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Unveiling hidden physics at the LHC
Abstract The field of particle physics is at the crossroads. The discovery of a Higgs-like boson completed the Standard Model (SM), but the lacking observation of convincing resonances Beyond the SM (BSM) offers no guidance for the future of particle physics. On the other hand, the motivation for New Physics has not diminished and is, in fact, reinforced by several striking anomalous results in many experiments. Here we summarise the status of the most significant anomalies, including the most recent results for the flavour anomalies, the multi-lepton anomalies at the LHC, the Higgs-like excess at around 96 GeV, and anomalies in neutrino physics, astrophysics, cosmology, and cosmic rays. While the LHC promises up to 4 $$\hbox {ab}^{-1}$$ ab - 1 of integrated luminosity and far-reaching physics programmes to unveil BSM physics, we consider the possibility that the latter could be tested with present data, but that systemic shortcomings of the experiments and their search strategies may preclude their discovery for several reasons, including: final states consisting in soft particles only, associated production processes, QCD-like final states, close-by SM resonances, and SUSY scenarios where no missing energy is produced. New search strategies could help to unveil the hidden BSM signatures, devised more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10353722
Journal Name:
The European Physical Journal C
Volume:
82
Issue:
8
ISSN:
1434-6052
1. Abstract A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a $${\mathrm{Z}}$$ Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137 $$\,\text {fb}^{-1}$$ fb - 1 , at a center-of-mass energy $$\sqrt{s} = 13\,\text {TeV}$$ s = 13 TeV . No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported.
The possibility in supersymmetric scenarios that the dark matter candidate is a Higgsino-like neutralino means that its production can be associated with Higgs bosons. Taking advantage of this fact, we propose a LHC search strategy for gluinos with$$\tau$$$\tau$leptons in the final state, coming from the decay of a Higgs boson. We consider the strong production of a pair of gluinos, one of which decays into the Higgsino plus jets while the other decays into the bino plus jets. In turn, this bino decays into the Higgsino plus a Higgs boson which finally decays into a$$\tau$$$\tau$-lepton pair. Therefore, the experimental signature under study consists of 4 jets, 2$$\tau$$$\tau$leptons, and a large amount of missing transverse energy. This work represents a proof of principle of a search that is sensitive to a spectrum such that the gluino does not directly decay to the dark matter candidate but to an intermediate electroweakino that then produces Higgs bosons in its subsequent decay. Our cut-based search strategy allows us to reach, for a LHC center-of-mass energy of 14 TeV and a total integrated luminosity of 1 ab$$^{-1}$$${}^{-1}$, significances of up to 2 standard deviations, considering systematic uncertainties in the SM backgroundmore »