J. Konigsberg

We describe the initial performance of the detector used for the luminosity measurement in the CDF experiment in Run II at the Tevatron. The detector consists of low-mass gaseous Cherenkov counters with high light yield (∼100 photoelectrons) and monitors the process of inelastic pp̄ scattering. It allows for several methods of precise luminosity measurements at peak instantaneous luminosities of 2×1032cm−2s−1, corresponding to an average of six pp̄ interactions per bunch crossing.

▪ Abstract We survey top-quark physics from what has been learned so far at the Tevatron to the searches planned at present and future colliders. We summarize the richness of the measurements and discuss their possible impact on our understanding of the standard model by pointing out their key elements and limitations. We discuss how the top quark may provide a connection to new or unexpected physics. The literature on many of the topics we address is sizeable. We attempt to consolidate the most salient points into a complete, coherent overview.

We have built a novel device for precision measurements of luminosity in the CDF experiment at the high pp̄ collision rates expected during Run II. The detector consists of long, conical, gaseous Cherenkov counters that point to the collision region and monitor the average number of inelastic pp̄ interactions by measuring the number of particles, and their arrival time, in each bunch crossing. For these primary particles, using isobutane at atmospheric pressure as a radiator, a large amount of Cherenkov light (∼100 photoelectrons) will be collected, with good amplitude and time resolutions, onto small and efficient PMTs. Suitable amplitude thresholds will be applied to discriminate from non-primary particles and other backgrounds which yield little light in the counters. This detector is expected to reliably perform bunch-by-bunch luminosity measurements at peak instantaneous luminosities of 2×1032 cm−2 s−1 with six interactions per bunch crossing, on average, and respond to a 132 ns bunch spacing.

A search for the decay ${\mathit{K}}_{\mathit{L}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{\ifmmode\pm\else\textpm\fi{}}$${\mathit{e}}^{\ensuremath{\mp}}$ with significantly increased experimental sensitivity has yielded no events. The 90% confidence level limit on the branching ratio is B(${\mathit{K}}_{\mathit{L}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{\ifmmode\pm\else\textpm\fi{}}$${\mathit{e}}^{\ensuremath{\mp}}$)3.9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$. When this data set is combined with earlier data the upper limit is 3.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$.

A Time-of-Flight (TOF) detector, based on plastic scintillators and fine-mesh photomultipliers, has been added to the Collider Detector at Fermilab (CDF)-II experiment at the Tevatron pp̄ collider. The primary physics motivation is to provide charged kaon identification to improve neutral B meson flavor determination. Besides that, the TOF detector found application in the CDF trigger system in implementation of highly ionizing particle, high multiplicity and cosmic rays triggers.

The W\ensuremath{'} is a charged, heavy, vector boson predicted to exist by some extensions of the standard model. We have searched for the processes W\ensuremath{'}\ensuremath{\rightarrow}e\ensuremath{\nu} and W\ensuremath{'}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\nu} for ${\mathrm{M}}_{\mathrm{W}\ensuremath{'}}$>100 GeV/${\mathrm{c}}^{2}$, in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at s=1.8 TeV, using data taken with the Collider Detector at Fermilab. The nonobservation of these processes leads to a lower limit of 520 GeV/${\mathrm{c}}^{2}$ (95% confidence level) on the mass of the W\ensuremath{'}, assuming standard-strength couplings to three fermion generations.

Concurrent with our search for the decays ${K}_{L}^{0}$\ensuremath{\rightarrow}\ensuremath{\mu}e and ${K}_{L}^{0}$\ensuremath{\rightarrow}ee, we have observed 87 ${K}_{L}^{0}$\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\mu} events. Normalizing this sample to the simultaneous observation of the decay ${K}_{L}^{0}$\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, we obtain the branching ratio B(${K}_{L}^{0}$\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\mu}) =[5.8\ifmmode\pm\else\textpm\fi{}0.6(stat)\ifmmode\pm\else\textpm\fi{}0.4 (syst)] \ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}9}$.

A search for the decays ${K}_{L}^{0}$\ensuremath{\rightarrow}\ensuremath{\mu}e and ${K}_{L}^{0}$\ensuremath{\rightarrow}ee has produced no examples of either process. When normalized to the decay ${K}_{L}^{0}$\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, the 90%-C.L. upper limits on the branching ratios are B(${K}_{L}^{0}$\ensuremath{\rightarrow}\ensuremath{\mu}e)2.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ and B(${K}_{L}^{0}$\ensuremath{\rightarrow}ee)3.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$. .AE

We have measured the branching ratio for K0L→μ+μ− using our full data set obtained during running periods in 1988, 1989, and 1990. The total number of μ+μ− candidates after a background subtraction is 707, which represents the largest sample to date of this rare decay mode. Our result is B(K0L→μ+μ−)=(6.86±0.37)×10−9, which is consistent with earlier results and very near the unitarity bound. The upper limit on B(K0L→μ+μ−) is used to set an upper limit on the real part of the amplitude scrA(K0L→μ+μ−); this is subsequently used to constrain the top quark mass mt and the Wolfenstein parameter ρ of the CKM matrix.Received 29 August 1994DOI:https://doi.org/10.1103/PhysRevD.51.985©1995 American Physical Society

We describe here a novel approach to luminosity measurements for pp̄ collider experiments. We propose to use low-pressure gaseous Cherenkov counters at small angles relative to the beam direction to determine the rate of inelastic pp̄ interactions. With a propotype counter, we measured at a beam test a light yield of over 100 photoelectrons and a timing resolution of better than 50 ps. The CDF collaboration will use a detector based on this technique for luminosity measurements at the upgraded Tevatron collider.

With a significant increase in experimental sensitivity, we have observed an additional 281 K0L→μμ events after a background subtraction of 19±6 events. Normalizing this sample to the simultaneous observation of the decay K0L→π+π−, we obtain the branching ratio B(K0L→μμ)=[7.6±0.5(stat)±0.4(syst)]×10−9. Combining these data with our previously published sample containing 87 events yields B(K0L→μμ)=(7.0±0.5)×10−9.Received 28 February 1991DOI:https://doi.org/10.1103/PhysRevD.44.R1©1991 American Physical Society

This article describes a new charged-particle track fitting algorithm designed for use in high-speed electronics applications such as hardware-based triggers in high-energy physics experiments. Following a novel technique designed for fast electronics, the positions of the hits on the detector are transformed before being passed to a linearized track parameter fit. This transformation results in fitted track parameters with a very linear dependence on the hit positions. The approach is demonstrated in a representative detector geometry based on the CMS detector at the Large Hadron Collider. The fit is implemented in FPGA chips and optimized for track fitting throughput and obtains excellent track parameter performance. Such an algorithm is potentially useful in any high-speed track-fitting application.

The performance of the CDF isolated endplug electron trigger in the 1993 run of the CDF experiment is presented. The trigger was designed to select events in pp interactions containing isolated electromagnetic clusters in the endplug calorimeter. The trigger was found to be 97% efficient for electrons from W decays in the range of rapidity covered by the trigger, and to provide a background rejection of a factor of 3. The neural network chip used to perform the isolation calculation exhibited no problems with reliability or stability during 8 months of running.

Abstract We have built, and used to take physics data, a digitizing and readout system for Brookhaven AGS Experiment 791, a high-rate search for rare kaon decays. All digitization of charge and time information is “flash” (performed in less than 200 ns), followed by front-end buffering and a pipelined readout with massive parallelism. A data transfer rate of 0.4 Gbyte/s into dual-port memories in eight 3081-emulating processors has been achieved. A readout-supervising circuit coordinates the three levels of event triggering and the movement of data throughout the system. The host Micro-VAX is interrupted only for the uploading of packets of fully filtered events from the 3081/E's. Digitizing and data transfer from the front end to the 3081/E's contribute negligible deadtime to the experiment.

We have obtained upper limits for the decays ${K}_{L}^{0}\ensuremath{\rightarrow}\ensuremath{\mu}e$ and ${K}_{L}^{0}\ensuremath{\rightarrow}\mathrm{ee}$. The limits on the branching ratios are $B({K}_{L}^{0}\ensuremath{\rightarrow}\ensuremath{\mu}e)<1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ and $B({K}_{L}^{0}\ensuremath{\rightarrow}ee)<1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ (90% C.L.). In a simultaneous search for the previously observed decay ${K}_{L}^{0}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\mu}$, we have identified two events.

In a search for the decay ${\mathit{K}}_{\mathit{L}}^{0}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, no candidates have been observed. We determine the sensitivity from the detected number of CP-violating ${\mathit{K}}_{\mathit{L}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ decays and place a 90% confidence level upper limit on the branching ratio of B(${\mathit{K}}_{\mathit{L}}^{0}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$,\ensuremath{\Vert}${\mathit{M}}_{\mathit{K}}$-${\mathit{M}}_{\mathit{e}\mathit{e}}$\ensuremath{\Vert}6 MeV/${\mathit{c}}^{2}$)\ensuremath{\le}4.1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$. This result is a significant improvement over previous measurements, although still above the standard model prediction of 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$.

In the $W+2,3$ jet data collected by Collider Detector at Fermilab during the 1992--1995 Fermilab collider run, 13 events were observed to contain a superjet when $4.4\ifmmode\pm\else\textpm\fi{}0.6$ events are expected. A previous article detailed the selection and the kinematical properties of these events. The present paper provides estimates of the probability that the kinematics of these 13 events is statistically consistent with the standard model prediction.

We present a brief account of the search for the Higgs boson at the three major colliders that have operated over the last three decades: LEP, the Tevatron, and the LHC.The experimental challenges encountered stemmed from the distinct event phenomenology as determined by the colliders energy and the possible values for the Higgs boson mass, and from the capability of these colliders to deliver as much collision data as possible to fully explore the mass spectrum within their reach.Focusing more on the hadron collider searches during the last decade, we discuss how the search for the Higgs boson was advanced through mastering the experimental signatures of standard theory backgrounds, through the comprehensive utilization of the features of the detectors involved in the searches, and by means of advanced data analysis techniques.The search culminated in 2012 with the discovery, by the ATLAS and CMS collaborations, of a Higgs-like particle with mass close to 125 GeV, confirmed more recently to have properties consistent with those expected from the standard theory Higgs boson.

In Run 1 at the LHC, the search for the Higgs boson decay into by the ATLAS and CMS experiments has resulted in the observation of a small excess of events consistent with the expectation from the production of a Standard Model Higgs boson with a mass of ≈ 125 GeV. The significance of this excess is below the 3σ level, compatible with the expected sensitivity. This chapter summarizes the essential elements of these challenging analyses: the production processes studied, the techniques used in the analyses, and the prospects for the observation of H → in Run 2 of the LHC.

We propose a Tevatron Run III Program that would extend the operations of the Tevatron Collider Program for three years from the end of 2011 through 2014, with the major goal of providing greater than 3 evidence for the low mass Standard Model Higgs Boson in its dominant decay channel, b ¯. Failure to detect evidence for a Higgs signal at the end of Run III will provide conclusive proof of physics beyond the Standard Model. Such a Tevatron Run III can be done in parallel with simultaneous running of NO A up to 71% of the requested 700 kW power, with small and low-cost modifications to the Main Injector/Recycler complex. In addition to providing at least a 3 evidence of the Higgs Boson in the low mass range, should it exist, the purpose of Run III is to: (1) more than double the currently existing data sets of both collaborations up to a total integrated (analyzed) luminosity of 16 fb 1 ; (2) extend the program to the estimated end-point of the useful operational span of the current detectors without a significant upgrade cycle; (3) provide Fermilab with an additional outflow of exciting, rich and new results, and continued training of students and RA’s, during the transition to the Intensity Frontier.

Abstract We present a flexible and scalable approach to address the challenges of charged particle track reconstruction in real-time event filters (Level-1 triggers) in collider physics experiments. The method described here is based on a full-mesh architecture for data distribution and relies on the Associative Memory approach to implement a pattern recognition algorithm that quickly identifies and organizes hits associated to trajectories of particles originating from particle collisions. We describe a successful implementation of a demonstration system composed of several innovative hardware and algorithmic elements. The implementation of a full-size system relies on the assumption that an Associative Memory device with the sufficient pattern density becomes available in the future, either through a dedicated ASIC or a modern FPGA. We demonstrate excellent performance in terms of track reconstruction efficiency, purity, momentum resolution, and processing time measured with data from a simulated LHC-like tracking detector.

A major upgrade is proposed for the CDF detector in order to exploit fully the physics opportunities of high luminosity running at the Fermilab Collider.

Abstract

The Time-of-Flight (TOF) detector measures the arrival time and deposited energy of charged particles reaching scintillator bars surrounding the central tracking region of the CDF detector. Requiring high ionization in the TOF system provides a unique trigger capability, which has been used for a magnetic monopole search. Other uses, with smaller pulse height thresholds, include a high-multiplicity charged-particle trigger useful for QCD studies and a much improved cosmic ray trigger for calibrating other detector components. Although not designed as input to CDF's global Level 1 trigger, the TOF system has been easily adapted to this role by the addition of 24 cables, new firmware, and four custom TOF trigger boards (TOTRIBs). This article describes the TOF trigger.

The results on the measurements of the top-quark mass, based on the data collected by the Tevatron experiments CDF and DO at Fermilab during Run I from 1992 to 1996, are summarized. The combination of the published results, taking correlated uncertainties properly into account, is presented. The resulting world average for the mass of the top quark is: $M_t = 178.0 \pm 4.3 GeV/c^2$, where the total error of consists of a statistical part of $2.7 GeV/c^2$ and a systematic part of $3.3 GeV/c^2$.

In this article I summarize the lectures given at the XI School of Particles and Fields in Xalapa, Mexico, in August 2004. By necessity descriptions and details are kept brief. Emphasis is made on key issues relevant to the most up-to-date experimental results from Run 2 at the Tevatron, the only place so far where one can study experimentally the intriguing top quark.

The CDF experiment was established at around 1977 and has now become a major international enterprise with about five hundred physicists from about fifty institutions from eleven different countries. Unfortunately no Latin-American institutions have so far become official members of the CDF experiment and even the contribution from individual Latin-American physicists has been limited. Here I describe briefly the status of the CDF experiment, the challenges it faces and outline the possibilities for new groups to help meet these challenges and partake in the very exciting future awaiting just around the corner.

In this paper we summarize the status of Top Quark Physics and of searches for the Standard Model Higgs at the Tevatron. Results from both the CDF and D0 experiments are discussed and the prospects for the upcoming Run 2, in the year 2001, are outlined. Much work has been performed on these topics and due to the nature of these proceedings only a brief explanation can be offered here. For more details the reader should turn to the excellent sources listed in the reference section.

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}

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}

In this paper we summarize the status of Top Quark Physics and of searches for the Standard Model Higgs at the Tevatron. Results from both the CDF and D0 experiments are discussed and the prospects for the upcoming Run 2, in the year 2000, are outlined. Much work has been performed on these topics and due to the nature of these proceedings only a brief explanation can be offered here. For more details the reader should turn to the excellent sources listed in the reference section.

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}

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 Jacobo Konigsberg; Experimental top quark physics. AIP Conf. Proc. 15 March 1997; 400 (1): 57–90. https://doi.org/10.1063/1.53240 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 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}

We present a measurement of the time-dependent asymmetry in the rate for {ovr B}{sup thinsp0}{sub d} versus B{sup 0}{sub d} decays to J/{psi}K{sup 0}{sub S} . A nonzero asymmetry would be an indication of CP violation, and within the standard model this may be used to measure the CP -violation parameter sin(2{beta}) . A total of 198{plus_minus}17 B{sup 0}{sub d}/{ovr B}{sup thinsp0}{sub d} decays were observed in p{ovr p} collisions at {radical} (s) =1.8 TeV by the CDF detector at the Fermilab Tevatron. B{sup 0}{sub d} and {ovr B}{sup thinsp0}{sub d} are distinguished by a technique based on charge correlations from hadronization of the b quark. Our analysis results in sin(2{beta})=1.8{plus_minus}1.1(stat ){plus_minus}0.3(syst) . {copyright} {ital 1998} {ital The American Physical Society }

The lifetimes of the B{sup {minus}} and {bar B}{sup 0} mesons are measured using the partially reconstructed semileptonic decays {bar B}{r_arrow}Dl{sup {minus}}{bar {nu}}X, where D is either a D{sup 0} or D{sup {asterisk}+} meson. The data were collected by the CDF detector at the Fermilab Tevatron collider during 1992{endash}1995 and correspond to about 110thinsppb{sup {minus}1} of {bar p}p collisions at {radical} (s) =1.8thinspTeV. We measure decay lengths and extract the lifetimes to be {tau}(B{sup {minus}})=1.637{plus_minus}0.058{sub {minus}0.043}{sup +0.045} ps and {tau}({bar B}{sup 0})=1.474{plus_minus}0.039{sub {minus}0.051}{sup +0.052}thinspps, and the ratio of the lifetimes to be {tau}(B{sup {minus}})/{tau}({bar B}{sup 0})=1.110{plus_minus}0.056{sub {minus}0.030}{sup +0.033}, where the first uncertainties are statistical and the second are systematic. {copyright} {ital 1998} {ital The American Physical Society}

We present results of a search for W{sup +}W{sup -} production through the leptonic decay channel W{sup +}W{sup -}{r_arrow}l{sup +}l{sup -}{nu}{ovr {nu}} in {ovr p}p collisions at {radical}(s)=1.8TeV. In a 108pb{sup -1} data sample recorded with the Collider Detector at Fermilab, five W{sup +}W{sup -} candidates are found with an expected standard model background of 1.2{plus_minus}0.3 events. The W{sup +}W{sup -} production cross section is measured to be {sigma}({ovr p}p{r_arrow} W{sup +}W{sup -})=10.2{sup +6.3}{sub -5.1}(stat){plus_minus}1.6(syst)pb, in agreement with the standard model prediction. Limits on WW{gamma} and WWZ anomalous couplings are presented. {copyright} {ital 1997} {ital The American Physical Society}

We search for the rare decay W{sup {plus_minus}}{r_arrow}D{sub s}{sup {plus_minus}}{gamma} in 82thinsppb{sup {minus}1} of p{bar p} collisions recorded with the Collider Detector at Fermilab. At the 95{percent} confidence level, we find an upper limit on the relative branching fraction to be {Gamma}(W{sup {plus_minus}}{r_arrow}D{sub s}{sup {plus_minus}}{gamma})/{Gamma}(W{sup {plus_minus}}{r_arrow}e{sup {plus_minus}}{nu}){lt}1.2{times}10{sup {minus}2}. {copyright} {ital 1998} {ital The American Physical Society}

We report the results of a search for technicolor using 110 pb{sup {minus}1} of p{ovr p} collisions recorded by the Collider Detector at Fermilab (CDF). In technicolor models containing a technifamily, color-octet technirhos enhance the pair production of color-triplet technipions, which behave as third-generation leptoquarks. From our previously reported search for third-generation leptoquarks, we present constraints on the production of color-triplet technipions and color-octet technirhos as a function of their masses. {copyright} {ital 1999} {ital The American Physical Society}

We present measurements of correlated b{bar b} cross sections, {mu}-{mu} correlations, the average B{sup 0}{bar B}{sup 0} mixing parameter {bar {chi}}, and a limit on the {ital CP}-violating parameter {epsilon}{sub B}. For these measurements, we use muon pairs from b{bar b} double semileptonic decays. The data used in this analysis were taken with the Collider Detector at Fermilab and represent an integrated luminosity of 17.4{plus_minus}0.6 pb{sup {minus}1}. The results concerning b{bar b} production correlations are compared to predictions of next-to-leading order QCD computations. {copyright} {ital 1997} {ital The American Physical Society}

We have searched for heavy neutral gauge bosons (Z{sup {prime}}) in dielectron and dimuon decay modes using 110 pb{sup {minus}1} of {ital {bar p}}{ital p} collisions at {radical}(s)=1.8 TeV collected with the Collider Detector at Fermilab. We present a limit on the production cross section times branching ratio of a Z{sup {prime}} boson decaying into dileptons as a function of Z{sup {prime}} mass. For mass M{sub Z{sup {prime}}}{gt}600 GeV /c{sup 2}, the upper limit is 40fb at 95% confidence level. We set the lower mass limits of 690, 590, 620, 595, 565, 630, and 600 GeV/c{sup 2} for Z{sup {prime}}{sub SM}, Z{sub {psi}}, Z{sub {eta}}, Z{sub {chi}}, Z{sub I}, Z{sub LR}, and Z{sub ALRM}, respectively. {copyright} {ital 1997} {ital The American Physical Society}

We have searched for the rare decay W{sup {plus_minus}}{r_arrow}{pi}{sup {plus_minus}}+{gamma} in 83 pb{sup {minus}1} of data taken in proton-antiproton collisions at {radical}(s) =1.8 TeV with the Collider Detector at Fermilab. We find three events in the signal region and estimate the background to be 5.2{plus_minus}1.5 events. We set a 95{percent} confidence level upper limit of 7{times}10{sup {minus}4} on the ratio of partial widths, {Gamma}(W{sup {plus_minus}}{r_arrow}{pi}{sup {plus_minus}}+{gamma})/{Gamma}(W{sup {plus_minus}}{r_arrow}e{sup {plus_minus}}+{nu}). {copyright} {ital 1998} {ital The American Physical Society}

The decay {Lambda}{sub b}{sup 0}{r_arrow}J/{psi}{Lambda} is observed in 110 pb{sup {minus}1} of p{bar p} collisions taken at {radical}(s)=1.8 TeV. These data are used to measure a {Lambda}{sub b}{sup 0} mass of 5621{plus_minus}4(stat){plus_minus}3(syst) MeV/c{sup 2}, and a mass difference between the {Lambda}{sub b}{sup 0} and the B{sup 0} of 340{plus_minus}5(stat){plus_minus}1(syst) MeV/c{sup 2}. The production cross-section times branching fraction for the decay {Lambda}{sub b}{sup 0}{r_arrow}J/{psi}{Lambda} relative to that for the decay B{sup 0}{r_arrow}J/{psi}K{sub S}{sup 0} has been measured to be 0.27{plus_minus}0.12(stat){plus_minus}0.05(syst). {copyright} {ital 1997} {ital The American Physical Society}

We present a measurement of Z{sup 0} boson and Drell-Yan production cross sections in {bar p}p collisions at {radical} (s) =1.8 TeV using a sample of 107 pb{sup {minus}1} accumulated by the Collider Detector at Fermilab. The Drell-Yan cross section is measured in the mass range of M{sub {mu}{mu}}{gt}40 GeV/c{sup 2}. We compare the measurements with the predictions of quantum chromodynamics in both leading order and next-to-leading order, incorporating the recent parton distribution functions. The measurements are consistent with the standard model expectations. {copyright} {ital 1999} {ital The American Physical Society}

We present a search for dilepton events from t{bar t} production with one electron or muon and one hadronically decaying {tau} lepton from the decay t{bar t}{r_arrow}(scr(l){nu}{sub scr(l)}) ({tau}{nu}{sub {tau}}) b{bar b}, (scr(l)=e,{mu}) , using the Collider Detector at Fermilab. In a 109 pb{sup {minus}1} data sample of p{bar p} collisions at {radical}(s)=1.8 TeV we expect {approximately}1 signal event and a total background of {approximately}2 events; we observe 4 candidate events (2 e{tau} and 2 {mu}{tau} ). Three of these events have jets identified as b candidates, compared to an estimated background of 0.28{plus_minus}0.02 events. {copyright} {ital 1997} {ital The American Physical Society}

We present a measurement of the mass difference [Delta]m[sub d] for the B[sup 0] meson and the statistical power of the [ital b] flavor tagging methods used. The measurement uses 90 pb[sup [minus]1] of data from p[bar p] collisions at [radical] (s) =1.8 TeV collected with the CDF detector. An inclusive lepton trigger is used to collect a large sample of [ital B] hadron semileptonic decays. The mass difference [Delta]m[sub d] is determined from the proper time dependence of the fraction of [ital B] hadrons that undergo flavor oscillations. The flavor at decay is inferred from the charge of the lepton from semileptonic [ital B] decay. The initial flavor is inferred by determining the flavor of the other [ital B] hadron produced in the collision, either from its semileptonic decay (soft-lepton tag) or from its jet charge. The measurement yields [Delta]m[sub d]=(0.500[plus minus]0.052[plus minus]0.043)[h bar] ps[sup [minus]1], where the first uncertainty is statistical and the second uncertainty is systematic. The statistical powers ([epsilon]D[sup 2]) of the soft-lepton and jet-charge flavor taggers are (0.91[plus minus]0.10[plus minus]0.11)[percent] and (0.78[plus minus]0.12[plus minus]0.08)[percent], respectively. [copyright] [ital 1999] [ital The American Physical Society]

We search for new particles that decay into b{ovr b} and are produced with W bosons in p{ovr p} collisions at {radical}(s)=1.8 TeV . The search uses 109{plus_minus}7 pb{sup {minus}1} accumulated by the CDF experiment at Fermilab. We select events with an e{nu} or {mu}{nu} , and two jets, one of them b tagged. The number of events and the two-jet mass distribution are consistent with expectations. Using W+Higgs production as a model for the acceptance, we set an upper limit on the production cross section times branching ratio for the new particle ranging from 14 to 19pb (95{percent} C.L.) as the particle mass varies from 70 to 120 GeV/c{sup 2} . {copyright} {ital 1997} {ital The American Physical Society}

B{sub d}{sup 0}-{bar B}{sub d}{sup 0} oscillations are observed in {open_quotes}self-tagged{close_quotes} samples of partially reconstructed B mesons decaying into a lepton and a charmed meson collected in p{bar p} collisions at {radical} (s) =1.8thinspTeV. A flavor tagging technique is employed which relies upon the correlation between the flavor of B mesons and the charge of a nearby particle. We measure the flavor oscillation frequency to be {Delta}m{sub d}=0.471{sub {minus}0.068}{sup +0.078}{plus_minus}0.034thinspps{sup {minus}1}. The tagging method is also demonstrated in exclusive samples of B{sub u}{sup +}{r_arrow}J/{psi}K{sup +} and B{sub d}{sup 0}{r_arrow}J/{psi}K{sup {asterisk}0}(892), where similar flavor-charge correlations are observed. The tagging characteristics of the various samples are compared with each other, and with Monte Carlo simulations. {copyright} {ital 1998} {ital The American Physical Society}

The lifetime of the B{sub S}{sup 0} meson is measured using the semileptonic decay B{sub S}{sup 0}{r_arrow}D{sub S}{sup {minus}}l{sup +}{nu}X. The data sample consists of about 110 pb{sup {minus}1} of p{bar p} collisions at {radical} (s) =1.8 TeV collected by the CDF detector at Fermilab. Four different D{sub S}{sup {minus}} decay modes are reconstructed resulting in approximately 600 D{sub S}{sup {minus}}l{sup +} signal events. The B{sub S}{sup 0} meson lifetime is determined to be {tau}(B{sub S}{sup 0})=(1.36{plus_minus}0.09{sub {minus}0.05}{sup +0.06}) ps, where the first and second uncertainties are statistical and systematic, respectively. The B{sub S}{sup 0} meson decay length distribution is examined for a lifetime difference {Delta}{Gamma}/{Gamma} between the two mass eigenstates of the B{sub S}{sup 0} meson. An upper limit of {Delta}{Gamma}/{Gamma}{lt}0.83 is set at the 95{percent} confidence level. {copyright} {ital 1999} {ital The American Physical Society}

We present a measurement of the mass difference {Delta}m{sub d} of the two B{sub d}{sup 0} mass eigenstates. We use a flavor tagging method based on the lepton charge, in a sample of events with two muons at low transverse momentum. The sample corresponds to an integrated luminosity of 90 pb{sup {minus}1} collected by the Collider Detector at Fermilab. The result obtained is {Delta}m{sub d}=0.503{plus_minus}0.064(stat){plus_minus}0.071(syst) ps{sup {minus}1}. thinsp {copyright} {ital 1999} {ital The American Physical Society}

We present a measurement of the t{bar t} production cross section in p{bar p} collisions at {radical}(s)=1.8 TeV using an integrated luminosity of 109 pb{sup {minus}1} collected with the Collider Detector at Fermilab. The measurement uses t{bar t} decays into final states which contain one or two high transverse momentum leptons and multiple jets, and final states which contain only jets. Using acceptances appropriate for a top quark mass of 175 GeV/c{sup 2} , we find {sigma}{sub t{bar t}}=7.6{sup +1 .8}{sub {minus}1.5} pb . {copyright} {ital 1998} {ital The American Physical Society}

We search for the flavor-changing neutral current decays of the top quark t{r_arrow}q{gamma} and t{r_arrow}qZ (here q represents the c and u quarks) in {bar p}p collisions at {radical}(s)=1.8 TeV . We use a dataset ({integral}Ldt{approximately}110 pb{sup {minus}1}) collected during the 1992{endash}1995 run of the Collider Detector at Fermilab. We set 95{percent} confidence level limits on the branching fractions B(t{r_arrow}q{gamma}){lt}3.2{percent} and B(t{r_arrow}qZ){lt}33{percent} , consistent with the standard model. {copyright} {ital 1998} {ital The American Physical Society}

We present a study of events with W bosons and hadronic jets produced in {bar p}p collisions at a center of mass energy of 1.8TeV. The data consist of 51400 W{sup {plus_minus}}{r_arrow}e{sup {plus_minus}}{nu} decay candidates from 108 pb{sup {minus}1} of integrated luminosity collected using the CDF detector at the Fermilab Tevatron Collider. Cross sections and jet production properties have been measured for W+{ge}1 to {ge}4 jet events. The data are compared to predictions of leading-order QCD matrix element calculations with added gluon radiation and simulated parton fragmentation. {copyright} {ital 1997} {ital The American Physical Society}

We present a search for the flavor-changing neutral current decays B{sub d}{sup 0}{r_arrow}{mu}{sup +}{mu}{sup {minus}} and B{sub s}{sup 0}{r_arrow}{mu}{sup +}{mu}{sup {minus}} in p{bar p} collisions at {radical} (s) =1.8TeV, using 98pb{sup {minus}1} of data collected at the Collider Detector at Fermilab. We find one candidate event for these decays, which is consistent with the background estimates, and set upper limits on the branching fractions of B(B{sub d}{sup 0}{r_arrow}{mu}{sup +}{mu}{sup {minus}}){lt}8.6{times}10{sup {minus}7} and B(B{sub s}{sup 0}{r_arrow}{mu}{sup +}{mu}{sup {minus}}){lt}2.6{times}10{sup {minus}6} at 95{percent} confidence level. {copyright} {ital 1998} {ital The American Physical Society}

We have searched for the decays B{sup 0}{sub s}{r_arrow}e{sup {plus_minus}}{mu}{sup {minus_plus}} and B{sup 0}{sub d}{r_arrow}e{sup {plus_minus}}{mu}{sup {minus_plus}} using a 102 pb{sup {minus}1} data sample of p{ovr p} collisions at {radical} (s) =1.8 TeV collected with the Collider Detector at Fermilab. We set upper limits on the branching fractions of B(B{sup 0}{sub s}{r_arrow}e{sup {plus_minus} }{mu}{sup {minus_plus}}){lt}6.1(8.2) {times}10{sup {minus}6} and B(B{sup 0}{sub d}{r_arrow}e{sup {plus_minus} }{mu}{sup {minus_plus}}){lt}3.5(4.5) {times}10{sup {minus}6} at 90(95){percent} confidence level. Using these limits, we set lower bounds on the corresponding Pati-Salam leptoquark masses and find that M{sub LQ}(B{sup 0}{sub s}) {gt}20.7(19.3) TeV /c{sup 2} and M{sub LQ}(B{sup 0}{sub d}) {gt}21.7(20.4) TeV /c{sup 2} at 90(95){percent} confidence level. {copyright} {ital 1998} {ital The American Physical Society }

The K0L → π0e+e− process has recently been the subject of renewed consideration by both experimentalists and theoreticians. The basic ideas that motivate this search are described, together with the characteristic features of high sensitivity experiments. In particular we detail the K0L → π0e+e− branch of the BNL-791 experiment. We also discuss the sensitivity of the currently running experiments as well as of the newly proposed ones.

Tau detection techniques in hadron colliders are discussed together with the measurements and searches performed so far. We also underline the importance tau physics has in present and future collider experiments.