相关论文: Rare $Z$ Boson Decays to a Hidden Sector

Most models of new physics contain extended Higgs sectors with multiple Higgs bosons. The observation of an additional Higgs boson, besides the $\sim 125$ GeV `$h_{\rm obs}$', will thus serve as an irrefutable evidence of physics beyond the…

We examine the possibility of using rare, 3-body decays of a new neutral gauge boson, \ztwo, to probe its gauge couplings at hadron colliders. Specifically, we study the decays $\ztwo\to W\ell\nu$ and $\ztwo\to Z\nu\bar\nu$ and find that…

We have presented a theoretical study of exclusive rare $W$-boson decays, $W\to V\ell\bar{\nu}_\ell$ with $V$ denoting a neutral vector meson and $\ell=e$ or $\mu$, in the standard model. The leading-order contributions to these processes…

We discuss some rare Z decay signatures associated with extensions of the Standard Model with spontaneous lepton number violation at the electroweak scale. We show that single-photon Z decays such as $Z \to \gamma H$ and $Z \to \gamma J J$…

In this article, we recast and combine the CMS and ATLAS analyses of the Standard Model Higgs boson decaying to a pair of $W$ bosons in order to search for low-mass resonances in this channel. We provide limits on the corresponding cross…

The Higgs boson may have decay channels that are not predicted by the Standard Model. We discuss the prospects of probing exotic Higgs decays at the LHC using the 4-lepton final state. We study two specific scenarios, with new particles…

This Letter proposes a new signature for confining dark sectors at the Large Hadron Collider. Under the assumption of a QCD-like hidden sector, hadronic jets containing stable dark bound states could manifest in proton-proton collisions. We…

We investigate the potential reach of a search for a long-lived/prompt dark vector boson $Z_D$, also called dark $Z$, and a prompt dark Higgs boson $h_D$ through exotic decays of the observed Higgs boson $h$ into either $Z_DZ_D$, $h_Dh_D$,…

We improve the theoretical predictions for rare $Z$-boson decays, $Z\to V\ell^+\ell^-$ ($\ell=e$ or $\mu$), where $V$ denotes a heavy vector quarkonium including $J/\Psi$, $\Psi (2S)$, and $\Upsilon (nS)$ with $n=1,2,3$. These processes are…

The possibility of a scalar messenger that can couple the Standard Model (SM) to a hidden sector has been discussed in a variety of contexts in the literature in recent years. We consider the case that a new scalar singlet charged under an…

The Large Electron-Positron (LEP) collider experiments have constrained the mass of the Standard Model (SM) Higgs boson to be above 114.4 GeV. This bound applies to all extensions of the SM where the coupling of a Higgs boson to the Z boson…

We investigate a so-called 331 extension of the Standard Model gauge sector which accommodates neutrino masses and where the lightest of the new neutral fermions in the theory is a viable particle dark matter candidate. In this model,…

Searches for dark matter produced via scalar resonances in final states consisting of Standard Model (SM) particles and missing transverse momentum are of high relevance at the LHC. Motivated by dark-matter portal models, most existing…

We revisit a class of Z' explanations of the anomalies found by the LHCb collaboration in $B$ decays, and show that the scenario is tightly constrained by a combination of constraints: (i) LHC searches for di-muon resonances, (ii)…

We assess the current state of searches at the LHC for additional Higgs bosons in light of both direct limits and indirect bounds coming from coupling measurements of the Standard Model-like Higgs boson. Given current constraints, we…

This paper reports on a search for an extended scalar sector of the standard model, where a new CP-even (odd) boson decays to a Z boson and a lighter CP-odd (even) boson, and the latter further decays to a b quark pair. The Z boson is…

Topological searches for neutral scalar bosons S0 produced in association with a Z0 boson via the Bjorken process e+e- to SZ at centre-of-mass energies of 91GeV and 183-209GeV are described. These searches are based on studies of the recoil…

We evaluate the LHC's potential of observing Higgs boson decays into light elementary or composite resonances through their hadronic decay channels. We focus on the Higgs boson production processes with the largest cross sections, $pp\to h$…

This Letter presents a search for new resonances with mass larger than 250 GeV, decaying to a $Z$ boson and a photon. The dataset consists of an integrated luminosity of 3.2 fb$^{-1}$ of $pp$ collisions collected at $\sqrt{s} = 13$ TeV with…

Exotic decays of the Standard Model-like Higgs boson into beyond-the-Standard Model particles are predicted in a wide range of well-motivated theories. The enormous samples of Higgs bosons that have been and will be produced at the Large…