On measurement of top polarization as a probe of \(t\bar{t}\) production mechanisms at the LHC

DOI10.1007/JHEP11(2010)144zbMATH Open1294.81342arXiv1010.1458WikidataQ59252026 ScholiaQ59252026MaRDI QIDQ406704

Author name not available (Why is that?)

Publication date: 29 August 2014

Published in: (Search for Journal in Brave)

Abstract: In this note we demonstrate the use of top polarization in the study of

resonances at the LHC, in the possible case where the dynamics implies a non-zero top polarization. As a probe of top polarization we construct an asymmetry in the decay-lepton azimuthal angle distribution (corresponding to the sign of

c o s p h i_{e} l l

) in the laboratory. The asymmetry is non-vanishing even for a symmetric collider like the LHC, where a positive

z

axis is not uniquely defined. The angular distribution of the leptons has the advantage of being a faithful top-spin analyzer, unaffected by possible anomalous

t b W

couplings, to linear order. We study, for purposes of demonstration, the case of a

Z^{'}

as might exist in the little Higgs models. We identify kinematic cuts which ensure that our asymmetry reflects the polarization in sign and magnitude. We investigate possibilities at the LHC with two energy options:

s q r t s = 14

TeV and

s q r t s = 7

TeV, as well as at the Tevatron. At the LHC the model predicts net top quark polarization of the order of a few per cent for

M_{Z^{'}} s i m e q 1200

GeV, being as high as

10 %

for a smaller mass of the

Z^{'}

of

700

GeV and for the largest allowed coupling in the model, the values being higher for the

7

TeV option. These polarizations translate to a deviation from the standard-model value of azimuthal asymmetry of up to about

4 %

(

7 %

) for

14

(

7

) TeV LHC, whereas for the Tevatron, values as high as

12 %

are attained. For the

14

TeV LHC with an integrated luminosity of 10 fb

^{- 1}

, these numbers translate into a

3 s i g m a

sensitivity over a large part of the range

500 l e s s s i m M_{Z^{'}} l e s s s i m 1500

GeV.

Full work available at URL: https://arxiv.org/abs/1010.1458

zbMATH Keywords

No records found.

Mathematics Subject Classification ID

No records found.