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The 2019 European Physical Society Prize for High Energy and Particle Physics was awarded to the CDF and D0 collaborations for "the discovery of the top quark and the detailed measurement of its properties". This paper is based upon the talk accepting the prize on behalf of the D0 Collaboration.
Experimental results from the CDF and D0 Collaborations at the Tevatron and the ATLAS and CMS Collaborations at the LHC on the processes related to probing top quark couplings are presented. Evidence of both $t\bar{t}Z$ and $t\bar{t}W$ processes is reported. All measurements are in agreement with the SM expectations.
A review of the current experimental results on searches for Higgs bosons in models beyond the Standard Model is presented. Searches from ATLAS, CMS and LHCb use datasets from Run 1 of the LHC, including 7 and 8 TeV proton-proton collisions. Searches from CDF and D0 use the full or partial 1.96 TeV proton-anti-proton collision datasets from the Tevatron.
These proceedings report on a collection of Higgs boson property studies based on the LHC Run 1 dataset, consisting of about 25 fb$^{-1}$ pp collision data collected at a center-of-mass energy of 7 and 8 TeV by the ATLAS and CMS experiments at the Large Hadron Collider, as well as a study from the CDF and D0 experiments, based on about 10 fb$^{-1}$ $p \bar{p}$ collision data taken at a center-of-mass energy of 1.96 TeV at the Tevatron collider. The results of total, fiducial and differential cross section measurements are reported, and studies of the spin and parity are described. No significant deviation from the Standard Model predictions has been found. Searches for rare decay channels, including $H \rightarrow Z \gamma, H \rightarrow \mu \mu, H \rightarrow J/ \psi \gamma$ and $H \rightarrow \gamma^* \gamma \rightarrow \ell \ell \gamma $ do not show any evidence for signal and upper limits on their branching fractions are set.
An overview of searches for top quark flavour changing neutral currents (FCNC) from the CDF, D0, ATLAS and CMS collaborations is presented. The FCNC interactions of top quarks are probed through the anomalous decays and production channels. No clear evidence for the presence of the signal is observed in none of the searches and the upper limits are set at 95% confidence level (CL) on the cross sections, anomalous couplings and the branching ratios.
We present the most recent measurements of single top quark production cross section by the CDF and D0 experiments at the Fermilab Tevatron Collider and the ATLAS and CMS experiments at the Large Hadron Collider (LHC). The data were collected at the Tevatron corresponding to an integrated luminosity of up to 9.7 fb$^{-1}$ of proton-antiproton ($p\bar p$) collisions at a centre-of-mass energy of 1.96 TeV and at the LHC corresponding to an integrated luminosity of up to 4.9 fb$^{-1}$ of proton-proton ($pp$) collisions at a centre-of-mass energy of 7 TeV in 2011 and up to 20.3 fb$^{-1}$ at a centre-of-mass energy of 8 TeV in 2012. The measurements of single top quark production in $s$-channel, $t$-channel and associated production of a top quark and a $W$-boson ($tW$ production) are presented separately and lower limits on the CKM matrix element $|V_{tb}|$ from the single top quark cross section are set.
Successful operation of the Large Hadron Collider has led to more than 1 fb^-1 of data recorded with both ATLAS and CMS detectors by summer of 2011. This large amount of data has allowed to perform numerous searches for rare processes beyond the Standard Model, many of which are competitive with previous searches performed with the CDF and D0 detectors at the Tevatron. In this talk the most recent searches at the hadron colliders are reviewed.
A study of initial-state gluon radiation (ISR) in hadron collisions is presented using Drell-Yan (DY) events produced in proton-antiproton collisions by the Tevatron collider at a center-of-mass energy of 1.96 TeV. This paper adopts a novel approach which uses the mean value of the Z/$\gamma^*$ transverse momentum $ $ in DY events as a powerful observable to characterize the effect of ISR. In a data sample corresponding to an integrated luminosity of 9.4 fb$^{-1}$ collected with the CDF Run II detector, $ $ is measured as a function of the Z/$\gamma^*$ invariant mass. It is found that these two observables have a dependence, $ = -8 + 2.2 \ln m_{DY}^2$ [GeV/c], where $m_{DY}$ is the value of the Z/$\gamma^*$ mass measured in units of GeV/$c^2$. This linear dependence is observed for the first time in this analysis. It may be exploited to model the effect of ISR and constrain its impact in other processes.
I report on direct and indirect searches for new physics in top events from the CDF and D0 Collaborations at the Fermilab Tevatron Collider.
For almost a quarter of a century, the Tevatron proton-antiproton collider was the centerpiece of the world's high energy physics program - beginning operation in December of 1985 until it was overtaken by LHC in 2011. The aim of this unique scientific instrument was to explore the elementary particle physics reactions with center of mass collision energies of up to 1.96 TeV. The initial design luminosity of the Tevatron was 1030cm-2s-1, however as a result of two decades of upgrades, the accelerator has been able to deliver 430 times higher luminosities to each of two high luminosity experiments, CDF and D0. The Tevatron will be shut off September 30, 2011. The collider was arguably one of the most complex research instruments ever to reach the operation stage and is widely recognized for many technological breakthroughs and numerous physics discoveries. In this John Adams lecture, I briefly present the history of the Tevatron, major advances in accelerator physics, and technology implemented during the long quest for better and better performance. Lessons learned from our experience are also discussed.
We present a search for Higgs boson produced in the di-tau modes or via the associated $p\bar{p}\to h+b \to\tau^+\tau^-b$ process at a center-of-mass energy of $\sqrt{s}=$1.96 TeV using up to 1.8-7.3 fb$^{-1}$ of data collected with the D0 and CDF detector at the Fermilab Tevatron collider. In Supersymmetric models Higgs boson production cross section can be significantly enhanced compared to the Standard Model. Additionally the Higgs boson has a significant branching ratio to $\tau$ leptons at all masses. The di-$\tau$ and $b-\tau\tau$ channels complement each other providing best sensitivity for the search in the SUSY parameter space
Recent measurements of high E_T jet production at the Tevatron are presented. These data provide stringent tests of perturbative QCD as well as constraints on parton distribution functions, the strong coupling constant and models implemented in event generators. Measurements of inclusive jet and multijet production as well as the associated production of jets with the electroweak bosons obtained by both the D0 and CDF collaborations are reviewed.
We propose a particularly simple explanation of the W+dijet excess reported by the CDF collaboration. No symmetries beyond those of the standard model are necessary, and the only new particles involved are a spin-zero weak SU(2) doublet with no vacuum expectation value. Possible tests of the model and comparisons to other proposals are discussed.
According to Scientific and Technical Cooperation between the USA and Russia in the field of nuclear engineering the Idaho National Laboratory has transferred to the possession of the National Research Center ' Kurchatov Inst. ' the SAPHIRE software without any fee. With the help of the software Kurchatov Inst. developed a Pilot Living PSA- Model of Leningrad NPP Unit 1. Computations of core damage frequencies were carried out for additional Initiating Events. In the submitted paper such additional Initiating Events are fires in various compartments of the NPP. During the computations of each fire, structure of the PSA - Model was not changed, but Fault Trees for the appropriate systems, which are removed from service during the fire, were changed. It follows from the computations, that for ten fires Core Damaged Frequencies (CDF) are not changed. Other six fires will cause additional core damage. On the basis of the calculated results it is possible to determine a degree of importance of these fires and to establish sequence of performance of fire-prevention measures in various places of the NPP. (authors)
In this study, frameworks and methodologies for the development of technical basis of quantitative safety goals will be established. Most studies on the technical basis of the quantitative safety goals have been conducted after the commercial operations of NPPs. As a matter of fact, PSA insights are of much use for these kind of studies, hence it was not practical to provide the technical bases in a timely manner due to the unavailability of PSA studies at the moment. FANR has adopted the following mean values as quantitative safety goals: overall core damage frequency (CDF) < 10{sup -5}/ry and overall large release frequency (LRF) < 10{sup -6}/ry. Capabilities, framework, and methodologies to develop the technical basis of the quantitative safety goals in the UAE are established. Moreover, preliminary technical bases are developed in an early phase of NPP program in the UAE, which will lead to establishment, management, and update of the quantitative safety goals in a later phase.
The delayed-gamma (DG) line-emission (line) sampling was first introduced into MCNPX in 2005. At the time, storage demands for problems with large numbers of DG lines was a major concern. In order to accommodate large amounts of line data while keeping the memory footprint of such a problem from exceeding memory limits, complicated logic was included to sift through various storage options. In mid-2015 concerns arose over the adequacy of the MCNP6 DG source option (inherited from MCNPX) with line sampling for modeling high-fidelity problems. One indication that there was a problem came when studying the MCNP6 produced DG spectra of U-238 and its progeny using high-fidelity spectroscopic tallies when compared to DG line amplitudes directly from ENDF/B-VII.1 emission data. Despite producing a correct integral number of gammas, the comparison to ENDF data showed a broadening in the energy lines and a reduction in the amplitude of more prominent lines. It was later found that the cause of this broadening was one of the memory-saving techniques used to store DG line data when problems required many DG lines. Specifically, the DG lines were integrated into fine energy bins for sampling. When a DG line was to be sampled, a random number would be used to choose which energy bin to sample based on emission probability. Once chosen, a second random number was used to perform nearest-line sampling in that bin. The integration of lines led to an oversampling of low-probability lines, especially when in close proximity to high-probability lines. This treatment also caused a similar issue with the time-dependent behavior of DG line emission which occurred when low-probability lines were sampled near high probability lines with the former decay constant being used. The effect on time-dependent gamma production was demonstrated in analytic benchmarks performed by Weldon et al.. To address these issues a new gamma line storage and sampling treatment was introduced in 2015. This new treatment, stores gamma emission data in a line-by-line CDF which is sampled directly, thereby resolving both the line-broadening issue, and the time-dependence issue as was demonstrated by Tutt el al.. In addition, the new DG sampling treatment was written to use dynamically dimensioned storage arrays as opposed to large fixed-dimensioned arrays, as in the former treatment, and also makes more efficient use of line data that is stored by reducing or eliminating repeated data. As a result, storage arrays are generated only for DG data relevant to the problem being executed. The result should be a reduction in both memory requirements and runtime. However, these reductions could not be realized until the logic for the old treatment could be removed. This paper provides an update on recent work which has focused on the removal of the old DG sampling logic and attempts to quantify the memory reduction and speed up of selected problems.
A general review of the latest results about single and double vector boson production in the multipurpose experiments at LHC (ATLAS and CMS) and at Tevatron (CDF and D0) will be presented. The review will focus on boson production, while a more detailed report about W and Z properties can be found elsewhere. Only leptonic decays into electrons and muons will be considered.
In this paper we discuss the luminosity determination at the Tevatron. We discuss luminosity measurements by the machine as well as by using the luminosity detectors of the CDF and D0 experiments. We discuss the uncertainties of the measurements, the effort to maximize the initial and integrated luminosity, the challenges and the lessons learned.