A. Yagil

Using the ARGUS detector at the DORIS II storage ring we have searched in three different ways for B0-B0 mixing in ϒ (4S) decays. One explicitly mixed event, a decay ϒ (4S)→B0B0, has been completely reconstructed. Furthermore, we observe a 4.0 standard deviation signal of 24.8 events with like-sign lepton pairs and a 3.0 standard deviation signal of 4.1 events containing one reconstructed B0(B0) and an additional fast ℓ+(ℓ)−. This leads to the conclusion that B0-B0 mixing is substantial. For the mixing parameter we obtain r=0.21±0.08.

The Central Outer Tracker is a large cylindrical drift chamber constructed to replace Collider Detector at Fermilab's original central drift chamber for the higher luminosity expected for Run 2 at the Fermilab Tevatron. The chamber's drift properties are described in the context of meeting the operating requirements for Run 2. The design and construction of the chamber, the front-end readout electronics, and the high-voltage system are described in detail. Wire aging considerations are also discussed.

Using the ARGUS detector at the e+e− storage ring DORIS II, we have observed the decay τ−→π−π−π−π+π+ντ in tau-pair events produced at center-or-mass energies between 9.4 and 10.6 GeV. From the 5π invariant mass distribution we derive an upper limit of m(ντ)<35 MeV/c2 at the 95% confidence level. The branching ratio for this decay channel is found to be (0.064±0.023±0.01)%.

B mesons have been reconstructed in five decay channels of the type B→D∗±nπ(n=1,2,3) using data accumulated by the ARGUS experiment at the e+e− storage ring DORIS II at DESY. In total, we find 40 neutral B mesons above a background of 15±6 events with a mass of (5278.2±1.0±3.0) MeV/c2 and 32 charged B mesons above a background of 17±6 events with a mass of (5275.8±1.3±3.0) MeV/c2. The decays B0D∗+π−π0, B0D∗+π−π−π+, and B−→D∗+π−π−π0 have been observed for the first time. We find substantially smaller branching ratios for the decay modes B0→D∗+π− and B−→D∗+π−π− than previously published by the CLEO collaboration.

Using the ARGUS detector at the e+e− storage ring DORIS II at DESY we have investigated the decays B0→D∗−e+v and B0→D∗−μ+ν. The B0 mesons were produced in 39600 ϒ(4S)→B0B0 decays. Assuming electron-muon universality we obtain a branching ratio BR(B0→D∗−e+v)=BR(B0→D∗−γm+ν)=(7.0±1.2±1.9)%.

Using the ARGUS detector at the e+e− storage ring DORIS II, we have observed charmless decays of B mesons into the final states pp̄π± and pp̄π+π−. The significance of the signal corresponds to more than five standard deviations. The branching ratios are (5.2±1.4±1.9)×10−4 for the three-body and (6.0±2.0±2.2)×10−4 for the four-body final state. These decays cannot proceed via the dominant b→c transitions, and we show that they are not the result of penguin-type processes. Thus, the observed decays must represent b→u quark transitions. Consequently, the Kobayashi-Maskawa matrix element Vub is non-zero.

Using the ARGUS detector at DORIS II, we have analyzed tau decays into π−π−π+π0ντ. The branching ratio was determined to be (4.2±0.5±0.9)%. From a study of the three pion sub-system, we find evidence for the decay τ−→ωπ−ντ with a branching ratio of (1.5±0.3±0.3)%. The ωπ− system is found to be predominantly in a JP=1− state. There is no evidence for second-class axial-vector currents. The spectral function for the ωπ− final state is in agreement with a prediction based on CVC and σe+e−→ωπ0.

Using the ARGUS detector at the e +e− storage ring DORIS II, we have studied the colour-suppressed decays B→Jψ X and B→ψ′ X. We find the inclusive branching ratios for these two channels to be (1.07±0.16±0.19) % and (0.46±0.17±0.11) %, respectively. From a sample of reconstructed exclusive events the masses of the B0 and B+ mesons are determined to be (5279.5±1.6±3.0) MeVc2 and (5278.5±1.8±3.0) MeVc2, respectively. Branching ratios are determined from five events of the type B0→Jψ K∗0 and three of B+→J/ψ K+. In the same data sample a search for B0→e+e−, μ+μ− and μ±e∓ leads to upper limits for such decays.

The impact of the ARGUS experiment to elementary particle physics is reviewed. More than ten years of data taking has allowed ARGUS to contribute significantly to our understanding of beauty and charmed hadrons, τ Leptons, ϒ mesons, ϒϒ interactions and fragmentation processes. In particular the ARGUS measurements of CKM matrix elements opened up a new window on the Standard Model.

Using the ARGUS detector at DORIS II, we have studied the production of the charmed baryon Λc in e+e− annihilation at centre-of-mass energies near 10 GeV. The Λc+ was seen in the three decay modes pK−π+, Λπ+π−π+ and K̄0p, with products of normalized cross section times branching ratio [R·Br] of (10.8±1.4±1.2)×10−3, 6.6±1.5±0.9)×10−3 and (6.7±1.4±0.8)×10−3 respectively. The measured mass for the Λc was (2283.1±1.7±2.0) MeV/c2. A limit on the decay rates to Λπ+ is reported. The fragmentation function of the Λc was measured.

Using the ARGUS detector at the e+e− storage ring DORIS II, we have investigated the decay B0→D−ℓ+ν, where ℓ+ is e+ or μ+. The B0 mesons were produced in 150 000 ϒ(4S) decays. Assuming electron-muon universality we obtain a branching ratio BR(B0→D−e+ν)=BR(B0→D−μ+ν)=(1.8±0.6±0.5)%.

Using the ARGUS detector at the DORIS II e+e− storage ring we have measured direct photons from the decay ???(1S)→γgg. The ratio Rγ=Γ(???(1S)→γgg)/Γ(???(1S)→ggg)=(3.00±0.13±0.18)% has been determined, from which we deduce values of the strong coupling constant αs=0.225±0.011±0.019 and the QCD scale parameter ΛMS=115±17±28 MeV defined in the modified minimal-subtraction scheme. The shape of the measured spectrum clearly rules out the predictions of the lowest order QCD calculations.

The reaction γγ→ϱ+ϱ−→π+π−π0π0 has been studied with the ARGUS detector at the e+e− storage ring DORIS II at DESY. Near threshold, the cross section for this reaction is about four times smaller than for the reaction γγ→ϱ0ϱ0.

The Large Hadron Collider (LHC) will be upgraded to Highluminosity LHC, increasing the number of simultaneous proton-proton collisions (pileup, PU) by several-folds. The harsher PU conditions lead to exponentially increasing combinatorics in charged particle tracking, placing a large demand on the computing resources. The projection on required computing resources exceeds the computing budget with the current algorithms running on single-thread CPUs. Motivated by the rise of heterogeneous computing in high-performance computing centers, we present Line Segment Tracking (LST), a highly parallelizeable algorithm that can run efficiently on GPUs and is being integrated to the CMS experiment central software. The usage of Alpaka framework for the algorithm implementation allows better portability of the code to run on different types of commercial parallel processors allowing flexibility on which processors to purchase for the experiment in the future. To verify a similar computational performance with a native solution, the Alpaka implementation is compared with a CUDA one on a NVIDIA Tesla V100 GPU. The algorithm creates short track segments in parallel, and progressively form higher level objects by linking segments that are consistent with genuine physics track hypothesis. The computing and physics performance are on par with the latest, multi-CPU versions of existing CMS tracking algorithms.

Results on hyperon production are reported for data accumulated at 10 GeV centre-of-mass energy with the ARGUS detector. Signals for both the octet states Λ, Σ0 and Ξ− and the decuplet states Σ± (1385), Ξ0 (1530) and Ω− are observed 1 (references to a specific state are to be interpreted as also implying the charge conjugate state), some for the first time in e+e− annihilation. Baryon rates from γdir (1S) decays are enhanced by a factor of about 3 over the continuum.

We report the first direct observation of B meson decays into Λc+ baryons using the decay channel Λc+ → pK−π+. The product of branching ratios Br(B→Λc+X)·Br(Λc+→pK−π+ = (0.30±0.12±0.06)% is derived from an observed signal of 208±89 events. Using previous measurements of inclusive baryon rates we find a branching ratio for Λc+ → pK−π+ of (4.1±2.4)%. The measured Λc+ momentum spectrum indicates that the multi-particle final states dominate the decay B→Λc+X.

Using the ARGUS detector at the DORIS II storage ring, we have observed the charmed baryons Σc++ and Σc0, through their decays to Λc+π±. We have measured the mean Σc−Λc+ mass difference as 167.6±0.3±1.6 MeV/c2. The isospin mass splitting between the Σc++ and the Σc0 was found to be 1.2±0.7±0.3 MeV/c2. The rate of Λc+ production from Σc decays was found to be (36±12±11)% of the total rate of Λc+ production. The Σc χp spectrum was observed to be similar to that of the Λc+, with a Peterson function parameter ϵ of 0.29±0.06.

The reaction γγ → 2π+2π−π0 has been studied using the the ARGUS detector at the e+e− storage ring DORIS II at DESY. The production of the vector-meson pair ωϱ0 is observed for the first time. The cross section for γγ → ωϱ0 and the topological cross section for γγ → 2π+2π−π0 are given. The angular distribution in ωϱ0 events do not indicate any specific dominant spin-parity; they are consistent with isotropic production and decay of the ω and ϱ0 mesons over the available Wγγ range.

The final state K +K−π+π− has been studied in γγ interactions using the ARGUS detector at the e+e− storage ring DORIS II at DESY. Production of the vector meson pair K∗0(892)K∗0(892) is observed for the first time. The cross section for K+K− π+π−, K∗0K−π++c.c. and K∗0K∗0 are all found to be of the order of a few nb. In the Wγγ range accessible, a mean upper limit of 0.5 nb at 95% CL is derived for φϱ0 production.

A search for two exotic decay modes of the ϒ(1S) meson has been made using the ARGUS detector at the e+e− storage ring DORIS II at DESY. The first was ϒ(1S) decays into weakly interacting particles, for which an upper limit of 2.3% at the 90% CL on the branching ratio is found. The second mode was ϒ(1S)→γa, where a is a neutral particle with mass less than 1.5GeV/c2, that either decays inside the detector or is sufficiently long-lived to escape detection. For short-lived particles a decaying into an e+e− pair, upper limits on the BR(ϒ(1S)→γa) of 3.1 × 10− at the 90% CL are found. The upper limit without restriction on the lifetime of a is found to be 1.3 × 10−3. Limits for other decay modes are also given.

The production of the pseudoscalar meson η'(958) is observed in the reaction e+e−→ e+e−η′→e+e−π+π−γ with the ARGUS detector at DESY. We measure the product Γγγ(η')Br(η′ →ϱγ) to be 1.13±0.04±0.13 keV. Using the known branching ratio s, we calculate Γγγ(η′) to be 3.76±0.13±0.47 keV and Γη' to be 203±32 keV.

Fireworks is a CMS event display which is specialized for the physics studies case. This specialization allows us to use a stylized rather than 3D-accurate representation when appropriate. Data handling is greatly simplified by using only reconstructed information and ideal geometry. Fireworks provides an easy-to-use interface which allows a physicist to concentrate only on the data in which he is interested. Data is presented via graphical and textual views. Fireworks is built using the Eve subsystem of the CERN ROOT project and CMS's FWLite project. The FWLite project was part of CMS's recent code redesign which separates data classes into libraries separate from algorithms producing the data and uses ROOT directly for C++ object storage, thereby allowing the data classes to be used directly in ROOT.

The reaction γγ → 2π+ 2π− 2π0 has been studied using the ARGUS detector at the e+e− storage ring DORIS II at DESY. Production of ω mesons is observed and, in particular, the reaction γγ → ωω is seen for the first time. The cross section for γγ → ωω has an enhancement at ∼ 1.9 GeV/c2 of about 10 nb. The cross sections for γγ → 2π+ 2π− 2π0 and γγ → ωπ+ π− π0 are also given.

We have searched for neutrinoless tau decays into three charged particles as evidence for lepton-flavour or lepton-number violation. The data were collected using the ARGUS detector at the DORIS II storage ring. Tau pairs were produced by e+e− annhilation at centre-of-mass energies near 10 GeV. No evidence for lepton-number or lepton-flavour violation was observed, but the upper limits obtained are an order of magnitude lower than those previously published.

Using the ARGUS detector at DORIS II, the decay of F+→K∗0K+, and the ratio BR(F+→K∗0K+)/BR(F+→ φπ+) is found to be 1.44±0.37. This is a substantial rate for a decay channel which cannot proceed via a colour-favoured diagram.

Using the ARGUS detector at the e+e− storage ring DORIS II at DESY, a search for the decays B→K∗γ has been made. The following upper limits were derived at 90% CL: BR(B→K∗(892)γ)<2.4×10−4, BR(B→K1(1400)γ)<4. −4, BR(B→K2∗(1430)γ)<8.3×10−4 and BR(B→K3∗ (1780)γ)<3.0×10−3.

The final states KS0KS0π+π− and KS0K∓ π0π±, produced in two-photon reactions, have been studied using the ARGUS detector at the e+e− storage ring DORIS II at DESY. The reaction γγ→K∗+K∗− has been observed for the first time. Its cross section is about eight times larger than that for γγ→K∗0K∗0, but it has a similar Wγγ dependence.

Using the ARGUS detector at the electron-positron storage ring DORIS II at DESY, we have measured the lifetime of the τ lepton to be (2.95±0.14±0.11)×10−13s.

Using the ARGUS detector at the e+ e− storage ring DORIS II, we have observed inclusive DS production, using the channel DS− → φπ−, in decays of B mesons produced on the ϒ(4S). The product of branching ratios BR(B→DSX)·BR(DS−→φπ−) is (4.2±0.9±0.6) × 10−3. The DS momentum spectrum suggests a substantial two-body component to the final states of B→DSX decays.

We have searched for the decay D+s→ρ0π+ which can only occur via annihilation of the constituent quarks, and compared it to the decay D+s→ρπ+ where the charm quark may decay independently of the light quark. An upper limit on the ratio BR(D+s→ρ0π+)BR(D+s→ρπ+) of 0.22 at the 90% confidence level is obtained. This result constra ins models which enhance. the weak annihilation contribution to heavy meson decays by final-state interactions, a mechanism used for explaining the large branching ratio observed for D0→ρK0.

One of the most computationally challenging problems expected for the High-Luminosity Large Hadron Collider (HL-LHC) is determining the trajectory of charged particles during event reconstruction. Algorithms used at the LHC today rely on Kalman filtering, which builds physical trajectories incrementally while incorporating material effects and error estimation. Recognizing the need for faster computational throughput, we have adapted Kalman-filter-based methods for highly parallel, many-core SIMD architectures that are now prevalent in high-performance hardware. In this paper, we discuss the design and performance of the improved tracking algorithm, referred to as MKFIT. A key piece of the algorithm is the MATRIPLEX library, containing dedicated code to optimally vectorize operations on small matrices. The physics performance of the MKFIT algorithm is comparable to the nominal CMS tracking algorithm when reconstructing tracks from simulated proton-proton collisions within the CMS detector. We study the scaling of the algorithm as a function of the parallel resources utilized and find large speedups both from vectorization and multi-threading. MKFIT achieves a speedup of a factor of 6 compared to the nominal algorithm when run in a single-threaded application within the CMS software framework.

We have searched for the lepton flavour-violating decay D0→μ±e∓ and for the rate decays D0μ+μ−, e+e− detector at the e+e− storage ring DORIS II. No candidates were found, leading to the upper limits BR (D0→μ+μ−)<7×10 − BR (D0→e+−)<1.7 × 10−4, and BR (D0→μ±e-+)<1.0 × 10−4 at 90 % confidence level.

Using the ARGUS detector at DORIS, we observe the production of D∗+s mesons in e+e− annihilation through their subsequent decays to a D+s and a photon. Photons which convert in the beam pipe or drift chamber inner wall are used to obtain a high precision measurement of the D∗+s-D+s mass difference, while photons detected in the shower counters are used to determine the production cross section, and to provide an independent measurement of the D∗+s-D+s mass difference. The observed D∗+s- D+s mass difference is 142.5±0.8±1.5 MeV/c2, and σ(e+e−→D∗+sX)·BR(D∗+s→D+sγ)(·BR(D+s→φπ+) is 4.4±1.1±1.0 pb at 10.2 GeV. The width of the D∗+s is less than 4.5 MeV/c2 at 90% confidence level.

The reaction γγ→K+K−π+π−π0 has been observed for the first time, using the ARGUS detector at the e+e− storage ring DORIS II at DESY. The cross section shows an enhancement for Wγγ close to 3 GeV/c2. Searches for γγ→ωφ and for γγ→φφ leading to this final state, as well as for γγ→φφ→2K+2K−, have been performed. The derived upper limits for ωφ and φφ production are compatible with qqqq model predictions.

We report the first observation of an orbitally excited baryon, the Λ(1520), in quark and gluon fragmentation. The production rate is found to be (1.15±0.21±0.16)×10−2 and (0.80±0.17−0.13+0.10)×10−2Λ(1520) hyperons per event in direct ϒ decays and in the continuum, respectively. In contrast to the observed situation for ground state baryons, the production of the Λ(1520) in direct ϒ decays shows little or no enhancement with respect to continuum production.

We have searched for D0−D̄0 mixing in the cascade decay of D∗+, using the excellent particle identification of the ARGUS detector. No mixing was observed, leading to an upper limit of 1.4% (90%CL) for Γ(D0 → D̄0→X′)Γ(D0→ X).

We have searched for the decay τ− → vτηπ− using data accumulated by the ARGUS detector at the e+e− storage ring DORIS II at DESY. No η signal was found in the π+π−π0 subsystems of the decay τ− →vτπ−π−π+ π0. We obtain an upper limit for the branching ratio of the decay τ− → vτηπ− of 1.3% at the 95% confidence level.

The decays B→Dπ− and B→Dϱ− are observed in data taken by the ARGUS detector at DORIS II. The measured branching ratios of the decays B−→D0π− and B0→D+ϱ− are (2.1±0.8±0.9)% and (2.2±1.2±0.9)% respectively, while those of the decays B−→D0π− and B0→D+π− are (0.19±0.10±0.06)% and (0.31±0.13±0.10)% respectively.

One of the most challenging computational problems in the Run 3 of the Large Hadron Collider (LHC) and more so in the High-Luminosity LHC (HL-LHC) is expected to be finding and fitting charged-particle tracks during event reconstruction. The methods used so far at the LHC and in particular at the CMS experiment are based on the Kalman filter technique. Such methods have shown to be robust and to provide good physics performance, both in the trigger and offline. In order to improve computational performance, we explored Kalman-filter-based methods for track finding and fitting, adapted for many-core SIMD architectures. This adapted Kalman-filter-based software, called "mkFit", was shown to provide a significant speedup compared to the traditional algorithm, thanks to its parallelized and vectorized implementation. The mkFit software was recently integrated into the offline CMS software framework, in view of its exploitation during the Run 3 of the LHC. At the start of the LHC Run 3, mkFit will be used for track finding in a subset of the CMS offline track reconstruction iterations, allowing for significant improvements over the existing framework in terms of computational performance, while retaining comparable physics performance. The performance of the CMS track reconstruction using mkFit at the start of the LHC Run 3 is presented, together with prospects of further improvement in the upcoming years of data taking.

One of the most computationally challenging problems expected for the High-Luminosity Large Hadron Collider (HL-LHC) is finding and fitting particle tracks during event reconstruction. Algorithms used at the LHC today rely on Kalman filtering, which builds physical trajectories incrementally while incorporating material effects and error estimation. Recognizing the need for faster computational throughput, we have adapted Kalman-filterbased methods for highly parallel, many-core SIMD and SIMT architectures that are now prevalent in high-performance hardware. Previously we observed significant parallel speedups, with physics performance comparable to CMS standard tracking, on Intel Xeon, Intel Xeon Phi, and (to a limited extent) NVIDIA GPUs. While early tests were based on artificial events occurring inside an idealized barrel detector, we showed subsequently that our mkFit software builds tracks successfully from complex simulated events (including detector pileup) occurring inside a geometrically accurate representation of the CMS-2017 tracker. Here, we report on advances in both the computational and physics performance of mkFit, as well as progress toward integration with CMS production software. Recently we have improved the overall efficiency of the algorithm by preserving short track candidates at a relatively early stage rather than attempting to extend them over many layers. Moreover, mkFit formerly produced an excess of duplicate tracks; these are now explicitly removed in an additional processing step. We demonstrate that with these enhancements, mkFit becomes a suitable choice for the first iteration of CMS tracking, and eventually for later iterations as well. We plan to test this capability in the CMS High Level Trigger during Run 3 of the LHC, with an ultimate goal of using it in both the CMS HLT and offline reconstruction for the HL-LHC CMS tracker.

Using the ARGUS detector at the e+e− storage ring DORIS II at DESY, we have measured the lifetimes of the D0, D+ and D+S mesons. We find τD0 = (4.8±0.4±0.3) × 10−13 s, τD+ = (10.5±0.8±0.7) × 10−13 s and τD +S = (5.6+1.3−1.2±0.8) × 10−13 s.

In this paper we present the features and the expected performance of the re-designed CMS simulation software, as well as the experience from the migration process. Today, the CMS simulation suite is based on the two principal components - Geant4 detector simulation toolkit and the new CMS offline Framework and Event Data Model. The simulation chain includes event generation, detector simulation, and digitization steps. With Geant4, we employ the full set of electromagnetic and hadronic physics processes and detailed particle tracking in the 4 Tesla magnetic field. The Framework provides "action on demand" mechanisms, to allow users to load dynamically the desired modules and to configure and tune the final application at the run time. The simulation suite is used to model the complete central CMS detector (over 1 million of geometrical volumes) and the forward systems, such as Castor calorimeter and Zero Degree Calorimeter, the Totem telescopes, Roman Pots, and the Luminosity Monitor. The designs also previews the use of the electromagnetic and hadronic showers parametrization, instead of full modelling of high energy particles passage through a complex hierarchy of volumes and materials, allowing significant gain in speed while tuning the simulation to test beam and collider data. Physics simulation has been extensively validated by comparison with test beam data and previous simulation results. The redesigned and upgraded simulation software was exercised for performance and robustness tests. It went into Production in July 2006, running in the US and EU grids, and has since delivered about 60 millions of events.

The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will produce particle collisions with up to 200 simultaneous proton-proton interactions. These unprecedented conditions will create a combinatorial complexity for charged-particle track reconstruction that demands a computational cost that is expected to surpass the projected computing budget using conventional CPUs. Motivated by this and taking into account the prevalence of heterogeneous computing in cutting-edge High Performance Computing centers, we propose an efficient, fast and highly parallelizable bottom-up approach to track reconstruction for the HL-LHC, along with an associated implementation on GPUs, in the context of the Phase 2 CMS outer tracker. Our algorithm, called Segment Linking (or Line Segment Tracking), takes advantage of localized track stub creation, combining individual stubs to progressively form higher level objects that are subject to kinematical and geometrical requirements compatible with genuine physics tracks. The local nature of the algorithm makes it ideal for parallelization under the Single Instruction, Multiple Data paradigm, as hundreds of objects can be built simultaneously. The computing and physics performance of the algorithm has been tested on an NVIDIA Tesla V100 GPU, already yielding efficiency and timing measurements that are on par with the latest, multi-CPU versions of existing CMS tracking algorithms.

The CMS object oriented Geant4-based program is used to simulate the complete central CMS detector (over 1 million geometrical volumes) and the forward systems such as the Totem telescopes, Castor calorimeter, zero degree calorimeter, Roman pots, and the luminosity monitor. The simulation utilizes the full set of electromagnetic and hadronic physics processes provided by Geant4 and detailed particle tracking in the 4 tesla magnetic field. Electromagnetic shower parameterization can be used instead of full tracking of high-energy electrons and positrons, allowing significant gains in speed without detrimental precision losses. The simulation physics has been validated by comparisons with test beam data and previous simulation results. The system has been in production for almost two years and has delivered over 100 million events for various LHC physics channels. Productions are run on the US and EU grids at a rate of 3-5 million events per month. At the same time, the simulation has evolved to fulfill emerging requirements for new physics simulations, including very large heavy ion events and a variety of SUSY scenarios. The software has also undergone major technical upgrades. The framework and core services have been ported to the new CMS offline software architecture and event data model. In parallel, the program is subjected to ever more stringent quality assurance procedures, including a recently commissioned automated physics validation suite

We present results from parallelizing the unpacking and clustering steps of the raw data from the silicon strip modules for reconstruction of charged particle tracks. Throughput is further improved by concurrently processing multiple events using nested OpenMP parallelism on CPU or CUDA streams on GPU. The new implementation along with earlier work in developing a parallelized and vectorized implementation of the combinatoric Kalman filter algorithm has enabled efficient global reconstruction of the entire event on modern computer architectures. We demonstrate the performance of the new implementation on Intel Xeon and NVIDIA GPU architectures.

During the 1988/1989 run at the Fermilab Tevatron, the CDF detector collected {approx equal}4.1 pb{sup {minus}1} of p{bar p} data at {radical}s = 1.8 TeV. The main goals of this run being physics at high p{sub t}, the CDF trigger was tuned'' for maximizing signals from Z{sup 0}s, Ws, t-quarks, etc. As such, compared to the high p{sub t} physics, the b-physics program was of secondary importance other than that which would be used for background calculations. Also, CDF had no vertex chamber capability for seeing displaced vertices. However, significant b-quark, physics results are evident in two data samples; inclusive electrons and inclusive J/{psi} where J/{psi} {yields} {mu}{sup +}{mu}{sup {minus}}. We can then ask ourselves, given all this, why is it that CDF is able to do b-quark physics The answer is that nature has been kind enough to provide b-quarks at an extremely high rate at the Tevatron. The production cross-section for b{bar b} production is quite large. In the rest of this paper, I will try to specify the goals for b-physics using the inclusive electrons and J/{psi} signals for the 1988/1989 data set. I will then provide a brief look at the data, and will finish withmore » some highly speculative guesses as to whether or not experiments at the Tevatron which look for CP violation in the b sector are possible.« less

After a hiatus of 3 years, CDF is again taking data. Many of the upgrades made to the detector during this period are described here, along with some preliminary indications of their performance. A brief survey of the new data is presented. Prospects for the current run are discussed.