Search for The charge asymmetry in top anti-top resonance Smail BELAAOUJARajaa CHERKAOUI ELMOURSLI Marcel VOS UniversityMohmed V Faculty of sciences Nuclear laboratory Workshop, rabat october 2010

contents The charge asymmetry at HC Top quark asymmetry at Tevatron Top quark asymmetry at LHC The top quark charge asymmetry Beyond the SM MadGraph Generator Charge asymmetry study for resonance spin1 color singlet Charge asymmetry study for resonance spin1 color octet Conclusion and perspective

The charge asymmetry at HC QCD prediction: – At tree level, tt~pair production at HC is charge symmetric. – But at Ο(α s 3 ) order tt~ pair production is a charge asymmetic

Graphs originated by that contribute to the QCD charge asymmetry in quark-antiquark production

Is The asymmetry a CP violation? The asymmetry appears in a restriction of phase space The charge asymmetric defined as: N t ( cosθ ): number of top quark produced in an angle θ N tbar ( cosθ ): number of anti-top quark produced in an angleθ CP invariance the asymmetry is equivalent to Forward-backwards asymmetry

Top quark asymmetry at Tevatron ( ) Lepton+jet channel energy With luminosity of 3.2 fb -1 The total charge asymmety generated at the tevatron by QCD at NLO :

Top quark asymmetry at LHC ( ) The production cross section of top quarks is, dominated by gluon-gluon fusion gluon-gluon fusion represents the 84% of the top quark at 10TeV and 90% at 14TeV The charge aymmetry generated from the qqbar and qg is small in the most of kinimatics phase space

The top quark charge asymmetry Beyond the SM: topBSM The topBSM is implemented to study BSM effects in the ttbar invariant mass spectrum This model includes some number of resonances states which there are production of an intermediate particle X that decaying into ttbar:

This model includes the following possible resonances in the ttbar spectrum: o spin-0, color singlet =higgs-like particule couples only to quarks o spin-0, color octet = is a scalar, colored particle that couples only to top quarks o spin-1, color singlet = similar to the SM Z boson o spin-1, color octet = similar to a heavy gluon o spin-2, ADD model = graviton particle of the large extra dimensions model o spin-2, RS model The top quark charge asymmetry Beyond the SM: topBSM

Charge asymmetry study for resonances spin1 color singlet and spin1 color octet that produce the top anti-top quarks Tool used : MadGraph generator

MadGraph generator The MadGraph generator allows to: Generates the process Make the Faymann diagrams Calculate the amplitude of helicity

MadGraph characteristics Both for SM as well as BSM Easy to implement new models Can generate multiple process in the same run Decay chains specifications Call for the pythia package (hadronization) and PGS (detector sim) for a full simulation Web server interface from which the simulation itself can be done on-line or off-line Can create root files at each stape

MadGraph structure

Charge asymmetry study for resonance spin1 color singlet In this resonance state, the particule X(spin1 color singlet) is a similar to the SM Z boson The process generated: With elimination of o1 resonance and coupling to the gluons √ś=7TeV

Top quark Anti-top quark For the asymetry is more importante Top anti-top Asymmetry

A= Top distribution with cut on η: anti-top distribution with cut on η:

Leptons Asymmetry mu- mu+

A= distribution with cut on η:

Cut on the invariant mass with Resonance S1 mtt > 500 GeVmtt > 700 GeVmtt > 1000 GeV

In this resonance state the particule X(spin1 color octet) is a similar to a heavy gluon, it has the same couplings as the gluon The process generated: We have exclued the s1 resonance, the photons, the gluons and the Z boson √ś=7TeV Charge asymmetry study for resonance spin1 color octet

Top anti-top Asymetry Top quark Anti-top quark

A= anti-top distribution with cut on η: Top distribution with cut on η:

A=-0, distribution with cut on η:

Resonance O1 mtt > 500 GeVmtt > 700 GeVmtt > 1000 GeV Cut on the invariant mass with

Conclusion and perspective The value of the asymmetry deponds on the cut on the invaraint mass The results are significante Futur work: generate samples of heavy color octet resonances decaying to ttbar with arbitrary vector and axial-vector couplings to quark(fully leptonic channel):

Reference Paola ferrario Tesis docttoral,July G. L.Strycheckr et al. [CDF Cllaboration],Conf. Note 9724 (march2009). O. Antunano, J. H. Kuhn and G. Rodrigo, Phys. Rev. D (2008). G. Rodrigo, PoS RADCOR (2008). [arXiv: [hep-ph]].

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