Same-sign dileptons as a signature for heavy Majorana neutrinos in hadron-hadron collisions

Almeida, F.; Coutinho, Y. Amaral; Simões, J. A. Martins; Filho, P. P. Queiroz; Porto, C.M.

doi:10.1016/s0370-2693(97)00143-3

Cited by 33 publications

(33 citation statements)

References 13 publications

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“…As a result, searches for anomalous production of same-sign dileptons can be very sensitive to new physics contributions. These include supersymmetry (SUSY) [1][2][3], universal extra dimensions [4], pair production of T 5/3 particles (fermionic partners of the top quark) [5], heavy Majorana neutrinos [6], and same-sign top-pair production [7,8]. More specifically, the signature of same-sign dileptons accompanied by bottom quarks can arise from SUSY processes where third-generation quark superpartners are lighter than other squarks [9][10][11][12][13], resulting in an abundance of top and bottom quarks produced in cascade decays.…”

Section: Introductionmentioning

confidence: 99%

Search for new physics in events with same-sign dileptons and b jets in pp collisions at $ \sqrt{s}=8 $ TeV

Chatrchyan

Khachatryan

Sirunyan

et al. 2013

J. High Energ. Phys.

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A search for new physics is performed using events with isolated same-sign leptons and at least two bottom-quark jets in the final state. Results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 8 TeV with the CMS detector and corresponding to an integrated luminosity of 10.5 fb −1 . No excess above the standard model background is observed. Upper limits are set on the number of events from non-standard-model sources and are used to constrain a number of new physics models. Information on acceptance and efficiencies is also provided so that the results can be used to confront an even broader class of new physics models.

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Section: Introductionmentioning

confidence: 99%

Search for new physics in events with same-sign dileptons and b jets in pp collisions at $ \sqrt{s}=8 $ TeV

Chatrchyan

Khachatryan

Sirunyan

et al. 2013

J. High Energ. Phys.

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“…The excluded regions from LEP are based on searches for sleptons and charginos [42][43][44][45][46]. Other final states, especially the all-hadronic [22], are better suited for this standard reference model, while the leptonic same-sign final state explored in this paper is more appropriate to constrain a wide variety of other new physics models [1][2][3][4][5][6][7]. As discussed in section 4, in a general supersymmetry context, one might expect gluino-gluino or gluino-squark production to lead to same-sign dilepton events via a decay chain involving a chargino.…”

Section: Interpretation Of Resultsmentioning

confidence: 99%

“…In particular, they have been proposed as signatures of supersymmetry (SUSY) [1][2][3], universal extra dimensions [4], pair production of T 5/3 (a fermionic partner of the top quark) [5], heavy Majorana neutrinos [6], and same-sign top-pair resonances as predicted in theories with warped extra dimensions [7]. In this paper we describe searches for new physics with same-sign isolated dileptons (ee, eµ, µµ, eτ , µτ , and τ τ ), missing transverse energy (E miss T ), and hadronic jets.…”

Section: Introductionmentioning

confidence: 99%

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy at the LHC

Chatrchyan

Khachatryan

Sirunyan

et al. 2011

J. High Energ. Phys.

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Abstract:The results of searches for new physics in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state are presented. The searches use an integrated luminosity of 35 pb −1 of pp collision data at a centre-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. The observed numbers of events agree with the standard model predictions, and no evidence for new physics is found. To facilitate the interpretation of our data in a broader range of new physics scenarios, information on our event selection, detector response, and efficiencies is provided.

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“…In the general mass matrix including Dirac and Majorana fields one imposes some internal symmetry that makes the matrix singular. Then the mixing parameter has an arbitrary value, bounded only by its phenomenological consequences.Recently we have investigated this possibility for a single heavy Majorana production in hadron-hadron colliders [8]. It was shown that this mechanism is more important than pair production and that like-sign dileptons can give a clear signature for this process, even after hadronization.…”

mentioning

confidence: 99%

“…Recently we have investigated this possibility for a single heavy Majorana production in hadron-hadron colliders [8]. It was shown that this mechanism is more important than pair production and that like-sign dileptons can give a clear signature for this process, even after hadronization.…”

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confidence: 99%

Neutral heavy lepton production at next high energye+e−linear colliders

et al. 2001

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The discovery potential for detecting new heavy Majorana and Dirac neutrinos at some recently proposed high energy e + e − colliders is discussed. These new particles are suggested by grand unified theories and superstring-inspired models. For these models the production of a single heavy neutrino is shown to be more relevant than pair production when comparing cross sections and neutrino mass ranges. The process e + e − −→ ν e ± W ∓ is calculated including on-shell and off-shell heavy neutrino effects. We present a detailed study of cross sections and distributions that shows a clear separation between the signal and standard model contributions, even after including hadronization effects. The recent Super-Kamiokande results [1] provided a strong evidence for neutrino oscillations and non zero neutrino masses. This has motivated many theoretical models that imply new heavy neutrino states. These new particles are present in several grand unified extentions of the standard model such as SO (10) or E 6 . Many other new states are present in these models but neutrinos are expected to play a fundamental role in any consistent extended model. This comes mainly from the possibility that light neutrino masses can be connected to the Fermi and grand unified scales through m ν = v 2 F ermi /v GUT . This relation can be obtained from the "see-saw" mechanism with new heavy neutrino states. A fundamental point to be experimentally clarified is the Dirac or Majorana nature of neutrinos.The new heavy neutrino masses are experimentally bounded to be greater than 80-100 GeV [2,3] and the mixing with light neutrinos is expected to be small, even if there is some model dependence on these results. This means that these new neutral leptons could be detected only at the next generation of high energy colliders NLC at SLAC and TESLA at DESY. In this paper we turn our attention to these new possible lepton colliders [4]. New linear e + e − high energy colliders have been proposed, with center of mass energy from 500 GeV up to a few TeV. More recently µ + µ − and e − e − options were also proposed, as well as the electron-muon colliders.Some time ago it was noticed [5,6] that for some models the single heavy lepton production in e + e − −→ νN is higher than pair production e + e − −→ N N . Two main factors contribute for this difference. The first one is the mixing angle (s i ≡ sin θ mix ) single power in the lightto-heavy neutrino vertex, contrary to the double mixing angle power in the heavy-to-heavy neutrino vertex. The second factor is phase space suppression. If we suppose that all mixing angles are of the same order, then we have in Table I the vertices for heavy neutrino interactions in three different models [5] for new heavy neutrino states: vector singlet (VSM), vector doublet (VDM) and fermion-mirror-fermion models (FMFM). We call attention to the suppression factor for the ZN N vertex in the vector singlet model, which is not present for the other models. Throughout this paper we will suppose that mixing angles for heavy...

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Same-sign dileptons as a signature for heavy Majorana neutrinos in hadron-hadron collisions

Abstract: We discuss the possibility of same-sign dileptons as a signature for Majorana neutrinos. The production mechanism is given by a single heavy neutrino production and decay pp −→ l ± N X −→ l ± l ± X ′ . Cross section and distributions are presented for the LHC energies.

Cited by 33 publications

References 13 publications

Search for new physics in events with same-sign dileptons and b jets in pp collisions at $ \sqrt{s}=8 $ TeV

Search for new physics in events with same-sign dileptons and b jets in pp collisions at $ \sqrt{s}=8 $ TeV

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy at the LHC

Neutral heavy lepton production at next high energye+e−linear colliders

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