The energy measurement of jets produced by b-quarks at hadron colliders suffers from biases due to the peculiarities of the hadronization and decay of the originating B hadron. The impact of these effects can be estimated by reconstructing the mass of Z boson decays into pairs of b-quark jets. From a sample of 584 pb-1 of data collected by the CDF experiment in 1.96 TeV proton-antiproton collisions at the Tevatron collider, we show how the Z signal can be identified and measured. Using the reconstructed mass of Z candidates we determine a jet energy scale factor for b-quark jets with a precision better than 2%. This measurement allows a reduction of one of the dominant source of uncertainty in analyses based on high transverse momentum b-quark jets. We also determine, as a cross-check of our analysis, the Z boson cross section in hadronic collisions using the b-bbar final state as sigma x B(Z->b-bbar) = 1578 +636 -410 pb.
We combine results from CDF and DO on direct searches for a standard model (SM) Higgs boson (H) in pbar-p collisions at the Fermilab Tevatron at sqrt{s}=1.96 TeV. Compared to the previous Higgs Tevatron combination, more data and new channels (WH to tau nu b bbar, VH to tau tau b bbar/jj tau tau, VH to jj b bbar, t tbar H to t tbar b bbar) have been added. Most previously used channels have been reanalyzed to gain sensitivity. We use the latest parton distribution functions and gg to H theoretical cross sections when comparing our limits to the SM predictions. With 2.0-3.6fb^-1 of data analyze…
The phenomenology of b-production and some of the previous Run I measurements of CDF and D0 are briefly reviewed. A new analysis by CDF of Run I b-bbar angular correlations and a new measurement by D0 of Run II b-jet cross-section, are presented.
In the top quark pair production in association with the Higgs boson decaying to a b quark pair t-tbar H (b-bbar), the final state has an irreducible nonresonant background from the production of a top quark pair in association with a b quark pair t-tbar b-bbar. Therefore, understanding of the t-tbar b-bbar process precisely in particular differential cross-section as functions of the properties of the additional b jets not from the top quark decay is essential for improving the sensitivity of a search for the t-tbar H b-bbar process. The two additional b jets can be identified by using variou…
We present a preliminary measurement of the rate of gluon splitting into bottom quarks, g -> b bbar, in hadronic Z0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavour. 4-jet events were identified, and a topological vertex-mass technique was applied to each jet in order to identify b or bbar jets. The upgraded CCD based vertex detector gives very high B-tagging efficiency, especially for B hadrons of the low energies typical of this process. The two most nearly collinear b/bbar jets were ta…
We have measured gluon splitting into bottom quarks, g -> b bbar, in hadronic Z0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavor. 4-jet events were identified, and in each event a topological vertex-mass technique was applied to the two jets closest in angle in order to identify them as b or bbar jets. The upgraded CCD vertex detector gives very high B-tagging efficiency, especially for B hadrons with the low energies typical of this process. We measured the rate of g -> b bbar production…
We study the discovery reach of the Tevatron and the LHC for detecting a Higgs boson (h), predicted in composite models of the electroweak symmetry breaking or in supersymmetric theories, with an enhanced b-quark Yukawa coupling via p \bar{p} / p p \to b \bbar h (\to b \bbar) + X. Our analysis shows that studying this process at the Tevatron Run II or the LHC can provide strong constraints on these models.
We present measurements of the b-bbar production cross section and angular correlations using the D0 detector at the Fermilab Tevatron p-pbar Collider operating at sqrt(s) = 1.8 TeV. The b quark production cross section for |y(b)|<1.0 and p_T(b)>6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and bbar quarks, measured from the azimuthal opening angle between their decay muons, also ag…
We study in this paper the production, in hadronic collisions, of final states with W gauge bosons, heavy quark pairs and n extra jets (with n up to 4). The complete partonic tree-level QCD matrix elements are evaluated using the ALPHA algorithm, and the events generated at the parton level are then evolved through the QCD shower and eventually hadronised using the coherent shower evolution provided by the HERWIG Monte Carlo. We discuss the details of our Monte Carlo implementation, and present results of phenomenological interest for the Tevatron Collider and for the LHC. We also comment on t…
Heavy quark production probes QCD at the interface of the perturbative and non-perturbative regimes. Studying the production of heavy quarks is an important test of models in both regimes. In this article, recent results on beauty and charm production from the CDF and D0 experiments at the Tevatron are reported. These include measurements of correlated b-bbar production, the psi(2S) production cross section, and Upsilon(1S) and Upsilon(2S) polarization.
The associated production of jets and vector bosons is an important process at hadron colliders. An overview over recent Tevatron vector boson+jets measurements is given with an emphasis on comparisons between data and the predictions of various theory models.
We combine results from CDF and D0 on direct searches for a standard model (SM) Higgs boson (H) in ppbar collisions at the Fermilab Tevatron at sqrt{s}=1.96 TeV. Compared to the previous Higgs Tevatron combination, more data and new channels (WH to tau nu b bbar, VH to tau tau b bbar/jj tau tau,VH to jj b bbar, t tbar H to t tbar b bbar) have been added. Most previously used channels have been reanalyzed to gain sensitivity. We use the latest parton distribution functions and gg to H theoretical cross sections when comparing our limits to the SM predictions. With 2.0-3.6 fb-1 of data analyzed …
We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into b bbar using the data sample collected with the D0 detector in p pbar collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% CL upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV <= M_H <= 150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% CL. In the mass range 120 GeV <= M_H <= 145 GeV the data exhibit an excess above the backgr…
I review here the latest measurements related to vector boson production in association with light or heavy flavor jets at the Tevatron and at the LHC. The methods to estimate the W+jets and Z+jets background in top-quark analyses are also presented.
We search for the technicolor process ppbar -> rho_T/omega_T ->W+pi_T in events containing one electron and two jets, in data corresponding to an integrated luminosity of 390 pb-1, recorded by the D0 experiment at the Fermilab Tevatron. Technicolor predicts that technipions, pi_T, decay dominantly into b-bbar, b-cbar, or bbar-c, depending on their charge. In these events b and c quarks are identified by their secondary decay vertices within jets. Two analysis methods based on topological variables are presented. Since no excess above the standard model prediction was found, the result is prese…
Studies of the production of W/Z + jets are important for a variety of reasons. W/Z + inclusive jets is a valuable high statistics sample that allows one to probe the validity of predictions from perturbative Quantum Chromodynamics (pQCD) at both leading and next-to-leading order. W/Z + heavy flavor jets (those originating from b or c production) is a significant background to top and Higgs at the Tevatron and will play an important role at the LHC as well. Herein the latest Tevatron results on these production mechanisms are reviewed with an emphasis on comparison of data results to the lates…
Collider signatures containing bosons and jets are particularly interesting. Recent theoretical effort has been devoted to determining predictions of W/Z + multiple parton production; the high statistics sample of W/Z + jets events collected at the Tevatron is a valuable testbed for probing the validity of these calculations. The final state containing a Z or W boson and one or more b-jets is a promising Higgs search channel at the Tevatron and could be a window to new physics at the LHC. These searches benefit from a deep understanding of the production of W/Z + heavy flavor jets which consti…
Recent results on diffractive dijet and vector boson production and exclusive dijet production from the Collider Detector at Fermilab (CDF) experiment are presented.
We present preliminary measurements of $Z/γ^*$+jets, $W+c$ and $Z+b+X$ at the Tevatron, and review recent measurements of vector boson plus inclusive and heavy-flavor jets production. All measurements are in agreement with next-to-leading-order QCD calculations within the experimental and theoretical uncertainties. We also point to comparisons of the production rate and kinematics of the data with several Monte Carlo simulation programs of vector boson + jets processes.
We present the most recent W and Z production, asymmetries, and V+jets results from the Tevatron collider at sqrt(s) = 1.96 TeV, analyzing data collected by CDF and DZero detectors between 2002-2011. The results include the measurements of the W and Z bosons properties, include boson p_T and asymmetries measurements, and also the W and Z boson plus jets productions. Those measurements provide the precision tests on the electroweak in Standard Model (SM), and high order theoretical predictions.
The structure of e+e- -> b bbar g events was studied using Z0 decays recorded in the SLD experiment at SLAC. Three-jet final states were selected and the CCD-based vertex detector was used to identify two of the jets as b or bbar. Distributions of the gluon energy and polar angle were measured over the full kinematic range for the first time, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous b chromomagnetic moment kappa. We measured kappa to be consistent with zero and set the first limits on its value, -0.17 < kappa < 0.11 at 95%…
Recent results from HERA and TevaTron on precision tests of QCD with jets, W and Z bosons and photons associated with jets and heavy flavours are presented. The measurements were used to probe QCD at the highest energies, to provide experimental constraints on SM processes that constitute background to new physics, to extract values of the coupling of the strong interaction and to constrain the proton parton distribution functions. The implications of the results on LHC physics are discussed.
Neural networks (NNs) provide a powerful and flexible tool for selecting a signal from a larger background. The D0 collaboration has used them extensively in studying t-tbar decays. NNs were essential to the measurement of the t-tbar production cross section in the all-jets channel (t tbar -> b bbar qqqq, and were also used in the measurement of the mass of the top quark in the lepton+jets channel (t tbar -> b bbar l nu q qbar). This paper will describe two new applications of neural networks to top~quark analysis: the search for single top~quark production, and an effort to increase the sensi…
The structure of e+e- -> bbg events was studied using Z0 decays recorded in the SLD experiment at SLAC. Three-jet final states were selected and the CCD-based vertex detector was used to identify two of the jets as b or bbar. Distributions of the gluon energy and polar angle were measured over the full kinematic range, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous b chromomagnetic moment kappa. We measured kappa to be consistent with zero and set limits on its value, -0.11 < kappa < 0.08 at 95% c.l. (preliminary).
The CDF and D0 collaborations performed a comprehensive study of the production of vector bosons, W and Z, in association with energetic jets. Understanding the W/Z + jets and W/Z + c, b-jets processes is of paramount importance for the top quark physics, for the Higgs boson measurements, and for many new physics searches. In this contribution the most recent measurements of the associated production of jets and vector bosons in Run II at the Tevatron are presented. The measurements are compared to different perturbative QCD predictions and to several Monte Carlo generators.
Results are presented from four CDF analyses involving heavy quark production in proton-antiproton collisions at center of mass energy 1.96 TeV. The shapes of b-jets are found to be broader than inclusive predictions and broader than both PYTHIA and HERWIG defaults. A measurement of the production cross section for psi(2S) is consistent with Run 1 results and with theoretical predictions associated with parton distribution function energy dependence. The inclusive b-jet production cross section is also consistent with theoretical predictions over six orders of magnitude. The b-bbar differentia…
We report on recent Z (+jets) measurements from the Fermilab Tevatron proton anti-proton collider. A new D0 measurement of the transverse momentum of Z bosons yields the best measurement to date of the non-perturbative form factor, g2. The production of Z+jets is an major background to many rare signals, and is a vital testing ground for theoretical predictions. Measurements from CDF and D0 of differential cross sections in Z+jet production test NLO pQCD, and in the case of D0, the latest tree-level matrix element with matched parton shower calculations. Improving modelling of this signal will…
Measurements of the inclusive jet cross section and the dijet angular distribution using data from the Tevatron are presented. Comparisons to NLO QCD show good agreement below 250 GeV, but CDF data show an excess at higher ET; qualitative agreement is seen between the CDF and DO cross sections. Analysis of the dijet angular distributions exclude quark compositeness below 2.1 TeV.
The DØ and CDF experiments have each collected more than 8 fb-in Run II of Fermilab's Tevatron, and have many recent search results which use up to 5.2 fb-1 . Here I summarize the results of a variety of searches for physics beyond the Standard Model with an emphasis on searches for very exotic phenomena. I will present the status of model-inspired searches for several signatures of supersymmetry, as well as several other searches for several "hidden- valley" inspired models, all of which contain photons and jets in the final state.
Recent measurements on the vector boson plus heavy-flavor jets production by the CDF and D0 experiments are presented in comparisons with recent theoretical predictions. Good understanding of such processes is important to improve our understanding of QCD and also to enhance the potential to search for yet-to-be-discovered new physics phenomena which lead to similar final states.
Various measurements of the top quark mass in the lepton+jets decay channel of top quark pair production are presented. The measurements are performed on data samples of up to 2.7 fb-1 of integrated luminosity acquired by the CDF and D0 experiments in Run-II of the Tevatron proton-anti-proton collider at a center-of-mass energy of sqrt(s) = 1.96 TeV. The new Tevatron combination using up to 2.8 fb-1 of data results in a preliminary world average mass of the top quark of m_top = 172.4 +- 1.2 GeV. This corresponds to a relative precision of 0.7%.
The Fermilab Tevatron Collider is currently the most copious source of b-hadrons, thanks to the large b-bbar production cross-section in 1.96 TeV ppbar collisions. Recent detector upgrades allow for a wide range of CP violation and flavor-mixing measurements that are fully competitive (asymmetries in self-tagging modes) or complementary (asymmetries of B_s and b-baryons decays) with B-factories. In this paper we review some recent CP violation results from the DO and CDF Collaborations and we discuss the prospects for future measurements.
A comprehensive overview of the latest aspects of jet physics in proton-antiproton collisions at $\sqrt{s}=$1.96 TeV is presented. In particular, measurements of the inclusive jet production, dijet and multi-jet production, and jet substructure studies are discussed.
Latest jet results from the Tevatron are presented in this conference note. These are namely: new results on central inclusive jet production using both cone and $k_T$ algorithms, measurement of decorrelation in azimuthal angle between the two jets with the highest transverse momenta, and study of jet shapes. Results are based on data collected in $\mathrm{p}\bar{\mathrm{p}}$ collisions at $\sqrt{s}=1.96 \mathrm{TeV}$ in the years 2001-2004. Depending on the analysis, integrated luminosity of the sample was up to $378 \mathrm{pb}^{-1}$.
The structure of three-jet e+e- -> b bbar g events has been studied using hadronic Z0 decays recorded in the SLD experiment at SLAC. Three-jet final states were selected and the CCD-based vertex detector was used to identify two of the jets as b or bbar; the remaining jet in each event was tagged as the gluon jet. Distributions of the gluon energy and polar angle with respect to the electron beam were measured over the full kinematic range, and used to test the predictions of perturbative QCD. We find that beyond-leading-order QCD calculations are needed to reproduce the features seen in the d…
We present a measurement of the correlated $b\bar{b}$ production cross section. The data used in this analysis were taken with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider, and correspond to an integrated luminosity of 742 pb$^{-1}$. We utilize muon pairs with invariant mass $5 \leq m_{μμ} \leq 80 \gevcc$ produced by $b\bar{b}$ double semileptonic decays. For muons with $p_T \geq 3 \gevc$ and $|η| \leq 0.7$, that are produced by $b$ and $\bar{b}$ quarks with $p_T \geq 2 \gevc$ and $|y| \leq 1.3$, we measure $σ_{b\toμ,\bar{b}\to μ}= 1549 \pm 133$ pb. We compare this resu…
Results are presented for the inclusive jet cross section versus jet transverse energy in proton-antiproton collisions at center of mass energy 1.8 TeV as measured by the CDF and D0 detectors at Fermilab's Tevatron collider. The data are compared to next-to-leading order QCD predictions using different input parton distribution functions. The ratio of inclusive jet cross sections at center of mass energy 0.63 TeV and center of mass energy 1.8 TeV, versus jet x_T, is also presented and compared to QCD predictions.
Recent searches performed by the CDF and D0 collaborations at the Tevatron for diboson production in final states containing heavy-flavor jets are reported. The searches for WZ and ZZ can be regarded as the ultimate benchmark for the corresponding searches for a low-mass Higgs boson in the WH and ZH final states. Using the exact same techniques as for those Higgs boson searches, the D0 collaboration measured a cross section for WZ/ZZ production of 1.13 +/- 0.36 times its expectation in the standard model, with a diboson signal significance of 3.3 standard deviations (2.9 expected).
An overview of latest top quark pair production cross-sections measured at the Tevatron is given. These measurements have been carried out in the dilepton, lepton+jets and all-jets channels with an integrated luminosity of about 1fb-1. The measurements are consistent with NNLO calculations.
At the Fermilab Tevatron energies, ($\sqrt{s}$=1800 GeV and $\sqrt{s}$=630 GeV), jet production is the dominant process. During the period 1992-1996, the D0 and CDF experiments accumulated almost 100 pb**-1 of data and performed the most accurate jet production measurements up to this date. These measurements and the NLO-QCD theoretical predictions calculated during the last decade, have improved our understanding of QCD, our knowledge of the proton structure, and pushed the limit to the scale associated with quark compositeness to 2.4-2.7 TeV. In this paper, we present the most recent publish…
The latest results on the measurements of electroweak top-quark production at the Tevatron are presented with the full RunII dataset. The CDF and D0 Collaborations have performed measurements of the s, t, and s+t channels in both l+jets and MET+jets final states. Evidence for the production of the s channel is presented for the first time.
We review the use of Monte Carlo simulation to model backgrounds to top signal at the Tevatron experiments, CDF and D0, as well as the relevant measurements done by the experiments. We'll concentrate on the modeling of W and Z boson production in association with jets, in particular heavy flavor jets, and also comment on the Tevatron experience using matched Monte Carlo.
We present a summary of recent measurements of $W$ and $Z$ properties and $W/Z$ production in association with jets in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV with the CDF and DØ detectors. Latest measurements of $Z/γ^*$ transverse momentum and are presented along with new measurements of the angular distributions of final state electrons from Drell Yan events as a way to probe $Z$ boson production mechanisms. The mass dependence of the forward-backward asymmetry in $p\bar{p} \rightarrow Z/γ^{*} \rightarrow e^+e^-$ interactions is measured, the effective weak mixing angle extracted, and t…
The latest top quark mass measurements by the CDF and DØ~ experiments are presented here. The mass has been determined in the dilepton ($\ttbar \to eμ,ee,μμ$ + jets +$\met$) and lepton plus jets ($\ttbar \to e$ or $μ$ + jets +$\met$) final states. The most accurate single result from lepton plus jets channel is 173.5$^{+3.7}_{-3.6}$(stat. + Jet Energy Scale Systematic)$\pm1.3$(syst.) ~GeV/c$^{2}$, which is better than the combined CDF and DØ~ Run~I average. A preliminary and unofficial average of the best experimental Run~II results gives $M_{top}$ = $172.7\pm3.5$ GeV/c${^2}$.
We report a measurement of the fraction of top quark pair events produced via gluon-gluon fusion in $p\bar{p}$ collisions at $\sqrt{s} = 1.96 ~\rm TeV$ in lepton+jets final states using the full RunII data set corresponding to $9.7 ~\rm fb^{-1}$ of integrated luminosity collected by the DØ experiment. We utilize a boosted decision tree to distinguish top quark pair events produced by $q\bar{q}$ annihilation and $gg$ fusion. We perform a template fit to extract the $t\bar{t}$ production fraction via $gg$ fusion and find $f_{gg} = 0.096 \pm 0.039 ~(\rm stat.) ~^{+0.077}_{-0.062} ~(\rm syst.)$.
Jets have been used to verify the theory of quantum chromodynamics (QCD), measure the structure of the proton and to search for the physics beyond the Standard Model. In this article, we review the current status of jet physics at the Tevatron, a sqrt(s) = 1.96 TeV p-pbar collider at the Fermi National Accelerator Laboratory. We report on recent measurements of the inclusive jet production cross section and the results of searches for physics beyond the Standard Model using jets. Dijet production measurements are also reported.
We present a combination of measurements of the mass of the top quark, $m_{\rm top}$, performed by the CDF and D0 experiments at the Tevatron collider and the ATLAS and CMS experiments at the Large Hadron Collider (LHC). The Tevatron data correspond to an integrated luminosity of up to 8.7 fb${^{-1}}$ of proton-antiproton collisions from Run II of the Tevatron at a centre-of-mass energy of 1.96 TeV. The LHC data correspond to an integrated luminosity of up to 4.9 fb${^{-1}}$ of proton-proton collisions from the run at a centre-of-mass energy of 7 TeV. The combination includes measurements in t…
Recent measurements of selected QCD processes at the Tevatron are reviewed and confronted with theoretical calculations. Results on inclusive jet production at large transverse momentum are compared to predictions from next-to-leading order perturbative QCD. Kinematic distributions of jets with light and heavy flavor produced in association with electroweak bosons are compared to expectations from leading-order QCD calculations supplemented with parton-shower models. Properties of QCD radiation in hard-scatter events are investigated using azimuthal correlations between two leading jets in mul…
An overview of recent experimental searches for SUSY particles is presented. These searches are based on data collected by the CDF and the \D0 experiments operating at the Fermilab Tevatron proton-antiproton collider with $\sqrt{s}$ = 1.96 TeV. The review focuses on searches for squarks and gluinos in final states with missing transverse energy and jets. Emphasis will be given to the search for the gluino decaying into a sbottom and $b$ quark with each sbottom decaying into a $b$ quark and a neutralino. This scenario yields events containing 4 $b$-jets and missing transverse energy.
We review the measurements of the top quark mass by the CDF and D-Zero collaborations using Run I data in excess of 100 inverse picobarns. The D-Zero collaboration has recently updated its measurement of the top quark mass in the lepton + jets channel. The world average of the top quark mass from the CDF and D-Zero measurements in the lepton + jets channel now stands at 175.6 +/- 5.5 GeV/c**2.
We present measurements of the top-antitop production cross section in b-tagged lepton + jets events from proton-antiproton collisions at 1.96 TeV using the CDF detector at Fermilab. B-jets are tagged with either a secondary vertex algorithm, or a soft lepton tagger that identifies muons from B hadron semileptonic decays. With Tevatron Run II data, we estimate the top-antitop signal fraction in two different ways: by estimating the various background contributions, and by fitting directly the leading jet transverse energy spectrum for the signal and background contributions. A subset of the sa…
The production of single-top quarks occurs via the weak interaction at the Fermilab Tevatron proton-antiproton collider. Single top quark events are selected in the lepton+jets final state by CDF and D0 and in the missing transverse energy plus jets final state by CDF. Multivariate classifiers separate the s-channel and t-channel single-top signals from the large backgrounds. The combination of CDF and D0 results leads to the first observation of the s-channel mode of single top quark production. The t-channel and single top combined cross sections have also been measured.
This paper reports the most recent measurements of single top quark production performed by CDF and D0 collaborations in proton-antiproton collisions at Tevatron. Events are selected in the lepton+jets final state by CDF and D0 and in the missing transverse energy plus jets final state by CDF. The small single top signal in s-channel, t-channel and inclusive s+t channel is separated from the large background by using different multivariate techniques. We also present the most recent results on extraction of the CKM matrix element $|V_{tb}|$ from the single top quark cross section.
We measure the correlation between the spin of the top quark and the spin of the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96 TeV, where l is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and tbar rest frames, yielding a correlation strength C= 0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction withi…
We investigate the possibility that the W+4 jets background is a source of the anomalously large top-antitop (tt) charge asymmetry observed at the Tevatron. We simulate the tt reconstruction of the signal and background events at the matrix-element level and find that the reconstructed tt candidates from the W +4 jets background could give large forward-backward asymmetry. We suggest serious re-evaluation of the W+4 jets background for the tt candidate events by studying the distributions of the reconstructed tt systems in their rapidity difference, the transverse momentum of the top quark, an…
We present a search for neutral Higgs bosons decaying into b-bbar, produced in association with b quarks in p-pbar collisions. This process could be observable in supersymmetric models with high values of tan(beta). The event sample corresponds to 2.6/fb of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two lead jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the non-resonant mul…
The production of a Standard Model Higgs boson in association with a top quark pair at the upcoming high luminosity run (15 inverse fb integrated luminosity) of the Fermilab Tevatron (root s = 2.0 TeV) is revisited. For Higgs masses below 140 GeV we demonstrate that the production cross section times branching ratio for H->B Bbar decays yields a significant number of events and that this mode is competitive with and complementary to the searches using P Pbar -> WH, ZH associated production. For higher mass Higgs bosons the H -> W+ W- decays are more difficult but have the potential to provide …
How massive elementary particles get their mass is one of the greatest open questions in physics. Two of the major goals of the current LEP2 physics program that help to address this question are (a) to measure as precisely as possible the W Boson mass mW and (b) to exclude or discover the Higgs Boson within the available kinematic region. The reconstruction of invariant masses with jets from 4-jet channels (e.g. WW -> q qbar q qbar and HZ -> b bbar q qbar) and missing energy channels (e.g WW -> e nu q qbar and e+e- -> H nu nubar) is discussed. The emphasis is on the determination of mW, from …
Selected quantum chromodynamics measurements performed at the Fermilab Run II Tevatron ppbar collider running at sqrt{s}=1.96 TeV by D0 and CDF Collaborations are presented. Events with W/Z+jets productions are used to measure many kinematic distributions allowing extensive tests and tunes of predictions from perturbative QCD at next-to-leading order and Monte-Carlo event generators.
We summarize measurements of b and c jet production at the LHC, which are an important signature and background for decays of massive particles such as H-to-b-bbar. These include measurements of the inclusive and dijet production of heavy quark jets, b and c jets produced in association with vector bosons Z and W, and decays of boosted Z bosons into pairs of b-bbar. The current status of b tagging and b jet energy scale is also reviewed. These measurements test perturbative QCD in the four and five-flavor number schemes, and provide insight into the relative importance of heavy flavor producti…
We present a study of top quark polarization in $t \overline{t}$ events produced in $p \overline{p}$ collisions at $\sqrt{s}=1.96$ TeV. Data correspond to 9.7 fb$^{-1}$ collected with the D0 detector at the Tevatron. We use final states containing a lepton and at least three jets. The polarization is measured using the distribution of leptons along the beam and helicity axes, and the axis normal to the production plane. This is the first measurement of top quark polarization at the Tevatron in $\ell$+jets final states, and first measurement of transverse polarization in $t \overline{t}$ produc…
