First combination of Tevatron and LHC measurements of the top-quark mass

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 the $t\bar t\to$ lepton+jets, $t\bar t\to$ dilepton, $t\bar t\to$ all jets and $t\bar t\to$ $E_{\rm T}^{\rm miss}$+jets final states. The resulting combined measurement of $m_{\rm top}$ is 173.34 \pm 0.27 \mbox{(stat)} \pm 0.71 \mbox{(syst)} GeV, with a total uncertainty of $0.76$ GeV.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 the $t\bar t\to$ lepton+jets, $t\bar t\to$ dilepton, $t\bar t\to$ all jets and $t\bar t\to$ $E_{\rm T}^{\rm miss}$+jets final states. The resulting combined measurement of $m_{\rm top}$ is 173.34 \pm 0.27 \mbox{(stat)} \pm 0.71 \mbox{(syst)} GeV, with a total uncertainty of $0.76$ GeV

Procedure for the LHC Higgs boson search combination in Summer 2011

In this note, we report the results of the technical combination exercises conducted by the group during Winter-Spring 2011 and summarize the decisions taken in preparation for the statistical combination of the Standard Model Higgs boson searches at the LHC. The procedure to be used for the combination in Summer 2011 is explicitly detailed to avoid potential biases from decisions taken after the data have been collected

Higgs Search in bbˉb\bar{b} Signatures at ATLAS and CMS

We report on searches for the Standard Model Higgs boson decaying to $b \bar{b}$ in $pp$ collisions at the ATLAS and CMS experiments. These rely on signatures where the Higgs boson is produced in association with a vector boson or in association with a top-quark pair. Results are presented, based on $5.0~\mathrm{fb}^{-1}$ of $pp$ collision data at $\sqrt{s} = 7$~TeV and up to $13.0~\mathrm{fb}^{-1}$ of data at $\sqrt{s} = 8$~TeV collected by the LHC accelerator. These are expressed in terms of 95\% confidence level upper limits on the production cross section of the Standard Model Higgs boson times the branching ratio to decay to $b$-quark pair.We report on searches for the Standard Model Higgs boson decaying to $b \bar{b}$ in $pp$ collisions at the ATLAS and CMS experiments. These rely on signatures where the Higgs boson is produced in association with a vector boson or in association with a top-quark pair. Results are presented, based on $5.0~\mathrm{fb}^{-1}$ of $pp$ collision data at $\sqrt{s} = 7$~TeV and up to $13.0~\mathrm{fb}^{-1}$ of data at $\sqrt{s} = 8$~TeV collected by the LHC accelerator. These are expressed in terms of 95\% confidence level upper limits on the production cross section of the Standard Model Higgs boson times the branching ratio to decay to $b$-quark pair

Review of recent top-quark LHC combinations

A review of recent combinations of top-quark measurements performed at the LHC, by the ATLAS and CMS collaborations, is provided. The typical uncertainty categorisations, and their assumed correlation patterns are presented, together with the results of the combinations of the top-quark pair and single top-quark production cross sections, the top-quark mass, as well as of the $W$ boson polarisation and the charge asymmetry in $t\bar t$ events.A review of recent combinations of top-quark measurements performed at the LHC, by the ATLAS and CMS collaborations, is provided. The typical uncertainty categorisations, and their assumed correlation patterns are presented, together with the results of the combinations of the top-quark pair and single top-quark production cross sections, the top-quark mass, as well as of the $W$ boson polarisation and the charge asymmetry in $t\bar t$ events

The Voyage of Discovery of the Higgs Boson at the LHC

The journey in search for the Higgs boson started in earnest with the discovery of the W and Z bosons. The LHC accelerator, the ATLAS and CMS experiments were conceived in the late 1980s and early 1990s, and it took two decades to turn the concepts to reality. Novel and innovative technologies needed to be developed and turned into superbly functioning engines for providing proton-proton collisions in the case of the LHC and physics results in the case of the experiments. The most significant discovery so far to emerge from the LHC project is that of a heavy scalar boson, announced on 4th July 2012. The data collected so far point strongly to its properties as those expected for the Higgs boson associated with the Brout-Englert-Higgs mechanism

Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at sqrt(s) = 8 TeV

The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb 121 for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal (F0), left-handed (FL), or right-handed (FR) polarizations. The resulting combined measurements of the polarization fractions are F0 = 0.693 \ub1 0.014 and FL = 0.315 \ub1 0.011. The fraction FR is calculated from the unitarity constraint to be FR = 120.008 \ub1 0.007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F0 (FL) with respect to the most precise single measurement. A limit on anomalous right-handed vector (VR), and left- and right-handed tensor (gL, gR) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [ 120.11, 0.16] for VR, [ 120.08, 0.05] for gL, and [ 120.04, 0.02] for gR, at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived

Combinations of single-top-quark production cross-section measurements and |ƒ_LVV_tb| determinations at √s = 7 and 8 TeV with the ATLAS and CMS experiments

This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at s√ = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb⁻¹ at s√ = 7 TeV and 12.2 to 20.3 fb⁻¹ at s√ = 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 ± 5.7 pb and 87.7 ± 5.8 pb at s√ = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 ± 4.1 pb and 23.1 ± 3.6 pb at s√ = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 ± 1.4 pb at s√ = 8 TeV. The square of the magnitude of the CKM matrix element Vtb multiplied by a form factor ƒLV is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |Vtd|, |Vts| ≪ |Vtb|. All the ƒLVVtb|² determinations, extracted from individual ratios at s√ = 7 and 8 TeV, are combined, resulting in |ƒLVVtb| = 1.02 ± 0.04 (meas.) ± 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.Instituto de Física La Plat