3140©1986 American Physical Society

The total hadronic cross section for virtual photon-photon interactions is reported for center-of-mass energy, W, between 2 and 20 GeV. The data were obtained via the process ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\gamma}}^{\mathrm{*}}$${\ensuremath{\gamma}}^{\mathrm{*}}$\ensuremath{\rightarrow}e $^{+}e^{\mathrm{\ensuremath{-}}}$+hadrons with both scattered ${e}^{+}$ and ${e}^{\mathrm{\ensuremath{-}}}$ detected. Each photon's four-momentum squared, ${q}^{2}$, ranges from -0.1 to -1.6 ${\mathrm{GeV}}^{2}$. Dependence upon ${q}^{2}$ agrees with a generalized vector-meson-dominance model. The total cross section shows little W dependence, averaging 125 nb at ${q}_{1}^{2}$=${q}_{2}^{2}$=-0.3. Photon helicity interference terms are determined.

We present the first results on inclusive photo-production of prompt photons at high transverse momenta. The data were taken in an open spectrometer at CERN using a high intensity photon beam energy between 50 and 150 GeV. After subtracting the yield of photons from indirect sources, a clear excess is observed for transverse momenta above 2.5 GeVc Deep inelastic Compton scattering with appropriate QCD corrections account for this excess. The data disfavour the gauge integer charge quark models so far proposed.

The total cross section for e+e− annihilation into hadrons has been measured for CM energies ranging from 50 to 57 GeV. We fit the predictions of the standard model to these measurements and those at lower energies. The mass of the Z0 boson, MZ, and the QCD scale parameter, ΛMS, are derived from the fit. The results are MZ=88.6−1.8+2.0 GeV/c2, and ΛMS=0.15−0.11+0.16 GeV.

The first results on inclusive photoproduction of π0 at transverse momenta up to 4 GeV/c, using incident γ energies between 50 and 150 GeV are presented. A comparison is made with inclusive π0 production obtained, in the same experiment, with incident π−. Using the π− data to parametrize the hadronic behaviour of the photon, significant differences are observed in quantitative agreement with QCD Compton scattering and corrections thereof.

Multihadronic e+e− annihilation events containing final-state leptons have been investigated with a 4.7-pb−1 data sample at c.m. energies of 50 and 52 GeV. The number of low-thrust events (T≤0.8) with isolated leptons is consistent with the expectation of the standard model with five quark flavors. Limits on the production of new quarks and leptons are reported.Received 29 December 1987DOI:https://doi.org/10.1103/PhysRevLett.60.2359©1988 American Physical Society

Three-jet events produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations are used to provide comparisons between quark and gluon jets. Differences between quark-induced and gluon-induced jets are observed. Quark jets tend to have a more tightly collimated structure than gluon jets, which is reflected in the concentration of a larger fraction of the jet's energy near the jet axis.

Measurements of the differential cross sections for e+e−→μ+μ− and e+e−→τ+τ− at values of s from 52 to 57 GeV are reported. The forward-backward asymmetries and the total cross sections for these reactions are found to be in agreement with predictions of the standard model of the electro-weak interactions. These measurements are used to extract values of the weak coupling constant gvegvl and gAegAl, where l = μ or τ.

The ratio $R$ of the total cross section for ${e}^{+}{e}^{\ensuremath{-}}$ annihilation into hadrons to the lowest-order QED cross section for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ has been measured for center-of-mass energies ranging from 50 to 61.4 GeV. If we allow for an overall shift of ---4.9%, about 1.5 times our estimated normalization error, the results are consistent with the standard-model predictions.

An analysis of the production of muon pairs in γγ collisions is presented. The leptonic structure functions of the photon, F2 and 2xF1, are extracted for Q2 < 1.7 GeV2. Their x dependences agree well with QED predictions. Corrections are required to eliminate radiative effects in the 2xF1 data.

QED processes up to O(α4) have been studied at center-of-mass energies between 50 and 57 GeV using the AMY detector at TRISTAN. A possible substructure of the electron and muon is investigated in terms of chiral invariant contact interactions and also in terms of excited lepton production. The differential cross section data for e+e−→e+e− are consistent with the standard model at a confidence level of only 3.5%. From the absence of excited lepton production, we establish new upper limits on the coupling to excited electrons of mass up to 56 GeV/c2 and on the coupling to excited muons of mass up to 52 GeV/c2.

Two-photon formation of the η' in the reaction e+e−→e+e−ηm'→e+e−π+π−γ has been studied for nearly real and virtual photons at an e+e− center-of-mass energy of 29 GeV. The γγ width of the η' is found to be 4.5±0.3(stat.)±0.7(syst.) keV. The measured dependence of this γγ width upon the photon four-momentum squared in the range 0–5 GeV2 agrees with predictions both from QCD and from ρ dominance. A spin analysis results in a strong preference for a spin-zero, relative to a spin-two, assignment for the η'. No evidence for C-parity violation is found in this η'→π+π−γ decay mode.Received 15 December 1986DOI:https://doi.org/10.1103/PhysRevD.35.2650©1987 American Physical Society

We measure an inclusive branching fraction of (13.9 ± 2.0+1.9−2.2)% for the decay τ−→ντπ−π0+nh0(n>~1), where h0 is a π0 or an η. The data sample, obtained with the time-projection-chamber detector facility at the SLAC e+e− storage ring PEP, corresponds to an integrated luminosity of 72 pb−1 at 29 GeV center-of-mass energy. The measured branching fraction is somewhat greater than the theoretical prediction and, with errors taken into account, could resolve the present difference between the inclusive and the sum of the exclusive τ± branching fractions into one charged prong.Received 1 July 1986DOI:https://doi.org/10.1103/PhysRevLett.57.1836©1986 American Physical Society

Searches for the pair production of the supersymmetric partner particles of leptons, quarks, and non-minimal Higgs have been made in e +e − annihilations at center-of-mass energies between 50 and 60.8 GeV using the AMY detector at TRISTAN. No evidence for their existence is observed and 95% CL mass limits are presented.

Using 123 multihadronic inclusive muon-production ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation events at an average c.m. energy of 55.2 GeV, we extracted the forward-backward charge asymmetry of the ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}bb\ifmmode\bar\else\textasciimacron\fi{} process and the R ratio for bb\ifmmode\bar\else\textasciimacron\fi{} production. We used an analysis method in which the behavior of the c quark and lighter quarks is assumed, with only that of the b quark left indeterminate. The results, ${A}_{b}$=-0.72\ifmmode\pm\else\textpm\fi{}0.28(stat)\ifmmode\pm\else\textpm\fi{}0.13(syst) and ${R}_{b}$=0.57\ifmmode\pm\else\textpm\fi{}0.16\ifmmode\pm\else\textpm\fi{}0.10, are consistent with the standard model.

The Data Quality Monitoring software is a central tool in the CMS experiment. It is used in the following key environments: (i) Online, for real-time detector monitoring; (ii) Offline, for the prompt-offline-feedback and final fine-grained data quality analysis and certification; (iii) Validation of all the reconstruction software production releases; (iv) Validation in Monte Carlo productions. Though the basic structure of the Run1 DQM system remains the same for Run2, between the Run1 and Run2 periods, the DQM system underwent substantial upgrades in many areas, not only to adapt to the surrounding infrastructure changes, but also to provide improvements to meet the growing needs of the collaboration with an emphasis on more sophisticated methods for evaluating data quality. We need to cope with the higher-energy and -luminosity proton-proton collision data, as well as the data from various special runs, such as Heavy Ion runs. In this contribution, we will describe the current DQM software, structure and workflow in the different environments. We then discuss the performance and our experiences with the DQM system in Run2. The main technical challenges which we have encountered and the solutions adopted during Run2 will also be discussed, including efficient use of memory in multithreading environments. Finally, we present the prospect of a future DQM upgrade with emphasis on functionality and long-term robustness for LHC Run3.

By studying ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations in the center-of-mass energy range between 50 and 60.8 GeV, we have established a 95%-confidence-level lower limit on the mass of a fourth-generation charge -(1/3 quark b' of 27.2 GeV. In contrast with all previous searches, this limit has been obtained through consideration of the decay processes b'\ensuremath{\rightarrow}b\ensuremath{\gamma} and b'\ensuremath{\rightarrow}bg aswell as b'\ensuremath{\rightarrow}${\mathrm{cW}}^{\mathrm{\ensuremath{-}}}$. For the cases where any one of the three decay modes dominates, we obtain higher mass limits.

We report a measurement of the reaction γγ→K+K−π+π− in both tagged and untagged events at PEP. The cross section rises with invariant γγ mass to about 15 nb at 2 GeV and falls slowly at higher masses. We find clear evidence for the processes γγ→φπ+π− and γγ→K*0(892)Kπ. Upper limits (95% C.L.) of 1.5 and 5.7 nb in the mass range from 1.7 to 3.7 GeV are obtained for φρ0 and K*0K¯*0 production, respectively.Received 25 February 1985DOI:https://doi.org/10.1103/PhysRevLett.54.2564©1985 American Physical Society

The forward-backward asymmetry of quarks produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations, summed over all flavors, is measured at \ensuremath{\surd}s between 50 and 60.8 GeV. Methods of determining the charge direction of jet pairs are discussed. The asymmetry is found to agree with the five-flavor standard model.

We have constructed and operated a pressurized “tube-style” charged particle tracking detector, the inner tracking chamber, for the AMY experiment at the TRISTAN e+e− storage ring. The AMY inner tracking chamber consists of a four layer, 144 cell per layer “tube-style” drift chamber system. It occupies the region between the beam pipe and the AMY central drift chamber. An overall spatial resolution of 80 μm per layer has been obtained during the first two years of operation using argon-ethane gas at 1.45 bar for Bhabha scattering events. This article describes the design, construction, and operation of the device.

We have measured the branching ratios for several \ensuremath{\tau} decay modes. We use ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\ensuremath{\tau}}^{+}$${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$ events accumulated with the TPC/Two-Gamma facility at the SLAC ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring PEP. The data correspond to an integrated luminosity of 77 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ at a center-of-mass energy of 29 GeV. The one- and three-charged-particle inclusive branching ratios of the \ensuremath{\tau} decay are measured to be ${B}_{1}$=(84.7\ifmmode\pm\else\textpm\fi{}1.0)% and ${B}_{3}$=(15.1\ifmmode\pm\else\textpm\fi{}1.0)%, where ${B}_{1}$+${B}_{3}$ is constrained to be 99.85%. The branching ratios of the two leptonic decay modes are B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{\mathrm{\ensuremath{-}}}$ \ensuremath{\nu}${\ifmmode\bar\else\textasciimacron\fi{}}_{e}$${\ensuremath{\nu}}_{\ensuremath{\tau}}$)=(18.4\ifmmode\pm\else\textpm\fi{}1.6)% and B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$ \ensuremath{\nu}${\ifmmode\bar\else\textasciimacron\fi{}}_{\ensuremath{\mu}}$${\ensuremath{\nu}}_{\ensuremath{\tau}}$)=(17.7\ifmmode\pm\else\textpm\fi{}1.4)%. If we then assume lepton universality, we obtain B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{\mathrm{\ensuremath{-}}}$ \ensuremath{\nu}${\ifmmode\bar\else\textasciimacron\fi{}}_{e}$${\ensuremath{\nu}}_{\ensuremath{\tau}}$)=(18.3\ifmmode\pm\else\textpm\fi{}0.9)% and B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$ \ensuremath{\nu}${\ifmmode\bar\else\textasciimacron\fi{}}_{\ensuremath{\mu}}$${\ensuremath{\nu}}_{\ensuremath{\tau}}$)=(17.8\ifmmode\pm\else\textpm\fi{}0.9)%. We measure the Cabibbo-allowed semihadronic decay mode B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$+neutral particles)=(47.0\ifmmode\pm\else\textpm\fi{}1.5)%, and the Cabibbo-suppressed \ensuremath{\tau} decay mode B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${K}^{\mathrm{\ensuremath{-}}}$+neutral particles)=(1.6\ifmmode\pm\else\textpm\fi{}0.4)%. By looking for associated photons, we find B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${K}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{0}$+neutral particles) to be (1.2\ifmmode\pm\else\textpm\fi{}0.6)%. Using the channel K${\mathrm{*}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{K}}_{\mathit{S}}^{\mathit{O}}$${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, we find B(${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${K}^{\mathrm{*}\mathrm{\ensuremath{-}}}$(892)+neutral particles)=(1.4\ifmmode\pm\else\textpm\fi{}0.9)%. The quoted errors are the combined statistical and systematic errors.

We set an upper limit on the branching fraction B(τ−→ντK−K0)<0.26% at the 95% confidence level. The data sample was obtained with the TPC/Two-Gamma detector facility at the SLAC e+e− storage ring PEP. The process τ−→ντK−K0 is related via SU(3) to the second-class-current decay τ−→ντπ−η. Our limit is nearly 20 times smaller than the recently reported branching fraction B(τ−→ντπ−η) of (5.1±1.0±1.2)%, whereas SU(3) symmetry predicts the ratio of πη to KK¯ production to be at most 5:1. We also measure the branching fraction B(τ−→ντK*−)=(1.5±0.4*0.4%.Received 16 April 1987DOI:https://doi.org/10.1103/PhysRevLett.59.751©1987 American Physical Society

We report on a search for the pair production of leptoquarks and colored leptons in e+e− annihilations t center-of-mass energies from 50 to 60.8 GeV, using the AMY detector at TRISTAN. No evidence for such particles is found and 95% CL mass limits are given.

The NA14 photoproduction experiment, carried out at the CERN SPS, has measured the inclusive cross section of events with a prompt photon at high pT in the final state. Here we present a study of the topology of the final state of these events. The topology differs from that observed for events with an identified π0 in the same kinematical domain. Using these differences we have extracted the contribution from the Born term to the inclusive prompt photon cross section. The result is in good agreement with theoretical predictions and supports the assignment of a fractional electric charge to the quarks.

Two CMS production Cathode Strip Chambers were tested for aging effects in a high-radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1 m2 or 700 m of wire in each chamber. The 40% Ar+50% CO2+10% CF4 gas mixture was provided by an open-loop gas system for one of the chambers and by a closed-loop re-circulating gas system for the other. After an accumulation of 0.3–0.4 C/cm of a wire, equivalent to about 30–50 years of operation at peak LHC luminosity, no significant changes in gas gain, chamber efficiency and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from ∼2 to ∼10 nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 to 10–100 GΩ. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.

This note summarizes the results of a study of the identification of the H0→W+W-→ℓ+ℓ'-νℓℓ' signal for MH0 = 170 GeV c-2. This study is motivated by the papers written by Dittmar and Dreiner. We carried out a similar study using Pythia to generate events and a CMSIM calorimeter simulation for the jet veto, and compared with their results. We also show some comparison between Pythia- and ISAJET-generated events for this process.

We report results of a study of four-lepton final states produced in e+e− collisions at center-of-mass energies from 50 to 61.4 GeV using the AMY detector at the TRISTAN collider. For the cases where two or three charged tracks are produced at large angles relative to the beam direction, the cross sections agree with QED. However, we observe an excess of e+e−→e+e−μ+μ− events with four tracks at wide angles and with dimuon mass less than 1.0 GeV/c2.

A search for pair production of fourth-generation sequential leptons in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at a center-of-mass energy $\sqrt{s}=56$ GeV is reported. Event topologies corresponding to the cases where one particle decays leptonically while the other decays hadronically as well as those where both particles decay hadronically were explored. We set a 95%-confidence-level lower limit of 27.6 GeV/${\mathit{c}}^{2}$ for the mass of a fourth-generation lepton.

A search for unstable heavy neutral leptons has been made at center-of-mass energies from 50 to 60.8 GeV with the AMY detector at the KEK Storage ring TRISTAN. The neutral leptons are assumed to decay via mixing to electrons and muons. Events with two leptons were searched for. No evidence for their existence was found. Limits in the mass range \ensuremath{\le}28.1 GeV/${c}^{2}$ and mixing-parameter range 9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$\ensuremath{\le}\ensuremath{\Vert}${U}_{\mathrm{lL}}$${\ensuremath{\Vert}}^{2}$\ensuremath{\le}1 are presented for Dirac- and Majorana-type neutrinos.

A quantitative test of QCD from high energy photoproduction of large transverse momentum charged hadrons, using incident γ energies between 50 and 150 GeV, is presented. The inclusive hadron P1 and Pt distributions show a clear excess over the VDM contribution. This excess is found to be in good agreement with second-order QCD calculations. This agreement does not depend critically on the choice of the gluon fragmentation function, and is observed over the large kinematical domain covered by this experiment.

We describe an improved version of COPS, a CCD based Optical Position Sensor, which can measure or monitor positions of attached elements with accuracies better than 0.05 mm at distances of tens of meters. The main application of this device is in the precision alignment and monitoring of radiation detectors in experimental high-energy physics. The improved sensor, named NUCOPS, has a set of four linear CCD arrays attached to the inside walls of a rigid square tube, and can be illuminated by a cross-hair laser coming from either direction. Like the old device, a NUCOPS can measure changes in its position to the laser lines with reproducibility better than 2 μm. It has been designed specifically for use in the alignment system of the Endcap Muon detectors for the CMS experiment at LHC.

With the growth in size and complexity of High Energy Physics experiments, and the accompanying increase in the number of collaborators spread across the globe, the importance of widely relaying timely monitoring and status information has grown. To this end, we present online Web Based Monitoring solutions from the CMS experiment at CERN. The web tools developed present data to the user from many underlying heterogeneous sources, from real time messaging systems to relational databases. We provide the power to combine and correlate data in both graphical and tabular formats of interest to the experimentalist, with data such as beam conditions, luminosity, trigger rates, detector conditions and many others, allowing for flexibility on the user side. We also present some examples of how this system has been used during CMS commissioning and early beam collision running at the Large Hadron Collider.

The compact muon solenoid (CMS) experiment is a general-purpose detector for high-energy collision at the large hadron collider (LHC) at CERN. It employs an online data quality monitoring (DQM) system to promptly spot and diagnose particle data acquisition problems to avoid data quality loss. In this study, we present semi-supervised spatio-temporal anomaly detection (AD) monitoring for the physics particle reading channels of the hadronic calorimeter (HCAL) of the CMS using three-dimensional digi-occupancy map data of the DQM. We propose the GraphSTAD system, which employs convolutional and graph neural networks to learn local spatial characteristics induced by particles traversing the detector, and global behavior owing to shared backend circuit connections and housing boxes of the channels, respectively. Recurrent neural networks capture the temporal evolution of the extracted spatial features. We have validated the accuracy of the proposed AD system in capturing diverse channel fault types using the LHC Run-2 collision data sets. The GraphSTAD system has achieved production-level accuracy and is being integrated into the CMS core production system--for real-time monitoring of the HCAL. We have also provided a quantitative performance comparison with alternative benchmark models to demonstrate the promising leverage of the presented system.

The Compact Muon Solenoid (CMS) experiment is a general-purpose detector for high-energy collision at the Large Hadron Collider (LHC) at CERN. It employs an online data quality monitoring (DQM) system to promptly spot and diagnose particle data acquisition problems to avoid data quality loss. In this study, we present a semi-supervised spatio-temporal anomaly detection (AD) monitoring system for the physics particle reading channels of the Hadron Calorimeter (HCAL) of the CMS using three-dimensional digi-occupancy map data of the DQM. We propose the GraphSTAD system, which employs convolutional and graph neural networks to learn local spatial characteristics induced by particles traversing the detector and the global behavior owing to shared backend circuit connections and housing boxes of the channels, respectively. Recurrent neural networks capture the temporal evolution of the extracted spatial features. We validate the accuracy of the proposed AD system in capturing diverse channel fault types using the LHC collision data sets. The GraphSTAD system achieves production-level accuracy and is being integrated into the CMS core production system for real-time monitoring of the HCAL. We provide a quantitative performance comparison with alternative benchmark models to demonstrate the promising leverage of the presented system.

The Compact Muon Solenoid is a large a complex general purpose experiment at the CERN Large Hadron Collider (LHC), built and maintained by many collaborators from around the world. Efficient operation of the detector requires widespread and timely access to a broad range of monitoring and status information. To that end the Web Based Monitoring (WBM) system was developed to present data to users located anywhere from many underlying heterogeneous sources, from real time messaging systems to relational databases. This system provides the power to combine and correlate data in both graphical and tabular formats of interest to the experimenters, including data such as beam conditions, luminosity, trigger rates, detector conditions, and many others, allowing for flexibility on the user's side. This paper describes the WBM system architecture and describes how the system has been used from the beginning of data taking until now (Run1 and Run 2).

This document is intended as a guide for getting started with the Z' generation with PYTHIA[1]. Several different conventions used in literature are discussed, and the conversion among these is given. The Z' couplings to fermions are given for the sequential Z', the Z' model-lines of Ref. [2], and the popular E6 Z' models.

The CMS experiment is about to embark on its first physics run at the LHC. To maximize the effectiveness of physicists and technical experts at CERN and worldwide and to facilitate their communications, CMS has established several dedicated and inter-connected operations and monitoring centres. These include a traditional 'Control Room' at the CMS site in France, a 'CMS Centre' for up to fifty people on the CERN main site in Switzerland, and remote operations centres, such as the 'LHC@FNAL' centre at Fermilab. We describe how this system of centres coherently supports the following activities: (1) CMS data quality monitoring, prompt sub-detector calibrations, and time-critical data analysis of express-line and calibration streams; and (2) operation of the CMS computing systems for processing, storage and distribution of real CMS data and simulated data, both at CERN and at offsite centres. We describe the physical infrastructure that has been established, the computing and software systems, the operations model, and the communications systems that are necessary to make such a distributed system coherent and effective.

The possibility of realizing linear magnetic recording systems over 15 Gb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> recording density has been shown in our test with newly developed metal particulate (MP) tape using 35-nm-size fine metal particles and a GMR head designed for hard disk drive (HDD). It was done under a read-track-base calculation with the following media: magnetic layer thickness =60 nm, surface roughness <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ra</i> =2.0 nm.

Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16mm) for the cathode-to-anode wire distance of 5mm, the six-plane structure of these chambers yields a spatial resolution of about 80μm, essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300ns) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is ∼4ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25ns. Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large-scale chambers; 700m of wire were irradiated for a dose up to 0.4C/cm of the total accumulated charge.

The foundation of the CDF Run II online event monitoring framework was implemented well before the start of the physics runs, allowing development of a coherent monitoring software across all the subsystems, consequently making maintenance and operation simple and efficient. Only one shift person is needed to monitor the entire CDF detector, including the trigger system. High data quality is assured in real time and well defined monitoring results are propagated coherently to offline data sets used for physics analysis. We describe the CDF Run II online event monitoring system and operation, including the remote monitoring shift operation started in November 2006.

The rate of performance improvements of the LHC at CERN has had a strong influence on the characteristics of the monitoring tools developed for the experiments. We present some of the latest additions to the suite of Web Based Monitoring services for the CMS experiment, and explore the aspects that address the roughly 20-fold increase in peak instantaneous luminosity over the course of 2011. One of these user-friendly tools allows collaborators to easily view, and make correlations among, accelerator configuration information such as bunch patterns, measured quantities such as intensities, vacuum pressures, and background conditions, as well as derived quantities such as luminosity and the number of simultaneous interactions per beam crossing. An additional tool summarizes the daily, weekly, and yearly luminosity and efficiency. Finally, we discuss a trigger cross section and rate fitting service that uses data from previous runs to validate current running conditions, as well as to serve as a predictive extrapolation tool for developing triggers for higher luminosity running.

We compare the pT dependence of pion, kaon and proton production cross sections in the central rapidity region in e+e− annihilation events and in proton-proton collisions at ISR energies. We find similarities both in the pT dependence of cross sections and in the particle composition as a function of pT, in agreement with the hypothesis of a universal mechanism of particle production.

We report on the first search with virtual photon-photon collisions for narrow, neutral resonances with even C parity in the mass range 4.5&lt;W&lt;19 GeV. The data were obtained via the process ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\gamma}}^{\mathrm{*}}$${\ensuremath{\gamma}}^{\mathrm{*}}$\ensuremath{\rightarrow}e $^{+}e^{\mathrm{\ensuremath{-}}}$R with both the scattered ${e}^{+}$ and ${e}^{\mathrm{\ensuremath{-}}}$ detected. We find upper limits (95% confidence level) for the partial decay width of a resonance into two photons, ranging from 50 keV at W=4.5 GeV to 10 MeV at W=19 GeV. These limits constrain theoretical models involving neutral composite bosons.

Searches for the pair production of the supersymmetric partner particles of leptons, quarks, and non-minimal Higgs have been made in e +e − annihilations at center-of-mass energies between 50 and 60.8 GeV using the AMY detector at TRISTAN. No evidence for their existence is observed and 95% CL mass limits are presented.

We describe the online monitoring system of the CDF II experiment designed to check the data quality of all subsystems in real-time.A subset of the events accepted by the highest trigger level is made available to 10 analysis programs which check the data quality on an event-by-event basis and produce diagnostic histograms.The monitoring results are distributed to the user via a client-server scheme.The display clients feature an intuitive GUI which allows to browse and request the available results.The monitoring package is coded in C++ and makes use of the ROOT analysis framework which offers histogramming methods, networking classes and graphics handling.We report about the design and the implementation of the monitoring system and discuss our experiences during the first months of operation.

We describe the online event monitoring systems using ROOT for the CDF and DO collaborations in the upcoming Fermilab Tevatron runII. The CDF and DO experiments consist of many detector subsystems and will run in a high rate large bandwidth data transfer environment. In the experiments, it is crucial to monitor the performance of each subsystem and the integrity of the data, in real time with minimal interruption. ROOT is used as the main analysis tool for the monitoring systems and its GUI is used to browse the results via socket, allowing multiple GUI client connections.

The Compact Muon Solenoid (CMS) is a large and complex general purpose experiment at the CERN Large Hadron Collider (LHC), built and maintained by many collaborators from around the world. Efficient operation of the detector requires widespread and timely access to a broad range of monitoring and status information. To this end the Web Based Monitoring (WBM) system was developed to present data to users located anywhere from many underlying heterogeneous sources, from real time messaging systems to relational databases. This system provides the power to combine and correlate data in both graphical and tabular formats of interest to the experimenters, including data such as beam conditions, luminosity, trigger rates, detector conditions, and many others, allowing for flexibility on the user side. This paper describes the WBM system architecture and describes how the system was used during the first major data taking run of the LHC.

The Compact Muon Solenoid (CMS) is a large and complex general purpose experiment at the CERN Large Hadron Collider (LHC), built and maintained by many collaborators from around the world. Efficient operation of the detector requires widespread and timely access to a broad range of monitoring and status information. To this end the Web Based Monitoring (WBM) system was developed to present data to users located anywhere from many underlying heterogeneous sources, from real time messaging systems to relational databases. This system provides the power to combine and correlate data in both graphical and tabular formats of interest to the experimenters, including data such as beam conditions, luminosity, trigger rates, detector conditions, and many others, allowing for flexibility on the user side. This paper describes the WBM system architecture and describes how the system was used during the first major data taking run of the LHC.

High Energy Physics has a long history of coping with cutting-edge data rates in its efforts to extract meaning from experimental data. The quantity of data from planned future experiments that must be analyzed practically in real-time to enable efficient filtering and storage of the scientifically interesting data has driven the development of sophisticated techniques which leverage technologies such as MPI, OpenMP and Intel TBB. We show the evolution of data collection, triggering and filtering from the 1990s with TeVatron experiments into the future of Intensity Frontier and Cosmic Frontier experiments and show how the requirements of upcoming experiments lead us to the development of high-performance streaming triggerless DAQ systems.

For large international High Energy Physics experiments, modern web technologies make the online monitoring of detector status, data acquisition status, trigger rates, luminosity, etc., accessible for the collaborators anywhere and anytime.This helps the collaborating experts monitor the status of the experiment, identify the problems and improve data taking efficiency.We present the online Web-Based Monitoring project of the CMS experiment at the LHC at CERN.The data sources are relational databases and various messaging systems.The project provides a vast amount of in-depth information including real-time data, historical trends and correlations in a user-friendly way.

Consumer Server is a program to handle event data and consumer trigger requests I/Os among Level 3 farm and consumer processes in CDF new data acquisition system. This program uses standard UNIX libraries and commercial network technologies to obtain higher portability. The authors describe the concept and configuration of the Consumer Server and report its performance.

We describe the online event monitoring systems using ROOT for the CDF and DO collaborations in the upcoming Fermilab Tevatron run II. The CDF and DO experiments consist of many detector subsystems and will run in a high rate large bandwidth data transfer environment. In the experiments, it is crucial to monitor the performance of each subsystem and the integrity of the data, in real time with minimal interruption. ROOT is used as the main analysis tool for the monitoring systems and its GUI is used to browse the results via socket, allowing multiple GUI client connections.

With the growth in size and complexity of High Energy Physics experiments, and the accompanying increase in the number of collaborators spread across the globe, the importance of widely relaying timely monitoring and status information has grown. To this end, we present online Web Based Monitoring solutions from the CMS experiment at CERN. The web tools developed present data to the user from many underlying heterogeneous sources, from real time messaging system to relational databases. We provide the power to combine and correlate data in both graphical and tabular formats of interest to the experimentalist, with data such as beam conditions, luminosity, trigger rates, detector conditions and many others, allowing for flexibility on the user side. We also present some examples of how this system has been used during CMS commissioning and early beam collision running at the Large Hadron Collider.

The foundation of the CDF Run II online event monitoring framework, placed well before the physics runs start, allowed to develop coherent monitoring software across all the different subsystems which consequently made maintenance and operation simple and efficient. Only one shift person is needed to monitor the entire CDF detector, including the trigger system. High data quality check is assured in real time and well defined monitoring results are propagated coherently to offline datasets used for physics analyzes. We describe the CDF Run II online event monitoring system and operation, with emphasis on the remote monitoring shift operation started since November 2006 with Pisa-INFN as pilot Institution and exploiting the WEB based access to the data.

Results of a search for the pair production of charged heavy leptons in e + e − annihilations over the center-of-mass energy range of 50 to 60.8 GeV are reported. We assume that the leptons are of the sequential type but have allowed for the case where the associated neutrino might be massive. Separate searches for evidence for decays to hadronic and leptonic final states, searches specialized for the case where the charged lepton and its associated neutrino are close in mass, and a search for stable heavy leptons have uncovered no evidence for the production of such particles at these energies. Mass limits for heavy leptons and their associated neutrinos are determined for a range of hadronic and leptonic decay branching fractions. A sequential charged heavy lepton with mass between 12.6 and 29.6 GeV/c 2 and with massless neutrino is excluded at the 95% confidence level.

In this paper we present a description of a three-view segmented hadron calorimeter which provides three dimensional information on shower location as well as the usual energy deposition. We summarize several important results emerging from the use of our hadron calorimeter both as a component of an hybrid bubble chamber trigger and in the data reduction and analysis. Calibration data taken during our run cycle allowed determination of the spatial and energy resolution of the calorimeter as a function of the shower distribution and incident particle energy. Also an algorithm was developed which permitted good determination of the shower trajectory and errors even for showers not fully contained within the calorimeter and thereby indicating a significant loss of energy deposition.

A search for the pair production of charged Higgs particles decaying via the H−→τν¯ mode has been made in e+e− annihilations at center-of-mass energies between 50 and 60.8 GeV using the AMY detector at the KEK collider TRISTAN. No evidence for their existence is observed and 95%-C.L. mass limits are presented. The result has been interpreted in terms of the tanβ parameter in the Higgs sector.Received 27 February 1990DOI:https://doi.org/10.1103/PhysRevD.42.949©1990 American Physical Society

A facility, LHC@FNAL, is being constructed at Fermi- lab to help people contribute remotely to the Large Had- ron Collider (LHC) effort at CERN. As a facility, LHC@FNAL has three primary functions: 1. To provide access to information in a manner that is similar to what is available in control rooms at CERN, and to enable members of the LHC community to par- ticipate remotely in LHC and CMS (1) activities. 2. To serve as a communications conduit between CERN and members of the LHC community located in North America. 3. To allow visitors to Fermilab to see firsthand how re- search is progressing at the LHC. Visitors will be able to see current LHC activities, and to see how future international projects in particle physics can benefit from active participation from remote locations.

Presented are the main design features and performance results of the cathode strip chambers (CSCs) for the CMS Endcap Muon System. The six-plane structure of these chambers yields a spatial resolution of about 80 /spl mu/m, essentially uniform and independent of the strip width (up to 16 mm, which is unusually wide for the cathode-to-anode wire distance of 5 mm). In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300ns) is obtained using a simple network of comparators. The time resolution achieved at the trigger level is /spl sim/4ns (RMS) that allows unambiguous tagging of bunch crossing occurring every 25 ns. Aging tests, including those obtained with a recirculating gas system, showed only minor aging effects. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C/cm of the total accumulated charge.

In this article we discuss two topics. Both are part of the CDF Run II-online system. First we present the design and current status of the CDF online monitoring project which is based on ROOT. The framework consists of three parts, the online event analysis programs to check the detector and data, the browser to display their results, and the server program which communicates with the display via socket connections. The second topic is an ORACLE based database application. It keeps track of the exact location, repair history, modification history and status of all DAQ electronic equipment during development, commissioning and physics running periods. We discuss the implementation and status of the database.

In this article we discuss two topics. Both are part of the CDF Run II-online system. First we present the design and current status of the CDF online monitoring project which is based on ROOT. The framework consists of three parts, the online event analysis programs to check the detector and data, the browser to display their results, and the server program which communicates with the display via socket connections. The second topic is an ORACLE based database application. It keeps track of the exact location, repair history, modification history and status of all DAQ electronic equipment during development, commissioning and physics running periods. We discuss the implementation and status of the database.

We present the results of a search for third generation leptoquark (LQ) pairs in 110{plus_minus}8pb{sup -1} of {bar p}p collisions at {radical}(s)=1.8TeV recorded by the Collider Detector at Fermilab. We assume third generation leptoquarks decay to a {tau} lepton and a b quark with branching ratio {beta}. We observe one candidate event, consistent with standard model background expectations. We place upper limits on {sigma}({bar p} p{r_arrow}LQ{ovr LQ}){center_dot}{beta}{sup 2} as a function of the leptoquark mass M{sub LQ}. We exclude at 95{percent} confidence level scalar leptoquarks with M{sub LQ}{lt}99GeV/c{sup 2}, gauge vector leptoquarks with M{sub LQ}{lt}225GeV/c{sup 2}, and nongauge vector leptoquarks with M{sub LQ}{lt}170GeV/c{sup 2} for {beta}=1. {copyright} {ital 1997} {ital The American Physical Society}

We have observed bottom-charm mesons via the decay mode B{sup {plus_minus}}{sub c}{r_arrow}J/{psi}thinsp {ell}{sup {plus_minus}}{nu} in 1.8thinspthinspTeV p{ovr p} collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/{psi}thinsp{ell} mass distribution yielded 20.4{sup +6.2}{sub {minus}5.5} events from B{sub c} mesons. A fit to the same distribution with background alone was rejected at the level of 4.8thinspthinspstandard deviations. We measured the B{sup +}{sub c} mass to be 6.40{plus_minus}0.39(stat){plus_minus}0.13( syst) GeV/c{sup 2} and the B{sup +}{sub c} lifetime to be 0.46{sup +0.18}{sub {minus}0.16}(stat) {plus_minus}0.03(syst)thinspps . Our measured yield (production cross section times branching ratio) for B{sup +}{sub c}{r_arrow}J/{psi}thinsp{ell}{sup +}{nu} relative to that for B{sup +}{r_arrow}J/{psi}thinspK{sup +} is 0.132{sup +0.041}{sub {minus}0.037}(stat ){plus_minus}0.031(syst){sup +0.032}{sub {minus}0.020}(lifetime) . {copyright} {ital 1998} {ital The American Physical Society }

We have searched for anomalous production of missing E{sub T}thinsp(E/ {sub T}) , jets, leptons (e,thinsp{mu},thinsp{tau}) , b quarks , or additional photons in events containing two isolated, central ({vert_bar}{eta}{vert_bar}{lt}1.0) photons with E{sub T}{gt}12 GeV . The results are consistent with standard model expectations, with the possible exception of one event that has in addition to the two photons a central electron, a high-E{sub T} electromagnetic cluster, and large E/{sub T} . We set limits using two specific supersymmetry scenarios for production of diphoton events with E/{sub T} . {copyright} {ital 1998} {ital The American Physical Society}

We present a measurement of the B{sup 0}{leftrightarrow}{bar B}{sup 0} oscillation frequency using a flavor tagging method based on correlations of B meson flavor with the charge of other particles produced in p{bar p} collisions at {radical}(s)=1.8 TeV. Such correlations are expected to arise from b quark hadronization and from B{sup {asterisk}{asterisk}} decays. We partially reconstruct B mesons using the semileptonic decays B{sup 0}{r_arrow}l{sup +}D{sup ({asterisk}){minus}} X and B{sup +}{r_arrow}l{sup +}{bar D}{sup 0}X. From the oscillation frequency, we obtain the mass difference between the two B{sup 0} mass eigenstates, {Delta}m{sub d}=0.471{sup +0.078}{sub {minus}0.068} (stat){plus_minus}0.034(syst ){h_bar} ps{sup {minus}1}, and measure the efficiency and purity of this flavor tagging method for both charged and neutral B mesons. {copyright} {ital 1998} {ital The American Physical Society}

We observe hadronic W decays in t{bar t}{r_arrow}W({r_arrow} {ell}{nu})+{ge}4 jet events using a 109 pb{sup {minus}1} data sample of p{ovr p} collisions at {radical}(s)=1.8 TeV collected with the Collider Detector at Fermilab. A peak in the dijet invariant mass distribution is obtained that is consistent with W decay and inconsistent with the background prediction by 3.3{sigma} . From this peak we measure the W mass to be 77.2{plus_minus}4.6(stat+syst) GeV/c{sup 2} . This result demonstrates the presence of a second W boson in t{bar t} candidates in the W({r_arrow}{ell}{nu})+{ge}4 jet channel. {copyright} {ital 1998} {ital The American Physical Society}

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Takanobu Handa, Kaori Maeshima, Juan Valls, Rocio Vilar, CDF collaboration; Search for technicolor particles in W+2jet with b-tag channel at CDF. AIP Conf. Proc. 10 August 1998; 435 (1): 766–771. https://doi.org/10.1063/1.56261 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

We present the first observation of the all hadronic decay of t{ovr t} pairs. The analysis is performed using 109 pb{sup {minus}1} of p{ovr p} collisions at {radical}(s)=1.8 TeV collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two b jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be 186{plus_minus}10{plus_minus}12 GeV/c{sup 2 } . {copyright} {ital 1997} {ital The American Physical Society}

We have used 87 pb{sup {minus}1} of data collected with the collider detector at Fermilab to search for new particles decaying to b{ovr b} . We present model-independent upper limits on the cross section for narrow resonances which exclude the color-octet technirho in the mass interval 350{lt}M{lt}440 GeV/c{sup 2} . In addition, we exclude top-gluons, predicted in models of top-color-assisted technicolor, of width {Gamma}=0.3M in the mass range 280{lt}M{lt}670 GeV/c{sup 2} , of width {Gamma}=0.5M in the mass range 340{lt}M{lt}640 GeV/c{sup 2} , and of width {Gamma}=0.7M in the mass range 375{lt}M{lt}560 GeV/c{sup 2} . {copyright} {ital 1999} {ital The American Physical Society}

A new technique to measure the ratio of [ital b] quark fragmentation fractions in p[bar p] collisions is described. Using a 70-pb[sup [minus]1] sample of low-mass dimuon trigger data recorded with the Collider Detector at Fermilab, we identify [ital B] mesons by observing the double semileptonic decays b[r arrow]c[mu]X with c[r arrow]s[mu]X. By counting the numbers of K[sup [asterisk]](892)[sup 0], K[sup [asterisk]](892)[sup +], and [phi](1020) mesons produced in association with these muon pairs, we measure the ratio of strange to nonstrange [ital B] meson production to be f[sub s]/(f[sub u]+f[sub d])=[21.0[plus minus]3.6(stat)[sub [minus]3.0][sup +3.8](syst)][percent]. This measurement is the most precise available from hadron collisions to date. Limits on the branching fractions of semileptonic charm meson decays with K[sub 1](1270), K[sub 1][sup [asterisk]](1410), and K[sub 2][sup [asterisk]](1430) mesons in the final state are also obtained. [copyright] [ital 1999] [ital The American Physical Society]

We report a measurement of the fraction of dijet events with a rapidity gap between jets produced by color-singlet exchange in {ovr p}p collisions at {radical} (s) =630 GeV at the Fermilab Tevatron. In events with two jets of transverse energy E{sup jet}{sub T}{gt}8 GeV , pseudorapidity in the range 1.8{lt}{vert_bar}{eta}{sup jet}{vert_bar}{lt}3.5 and {eta}{sub 1}{eta}{sub 2}{lt}0 , the color-singlet exchange fraction is found to be R=[2.7{plus_minus}0.7(stat){plus_minus}0 .6(syst)]{percent} . Comparisons are made with results obtained at {radical} (s) =1800 GeV and with theoretical expectations. {copyright} {ital 1998} {ital The American Physical Society }

We present a measurement of the differential cross section d{sigma}/d{summation}E{sup jet}{sub T} for the production of multijet events in p{ovr p} collisions where the sum is over all jets with transverse energy E{sup jet}{sub T}{gt}E{sup min}{sub T} . The measured cross section for events with {summation}E{sup jet}{sub T}{gt} 320 GeV is compared to O({alpha}{sup 3}{sub s}) perturbative QCD predictions and QCD parton shower Monte Carlo predictions. The agreement between the O({alpha}{sup 3}{sub s}) predicted and observed event rates is reasonable for E{sup min}{sub T}=100 GeV , but poorer for E{sup min}{sub T}=20 GeV . {copyright} {ital 1998} {ital The American Physical Society}

We search for new long-lived particles which decay to Z{sup 0} bosons by looking for Z{sup 0}{r_arrow}e{sup +}e{sup {minus}} decays with displaced vertices. We find no evidence for parent particles of the Z{sup 0} with long lifetimes in 90thinsppb{sup {minus}1} of data from the CDF experiment at Fermilab. We set a cross section limit as a function of the lifetime of the parent particle for both a generic Z{sup 0} parent and a fourth-generation, charge {minus} (1) /(3) quark that decays into Z{sup 0}b. {copyright} {ital 1998} {ital The American Physical Society}

A search for B{sup 0}{sub s}-{ovr B}{sup 0}{sub s} oscillations is performed in a sample of B{sup 0}{sub s} semileptonic decays collected using dilepton triggers at the Tevatron Collider during 1992{endash}1995. The B{sup 0}{sub s} is reconstructed using {phi} meson-lepton correlations; its initial production flavor is determined with the second lepton in the event. From a signal of 1068 with a B{sup 0}{sub s} purity of 61{percent} , we obtain a limit on the B{sup 0}{sub s}-{ovr B}{sup 0}{sub s} oscillation frequency of {Delta}m{sub s}{gt}5.8 ps{sup {minus}1} at 95{percent} confidence level. {copyright} {ital 1999} {ital The American Physical Society}

We present a study of J/{psi} and {psi}(2S) production in p{bar p} collisions, at {radical}(s)=1.8 TeV with the CDF detector at Fermilab. The J/{psi} and {psi}(2S) mesons are reconstructed using their {mu}{sup +}{mu}{sup {minus}} decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, {vert_bar}{eta}{vert_bar}{lt}0.6 . We also measure the fraction of these events originating from b hadrons. We thus extract individual cross sections for J/{psi} and {psi}(2S) mesons from b -quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct {psi}(2S) production compared with predictions from the color singlet model. {copyright} {ital 1997} {ital The American Physical Society}

A strong signal for double parton (DP) scattering is observed in a 16pb{sup {minus}1} sample of {bar p}p{r_arrow}{gamma}/{pi}{sup 0}+3jets+X data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single {bar p}p collision. We isolate a large sample of data ({approximately}14000 events) of which 53{percent} are found to be DP. The process-independent parameter of double parton scattering, {sigma}{sub eff}, is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate {bar p}p collisions. The result {sigma}{sub eff}=(14.5{plus_minus}1.7{sub {minus}2.3}{sup +1.7})mb represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman x dependence of {sigma}{sub eff} is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events. {copyright} {ital 1997} {ital The American Physical Society}

We report the observations of the decays B{sup +}{r_arrow}{psi}(2S)K{sup +} and B{sup 0}{r_arrow}{psi}(2S)K{sup {asterisk}}(892){sup 0} in p{bar p} collisions at a center-of-mass energy of 1.8 TeV using a 110thinsppb{sup {minus}1} data sample recorded by the Collider Detector at Fermilab. We also reconstruct the decays B{sup +}{r_arrow}J/{psi}K{sup +} and B{sup 0}{r_arrow}J/{psi}K{sup {asterisk}}(892){sup 0} and measure the six ratios of branching fractions of these four decays. The relative branching-fraction results are shown to be consistent with phenomenological factorization calculations of hadronic B-meson decays. We use the world-average branching fraction B(B{sup +}{r_arrow}J/{psi}K{sup +}) to derive B{bold (}B{sup +}{r_arrow}{psi}(2S)K{sup +}{bold )}=(0.56{plus_minus}0.08{plus_minus}0.10){times}10{sup {minus}3}, B{bold (}B{sup 0}{r_arrow}{psi}(2S)K{sup {asterisk}}(892){sup 0}{bold )}=(0.92{plus_minus}0.20{plus_minus}0.16){times}10{sup {minus}3}, and B{bold (}B{sup 0}{r_arrow}J/{psi}K{sup {asterisk}}(892){sup 0}{bold )}=(1.78{plus_minus}0.14{plus_minus}0.29){times}10{sup {minus}3}, where the first and second uncertainties are statistical and systematic, respectively. {copyright} {ital 1998} {ital The American Physical Society}