Motivated by models proposed to explain the Standard Model anomalies, and the unprecedented $τ^{+}τ^{-}$ data to be collected by the Belle~II experiment during the next years, we study the kinematics of tau pair decays and propose a new method to search for lepton flavor violating processes in tau lepton decays to invisible beyond Standard Model particles, such as $τ\to \ell α$, where $\ell$ is either an electron or a muon, and $α$ is a massive particle that escapes undetected. The new method improves by one order of magnitude the expected upper limit on the $τ\to \ell α$ production in 3x1 prong tau decays and establishes the possibility of performing this search in 1x1 prong tau decays which has not been previously considered.
The decay of neutrino mass eigenstates leads to a change of the conversion and survival probability of neutrino flavor eigenstates. Remarkably, we find that the neutrino decay provides an enhancement of the expected tau appearance signal with respect to the standard oscillation scenario for the long-baseline OPERA experiment. The increase of the $ν_μ\rightarrow ν_τ$ conversion probability by the decay of one of the mass eigenstates is due to a reduction of the "destructive interference" among the different massive neutrino components. Motivated by the recently released results of the OPERA Col…
Searches for invisible Higgs decays in weak boson fusion are a well-known laboratory for jets and QCD studies. We present a series of results on tagging jets and central jet activity. First, precision analyses of the central jet activity require full control of single top production in some analyses. Second, the rate dependence on the size of the tagging jets is not limited to weak boson fusion. For the first time, we show how subjet information on the tagging jets and on the additional jet activity can be used to extract the Higgs signal. The additional observables relieve some of the pressur…
Higgs boson production in association with a $Z$-boson at the LHC is analysed, both in the Standard Model and in Simplified Model extensions for Dark Matter. We focus on $H\rightarrow$invisibles searches and show that loop-induced components for both the signal and background present phenomenologically relevant contributions to the $\mathcal{BR}(H\rightarrow\textit{inv})$ limits. In addition, the constraining power of this channel to Simplified Models for Dark Matter with scalar and pseudo-scalar mediators $ϕ$ and $A$ is discussed and compared with non-collider constraints. We find that with $…
We study the possibility of utilising the constrained mass variable, $M_{2Cons}$, in reconstructing the semi-invisible events originated from a resonant production at the LHC. While this proposal is effective for any similar antler type production mechanism, here we demonstrate with potentially interesting scenario, when the Higgs boson decays into a pair of third generation $τ$ leptons. Buoyed with a relatively large Yukawa coupling, the LHC has already started exploring this pair production to investigate the properties of Higgs in the leptonic sector. Dominant signatures through hadronic de…
Two simple ways by which the standard signals of the Standard Model Higgs boson can be depleted are: its couplings to fermions and gauge bosons can be suppressed by a universal factor, and part of its branching fraction can be drained into invisible final states. A large class of theories can impose one or both of these depletion factors, even if mild, by way of additional scalar bosons that are singlets under the Standard Model but mix with the Higgs boson. We perform a comprehensive survey of the present status of the depleted Higgs boson, and discuss future prospects for detecting the prese…
We propose a novel method in that quark-gluon tagging of the jets emitted as initial state radiation (ISR) can boost searches of invisible Higgs from gluon fusion processes against irreducible electroweak vector boson productions. While quark ISR typically takes up a dominant portion than gluon in the background processes mainly by frequent quark-gluon initiated hard scatterings at the LHC, gluon ISR portion in the gluon fusion can be significantly larger in the central region of detector. Focusing on invisible Higgs searches using jet substructure variables capturing the new features, we demo…
We show that single photon searches at LEP constrain the tau neutrino magnetic moment to be less than ${\cal O}(10^{-6})~μ_B$. This bound is competitive with low energy ($s\simeq (30~GeV)^2$) single photon searches.
It is argued that, in $H \to $ invisibles searches with $Z(\ell\ell)H$ associated production at the LHC, the signal efficiency can be sensibly improved via a detailed study of the $Z$ boson polarization, discriminating between the signal and the dominant-irreducible $Z(\ell\ell)Z(νν)$ background. We first present a comprehensive polarization study, obtaining the complete set of angular coefficients $A_i$ in the Collins-Soper reference frame and identifying the dominant phenomenological effects. Then, we show the results for a realistic Monte Carlo study to $H\to$ invisibles, taking the polariz…
We study the implications of the Higgs discovery and of recent results from dark matter searches on real singlet scalar dark matter. The phenomenology of the model is defined by only two parameters, the singlet scalar mass $m_S$ and the quartic coupling $a_2$ between the SU(2) Higgs and the singlet scalar. We concentrate on the window $5 < m_S/{\rm GeV} < 300$. The most dramatic impact on the viable parameter space of the model comes from direct dark matter searches with LUX, and, for very low masses in the few GeV range, from constraints from the invisible decay width of the Higgs. In the res…
Braking protons at the EIC: from invisible meson decay to new physics searches
University of California Santa Cruz（加州大学圣克鲁兹分校）；Santa Cruz Institute for Particle Physics（圣克鲁兹粒子物理研究所）；Technion - Israel Institute of Technology（以色列理工学院）；Brookhaven National Laboratory（布鲁克海文国家实验室）；CERN（欧洲核子研究中心）；Massachusetts Institute of Technology（麻省理工学院）；Universität Zürich（苏黎世大学）
We estimate the most important corrections to the branching ratios for the invisible decays of quarkonium states, arising from possible extensions of the standard model. Among the possibilities considered are the presence of extra Z-bosons, minimal supersymmetric extensions of the standard model with R-parity violation, and decays into goldstinos. Prospects of detecting these corrections at existing and future B-factories and tau-charm factories are discussed.
Although the existence of Dark Matter (DM) has been suggested by various astrophysical observations, it has not yet been discovered today. We can assume a scenario in which the particles that account for the DM can interact with the Standard Model particles only through their couplings with the Higgs sector, the so-called Higgs-portal model. This model can be investigated by collider experiment using the invisible decay of Higgs boson. In this study, we evaluate the search ability of International Linear Collider (ILC) for invisible decay of the Higgs using International Large Detector (ILD) f…
We present next-to-leading order QCD and electroweak (EW) theory predictions for $V+2\,$jet production, with $V=Z,W^{\pm}$, considering both the QCD and EW production modes and their interference. We focus on phase-space regions where $V+2\,$jet production is dominated by vector-boson fusion, and where these processes yield the dominant irreducible backgrounds in searches for invisible Higgs boson decays. Predictions at parton level are provided together with detailed prescriptions for their implementation in experimental analyses based on the reweighting of Monte Carlo samples. The key idea i…
Supersymmetry is perhaps most effectively probed at the Tevatron through production and decay of weak gauginos. Most of the analyses of weak gaugino observables require electrons or muons in the final state. However, it is possible that the gauginos will decay primarily to tau leptons, thus complicating the search for supersymmetry. The motivating reasons for high tau multiplicity final states are discussed in three approaches to supersymmetry model building: minimal supergravity, gauge mediated supersymmetry breaking, and more minimal supersymmetry. The concept of ``e/mu/tau candidate'' is in…
The Compact Linear Collider (CLIC) is a proposed TeV-scale high-luminosity electron-positron collider at CERN. The first CLIC running stage, at 380\,GeV, will focus on precision Higgs boson and top quark studies while the main aim of the subsequent high-energy stages, at 1.5 TeV and 3 TeV, is to extend the sensitivity of CLIC to different Beyond the Standard Model (BSM) scenarios. We studied the prospects for measuring invisible Higgs boson and additional heavy scalar decays using CLIC data at 380 GeV and 1.5 TeV. The analysis is based on the WHIZARD event generator, with fast simulation of th…
We build a class of invisible axion models with tree-level Flavor Changing Neutral Currents completely controlled by the fermion mixing matrices. The scalar sector of these models contains three-Higgs doublets and a complex scalar gauge singlet, with the same fermionic content than the Standard Model. A horizontal Peccei-Quinn symmetry provides a solution to the strong CP problem and predicts the existence of a very light and weakly coupled pseudo-Goldstone boson, the invisible axion or familon. A phenomenological analysis is performed taking into account familon searches in rare kaon and muon…
Given its weak coupling to bottom quarks and tau leptons, the Higgs boson may predominantly decay into invisible particles like gravitinos, neutralinos, or gravitons. We consider the manifestation of such an invisibly decaying Higgs boson in weak boson fusion at the CERN LHC. Distinctive kinematic distributions of the two quark jets of the signal as compared to Zjj and Wjj backgrounds allow to restrict the Higgs branching ratio to 'invisible' final states to some 13% with 10fb^{-1} of data, provided events with two energetic forward jets of high dijet invariant mass and with substantial missin…
In bilinear R-Parity violating models where a term ε_3L_3H_2 is introduced in the superpotential, the tau lepton can mix with charginos. We show that this mixing is fully compatible with LEP1 precision measurements of the Zττand Wτν_τcouplings even for large values of ε_3 and of the induced vacuum expectation value v_3 of the tau-sneutrino. The single production of charginos at e+e- colliders is possible in this case and we present numerical values of the cross-section at LEP1, LEP2 and an NLC. We find maximum values of 10 pb at LEP1 and 1 fb at NLC, while the corresponding values at LEP2 are …
In this paper we show that the excess of the tau tau events with respect to the Standard Model background predictions, observed by the ATLAS and CMS collaborations and interpreted as the evidence of the Higgs-boson decay into a pair of tau-leptons, may be accounted for by properly taking into account QED radiative corrections in the modelling of the Z/gamma* -> tau tau background.
We investigate the dipole moments of the tau- neutrino at high-energy and high luminosity at linear electron positron colliders, such as CLIC or ILC through the analysis of the reaction $e^{+}\, e^{-}\rightarrow ν\, \bar ν\,γ$ in the framework of the $SU(4)_L \times U(1)_X$ model. The limits on dipole moment were obtained for integrated luminosity of $\cal{L}$= 500-2000\, fb$^{-1}$ and center of mass between 0.5 and 3.0 TeV. The estimated limits for the tau-neutrino magnetic and electric dipole moments are improved by 2-3 orders of magnitude and complement previous studies on the dipole moment…
Searches for lepton flavor violation in tau decays are unambiguous signatures of new physics. The branching ratios of tau leptons at the level of 10^-10 - 10^-9 can be probed with 50 ab^-1 of electron-positron annihilation data being collected by the Belle II experiment at the world's highest luminosity accelerator, the SuperKEKB, located at the High Energy Accelerator Research Organization, KEK, in Tsukuba, Japan. Searches with such expected sensitivity will either discover new physics or strongly constrain several new physics models.
The mass of the Standard Model (SM) Higgs boson was constrained by the Large Electron-Positron (LEP) collider to be above 114.4 GeV. Simple extensions of the scalar sector like adding singlets and/or doublets allow the lightest Higgs to be much lighter via a reduction in its coupling to gauge bosons. Such a light Higgs could have evaded the LEP searches but could be detected at the Large Hadron Collider (LHC) in the process pp -> h j -> tau^+ tau^- j, where j is a resolved jet. We conclude that in some Beyond the Standard Model (BSM) extensions of the scalar sector, a very light Higgs state co…
We study the invisible Majorana fermions of $χ$ in bottomed baryon decays with flavor-changing neutral currents (FCNCs) based on the model-independent effective Lagrangian between the quarks and invisible particles. From the bounds of the coupling constants extracted from the experiments, we examine the decay branching ratios of $Λ_b\toΛχχ$, $Ξ_b^{0(-)}\toΞ^{0(-)}χχ$, $Λ_b\to n χχ$, $Ξ_b^{-}\to Σ^{-} χχ$, $Ξ_b^{0}\to Σ^{0} χχ$, and $Ξ_b^{0}\to Λχχ$, which can be as large as $6.3,~9.2,~5.7,~5.8,~2.7$, and $1.0\times10^{-5}$ for $m_χ=2$ GeV, respectively. Some of these decays are accessible to t…
The galactic center excess of gamma ray photons can be naturally explained by light Majorana fermions in combination with a pseudoscalar mediator. The NMSSM provides exactly these ingredients. We show that for neutralinos with a significant singlino component the galactic center excess can be linked to invisible decays of the Standard-Model-like Higgs at the LHC. We find predictions for invisible Higgs branching ratios in excess of 50 percent, easily accessible at the LHC. Constraining the NMSSM through GUT-scale boundary conditions only slightly affects this expectation. Our results complemen…
We study the decay of 125 GeV Higgs boson to light LSP neutralino in the phenomenological minimal supersymmetric standard model in the context of collider searches and astrophysical experiments. We consider the parameter space for light neutralinos that can be probed via the invisible Higgs decays and higgsino searches at the ILC. We consider the cases where the light neutralino is compatible with the observed relic density or where the thermal relic is over-abundant, pointing to non-standard cosmology. In the former case, when the neutralino properties give rise to under-abundant relic densit…
The tau lepton can be more composite than naively expected in models of strong electroweak symmetry breaking with tri-bimaximal lepton mixing. New leptonic resonances required by custodial symmetry, the tau custodians, can then be the first signal of this lepton flavor realization. Tau custodians can be very light, decaying almost exclusively into taus. The LHC reach for these new leptons is up to masses of 240, 480 and 720 GeV for sqrt{s}=14 TeV and an integrated luminosity of 30, 300 and 3000 fb^{-1}, respectively. Our analysis can be extended to any pair produced particles decaying mostly i…
It has been recently suggested in hep-ph/9911535 and hep-ph/0006324 that the fourth generation of leptons and quarks is not excluded by the precision Z-boson measurements, provided that the mass of the fourth neutrino is around 50 GeV and that its mixing with the neutrinos of the first three generations is negligibly small. We would like to note that in this case the decay rate of the Standard Model Higgs boson into the pair of such neutrinos would be about two orders of magnitude higher than than the Higgs to b-bbar rate. Thus, the predominant decay mode of the Higgs would be invisible, which…
A method to search for particles of unknown masses in final states with two invisible particles is presented. Searching for final states with missing energy is a challenging task usually performed in the tail of a missing energy related distribution. The search method proposed is based on a 2-Dimensional mass reconstruction of the final state with two invisible particles. Thus, a bump hunting is possible, allowing a stronger signal versus background discrimination. Parameters of the BSM theory can be extracted from the mass distributions, a valuable step towards understanding its true nature. …
Using a data sample of $58\times 10^6$ $J/ψ$ decays collected with the BES II detector at the BEPC, searches for invisible decays of $η$ and $η^\prime$ in $J/ψ$ to $ϕη$ and $ϕη^\prime$ are performed. The $ϕ$ signals, which are reconstructed in $K^+K^-$ final states, are used to tag the $η$ and $η^\prime$ decays. No signals are found for the invisible decays of either $η$ or $η^\prime$, and upper limits at the 90% confidence level are determined to be $1.65 \times 10^{-3}$ for the ratio $\frac{B(η\to \text{invisible})}{B(η\toγγ)}$ and $6.69\times 10^{-2}$ for $\frac{B(η^\prime\to \text{invisibl…
The $τ$ polarization can be easily measured at LHC in the 1-prong hadronic $τ$ decay channel by measuring what fraction of the $τ$-jet momentum is carried by the charged track. A simple cut requiring this fraction to be >0.8 retains most of the polarization of $τ=$+1 $τ$-jet signal while suppressing the polarization of $τ=$-1 $τ$-jet background and practically eliminating the fake $τ$ background. This can be utilized to extract the charged Higgs signal. It can be also utilized to extract the SUSY signal in the stau NLSP region, and in particular the stau co-annihilaton region.
We confront the indications of lepton flavor universality (LFU) violation observed in semi-tauonic $B$ meson decays with new physics (NP) searches using high $p_T$ tau leptons at the LHC. Using effective field theory arguments we correlate possible non-standard contributions to semi-tauonic charged currents with the $τ^+ τ^-$ signature at high energy hadron colliders. Several representative standard model extensions put forward to explain the anomaly are examined in detail: (i) weak triplet of color-neutral vector resonances, (ii) second Higgs doublet and (iii) scalar or (iv) vector leptoquark…
In the Standard Model there are several canonical examples of pure leptonic processes involving the muon, the electron and the corresponding neutrinos which are connected by the crossing symmetry: i) the decay of muon, ii) the inverse muon decay, and iii) the annihilation of a muon and an electron into two neutrinos. Although the first two reactions have been observed and measured since long ago, the third process, resulting in the invisible final state, has never been experimentally tested. It may go either directly, or, at low energies, via the annihilation of a muon and an electron from an …
The ATLAS and CMS collaborations recently reported a mild excess in the diphoton final state pointing to a resonance with a mass of around 750 GeV and a potentially large width. We consider the possibility of a scalar resonance being produced via gluon fusion and decaying to electroweak gauge bosons, jets and pairs of invisible particles, stable at collider scales. We compute limits from monojet searches on such a resonance and test their compatibility with the requirement for a large width. We also study whether the stable particle can be a a dark matter candidate and investigate the correspo…
It is now a firmly established fact that all family lepton numbers are violated in Nature. In this paper we discuss the implications of this observation for future searches for rare tau decays in the supersymmetric see-saw model. Using the two loop renormalization group evolution of the soft terms and the Yukawa couplings we show that there exists a lower bound on the rate of the rare process mu --> e gamma of the form BR(mu --> e gamma) > C BR(tau --> mu gamma) BR(tau --> e gamma), where C is a constant that depends on supersymmetric parameters. Our only assumption is the absence of cancellat…
We study the possibilities offered by muon storage rings for tau-neutrino appearance experiments due to nu_mu to nu_tau and nu_e to nu_tau oscillations. Tau event rates for such experiments are first discussed with a view to examining their variation prior to the inclusion of experimental cuts, in order to better understand how baselines, beam energies, forward peaking of decay neutrinos with increasing energies and average fluxes intercepted by detectors of various sizes can affect their optimization. Subsequently, event rates implementing cuts are computed for hadronic and wrong-sign lepton …
We study the implication of $J/ψ$ decay into invisible particles for light sterile neutrino and sub-GeV dark matter (DM). The low-energy effective field theories (EFTs) are used for the description of general neutrino interactions and the Dirac fermion DM coupled to charm quark. For $J/ψ\to γ+{\rm invisible}$, we perform the likelihood fits for the individual neutrino and DM operators with distinct Lorentz structures and photon spectra. The limits on the decay branching fractions are obtained for different neutrino or DM scenarios and then converted to the lower bounds on the new energy scales…
Universidad de La Serena（拉塞雷纳大学）；Millennium Institute for Subatomic Physics at the High Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所 (SAPHIR)）；Instituto de Física Corpuscular – CSIC - Universitat de València（瓦伦西亚大学-西班牙国家研究委员会粒子物理研究所）
We re-analyze the results of the searches for Heavy Neutral Leptons (HNLs) by the CHARM experiment. We study HNL decay channel $N\to e^{+}e^{-}ν/μ^{+}μ^{-}ν$ and show that, in addition to the constraints on the HNL's mixings with $ν_e$ or $ν_μ$, the same data also implies limits on the HNLs that mix only with $ν_τ$ and have masses in the range $380 \text{ MeV}<m_{N}\lesssim 1.6\text{ GeV}$ - the region in the parameter space that was considered in the literature as a target for HNLs searches.
We analyze the extent to which the LHC and Tevatron results as of the end of 2012 constrain invisible (or undetected) decays of the Higgs boson-like state at ~ 125 GeV. To this end we perform global fits for several cases: 1) a Higgs boson with Standard Model (SM) couplings but additional invisible decay modes; 2) SM couplings to fermions and vector bosons, but allowing for additional new particles modifying the effective Higgs couplings to gluons and photons; 3) no new particles in the loops but tree-level Higgs couplings to the up-quarks, down-quarks and vector bosons, relative to the SM, tr…
Dark photons in the MeV to GeV mass range are important targets for experimental searches. We consider the case where dark photons $A'$ decay invisibly to hidden dark matter $X$ through $A' \to XX$. For generic masses, proposed accelerator searches are projected to probe the thermal target region of parameter space, where the $X$ particles annihilate through $XX \to A' \to \text{SM}$ in the early universe and freeze out with the correct relic density. However, if $m_{A'} \approx 2m_X$, dark matter annihilation is resonantly enhanced, shifting the thermal target region to weaker couplings. For …
Weakly-coupled TeV-scale particles may mediate the interactions between normal matter and dark matter. If so, the LHC would produce dark matter through these mediators, leading to the familiar "mono-X" search signatures, but the mediators would also produce signals without missing momentum via the same vertices involved in their production. This document from the LHC Dark Matter Working Group suggests how to compare searches for these two types of signals in case of vector and axial-vector mediators, based on a workshop that took place on September 19/20, 2016 and subsequent discussions. These…
The first limit on the branching ratio of the electric charge-nonconserving invisible muon decay $Br(μ^+ \to invisible) < 5.2 \times 10^{-3}$ is obtained from the recently reported results on new determination of the Fermi constant from muon decays. The results of a feasibility study of a new proposed experiment for a sensitive search for this decay mode at the level of a few parts in 10^{11} are presented. Constrains on the $τ\to invisible$ decay rate are discussed. These leptonic charge-nonconserving processes may hold in four-dimensional world in models with infinite extra dimensions, thus …
Neutrino mass generation through the Higgs mechanism not only suggests the need to reconsider the physics of electroweak symmetry breaking from a new perspective, but also provides a new theoretically consistent and experimentally viable paradigm. We illustrate this by describing the main features of the electroweak symmetry breaking sector of the simplest type-II seesaw model with spontaneous breaking of lepton number. After reviewing the relevant "theoretical" and astrophysical restrictions on the Higgs sector, we perform an analysis of the sensitivities of Higgs boson searches at the ongoin…
Searches for supersymmetry (SUSY) often rely on a combination of hard physics objects (jets, leptons) along with large missing transverse energy to separate New Physics from Standard Model hard processes. We consider a class of ``double-invisible'' SUSY scenarios: where squarks, stops and sbottoms have a three-body decay into two (rather than one) invisible final-state particles. This occurs naturally when the LSP carries an additional conserved quantum number under which other superpartners are not charged. In these topologies, the available energy is diluted into invisible particles, reducin…
We study the implications of the searches based on H -> tau^+ tau^- by the ATLAS and CMS collaborations on the parameter space of the two Higgs doublet model (2HDM). In the 2HDM, the scalars can decay into a tau pair with a branching ratio larger than the SM one, leading to constraints on the 2HDM parameter space. We have also discussed the implications for the 2HDM of the recent di-muon search by the ATLAS collaboration for a CP-odd scalar in the mass range 4-12 GeV.
Proton decay, and the decay of nucleons in general, constitutes one of the most sensitive probes of high-scale physics beyond the Standard Model. Most of the existing nucleon decay searches have focused primarily on two-body decay channels, motivated by Grand Unified Theories and supersymmetry. However, many higher-dimensional operators violating baryon number by one unit, $ΔB = 1$, induce multi-body nucleon decay channels, which have been only weakly constrained thus far. While direct searches for all such possible channels are desirable, they are highly impractical. In light of this, we argu…
New particles $ϕ$ in the MeV-GeV range produced at colliders and escaping detection can be searched for at operating $b-$ and $τ-$factories such as Belle II. A typical search topology involves pair-produced $τ$s (or mesons), one of which decaying to visibles plus the $ϕ$, and the other providing a tag. One crucial impediment of these searches is the limited ability to reconstruct the parents' separate boosts. This is the case in the 'typical' topology where both decay branches include escaping particles. We observe that such topology lends itself to the use of kinematic variables such as $M_2$…
The leptonic decays of the tau lepton provide relevant tests on the structure of the weak currents and the universality of their couplings to the gauge bosons. The hadronic tau decay modes constitute an ideal tool for studying low--energy effects of the strong interaction in very clean conditions. Accurate determinations of the QCD coupling and the strange quark mass have been obtained with tau decay data. New physics phenomena, such as a non-zero tau neutrino mass or violations of conservation laws can also be searched for with tau decays.
We calculate the one-loop induced couplings of two gaugino-like neutralinos to the $Z$ and Higgs bosons in the Minimal Supersymmetric Standard Model. These couplings, which vanish at the tree level, can be generated through loops involving fermions and sfermions. We show that, while the neutralino contribution to the invisible $Z$ boson decay width remains small, the loop induced couplings to the lightest Higgs boson might be sufficiently large to yield a rate of invisible decays of this Higgs boson that should be detectable at future $e^+e^-$ colliders. We also study the implications of these…
We analyze a displaced dilepton signal expected at the LHC for a tau left sneutrino as the lightest supersymmetric particle with a mass in the range $45$-$100$ GeV. The sneutrinos are pair produced via a virtual $W$, $Z$ or $γ$ in the $s$ channel and, given the large value of the tau Yukawa coupling, their decays into two dileptons or a dilepton plus missing transverse energy from neutrinos can be significant. The discussion is carried out in the $μν$SSM, where the presence of $R$-parity violating couplings involving right-handed neutrinos solves the $μ$ problem and can reproduce the neutrino …
We investigate the scenario where the dark matter only interacts with the charged leptons in the standard model via a neutral vector mediator $Z'$. Such a scenario with a 430 GeV dark matter can fit the recent positron fluxes observed by the AMS-02 Collaborations, with the reasonable boost factors. We study the possibility of searching such leptophilic $Z'$ via its lepton final states and invisible decay modes at the future electron-positron colliders, such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). We find that for the benchmark models with $Z'$ mass fr…
We consider the process in which a Higgs particle is produced in association with jets and show that monojet searches at the LHC already provide interesting constraints on the invisible decays of a 125 GeV Higgs boson. Using the existing monojet searches performed by CMS and ATLAS, we show the 95% confidence level limit on the invisible Higgs decay rate is of the order of the total Higgs production rate in the Standard Model. This limit could be significantly improved when more data at higher center of mass energies are collected, provided systematic errors on the Standard Model contribution t…
