Prompt photon production results by the CDF and D\OCollaborations in the Tevatron Run II at a center of mass energy of $\sqrt{s}$=1.96 TeV are presented. Cross sections for central isolated photons, photon+jet production and photons produced in association with a heavy flavor quark are reported. The measurements are compared to Next-to-Leading order perturbative QCD predictions.
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.
Recent QCD jet production measurements in p-pbar collisions at sqrt(s)=1.96 TeV at the Tevatron Collider at Fermilab are presented. Preliminary: inclusive jet, dijet, isolated photon + jet and Z + jets measurements are compared to available perturbative QCD models.
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 $378 \mathrm{pb}^{-1}$.
A brief overview of the latest status of jet physics studies at the Tevatron in proton-antiproton collisions at $\sqrt{s}=1.96$~TeV is presented. In particular, measurements of the inclusive jet production cross-section, dijet production and searches for new physics, the ratio of the 3-jet to 2-jet production cross-sections, and the three-jet mass are discussed.
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.
We present a measurement of the inclusive jet cross section in ppbar interactions at sqrt{s}=1.96 TeV using 385 pb^{-1} of data collected with the CDF II detector at the Fermilab Tevatron. The results are obtained using an improved cone-based jet algorithm (Midpoint). The data cover the jet transverse momentum range from 61 to 620 GeV/c, extending the reach by almost 150 GeV/c compared with previous measurements at the Tevatron. The results are in good agreement with next-to-leading order perturbative QCD predictions using the CTEQ6.1M parton distribution functions.
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.
An overview of Run I jet physics at the ppbar Fermilab Tevatron Collider with a particular emphasis on inclusive jet cross section measurements is given. The impact of these studies on PDFs constrain from global fits is underlined. Preliminary results on inclusive jet and di-jet mass cross section measurements in Run II are then summarized.
Searches for high-mass resonances in the dijet invariant mass spectrum with one or two jets identified as $b$-jets are performed using an integrated luminosity of $3.2$ fb$^{-1}$ of proton--proton collisions with a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded by the ATLAS detector at the Large Hadron Collider. No evidence of anomalous phenomena is observed in the data, which are used to exclude, at 95% credibility level, excited $b^{*}$ quarks with masses from 1.1 TeV to 2.1 TeV and leptophobic $Z'$ bosons with masses from 1.1 TeV to 1.5 TeV. Contributions of a Gaussian signal shape wit…
Study of Jet Properties at the Tevatron (Proceedings of the XIX Rencontres de Physique de La Vallee d'Aoste) In this contribution, a number of new QCD results on jet production from the CDF and D0 experiments in Run II are discussed in detail.
In this contribution, a comprehensive review of the main aspects of high pt jet physics in Run II at the Tevatron is presented. Recent measurements on inclusive jet and dijet production are discussed using different jet algorithms and covering a wide region of jet transverse momentum and jet rapidity. Several measurements, sensitive to a proper description of soft gluon radiation and the underlying event in hadron collisions, are also shown.
Results are presented from analyses of jet data produced in pbarp collisions at $\sqrt{s}$ = 1960 GeV collected with the DZero and CDF detectors during 2002--03 at the Fermilab Tevatron Collider. Preliminary measurements of the inclusive jet cross section, the dijet mass spectrum, and jet structure are presented.
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.
A measurement of the ratio of the inclusive 3-jet to 2-jet cross sections as a function of the total jet transverse momentum, HT, in the range 0.2 < HT < 2.5 TeV is presented. The data have been collected at a proton-proton centre-of-mass energy of 7 TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 36 inverse picobarns. Comparisons are made between the data and the predictions of different QCD-based Monte Carlo models for multijet production. All models considered in this study are consistent with the data for HT > 0.5 TeV. This measurement extends to an HT r…
We present data on multiple jet production for transverse energies greater than 20 GeV in pbarp collisions at sqrt(s) = 1.8 TeV. QCD calculations in the parton shower approximation (PYTHIA) and in the next-to-leading order approximation (JETRAD) show discrepancies with data for three and four-jet production. This disagreement is especially apparent in multiple jet angular and transverse momentum distributions.
A measurement is presented for the energy flow of minimum bias events in the forward region (3.15 <|η|< 4.9, where ηis the pseudorapidity) of the CMS detector at the LHC for center-of-mass energies sqrt(s) = 0.9 TeV, 2.36 TeV and 7 TeV. The measurement is compared to Monte Carlo simulations, which use a model of multiparton interactions for the underlying event. In addition, production of forward jets was studied for the very first pp collisions at sqrt(s) = 0.9 TeV at LHC.
The relative rates of single- and double- diffractive processes were measured with the ALICE detector by studying properties of gaps in the pseudorapidity distribution of particles produced in proton-proton collisions at $\sqrt{s}$ = 0.9 TeV, 2.76 TeV and 7 TeV. ALICE triggering efficiencies are determined for various classes of events, using a detector simulation validated with data on inclusive particle production. Cross-sections are determined using van der Meer scans to measure beam properties and obtain a measurement of the luminosity.
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.
The WZ production cross section is measured by the CMS experiment at the CERN LHC in proton-proton collision data samples corresponding to integrated luminosities of 4.9 inverse femtobarns collected at sqrt(s)= 7 TeV, and 19.6 inverse femtobarns at sqrt(s)= 8 TeV. The measurements are performed using the fully-leptonic WZ decay modes with electrons and muons in the final state. The measured cross sections for 71 < m[Z] < 111 GeV are sigma(pp to WZ; sqrt(s)= 7 TeV) = 20.14 +/- 1.32 (stat) +/- 1.13 (syst) +/- 0.44 (lumi) pb and sigma(pp to WZ; sqrt(s)= 8 TeV) = 24.09 +/- 0.87 (stat) +/- 1.62 (sy…
We measure the ratio of cross sections, σ(ppbar -> Z + b jet)/σ(ppbar -> Z + jet), for associated production of a Z boson with at least one jet. The ratio is also measured as a function of the jet transverse momentum, jet pseudorapidity, Z boson transverse momentum, and the azimuthal angle between the Z boson and the closest jet for events with at least one b jet. These measurements use data collected by the D0 experiment in Run II of Fermilab's Tevatron ppbar Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of 9.7 fb$^{-1}$. The results are compared …
Photon plus jet production has been studied by the D0 and CDF experiments in Run II of the Fermilab Tevatron Collider at a center of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon plus jet, di-photon and photon plus b jet cross section are presented. They are based on integrated luminosities between 0.2 fb^-1 and 1.1 fb^-1. The results are compared to perturbative QCD calculations in various approximations.
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…
An updated search for heavy narrow resonances decaying to muon or electron pairs using the CMS detector is presented. Data samples from pp collisions at sqrt(s) = 7 TeV and 8 TeV at the LHC, with integrated luminosities of up to 5.3 and 4.1 inverse femtobarns, respectively, are combined. No evidence for a heavy narrow resonance is observed. The analysis of the combined data sets excludes, at 95% confidence level, a Sequential Standard Model Z'[SSM] resonance lighter than 2590 GeV, a superstring-inspired Z'[psi] lighter than 2260 GeV, and Kaluza-Klein gravitons lighter than 2390 (2030) GeV, ass…
We report the observation of energetic jet production in proton-proton collisions at sqrt(s) = 7 TeV, based on about 1 nb^-1 of integrated luminosity collected by the ATLAS detector. The anti-kT algorithm is used to reconstruct jets with pT > 30 GeV and |y| < 2.8. Jets with pT up to ~500 GeV and events with dijet mass up to ~1 TeV are observed. The jet shapes and charged particle flow confirm that the observed jet signal corresponds to collimated flows of particles in the final state.
We present a measurement of the cross sections for the associated production of a $W$ boson with at least one heavy quark jet, $b$ or $c$, in proton-antiproton collisions. Data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ recorded with the D0 detector at the Fermilab Tevatron \ppbar Collider at $\sqrt{s}=1.96$ TeV are used to measure the cross sections differentially as a function of the jet transverse momenta in the range 20 to 150 GeV. These results are compared to calculations of perturbative QCD theory as well as predictions from Monte Carlo generators.
This document reviews several recent measurements at the Fermilab Tevatron, including the cross sections of inclusive jet, dijet production, the cross sections of electroweak boson (W or Z) production in association with inclusive or heavy-flavor (b or c) jets, and b-jet shapes. In addition, searches for new physics using the dijet angular distributions are discussed. These analyses are based on integrated luminosities of 0.3--2.5/fb of p-pbar collisions at \sqrt{s}=1.96 TeV, collected with the CDF and D0 detectors. The results directly test the leading order and next-to leading order calculat…
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 inclusive jet cross-section has been measured in proton-proton collisions at sqrt(s)=2.76 TeV in a dataset corresponding to an integrated luminosity of 0.20pb-1 collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-kt algorithm with two radius parameters of 0.4 and 0.6. The inclusive jet double-differential cross-section is presented as a function of the jet transverse momentum pT and jet rapidity y, covering a range of 20 <= pT < 430 GeV and |y| < 4.4. The ratio of the cross-section to the inclusive jet cross-section measurement at sqrt…
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…
We present results on measurements of jet shapes and jet azimuthal decorrelation from $\overline{p}p$ collisions at $\sqrt{s}=1.8$ TeV using data collected during the 1992--1993 run of the Fermilab Tevatron. Jets are seen to narrow both with increasing $E_T$ and increasing rapidity. While HERWIG, a parton shower Monte Carlo, predicts slightly narrower jets, it describes the trend of the data well; NLO QCD describes qualitative features of the data but is sensitive to both renormalization scale and jet definitions. Jet azimuthal decorrelation has been measured out to five units of pseudorapidit…
Preliminary results on a variety of jet analyses are presented using pp collision data collected by the CMS experiment at $\sqrt{s}$=7 TeV. We report on measurements of the inclusive jet cross sections, the ratio of the inclusive three-jet over two-jet cross sections, the hadronic event shapes, the jet structure and the dijet azimuthal decorrelations. The data distributions are compared with the predictions of Monte Carlo event generators and with perturbative QCD calculations.
Inclusive jet cross sections in Z/gamma^* events, with Z/gamma^* decaying into an electron-positron pair, are measured as a function of jet transverse momentum and jet multiplicity in ppbar collisions at sqrt{s} = 1.96 TeV with the upgraded Collider Detector at Fermilab in Run II, based on an integrated luminosity of 1.7 fb^-1. The measurements cover the rapidity region | yjet | < 2.1 and the transverse momentum range ptjet > 30 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections.
Jet flavour identification in multi-TeV e+e- collisions is expected to provide insights on new phenomena at scales beyond those probed by the LHC. The anticipated high track density and jet collimation represent a new challenge to jet tagging algorithms. A method, based on the sampling of the jet charged multiplicity, sensitive to the long decay length and large decay multiplicity of heavy flavour hadrons is proposed and the expected performances for the tagging of e+e- -> bb events at 3 TeV are discussed.
Inclusive jet cross sections in Z/γ^* events, with Z/γ^* decaying into an electron-positron pair, are measured as a function of jet transverse momentum and jet multiplicity in ppbar collisions at sqrt{s} = 1.96 TeV with the upgraded Collider Detector at Fermilab in Run II, based on an integrated luminosity of 2.5 fb-1. The measurements cover the rapidity region |yjet | < 2.1 and the transverse momentum range ptjet > 30 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections.
The systematic uncertainties of the measurements of the Inclusive Jet Cross Section at the Tevatron and their effect on the chi^2 comparisons between data and theoretical predictions are discussed.
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…
Measurements of the semi-inclusive distribution of charged jets recoiling from a trigger hadron in pp and Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented. This technique provides precise, data-driven subtraction of the large uncorrelated background in jet measurements. It uniquely enables the exploration of medium-induced modification of jet production and acoplanarity over wide phase space, including low transverse momentum ($p_\mathrm{T}$) and large resolution parameter ($R$) jets. This proceeding reports the measurements of medium-induced jet energy redistribution thr…
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.
A measurement is presented of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section as a function of the average transverse momentum, <pT[1,2]>, of the two leading jets in the event. The data sample was collected during 2011 at a proton-proton centre-of-mass energy of 7 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 5.0 inverse femtobarns. The strong coupling constant at the scale of the Z boson mass is determined to be alphaS[MZ] = 0.1148 +/- 0.0014 (exp.) +/- 0.0018 (PDF) +/- 0.0050 (theory), by comparing the ratio in the rang…
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.
Recent analyses by the CDF and D0 Collaborations of jet data produced in proton-antiproton collisions at the Fermilab Tevatron Collider are presented. These include new studies of the inclusive jet production cross section, a measurement of the strong coupling constant, the first measurement of subjet multiplicity of quark and gluon jets, examination of ratios of multijet cross sections and their implications for choice of renormalization scale, and a study of charged jet evolution and energy flow in the underlying event. The results are compared to theoretical predictions.
A study of the substructure of jets with transverse momentum greater than 400 GeV/c produced in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider and recorded by the CDF II detector is presented. The distributions of the jet mass, angularity, and planar flow are measured for the first time in a sample with an integrated luminosity of 5.95 fb^-1. The observed substructure for high mass jets is consistent with predictions from perturbative quantum chromodynamics.
Bottom quark production in pbar-p collisions at sqrt(s)=1.8 TeV is studied with 5 inverse picobarns of data collected in 1995 by the DO detector at the Fermilab Tevatron Collider. The differential production cross section for b jets in the central rapidity region (|y(b)| < 1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, DO results are found to be higher than, but compatible with, next-to-leading-order QCD predictions.
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 an update on the status of the W and Z cross sections in proton-antiproton collisions at 1.96 TeV on behalf of the DZero and CDF collaborations. Preliminary studies of the differential cross sections with different jet multiplicities and as a function of jet transverse energy are also presented.
A search for new resonances decaying into jets containing b-hadrons in $pp$ collisions with the ATLAS detector at the LHC is presented in the dijet mass range from 0.57 TeV to 7 TeV. The dataset corresponds to an integrated luminosity of up to 36.1 fb$^{-1}$ collected in 2015 and 2016 at $\sqrt{s} = 13$ TeV. No evidence of a significant excess of events above the smooth background shape is found. Upper cross-section limits and lower limits on the corresponding signal mass parameters for several types of signal hypotheses are provided at 95% CL. In addition, 95% CL upper limits are set on the c…
Results from studies on exclusive production of electron-position pair, di-photon, and di-jet production at CDF in proton-antiproton collisions at the Fermilab Tevatron are presented. The first observation and cross section measurements of exclusive e+e- and di-jet production in hadron-hadron collisions are emphasized.
A brief survey of the results on diboson production at the Tevatron is presented. Measured cross sections for $Wγ$, $Zγ$, $WW$, and limits on WZ/ZZ are summarized.
This contribution reports preliminary jet results in ppbar collisions at sqrt(s)=1.96 TeV from the CDF and D0 experiments. The jet inclusive cross section, measured using both the Midpoint and the K_T jet clustering algorithm, is compared to next-to-leading order QCD prediction in different rapidity regions. The b-jet inclusive cross section measured exploiting the long lifetime and large mass of B hadrons is presented and compared to QCD prediction. A complementary measurement, using the large branching fraction of B hadrons into muons, is also described. The measurement of two-particle momen…
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.
Jet cross sections have been measured with the ATLAS detector for the first time in proton-proton collisions at center-of-mass energy of t TeV. The measurement uses an integrated luminosity of 17 nb-1 recorded at the Large Hadron Collider. The anti-kt algorithm is used to identify jets, with jet resolution parameters R=0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sec…
We present a measurement of the ratio of multijet cross sections in pp-bar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R3/2, has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the PYTHIA event generator do not agree with the data, while SHERPA provides a reasonable description of the dat…
Measurements of differential cross sections are presented for the production of a Z boson and at least one hadronic jet in proton-proton collisions at sqrt(s) = 7 TeV, recorded by the CMS detector, using a data sample corresponding to an integrated luminosity of 4.9 inverse femtobarns. The jet multiplicity distribution is measured for up to six jets. The differential cross sections are measured as a function of jet transverse momentum and pseudorapidity for the four highest transverse momentum jets. The distribution of the scalar sum of jet transverse momenta is also measured as a function of …
We determine the fraction of events with double parton (DP) scattering in a single ppbar collision at sqrt{s}=1.96 TeV in samples of photon + 3 jet and photon + b/c jet + 2 jet events collected with the D0 detector and corresponding to an integrated luminosity of about 8.7 fb^{-1}. The DP fractions and effective cross sections (sigma_eff) are measured for both event samples using the same kinematic selections. The measured DP fractions range from 0.21 to 0.17, with effective cross sections in the photon + 3 jet and photon + b/c jet + 2 jet samples of sigma_eff^incl = 12.7 +- 0.2 (stat) +- 1.3 …
The ratio of the cross section for $p\bar{p}$ interactions producing a $Z$ boson and at least one $b$ quark jet to the inclusive $Z+{\rm jet}$ cross section is measured using $4.2\ {\rm fb}^{-1}$ of $p\bar{p}$ collisions collected with the \dzero\ detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The $Z\rightarrow\ell^+\ell^-$ candidate events with at least one $b$ jet are discriminated from $Z+$ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is $0.0193\pm0.0027$ for events having a jet wi…
Using the data collected with the DZero detector at sqrt(s)=1.96-TeV, for integrated luminosities of about 180 pb^{-1}, we have measured the ratio of inclusive cross sections for p+pbar->Z+bjet to p+pbar->Z+jet production. The inclusive Z+b-jet reaction is an important background to searches for the Higgs boson in associated ZH production at the Fermilab Tevatron collider. Our measurement is the first of its kind, and relies on the Z->e^+e^- and Z->mu^+mu^- modes. The combined measurement of the ratio yields 0.023 +/- 0.005 for hadronic jets with transverse momenta p_T>20 GeV/c and pseudorapid…
A measurement of the electroweak production cross section of a Z boson and two jets is performed using proton-proton collision data at centre-of-mass energies of 7 and 8 TeV. The data is collected by the CMS experiment at the LHC with an integrated luminosity of 5 and 19 fb$^{-1}$, respectively. A study on the hadronic activity between the two tagging jets is also presented.