Heavy neutral fermions at the high-luminosity LHC

Helo, Juan Carlos; Hirsch, Martin; Wang, Zeren Simon

doi:10.1007/jhep07(2018)056

Cited by 103 publications

(114 citation statements)

References 47 publications

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“…Although the LLP models considered here are among the most widely discussed, it is important to note that they do not exhaust the full physics potential of the detectors. In particular, FASERs discovery potential has already been discussed in other new physics models, including inelastic dark matter [34], R-parity violating supersymmetry [29,35], models with strongly interacting massive particles (SIMPs) [33], and twin Higgs scenarios [31]. In addition, when more complete models of BSM physics are considered, it is often natural that more than one new light particle can appear, e.g., both a dark photon and a dark Higgs boson, leading to opportunities to simultaneously discovery more than one new particle in FASER and FASER 2.…”

Section: Discussionmentioning

confidence: 99%

“…POT collected in 5 years of operation [20]; the LHC searches for a prompt lepton plus a single displaced lepton jet for √ s = 13 TeV and 300 fb −1 of integrated luminosity [82] (see also Ref. [83] for sensitivity in displaced vertex searches at LHCb); the proposed MATHUSLA experiment assumes a large-scale 200 m × 200 m × 20m detector located on the surface above ATLAS or CMS and operating during the HL-LHC era to collect full 3 ab −1 of integrated luminosity [22]; and the proposed CODEX-b detector assumes a 10 m × 10 m × 10m fiducial volume close to LHCb and 300 fb −1 to be collected by the HL-LHC [29,37]. For the ν τ mixing scenario, one of the future projected limits comes from searches for τ production in B factories like Belle-II, with their subsequent decay into Fig.…”

Section: Faser Reach For Heavy Neutral Leptonsmentioning

confidence: 99%

“…However, it is also important to quantify FASER's reach relative to existing constraints, as well as to compare FASER to the many other complementary experiments with similar physics targets, including HPS [13], Belle-II [14], LHCb [15,16], NA62 [17], NA64 [18], SeaQuest [19], SHiP [20], MATHUSLA [21,22], CODEX-b [23], AL3X [24], LDMX [25], and others mentioned below. For this, it is necessary to evaluate FASER's sensitivity in specific models [7,[26][27][28][29][30][31][32][33][34][35]. In this study, we determine the sensitivity reach of both FASER and FASER 2 for a wide variety of proposed particles, updating previous results to a uniform set of detector assumptions, and analyzing new models.…”

mentioning

confidence: 99%

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FASER’s physics reach for long-lived particles

Ariga¹,

Ariga²,

Boyd³

et al. 2019

Phys. Rev. D

332

330

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FASER, the ForwArd Search ExpeRiment, is an approved experiment dedicated to searching for light, extremely weakly-interacting particles at the LHC. Such particles may be produced in the LHC's high-energy collisions and travel long distances through concrete and rock without interacting. They may then decay to visible particles in FASER, which is placed 480 m downstream of the ATLAS interaction point. In this work we briefly describe the FASER detector layout and the status of potential backgrounds. We then present the sensitivity reach for FASER for a large number of long-lived particle models, updating previous results to a uniform set of detector assumptions, and analyzing new models. In particular, we consider all of the renormalizable portal interactions, leading to dark photons, dark Higgs bosons, and heavy neutral leptons (HNLs); light B−L and L i −L j gauge bosons; axion-like particles (ALPs) that are coupled dominantly to photons, fermions, and gluons through non-renormalizable operators; and pseudoscalars with Yukawa-like couplings. We find that FASER and its follow-up, FASER 2, have a full physics program, with discovery sensitivity in all of these models and potentially far-reaching implications for particle physics and cosmology.

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Section: Discussionmentioning

confidence: 99%

Section: Faser Reach For Heavy Neutral Leptonsmentioning

confidence: 99%

mentioning

confidence: 99%

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FASER’s physics reach for long-lived particles

Ariga¹,

Ariga²,

Boyd³

et al. 2019

Phys. Rev. D

332

330

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show abstract

“…The sensitivity reach of FASER has been investigated for a large number of new physics scenarios [78][79][80][81][82][83][84][85][86][87][88][89]. FASER will have the potential to discover a broad array of new particles, including dark photons, other light gauge bosons, heavy neutral leptons with dominantly τ couplings, and axion-like particles.…”

Section: Fasermentioning

confidence: 99%

Physics beyond colliders at CERN: beyond the Standard Model working group report

Beacham

Burrage

Curtin

et al. 2019

J. Phys. G: Nucl. Part. Phys.

488

628

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The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics.ii 7 Physics reach of PBC projects 66 8 Physics reach of PBC projects in the sub-eV mass range 66 8.1 Axion portal with photon dominance (BC9) 66 9 Physics reach of PBC projects in the MeV-GeV mass range 73 9.1 Vector Portal 78 9.1.1 Minimal Dark Photon model (BC1) 78 9.1.2 Dark Photon decaying to invisible final states (BC2) 83 9.1.3 Milli-charged particles (BC3) 90 9.2 Scalar Portal 93 9.2.1 Dark scalar mixing with the Higgs (BC4 and BC5) 93 9.3 Neutrino Portal 97 9.3.1 Neutrino portal with electron-flavor dominance (BC6) 98 9.3.2 Neutrino portal with muon-flavor dominance (BC7) 101 9.3.3 Neutrino portal with tau-flavor dominance (BC8) 103 9.4 Axion Portal 106 9.4.1 Axion portal with photon-coupling (BC9) 106 9.4.2 Axion portal with fermion-coupling (BC10) 110 9.4.3 Axion portal with gluon-coupling (BC11) 113 10 Physics reach of PBC projects in the multi-TeV mass range 115 10.1 Measurement of EDMs as probe of NP in the multi TeV scale 115 10.2 Experiments sensitive to Flavour Violation 116 10.3 B physics anomalies and BR(K → πνν) 120 11 Conclusions and Outlook 121 A ALPS: prescription for treating the FCNC processes 123 B ALPs: production via π 0 , η, η mixing 126 Executive SummaryThe main goal of this document follows very closely the mandate of the Physics Beyond Colliders (PBC) study group, and is "an exploratory study aimed at exploiting the full scientific potential of CERN's accelerator complex and its scientific infrastructure through projects complementary to the LHC, HL-LHC and other possible future colliders. These projects would target fundamental physics questions that are similar in spirit to those addressed by high-energy colliders, but that require different types of beams and experiments 1 ". Fundamental questions in modern particle physics as the origin of the neutrino masses and oscillations, the nature of Dark Matter and the explanation of the mechanism that drives the baryogenesis are still open today and do require an answer.So far an unambiguous signal of New Physics (NP) from direct searches at the Large Hadron Collider (LHC), indirect searches in flavour physics and direct detection Dark Matter experiments is absent. Moreover, theory provides no clear guidance on the NP scale. This imposes today, more than ever, a broadening of the experimental effort in the quest for NP. We need to explore different ranges of interaction strengths and masses with respect to what is already covered by existing or planned initiatives.Low-mass and very-weakly coupled particles represent an attractive possibility, theoretically and phenomenologically well motivated, but currently poorly explored: a systematic investigation should be pursued in the next decades both at acc...

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“…Furthermore, in the mass range of GeV to 100 GeV, the sterile neutrino would be metastable or long-lived at the detector scale, and can be probed at beam-dump types of experiments [27][28][29][30][31][32][33][34][35][36][37][38][39] (see also a review [40]), Very recently, the searches for sterile neutrino at the LHC started to develop actively as part of the long-lived particles searches covering the GeV scale [3,[41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57].…”

mentioning

confidence: 99%

Seeking for sterile neutrinos with displaced leptons at the LHC

Liu

Wang

et al. 2019

J. High Energ. Phys.

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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 at 10 (2) GeV sterile neutrino mass respectively. The strategy we propose can cover the light sterile masses complimentary to beam dump and forward detector experiments.

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Heavy neutral fermions at the high-luminosity LHC

Cited by 103 publications

References 47 publications

FASER’s physics reach for long-lived particles

FASER’s physics reach for long-lived particles

Physics beyond colliders at CERN: beyond the Standard Model working group report

Seeking for sterile neutrinos with displaced leptons at the LHC

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