Measurements are presented of differential cross sections for the production of Z bosons in association with at least one jet initiated by a charm quark in pp collisions at $\sqrt{s} =$ 13 TeV. The data recorded by the CMS experiment at the LHC correspond to an integrated luminosity of 35.9 fb$^{-1}$. The final states that contain a pair of electrons or muons that are the decay products of a Z boson, and a jet consistent with being initiated by a charm quark produced in the hard interaction. Differential cross sections as a function of the $p_\mathrm{T}$ of the Z boson and $p_\mathrm{T}$ of the charm jet are compared with predictions from Monte Carlo event generators. The inclusive production cross section 405.4 $\pm$ 5.6 (stat) $\pm$ 24.3 (exp) $\pm$ 3.7 (theo) pb, is measured in a fiducial region requiring both leptons to have $\vertη\vert$ $\lt$ 2.4 and $p_\mathrm{T}$ $\gt$ 10 GeV, at least one lepton with $p_\mathrm{T}$ $\gt$ 26 GeV, and a mass of the pair in the range 71-111 GeV, while the charm jet is required to have $p_\mathrm{T}$ $\gt$ 30 GeV and $\vertη\vert$ $\lt$ 2.4. These are the first measurements of these cross sections in proton-proton collisions at 13 TeV.
A selection of recent jet measurements are presented from the ALICE experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}=13$ TeV, focusing on substructure results for inclusive and charmed jets. The groomed jet momentum fractions ($z_g$) of inclusive full jets are shown for various jet resolution parameters, and $z_g$, the groomed splitting radius ($θ_g$) as well as the number of soft drops ($n_{\rm SD}$) of inclusive and charmed charged-particle jets are compared. The first direct measurement of the dead cone in heavy-flavor jets is also presented. Furthermore, the parallel mom…
Measurements of cross sections for events with charm and beauty jets in deep inelastic scattering at HERA are presented. Events with jets of transverse energy E_T^jet > 6 GeV and pseudorapidity -1.0 < eta^jet < 1.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q^2 > 6 GeV^2 and inelasticity variable 0.07 < y < 0.625. Measurements are also made requiring a jet in the Breit frame with E_T^*jet > 6 GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb^-1. The numbers of charm and beauty …
We present a search for the pair production of scalar top quarks, $\tilde{t}$, using 995 pb$^{-1}$ of data collected in $p\bar{p}$ collisions with the D0 detector at the Fermilab Tevatron Collider at $\sqrt{s} = 1.96$ TeV. Both scalar top quarks are assumed to decay into a charm quark and a neutralino ($\tildeχ^{0}_{1}$), where $\tildeχ^{0}_{1}$ is the lightest supersymmetric particle. This leads to a final state with two acoplanar charm jets and missing transverse energy. We find the yield of such events to be consistent with the standard model expectation, and exclude sets of $\tilde{t}$ and…
The latest D0 and CDF measurements of the important $W+{\rm jets}$ and $Z/γ^{*}+{\rm jets}$ processes are described, along with a discussion of the comparisons that have been made to LO and NLO perturbative QCD predictions.
A search for supersymmetric partners of top quarks decaying as $\tilde{t}_1\to c\tildeχ^0_1$ and supersymmetric partners of charm quarks decaying as $\tilde{c}_1\to c\tildeχ^0_1$, where $\tildeχ^0_1$ is the lightest neutralino, is presented. The search uses 36.1 ${\rm fb}^{-1}$ $pp$ collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider and is performed in final states with jets identified as containing charm hadrons. Assuming a 100% branching ratio to $c\tildeχ^0_1$, top and charm squarks with masses up to 850 GeV are excluded at 95%…
We present the first measurements of the ratios of cross sections, σ(ppbar -> Z+c jet)/σ(ppbar -> Z+jet) and σ(ppbar -> Z+c jet)/σ(ppbar -> Z+b jet) for the associated production of a Z boson with at least one charm or bottom quark jet. Jets have transverse momentum p_{T}>20 GeV and pseudorapidity |η|<2.5. These cross section ratios are measured differentially as a function of jet and $Z$ boson transverse momenta, based on 9.7 fb^{-1} of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt(s) = 1.96 TeV. The measurements show significant deviations from per…
This report summarises studies of associated production of electroweak gauge bosons and jets in proton-proton collisions at LHC with center of mass energy of 8 and 13 TeV. It is based on a selection of results published by the ATLAS Collaboration in the first half of 2017.
We present predictions for the inclusive production of charm jets in proton-proton collisions at 7 TeV. Several CTEQ parton distribution functions (PDFs) of the CTEQ6.6M type are employed, where two of the CTEQ6.6 PDFs have intrinsic charm. At large enough jet transverse momentum and large jet rapidity, the intrinsic charm content can be tested.
The study of the associated production of vector bosons and jets constitutes an excellent environment to check numerous QCD predictions. Total and differential cross sections of vector bosons produced in association with jets have been studied in pp collisions using CMS data. Differential distributions as a function of a broad range of kinematical observables are measured and compared with theoretical predictions. In this talk, studies of associated production of vector bosons with inclusive jets and with jets originating from heavy-flavour quarks will be summarized.
Presented here is a study of jets produced in association with vector bosons production in pp collisions at \surds = 7 TeV using the full CMS 2010 data set, corresponding to an integrated luminosity of 36 \pm 1.4 pb-1. The transverse energy distribution of the reconstructed leading jets is measured and compared to theoretical expectations. The jet multiplicity distributions are corrected for efficiency and unfolded. The ratios of multiplicities, σ(V+ \geq n jets)/σ(V+ \geq (n - 1) jets) and σ(V+ \geq n jets)/σ(V) where n stands for number of jets, are also presented along with the first test o…
Understanding the associated production of jets and vector bosons is of paramount importance for the top quark physics, for the Higgs boson and for many new physics searches. In this contribution, recent measurements of W/Z+jets and Z+b-jets processes by the D0 experiment are presented. The measurements are compared to theoretical predictions from next-to-leading order (NLO) perturbative QCD calculations where available, and to several Monte Carlo model predictions.
Ratios of cross sections, $σ$(Z+c jets) / $σ$(Z+jets), $σ$(Z+b jets) / $σ$(Z+jets), and $σ$(Z+c jets) / $σ$(Z+b jets) in the associated production of a Z boson with at least one charm or bottom quark jet are measured in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The data sample, collected by the CMS experiment at the CERN LHC, corresponds to an integrated luminosity of 35.9 fb$^{-1}$, with a fiducial volume of $p_\mathrm{T}$ $>$ 30 GeV and $|η|$ $<$ 2.4 for the jets, where $p_\mathrm{T}$ and $η$ represent transverse momentum and pseudorapidity, respectively. The Z boson candidates come f…
A first measurement of the $\mathrm{b}$ quark fragmentation function at the LHC is presented. Charmed meson candidates produced via semi-leptonic $\mathrm{t\overline{t}}$ decays ($\mathrm{t} \to \mathrm{b}\mathrm{W} \to$ b-jet $\ell ν$) are used as a proxy for the parent $\mathrm{B}$ meson. Templates are generated at various values of the fragmentation shape parameter $r_{\mathrm{b}}$, and are fit to the data to measure the value of $r_{\mathrm{b}}$. The final fit result is $r_{\mathrm{b}}=0.855 \pm 0.037\;\mathrm{(stat)} \pm 0.031\;\mathrm{(syst)}$. This is the first measurement of the $\math…
We present the first measurement of the production cross section of a W boson with a single charm quark (c) in p-pbar collisions at sqrt(s)=1.96 TeV, using soft muon tagging of c jets. In a data sample of ~1.8 fb-1, recorded with the CDF II detector at the Fermilab Tevatron, we select events with W+1 or 2 jets. We use the charge correlation between the W and the muon from the semileptonic decay of a charm hadron to extract the Wc signal. We measure sigma_{Wc}(p_{Tc}>20 GeV/c, |η_c|<1.5)\times BR(W->\ellν) = 9.8+/-3.2 pb, in agreement with theoretical expectations.
We present predictions for the inclusive production of charm jets in proton-proton collisions at 2.76 and 5.02 TeV. The charm-quark is considered massless. In this scheme we find that the ratio of the next-to-leading order to the leading order cross section (K factor) is almost equal to one depending essentially on the choice of the renormalization and factorization scale. Adding non-pertubative corrections obtained from Pythia Monte Carlo calculations lead to reasonable agreement with experimental c-jet cross sections obtained by the CMS collaboration.
The first observation of the production of a $W$ boson with a single charm quark ($c$) jet in $p\bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ is reported. The analysis uses data corresponding to 4.3 fb$^{-1}$, recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from charm-hadron semileptonic decay within a hadronic jet, and a $Wc$ signal is observed with a significance of 5.7 standard deviations. The production cross section $σ_{Wc}(p_{Tc}>20 {\rm GeV}/c, |η_c|<1.5)\times B(W\rightarrow \ellν)$ is …
We present a search for the Standard Model Higgs boson produced in association with a Z or a W boson, using data collected with the CDF II detector at the Tevatron accelerator. A scenario where the Z decays into neutrinos or leptons originating from the W-decay escape detection and the Higgs decays into a $b\overline{b}$ pair is considered. Therefore the expected signature is large missing transverse energy ($\etmiss$), no isolated leptons, and two b-jets. We present the preliminary results in this search using 2.1$fb^{-1}$ of data collected by CDF.
We report on the measurements of inclusive W+jets and Z+jets cross sections in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the bosons, are presented as a function of jet multiplicity, the transverse momentum of the jets and the quantity HT which is the scalar sum of the pT in the event. Measurements are also presented of the ratios of cross sections. The measured cross sections are compared to different particle-level predictions, based on perturbative QCD, where the measured W+3jet cross section is for the f…
Measurements of the production of jets in association with a W/Z boson in proton-proton collisions are presented using data collected by the ATLAS experiment at LHC at sqrt s = 8 and 13 TeV. Several kinematic regimes are explored with various approaches to probe different aspects of these processes. The differential cross sections of a Z boson in association with jets with pT > 30 GeV and |y|< 2.5 at sqrt s = 13 TeV are measured in a fiducial phase space, probing strong interactions that completely dominate in these processes, while measurements of a W boson in association with at least two je…
This document is dedicated to recent results on the measurements of a vector boson production associated with jets (V+jets) using CMS detector experiment, with a central proton-proton (pp) collision energy of respectively 8 TeV (RunI) and 13 TeV (RunII). The vector boson can be a W boson, Z boson, or photon(γ). The jets are of any flavor, as well as the ones containing heavy flavor quarks, such as bottom(b) quarks. The inclusive cross sections of V+jets processes and differential cross sections as a function of various kinematic observables are presented and compared to several theoretical pre…
The latest results on charm-tagged jets and open-charm production obtained with \mbox{ALICE} at the LHC are presented. The baryon-to-meson ratios for $\mathrm{Λ^+_c}$, $\mathrm{Σ^{0,+,++}_c}$ and $\mathrm{Ξ^{0,+}_c}$ measured in pp collisions at $\sqrt{s}=13\ \mathrm{TeV}$ are discussed. The measurements of the jet-momentum fraction carried by the $\mathrm{D^0}$ meson and $\mathrm{Λ^+_c}$ baryon in pp collisions at $\sqrt{s}=13\ \mathrm{TeV}$ are reported, and the number of leading-parton splittings $n_{SD}$ for $\mathrm{D^0}$-tagged and inclusive jets in pp collisions at $\sqrt{s}=13\ \mathrm…
The first measurement of the inclusive cross section for top quark pairs ($\mathrm{t\bar{t}}$) produced in association with two additional charm jets is presented. The analysis uses the dileptonic final states of $\mathrm{t\bar{t}}$ events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 41.5 fb$^{-1}$, recorded by the CMS experiment at the LHC. A new charm jet identification algorithm provides input to a neural network that is trained to distinguish among $\mathrm{t\bar{t}}$ events with two additional charm ($\mathrm…
The production of a W boson in association with a single charm quark is studied using 4.6 fb^-1 of pp collision data at sqrt(s)=7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from vari…
We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree well with the data, in particular for large momentum fractions of the the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favou…
Many measurements at the LHC require efficient identification of heavy-flavour jets, i.e. jets originating from bottom (b) or charm (c) quarks. An overview of the algorithms used to identify c jets is described and a novel method to calibrate them is presented. This new method adjusts the entire distributions of the outputs obtained when the algorithms are applied to jets of different flavours. It is based on an iterative approach exploiting three distinct control regions that are enriched with either b jets, c jets, or light-flavour and gluon jets. Results are presented in the form of correct…
The ratio of the production cross sections for W and Z bosons in association with jets has been measured in proton-proton collisions at $\sqrt{s}$ = 7 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6 fb$^{-1}$. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum $p_T$ > 30 GeV and jet rapidity $|y|$ < 4.4. The measurements are compared to next-to-leading-order perturb…
Results are presented on the production of jets of particles in association with a Z/gamma* boson, in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector. The analysis includes the full 2010 data set, collected with a low rate of multiple proton-proton collisions in the accelerator, corresponding to an integrated luminosity of 36 pb^-1. Inclusive jet cross sections in Z/gamma* events, with Z/gamma* decaying into electron or muon pairs, are measured for jets with transverse momentum pT > 30 GeV and jet rapidity |y| < 4.4. The measurements are compared to next-to-leading-order pe…
We present results on the production of jets of particles in association with a $Z/γ^*$ boson, in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector at the LHC. The analysis includes the full 2010 data set, collected with a low rate of multiple proton-proton collisions in the accelerator, corresponding to an integrated luminosity of $36 \rm pb^{-1}$. Inclusive jet cross sections in $Z/γ^*$ events, with $Z/γ^*$ decaying into electron or muon pairs, are measured for jets with transverse momentum $p_T >$ 30 GeV and jet rapidity $|y| < 4.4$. The measurements are compared to nex…
We present a search for the Standard Model Higgs boson produced in association with a Z or a W boson, using data collected with the CDF II detector at the Tevatron accelerator. A scenario where the Z decays into neutrinos or charged leptons originating from the W-decay escape detection and the Higgs decays into a $b\overline{b}$ pair is considered. Therefore the expected signature is large missing transverse energy ($\etmiss$), no isolated leptons, and two $b$-jets. We present the preliminary results in this search using 1.7$fb^{-1}$ of data collected by CDF and the work on future improvements…
Measurements of the production of jets of particles in association with a Z boson in pp collisions at sqrt(s) = 7 TeV are presented, using data corresponding to an integrated luminosity of 4.6/fb collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transverse momentum pT > 30 GeV and rapidity |y| < 4.4. The results are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators based on leadin…
We present a search for anomalous production of heavy-flavor quark jets in association with a W boson at the Fermilab Tevatron ppbar Collider. This search is conducted through an examination of the exclusive jet spectrum of W+jets final states in which the heavy-flavor quark content has been enhanced by requiring at least one tagged jet in an event. Jets are tagged by the combined use of two algorithms, one based on semileptonic decays of b/c hadrons, and the other on their lifetimes. We compare data in e+jets (164 pb-1) and mu+jets (145 pb-1) channels, collected with the D0 detector at sqrt{s…
An observation of electroweak $W^{\pm}Z$ production in association with two jets in proton-proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of $\sqrt{s} =$ 13 TeV are used, corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of $W^{\pm}Z$ bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section…
Measurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from $pp$ collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb$^{-1}$. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measure…
The inclusive cross-section for jet production in association with a Z boson decaying into an electron-positron pair is measured as a function of the transverse momentum and the absolute rapidity of jets using 19.9 fb$^{-1}$ of $\sqrt s = 8$ TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The measured Z + jets cross-section is unfolded to the particle level. The cross-section is compared with state-of-the-art Standard Model calculations, including the next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations, correcte…
Evidence for electroweak production of two jets in association with a $Zγ$ pair in $\sqrt{s} = 13$ TeV proton$-$proton collisions at the Large Hadron Collider is presented. The analysis uses data collected by the ATLAS detector in $2015$ and $2016$ that corresponds to an integrated luminosity of $36.1~\mathrm{fb}^{-1}$. Events that contain a $Z$ boson candidate decaying leptonically into either $e^{+}e^{-}$ or $μ^{+}μ^{-}$, a photon, and two jets are selected. The electroweak component is measured with observed and expected significances of $4.1$ standard deviations. The fiducial cross-section…
New results on charm quark production at HERA in an increased phase space in deep-inelastic scattering and photoproduction are discussed. Single & double-differential cross section distributions are compared to next-to-leading order QCD calculations as well as to MC@NLO in the photoproduction regime. The charm contribution to the proton structure, F_2^cc(x,Q^2), is determined with different experimental techniques and finally combined.
This paper presents cross sections for the production of a W boson in association with jets, measured in proton--proton collisions at $\sqrt{s}=7$ TeV with the ATLAS experiment at the Large Hadron Collider. With an integrated luminosity of $4.6 fb^{-1}$, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of 1 TeV and multiplicities up to seven associated jets. The production cross sections for W bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also present…
The production cross section of a W boson in association with two b jets is measured using a sample of proton-proton collisions at sqrt(s) = 8 TeV collected by the CMS experiment at the CERN LHC. The data sample corresponds to an integrated luminosity of 19.8 inverse femtobarns. The W bosons are reconstructed via their leptonic decays, W to l nu, where l = mu or e. The fiducial region studied contains exactly one lepton with transverse momentum pt[l] > 30 GeV and pseudorapidity abs(eta[l]) < 2.1, with exactly two b jets with pt > 25 GeV and abs(eta) < 2.4 and no other jets with pt > 25 GeV and…
Cross sections for the production of a Z boson in association with jets in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 8 TeV are measured using a data sample collected by the CMS experiment at the LHC corresponding to 19.6 inverse femtobarns. Differential cross sections are presented as functions of up to three observables that describe the jet kinematics and the jet activity. Correlations between the azimuthal directions and the rapidities of the jets and the Z boson are studied in detail. The predictions of a number of multileg generators with leading or next-to-leading …
A measurement is presented of the cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of sqrt(s)=7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb^-1. The event selection requires a Z boson decaying into high pt electrons or muons, and a b-jet, identified by its displaced vertex, with transverse momentum pt>25 GeV and rapidity |y|<2.1. After subtraction of backgrounds, the yield is extracted from the vertex mass distribution of the candidat…
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pt) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 inverse femtobarns. T…
We present a measurement of the cross section for W-boson production in association with jets in pbar-p collisions at sqrt(s)=1.96 TeV. The analysis uses a data sample corresponding to an integrated luminosity of 320 pb^-1 collected with the CDF II detector. W bosons are identified in their electron decay channel and jets are reconstructed using a cone algorithm. For each W+>= n-jet sample (n= 1 - 4) we measure dsigma(ppbar =>W+>=n-jet)/dE_T^(nth-jet) x BR(W => e nu) with respect to the transverse energy E_T of the n^th-highest E_T jet above 20 GeV, and the total cross section sigma(ppbar =>W+…
The LHC experiments ATLAS and CMS have measured V+jets and ttbar+jets final states over a large energy range in data collected between 2010 and 2012 at sqrt(s) = 7 TeV and sqrt(s) = 8 TeV. The results have been compared to pQCD calculations at NLO and have been used to validate novel Monte Carlo techniques.
The cross sections for the production of tt-bar bb-bar and tt-bar jj events and their ratio sigma[tt-bar bb-bar]/sigma[tt-bar jj] are measured using data corresponding to an integrated luminosity of 2.3 inverse femtobarns collected in pp collisions at sqrt(s) = 13 TeV with the CMS detector at the LHC. Events with two leptons (e or mu) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022 +/- 0.003 (stat) +/- 0.006 (syst), the cross section sigma[tt-bar bb-bar] is 4.0 +/- 0.6…
We calculate the decay rate of bottomonium to two-charm quark jets $Υ\to c \bar c$ at the tree level and one-loop level including color-singlet and color-octet $b \bar b$ annihilations. We find that the short distance coefficient of the color-octet piece is much larger than the color-singlet piece, and that the QCD correction will change the endpoint behavior of the charm quark jet. The color-singlet piece is strongly affected by the one-loop QCD correction. In contrast, the QCD correction to the color-octet piece is weak. Once the experiment can measure the branching ratio and energy distribu…
Measurements of differential production cross-sections of a $Z$ boson in association with $b$-jets in $pp$ collisions at $\sqrt{s}=7$ TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb$^{-1}$ recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a $Z$ boson decaying into an electron or muon pair, and containing $b$-jets. For events with at least one $b$-jet, the cross-section is presented as a function of the $Z$ boson transverse momentum and rapidity, together with the inclusive $b$-jet cro…
This paper presents a measurement of the production cross-section of a $Z$ boson in association with $b$-jets, in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 35.6 fb$^{-1}$. Inclusive and differential cross-sections are measured for events containing a $Z$ boson decaying into electrons or muons and produced in association with at least one or at least two $b$-jets with transverse momentum $p_\textrm{T}>$ 20 GeV and rapidity $|y| < 2.5$. Predictions from several Monte Carlo generat…
This Letter reports measurements of differential cross sections for the production of two Z bosons in association with jets in proton-proton collisions at $\sqrt{s} =$ 8 and 13 TeV. The analysis is based on data samples collected at the LHC with the CMS detector, corresponding to integrated luminosities of 19.7 and 35.9 fb$^{-1}$ at 8 and 13 TeV, respectively. The measurements are performed in the leptonic decay modes ZZ $\to\ell^+ \ell^- \ell'^+ \ell'^-$, where $\ell,\ell' =$ e, $μ$. The differential cross sections as a function of the jet multiplicity, the transverse momentum $p_\mathrm{T}$,…
Search for supersymmetry in final states with missing transverse momentum and charm-tagged jets using 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector
A search is performed for localised excesses in dijet mass distributions of low-dijet-mass events produced in association with a high transverse energy photon. The search uses up to 79.8 fb$^{-1}$ of LHC proton-proton collisions collected by the ATLAS experiment at a centre-of-mass energy of 13 TeV during 2015-2017. Two variants are presented: one which makes no jet flavour requirements and one which requires both jets to be tagged as $b$-jets. The observed mass distributions are consistent with multi-jet processes in the Standard Model. The data are used to set upper limits on the production …
The purely electroweak (EW) cross section for the production of two jets in association with a Z boson, in proton-proton collisions at sqrt(s) = 8 TeV, is measured using data recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The electroweak cross section for the lljj final state (with l = e or mu and j representing the quarks produced in the hard interaction) in the kinematic region defined by M[ll] > 50 GeV, M[jj] > 120 GeV, transverse momentum pt[j] > 25 GeV, and pseudorapidity abs(eta[j]) < 5, is found to be sigma[EW](lljj)…
We present a search for technicolor particles decaying into $b\bar b$, $b\bar c$ or $b\bar u$ and produced in association with $W$ bosons in $p\bar p$ collisions at $\sqrt{s}= 1.96 \mathrm{TeV}$. The search uses approximately $1.9 \mathrm{fb}^{-1}$ of the dataset accumulated in the CDF II detector at the Fermilab Tevatron. We select events matching the $W$ + 2-jets signature and require at least one jets to be identified as $b$-quark jets. In the case of exactly one vertex $b$-tagged events, we apply a neural network flavor separator to reject contamination from charm and light quark jets. The…
This Letter presents the observation and measurement of electroweak production of a same-sign $W$ boson pair in association with two jets using 36.1 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of $\sqrt{s}=13$ TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of $69 \pm 7…
Measurements of the production cross section of a $Z$ boson in association with jets in proton-proton collisions at $\sqrt{s} = 13$ TeV are presented, using data corresponding to an integrated luminosity of 3.16 fb$^{-1}$ collected by the ATLAS experiment at the CERN Large Hadron Collider in 2015. Inclusive and differential cross sections are measured for events containing a $Z$ boson decaying to electrons or muons and produced in association with up to seven jets with $p_T > 30$ GeV and $|y| <2.5$. Predictions from different Monte Carlo generators based on leading-order and next-to-leading-or…
Vector boson production in association with jets is an important process to test perturbative quantum chromodynamics and also a background process in top quark analyses. Measurements on vector boson production in association with light and heavy flavour jets are presented, performed by the D0 and CDF collaborations at the Tevatron as well as the ATLAS and CMS experiments at LHC. Techniques applied in top quark analyses to estimate the vector boson+jets background are also discussed.
