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the top quark , the heaviest fundamental particle with a mass about @xmath2 @xcite , plays an important role in the study of the electroweak symmetry breaking ( higgs boson ) as well as in the search of physics beyond the standard model ( bsm ) . moreover , the production of top quark anti - quark pairs is one of the main backgrounds in many of the processes related with the standard model ( sm ) and bsm , and it is crucial to measure its production cross section with very high precision .    the large hadron collider ( lhc ) has been in operation since 2009 , producing proton - proton collisions with a center of mass energy of @xmath3 until 2011 and @xmath1 in 2012 . this document presents the most recent measurements of the inclusive @xmath4 cross section with data collected using the atlas @xcite and the cms @xcite detectors . the most recent theoretical predictions for the top quark pair production cross section ( @xmath5 ) are @xmath6 and @xmath7 @xcite for a top - quark mass of @xmath8 . according to the sm , top quarks decay into a w boson and a b quark almost 100% of the times . this leads to final states with two w bosons and two jets coming from the b quark fragmentation . when both w bosons decay leptonically , the event contains two high momentum leptons with opposite charge , two undetected neutrinos which are measured as missing energy in the plane transverse to the beam axis ( @xmath9 ) , and at least two jets , where two of them originate from b quarks . the dilepton channel is optimal to measure the inclusive @xmath4 cross section due to the small background contribution from other sm processes . as will be presented in the following sections , the uncertainty on @xmath5 measurement in the dilepton channel is dominated by systematic errors . this analysis performed by the atlas collaboration @xcite exploits the fact that the @xmath4 , @xmath12 and @xmath11 processes dominate the muon - electron final state . the simultaneous measurement of all three cross sections is performed at @xmath3 using the full 2011 dataset . the cross section of these processes is extracted through a fit in a two - dimensional parameter space defined by the missing transverse energy ( @xmath9 ) and the jet multiplicity ( @xmath13 ) . events from @xmath4 production have large @xmath9 and large @xmath13 , whereas @xmath12 events have large @xmath9 but small @xmath13 , and finally , drell - yan ( @xmath11 ) events are characterized by small @xmath9 and small @xmath13 . the results obtained for the @xmath4 process are : @xmath14 the fiducial phase space is defined by the lepton cuts applied in the analysis : @xmath15 and @xmath16 , and it includes the @xmath17 decay mode . figure [ atlas_simul ] shows the best fit for the cross section values with likelihood contours obtained from the simultaneous fit , overlayed with theoretical cross section predictions in the case of the total ( nnlo ) and fiducial ( nlo ) phase space . the theoretical predictions are calculated for different pdf sets . a better data - mc agreement is obtained when nnlo calculations are used .     and drell - yan / ww processes @xcite . in the case of the total cross section , the result is compared to nnlo available prediction , while the fiducial cross section is compared to the nlo calculation . , title="fig:",scaledwidth=40.0% ]   and drell - yan / ww processes @xcite . in the case of the total cross section , the result is compared to nnlo available prediction , while the fiducial cross section is compared to the nlo calculation . , title="fig:",scaledwidth=40.0% ] +  ( a)(b ) the following analysis is a dedicated measurement of the @xmath4 cross section in the muon - electron decay mode using the full 2011 and 2012 datasets @xcite . the @xmath4 production cross section ( @xmath5 ) is determined by counting the numbers of @xmath18 events with exactly one and exactly two b - tagged jets . in order to reduce the systematic uncertainties , the @xmath5 is extracted simultaneously with the combined probability to reconstruct and tag a b - jet from the top - quark decay . the obtained cross section results in the @xmath18 channel are shown in equation [ 7 - 8tevatlas ] with the corresponding ratio ( @xmath20 ) . figure [ atlas_btag ] shows the b - tagged jet distribution for the @xmath0 and @xmath1 datasets . @xmath21     events in ( a ) @xmath22 and ( b ) @xmath23 data @xcite . the data is compared to the expectation from signal and background simulations . , title="fig:",scaledwidth=40.0% ]   events in ( a ) @xmath22 and ( b ) @xmath23 data @xcite . the data is compared to the expectation from signal and background simulations . , title="fig:",scaledwidth=40.0% ] +  ( a)(b ) the amount of data studied in this analysis corresponds to @xmath24 of proton - proton collisions taken by the cms detector at @xmath1 @xcite . the extraction of @xmath5 is performed in all three dileptonic final states ( @xmath25 , @xmath26 and @xmath18 , including @xmath27 as signal ) . the final @xmath5 result is obtained with a simple and robust cut - based analysis method . equation [ 8tev_cms ] presents the results for all three channels . figure [ cms_dilepton_8tev ] shows the b - tagged jet multiplicity and the @xmath9 distributions for the muon - electron channel , the decay mode with the smallest background contamination . @xmath28     distributions for the muon - electron decay mode @xcite . the expected distributions for @xmath4 signal and background sources are shown by stacked histograms ; data are shown by black dots . , title="fig:",scaledwidth=40.0% ]   distributions for the muon - electron decay mode @xcite . the expected distributions for @xmath4 signal and background sources are shown by stacked histograms ; data are shown by black dots . , title="fig:",scaledwidth=40.0% ] +  ( a)(b ) the cms collaboration has measured the production cross section of @xmath4 pairs by considering dilepton decays where one of the w bosons decays into taus ( @xmath30 ) @xcite . the identification of the @xmath29 lepton is performed by means of its hadronic decay products . this decay channel has particular interest because it contributes as a background process in the search for a charged higgs boson @xcite ( @xmath31 with @xmath32 ) . the @xmath4 cross section is extracted with a cut and count method using the @xmath33 of @xmath1 data collected by the cms detector in 2012 . equation [ taucms ] presents the results for the muon - tau ( @xmath34 ) and electron - tau ( @xmath35 ) channels . figure [ cms_dilepton_8tev ] shows the reconstructed @xmath36 and the b - tagged jet multiplicity distributions for the two channels combined . @xmath37    ) and ( b ) the b - tagged jet multiplicity for the @xmath38 and @xmath34 channels combined @xcite . data ( points ) are compared with the sum of signal and background yields . , title="fig:",scaledwidth=40.0% ] ) and ( b ) the b - tagged jet multiplicity for the @xmath38 and @xmath34 channels combined @xcite . data ( points ) are compared with the sum of signal and background yields . , title="fig:",scaledwidth=40.0% ] +  ( a)(b ) the lhc has a very strong program in the measurement of the inclusive top quark pair production cross section with its two main detectors : atlas and cms . the results presented in this document have reached an unprecedented precision of @xmath39 challenging the current theoretical predictions at nnlo+nnll . figure [ cms_atlas_summary ] shows the most precise measurements performed by cms and atlas detectors at @xmath0 and @xmath1 compared with the last theoretical calculations . all results are found to be in agreement with the standard model prediction .    ) compared to the nnlo qcd calculation complemented with nnll resummation . the measurements and the theory calculation is quoted at @xmath40 . , scaledwidth=76.0% ] 9 atlas , cdf , cms , dcollaboration , `` first combination of tevatron and lhc measurements of the top - quark mass '' , http://www.arxiv.org/abs/1403.4427[arxiv:1403.4427 ] . atlas collaboration , `` the atlas experiment at the cern large hadron collider'',http://iopscience.iop.org/1748 - 0221/3/08/s08003[jinst 3 ( 2008 ) s08003 ] . cms collaboration , `` the cms experiment at the cern lhc '' , http://iopscience.iop.org/1748-0221/3/08/s08004[jinst 3 ( 2008 ) s08004 ] . m. czakon , p. fiedler , and a. mitov , `` total top - quark pair - production cross section at hadron colliders through @xmath41 '' , ( 2013 ) . http://www.arxiv.org/abs/1303.6254[phys . ( 2013 ) 252004 ] . atlas collaboration , `` simultaneous measurements of the top quark pair , @xmath10 , and @xmath42 @xmath43 @xmath44 production cross sections in pp collisions with the atlas detector at @xmath22 '' , _ http://arxiv.org/abs/1407.0573[arxiv:1407.0573 ] _ atlas collaboration , `` measurement of the @xmath4 production cross - section using @xmath45 events with b - tagged jets in pp collisions at @xmath46 and @xmath47 with the atlas detector '' , _ c74 ( 2014 ) 3109 ] _ cms collaboration , `` measurement of the @xmath4 production cross section in the dilepton channel in pp collisions at @xmath48 '' , _ http://link.springer.com/article/10.1007%2fjhep02%282014%29024[jhep 02 ( 2014 ) 024 ] _ cms collaboration , `` measurement of the ttbar production cross section in pp collisions at @xmath1 in the @xmath35 and @xmath34 dilepton final states '' , _ b 739 ( 2014 ) 23 ] _ j. f. gunion , h. e. haber , g. l. kane , and s. dawson , `` the higgs hunter s guide '' . frontiers in physics . addison - wesley , 1990 . cms collaboration , `` measurement of the ratio b(@xmath49)/b(@xmath50 ) in pp collisions at @xmath51 '' , _ http://dx.doi.org/10.1016/j.physletb.2014.06.076[plb 736 ( 2014 ) 33 ] _ atlas collaboration , `` measurement of the @xmath4 production cross section in the @xmath29+jets channel using the atlas detector '' , _ j. c , 73 3 ( 2013 ) ] _ cms collaboration , `` measurement of the @xmath4 production cross section in the @xmath52 channel in pp collisions at @xmath22 '' , _ http://dx.doi.org/10.1140/epjc/s10052-013-2386-x[epj c73 ( 2013 ) 2386 ] _
this document presents recent results of inclusive top - quark pair production cross section measurements at @xmath0 and @xmath1 . 
 the results are obtained analyzing the data collected by the cms and atlas detectors at the lhc accelerator . 
 studies are performed in the dilepton channel , where the smallest uncertainty is reached , with different approaches . 
 the most precise results of both experiments are combined and confronted with the most precise theoretical calculation ( nnlo - nnll ) .