Title: Seeking for sterile neutrinos with displaced leptons at the LHC

Abstract

We study the signal of long-lived sterile neutrino at the LHC produced through the decay of the W boson. It decays into charged lepton and jets. The characteristic signature is a hard prompt lepton and a lepton from the displaced decay of the sterile neutrino, which leads to a bundle of displaced tracks with large transverse impact parameter. Different from other studies, we neither reconstruct the displaced vertex nor place requirement on its invariant mass to maintain sensitivity for low sterile neutrino masses. Instead, we focus on the displaced track from the lepton. A difficulty for low mass sterile neutrino study is that the displaced lepton is usually non-isolated.Therefore, leptons from heavy flavor quark is the major source of background. We closely follow a search for displaced electron plus muon search at CMS and study their control regions, which is related to our signal regions, in great detail to develop a robust estimation of the background for our signals. After further optimization on the signal limiting the number of jets, low H _T and large lepton displacement d ₀ to suppress SM background, we reach an exclusion sensitivity of about 10 ^-8 (10 ^-5) for the mixing angle square atmore » 10 (2) GeV sterile neutrino mass respectively. Thestrategy we propose can cover the light sterile masses complimentary to beam dumpand forward detector experiments« less

Authors:

Liu, Jia ^[1]; Liu, Zhen ^[2]; Wang, Lian-Tao ^[3]; Wang, Xiao-Ping ^[4]

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+ Show Author Affiliations

1. Univ. of Chicago, IL (United States). Enrico Fermi Inst.
2. Univ. of Maryland, College Park, MD (United States)
3. Univ. of Chicago, IL (United States). Enrico Fermi Inst., and Kavli Inst. for Cosmological Physics
4. Argonne National Lab. (ANL), Argonne, IL (United States)

Publication Date:

2019-07-26

Research Org.:

Univ. of Chicago, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

OSTI Identifier:

1593919

Grant/Contract Number:  

SC0009924

Resource Type:

Accepted Manuscript

Journal Name:

Journal of High Energy Physics (Online)

Additional Journal Information:

Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2019; Journal Issue: 7; Journal ID: ISSN 1029-8479

Publisher:

Springer Berlin

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Beyond Standard Model; Neutrino Physics