In this paper, we study the light scalar and pseudoscalar invisible particles in the flavor changing neutral current processes of the $B_c$ meson. Effective operators are introduced to describe the couplings between quarks and light invisible particles. The Wilson coefficients are extracted from the experimental results of the $B$ and $D$ mesons, which are used to predict the upper limits of the branching fractions of the similar decay processes for the $B_c$ meson. The hadronic transition matrix element is calculated with the instantaneously approximated Bethe-Salpeter method. The upper limits of the branching fractions when $m_χ$ taking different values are presented. It is found that at some region of $m_χ$, the channel $B_c\to D_s^{(\ast)}χχ$ has the largest upper limit which is of the order of $10^{-6}$, and for $B_c\to D_s^\astχχ^\dagger$, the largest value of the upper limits can achieve the order of $10^{-5}$. Other decay modes, such as $B_c\to D^{(*)}χχ^{(\dagger)}$ and $B_c\to B^{(*)}χχ^{(\dagger)}$, are also considered.
In models of Randall-Sundrum type orthopositronium (o-Ps) can disappear due to tunnelling into additional dimension(s). The experimental signature of this effect is the invisible decay of orthopositronium. We point out that this process may occur at a rate within two or three orders of magnitude of the present experimental upper limit. We discuss this in details and stress that the existence of invisible decay of orthopositronium in vacuum could explain the o-Ps decay rate puzzle. Thus, our result enhances the existing motivation and justifies efforts for a more sensitive search for o-Ps->invi…
To know the total width of the recently discovered Higgs boson particle, it is important to measure the invisible decay width of the Higgs boson. However, the signal for this measurement at the LHC, i.e., a charged lepton pair and missing energy in the final state, cannot be definitely understood as the product of the intermediate produced $Z$ and $H$ bosons due to the possible interaction between dark matter and a $Z$ boson or quarks, which can be described by representative effective operators. First, we consider the relic abundance, the LUX direct detection experiment and the result of sear…
In this talk, we will review Inert Triplet Model (ITM) which provide candidate for dark matter (DM) particles. Then we study possible decays of Higgs boson to DM candidate and apply current experimental data for invisible Higgs decay to constrain parameter space of ITM. We also consider indirect search for DM and use FermiLAT data to put constraints on parameter space. Ultimately we compare this limit with constraints provided by LUX experiment for low mass DM and invisible Higgs decay.
In this work we consider the standard model extended with singlet sterile neutrinos with mass in the eV range and mixed with the active neutrinos. The active-sterile neutrino mixing renders new contributions to the invisible Z decay width which, in the case of light sterile neutrinos, depends on the active-sterile mixing matrix elements only. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models.
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.
We recompute the invisible Higgs decay width arising from Higgs-graviscalar mixing in the ADD model, comparing the original derivation in the non-diagonal mass basis to that in a diagonal mass basis. The results obtained are identical (and differ by a factor of 2 from the original calculation) but the diagonal-basis derivation is pedagogically useful for clarifying the physics of the invisible width from mixing. We emphasize that both derivations make it clear that a direct scan in energy for a process such as $WW\to WW$ mediated by Higgs plus graviscalar intermediate resonances would follow a…
In this paper, we study the FCNC decay processes of $B$ and $B_c$ meson, in which one invisible particle is emitted. Both the spin-0 and spin-1 cases are considered. The model-independent effective Lagrangian is introduced to describe the coupling between the light invisible boson and quarks. The constraints of the coupling coefficients are extracted by experimental upper limits of the missing energy in $B$ meson decays. The bounds are used to predict the upper limits of branching fractions of corresponding $B_c$ decays, which are of the order of $10^{-6}$ or $10^{-5}$ when final meson is pseu…
Bounds on invisible decays of the Higgs boson from $t\bar{t}H$ production were inferred from a CMS search for stop quarks decaying to $t\bar{t}$ and missing transverse momentum. Limits on the production of $t\bar{t}H$ relied on the efficiency of the CMS selection for $t\bar{t}H$, as measured in a simulated sample. An error in the generation of the simulated sample lead to a significant overestimate of the selection efficiency. Corrected results are presented.
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…
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 point out that some models with infinite additional dimension(s) of Randall-Sundrum type predict the disappearance of orthopositronium (o-Ps) into additional dimension(s). The experimental signature of this effect is the o-Ps -> invisible decay of orthopositronium which may occur at a rate within three orders of magnitude of the present experimental upper limit. This result enhances existing motivations for a more sensitive search for this decay mode and suggests additional directions for testing extra dimensions in non accelerator experiments.
One of the main neutrino oscillation parameters whose value has not been determined very precisely is the leptonic $δ_{CP}$ phase. Since neutrinos have a tiny but finite mass they can undergo decay both visibly and invisibly. The effect of invisible decay of the third mass eigen state $ν_3$ on the sensitivity to $δ_{CP}$ is analysed here using atmospheric neutrino and anti-neutrino events. Effects of detector resolutions and systematic uncertainties are studied to identify the optimum resolutions and efficiencies required by a detector to obtain a significant sensitivity even in presence of de…
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…
The theoretical calculation of pseudo-scalar leptonic decay widths into an invisible ALP, $M \to \ell\, ν_\ell\, a$, is reviewed. Assuming generic flavour-conserving ALP couplings to SM fermions and a generic ALP mass, $m_a$, the latest experimental results for pseudo-scalar leptonic decays are used to provide updated bounds on the ALP-fermion Lagrangian sector. Constrains on the ALP-quark couplings obtained from these channels are not yet competitive with the ones derived from FCNC processes, like $M\to P\,a$ decays. These leptonic decays can, however, provide the most stringent model-indepen…
In the Standard Model (SM) of particle physics, the branching ratio for Higgs boson decays to a final state which is invisible to collider detectors, $H \rightarrow ZZ^{\star} \rightarrow ν\barν ν\barν$, is order 0.10%. In theories beyond the SM (BSM), this branching ratio can be enhanced by decays to undiscovered particles like dark matter (DM). At the Large Hadron Collider (LHC), the current best upper limit on the branching ratio of invisible Higgs boson decays is 11% at 95% confidence level. We investigate the expected sensitivity to invisible Higgs decays with the Silicon Detector (SiD) a…
The discovery of the Higgs boson suggests that also neutrinos get their mass from spontaneous symmetry breaking. In the simplest ungauged lepton number scheme, the Standard Model (SM) Higgs has now two other partners: a massive CP-even, as well as the massless Nambu-Goldstone boson, called majoron. For weak-scale breaking of lepton number the invisible decays of the CP- even Higgs bosons to the majoron lead to potentially copious sources of events with large missing energy. Using LHC results we study how the constraints on invisible decays of the Higgs boson restrict the relevant parameters, s…
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…
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…
Assuming flat universal extra dimensions, we demonstrate that for a light Higgs boson the process $pp\to W^*W^* +X \to Higgs,graviscalars +X \to invisible+X$ will be observable at the $5 σ$ level at the LHC for the portion of the Higgs-graviscalar mixing ($ξ$) and effective Planck mass ($M_D$) parameter space where channels relying on visible Higgs decays fail to achieve a $5 σ$ signal. Further, we show that even for very modest values of $ξ$ the invisible decay signal probes to higher $M_D$ than does the ($ξ$-independent) jets/$\gam$ + missing energy signal from graviton radiation. We also di…
The Higgs invisible decay width may soon become a powerful tool to probe extensions of the Standard Model with dark matter candidates at the Large Hadron Collider. In this work, we calculate the next-to-leading order (NLO) electroweak corrections to the 125 GeV Higgs decay width into two dark matter particles. The model is the next-to-minimal 2-Higgs-doublet model (N2HDM) in the dark doublet phase, that is, only one doublet and the singlet acquire vacuum expectation values. We show that the present measurement of the Higgs invisible branching ratio, BR$(H \to$ invisible $< 0.11$), does not lea…
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 pro…
The invisible signals of right-handed sneutrino decays originating from a Z' are analysed at the Large Hadron Collider. The possibility of accessing these events helps disentangling the B-L extension of Minimal Supersymmetric Standard Model from more popular scenarios of Supersymmetry. We assess the scope of the CERN machine in establishing the aforementioned signatures when accompanied by mono-jet, single-photon or Z-radiation probes through sophisticated signal-to-background simulations carried out in presence of parton shower, hadronisation as well as detector effects. We find substantial s…
We consider the decay of a generic resonance to two visible particles and any number of invisible particles. We show that the shape of the invariant mass distribution of the two visible particles is sensitive to both the mass spectrum of the new particles, as well as the decay topology. We provide the analytical formulas describing the invariant mass shapes for the nine simplest topologies (with up to two invisible particles in the final state). Any such distribution can be simply categorized by its endpoint, peak location and curvature, which are typically sufficient to discriminate among the…
In the large extra dimension model of Arkani-Hamed, Dimopoulos and Dvali the presence of an interaction between the Ricci scalar curvature and the Higgs doublet of the Standard Model makes a light Higgs boson observable at LHC at the 5 sigma level through the fusion process pp-> W*W* +X -> Higgs, graviscalars +X -> invisible+X for the portion of the Higgs-graviscalar mixing (xi) and effective Planck mass (M_D) parameter space where channels relying on visible Higgs decays fail to achieve a 5 sigma signal. However even if the LHC has a good chance of seeing a signal, it will not be able to dete…
The Higgs boson may decay mainly to an invisible mode characterized by missing energy, instead of the Standard Model channels. This is a generic feature of many models where neutrino masses arise from the spontaneous breaking of ungauged lepton number at relatively low scales, such as spontaneously broken R-parity models. Taking these models as framework, we reanalyze this striking suggestion in view of the recent data on neutrino oscillations that indicate non-zero neutrino masses. We show that, despite the smallness of neutrino masses, the Higgs boson can decay mainly to the invisible Goldst…
We consider supersymmetric models in which the lightest Higgs scalar can decay invisibly consistent with the constraints on the $126$~GeV state discovered at the CERN LHC. We consider the invisible decay in the minimal supersymmetric standard model~(MSSM), as well its extension containing an additional chiral singlet superfield, the so-called next-to-minimal or nonminimal supersymmetric standard model~(NMSSM).We consider the case of MSSM with both universal as well as nonuniversal gaugino masses at the grand unified scale, and find that only an $E_6$ grand unified model with unnaturally large …
We consider the possibility that the heavier CP-even Higgs boson~($H^0$) in the minimal supersymmetric standard model (MSSM) decays invisibly into neutralinos in the light of the recent discovery of the 126 GeV resonance at the CERN Large Hadron Collider (LHC). For this purpose we consider the minimal supersymmetric standard model with universal, non-universal and arbitrary boundary conditions on the supersymmetry breaking gaugino mass parameters at the grand unified scale. Typically, scenarios with universal and nonuniversal gaugino masses do not allow invisible decays of the lightest Higgs b…
The measurement of the invisible Z-boson decay width at e+e- colliders can be done "indirectly", by subtracting the Z-boson visible partial widths from the Z-boson total width, or "directly", from the process e+e- -> γν\barν. Both procedures are sensitive to different types of new physics and provide information about the couplings of the neutrinos to the Z-boson. At present, measurements at LEP and CHARM II are capable of constraining the left-handed Zνν-coupling, 0.45 <~ g_L <~ 0.5, while the right-handed one is only mildly bounded, |g_R| <= 0.2. We show that measurements at a future e+e- li…
We explore the possibility that $Z'$ couplings can be probed using decay modes which involve neutrinos once Standard Model backgrounds are directly determined by the data itself. For some models, sufficient statistics are available at either the SSC or LHC to render these modes useful for coupling determinations, provided the mass of the $Z'$ is not much larger than 1 TeV, if we assume other new physics background sources are absent.
We study the invisible decay of the Higgs boson into a pair of stable, heavy photons, H -> A_H A_H, in the littlest Higgs model with T-parity. For a symmetry breaking scale of f = 450 GeV, the branching ratio H -> A_H A_H can be as high as 93% for Higgs masses below 150 GeV. For f = 500 GeV, the invisible branching ratio is about 75% in the Higgs mass range 135 - 150 GeV and 10 (5.5)% for m_H = 200 (600) GeV. It drops to a few percent for f larger than 600 GeV. We have found regions in parameter space, allowed by the electroweak precision data, with such low values of f for 115 GeV < m_H < 650…
The discovery of a 126 GeV Higgs like scalar at the LHC along with the non observation of the supersymmetric particles, has in turn lead to constraining various supersymmetric models through the Higgs data. We here consider the case of both MSSM, as well its extension containing an additional chiral singlet superfield, NMSSM. We concentrate on the case where we identify the second lightest Higgs boson as the 126 GeV state discovered at the CERN LHC and consider the invisible decays of the low mass Higgs bosons in both MSSM and NMSSM. We find that in case of the MSSM with universal boundary con…
We consider the application of endpoint techniques to the problem of mass determination for new particles produced at a hadron collider, where these particles decay to an invisible particle of unknown mass and one or more visible particles of known mass. We also consider decays of these types for pair-produced particles and in each case consider situations both with and without initial state radiation. We prove that, in most (but not all) cases, the endpoint of an appropriate transverse mass observable, considered as a function of the unknown mass of the invisible particle, has a kink at the t…
In light of current atmospheric neutrino oscillation data, we revisit the invisible decay of the standard model Higgs boson and other pseudoscalar mesons which can be enhanced because of large number of KK modes in models with right handed singlet neutrinos in large extra dimensions. We find that the invisible decay rate of Higgs can be as large as $H\to b \bar b $ decay rate only for a very restricted region of parameter space. This parameter space is even further restricted if one demands that the dimensionless neutrino Yukawa coupling $ł$ is O(1). We have also studied the scenarios where si…
The search for dark matter (DM) at colliders is founded on the idea of looking for something invisible. There are searches based on production and decay processes where DM may reveal itself as missing energy. If nothing is found, our best tool to constrain the parameter space of many extensions of the Standard Model (SM) with a DM candidate is the Higgs boson. As the measurements of the Higgs couplings become increasingly precise, higher-order corrections will start to play a major role. The tree-level contribution to the invisible decay width provides information about the portal coupling. Hi…
We study the invisible scalar of $S$ in charmed meson and baryon decays with flavor-changing neutral currents (FCNCs) based on the model-independent effective Lagrangian between the quarks and invisible scalar. From the bounds of the coupling constants extracted from the recent BES III experiment on the decay of $D^{0}\toπ^{0}\barνν$, we predict that the decay branching ratios of $D^{+}\toπ^{+}S$, $D_s^+\to K^+S$, $Λ_c\to pS$, $Ξ_c^{0(+)}\to Σ^{0(+)}S$, and $Ξ_c^0\toΛS$ can be as large as $10.6,~2.53,~2.39,~0.963,~5.77$, and $2.92\times10^{-4}$ with $m_{_S}\approx 1.1~{\rm GeV}$, respectively.…
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）
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…
We reconsider decays of pseudoscalar mesons (P) to neutrino pairs and possibly additional photons in presence of (light) Majorana neutrinos. For this purpose we derive a model-independent general parametrization of neutrino mass matrices with physically interpretable and irreducible set of parameters. The parametrization is valid for any number of neutrinos and interpolates smoothly between the heavy Majorana and the (pseudo)Dirac neutrino limits. We apply the new parametrization to the study of $P \rightarrow νν$ and $P \rightarrow ννγ$ decays within the SM extended by additional singlet ferm…
A class of extra dimensional models with a warped metric predict tunneling of a massive particle localized on our brane and escaping into additional dimensions. The experimental signature of this effect is the disappearance of the particle from our world, i.e. the particle $\to invisible$ decay. We point out that measurements of $Z\prime \to invisible$ decay width of a new heavy gauge boson $Z\prime$ at the CERN LHC can be effectively used to probe the existence of large extra dimensions. This result enhances motivations for a more sensitive search and study for this decay mode and suggests ad…
Motivated by the experimental study of $J/ψ\toγ~+$ invisible decay by the CLEO Collaboration, we analyze the process $J/ψ\to γν\barν$, as the standard model background for this invisible decay, at the lowest order. Our investigation shows that Br($J/ψ\to γν\barν$) is far below the present experimental upper limit on the branching ratio of $J/ψ\toγ~+$ invisible, which indicates that some interesting room for new physics in this channel might be expected. We also present a similar analysis of the $η_c\to γν\barν$ decay.
We probe for evidence of invisible neutrino decay in the latest NOvA and T2K data. It is seen that both NOvA and T2K data sets are better fitted when one allows for invisible neutrino decay. We consider a scenario where only the third neutrino mass eigenstate $ν_3$ is unstable and decays into invisible components. The best-fit value for the $ν_3$ lifetime is obtained as $τ_{3}/m_{3} = 3.16\times 10^{-12}$ s/eV from the analysis of the NOvA neutrino data and $τ_{3}/m_{3} = 1.0\times 10^{-11}$ s/eV from the analysis of the T2K neutrino and anti-neutrino data. The combined analysis of NOvA and T2…
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 …
If in a supersymmetric model, the lightest chargino is nearly degenerate with the lightest neutralino, the former can decay into the latter alongwith a soft pion (or a lepton-neutrino pair). Near degeneracy of the chargino and neutralino masses can cause the other decay products (the pion or the lepton) to be almost invisible. Photon-photon colliders offer a possibility of clean detection of such an event through a hard photon tag.
The hypothesis of the decay of neutrino mass eigenstates leads to a substantial modification of the appearance and disappearance probabilities of flavor eigenstates. We investigate the impact on the standard oscillation scenario caused by the decay of the heaviest mass eigenstate $ν_3$ (with a mass $m_3$ and a mean life $τ_3$) to a sterile state in DUNE. We find that the lower bound of $5.1 \times 10^{-11}~s/eV$ at 90\% CL on the decay parameter $τ_3/m_3$ can be set if the Neutral Current data are included in the analysis, thus providing the best long-baseline expected limit so far. We also sh…
This document is meant to provide semi-quantitative arguments to evaluate the luminosity needed at ILC to achieve a precise measurement of the Higgs mass, width and invisible decays. It is shown that for mH=120 GeV, one can save an order of magnitude on the luminosity needed to achieve a given precision on the Higgs mass, as compared to what can be obtained at \sqrt s=350 GeV, by running near threshold. Since the recoil mass resolution near threshold is independent of the Higgs mass, one can also access the Higgs width for masses above 170 GeV. This strategy of running just above threshold is …
The decay $K_L \to invisible$ has never been experimentally tested. In the Standard Model (SM) its branching ratio for the decay into two neutrinos is helicity suppressed and predicted to be $Br(K_L \to ν\barν) \lesssim 10^{-10}$. We consider several natural extensions of the SM, such as two-Higgs-doublet (2HDM), 2HDM and light scalar, and mirror dark matter models, those main feature is that they allow to avoid the helicity suppression factor and lead to an enhanced $Br(K_L \to invisible)$. For the decay $K_L \to ν\barν$ the smallness of the neutrino mass in the considered 2HDM model is expla…
In large extra dimension models the presence of an interaction between the Ricci scalar curvature and the Higgs doublet of the Standard Model can give rise to an invisible decay of the Higgs to Kaluza Klein graviscalars. The corresponding invisible width can cause a suppression of the LHC rates of a light Higgs in the visible channels below 5 sigma in some regions of the parameter space of the model. However in such regions the Higgs can be discovered through its invisible decay. The combination of the measurements done at the LHC and the LC can determine to some accuracy the parameters of the…
We investigate nucleon decays to light invisible fermion mediated by the coloured scalar $\bar S_1= (\bar 3, 1, -2/3)$ and compare them with the results coming from the mediation of $S_1 = (\bar 3,1,1/3)$. In the case of $\bar S_1= (\bar 3, 1, -2/3)$ up-like quarks couple to the invisible fermion, while in the case of $S_1 = (\bar 3,1,1/3)$ the down-like quarks couple to the invisible fermion. For the mass of invisible fermion smaller than the mass $m_p - m_K$, proton (neutron) can decay to $K$ and invisible fermion and the masses of $\bar S_1$ and $S_1$ are in the region $\sim 10^{15}$ GeV. T…
The flavor-changing neutral current decay processes of the $B$ and $B_c$ mesons with the final states involving spin-$1/2$ particles are investigated. By considering the background of the Standard Model where $ν\barν$ contributes the missing energy and the experimental upper bounds for the branching fractions, we get the constraints of the coupling constants of the quark-antiquark and the assumed invisible particles $χ\barχ$. The constraints of the coupling constants are then used to study the similar processes of the $B_c$ meson. At some specific region of $m_χ$, the upper limit of BR($B_c\to…
A search for the invisible decays of $ω$ and $ϕ$ mesons in $J/ψ\to ω(ϕ)η$ transitions has been performed by the BESIII Collaboration very recently. Inspired by this experimental study, we compute the lowest order contribution to branching ratios of ${\cal B}(V\to\barνν)$ with $V$ denoting $ρ,\;ω,\;ϕ$, as the standard model background to these invisible decays. Our predictions are far below the upper bounds given by the BESIII experiment. We also analyze the $J/ψ\to η(η^\prime)\barνν$ processes, and estimate their decay rates. Furthermore, the invisible decays of light pseudoscalar mesons $P$ i…
