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Search for $\eta$ and $\eta'$ Invisible Decays in $J/\psi\to\phi\eta$ and $\phi\eta'$
Abstract
Using a sample of $(225.3\pm 2.8)\times 10^{6}$ $J/\psi$ decays collected
with the BESIII detector at BEPCII, searches for invisible decays of $\eta$ and
$\eta^\prime$ in $J/\psi\to\phi\eta$ and $\phi\eta^\prime$ are performed.
Decays of $\phi \to K^{+}K^{-}$ are used to tag the $\eta$ and $\eta^\prime$
decays. No signals above background are found for the invisible decays, and
upper limits at the 90% confidence level are determined to be
$2.58\times10^{-4}$ for the ratio
$\frac{\mathcal{B}(\eta\to\rm{invisible})}{\mathcal{B}(\eta\to\gamma\gamma)}$
and $2.39\times10^{-2}$ for
$\frac{\mathcal{B}(\eta^\prime\to\rm{invisible})}{\mathcal{B}(\eta^\prime
\to\gamma\gamma)}$.
... The idea that certain configurations of flavor, spin and isospin of the two quarks inside the hadron have an important impact on its structure, has been discussed since a long time [129]. In particular, the effects on and structures are outlined in Ref. [130]. However, it is difficult to draw definite conclusions from CLEO, since all data points coincided with charmonium resonances , and . ...
... Decays of light mesons produced at BESIII can also probe new light particles [129]. In the case of dark photons, the general rule is that if light mesons can decay into regular photons then they can also decay into dark photons [115,130]. Since low-energy electron-positron colliders produce numerous mesons, it is also possible to investigate dark photons in rare decays of mesons. For instance, one can search for a resonance in the processes and . ...
... Electron-positron colliders are suitable for probing dark photons via either the direct production or rare decays of mesons (see Sect. 6.5). Dark photons, directly produced in annihilation, could subsequently decay into charged leptons [116,130,[135][136][137], which could be detected at BESIII. In comparison with the irreducible QED background, dark photon production is highly suppressed. ...
There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics. This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESIII and B factories, and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X (1835) meson state at BESIII, as well as the threshold measurements of charm mesons and charm baryons.
We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESIII during the remaining operation period of BEPCII. This survey will help in the optimization of the data-taking plan over the coming years, and provides physics motivation for the possible upgrade of BEPCII to higher luminosity.
... One possibility to probe the leptophobic dark sector is to use neutrino or beam dump experiments [29][30][31][32]. Another possibility is to look for invisible decays of neutral mesons into dark sector particles at e þ e − colliders [33,34]. Experimental studies of invisible decays of neutral hadrons were performed by several collaborations. ...
... Experimental studies of invisible decays of neutral hadrons were performed by several collaborations. In particular, the BES III collaboration [34,35] set constraints on the branching fraction of the invisible decays of η, η 0 , ω, and ϕ mesons. The BABAR Collaboration [36,37] has studied the invisible decay modes of heavy quarkonia. ...
We consider an experiment to search for dark sector particles in invisible (or semi-invisible) decays of neutral mesons M0=π0, η, η′, ω, f2(1270), which produced the charge-exchange reactions π−+(A,Z)→M0+(A,Z−1);M0→ invisible of high-energy pions (or kaons) on a nuclei target in the NA64 experiment at the CERN SPS. This reaction chain would lead to a striking signature of the signal event—the complete disappearance of the beam energy in the setup [Phys. Rev. D 91, 015004 (2015)]. Using data obtained from the measurements at IHEP (Protvino) and Fermilab (Batavia) we show that the integral cross sections σ for the production of the M0 s slightly deviate from the phenomenological formula σ∼Z2/3, where Z is the nuclei charge. In particular, we present the formulas for the differential and integral cross sections that explicitly depend on the Mandelstam and Z variables. Derived formulas are used to predict the M0 yield as a function of beam energy for several target nuclei, and to estimate the projection sensitivity for the proposed search in the dark vector portal model. Sensitivity to different decay modes of M0s is explored.
... These limits are still above the standard model (SM) predictions [3]. For the light mesons like pseudoscalar P with P denoting π 0 , η, η 0 , the current experimental upper bounds have been given by the E949 Collaboration [4] for π 0 → invisible decays and by the BESIII Collaboration [5] for ηðη 0 Þ → invisible decays, while branching ratios of these pseudoscalar invisible decays were calculated in Ref. [6] a long time ago. ...
... have been determined, at the 90% confidence level, by the BESIII Collaboration [5]. Recently, an interesting experimental project, by searching for invisible decays of π 0 ,η, η 0 , K S , and K L to probe new physics, has been proposed [18] and is designed for the NA64 experiment at the CERN Super Proton Synchrotron. ...
A search for the invisible decays of ω and ϕ mesons in J/ψ→ω(ϕ)η transitions was performed by the BESIII Collaboration very recently. Inspired by this experimental study, we compute the lowest-order contribution to branching ratios of B(V→ν¯ν) 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→η(η′)ν¯ν processes and estimate their decay rates. Furthermore, the invisible decays of light pseudoscalar mesons P including π0, η, and η′ are reexamined in the present paper. It is shown that, due to the helicity suppression of the two-neutrino final state, the standard model contributions to P→invisible decays are dominated by P→ν¯νν¯ν processes.
... Experimental studies of invisible hadronic decays were performed by several collaborations. In particular, the BES III Collaboration [23,24] set the constraints on the invisible branching fraction of the η, η 0 , ω, and ϕ mesons. The BABAR Collaboration [25,26] studied the invisible decay modes of heavy quarkonia. ...
We test a novel idea of using a π− beam in the fixed-target experiments to search for new physics in the events with missing energy. Bounds for invisible vector ρ meson decay were derived, analyzed, and compared with the current limits on searching dark matter in the accelerator based experiments. We demonstrate that the new approach can be effective tool to probe sub-GeV dark matter parameter space.
... As a complementary study, we concentrate on FCNC effects arising from the dark photon with the c and u quarks, where the missing energy due to the dark photon is the feature of the signal processes. BESIII has searched for the invisible signals within various hadron decays, including η=η 0 → invisible [17], ω=ϕ → invisible [18], Λ → invisible [19] and J=ψ → γ þ invisible [20], and no significant signals are observed. However, this has never been probed in the charmed baryon sector. ...
A search for a massless dark photon γ′ is conducted using 4.5 fb−1 of e+e− collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. No significant signal is observed, and the upper limit on the branching fraction B(Λc+→pγ′) is determined to be 8.0×10−5 at 90% confidence level.
... Electron-positron collision experiments such as BESIII and Belle II have the ability to probe invisible decays, benefiting from a welldefined production process and a clean reaction environment. Stringent limits on the invisible decays of ϒ [34], J=ψ [35], B 0 [36], η ð0Þ [37], π 0 [38], D 0 [39], ω [40], and ϕ [40] mesons have already been determined by several experiments. However, no experimental study of invisible baryon decays has been carried out yet. ...
A search for invisible decays of the Λ baryon is carried out in the process J/ψ→ΛΛ¯ based on (1.0087±0.0044)×1010 J/ψ events collected with the BESIII detector located at the BEPCII storage ring. No signals are found for the invisible decays of Λ baryon, and the upper limit of the branching fraction is determined to be 7.4×10-5 at the 90% confidence level. This is the first search for invisible decays of baryons; such searches will play an important role in constraining dark sector models related to the baryon asymmetry.
... But the attention to possible invisible decays in hadrons made of light quarks [5] has been much more scarce than one would think. Early measurements of invisible decays on short-lived light mesons of π 0 [6] and η (η ′ ) [7] were attempted. ...
Invisible decays of neutral hadrons are evaluated as ordinary-mirror particle oscillations using the newly developed mirror matter model. Assuming equivalence of the $CP$ violation and mirror symmetry breaking scales for neutral kaon oscillations, rather precise values of the mirror matter model parameters are predicted for such ordinary-mirror particle oscillations. Not only do these parameter values satisfy the cosmological constraints, but they can also be used to precisely determine the oscillation or invisible decay rates of neutral hadrons. In particular, invisible decay branching fractions for relatively long-lived hadrons such as $K^0_L$, $K^0_S$, $\Lambda^0$, and $\Xi^0$ due to such oscillations are calculated to be $9.9\times 10^{-6}$, $1.8\times 10^{-6}$, $4.4\times 10^{-7}$, and $3.6\times 10^{-8}$, respectively. These significant invisible decays are readily detectable at existing accelerator facilities.
Electron beam fixed target experiments such as NA64 and LDMX use missing energy-momentum to detect the production of dark matter and other long-lived states. The most studied production mechanism is dark Bremsstrahlung through a vector mediator. In this work, we explore a complementary source of missing energy-momentum signals: Bremsstrahlung photons can convert to hard vector mesons in exclusive photoproduction processes, which then decay to dark matter or other invisible particles, such as neutrinos. We find that existing NA64 data can improve the leading constraints on invisible light vector meson decays, while a future run of LDMX could improve them by up to 5 orders of magnitude. For the examples of a dark photon and a U(1)B gauge boson mediator, accounting for meson decays substantially enhances these experiments’ sensitivity, especially to thermal relic dark matter of mass mχ≳0.1 GeV.
The world's largest sample of J/ψ events, 1.31 billion events accumulated at the BESIII detector, provides a unique opportunity to investigate η and η′ physics via two-body J/ψ radiative or hadronic decays. For many η′ decay channels the low background data samples are up to three orders of magnitude larger than collected in any previous experiment. Here we review the most significant results on η and η′ obtained at BESIII so far. The analyses range from detailed studies of common decay dynamics, observations of new radiative and Dalitz decays, and searches for rare/forbidden decays with sensitivity up to bernou ∼ 10⁻⁵. Finally, prospects of forthcoming runs at the J/ψ peak for η and η′ physics are discussed. © 2018 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
Using a sample of 448.1×106 ψ(3686) events collected with the BESIII detector, a search for the isospin violating decay ηc→π+π−π0 via ψ(3686)→γηc is presented. No signal is observed, and the upper limit on B(ψ(3686)→γηc)×B(ηc→π+π−π0) is determined to be 1.6×10−6 at the 90% confidence level. In addition, a search for η(1405)→f0(980)π0 in ψ(3686) radiative decays is performed. No signal is observed, and the branching fraction B(ψ(3686)→γη(1405))×B(η(1405)→f0(980)π0)×B(f0(980)→π+π−) is calculated to be less than 5.0×10−7 at the 90% confidence level.
This paper will discuss the design and construction of BESIII, which is designed to study physics in the tau-charm energy region utilizing the new high luminosity BEPCII double ring e(+)e(-) collider. The expected performance will be given based on Monte Carlo simulations and results of cosmic ray and beam tests. In BESIII, tracking and momentum measurements for charged particles are made by a cylindrical multilayer drift chamber in a 1 T superconducting solenoid. Charged particles are identified with a time-of-flight system based on plastic scintillators in conjunction with dE/dx (energy loss per unit pathlength) measurements in the drift chamber. Energies of electromagnetic showers are measured by a Csl(Tl) crystal calorimeter located inside the solenoid magnet. Muons are identified by arrays of resistive plate chambers in a steel magnetic yoke for the flux return. The level 1 trigger system, data acquisition system and the detector control system based on networked computers will also be described.
The number of J/ψ events collected with the BESIII detector at the BEPCII from June 12 to July 28, 2009 is determined to be (225.3±2.8) × 106 using J/ψ →inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
We present the new coherent exclusive exponentiation (CEEX), the older exclusive exponentiation (HEX), and the semianalytical inclusive exponentiation (IEX) for the process e~e-4>ff+ny, where / = fj.,T,d,u,s,c,b, which are valid for center-of-mass energies from the -4 lepton threshold to 1 TeV, that is, for CERN LEP1, LEP2, the SLC, future linear colliders, and b,c,r factories, etc. The approaches are based on Yennie-Frautschi-Suura exponentiation. In CEEX, the effects due to photon emission from initial beams and butgoing fermions are calculated in QED up to second order, including all interference effects. Electroweak Corrections are included to first order, at the amplitude level. Beams can be polarized longitudinally and transversely, and all spin correlations are incorporated in an exact manner. The EEX is more primitive, lacks initial-final interferences, but it is valuable for testing the newer CEEX. The IEX provides us with a set of sophisticated semianalytical formulas for the total cross section and selected inclusive distributions, which are mainly used for cross-checks of the Monte Carlo results. We analyze numerical results at the Z peak, 189 GeV and 500 GeV for simple kinematical cuts (comparisons with inclusive exponentiation) and for realistic experimental cuts. The physical precision and technical precision are determined for the total cross section and for the charge asymmetry.
A study of the reactions pp → pfps(K+K- π+π-) and pp → pfps(K+ K- π+π- π0) shows evidence for the K * (892) K̄ * (892) and φω channels respectively. The K * (892) K̄ * (892) mass spectrum shows a broad distribution with a maximum near threshold and an angular analysis shows that it is compatible with having Jp = 2+. The behaviour of the cross-section as a function of centre of mass energy, and the four momentum transfer dependence, are compatible with what would be expected if the K * (892) K̄ * (892) system was produced via double Pomeron exchange. The dPT behaviour of the φω channel is similar to what has been observed for all the undisputed qq states. In contrast, the qq̄ behaviour of the K * (892) K̄ * (892) final state is similar to what has been observed for the φφ final state and for previously observed glueball candidates.
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter.A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/.The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D.This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).
In the development of atomic physics the interaction of atoms with electromagnetic radiation has been of paramount importance for the understanding of atomic structure. In the case of nuclei, this interaction has not been so important a tool, since, unlike the atomic case, the wavelengths of interest are so short that they cannot be measured by the usual optical devices. The rather indirect methods which must be employed make the energy determination quite inaccurate compared to spectroscopic standards, and the available resolution low. Furthermore in most cases the radiation process is only one of many competing processes (such as particle emission or sometimes even beta-decay) and its probability is correspondingly lower.
A partial wave analysis is presented of and from a sample of 58M events in the BES II detector. The is observed clearly in both sets of data, and parameters of the Flatté formula are determined accurately: , , . The data also exhibit a strong ππ peak centred at . It may be fitted with and a dominant signal made from interfering with a smaller component. There is evidence that the signal is resonant, from interference with . There is also a state in ππ with and ; spin 0 is preferred over spin 2. This state, , is distinct from . The data contain a strong peak due to . A shoulder on its upper side may be fitted by interference between and .
The diffractive dissociation of a 200-GeV/c π- beam into
K0SK0Sπ+π-π-
has been observed. The diffractive
K0SK0Sπ+π-π-
cross section is 1.59+/-0.78 μb. The ratio of the diffractive
K0SK0Sπ+π-π-
cross section to the diffractive
K0SK0Sπ- cross
section is 0.40+/-0.13, which is in good agreement with a
diffractive-fragmentation-model prediction of 0.36. There is evidence
for simultaneous production of K*- and K*+ in the
diffractive
K0SK0Sπ+π-π-
sample. The K*+-K0Sπ-+
mass distribution shows an enhancement near 1.95 GeV.
We have developed a Monte Carlo generator for simulating charmonium
J/ψ and ψ(2S) inclusive decay. In the model, charmonium decay
via gluons is described by the QCD partonic theory, and the partonic
hadronization is handled by the LUND model. Extended C- and G-parity
conservation are assumed and abnormal suppression effects of charmonium
decay are included. This model reproduces the properties of hadronic
events in the charmonium inclusive decay, such as the branching ratios
of hadronic resonance, the ratios of stable hadrons and the radiative
products, and as the global properties of hadronic events.
The authors have searched with the crystal ball detector for axionlike particles in radiative J/psi decays. An upper limit on the branching ratio B(J/psi..--> gamma..+a)<1.4 x 10/sup -5/ (90% C.L.) is obtained. This result holds for long-lived, noninteracting pseudoscalar or vector particles of mass less than 1 GeV. Thus, this experiment also places stringent limits on the existence of other possible light bosons such as those arising in supersymmetric theories.