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A search is performed for a heavy Majorana neutrino (N), produced by leptonic decay of a W boson propagator and decaying into a W boson and a lepton, with the CMS detector at the LHC. The signature used in this search consists of two…

High Energy Physics - Experiment · Physics 2019-01-25 CMS Collaboration

We investigate mixing of neutrinos in the $\nu$MSM (neutrino Minimal Standard Model), which is the MSM extended by three right-handed neutrinos. Especially, we study elements of the mixing matrix $\Theta_{\alpha I}$ between three…

High Energy Physics - Phenomenology · Physics 2011-04-08 Takehiko Asaka , Shintaro Eijima , Hiroyuki Ishida

The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter-antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from…

High Energy Physics - Experiment · Physics 2025-08-29 ATLAS Collaboration

Relying upon the usefulness of the \mu-\tau symmetry, we find a new type of neutrino mass texture with a single phase parameter \delta that describes maximal atmospheric neutrino mixing and Dirac CP violation due to the presence of \delta.…

High Energy Physics - Phenomenology · Physics 2014-11-18 Ichiro Aizawa , Masaki Yasue

We consider a mechanism for neutrino mass generation, based on a local B-L extension of the standard model, which becomes a linear seesaw regime for light neutrinos after spontaneous symmetry breaking. The spectrum of extra particles…

High Energy Physics - Phenomenology · Physics 2014-12-10 Claudio O. Dib , Gaston R. Moreno , Nicolas A. Neill

A search for heavy Majorana neutrinos in events containing a pair of high-$p_{\mathrm{T}}$ leptons of the same charge and high-$p_{\mathrm{T}}$ jets is presented. The search uses $20.3 \mathrm{fb}^{-1}$ of $pp$ collision data collected with…

High Energy Physics - Experiment · Physics 2015-08-14 ATLAS Collaboration

It is well-known that thermal leptogenesis through the decays of the lightest right-handed neutrinos encounters serious difficulties when SO(10)-inspired mass conditions are imposed on the Dirac neutrino mass matrix and light neutrino…

High Energy Physics - Phenomenology · Physics 2009-02-02 Pasquale Di Bari , Antonio Riotto

A search for heavy right-handed Majorana or Dirac neutrinos $N_R$ and heavy right-handed gauge bosons $W_R$ is performed in events with a pair of energetic electrons or muons, with the same or opposite electric charge, and two energetic…

High Energy Physics - Experiment · Physics 2019-01-23 ATLAS Collaboration

Recently we proposed a model for light Dirac neutrinos in which two right-handed (RH) neutrinos per generation are added to the particles of the Standard Model (SM), implemented with the symmetry of fermionic contents. The ordinary one is…

High Energy Physics - Phenomenology · Physics 2015-10-23 Ernesto A. Matute

We study the possibility of generating non-zero reactor mixing angle $\theta_{13}$ and baryon asymmetry of the Universe within the framework of an $A_4$ flavour symmetric model. Using the conventional type I seesaw mechanism we construct…

High Energy Physics - Phenomenology · Physics 2018-06-13 Debasish Borah , Mrinal Kumar Das , Ananya Mukherjee

The symmetry breaking of left right symmetric model around few TeV range permits the existence of massive right handed neutrinos or gauge bosons. In this work the decay of lightest right handed neutrinos in a class of minimal left right…

High Energy Physics - Phenomenology · Physics 2020-10-06 Anupam Yadav , Sabeeha Naaz , Jyotsna Singh , R. B. Singh

A gauged $U(1)_X$ extension of the Standard Model is a simple and consistent framework to naturally incorporate three right-handed neutrinos (RHNs) for generating the observed light neutrino masses and mixing by the type-I seesaw mechanism.…

High Energy Physics - Phenomenology · Physics 2019-11-13 Arindam Das , P. S. Bhupal Dev , Nobuchika Okada

A detailed analysis of ZZ production at the upgraded Fermilab Tevatron and the CERN Large Hadron Collider is presented for general ZZZ and ZZ\gamma couplings. Deviations from the Standard Model gauge theory structure for each of these can…

High Energy Physics - Phenomenology · Physics 2014-11-17 U. Baur , D. Rainwater

We show that in theories where neutrino masses arise from type I seesaw formula with three right handed neutrinos and where large atmospheric mixing angle owes its origin to an approximate leptonic $\mu-\tau$ interchange symmetry, the…

High Energy Physics - Phenomenology · Physics 2008-11-26 R. N. Mohapatra , S. Nasri , Haibo Yu

Seesaw models with a small lepton number breaking can naturally accommodate electroweak-scale pseudo-Dirac neutrinos with a sizable mixing with the active neutrinos, while satisfying the light neutrino oscillation data. Due to the smallness…

High Energy Physics - Phenomenology · Physics 2014-07-29 Arindam Das , P. S. Bhupal Dev , Nobuchika Okada

There are no upper limits on the possible number of massive, singlet (right--handed) neutrinos that may participate in the seesaw mechanism, and some string constructions motivate seesaw models with up to O(100) right--handed neutrinos. In…

High Energy Physics - Phenomenology · Physics 2008-11-26 John Ellis , Oleg Lebedev

A comprehensive study of the effect of an unstable tau neutrino on primordial nucleosynthesis is presented. The standard code for nucleosynthesis is modified to allow for a massive decaying tau neutrino whose daughter products include…

Astrophysics · Physics 2008-11-26 S. Dodelson , G. Gyuk , M. S. Turner

We examine constraints on a model with pure right-handed third generation charged couplings. The parameters of the right-handed mixing matrix and the right-handed coupling strength are constrained from semi-leptonic B decays, the mass…

High Energy Physics - Phenomenology · Physics 2009-10-31 Adam Lewandowski

Our present work explores the possibility of neutrino mass generation through {\em Type-I see-saw} mechanism and provides an explanation of the baryon asymmetry of the Universe via thermal leptogenesis in the framework of $Z_3$-symmetric…

High Energy Physics - Phenomenology · Physics 2020-09-08 Indrani Chakraborty , Himadri Roy

The Majorana nature of neutrinos can be experimentally verified only via {\it lepton-number} violating processes involving charged leptons. We study 36 lepton-number violating ($\lv$) processes from the decays of tau leptons and…

High Energy Physics - Phenomenology · Physics 2015-03-13 Anupama Atre , Tao Han , Silvia Pascoli , Bin Zhang