Excited fermions ate + e ? andeP colliders

Boudjema, F.; Djouadi, Abdelhak; Kneur, J.L.

doi:10.1007/bf01474339

Cited by 113 publications

(147 citation statements)

References 30 publications

Supporting

Mentioning

144

Contrasting

Unclassified

Order By: Relevance

“…Generally, composite models [12,13] assume that both left and right-handed components of excited leptons form weak isodoublets. The coupling of excited leptons to a gauge boson ( * * V) is then purely vector.…”

Section: Searches For Excited Leptonsmentioning

confidence: 99%

“…The single production crosssection and branching fractions of excited leptons are determined by the strength of the * V coupling. This interaction can be described by the following SU(2)×U(1) gauge invariant effective Lagrangian [12] where σ µν is the covariant bilinear tensor, τ denotes the Pauli matrices, Y is the weak hypercharge, W µν and B µν represent the SM gauge field tensors and the couplings g, g are the SU(2) and U(1) coupling constants of the SM. The parameter Λ which has units of energy sets the compositeness scale.…”

Section: Searches For Excited Leptonsmentioning

confidence: 99%

See 1 more Smart Citation

Search for heavy and excited leptons at LEP

Vachon

2001

Nuclear Physics B - Proceedings Supplements

View full text Add to dashboard Cite

New particle searches are ongoing at the Large Electron Positron Collider (LEP) running yearly at increasing centre-of-mass energies. The searches for heavy stable and unstable leptons performed by the four LEP experiments (ALEPH, DELPHI, L3 and OPAL) are summarised, followed by a description of the searches for excited leptons. Experimental signatures and results, including the most recent data analysed, are presented. Physics Beyond the Standard ModelAlthough very successful in describing experimental observations, the Standard Model (SM) of particle physics is however incomplete. It relies on many assumptions that cannot be explained within its framework. The search for physics beyond the SM is therefore an active field which takes on two different approaches.One approach includes models such as Grand Unified Theories (E 6 ,SO(10)...) and supersymmetry (SUSY). Within this frame work, the known SM particles are regarded as being fundamental and point-like. Some of these models predict the existence of new fundamental particles such as heavy charged (L ± ) and neutral (N) leptons.The second approach to physics beyond the SM assumes that known particles have substructure at a scale Λ > ∼ 1 TeV. Composite models could explain the number of fermion generations (or families) and the mass spectrum observed within the SM. Under the assumption of compositeness, it is natural to expect the presence of excited states of the SM fermions.With the ongoing increase in energy and luminosity at the LEP collider, new particles could be within experimental reach. Various searches are performed by the four LEP experiments. This note reviews the searches for heavy and excited leptons. Experimental signatures and results of the search for heavy stable/long-lived and unstable leptons are presented. Then, a description of the searches for single and pair production of excited leptons follows. Unless stated, the results presented here include data taken in 1999 at a centre-of-mass energy up to 202 GeV, corresponding to an integrated luminosity of about 220 pb −1 per experiment. Searches for Heavy LeptonsHeavy leptons can be sequential, mirror or vector leptons [4]. Neutral heavy leptons could, in addition, be Dirac or Majorana particles.The mixing between heavy and SM leptons is severely constrained by LEP1 data and lowenergy experiments [5]. Therefore, only the searches for pair produced heavy leptons are considered. Charged (L ± ) and neutral (N) leptons could be pair produced in e + e − collisions via the diagrams shown in Figure 1. Unstable leptons

show abstract

Section: Searches For Excited Leptonsmentioning

confidence: 99%

Section: Searches For Excited Leptonsmentioning

confidence: 99%

Search for heavy and excited leptons at LEP

Vachon

2001

Nuclear Physics B - Proceedings Supplements

View full text Add to dashboard Cite

show abstract

“…The initial state radiation e ect was included at the level of the generator for the single production, while for the double production it is taken into account in the total cross section. For excited lepton masses above the W and Z mass, the decays`!`W and`!`Z are also possible [5]. In this analysis, only the relevant electromagnetic decay of the excited lepton`!`was searched for, assuming a (1 + cos ) decay angular dependence [2], where is the angle of the nal lepton with respect to the electron beam in the`rest frame.…”

Section: Production Of Excited Leptonsmentioning

confidence: 99%

“…In this analysis, only the relevant electromagnetic decay of the excited lepton`!`was searched for, assuming a (1 + cos ) decay angular dependence [2], where is the angle of the nal lepton with respect to the electron beam in the`rest frame. The dependence of the branching ratio on the excited lepton mass was also taken into account [5]. 3 The DELPHI detector and the standard processes simulation A detailed description of the DELPHI apparatus can be found in reference [6].…”

Section: Production Of Excited Leptonsmentioning

confidence: 99%

See 1 more Smart Citation

Study of radiative leptonic events with hard photons and search for excited charged leptons at GeV

et al. 1996

View full text Add to dashboard Cite

During the last 1995 data acquisition period at LEP, the DELPHI experiment collected an integrated luminosity o f 5 : 9 p b 1 at centre-of-mass energies of 130 GeV and 136 GeV. Radiative leptonic events (e; ; ) with high energy photons were studied and compared to Standard Model predictions. The data were used to search for charged excited leptons decaying through an electromagnetic transition. No signi cant signal was found. From the search for pair produced excited leptons, the limits m e > 62:5 GeV/c 2 , m > 62:6 GeV/c 2 and m > 62:2 GeV/c 2 at 95% con dence level were established. For single excited lepton production, upper limits on the ratio =m`of the coupling of the excited charged lepton to its mass were derived.To be submitted to Phys.

show abstract

Search for unstable heavy and excited leptons in e+e− collisions at ∝s = 170-172 GeV

et al. 1998

View full text Add to dashboard Cite

We have searched for unstable neutral and charged heavy leptons, N and L ± , and for excited states of neutral and charged leptons, ν * , e * , µ * and τ * , in e + e − collisions at centre-of-mass energies of 170 and 172 GeV using the OPAL detector at LEP. No evidence for their existence was found. From the analysis of charged-current decays of pair-produced unstable heavy leptons, and of charged-current and photonic decays of pairproduced excited leptons, lower limits on their masses are derived. From the analysis of charged-current and photonic decays of singly-produced excited leptons, upper limits on the ratio of the coupling to the compositeness scale, f /Λ, are determined for masses up to the kinematic limit.

show abstract

Excited fermions ate + e ? andeP colliders

Cited by 113 publications

References 30 publications

Search for heavy and excited leptons at LEP

Search for heavy and excited leptons at LEP

Study of radiative leptonic events with hard photons and search for excited charged leptons at GeV

Search for unstable heavy and excited leptons in e+e− collisions at ∝s = 170-172 GeV

Contact Info

Product

Resources

About