<p>We study the complementarity between COHERENT and LHC searches in testing neutrino nonstandard interactions (NSIs) through the completion of the effective field theory approach within a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> simplified model. Our results show that LHC bounds are strongly dependent on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> mass, with relatively large masses excluding regions in the parameter space that are allowed by COHERENT data and its future expectations. We demonstrate that the combination of low- and high-energy experiments results in a viable approach to break NSI degeneracies within the context of simplified models.</p>

Spain

Víctor Martín Lozano

G. Sanchez Garcia

Adrián Terrones

Neutrino nonstandard interactions: Confronting COHERENT and LHC data

<p>Weakly interacting massive particles (WIMPs) constitute a paradigm in the search for particle dark matter. In contrast to supersymmetry (SUSY), we explore the possibility that WIMP dark matter acts as mediator of neutrino mass generation. We examine in detail the phenomenology of fermionic dark matter in the revamped (or singlet-triplet) scotogenic model and study its collider implications. Unlike SUSY WIMP dark matter, collider searches for the lightest scotogenic particle at LHC/LHC-HL are strongly complementary to charged lepton flavor violation probes and dark matter studies.</p>

J.W.F. Valle

Collider signatures of fermionic scotogenic dark matter

Leptoquarks are theorized particles of either scalar or vector nature that couple simultaneously to quarks and leptons. Motivated by recent measurements of coherent elastic neutrino-nucleus scattering, we consider the impact of scalar leptoquarks coupling to neutrinos on a few complementary processes, from low energy to colliders. In particular, we set competitive constraints on the typical mass and coupling of scalar leptoquarks by analyzing recent COHERENT data. We compare these constraints with bounds from atomic parity violation experiments, deep inelastic neutrino-nucleon scattering and collider data. Our results highlight a strong complementarity between different facilities and demonstrate the power of coherent elastic neutrino-nucleus scattering experiments to probe leptoquark masses in the sub-TeV range. Finally, we also present prospects for improving current bounds with future upgrades of the COHERENT detectors and the planned European Spallation Source.

Valentina De Romeri

Neutrino window to scalar leptoquarks: From low energy to colliders

Several hints of the presence of a new state at about 95 GeV have been observed recently. The CMS and ATLAS Collaborations have reported excesses in the diphoton channel at about this diphoton invariant mass with local statistical significances of <math><mn>2.9</mn><mi>σ</mi></math> and <math><mn>1.7</mn><mi>σ</mi></math>, respectively. Furthermore, a <math><mn>2</mn><mi>σ</mi></math> excess in the <math><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> final state was also observed at LEP, again pointing at a similar mass value. We interpret these intriguing hints of new physics in a variant of the Scotogenic model, an economical scenario that induces Majorana neutrino masses at the loop level and includes a viable dark matter candidate. We show that our model can explain the 95 GeV excesses while respecting the relevant collider, Higgs, and electroweak precision bounds and discuss other phenomenological features of our scenario.

Pablo Escribano

Avelino Vicente

Scotogenic explanation for the 95 GeV excesses

A final state consisting of one charged lepton, at least one jet, and little missing transverse energy can be a very promising signature of new physics at the LHC across a wide range of models. However, it has received only limited attention so far. In this work we discuss the potential sensitivity of this channel to various new physics scenarios. To demonstrate our point, we consider its application to lepton parton distribution functions (PDFs) at the LHC in the context of supersymmetry. These lepton PDFs can lead to resonant squark production (similar to leptoquarks) via lepton number violating couplings present in <math><mi>R</mi></math>-parity violating supersymmetry (RPV-SUSY). Unlike leptoquarks, in RPV-SUSY there are many possible decay modes leading to a wide range of signatures. We propose two generic search regions: (a) a single first or second generation charged lepton, exactly 1 jet and low missing transverse energy, and (b) a single first or second generation charged lepton, at least 3 jets, and low missing transverse energy. We demonstrate that together these cover a large range of RPV-SUSY signatures, and have the potential to perform better than existing low-energy bounds, while being general enough to extend to a wide range of possible models hitherto not explored at the LHC.

Germany

Herbi K. Dreiner

Saurabh Nangia

United States

CERN

Toby Opferkuch

Lepton PDFs and multipurpose single-lepton searches at the LHC

We test the impact of the ATLAS and CMS multilepton searches performed at the LHC with 8 as well as 13 TeV center-of-mass energy (using only the pre-2018 results) on the chargino and neutralino sector of the next-to-minimal supersymmetric Standard Model (NMSSM). Our purpose consists in analyzing the actual reach of these searches for a full model and in emphasizing effects beyond the minimal supersymmetric Standard Model (MSSM) that affect the performance of current (MSSM-inspired) electroweakino searches. To this end, we consider several scenarios characterizing specific features of the NMSSM electroweakino sector. We then perform a detailed collider study, generating Monte Carlo events through pythia and testing against current LHC constraints implemented in the public tool checkmate. We find e.g., that supersymmetric decay chains involving intermediate singlino or Higgs-singlet states can modify the naive MSSM-like picture of the constraints by inducing final states with softer or less easily identifiable SM particles—reversely, a compressed configuration with singlino next-to-lightest supersymmetric particle occasionally induces final states that are rich with photons, which could provide complementary search channels.

Florian Domingo

South Africa

Jong Soo Kim

Pablo Martín-Ramiro

Roberto Ruiz de Austri

Confronting the neutralino and chargino sector of the NMSSM with the multilepton searches at the LHC

Several ideas exist on how the stringent mass limits from LHC on new colored particles can be avoided. One idea are the so-called “stealth” scenarios in which missing transversal energy (<math><msub><mi>E</mi><mi>T</mi></msub></math>) is avoided due a peculiar mass configuration. It is usually assumed that the cascade decay of the dominantly produced colored particle finishes in a two-body decay, where this mass configuration leads to a very small amount of <math><msub><mi>E</mi><mi>T</mi></msub></math>. We discuss here the potential impact of other decay channels, either loop-induced or via off-shell mediators. It is shown that those channels already become important even for moderate branching ratios of 10%. Larger branching ratios, in particular, into a photon can completely wash out all benefits of the stealth setup. We discuss this in a model-independent form, but also at the simplest supersymmetry stealth scenario which can be realized in the next-to-minimal supersymmetric standard model.

Manuel E. Krauss

Florian Staub

Illuminating stealth scenarios at the LHC

We consider pair-production of electroweakinos promptly decaying to light gravitinos in general gauge mediation scenarios within the minimal supersymmetric standard model. Typically the presence of photons and missing transverse momentum is the key signature for this kind of scenarios. We highlight where LHC analyses which have originally been designed to probe different scenarios provide complementary constraints with respect to the dedicated searches and we present the constraints on the parameter space.