Göttingen 2012 – scientific programme

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T: Fachverband Teilchenphysik

T 37: Top-Quark: Eigenschaften 1

T 37.5: Talk

Monday, February 27, 2012, 17:45–18:00, ZHG 105

Evaluation of systematic uncertainties on m_top from initial and final state radiation using the novel φ^* observable in Z→ℓℓ events — •Oleg Brandt, Arnulf Quadt, and Elizaveta Shabalina — II. Physikalisches Insitut, Georg-August-Universität Göttingen

To achieve the smallest systematic uncertainty possible for the final, most precise single measurement of m_top with the DØ detector, we capitalise on the advantage of the initial state at the Fermilab’s Tevatron collider over that provided by the CERN’s LHC, which features notably higher initial state radiation rates. Moreover, due to the dominance of quark-antiquark annihilation in production of t t pairs at the Tevatron, the rate of initial state radiation can be extrapolated to final state radiation.

We use unfolded distributions in φ^* at different Q², extracted from 7.3 fb⁻¹ of Z→ℓℓ events recorded by DØ, to evaluate systematic uncertainties on m_top from initial and final state radiation. φ^* is a novel topological variable, which offers superb sensitivity to the transverse momentum of the Z boson at the lower end of the spectrum compared to conventional observables. Besides the m_top measurement, our studies are relevant and beneficial for the majority of analyses in the top sector at the Tevatron, and can possibly be extended to the final state radiation at the LHC.