Related papers: Helicity Amplitudes for Single-Top Production
In this paper, I study final state QCD radiative corrections to off-shell single top production via decaying $W$ at hadron collider energies. The tree level Breit-Wigner distribution of the produced top invariant mass is distorted by final…
We review recent measurements of the properties of the top quark by the CDF and D0 experiments: the mass and decay width of the top quark, the ratio $R=\btwb/\btwq$, the total production cross section of \ttbar\ pairs, the helicity of the…
The production of four top quarks is a rare process in the Standard Model that provides unique opportunities and sensitivity to Standard Model observables including potential enhancement from many popular new physics extensions. This…
Extensions of the standard model that include new W bosons or extended technicolor gauge bosons can predict sizeable changes in the rate of single top quark production, even when constrained to be consistent with precision electroweak data.…
With data collected during the first half of 2011 pp run of the Large Hadron Collider at \surds = 7 TeV, a substantial data sample of high p_T triggers, 1.08/fb, has been collected by the ATLAS detector. Measurements of the production of…
The large data samples of thousands of top events collected at the Tevatron experiments CDF and D0 allow for a variety of measurements to analyze the properties of the top quark. Guided by the question "Is the top quark observed at the…
We consider single-top-quark production via the weak process $q\bar q to t\bar b$ at hadron colliders. This process may provide the best measurement of the magnitude of the Cabbibo-Kobayashi-Maskawa matrix element $V_{tb}$. We show that a…
We study effects of beyond the Standard Model physics coupling third generation quarks to leptons of the first two generations. We parametrize these effects by dimension-six effective operators, and we also consider related simplified UV…
Knowledge of two-loop QCD amplitudes for processes $q\bar q \to V_1 V_2 \to (l_1\bar l'_1)(l_2 \bar l'_2)$ is important for improving the theoretical description of four-lepton production in hadron collisions. In this paper we compute these…
We present a fully analytic calculation of the leading-order one-loop amplitude for triple Higgs production via gluon fusion, $gg \to HHH$, retaining full dependence on the mass of the heavy quark circulating in the loop. This amplitude…
The W-boson helicity fractions in top-quark decays are measured with ttbar events in the lepton+jets final state, using proton-proton collisions at a centre-of-mass energy of 7 TeV, collected in 2011 with the CMS detector at the LHC. The…
Measurements of single top quark production are presented, performed using CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV. The cross sections for the electroweak production of single top quarks in the…
We compute the four-quark plus three-gluon and six-quark plus one-gluon tree level amplitudes using on-shell recursion relations. They are needed for the calculation of the 5-jet cross-section at the Born level, and constitute an essential…
We use the transverse momentum spectrum of leptons in the decay chain t-->bW with W-->l nu to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a ttbar sample isolated in 106 +/- 4 inverse picobarns of…
We present the two-loop QCD corrections to the amplitude of the Higgs production associated with a $Z$ boson via the bottom quark-antiquark annihilation channel with a non-vanishing bottom-quark Yukawa coupling. The computation is performed…
We investigate the prospect of the LHC for discovering new physics effects via new strategies in the same-sign top pair and same-sign top pair associated with a $W$ boson signatures. Significant enhancement in production of same-sign top…
Due to its high mass top quarks decay before top-flavoured hadrons can be formed. This feature yields experimental access to the top quark polarization and production asymmetries. The large top quark sample moreover enables measurements of…
We present the gluon-gluon and photon-gluon helicity amplitudes for color singlet and octet charmonium production in polarized and unpolarized hadron-hadron and photon-hadron collisions.
In this paper, we examine the sensitivity of the three-top quark production at the LHC to the top quark flavor-changing neutral currents (FCNC) as well as the sensitivity of the four-top production to the strong and weak dipole moments of…
We calculate squared helicity amplitudes for non-diagonal and mixed squark pair production at hadron colliders, taking into account not only loop-induced QCD diagrams, but also previously unconsidered electroweak channels, which turn out to…