A. Korytov

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.

This Report summarizes the proceedings of the 2015 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) the new PDF4LHC parton distributions, (III) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (IV) a host of phenomenological studies essential for comparing LHC data from Run I with theoretical predictions and projections for future measurements in Run II, and (V) new developments in Monte Carlo event generators.

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb−1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb−1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.

The importance of the $H\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}4\ensuremath{\ell}$ ``golden'' channel was shown by its major role in the discovery, by the ATLAS and CMS collaborations, of a Higgs-like boson with mass near 125 GeV. We analyze the discrimination power of the matrix element method both for separating the signal from the irreducible $ZZ$ background and for distinguishing various spin and parity hypotheses describing a signal in this channel. We show that the proper treatment of interference effects associated with permutations of identical leptons in the $4e$ and $4\ensuremath{\mu}$ final states plays an important role in achieving the best sensitivity in measuring the properties of the newly discovered boson. We provide a code, mekd, that calculates kinematic discriminants based on the full leading-order matrix elements and which will aid experimentalists and phenomenologists in their continuing studies of the $H\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}4\ensuremath{\ell}$ channel.

We present a general procedure for measuring the tensor structure of the coupling of the scalar Higgs-like boson recently discovered at the LHC to two Z bosons, including the effects of interference among different operators. To motivate our concern with this interference, we explore the parameter space of the couplings in the effective theory describing these interactions and illustrate the effects of interference on the differential dilepton mass distributions. Kinematic discriminants for performing coupling measurements that utilize the effects of interference are developed and described. We present projections for the sensitivity of coupling measurements that use these discriminants in future LHC operation in a variety of physics scenarios.

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.

Studies of Cathode Strip Chamber longevity, comparing Ar+CO2 gas mixtures with fractions of 5%, 2%, and 0% CF4, were performed using several small cathode strip prototype chambers. In each trial, a localized source of radiation was used to irradiate up to an accumulated charge of about 300 mC/cm. Additionally, longevity of a uniformly irradiated prototype operating with 2% CF4 was studied at the CERN Gamma Irradiation Facility GIF++. Post-hoc analysis of the chamber electrodes using spectroscopy techniques was also done.

Abstract Studies of cathode strip chamber longevity, comparing Ar+CO $$_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msub> </mml:math> gas mixtures with fractions of 5%, 2%, and 0% CF $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>4</mml:mn> </mml:msub> </mml:math> , were performed using several small cathode strip prototype chambers. In each trial, a localized source of radiation was used to irradiate up to an accumulated charge of about 300 mC/cm. Additionally, longevity of a uniformly irradiated prototype operating with 2% CF $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>4</mml:mn> </mml:msub> </mml:math> was studied at the CERN Gamma Irradiation Facility GIF++. Post-hoc analysis of the chamber electrodes using spectroscopy techniques was also done.

In this work the design of a constant fraction discriminator (CFD) to be used in the VFAT3 chip for the read-out of the triple-GEM detectors of the CMS experiment, is described. A prototype chip containing 8 CFDs was implemented using 130 nm CMOS technology and test results are shown.

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

This Report summarises the activities of the SM and working group for the Workshop Physics at TeV Colliders, Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

This contribution introduces a new type of Micropattern Gaseous Detector, the Fast Timing Micropattern (FTM) detector, utilizing fully Resistive WELL structures. The structure of the prototype will be described in detail and the results of the characterization study performed with an X-ray gun will be presented, together with the first results on time resolution based on data collected with muon/pion test beams.

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.

Presented are the main design features of the large Cathode Strip Chambers (CSCs) for the CMS Endcap Muon System as well as the performance results obtained with the two full-scale 3.4×1.5 m2 six-plane prototypes. The prototype performance was within the baseline requirements: (a) higher than 99% efficiency of muon track finding at the trigger level with more than 92% probability for bunch crossing identification and better than 2 mm spatial resolution, and (b) better than 150 μm spatial resolution in off-line.

The "golden" channel, in which the newly-discovered Higgs boson decays to four leptons by means of intermediate vector bosons, is important for determining the properties of the Higgs boson and for searching for subtle new physics effects. Different approaches exist for parametrizing the relevant Higgs couplings in this channel; here we relate the use of pseudo-observables to methods based on specifying the most general amplitude or Lagrangian terms for the $HVV$ interactions. We also provide projections for sensitivity in this channel in several novel scenarios, illustrating the use of pseudo-observables, and analyze the role of kinematic distributions and (ratios of) rates in such $H\to4\ell$ studies.

Aging of CMS muon cathode strip chamber prototypes under sustained irradiation was studied. The tests were performed with three prototypes of different gas seal designs and with three gas mixtures Ar(30%)+CO2(50%)+CF4(20%), Ar(30%)+CO2(70%) and Ar(40%)+CO2(50%)+CF4(10%). The CF4-containing mixtures showed no or little aging for an overall accumulated charge per unit of wire length in excess of 13C/cm. In comparison, the performance deterioration in the Ar–CO2 mixture proved to be very dramatic: the gas gain falls by a factor of 2 for each 0.25C/cm of accumulated charge.

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.

Abstract We studied profile-based detectors with external pick-up strips (Iarocci-type tubes) with the purpose to find out if they can be used as detectors of large area and high spatial resolution. In this paper we summarize our measurements and calculations. Contributions of different factors in the spatial resolution were theoretically evaluated. The resolution of ∼ 45 μm in the proportional mode and ∼ 100 μm in the limited streamer mode were obtained in a laser beam. The former was limited by electronic noise and the latter by the intrinsic streamer fluctuations. The resolution of ∼ 80 μm in proportional mode was achieved in a muon beam (by subtracting the electronic noise contribution, we estimate that the limit for our prototype was around 60–65 μm).

A simple network of comparators applied to the strip signals of a cathode strip chamber allows quick hit localization to within a halfstrip width, or ± a quarter-strip. A six-plane chamber with 6.4 mm wide strips was tested in a high-energy muon beam. The chamber was placed behind a 30 cm thick iron block. We show that patterns of hits localized to within a halfstrip allowed us to identify 300 GeV/c muon tracks with 99% probability and 0.7 mm spatial resolution in the presence of bremsstrahlung radiation. This technique of finding muon tracks will be used in the cathode strip chambers of the CMS Endcap Muon System.

In order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS. Following an extensive R&D program, CMS has identified triple-foil gas electron multiplier (GEM) detectors as a solution for the first muon station in the region 1.6<|η|<2.2, while continuing R&D is ongoing for additional regions.

This is the TeV4LHC report of the Physics Landscapes Working Group, focused on facilitating the start-up of physics explorations at the LHC by using the experience gained at the Tevatron. We present experimental and theoretical results that can be employed to probe various scenarios for physics beyond the Standard Model.

A novel approach which uses Fiber Bragg Grating (FBG) sensors has been utilized to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

In the Compact Muon Solenoid (CMS) experiment, muon detection in the forward direction is accomplished by cathode strip chambers (CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using 36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge (MTCC) exercise conducted by the CMS experiment in 2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<0.01m2), results presented in this paper were obtained by many installed CSCs operating in situ over an area of ≈23m2 as a part of the CMS experiment. The efficiency of finding two-dimensional trigger primitives within six-layer chambers was found to be 99.93±0.03%. These segments, found by the CSC electronics within 800 ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System.

In this note, we propose an algorithm for fast and efficient track segment reconstruction in Cathode Strip Chambers used by the Compact Muon Solenoid experiment for muon detection in the forward direction. The algorithm is designed to be CPU-efficient and is targeted for High Level Trigger (HLT, online reconstructed events pre-selection) purposes. The segment finding efficiency and the spatial resolution attainable with the proposed algorithm as well as the required CPU time are benchmarked using the Cosmics Muon data and found to surpass the HLT requirements.

The Compact Muon Solenoid (CMS) detector is one of the two general-purpose detectors at the CERN LHC. LHC will provide exceptional high instantaneous and integrated luminosity after second long shutdown. The forward region |η| ≥ 1:5 of CMS detector will face extremely high particle rates in tens of kHz/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and hence it will affect the momentum resolution, efficiency and longevity of the muon detectors. Here, η is pseudorapidity defined as η = −ln(tan(θ/2)), where θ is the polar angle measured from z-axis. To overcome these issues the CMSGEM collaboration has proposed to install new large size rate capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of CMS muon system. The first set of Triple GEM detectors will be installed in the GE1/1 region (1:6 < |η| < 2.2) of the muon endcap during the long shutdown 2 (LS2) of the LHC. Towards this goal, full size CMS Triple GEM detectors have been fabricated and tested at the CERN SPS, H2 and H4 test beam facility. The GEM detectors were operated with two gas mixtures: Ar/CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (70/30) and Ar/CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /CF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> (45/15/40). In 2014, good quality data was collected during test beam campaigns. In this paper, the performance of the detectors is summarized based on their tracking efficiency and time resolution.

We put forth conclusions and suggestions regarding the presentation of the LHC Higgs results that may help to maximize their impact and their utility to the whole High Energy Physics community.

It is shown that the polishing of the graphite cathodes of plastic streamer tubes increases their operational stability.

The CMS experiment at LHC will upgrade its forward muon spectrometer by incorporating Triple-GEM detectors. This upgrade referred to as GEM Endcap (GE1/1), consists of adding two back-to-back Triple-GEM detectors in front of the existing Cathode Strip Chambers (CSC) in the innermost ring of the endcap muon spectrometer. Before the full installation of 144 detectors in 2019–2020, CMS will first install ten single chamber prototypes during the early 2017. This pre-installation is referred as the slice test. These ten detectors will be read-out by VFAT2 chips [1]. On-detector there is also a FPGA mezzanine card which sends VFAT2 data optically to the μTCA back-end electronics. The correct and safe operation of the GEM system requires a sophisticated and powerful online Detector Control System, able to monitor and control many heterogeneous hardware devices. The DCS system developed for the slice test has been tested with CMS Triple-GEM detectors in the laboratory. In this paper we describe the newly developed DCS system and present the first results obtained in the GEM assembly and quality assurance laboratory.

We report on the results of testing two six-layer 0.6 × 0.6 m2 cathode strip chamber (CSC) prototypes in a muon beam at CERN. The prototypes were designed to simulate sections of the end-cap muon system of the Compact Muon Solenoid (CMS) detector which will be installed at the Large Hadron Collider (LHC). We measured the spatial and time resolutions of each chamber for different gains, different orientations with respect to the beam direction and different strength magnetic fields. The single-layer spatial resolution of a prototype with a strip pitch of 15.88 mm ranged from 78 to 468 μm, depending on whether the particle passed between two cathode strips or through the center of a strip; its six-layer resolution was found to be 44 μm. The single-layer spatial resolution of a prototype with a strip pitch of 6.35 mm ranged from 54 to 66 μm; its six-layer resolution was found to be 23 μm. The efficiency for collecting an anode wire signal from one of six layers within a 20 ns time window appropriate for the LHC was found to be greater than 95% in normal running conditions.

Presented is an overview of muon systems used at ee-, pp-, and ep-colliders, with the focus on experiments from the recent past, present, and near-term future. The review highlights similarities and differences of the muon system conceptual designs, the choices of detector technologies, and the attained or foreseen performance. The encountered performance problems are also discussed.

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m 2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.

For the High Luminosity LHC CMS is planning to install new large size Triple-GEM detectors, equipped with a new readout system in the forward region of its muon system (1.5<|η|<2.2). In this note we report on the status of the project, the main achievements regarding the detectors as well as the electronics and readout system.

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.

We put forth conclusions and suggestions regarding the presentation of the LHC Higgs results that may help to maximize their impact and their utility to the whole High Energy Physics community.

Presented are the main design features of the large cathode strip chambers (CSCs) for the CMS endcap muon system as well as the performance results obtained with the first large-scale prototype. The 3.4×1.2 m2 six-plane prototype has been reliably operated over one year and the cosmic-ray tests showed that it was capable of detecting muons with ∼80 μm spatial and ∼5 ns time resolutions.

The production, installation, and testing of 468 cathode strip chambers for the endcap muon system of the CMS experiment played a critical role in the preparation of the endcap muon system for the final commissioning. Common testing procedures and sets of standard equipment were used at 5 international assembly centers. The chambers were then thoroughly retested after shipment to CERN. Final testing was performed after chamber installation on the steel disks in the CMS detector assembly building. The structure of the detector quality control procedure is presented along with the results of chamber performance validation tests.

The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&amp;D and moving to production. An unprecedented large area of several 100 m 2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

The design and performance of a large scale (1 × 4 m2) muon drift chamber prototype for the GEM Detector are presented. The cosmic ray tests showed a spatial resolution of 80 μm by drift time measurements and resolution of 10 cm along the wires by time difference technique. The possibility of an accurate timing trigger from the chamber was tested on experimental data.

The performance of a drift chamber based on limited streamer tubes was studied. Results obtained with single tubes and a four-layer prototype are presented. Described are the spatial resolutions and drift times for different gases including non-flammable ones, rate capability, neutron and photon sensitivity, aging, after-pulsing for different cathode materials, magnetic field effects and some other features.

Abstract The influence of different factors, such as pressure and temperature, slight changes in a gas mixture, self-sustaining discharge, aging and different deviations in the detector geometry, on the operation of the DELPHI plastic streamer tubes was studied. The contributions of these factors to the energy resolution of the DELPHI hadron calorimeter were estimated. The major influence was found to be due to atmospheric pressure fluctuations. The scale of a signal change is ∼±1% per ∓1 Torr, which is comparable with the intrinsic resolution of the hadron calorimeter of ∼8–10% at 100 GeV. The question of the choice of a gas mixture was studied as well. The maximum streamer charge was shown to be independent of component concentrations in the Ar:CO2:isobutane (or n-pentane) gas mixtures.

During the future LHC upgrade planned in 2018, the forward endcap region of the CMS muon spectrometer will be upgraded with GEM chambers. GEM technology is able to withstand the radiation environment expected in the forward region. The GE1/1 station will be included in the muon L1 trigger, allowing to keep low p(T) threshold even at high luminosity. Moreover, it will bring detection redundancy in the most critical part of the CMS muon system, along with benefits to muon reconstruction performance.

The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on cham design features and will discuss the performance of the upgraded detector.

The Compact Muon Solenoid (CMS) detector installed at the CERN Large Hadron Collider (LHC) has an extensive muon system which provides information simultaneously for identification, track reconstruction and triggering of muons. As a consequence of the extreme particle rate and high integrated charge, the essentiality to upgrade the LHC has given rise to the High Luminosity phase of the LHC (HL-LHC) project so that the CMS muon system will be upgraded with superior technological challenges. The CMS GEM collaboration offers a solution to equip the high-eta region of the muon system for Phase 2 (after the year 2017) with large-area triple-layer Gas Electron Multiplier (GEM) detectors, since GEMs have the ability to provide robust and redundant tracking and triggering functions with an excellent spatial resolution of order 100 micron and a high particle rate capability, with a close to 100% detection efficiency. In this contribution, the present status of the triple-GEM project will be reviewed, and the significant achievements from the start of the R&D in 2009 will be emphasized.

In their searches for the Standard Model (SM) Higgs boson in the mass range 115-1000 GeV, both ATLAS and CMS Collaborations observed a narrow four-lepton resonance with a mass near 125 GeV with local significances in excess of 5σ.In the combination of the ATLAS and CMS H → ZZ → 4 measurements, the mass of the observed boson was found to be 125.15± 0.37 (stat) ± 0.15 (syst) GeV.The event rates attributed to the signal and the studied differential cross sections were compatible with the SM Higgs boson hypothesis.Kinematic properties of leptons in signal candidate events agreed with those expected for a state with spinparity quantum numbers of the SM Higgs boson (J P = 0 + ) and strongly disfavoured states with alternative quantum numbers or 0 + states with non SM-like tensor structures of their couplings to Z bosons.The yield and kinematic properties of events in the high four-lepton mass region allowed one to probe off-shell production of the discovered boson and set model-dependent upper limits on its total width.* In this chapter, intermediate on-shell and off-shell Z bosons as well as γ * , when allowed, are commonly referred to as Z, unless explicitly stated otherwise.* * Technically, pdf s used in construction of unbinned likelihoods to describe the overall event probability density are checked to be positive definite, where data events are observed.This effectively limits the magnitude of possible negative values of µ V for a given

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.

For the LHC High Luminosity phase (HL-LHC) the CMS GEM Collaboration is planning to install new large size triple-GEM detectors in the forward region of the muon system (1.5<|η|<2.2) of the CMS detector.The muon reconstruction with triple-GEM chambers information included have been successfully integrated in the official CMS software, allowing physics studies to be carried out.The new sub-detector will be able to cope the extreme particle rates expected in this region along with a high spatial resolution.The resulting benefit in terms of triggering and tracking capabilities has been studied: the expected improvement in the performance of the muon identification and track reconstruction as well as the expected improvement coming from the lowering of the muon p T trigger tresholds will be presented.The contribution will review the status of the CMS upgrade project with the usage of GEM detector, discussing the trigger, the muon reconstruction performance and the impact on the physics analyses.

The influence of the magnetic field on the self-quenching streamer discharge characteristics was investigated. The effect is several percent in a field of about 10 kG.

Abstract We have studied the achievable spatial resolution of a plastic streamer tube with pickup strips perpendicular to the anode wire. Making use of the fact that low cathode resistivity and/or large integration time broaden the induced charge distribution, we have obtained a spatial resolution better than 400 μm for ∼ 3 cm wide strips. This value is comparable with the best results ( ∼ 350–450 μm) obtained with the usual ∼ 1 cm wide strips.

A novel, simple, and inexpensive multi-point two-coordinate alignment technique based on a stretched wire approach is proposed for the axial alignment of the GEM muon chambers. The concept was simulated and tested in a laboratory. Over a very wide range (∼ 10 mm) of possible displacements in two directions (orthogonal to the wire), this technique is capable of providing an accuracy of a few microns for one of them and a few tens of microns for the other.

Presented are the results of the most recent studies by the CMS and ATLAS collaborations on the expected sensitivity of their detectors to observing a Higgs boson at LHC. The overview is preceded with a brief summary of the LHC and the CMS Experiment status.

Should an event excess compatible with the H → ZZ(∗) → 4μ decay channel be observed at LHC, the statistical significance of the access must be properly scaled down to account for the systematic errors and the fact that the search is performed in a wide-open range of possible Higgs boson masses. We present results of studies addressing both of the two contributions and show that the required corrections in Higgs boson search in this particular channel are by far not negligible.

The procedure and results of mass testing of plastic streamer tubes for the DELPHI hadron calorimeter are described in detail. The mass testing includes three stages: high voltage test and conditioning, X-ray test on radiation load capability and wire tension control in ready detectors. The productivity of the test workshop was 240 detectors per day at maximum. After testing of about 25 000 streamer tubes, 8% have been rejected on the ground of severe rejection criteria which exceed significantly the working conditions in the DELPHI experiment.

The performance of a drift tube prototype in a 0.5 TeV/c muon beam was studied. Presented is a comparison of experimental data with a GEANT simulation in order to determine the validity of the Monte Carlo in simulating the detector performance in the presence of the electromagnetic contamination associated with high energy muons. The Monte Carlo simulation generally was with few exceptions in 30% or better agreement with the data.

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.

Presented are the Tevatron Run I QCD results that have been known for the degree of controversy associated with them. Also, the prospects for the QCD-motivated studies at Tevatron Run II and LHC are briefly discussed.

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}

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}

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 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}

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 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}