Using the QCD sum rules we test if the charmonium-like structure Y(4274), observed in the $J/ψϕ$ invariant mass spectrum, can be described with a $D_s\bar{D}_{s0}(2317)+h.c.$ molecular current with $J^{PC}=0^{-+}$. We consider the contributions of condensates up to dimension ten and we work at leading order in $α_s$. We keep terms which are linear in the strange quark mass $m_s$. The mass obtained for such state is $m_{D_s{D}_{s0}}=(4.80\pm 0.55)$ GeV. We also consider a molecular $0^{-+}$ $D\bar{D}_{0}(2400)+h.c.$ current and we obtain $m_{D{D}_0}=(4.61\pm 0.71)$ GeV. Our study shows that the newly observed Y(4274) in the $J/ψϕ$ invariant mass spectra can be, considering the uncertainties, described using a molecular charmonium current.
The recent data for E866 experiment on the x_F dependence for charmonium suppression in pA collisions at 800 GeV are analyzed using a time- and energy-dependent preformed charmonium absorption cross section σ_{abs}^ψ(τ,\sqrt{s}). For \sqrt{s}=10 GeV the initially (τ=0) produced premeson has an absorption cross section of σ_{pr}~3mb. At the same energy but for τ-> \infty one deduces for the total cross sections σ_{tot}^{J/Psi N}=(2.8\pm 0.3)mb, σ_{tot}^{J/Psi N}= (10.5\pm 3.6)mb. The date are compatible with a formation time τ_{1/2}=0.6 fm/c.
e+e- Experiments producing charmonium are reviewed. It is found that the contribution of the continuum amplitude via virtual photon was neglected in almost all the experiments and the channels analyzed. It is shown that the contribution of the continuum part may affect the final results significantly in psi(2S) and psi(3770) decays, while the interference between continuum and resonance amplitudes may even affect the J/psi decays as well as the psi(2S) and psi(3770). This should be considered in analyzing the "rho-pi puzzle" between J/psi and psi(2s) decays, and the difference between inclusiv…
A new explanation for the longstanding puzzle of the tiny branching fraction of psi' --> rho pi relative to that for J/psi --> rho pi was proposed. In the case of J/psi, we argue that this decay is dominated by a higher Fock state in which the c cbar pair is in a color-octet ^3S_1 state and annihilates via the process c cbar --> q qbar. In the case of the psi', we argue that the probability for the c cbar c pair in this higher Fock state to be close enough to annihilate is suppressed by a dynamical effect related to the small energy gap between the mass of the psi' and the D Dbar threshold.
Elastic virtual photoproduction cross sections gamma^*p -> J/psi(psi')p and total charmonium-nucleon cross sections for J/psi, psi' and chi states are calculated in a parameter free way with the light-cone dipole formalism and the same input: factorization in impact parameters, light-cone wave functions for the gamma^* and the charmonia, and the universal phenomenological dipole cross section which is fitted to other data. The charmonium wave functions are calculated with four known realistic potentials, and two models for the dipole cross section are tested. Very good agreement with data for …
Hadrons produced in high-energy heavy-ion collisions can suppress the production of J/psi and other charmonium states by charmonium spontaneous dissociation as the hot hadronic environment alters the interaction between the charm quark and charm antiquark. Furthermore, hadrons can thermalize a charmonium to excite it to higher charmonium states which subsequently dissociate spontaneously. They can also collide with a charmonium to lead to its prompt dissociation into an open charm pair.
In this paper we consider a sequential "meson emission" mechanism for charmonium decays of the type Psi -> N Nbar m, where Psi is a generic charmonium state, N is a nucleon and m is a light meson. This decay mechanism, which may not be dominant in general, assumes that an NNbar pair is created during charmonium annihilation, and the light meson m is emitted from the outgoing nucleon or antinucleon line. A straightforward generalization of this model can incorporate intermediate N* resonances. We derive Dalitz plot event densities for the cases Psi = eta_c, J/psi, chi_c0, chi_c1} and psi' and m…
Using information on B-meson fragmentation functions from CERN LEP 1 and adopting the nonrelativistic QCD factorization formalism proposed by Bodwin, Braaten, and Lepage, we predict the transverse-momentum distribution of J/psi mesons originating from the inclusive decays of b hadrons produced in p p-bar collisions at the Fermilab Tevatron. We determine the relevant colour-octet charmonium matrix elements from fits to CDF data on prompt charmonium hadroproduction and to CLEO data on charmonium production from B-meson decay. Our predictions are found to agree well with recent CDF and D0 data.
Charmonium production and suppression in In+In and Pb+Pb reactions at SPS energies is investigated with the HSD transport approach within the 'hadronic comover model' as well as the 'QGP threshold scenario'. The results of the transport calculations for J/Psi suppression and the Psi prime to J/Psi ratio are compared with the recent data of the NA50 and NA60 Collaborations. We find that the comover absorption model - with a single parameter |M_0|^2 for the matrix element squared for charmonium-meson dissociation - performs best with respect to all data sets. The 'threshold scenario' - within di…
We suggest the ratio of the $ψ''(3770)/ψ'(3686)$ production cross sections as an unambiguous probe of the dominance of hard, point-like physics in charmonium production. If hard physics dominates the charmonium production the ratio : ${σ(ψ'')\overσ(ψ')}\approx {Γ(ψ''\to l^+l^-)\over Γ(ψ'\to l^+l^-)} \approx 0.1$ is independent of the process. We argue that since the dominant $D\bar D$ decay mode of the $ψ''$-meson can be detected with a high efficiency at the current facilities the effective counting rate for the $ψ''$ production should be comparable to that of the $ψ'$ and hence it could be o…
The recent measurements by CLEO Collaboration for the inclusive J/Psi and Psi(2S) production in Upsilon(1S) decay and our previous calculation are analyzed. The J/Psi momentum spectrum and the production ratio of Psi(2S) versus J/Psi favour Upsilon to J/Psi(Psi(2S)) + ccbar g as the dominant contribution. We point out that the differences between the experimental data and our previous results are mainly originated from the setting of the parameter charm quark mass. We further suggest the associate strange particle enhancement as a probe for the open charm particles in Upsilon to J/Psi (Psi(2S)…
Finite temperature lattice QCD indicates that the charmonium ground state J/psi can survive in a quark-gluon plasma up to 1.5 T_c or more, while the excited states chi_c and psi-prime are dissociated just above T_c. We assume that the chi_c suffers the same form of suppression as that observed for the psi-prime in SPS experiments, and that the directly produced J/psi is unaffected at presently available energy densities. This provides a parameter-free description of J/psi and psi-prime suppression which agrees quite well with that observed in SPS and RHIC data.
The role of power corrections and higher Fock-state contributions to exclusive charmonium decays will be discussed. It will be argued that the J/Psi (Psi') decays into baryon-antibaryon pairs are dominated by the valence Fock-state contributions. P-wave charmonium decays, on the other hand, receive strong contributions from the c cbar g Fock states since the valence Fock-state contributions are suppressed in these reactions. Numerical results for J/Psi (Psi') --> B Bbar decay widths will be also presented and compared to data.
Meson-charmonium dissociation reactions governed by the quark interchange are studied with temperature-dependent quark potentials. Quark-antiquark relative-motion wave functions and masses of charmonia and charmed mesons are determined by the central spin-independent part of the potentials or by the central spin-independent part and a smeared spin-spin interaction. The prominent temperature dependence of the masses is found. Based on the potentials, the wave functions, and the meson masses, we obtain temperature-dependent cross sections for fifteen pion-charmonium and rho-charmonium dissociati…
Prompt gluons are an additional source for charmonium suppression in nuclear collisions, in particular for nucleus-nucleus collisions. These gluons are radiated as bremsstrahlung in N-N collisions and interact inelastically with the charmonium states while the nuclei still overlap. The spectra and mean number <n_g> of the prompt gluons are calculated perturbatively and the gluon-Psi inelastic cross section is estimated. The integrated cross sections for AB --> J/Psi (Psi')X for p-A and A-B collisions and the dependence on transverse energy for S-U and Pb-Pb can be described quantitatively with…
A collision of a light meson and a charmonium produces quarks and antiquarks first, then the charm quark fragments into a charmed hadron, and finally three or more mesons are produced. This is the mechanism that we consider and propose to understand the prompt-J/psi nuclear modification factor in the range of J/psi transverse momentum from 10 GeV/c to 18 GeV/c, as measured by the CMS Collaboration and the ATLAS Collaboration. Unpolarized cross sections are derived and calculated for the reactions pion+charmonium ->H_c+X with H_c being a charmed meson. Numerical cross sections are parametrized …
The role of higher Fock-state contributions to exclusive charmonium decays will be discussed. It will be argued that the J/Psi (Psi') decays into baryon-antibaryon pairs are dominated by the valence Fock-state contributions. P-wave charmonium decays, on the other hand, receive strong contributions from the c cbar g Fock states since the valence Fock-state contributions are suppressed in these reactions. Numerical results for the decay widths of J/Psi (Psi') into baryon-antibaryon and chi(J) into pairs of pseudoscalar mesons will be also presented and compared to data.
The ratio of branching fractions Br(X(3872) --> gamma J/psi)/ Br(X(3872) --> pi^+ pi^- J/psi) is studied by assuming that the X(3872) --> pi^+ pi^- J/psi decay proceeds through the rho^0 meson pole which is caused by the omega-rho^0 mixing. As the result, it is seen that the calculated ratio is compatible with the measured values of the ratio when X(3872) is an axial-vector tetra-quark state, while it would be much larger than the measurements when it is a charmonium. Therefore, the existing data on the ratio seem to favor the tetra-quark interpretation of X(3872) over the charmonium, although…
We compute the O(alpha_s^2) correction to the decay rate eta_c --> gamma gamma and discuss its implications for precision quarkonium physics. We study the suitability of the ratio Gamma(J/psi --> e+e-)/Gamma(eta_c --> gamma gamma), in which the non-perturbative or soft effects cancel at O(alpha_s^{0,1}), for extracting fundamental parameters of QCD at low energies. We show that the QCD-based theory of charmonia is not capable of predicting this ratio with any degree of confidence.
We discuss the theoretical status of inclusive radiative decays of charmonium, with a particular emphasis on the QCD description of the photon spectrum, where progress has occurred in recent years. We also comment on the possible extraction of alpha_s (M_J/psi) and on the possibility to gain important information on the nature of J/psi and psi (2S).
Data from J/psi and psi' production in p-A collisions are used to determine the cross section for absorption of pre-resonance charmonium in nuclear matter. The J/psi suppression in O-Cu, O-U and S-U collisions is fully reproduced by the corresponding nuclear absorption, while Pb-Pb collisions show an additional suppression increasing with centrality. We study the onset of this change in terms of hadronic comover interactions and conclude that so far no conventional hadronic description can consistently account for all data. Deconfinement, starting at a critical point determined by central S-U …
In this invited talk I discuss two recent applications of charmonium (Psi) decays to N Nbar m final states, where N is a nucleon and m is a light meson. There are several motivations for studying these decays: 1) They are useful for the study of N* spectroscopy; 2) they can be used to estimate cross sections for the associated charmonium production processes p pbar to Psi m, which PANDA plans to exploit in searches for charmonium hybrid exotics; and 3) they may allow the direct experimental measurement of NNm (meson-nucleon) strong couplings, which provide crucial input information for meson e…
Study of CP violation in the decay channel Bs->J/psi phi is essential to exploring and constraining physics beyond the Standard Model in the quark flavour sector. The experimental progress in this area of activity at the LHC and Tevatron is discussed.
Approximately taking into account the higher-order effects due to multiple-gluon initial-state radiation, we extract from the latest Tevatron data of prompt J/psi hadroproduction the leading colour-octet matrix elements within the nonrelativistic-QCD (NRQCD) factorization formalism proposed by Bodwin, Braaten, and Lepage. We find that the matrix elements which describe the formation of J/psi mesons from colour-octet cc-bar pairs in the angular-momentum states ^{2S+1}L_J = ^1S_0 and ^3P_J, with J = 0,1,2, which are responsible for the excess of the predicted cross section of inelastic J/psi pho…
We study the charmonium suppression in different evolutions of quark gluon plasma (QGP) based on the transport model. In the colliding energies of Large Hadron Collider, charmonium final yields are dominated by the recombination of charm and anti-charm quarks in the deconfined phase. Heavy quark diffusions depend less on the shear viscosity of the bulk medium, which makes the J/psi nuclear modification factor in the entire pT bin shows weak dependence on the shear viscosity of QGP. However, charmonium with high transverse momentum pT, can only be produced in the early stage of nuclear collisio…
A kinetic equation approach is applied to model anomalous J/psi suppression at RHIC and SPS by absorption in a hadron resonance gas which successfully describes statistical hadron production in both experiments. The puzzling rapidity dependence of the PHENIX data is reproduced as a geometric effect due to a longer absorption path for J/psi production at forward rapidity.
The interpretation of the J/psi suppression patterns observed in nuclear collisions, at CERN and RHIC, as a signature of the formation of a deconfined phase of QCD matter, requires knowing which fractions of the measured J/psi yields, in pp collisions, are due to decays of heavier charmonium states. From a detailed analysis of the available mid-rapidity charmonium hadro-production cross sections, or their ratios, we determine that the J/psi feed-down contributions from psi' and chi_c decays are, respectively, (8.1 +/- 0.3) % and (25 +/- 5) %. These proton-proton values are derived from global …
We study the J/Psi production from nuclei near the kinematic threshold within the collision model, based on the nuclear spectral function, for incoherent primary proton-nucleon charmonium creation processes. The model takes into account the initial proton and final J/Psi absorption, target nucleon binding and Fermi motion, the formation length of J/Psi mesons as well as the effect of their nuclear mean-field potential on these processes. We calculate the A dependences of the absolute and relative (transparency ratio) charmonium yields as well as its excitation function within the different sce…
CERN collaboration NA50 has measured charmonium and Drell-Yan dimuon production in Pb+Pb collisions. Parton scattering broadens the transverse momentum, p_T, distributions for these processes. We predict that the average p_T^{2} will flatten in Pb+Pb collisions as a function of the neutral transverse energy of hadrons, E_T, in contrast to the almost-linear rise seen in S+U - psi +X. If seen, such a flattening will support hadronic explanations of charmonium suppression. Figures 2 and 5 are improved and numerous typographical errors are corrected.
The QCD mechanisms underlying the exclusive strong decays and hadronic production amplitudes of charmonium remain poorly understood, despite decades of study and an increasingly detaled body of experimental information. One set of hadronic channels of special interest are those that include baryon-antibaryon states. These are being investigated experimentally at BES and CLEO-c in terms of their baryon resonance content, and are also of interest for the future PANDA experiment, in which charmonium and charmonium hybrids will be produced in p-pbar annihilation in association with light mesons. I…
We argue that the X(4260) enhancement contains a wealth of information on vector c-cbar spectroscopy. We discuss the shape of the X(4260) observed in the OZI-forbidden process "electron-positron into J/psi and a pair of charged pions", in particular at and near vector charmonium resonances as well as open-charm threshold enhancements. The resulting very broad X(4260) structure does not seem to classify itself as a vector charmonium resonance, but its detailed shape allows to identify new vector c-cbar states. Here, we estimate the resonance parameters of the psi(3D) state.
The production of charmonia in heavy-ion collisions is investigated within a kinetic theory framework simultaneously accounting for dissociation and regeneration processes in both quark-gluon plasma (QGP) and hadron-gas phases of the reaction. In-medium modifications of open-charm states (c-quarks, D-mesons) and the survival of J/psi mesons in the QGP are included as inferred from lattice QCD. Pertinent consequences on equilibrium charmonium abundances are evaluated and found to be especially relevant to explain the measured centrality dependence of the psi'/psi ratio at SPS. Predictions for r…
The cross sections for the charmonium production processes p pbar -> m Psi, where m is a light meson and Psi is a charmonium state, are of great interest for the planned p-pbar experiment PANDA. In this paper we estimate these cross sections using known results for the decays Psi -> m p pbar which are related to these reactions by crossing. In lieu of detailed experimental data on the decay Dalitz plots, we assume a constant amplitude as a first approximation; this implies a simple relation between the cross sections and decay widths. The single measured exclusive cross section of this type is…
We study the scattering lengths of charmonia (J/psi and eta_c) with light hadrons (pi, rho and N) by the quenched lattice QCD simulations on 24x24x24x48, 32x32x32x48 and 48x48x48x48 lattices with the lattice spacing a = 0.068 fm. The scattering length is extracted by using the Luscher's phase-shift formula together with the measurement of the energy shift Delta E of two hadrons on the lattice. We find that there exist attractive interactions in all channels, J/psi(eta_c)-pi, J/psi(eta_c)-rho and J/psi(eta_c)-N: The s-wave J/psi-pi (eta_c-pi) scattering length is determined as 0.0119+-0.0039 fm…
We study the properties of charmonium in a strongly coupled QCD-like plasma at finite momentum. As a basis for this study, a "bottom-up" holographic model is used which has been previously shown to reproduce charmonium phenomenology in vacuum and give a reasonable dissociation temperature at zero momentum. The finite momentum spectral functions are presented and found to be consistent with recent lattice results. The in-medium dispersion relation and momentum dependence of decay width of J/Psi have also been studied. We find no signature of a subluminal limiting velocity from the dispersion re…
We evaluate the Psi' to J/Psi ratio in diffractive photoproduction in a light-cone framework, using charmonium wave functions extracted from non-relativistic potential models. Contrary to current belief, we find that the best estimate for the ratio is a factor 2 to 5 below the data. The measured ratio constrains the distribution of the charm quark-antiquark component of the charmonium light-cone wave function and indicates that it is more compact than in potential models. We predict that the inelastic photoproduction ratio will be bigger than the elastic one, and will equal that measured in ha…
We use the framework of a relativistic constituent quark model to study the semileptonic transitions of the Bc meson into CCbar charmonium states where CCbar = etaC (1S0), J/psi (3S1), chiC0 (3P0), chiC1 (3P1), hc (1P1), chiC2 (3P2), psi (3D2). We compute the q^2-dependence of all relevant form factors and give predictions for their semileptonic Bc decay modes including also their tau-modes. We derive a formula for the polar angle distribution of the charged lepton in the (l nu) c.m. frame and compute the partial helicity rates that multiply the angular factors in the decay distribution. For t…
The cross section for the photoproduction of large-p_T J/psi mesons at HERA is calculated at next-to-leading order, adopting a perturbative approach to describe the fragmentation of charm quarks and gluons into J/psi mesons. We treat the charm quark according to the massless factorization scheme, where it is assumed to be one of the active flavours inside the proton and the resolved photon. We present inclusive distributions in transverse momentum and rapidity, including the contributions due to direct and resolved photons. The importance of the colour-octet components of the J/psi wave functi…
In e^+e^- annihilation at \sqrt{s}=10.6 GeV Belle Collaboration found, that J/psi mesons are predominantly produced in association with an extra \bar{c}c pair. The possible mechanisms of J/psi production are discussed and the probability of the associate production of \bar{c}c pair is estimated. The choice between these mechanisms can be done by measuring J/psi polarization. It is suggested, that in case of heavy ion collisions one may expect remarkable transverse polarization of produced J/psi, if quark-gluon plasma if formed. The measurement of asymmetry of e^+e^-(μ^+μ^-) angular distributio…
The theoretical explanations about the ``Rho-pi puzzle'' in charmonium decays are reviewed extensively, and the comparison of theoretical predications with experimental data is made whenever possible. Three methods to estimate the ratio of the branching fractions of J/psi and psi' decays are also discussed. It is pointed out that in order to understand the Rho-pi puzzle, and the dynamics of charmonium decays, systematic studies should be made in theory, phenomenology and experiment aspects.
Within a perturbative approach we investigate decays of charmonium states into baryon-antibaryon pairs. Using a recently proposed wave function for the nucleon and suitable generalizations of it to the hyperons and decouplet baryons, we obtain the decay widths for the baryon-antibaryon channels in reasonable agreement with data. An important difference to previous work is the use of the c-quark mass in the perturbative calculation instead of the charmonium mass. As a consequence of this feature our approach possesses, the J/Psi and the Psi' decay widths do not scale with a high power of the ra…
We investigate the pattern of asymmetries in the colour-octet model for inclusive production of charmonium with polarised initial state hadrons and photons. We find that singly polarised asymmetries vanish. The double polarised asymmetry for J/psi involves a new combination of long-distance matrix element. We also investigate the asymmetries for eta_c, chi_c and Upsilon production. The asymmetries distinguish well between different models of charmonium production.
Models with essential non-perturbative QCD dynamics for the production of charmonium are extrapolated to give predictions of prompt J/psi production at the LHC. Differences of up to an order of magnitude occurs, although the different models all describe the Tevatron data on high-pT charmonium. An important point is here the treatment of higher order perturbative QCD effects. We also discuss the large rate of prompt J/psi from these models as a background to CP violation studies.
We extract the pole positions, hadronic and gamma-gamma widths of sigma and f_0(980, from pi-pi and gamma-gamma scattering data using an improved analytic K-matrix model. Our results favour a large gluon component for the sigma and a \bar ss or/and gluon component for the f_0(980) but neither a large four-quark nor a molecule component. Gluonium sigma_B production from J/psi, phi radiative and D_s semi-leptonic decays are also discussed.
Recently, the CDF and D0 collaborations measured indirect CP violation in Bs -> J/psi phi and found a hint of a signal. If taken at face value, this can be interpreted as a nonzero phase of Bs-Bsbar mixing (beta_s), in disagreement with the standard model, which predicts that beta_s ~= 0. In this paper, we argue that this analysis may be incomplete. In particular, there can be new physics (NP) in the bbar -> sbar c cbar decay. If so, the value of beta_s is different than for the case in which NP is assumed to be present only in the mixing. We have examined several models of NP and found that, …
We investigate the in-medium modification of pseudoscalar and vector mesons in a QCD motivated chiral quark model by solving the Dyson-Schwinger equations for quarks and mesons at finite temperature for a wide mass range of meson masses, from light (pi, rho) to open-charm (D, D*) states. At the chiral / deconfinement phase transition, the quark-antiquark bound states enter the continuum of unbound states and become broad resonances (the hadronic Mott effect). We calculate the in-medium cross sections for charmonium dissociation due to collisions with light hadrons in a chiral Lagrangian approa…
This paper is concerned with the physics of meson decays to J/psi and phi.These decays have been observed at the Tevatron [7] and, in particular, should be copiously observed at the LHCb detector. This paper gives a concise presentation of the basic physics analysis and a general formalism for analyzing the signals of CP violation.
The production of charmonia in relativistic heavy-ion collisions is formulated within the framework of a quantum kinetic theory simultaneously accounting for breakup and recombination processes. The survival probability of J/Psi mesons is evaluated for a Mott-Hagedorn resonance gas, whereby the pattern of anomalous J/Psi suppression at CERN-SPS can be explained by a strong coupling to open-charm states and their in-medium modification. Recent data for charmonium suppression from Au-Au collisions at RHIC are discussed.
The narrow charmonium state near 3872 MeV reported by the Belle collaboration and confirmedby CDF lies almost exactly at the neutral D anti-D* threshold. As was predicted many years ago it can be a deuteronlike meson-meson state called a deuson. If so, it should be an axial, or possibily a pseudoscalar state with C=0, and isospin predominantly 0. Large isospin breaking is expected because of the isospin mass splitting between the neutral and charged D (D*) mesons. Because of this large isospin breaking the decay X(3872) to J/psi rho would be allowed, while J/psi sigma would be forbidden by C-p…
We calculate the exclusive cross sections for e^+ e^- annihilation into two charmonium states through a virtual photon. Purely electromagnetic contributions are surprisingly large, changing the cross sections by as much as 21%. The predicted cross section for J/psi + eta_c is about an order of magnitude smaller than a recent measurement by the BELLE Collaboration, although part of the discrepancy can be attributed to large relativistic corrections. The cross sections for S-wave + P-wave, P-wave + P-wave, and S-wave + D-wave charmonium states are also calculated. It may be possible to discover …
We analyze B -> K H_c (where H_c = eta_c, J/psi, chi_{cJ(J=0,1)}) decays estimating nonfactorizable contributions from the light-cone sum rules (LCSR). Nonfactorizable contributions are sizable for B -> K J/psi and particularly for B -> K chi_{c1} decay. For the B decays into a (pseudo)scalar charmonia we find small nonfactorizable contributions which cannot accommodate relatively large branching ratios obtained by measurements. This specially concerns the puzzling B -> K chi_{c0} decay.
We emphasize that the recent measurements of the B^0_s - bar B^0_s mass difference Delta M_s by the CDF and D0 collaborations offer an important model independent test of minimal flavour violation (MFV). The improved measurements of the angle gamma in the unitarity triangle and of |V_ub| from tree level decays, combined with future accurate measurements of Delta M_s, S_{psi K_S}, S_{psi phi}, Br(B_{d,s} -> mu+ mu-), Br(B -> X_{d,s} nu bar nu), Br(K+ -> pi+ nu bar nu) and Br(K_L -> pi^0 nu bar nu) and improved values of the relevant non-perturbative parameters, will allow to test the MFV hypoth…
The newly reported Y(4260) becomes the second most massive state in the charmonium family. We argue that it displaces the psi(4415) as the (largely) 4s vector charmonium state, recall s-d wave interference to explain the lack of a signal in e-e+ to hadrons and suggest some further study avenues that can exclude exotic meson assignments. The absence of a J/psi KK mode can be understood, beyond phase space suppression, to be a consequence of chiral symmetry. We also provide a model calculation in this sector showing that, although forcing the fit somewhat (which suggests a small sea quark wavefu…
Data on B+ --> J/psi phi K+ and the Y(4140) enhancement recently reported by the CDF collaboration [arxiv:0903.2229] are analysed. The threshold behaviour, as well as traces of the X(4260) enhancement, the known c-cbar resonances psi(2D), psi(4S), and a tentative psi(3D) state, as observed in the mass distribution, suggest that the J/psi+phi system has quantum numbers JPC=1--. It is then argued that the Y(4140) enhancement does not represent any kind of resonance, but instead is a natural consequence of the opening of the J/psi+phi channel.
We discuss features of charmonium suppression at $\sqtr{s} = 200$ GeV within the framework of the Glauber-Gribov theory and the comovers interaction model. The latter approach has been extended by allowing for secondary charmonium production due to recombination of $c\bar{c}$ pairs in the medium, estimated from pp data at the same bombarding energy. Centrality and rapidity dependence of the nuclear modification factor for J/psi in d+Au, Cu+Cu and Au+Au collisions at RHIC are reproduced without fitting a single model parameter. A strong suppression of J/psi is predicted for LHC energies.
We present an analysis of the existing data on charmonium hadro-production based on non-relativistic QCD (NRQCD) calculations at the next-to-leading order (NLO). All the data on J/psi and psi' production in fixed-target experiments and on pp collisions at low energy are included. We find that the amount of color octet contribution needed to describe the data is about 1/10 of that found at the Tevatron.
The charmonium dissociation by mesons in relativistic heavy-ion reactions is analyzed within the Regge approach. It is shown that the inclusion of the initial and final state interactions in the dissociation of J/Psi to bar{D}* D* close to threshold increases the cross section significantly and can not be neglected in comparison to the total dissociation rate. This is due to resonant bar{D}*-D* interactions in sqrt{s} close to the masses of the Psi(4.04) and Psi(4.16) mesons. We also investigate thermal effects of the (c bar{c}) width for such processes in the medium. All these effects change …
The a0(980)-f0(980) mixing intensity has been predicted to be in the range of 0.01 to 0.1 by various theoretical models, but lacking firm experimental observation. We examine the possibility of extracting the a0(980)-f0(980) mixing from J/psi -> phi f0 -> phi a0 reaction at upgraded Beijing Electron Positron Collider with BESIII detector. While the branching ratio of this process through the a0(980)-f0(980) mixing is expected to be about $O(10^{-6})$ similar to the estimated total amount from two background reactions J/psi -> gamma* -> phi a0 and J/psi -> K* K + c.c. -> phi a0, the peak width …
We calculate the contributions from QED processes involving two virtual photons to the cross sections for e^+ e^- annihilation into two charmonium states with the same C-parity. Generically, the cross sections are three orders of magnitude smaller than those for charmonia with opposite C-parity because they are suppressed by a factor of alpha^2/alpha_s^2. However, if both charmonia have quantum numbers J^{PC} = 1^{--}, then there is a contribution to the cross section that involves the fragmentation of each photon into a charmonium. The fragmentation contribution is enhanced by powers of E_{be…
