Predictions of duality for the charmed meson masses

The constraints of duality via FESR's are applied to the processes P+P→P+V, using particles with a new quantum number (charm) as both external and internal (resonance saturation) states. The results are independent of any detailed dynamics or symmetry schemes, as well as independent of coupling strengths. We use the masses of the recently-discovered D and D¹ to set the scale. We predict , m_F = 1938 ± 33 MeV, . Thus slopes of Regge trajectories for charmed mesons are predicted to be substantially smaller than those for ordinary mesons.     

Five quarks,new particles and V + A currents

We propose an SU(5) model for the new heavy mesons, with a charge $\text{?1}\text{3}$ fancy quark in addition to a charge $\text{+2}\text{3}$ charmed quark. Besides interpreting the two narrow vector mesons J/Ψ and Ψ′ as c$\text{c}$ and f$\text{f}$ bound states and accounting for present data in a natural way, the model has (i) three new fancy vector mesons in addition to the charmed ones of the SU (4) model, (ii) at most two new $\text{C = P = +}\text{mesons}\text{(}\text{c}\text{c}\text{,}{}^3\text{P}{}_{\mathrm{J}}\text{, J = 0, 1)}$ between J/Ψ and Ψ ′, with suppressed radiative decays $\text{Ψ′ →}{}^3\text{P}{}_{\mathrm{J}}\text{+ γ}$, (iii) a state near 4.6 GeV in e⁺e^?, decaying mostly to fancy mesons if it is broad or perhaps charmed mesons if it is narrow, (iv) V + A weak currents and a large anomaly in $\text{ν}$N reactions, (v) a possible heavy lepton.     

Quantum chromodynamics and charm photoproduction

It is shown that charm photoproduction can be consistently described within an asymptotically free field theory. Quantum chromodynamics is used to derive sum rules for the total cross section σ_c^γ which includes both production of mesons with hidden charm (J/ψ, ψ′ and so on) and of charmed particles (pairs $\text{D}\text{D}$, $\text{F}\text{F}$ and so on). An estimate of σ_c^γ as a function of energy is given and fast growth is discovered up to energies ～ 1000 GeV. In this energy range σ_c^γ turns out to be equal to several μb. It is argued that measurements of charm photoproduction would give the most direct information on the gluon distribution within a nucleon. All the results are generalized to production of heavier particles containing new quarks. In particular, a simple rescaling law is derived connecting the cross sections for charm and beauty.     

Effects of multiplicity on charm semileptonic decay distributions

We consider the effects of multiplicity in semileptonic decays of charmed D(1.87) mesons, produced near threshold in e⁺e^? collisions. We calculate the decay distributions from uncorrelated D → (nπ)Kev and resonance dominated $\text{D}\text{→}\text{K}{}^1\text{e}\text{v}$ modes. Recent data from DORIS suggest that modes with two or more final hadrons dominate strongly.     

Observation of pairs of charmed particles produced by high-energy photons in nuclear emulsions coupled with a magnetic spectrometer

Preliminary results of an experiment using nuclear emulsions exposed to a tagged photon beam at the CERN SPS (experiment WA58) are presented. Six events showing pairs of charmed particles have been found. One of these has been interpreted as an associated production of Λ_c⁺ and $\text{D}$⁰. The mean lifetime of the neutral D meson based on three events is τ⁰ = (0.58_?0.2^+0.8 × 10^?13 s,, whereas a statistical analysis of eight charged charmed particles, assumed to be D mesons, leads to an estimate of the mean lifetime of τ^± ≈ 4.4 × 10^?13 s.     

Remark on baryonic decays of B mesons

We point out that B mesons might possess significant baryonic decay modes like B → Λ_c$\text{N}$. Invoking a simple-minded spectator ansatz for B decays we estimate BR(B → Λ_c$\text{N}$+X) ≈ 2–13% while exclusive two-body channels might reach values of a few percent. Observation of such transitions could yield valuable information on the dynamics of weak decays and maybe even on charm baryons. The search for bottom baryons would, however, be made more difficult by a sizeable baryonic branching ratio of bottom mesons.     

Electromagnetic mass differences of the old and the charmed mesons

We predict for M_?⁺?M_?⁰ the values -3.4 ± 0.8 MeV using the ?-ω mixing and the quark model, respectively. The extracted parameters indicate the necessity of a relativistic treatment of the old mesons. The problem of extrapolating these parameters to the charmed mesons is discussed. Under conservative assumptions, we predict 1.7 ? M_D⁰ ? 2.2 MeV and .     

Charmed meson decays and right-handed currents

In the presence of right-handed currents including $\text{(}\text{c}\text{s}\text{)}{}_{\mathrm{<mtext>R</mtext>}}$, it is emphasized that the dominant parity-violating (-conserving) Hamiltonian for nonleptonic decays of charmed hadrons transforms like $\text{45}\text{+}\text{45}{}^1\text{(}\text{20″ +}\text{84}\text{)}$ of SU(4), and leads to distinctive results especially in D⁺ → K_Sπ⁺, F⁺ → μ⁺ν_μ and D⁰ → K^?e⁺ν_e, etc.     

A generalized VMD mechanism for radiative decays of cc mesons

A generalized VMD mechanism, implemented through the OPC model, is proposed for E1 and M1 decays of $\text{c}\text{c}$ mesons wherein the photon couples to two infinite sequences of radial excitations of ³S₁ and ³D₁$\text{c}\text{c}$ states. The results reveal good accord with data under the conventional assignments, with a parameter signifying a reduced magnetic coupling of ψ-ions with c quarks.     

Production of charmed particles at the CERN intersecting storage rings in events triggered by an electron

Production of charmed particles has been investigated at √s = 63 GeV usi ng the Lampshade Magnet detector triggered by electrons and positrons emitted at 30% from the ISR beam axis. The results of a search for Λ_c and $\text{Λ}$_c signals in the K^?pπ⁺ and K⁺$\text{p}$π^? channels are presented. Cross sections for the reactions pp → $\text{D}$Λ_cX and pp → Λ_c$\text{Λ}$_cX, and upper limits. for pp → D$\text{D}$X, are evaluated under various models and compared with other values obtained at the ISR.     

Semi-leptonic decays of charmed mesons produced in γN collisions

We report here on a study of the characteristics of the semileptonic decay spectra from a pair of charmed hadrons produced via photoproduction. The inclusive production of charmed hadrons is phenomenologically parametrized as e^?aze^?bp_t2. Their decays are described by (i) decay of free charm quark in GIM, (ii) K¹ dominant mode, $\text{D}\text{→}\text{K}{}^1\text{l}\text{ν}$, and (iii) pure leptonic decays. We deduce that 〈M_eμ²〉 = 0.18 M_D² for free quark decay and 〈M_eμ²〉 = ?0.35 +-0.24 M_D² for K¹ dominant decay. For the specific purpose of the photoproduction experiment at FNAL whicc is currently searching for μe events, we incorporate the incident photon spectrum, and the decay distributions with and without the experimental acceptance criteria are presented.     

B → F + X decay and pseudoscalar decay constants of explicitly flavored heavy mesons

If the current theoretical pictures of explicitly flavored heavy mesons are quantitatively correct, we expect that the branching ratio of B → $\text{F}$ + X (anything) may be 6 percent even in a conservative estimate. Accurate measurement of this branching ratio will determine the value of the pseudoscalar decay constant f_F, of the wave function at origin of the s wave $\text{c}$ s bound state in the potential picture, and help to clarify dynamical properties of heavy meson binding.     

Superfluidity of neutron matter: (II). Triplet pairing

The possibility of neutron triplet pairing and superfluidity in neutron star matter is investigated, and the energy gap and corresponding critical temperature is calculated or estimated as a function of Fermi momentum or density. The calculations are performed for a “one-pion-exchange gaussian” potential, and compared with the results for neutron and proton singlet pairing and superfluidity calculated earlier.The results indicate that neutron superfluidity, corresponding specifically to ³P₂ state pairing, may exist in a high-density shell in the nuclear-matter region of a neutron star, i.e. for 1.6 × 10¹⁴g/cm³ < ρ < 1.4 × 10¹⁵g/cm³, and the maximum self-consistent energy gap is Δ⁰₁k_F ≈ 0.6 MeV and Δ⁰₃(k_F) ≈ 0.1 MeV for an effective mass $\text{m}{}^1\text{≈ 0.75}\text{and}\text{k}{}_{\mathrm{<mtext>F</mtext>}}\text{≈ 2.1}\text{fm}{}^{\mathrm{?1}}$, i.e. for a mas ? ≈ 5.2 × 10¹⁴g/cm³. For $\text{m}{}^1\text{= 1.0}$ we get correspondingly Δ⁰₁(k_F) ≈ 3.3 MeV and Δ⁰₃(k_F) ≈ 0.6 MeV for k_F ≈ 2.2 fm^?1.     

Final state gluon effects in charmed meson decays

In the valence-quark c-decay scheme the decay $\text{D}{}^0\text{→}\text{K}{}^0\text{π}{}^0$ is expected to be strongly suppressed. We suggest that final state soft gluon exchange may account for the rather large branching ratio recently measured for this process, and study two-body decays of charmed mesons in our new scheme.     

Does the enhancement mechanism work in non-leptonic decays of heavy pseudoscalar mesons with new flavors (b and t)?

We show that the enhancement mechanism proposed for non-leptonic decays of charmed mesons (D⁰, F⁺) is still important for decays of pseudoscalar mesons with b flavor, while its effect is small for mesons with t flavor. For the semi-leptonic branching ratios of B^? (b$\text{u}$), B⁰(b$\text{d}$) and B_S⁰(b$\text{s}$) we predict BR (B^? → evX ～' 9%, BR(B⁰ → evX) ～' BR(B_s⁰ → evX) ～' 5%. We can also derive the enhancement of the branching ratios of uncharmed final states in B decays, i.e. $\text{BR}\text{(}\text{B}{}^{\mathrm{?}}\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext>}}\text{)}$ ～' 20 %, $\text{BR}\text{(}\text{B}{}^0\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>d</mtext>}}\text{)}$ ≈ 10%, where $\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext><mtext>(</mtext><mtext>s</mtext><mtext>d</mtext><mtext>)</mtext>}}$ = $\text{K}$π + ... + $\text{K}$K$\text{K}$ + ... .     

Two-body hadronic decays of the 3.1 GeV resonance

Hadronic two body decays of the 3.1 GeV resonance were measured and the following branching ratios were obtained: Γ_π⁺_π^?/Γ_μμ <0.0046, Γ_K⁺_K^?/Γ_μμ <0.0084, and $\text{Γ}{}_{\mathrm{p}}\text{p}\text{/ Γ}{}_{\mathrm{\mu }}{}_{\mathrm{\mu \mu }}\text{= 0.036 ± 0.010}$ assuming the p$\text{p}$ decay distribution is ≈ + cos²θ.     

Decoupling of higher vector mesons and charmed meson production in e+e− annihilation

The striking feature that $\text{D}$¹D¹ production is greatly enhanced at energies just above threshold is explained. We argue that higher excited vector mesons successively decouple from lower spin final states which manifests itself in an explicit decoupling scheme. This can be verified on quite general grounds. A quantitative analysis of charmed meson production near threshold is given. Further evidence of the decoupling scheme coming from old data is discussed.     

Unitarity constraints on radiative ϒ decays and possible interpretations of ζ(8.32)

If ζ is a scalar or pseudoscalar meson whose decay rate of less than 80 MeV is given by two gluon decays, the decay ? → γ + ζ with its branching ratio of ≈5 × 10^?3 cannot be mediated by gluonic interaction between ζ and the ?, if perturbative QCD is applicable to this reaction and if absorptive and dispersive parts are of comparable magnitude. Similar, though less stringent arguments apply for tensor mesons and no conflict arises for axial vector states. If ζ is a gluino ball and if b? is lighter than expected on theoretical grounds, the predicted rate is compatible with experiment. The experimental limit $\text{Br(? ′ → γ + ζ)}\text{Br(? → γ + ζ)}\text{< 0.22}$ cannot be accomodated within this framework.     

Measurement of the total cross-section difference for pp scattering in longitudinal spin states

Theoretical arguments more general than original MIT bag calculation predict exotic charmed-strange scalar mesons with striking signatures in same mass range as F and F¹, on the same basis as the prediction of the low-lying nonexotic qq$\text{qq}$ scalar nonet. Identification of δ (970) as qq$\text{qq}$ state enables rough mass prediction for charmed-strange exotics via charmed-strange analogy. Dominant signatures and decay modes of exotics are discussed.