Measurement of the inclusive-isolated prompt-photon cross section in p￣p collisions using the full CDF data set

A measurement of the inclusive production cross section of isolated prompt photons in proton-antiproton collisions at center-of-mass energy √s=1.96??TeV is presented. The results are obtained using the full Run II data sample collected with the Collider Detector at the Fermilab Tevatron which corresponds to an integrated luminosity of 9.5??fb?1. The cross section is measured as a function of photon transverse energy EγT in the range 30<EγT<500??GeV and in the pseudorapidity region |ηγ|<1.0. The results are compared with predictions from parton-shower Monte Carlo models at leading order in QCD and from next-to-leading-order perturbative QCD calculations. The latter show good agreement with the measured cross section.journal articl

Search for dark matter in association with a Higgs boson decaying to two photons at √s=13??TeV with the ATLAS detector

A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector corresponding to an integrated luminosity of 36.1??fb?1 of proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015 and 2016. No significant excess over the expected background is observed. Upper limits at 95% confidence level are set on the visible cross section for beyond the Standard Model physics processes and the production cross section times branching fraction of the Standard Model Higgs boson decaying into two photons in association with missing transverse momentum in three different benchmark models. Limits at 95% confidence level are also set on the observed signal in two-dimensional mass planes. Additionally the results are interpreted in terms of 90% confidence-level limits on the dark-matter?nucleon scattering cross section as a function of the dark-matter particle mass for a spin-independent scenario.journal articl

Measurement of the WW and WZ production cross section using final states with a charged lepton and heavy-flavor jets in the full CDF Run II data set

We present a measurement of the total WW and WZ production cross sections in p￣p collision at √s=1.96 TeV in a final state consistent with leptonic W boson decay and jets originating from heavy-flavor quarks from either a W or a Z boson decay. This analysis uses the full data set collected with the CDF II detector during Run II of the Tevatron collider corresponding to an integrated luminosity of 9.4 fb^-1. An analysis of the dijet mass spectrum provides 3.7σ evidence of the summed production processes of either WW or WZ bosons with a measured total cross section of σWW+WZ=13.7±3.9 pb. Independent measurements of the WW and WZ production cross sections are allowed by the different heavy-flavor decay patterns of the W and Z bosons and by the analysis of secondary-decay vertices reconstructed within heavy-flavor jets. The productions of WW and of WZ dibosons are independently seen with significances of 2.9σ and 2.1σ respectively with total cross sections of σWW=9.4±4.2 pb and σWZ=3.7+2.5-2.2 pb. The measurements are consistent with standard-model predictions.journal articl

A New Scintillator Tile/Fiber Preshower Detector for the CDF Central Calorimeter

A detector designed to measure early particle showers has been installed in front of the central CDF calorimeter at the Tevatron. This new preshower detector is based on scintillator tiles coupled to wavelength-shifting fibers read out by multi-anode photomultipliers and has a total of 3,072 readout channels. The replacement of the old gas detector was required due to an expected increase in instantaneous luminosity of the Tevatron collider in the next few years. Calorimeter coverage, jet energy resolution, and electron and photon identification are among the expected improvements. The final detector design, together with the R&D studies that led to the choice of scintillator and fiber, mechanical assembly, and quality control are presented. The detector was installed in the fall 2004 Tevatron shutdown and started collecting colliding beam data by the end of the same year. First measurements indicate a light yield of 12 photoelectrons/MIP, a more than two-fold increase over the design goals.Comment: 5 pages, 10 figures (changes are minor; this is the final version published in IEEE-Trans.Nucl.Sci.

Search for new phenomena in dijet events using 37??fb?1 of pp collision data collected at √s=13??TeV with the ATLAS detector

Dijet events are studied in the proton-proton collision data set recorded at √s=13??TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016 corresponding to integrated luminosities of 3.5??fb?1 and 33.5??fb?1 respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches a new method for fitting the background component of the invariant mass distribution is employed. The data set is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded and limits are set on quantum black holes heavy W′ bosons W? bosons and a range of masses and couplings in a Z′ dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set using a new approach allowing factorization of physics and detector effects. From the angular distributions a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.journal articl

Search for the Exotic Meson X(5568) with the Collider Detector at Fermilab

A search for the exotic meson X(5568) decaying into the B0sπ± final state is performed using data corresponding to 9.6  fb−1 from p¯p collisions at √s=1960  GeV recorded by the Collider Detector at Fermilab. No evidence for this state is found and an upper limit of 6.7% at the 95% confidence level is set on the fraction of B0s produced through the X(5568)→B0sπ± process

Tevatron Run II combination of the effective leptonic electroweak mixing angle

Drell-Yan lepton pairs produced in the process p¯p→ℓ+ℓ−+X through an intermediate γ∗/Z boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter sin2θlepteff using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9–10  fb−1 of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, sin2θlepteff=0.23148±0.00033. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter sin2θW, or equivalently the W-boson mass MW, using the zfitter software package yields sin2θW=0.22324±0.00033 or equivalently, MW=80.367±0.017  GeV/c2

Measurement of the tt¯ production cross-section using eμ events with b-tagged jets in pp collisions at √s=13TeV with the ATLAS detector

This paper describes a measurement of the inclusive top quark pair production cross-section (View the MathML sourceσtt¯) with a data sample of View the MathML source3.2fb−1 of proton–proton collisions at a centre-of-mass energy of View the MathML sources=13TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b -tagged jets are counted and used to determine simultaneously View the MathML sourceσtt¯ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be:View the MathML sourceσtt¯=818±8(stat)±27(syst)±19(lumi)±12(beam) pb,Turn MathJax onwhere the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented

Measurement of the inclusive jet cross-sections in proton-proton collisions at s√=8 TeV with the ATLAS detector

Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of s√=8 TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb−1. Double-differential cross-sections are measured for jets defined by the anti-kt jet clustering algorithm with radius parameters of R = 0.4 and R = 0.6 and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed