The mass of the top quark is measured in a data set corresponding to 4.6 fb−1 of proton-proton collisions with centre-of-mass energy sqrt(s)=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top-antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijetproduction is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet,which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4 (stat) ±1.2 (syst) GeV.
Measurement of the Top-Quark Mass in the Fully Hadronic Decay Channel from ATLAS Data at sqrt(s) = 7 TeV
GORINI, Edoardo;PRIMAVERA, Margherita;SPAGNOLO, Stefania Antonia;VENTURA, Andrea
2015-01-01
Abstract
The mass of the top quark is measured in a data set corresponding to 4.6 fb−1 of proton-proton collisions with centre-of-mass energy sqrt(s)=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top-antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijetproduction is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet,which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4 (stat) ±1.2 (syst) GeV.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
