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6 pages, 337 KiB

Open AccessArticle

Heavy Neutral Lepton Search and μ → eγ Constraints in Case of Type-I Seesaw

by Stefano Morisi

Symmetry 2024, 16(7), 843; https://doi.org/10.3390/sym16070843 - 4 Jul 2024

Cited by 3 | Viewed by 968

Within the type-I seesaw mechanism, it is possible to have large (order one) light–heavy neutrino mixing even in the case of low right-handed neutrino mass scale (of the order of GeV). This implies large lepton flavor violation. As an example, we consider the [...] Read more.

μ \to e γ

that can have a branching of up to

10^{- 8}

within type-I seesaw (in contrast with the tiny value

10^{- 54}

expected). Such an enhancement of lepton flavor violation can be used to constraint the parameter space of long-lived particle experiments. Full article

(This article belongs to the Special Issue Symmetry and Neutrino Physics: Theory and Experiments)

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6 pages, 1846 KiB

Open AccessProceeding Paper

Beyond the Standard Model New Physics Searches with SBND

by Supraja Balasubramanian

Phys. Sci. Forum 2023, 8(1), 68; https://doi.org/10.3390/psf2023008068 - 8 Nov 2023

Cited by 1 | Viewed by 1174

Abstract

SBND (Short-Baseline Near Detector) is a 112-ton liquid argon time projection chamber located on the Booster Neutrino Beam at Fermi National Accelerator Laboratory, and is the near detector of the Short-Baseline Neutrino program. The primary goals of SBND are to provide flux constraints for sterile neutrino searches, conduct world-leading neutrino cross-section measurements on argon, and perform Beyond the Standard Model (BSM) new physics searches with its high-precision particle identification capabilities. SBND’s prospects and tools for detecting a variety of BSM phenomena produced in a neutrino beam, such as sub-GeV dark matter, dark neutrinos, heavy neutral leptons and millicharged particles, are discussed. Full article

(This article belongs to the Proceedings of The 23rd International Workshop on Neutrinos from Accelerators)

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22 pages, 1233 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Detecting Heavy Neutral SUSY Higgs Bosons Decaying to Sparticles at the High-Luminosity LHC

by Howard Baer, Vernon Barger, Xerxes Tata and Kairui Zhang

Symmetry 2023, 15(2), 548; https://doi.org/10.3390/sym15020548 - 18 Feb 2023

Cited by 6 | Viewed by 2228

Abstract

In supersymmetry (SUSY) models with low electroweak naturalness (natSUSY), which have been suggested to be the most likely version of SUSY to emerge from the string landscape, higgsinos are expected at the few hundred GeV scale, whilst electroweak gauginos inhabit the TeV scale. [...] Read more.

H, A

are gaugino plus higgsino provided these decays are kinematically open. The light higgsinos decay to soft particles, so are largely invisible, whilst the gauginos decay to W, Z or h plus missing transverse energy (

\frac{E}{T}

). Thus, we examine the viability of

H, A \to W + \frac{E}{T}

Z + \frac{E}{T}

and

h + \frac{E}{T}

signatures at the high luminosity LHC (HL-LHC) in light of large standard model (SM) backgrounds from (mainly)

t \bar{t}

V V

and

V h

production (where

V = W, Z

). We also examine whether these signal channels can be enhanced over backgrounds by requiring the presence of an additional soft lepton from the decays of the light higgsinos. We find significant regions in the vicinity of

m_{A} \sim 1 - 2

TeV of the

m_{A}

vs.

tan β

plane, which can be probed at the high luminosity LHC, using these dominant signatures by HL-LHC at

5 σ

and at the 95% confidence level (CL). Full article

(This article belongs to the Special Issue Supersymmetry with Higgs Bosons Research)

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19 pages, 1718 KiB

Open AccessReview

Charged Lepton Flavor Violation at the High-Energy Colliders: Neutrino Mass Relevant Particles

by Yongchao Zhang

Universe 2022, 8(3), 164; https://doi.org/10.3390/universe8030164 - 6 Mar 2022

Cited by 1 | Viewed by 2982

Abstract

We summarize the potential charged lepton flavor violation (LFV) from neutrino mass relevant models, for instance the seesaw mechanisms. In particular, we study, in a model-dependent way, the LFV signals at the high-energy hadron and lepton colliders originating from the beyond standard model [...] Read more.

H^{\pm \pm}

, heavy neutrino N, heavy

W_{R}

boson, and the

Z^{'}

boson. For the neutral scalar, doubly charged scalar and

Z^{'}

boson, the LFV signals originate from the (effective) LFV couplings of these particles to the charged leptons, while for the heavy neutrino N and

W_{R}

boson, the LFV effects are from flavor mixing in the neutrino sector. We consider current limits on these BSM particles and estimate their prospects at future high-energy hadron and lepton colliders. Full article

(This article belongs to the Special Issue Charged Lepton Flavor Violation)

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10 pages, 2180 KiB

Open AccessArticle

Search for Exotic Particles at the NA62 Experiment

by Maria Brigida Brunetti, Francesco Gonnella, Lorenza Iacobuzio and On behalf of the NA62 Collaboration

Universe 2018, 4(11), 119; https://doi.org/10.3390/universe4110119 - 7 Nov 2018

Cited by 1 | Viewed by 3169

Abstract

The NA62 experiment at the CERN Super Proton Synchrotron (SPS) is currently taking data to measure the ultra-rare decay

K^{+} \to π^{+} ν \bar{ν}

. The high-intensity setup, trigger flexibility, detector performance and high-efficiency vetoes make NA62 also suitable for [...] Read more.

The NA62 experiment at the CERN Super Proton Synchrotron (SPS) is currently taking data to measure the ultra-rare decay

K^{+} \to π^{+} ν \bar{ν}

. The high-intensity setup, trigger flexibility, detector performance and high-efficiency vetoes make NA62 also suitable for direct searches of long-lived, beyond-the-Standard-Model particles, such as Heavy Neutral Leptons (HNLs), Axion-Like Particles (ALPs) and Dark Photons (DPs); moreover, many rare and forbidden decays are studied at NA62. The status of all these searches is reviewed, together with prospects for future data taking at NA62 after the CERN Long Shutdown 2 (LS2). Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference on New Frontiers in Physics (ICNFP 2018))

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