Search

This paper describes the search for di-photon decays of an Axion-like particle (ALP) in radiative decays of J/ψ using 2.7 billion ψ(2S) events collected by the BESIII detector. A J/ψ data sample is selected by tagging the pion-pair from ψ(2S)→π+π−J/ψ transition. No evidence of ALP production is found, and 95% confidence upper limits on ALP photon coupling are set to be in the mass range of [0.165, 2.84] GeV/c2. The new BESIII limits are more stringent than the existing experimental constraints. [ABSTRACT FROM AUTHOR]

In this work, the spectra and decay properties of B c mesons (c b ¯ ) have been investigated using a nonrelativistic potential model incorporating corrections from LQCD. The nonrelativistic Schrödinger wave equation is solved numerically using the Matrix Numerov Method. Using the obtained masses and wave functions, decay widths, lifetime, branching ratios and radiative decay widths are computed for the c b ¯ system. Influence of the bound state effect on decay width of B c mesons is also analyzed. We compare the obtained results with the experimental data and with other theoretical models. [ABSTRACT FROM AUTHOR]

We study the production cross-sections and radiative decay widths of heavy quarkonia (charmonia and bottomonia) in magnetized nuclear matter. The production cross-sections of the ψ (3 7 7 0) and ϒ (4 S) , from the D D ̄ and B B ̄ scatterings, respectively, are studied from the medium modifications of the masses and partial decay widths to open charm (bottom) mesons, of these heavy flavor mesons. Within a chiral effective model, the masses of the vector and pseudoscalar charmonium (bottomonium) states are calculated from the medium modification of a dilaton field, χ , which mimics the gluon condensates of quantum chromodynamics (QCD). The effects of the Dirac sea (DS) and the anomalous magnetic moments (AMMs) of the nucleons are taken into consideration in this study. In the presence of a magnetic field, there is mixing of the pseudoscalar (P) meson and the longitudinal component of the vector (V) meson (PV mixing), which leads to appreciable modifications of their masses. The radiative decay widths of the vector (V) heavy quarkonia to the pseudoscalar (P) mesons (J / ψ → η c (1 S) γ , ψ (2 S) → η c (2 S) γ and ψ (1 D) → η c (2 S) γ for the charm sector and ϒ (N S) → η b (N S) γ , N = 1 , 2 , 3 , 4 , for the bottom sector) in the magnetized asymmetric nuclear matter are also investigated in this work. The difference in the mass of the transverse component from the longitudinal component of the vector meson, arising due to PV mixing, is observed as a double peak structure in the invariant mass spectrum of the production cross-section of ψ (3 7 7 0). This is observed to be appreciably more pronounced as the value of the magnetic field is increased. For the bottomonium (ϒ (4 S)) production cross-section, the effect of the PV mixing effect is observed to be marginal, and there is observed to be a downward shift in the peak position due to the DS contributions. The modifications of the production cross-sections as well as the radiative decay widths of the heavy quarkonia in the magnetized matter should have observable consequences on the production of these heavy flavor mesons resulting from ultra-relativistic peripheral heavy ion collision experiments, where the created magnetic field can be extremely large. [ABSTRACT FROM AUTHOR]

In this work, we tried to predict the parameters of B c ∗ meson. Simple assumptions gave us the following parameters m B c ∗ = 6 3 2 9 ± 1 0 MeV and f B c ∗ = 5 3 5. 5 ± 5 7. 8 MeV (for Λ B c ∗ = 2. 2 6 ± 0. 1 4 GeV in covariant confined quark model). We calculated widths of radiative decays of B q ∗ mesons, where q = u ∕ d , s , c and compared them with other theoretical works. It was shown that the width of the B c ∗ meson is very sensitive to the mass m B c ∗ as expected and less to the size parameter Λ B c ∗ . [ABSTRACT FROM AUTHOR]

The mass spectrum of b b ̄ states has been obtained using the phenomenological relativistic quark model (RQM). The Hamiltonian used in the investigation has confinement potential and confined one gluon exchange potential (COGEP). In the framework of RQM a study of M 1 and E 1 radiative decays of b b ̄ states has been made. An overall agreement is obtained with the experimental masses and decay widths. The possibility that some of the excited s wave b b ̄ states being exotic states is explored. [ABSTRACT FROM AUTHOR]

The mass spectra and decay properties of B and B s mesons are obtained using the nonrelativistic potential model by applying the variational approach. The quark–anti-quark potential used in our model consists of a Hulthen potential and a confining linear potential. The hyper-fine interaction is introduced to obtain the splittings of the spin-singlet and triplet states, while the spin–orbit and tensor interactions provide the fine structure splittings. The model parameters and the wave functions that reproduce the mass spectra are used to investigate the decay properties of B and B s mesons. The mass spectra of B and B s mesons have been enhanced using coupled channel effects. [ABSTRACT FROM AUTHOR]

An enhanced phenomenological model that includes isospin-symmetry breaking is presented in this letter. The model is then used in a number of statistical fits to the most recent experimental data for the radiative transitions VPγ (V=ρ, K⁎, ω, ϕ and P=π, K, η, η′) and estimations for the mixing angles amongst the three pseudoscalar states with vanishing third-component of isospin are obtained. The quality of the performed fits is good, e.g. χmin2/d.o.f=1.9. The current experimental uncertainties allow for isospin-symmetry violations with a confidence level of approximately 2.5σ.

The 2S B c states observed by ATLAS, CMS and LHCb Collaborations are discussed. The observation perspectives of B c ∗ , 2P wave, 3P wave and D wave states of B c at LHC experiments are estimated. [ABSTRACT FROM AUTHOR]

We investigate B s 0 → ℓ + ℓ − γ decays in a nonuniversal Z ′ model derived from the extension of the Standard Model (SM). Considering the Z ′ -mediated flavor-changing neutral current (FCNC) effects, we calculate the branching ratio and forward–backward asymmetry (A FB ) for B s 0 → ℓ + ℓ − γ decay processes. We compare the obtained results with predictions of the SM and discuss the sensitivity of the observables to Z ′ boson coupling parameters. We find that the branching ratios are enhanced by one order from SM predictions in Z ′ model scenario. We also observe that the variation of forward–backward asymmetry with the Z ′ boson coupling parameters portrays discrimination between NP effects and SM results. [ABSTRACT FROM AUTHOR]

The description of the radiative decays of $V \to P \gamma^*$ in different forms Poincaré invariant quantum mechanics (PIQM) is considered. To construct the matrix element of the electromagnetic current we use the non-diagonal parametrization procedure. The obtained matrix element of the current satisfies the conditions of the Lorentz covariance and conservation. To illustrate this approach in a modified relativistic impulse approximation the description of the radiative transition $\rho \to \pi \gamma^{*}$ is performed. An analytic expression for the transition form factor $F_{\pi \rho}(Q^2)$, matching all forms PIQM, is obtained. Numerical calculations of the transition form factor are made with different model wave functions.

We study the production of the light J P C = 1 − + hybrid isoscalars η 1 ′ (1855) and the yet undiscovered η 1 (1660) as intermediate states in the radiative decays of the charmonium (J / ψ) to two conventional mesons using a flavor symmetric Lagrangian. For this purpose, we use the J / ψ → γ η 1 ′ (1855) → γ η η ′ process as the reference. We find that some of the decay channels have branching ratios similar to or larger than that of the γ η η ′ channel and are sensitive to the mixing between the hybrid isoscalars. We propose that relatively stable γ η f 1 (1285) channel be explored for the presence of the light hybrid isoscalar η 1 h y b (1660). We also exploit the strong decay channels containing at least one vector meson to study the radiative decays of the whole hybrid nonet { π 1 (1600) , K 1 h y b (1750) , η 1 h y b (1660) , η 1 ′ (1855) }. We find that the hybrids cannot radiatively decay into the I = 0 pseudoscalars. Furthermore, the vector decay channels ((ρ / ω / ϕ) γ) of the hybrid isoscalars are sensitive to the strangeness content of the hybrids. We also provide estimates for the branching fractions for the radiative production and partial widths for the radiative decays of the hybrids. [ABSTRACT FROM AUTHOR]

A new technique for searching radiative decays of the ϒ(1S) resonance in the charmonium state is discussed. It is based on tagging the ϒ(1S) resonance in hadron transitions ϒ(2S) → ϒ(1S)π+π− using the data sample obtained at B factories, i.e., in experiments at e+e− colliders for studying B mesons at the center-of-mass energy equal to the mass of the ϒ(2S) resonance. Simulation estimates show that the use of the proposed method in the Belle experiment will make it possible to increase the sensitivity in the study of the radiative decays of the ϒ(1S) resonance in the charmonium states by an order of magnitude. [ABSTRACT FROM AUTHOR]

The transition form factors responsible for the radiative Σ Q → Λ Q γ and Ξ Q ′ → Ξ Q γ decays of the negative parity baryons are examined within light cone QCD sum rules. The decay widths of the radiative transitions are calculated using the obtained results of the form factors. A comparison of our predictions on decay widths with the corresponding widths of positive parity baryons is given. [ABSTRACT FROM AUTHOR]

Precise measurements on rare radiative B decays are performed with the LHCb experiment at LHC. The LHCb results regarding the ratio of branching fractions for two radiative decays, B → K γ and B → ϕ γ, the direct CP asymmetry in B → K γ decay channel and the observation of the photon polarization in the B → K ππ γ decay, are included. The first two measurements were performed in 1 fb of pp collisions data and the third one in 3 fb of data, respectively. [ABSTRACT FROM AUTHOR]

Using the inclusive photon spectrum based on a data sample collected at the J / ψ peak with the KEDR detector at the VEPP-4M e + e − collider, we measured the rate of the radiative decay J / ψ → γ η c as well as η c mass and width. Taking into account an asymmetric photon lineshape we obtained Γ γ η c 0 = 2.98 ± 0.18 − 0.33 + 0.15 keV , M η c = 2983.5 ± 1.4 − 3.6 + 1.6 MeV / c 2 , Γ η c = 27.2 ± 3.1 − 2.6 + 5.4 MeV . [ABSTRACT FROM AUTHOR]

The first radial excitations of axial-vector mesons are considered in the framework of the extended U(3) × U(3) Nambu-Jona-Lasinio model. We calculate the mass spectrum of a1, f1 and also strange axial-vector mesons. For description of radially excited states, we used the form factors of polynomial type of the second order in transverse quark momentum. For the ground- and excited-state mesons consisting of light quarks we have calculated the widths of a number of strong and radiative decays. We got satisfactory agreement with experimental data for the ground states. A set of predictions for the excited states of mesons is given. [ABSTRACT FROM AUTHOR]

In the extended NJL model the radiative decay widths of the radially excited states of the pseudo-scalar π, η, and η′ mesons are calculated. The predictions for the decay widths of the processes π(1300) → (ρ, ω)γ, η(1295) → (ρ, ω, φ)γ, and η(1475) → (ρ, ω, φ)γ are given. Nowadays, there are no solid experimental data for these processes. The comparison of the results obtained in the framework of the standard and the extended NJL models for decays of the ground states of mesons is given. It is shown that these calculations correspond to each other and are also in satisfactory agreement with experimental data. This allows one to expect that the extended NJL can give reliable predictions for the excited states of mesons. [ABSTRACT FROM AUTHOR]

In this article, we study the radiative transitions among the vector and scalar heavy quarkonium states with the covariant light-front quark model. In calculations, we observe that the radiative decay widths are sensitive to the constituent quark masses and the shape parameters of the wave-functions, and reproduce the experimental data with suitable parameters. [ABSTRACT FROM AUTHOR]

Through-space charge-transfer (TSCT) emitters with high radiative decay rates are very important for their use in electroluminescent devices but have rarely been reported. Here, three TSCT emitters 1 – 3 with high radiative decay rates of over 107 s−1 are developed by using 4-methyl-9 H -xanthene (MeXT) as the rigid linker, 10-phenyldihydroacridine (PhDMAC) as the donor, and 2,4,6-triphenyltriazine (1), 2,4,6-triphenylpyrimidine (2) and 2,4-di- tert -butyl-6-phenyl-1,3,5-triazine (3) as the acceptors. Single-crystal structures and theoretical calculations reveal that the donor fixed by the spiro-structure in MeXT and the acceptor located nearby the donor are arranged into a very close, cofacial packing with strong through-space electronic interactions, which promotes TSCT and the radiative decay of charge-transfer state. In degassed toluene solution, 1 – 3 show blue emission centered at 479, 458 and 455 nm, respectively, and afford high radiative decay rates (k r,s) of up to 1.6 × 107 s−1, which are the highest for TSCT emitters reported so far. In the doped films, 1 – 3 show high k r,s values of up to 1.3 × 107 s−1 and high photoluminescent efficiencies (Φ PL) of up to 0.95. Organic light-emitting diodes using 1 – 3 as the emitters afford blue emission with high external quantum efficiencies of up to 22.6%. The work reveals that TSCT emitters with similar emission characteristics (high Φ PL and high k r,s) to through-bond charge-transfer emitters are achievable by arranging the donor and acceptor units into a very close, cofacial packing. • Through-space charge-transfer emitters were developed with a xanthene linker. • Very close, cofacial donor/acceptor packing was formed within the emitter. • High radiative decay rates up to 1.6 × 107 s−1 were achieved. • Organic light-emitting diodes using the emitters showed high EQE s of up to 22.6%. [ABSTRACT FROM AUTHOR]

In this paper, we perform an systematic study of the radiative transitions among the bottomonium states using the heavy quarkonium effective Lagrangians, and make predictions for the ratios among the radiative decay widths of a special multiplet to another multiplet. The predictions can be confronted with the experimental data in the future. [ABSTRACT FROM AUTHOR]

In this work, we have employed Bethe-Salpeter equation (BSE) under Covariant In-stantaneous Ansatz (CIA) to study radiative decays of light vector mesons through the process: h → h′ γ, taking h and h′ as equal mass light vector and pseudoscalar mesons, respectively. The decay widths calculated for these processes are in reasonable agree-ment with data. The motivation for this work was our intention to resolve the problems involved in calculations of triangle quark-loop diagrams which appear in processes such as radiative meson decays, meson form factors, strong decays of mesons, etc., in BSE un-der CIA, which give rise to complexities in amplitudes (as pointed out earlier in Ref. 1) due to the presence of the time-like momentum components in Gaussian factors asso-ciated with the vertex functions of the participating hadrons. In this work we try to highlight this problem and then demonstrate a mathematical procedure which might lead to calculations of such processes in BSE under CIA. [ABSTRACT FROM AUTHOR]

Abstract: Recent results and future prospects of particle physics experiments with neutral and charged -meson (kaon) decays are reviewed. Topics include CP violation, rare decays, leptons in kaon decays, tests of CPT and quantum mechanics, radiative decays, hadrons in kaon decays, basic observables, and CKM unitarity, and exotic searches. Experimental techniques developed for the kaon decay experiments are discussed. [Copyright &y& Elsevier]

We determine the value of the ω-ρ-π mesons coupling (gωρπ), in the context of the vector meson dominance model, from radiative decays, the ω→3π decay width and the e+e-→3π cross-section. For the last two observables we consider the effect of either a heavier resonance (ρ′(1450)) or a contact term. A weighted average of the results from the set of observables yields gωρπ = 14.7±0.1 -1 in absence of those contributions, and gωρπ = 11.9 ± 0.2 -1 or gωρπ = 11.7 ± 0.1 -1 when including the ρ′ or contact term, respectively. The inclusion of these additional terms makes the estimates from the different observables to lay in a more reduced range. Improved measurements of these observables and the ρ′(1450) meson parameters are needed to give a definite answer on the pertinence of the inclusion of this last one in the considered processes. [ABSTRACT FROM AUTHOR]

In this article, we study the radiative decays among the charmonium states with the heavy quark effective theory, and make predictions for the ratios among the radiative decay widths of an special multiplet to another multiplet. The predictions can be confronted with the experimental data in the future and put additional constraints in identifying the X, Y, Z charmonium-like mesons. [ABSTRACT FROM AUTHOR]

Using the calculated values of the strong coupling constants of the heavy sextet spin-3/2 baryons to sextet and antitriplet heavy spin-1/2 baryons with light vector mesons within the light cone QCD sum rules method, and vector meson dominance assumption, the radiative decay widths are calculated. These widths are compared with the "direct" radiative decay widths predicted in the framework of the light cone QCD sum rules. [ABSTRACT FROM AUTHOR]

In the little Higgs model with T-parity (LHTM), the only tree-level kinematically allowed two-body decay of the ZH boson can be the ZH→AHH decay and thus one-loop induced two-body decays may have a significant rate. We study the ZH→γAH decay, which is induced at the one-loop level by a fermion triangle and is interesting as it depends on the mechanism of anomaly cancelation of the model. All the relevant two- and three-body decays of the ZH gauge boson arising at the tree-level are also calculated. We considered a small region of the parameter space where f is still allowed to be as low as 500 GeV by electroweak precision data. We analyzed the scenario of a Higgs with a mass of 120 GeV. We found that the ZH→γAH branching ratio can be of the order of a tree-level three-body decay and may be at the reach of detection at the LHC for f close to 500 GeV, but it may be difficult to detect for f = 1 TeV. There is also an scenario where the Higgs boson has an intermediate mass such that the ZH→AHH decay is closed, the ZH→γAH gets considerably enhanced and the chances of detection get a large boost. [ABSTRACT FROM AUTHOR]

We have employed the framework of Bethe-Salpeter equation under covariant instantaneous ansatz to calculate leptonic decay constants of unequal mass pseudoscalar mesons like π±, K, D, DS and B, and radiative decay constants of neutral pseudoscalar mesons like π0 and ηc into two photons. In the Dirac structure of hadronic Bethe-Salpeter wave function, the covariants are incorporated from their complete set in accordance with a recently proposed power counting rule. The contribution of both leading order and next-to-leading order Dirac covariants to decay constants are studied. The results are found to improve and hence validating the power counting rule which provides a practical means of incorporating Dirac covariants in the Bethe-Salpeter wave function for a hadron. [ABSTRACT FROM AUTHOR]

Abstract: Using an improved “analytic K-matrix model”, we reconsider the extraction of the and γγ widths from scatterings data of Crystal Ball and Belle. Our main results are summarized in Tables 3 and 4. The averaged σ “direct width” to γγ is 0.16(3) keV which confirms a previous result of Mennessier et al. (2007, 2008) and which does neither favour a large four-quark/molecule nor a pure components. The “direct width” of the of 0.28(2) keV is much larger than the four-quark expectation but can be compatible with a or a gluonium component. We also found that the rescattering part of each amplitude is relatively large indicating an important contribution of the meson loops in the determinations of the σ and γγ total widths. This is mainly due to the large couplings of the σ and to ππ and/or , which can also be due to a light scalar gluonium with large OZI violating couplings but not necessary to a four-quark or molecule state. Our average results for the total (direct + rescattering) γγ widths: , are comparable with the ones from dispersion relations and PDG values. Using the parameters from QCD spectral sum rules, we complete our analysis by showing that the production rates of unmixed scalar gluonia and agree with the data from , ϕ radiative and semi-leptonic decays. [ABSTRACT FROM AUTHOR]

Abstract: Within the framework of a nonlinear chiral Lagrangian we explore the nontrivial nature of and in terms of quarkonium, tetraquark and gluonium components. The mass constraints are obtained and the strong and radiative partial widths are calculated to demonstrate and discriminate these components. The static properties of and glueball are also studied. Our results are confronted with the experimental and theoretical data available as well as the upcoming measurements. [ABSTRACT FROM AUTHOR]

Abstract: We evaluate the radiative decay into a vector, a pseudoscalar and a photon of several resonances dynamically generated from the vector–vector interaction. The process proceeds via the decay of one of the vector components into a pseudoscalar and a photon, which have an invariant mass distribution very different from phase space as a consequence of the two vector structure of the resonances. Experimental work along these lines should provide useful information on the nature of these resonances. [Copyright &y& Elsevier]

Abstract: The decays of a light scalar meson into a vector meson and a photon are evaluated in the tetraquark and quarkonium assignments of the scalar states. A link with the radiative decays is established: experimental results for will make it possible to decide if the direct, quark-loop contribution to or the kaon-loop contribution is dominant. Also strong decays – where P denotes a pseudoscalar meson – are investigated: within our scheme, the tetraquark assignment works better than the quarkonium one. [Copyright &y& Elsevier]

We present the magnetic dipole(M1) transitions V → Pγ of various heavy-flavored mesons such as $(D, D^{*}, D_s, D^{*}_s, \eta_c, J/\psi)$ and $(B, B^{*}, B_s, B^{*}_s, \eta_b, \Upsilon)$ using the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. Our numerical results for the radiative decay widths are in good agreement with the available experimental data as well as other theoretical model calculations. [ABSTRACT FROM AUTHOR]

The quark-level linear σ model (LσM) is employed to compute a variety of electromagnetic and weak observables of light mesons, including pion and kaon form factors and charge radii, charged-pion polarizabilities, semileptonic weak Kℓ3 decays, semileptonic weak radiative pion and kaon form factors, radiative decays of vector mesons, and nonleptonic weak K2π decay. The agreement of all these predicted observables with experiment is striking. In passing, the tight link between the LσM and vector-meson dominance is shown. [Copyright &y& Elsevier]

Radiative magnetic dipole decays of heavy–light vector mesons into pseudoscalar mesons V→Pγ are considered within the relativistic quark model. The light quark is treated completely relativistically, while for the heavy quark the 1/mQ expansion is used. It is found that relativistic effects result in a significant reduction of decay rates. Comparison with previous predictions and recent experimental data is presented. [Copyright &y& Elsevier]