Measurement of the Top Quark Mass andtt¯Production Cross Section from Dilepton Events at the Collider Detector at Fermilab

Abstract

We present an analysis of dilepton events originating from tt production inpp collisions at √ s = 1.8 TeV at the Fermilab Tevatron Collider. The sample corresponds to an integrated luminosity of 109 ± 7 pb −1 . We observe 9 candidate events, with an estimated background of 2.4 ± 0.5 events. We 2 determine the mass of the top quark to be Mtop = 161 ± 17(stat.) ± 10(syst.) GeV/c 2 . In addition we measure a tt production cross section of 8.2 +4.4 −3.4 pb (where Mtop = 175 GeV/c 2 has been assumed for the acceptance estimate).PACS numbers: 14.65. Ha, 13.85.Qk, 13.85.Ni 3We report here on a measurement of the tt production cross section and top quark mass in the dilepton channel with the Collider Detector at Fermilab (CDF). The data sample corresponds to a total integrated luminosity of 109 ± 7 pb −1 . This analysis considers dilepton events originating predominantly from, with ℓ = e or µ. A subset of these events corresponding to a data sample of 67 pb −1 supported the discovery of the top quark [1,2]. Recently both the CDF and D0 collaborations have updated their measurements of the tt production cross section [3,4] and top quark mass [5,6] using the "lepton plus jets" channel: tt → W + bW −b → (ℓ + νb)(qq ′b ), with ℓ = e or µ, which has larger statistics. The consistency of the measurements presented here with those in the lepton plus jets channel is an important confirmation that these two orthogonal sets of events both originate from the same heavy top production process.A description of the CDF detector can be found in Ref. [7]. The coordinate system and various quantities used throughout this paper are defined in [8]. The momenta of the charged leptons are measured with the central tracking chamber in a 1.4-T superconducting solenoidal magnet. Electromagnetic and hadronic calorimeters surrounding the tracking chambers are used to identify and measure the energies of electrons and jets. Muons are identified with drift chambers located outside the calorimeters. A three-level trigger selects high transverse momentum (P T ) electrons and muons.The event selection is very similar to the previous analysis described in Ref. [1,9]. We require two high-P T (P T > 20 GeV/c), oppositely charged leptons (e or µ) in the central pseudorapidity region (|η| < 1.0) with at least one of them well isolated from nearby tracks and calorimeter activity. We reject Z → ℓ + ℓ − X events by requiring the dilepton invariant mass, M ee or M µµ , to be outside the interval 75-105 GeV/c 2 . If there is a high transverse energy (E T > 10 GeV) isolated photon present, the event is removed if consistent with a radiative Z decay. We also require that there be at least two jets with measured E T > 10 GeV in the pseudorapidity range |η| < 2.0, as expected from the presence of two b quarks in a tt event. The signature of the two neutrinos in the decay is missing energy transverse to the beam direction ( / E T ); we require | / E T | > 25 GeV. The / E T is corrected for non-uniformities in calorimeter response and absolute energy scale, and for ...

Measurement of the $ {{\rm t}\bar{\rm t}} $ production cross section and the top quark mass in the dilepton channel in pp collisions at $ \sqrt {s} = 7 $ TeV

“…The Matrix Weighting Technique (MWT) [13] was one approach used in the first measurements with this channel [13,49]. Other approaches were developed later, for example the fully kinematic method (KIN) [12].…”

Measurement of the top-quark mass in $\mathrm{t}\overline{\mathrm{t}}$ events with dilepton final states in pp collisions at $\sqrt{s}=7\ \mbox{TeV}$

“…We use an improved version of the Matrix Weighting Technique (MWT) [31] that was used in the first measurements in this channel [31,32]. The algorithm is referred to as the analytical MWT (AMWT) method.…”

Universal Extra Dimensions

“…For the decay into the W bosons, the signal is similar to the top quark. One can use the measurements of the top quark production cross section at the Tevatron [20,21] and 199 GeV if the branching ratio is 100% [23]. This can also apply to the KK states of the b quark.…”