1,721,129 research outputs found
Heavy neutrinos, Z' and Higgs bosons at the LHC: new particles from an old symmetry
No full textA new era in particle physics is being spurred on by new data from the Large Hadron Collider. Non-vanishing neutrino masses represent firm observational evidence of new physics beyond the Standard Model. An extension of the latter, based on a SU(3)C × SU(2)L × U(1)Y × U(1)B-L symmetry, incorporating an established Baryon minus Lepton number invariance, is proposed as a viable and testable solution to the neutrino mass problem. We argue that LHC data will probe all the new content of this model: heavy neutrinos, an extra gauge boson emerging from spontaneous breaking of the additional gauge group at the TeV scale, onset by a new heavier Higgs boson, also visible at the CERN proton-proton collider. An even more exciting version of this model is the one exploiting Supersymmetry: firstly, it incorporates all its well-known benefits; secondly, it alleviates the flaws of its more minimal realisations. Finally, this model provides a credible cold Dark Matter candidate, the lightest sneutrino, detectable in both underground and collider experiment
Supersymmetry beyond minimality: from theory to experiment
No full textThe book contains five parts. Part I is core material and is necessary to develop any of the following parts, which are in turn largely independent from one another. Part I could be the material for a 1-semester course, whereas any of the latter can be taught separately in more advanced and shorter modules. The authors discuss non-minimal supersymmetry models, in a bottom-up approach that interconnects experimental phenomena in the fermionic and bosonic sectors, many of which postdate the inception of supersymmetry, such as the discovery of neutrino masses and the evidence of a Higgs boson, or which are simply not covered in previous textbooks, like CP and lepton flavour violation
Light Signatures at the LHC
Full text linkIn this work, we discuss a distinctive
() signal at the Large Hadron Collider (LHC), where the `Higgs' label
refers to the SM-like Higgs state discovered in 2012 or a lighter one in the
framework of a theoretical model embedding a spontaneously broken
symmetry in addition to the Standard Model (SM) gauge group. The additional
symmetry generates a very light state, with both vector and axial
(non-universal) couplings to fermions, which are able to explain the so-called
Atomki anomaly, compliant with current measurements of the Anomalous Magnetic
Moments (AMMs) of electron and muon as well as beam dump experiments. We show
that the cross section for this process should be sufficiently large to afford
one with significant sensitivity during Run 3 of the LHC
Alleviating the B i → D τ ν τ and B i → D a - τ ν τ puzzle in the MSSM
No full textWe show that Supersymmetric effects driven by penguin contributions to the b→cτντ transition are able to account simultaneously for a sizeable increase of both branching ratios of B̄ →Dτν̄ τ and B̄ →D∗τν̄ τ with respect to the Standard Model predictions, thereby approaching their experimentally measured values. We emphasize that a light chargino and neutralino, with masses less than 300 GeV, in addition to a large stau/sneutrino mass and a large tanβ, are essential for enhancing the effect of the lepton penguin τντW±, which is responsible for the improved theoretical predictions with respect to current data
Explanation of the 17 MeV Atomki Anomaly in a U(1)'-extended 2-Higgs doublet model
No full textMotivated by an anomaly observed in the decay of an excited state of Beryllium by the Atomki collaboration, we study an extension of the Standard Model with a gauged U(1)' symmetry in presence of a 2-Higgs Doublet Model structure of the Higgs sector. We show that this scenario complies with a variety of experimental results and is able to explain the potential presence of a resonant spin-1 gauge boson, Z', with a mass of 17 MeV in the Atomki experimental data, for appropriate choices of U(1)' charges and Yukawa interactions
Explaining electron and muon g − 2 anomalies in an Aligned 2-Higgs Doublet Model with right-handed neutrinos
No full textWe explain anomalies currently present in various data samples used for the measurement of the anomalous magnetic moment of electron (ae) and muon (au) in terms of an Aligned 2-Higgs Doublet Model with right-handed neutrinos. The explanation is driven by one and two-loop topologies wherein a very light CP-odd neutral Higgs state (A) contributes significantly to au but negligibly to ae, so as to revert the sign of the new physics corrections in the former case with respect to the latter, wherein the dominant contribution is due to a charged Higgs boson (H±) and heavy neutrinos with mass at the electroweak scale. For the region of parameter space of our new physics model which explains the aforementioned anomalies we also predict an almost background-free smoking-gun signature of it, consisting of H± A production followed by Higgs boson decays yielding multi-τ final states, which can be pursued at the Large Hadron Collider
Unveiling E<sub>6</sub>SSM Scalar Diquarks at the HL-LHC
No full textWe investigate the phenomenology of scalar diquarks with sub-TeV masses within the framework of the E6 Supersymmetric Standard Model (E6SSM) at the Large Hadron Collider (LHC). Focusing on the lightest of the six diquarks predicted by the model, we select some representative low masses for them in a parameter space region consistent with experimental constraints from direct searches for additional Higgs boson(s), Cold Dark Matter (CDM), and supersymmetry, as well as from flavor physics analyses. Using Monte Carlo (MC) simulations, we assess these benchmark points against the latest LHC results corresponding to an integrated luminosity of 140 fb−1. We further evaluate the signal significance of the pair-production of these diquarks, when each of them decays into tb pairs, at the s√=13 TeV LHC Run 3 with design integrated luminosity of 300 fb−1, and also at the 3000 fb−1 High-Luminosity LHC (HL-LHC). Our analysis yields a statistical significance exceeding 3σ at the HL-LHC for diquark masses up to 1 TeV, indicating promising prospects for their discovery
Di-photon decay of a light Higgs state in the BLSSM
No full textIn the context of the B −L Supersymmetric Standard Model (BLSSM), we investigate the consistency of a light Higgs boson, with mass around 90 − 95 GeV, with the results of a search performed by the CMS collaboration in the di-photon channel at the integrated luminosity of 35.9 fb−1 and √s = 13 TeV
New physics suggested by Atomki anomaly
No full textWe consider several extensions of the Standard Model (SM) which can explain the anomalies observed by the Atomki collaboration in the decay of excited states of Beryllium via a new boson with a mass around 17 MeV yielding e+e- pairs. We show how both spin-0 and 1 solutions are possible and describe the Beyond the SM (BSM) scenarios that can accommodate these. They include BSM frameworks with either an enlarged Higgs, or gauge sector, or both.</p
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