Search

The GlueX facility, featuring a linearly polarized 9 GeV real photon beam delivered to a large-acceptance detector system, has recently completed its first phase of running, and analysis efforts of this dataset are well underway. It has been suggested that at GlueX energies, quark systems beyond the three quark and quark-antiquark systems of baryons and mesons, such as hybrid mesons, tetraquarks and glueballs, should exist, and studies of these systems could shed new light on how quarks combine under the strong force, particularly the role played by gluons. GlueX data encompasses final states at energies where photoproduction of light scalar mesons, such as a0(980) and f0(980), can provide discriminatory evidence between various models, manifested in experimental observables such as the cross section and beam asymmetry, however many of these analyses comprise multi-particle final states, which can arise from numerous intermediate resonances formed via different production mechanisms. The work presented showcases efforts to measure the beam asymmetry of the reaction γp → pηπ, with a particular interest in future studies of the a0(980) meson, and discusses the application of longitudinal phase space plots, originally introduced by van Hove fifty years ago, as a means of optimizing event selection. This technique has found traction in several multi-particle final state analyses in GlueX, and provides an effective additional means of separately visualising meson and baryon production events with the same final state. [ABSTRACT FROM AUTHOR]

The goal of these proceedings is to review recent progress in studies of mesons with (hidden or open) charm or strangeness in nuclear matter. Particular focus is laid on the ϕ and D mesons which are particularly interesting in view of studying the effect of the partial restoration of chiral symmetry at finite density. Both effective theory approaches based on hadronic degrees of freedom and QCD methods involving quarks and gluons will be discussed. [ABSTRACT FROM AUTHOR]

The Nambu–Jona-Lasinio quark model is a successful tool for investigating hadron physics and the spontaneous chiralsymmetry-breaking mechanism. In this paper its generalization for SU(2) isospin group is presented. It includes all possible quantum numbers of spin-1 mesons. Simultaneous consideration of all these states leads to interesting predictions like novel mass formula and relations among meson coupling constants. [ABSTRACT FROM AUTHOR]

The simplest form of the Hyperfine Interaction (HFI) of quarks is a color-spin interaction, sometimes called Fermi-Breit (FB) HFI. For conventional hadrons, this HFI for quark-antiquark (qq̄) pairs is twice as strong as the same HFI for quark-quark (qq or q̄q̄) pairs, but this difference is absorbed into the different HFI constants for mesons and baryons, which are free parameters of the fits. For tetraquarks, however, qq̄ HFI is only half as strong as the qq/q̄q̄ HFI and both kinds of pairs coexist within the same state. Hence it is worth investigating a model with different fit constants for qq̄ and qq/q̄q̄ pairs. We have investigated 3 models of spin-color HFI for light scalar tetraquarks: 2 models with single constants for both kinds of pairs and one model with different fit constants. The light scalar nonet is chosen because of a lack of other experimentally observed multiplets interpretable as pure exotic states. Since even the nonet contains only 3 particles with distinct masses (i. e. 3 fit points), the constituent quark masses had to be taken from conventional hadron fits obtained in our previous work. The two-constant model did not prove to be a viable alternative to the one-constant models. [ABSTRACT FROM AUTHOR]

We give a snapshot of recent progress in solving the Dyson-Schwinger equation with a beyond rainbow-ladder ansatz for the dressed quark-gluon vertex which includes ghost contributions. We discuss the motivations for this approach with regard to heavy-flavored bound states and form factors and briefly describe future steps to be taken. [ABSTRACT FROM AUTHOR]

The flavour-changing quark-Higgs coupling does not arise at the tree level in the Standard Model. It is, however, induced by one-loop effects. In this paper, we present an exact calculation of the Higgs-penguin vertex in the 'tHooft-Feynman gauge. Renormalization of the vertex is effected by a prescription by Chia and Chong which gives an expression for the counter term identical to that obtained by employing Ward-Takahashi identity. The on-shell vertex function for the Higgs-penguin vertex is obtained, and its dependence on Higgs mass is investigated. Our calculation is applied to the following process: decays of Higgs boson into pseudoscalar meson pair of different flavours: Kπ and BK. The coupling of pseudoscalar meson to quark is effected through γ5 coupling. The decay rates are found to be very small. [ABSTRACT FROM AUTHOR]

Recent and planned measurements of exclusive meson production at COMPASS are discussed. In particular, results on transverse target spin asymmetry Asin([lowercase_phi_synonym]-[lowercase_phi_synonym]S)UT for exclusive ρ0 production are presented. This asymmetry is sensitive on the 'elusive' GPDs E, which are related to the orbital angular momentum of quarks. First observation of exclusive π0 meson production at COMPASS is also reported. [ABSTRACT FROM AUTHOR]

In the first half-century of cosmic ray physics, the primary research focus was on elementary particles; the positron, pi-mesons, mu-mesons, and hyperons were discovered in cosmic rays. Much of this research was carried out at mountain elevations; Pic du Midi in the Pyrenees, Mt. Chacaltaya in Bolivia, and Mt. Evans/Echo Lake in Colorado, among other sites. In the 1960s, claims of the observation of free quarks, and satellite measurements of a significant rise in p-p cross sections, plus the delay in initiating accelerator construction programs for energies above 100 GeV, motivated the Michigan-Wisconsin group to undertake a serious cosmic ray program at Echo Lake. Subsequently, with the succession of higher energy accelerators and colliders at CERN and Fermilab, cosmic ray research has increasingly focused on cosmology and astrophysics, although some groups continue to study cosmic ray particle interactions in emulsion chambers. [ABSTRACT FROM AUTHOR]

The diquark is a system of two strongly correlated quarks. Obviously no free diquarks can exist, since they carry color. However they can theoretically form inside hadrons. While the actual possibility that two quarks can form stable bounds inside hadrons is still discussed, the use of a diquark effective degree of freedom can be very useful because it reduces the total number of states predicted and simplify the interactions inside hadrons. Here we present a possible application of the diquark to the tetraquark meson in the diquark-antidiquark limit. In this limit the tetraquark meson is composed of a diquark and an antidiquark. The complete set of states are constructed and a simple algebraic mass formula is applied in order to calculate the spectrum. [ABSTRACT FROM AUTHOR]

The first challenge faced in investigating the strong interaction from partially explored, where meson-cloud degrees of freedom dominate, to still unexplored distance scales, where the dressed-quark contributions are the dominating degrees of freedom, is to find an experiment that allows to measure observables that are probing this evolving nonperturbative QCD regime over the full range. Baryon spectroscopy can establish more sensitively, and in an almost modelindependent way, nucleon excitation and non-resonant reaction amplitudes by complete measurements of pseudo-scalar meson photoproduction off nucleons. Elastic and transition form factors can then trace this evolution by measurements of elastic electron scattering and exclusive singlemeson and double-pion electroproduction cross sections off the nucleon that will be extended to higher momentum transfers with the energy-upgraded CEBAF beam at JLab to study the dressed quark degrees of freedom, where their strong interaction is responsible for the ground and excited nucleon state formations. After establishing unprecedented high-precision data, the immanent next challenge is a high-quality analysis to extract these relevant electrocoupling parameters for various resonances that then can be compared to state of the art models and QCD-based calculations. Recent results demonstrate the status of the analysis and pinpoint further challenges, including those to establish QCD-based results directly from the experimental data. [ABSTRACT FROM AUTHOR]

A Dyson-Schwinger equation calculation of the light hadron spectrum, which correlates the masses of meson and baryon ground- and excited-states within a single framework, produces a description of the Roper resonance that corresponds closely with conclusions drawn recently by EBAC. Namely, the Roper is a particular type of radial excitation of the nucleon's dressed-quark core augmented by a material meson cloud component. There are, in addition, some surprises. [ABSTRACT FROM AUTHOR]

The properties of hadrons, such as their masses and widths, are predicted to be modified in dense and/or hot nuclear matter. Particular attention has been given to the modifications of vector-meson properties in ordinary nuclear matter where chiral symmetry is predicted to be partially restored due to a change in the quark condensate. Different models predict relatively large measurable changes in the mass and/or the width of these mesons. The e+e- decay channel of these mesons has negligible final-state interactions (FSI), providing an ideal tool to study their possible in-medium modifications Due to its short lifetime, the ρ meson has a substantial probability of decaying in the nucleus and its study has been previously reported. Due to their long lifetimes, the ω and ϕ mesons are ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. These mesons have been photo-produced in several targets ranging from deuterium to lead. Nuclear transparencies ratios have been derived for different decay channels. These ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSATAPS experiment. These results are compared to recent theoretical models. [ABSTRACT FROM AUTHOR]

The Nambu-Jona-Lasinio (NJL)-jet model provides a sound framework for calculating the fragmentation functions in an effective chiral quark theory, where the momentum and isospin sum rules are satisfied without the introduction of ad hoc parameters. The most recent version of the model includes the fragmentation of the light and strange quarks to pions, kaons, nucleons, and antinucleons; where the effects of the production of secondary pions and kaons from the vector mesons ρ, K* and [lowercase_phi_synonym] are also calculated. The results for the model fragmentation function exhibit a qualitative agreement with the empirical parameterizations. The results also allow to test, within the model assumptions, several assumption in parametrizations of the unfavored fragmentation functions used in empirical fits to the experimental data. [ABSTRACT FROM AUTHOR]

Recently there have been considerable interests in studying hadronic states beyond the usual two and three quark configurations. With the renewed experimental interests in σ(600) and the inability of quark model to incorporate too many light scalar mesons, it is quite appropriate to study hadronic states with four quark configurations. Moreover, some of the newly observed charmed hadrons may well be described by four quark configurations. Lattice QCD is perhaps the most desirable tool to adjudicate the theoretical controversy of the scalar mesons and to interpret the structures of the newly observed charmed states. Here we briefly reviewed the lattice studies of four-quark hadrons. [ABSTRACT FROM AUTHOR]

We study the dependence of the ππ scattering phase shifts on the light quark mass in both standard and unitarized SU(2) Chiral Perturbation Theory (ChPT) to one and two loops. We then use unitarized SU(3) ChPT to study the elastic f0(600), κ(800), ρ(770) and K*(892) resonances. The quark masses are varied up to values of interest for lattice studies. We find a very soft dependence on the light quark mass of the ππ phase shifts at one loop and lightly stronger at two loops and a good agreement with lattice results. The SU(3) analysis shows that the properties of the ρ(770) and K*(892) depend smoothly on the quark mass whereas the scalar resonances present a non-analyticity at high quark masses. We also confirm the lattice assumption of quark mass independence of the vector two-meson coupling that, however, is violated for scalars. [ABSTRACT FROM AUTHOR]

ΛcN bound state problem is investigated in the one-meson-exchange potential model. The potentials are obtained from an effective Lagrangian reflecting the heavy quark symmetry, chiral symmetry, and hidden local symmetry. We also consider the contributions from the coupled channels of ΣcN and Σc*N. It is found that the channel coupling is very important in binding the baryons. We find that the formation of the nearly degenerate JP = 0+ and JP = 1+ ΛcN molecular bound states is plausible, although the results are sensitive to the cutoff parameters. [ABSTRACT FROM AUTHOR]

A brief report of some recent experimental developments concerning the X, Y and Z charmoniumlike mesons states and other puzzling states from the BaBar, Belle, BESIII and CDF experiments is presented. [ABSTRACT FROM AUTHOR]

We show that the single, non-photonic electron nuclear modification factor RAAe is affected by the thermal enhancement of the heavy-baryon to heavy-meson ratio in relativistic heavy-ion collisions with respect to proton-proton collisions. We make use of the dynamical quark recombination model to compute such ratio and show that this produces a sizable suppression factor for the RAAe at intermediate transverse momenta. We argue that such suppression factor needs to be considered, in addition to the energy loss contribution, in calculations of RAAe. [ABSTRACT FROM AUTHOR]

We evaluate the pseudoscalar-meson coupling constants and the strangeness-conserving and the strangeness-changing axial charges of octet baryons in lattice QCD with two flavors of dynamical quarks. We find that the coupling constants and the axial charges have rather weak quark-mass dependence and the breaking in SU(3)-flavor symmetry is small at each quark-mass point we consider. [ABSTRACT FROM AUTHOR]

It has long been known that QCD undergoes a deconfining phase transition at high temperature. One of the consequent features of this new, quark-gluon phase is that hadrons become unbounded. In this talk meson correlation functions at non-zero momentum are studied in the deconfined phase using the Maximum Entropy Method. [ABSTRACT FROM AUTHOR]

We discuss the recent progress in calculating the properties of ‘hybrid stars’ (stellar objects similar to neutron stars, classified by the incorporation of non-nucleonic degrees of freedom, including but not limited to hyperons and/or a quark-matter core) using the octet-baryon Quark-Meson Coupling (QMC) model. The version of QMC used is a recent improvement which includes the in-medium modification of the quark-quark hyperfine interaction. [ABSTRACT FROM AUTHOR]

We present results of hypernuclei calculated in the latest quark-meson coupling (QMC) model, where the effect of the mean scalar field in-medium on the one-gluon exchange hyperfine interaction, is also included self-consistently. The extra repulsion associated with this increased hyperfine interaction in-medium completely changes the predictions for Σ hypernuclei. Whereas in the earlier version of QMC they were bound by an amount similar to Λ hypernuclei, they are unbound in the latest version of QMC, in qualitative agreement with the experimental absence of such states. [ABSTRACT FROM AUTHOR]

We extend the quark-meson coupling (QMC) model to incorporate chiral symmetry. The relationship between the QMC model and chiral perturbation theory is also discussed. The nuclear central potential is modified by the effect of internal structure of the nucleon. [ABSTRACT FROM AUTHOR]

I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and antiquarks, including quark—antiquark symmetry in the sea, SU(3) flavour symmetry and SU(6) spin-flavour symmetry. [ABSTRACT FROM AUTHOR]

In this article, the status of the determination of the CKM magnitude |Vub| from inclusive and exclusive semileptonic B decays at the B-factories experiments BaBar and Belle, is reviewed. [ABSTRACT FROM AUTHOR]

Recent results on the so-called XYZ states are presented, including: a near-threshold ωJ/ψ mass peak seen by Belle in the two-photon process γγ→ωJ/ψ; evidence from CDF for a [lowercase_phi_synonym]J/ψ mass peak in B-[lowercase_phi_synonym]J/ψ decays; a Belle search for D*Dπ decays of the 1--Y states; and a Dalitz-plot analysis of B→Kπ±ψ′ decays by Belle that confirms their original claim for the Z(4430)+→π±ψ. [ABSTRACT FROM AUTHOR]

A phenomenological model is employed to treat the rare decays of mesons with neutrino-antineutrino pair production or charged lepton-antilepton production. The model takes advantage of the fact that inside the hadrons, quarks and antiquarks are tightly bound, and they behave like free particles. As such, the rare decay process can be described in terms of the corresponding quark-level decay process, but with the quarks developing ‘dressed’ masses because of QCD effects. The ‘dressed’ quark masses are estimated from the weak decays of the hadrons. With this set of ‘dressed’ quark masses, a reasonable description of the rare decays of the K and B mesons is obtained. [ABSTRACT FROM AUTHOR]

We propose a phenomenological approach based in the meson cloud model to obtain the strange quark structure function inside a kaon, considering the strange quark asymmetry inside the nucleon. [ABSTRACT FROM AUTHOR]

From a necessary condition for “open door” decays of tetraquarks into two pseudoscalar mesons or into a vector and pseudoscalar mesons, we deduce that the lighter states may have strong couplings into these final states. [ABSTRACT FROM AUTHOR]

We argue that the low-lying scalar-meson nonet [1] makes part of a subset of a family of infinitely many scalar-meson nonets, which in turn makes part of a family of infinitely many quark-antiquark bound states and resonances. We outline the properties of this subset. [ABSTRACT FROM AUTHOR]

We review chiral symmetry breaking at the BCS level, in the framework of chiral invariant quark models and in the Schwinger-Dyson formalism. We revisit the π mass problem beyond the BCS level. We show a theorem on the masses, on the widths and on the qq content of the scalar mesons σ and f0. [ABSTRACT FROM AUTHOR]

The article presents a panel discussion that took place at the SCADRON 70: Workshop on "Scalar Mesons and Related Topics", in Lisbon, Portugal, from February 11-16, 2008. Topics included the unquenched glueball spectrum, the existence of the lightest scalar meson and its gluon-quark composition, and various nuclear particle interactions such as π π scattering. Replies to various comments addressed to the physicists are presented.

The first part of this report reviews recent developments at the interface between lattice work on QCD with light dynamical quarks, effective field theory and low energy precision experiments. Then I discuss how dispersion theory can be used to analyze the low energy structure of the ππ scattering amplitude in a model independent manner. This leads to an exact formula for the mass and width of the lowest few resonances, in terms of observable quantities. As an application, I consider the pole position of the σ, paying particular to error propagation in the numerical analysis. The report is based on work done in collaboration with Irinel Caprini and Gilberto Colangelo [1]. [ABSTRACT FROM AUTHOR]

The relationship between mesonic correlations and quantum condensates in the quark matter phase diagram is explored within a quantum field theoretical approach of the Nambu and Jona-Lasinio (NJL) type. Mean-field values in the scalar meson and diquark channels are order parameters signaling the occurrence of quark condensates, entailing chiral symmetry breaking (χSB) and color superconductivity (2SC) in quark matter. We investigate the spectral properties of scalar and pseudoscalar meson excitations in the phase diagram in Gaussian approximation and show that outside the χSB region where the pion is a zero-width bound state, there are two regions where it can be considered as a quasi-bound state with a lifetime exceeding that of a typical heavy-ion collision fireball: (A) the high-temperature χSB crossover region at low densities and (B) the high-density color superconducting phase at temperatures below 100 MeV. [ABSTRACT FROM AUTHOR]

We discuss the charge conjugation quantum number for tetraquarks or meson-meson molecules, seen as possible interpretations of the newly found XYZ charmonium-like resonances. [ABSTRACT FROM AUTHOR]

The newly introduced Transition Distribution Amplitudes (TDAs) are discussed for the π-γ transitions. Relations between π-γ and γ-π TDAs for different cases are given. Numerical values for the π-γ TDAs in different models are compared. GPD’s features are extended to TDAs and the role of PCAC highlighted. We give hints for the evaluation of cross sections for meson pair production in our approach. [ABSTRACT FROM AUTHOR]

A model for anomalous J/Ψ suppression in high energy heavy ion collisions is presented. As the additional suppression mechanism beyond standard nuclear absorption inelastic J/Ψ scattering with hadronic matter is considered. Hadronic matter is modeled as an evolving multi-component gas of point-like non-interacting particles (MCHG). Estimates for the sound velocity of the MCHG are given and the equation of state is compared with Lattice QCD data in the vicinity of the deconfinement phase transition. The approximate cooling pattern caused by longitudinal expansion is presented. It is shown that under these conditions the resulting J/Ψ suppression pattern agrees well with NA38 and NA50 data. [ABSTRACT FROM AUTHOR]

Polarization transfer in quasi-elastic nucleon knockout is sensitive to the properties of the nucleon in the nuclear medium, including possible modification of the nucleon form factor and/or spinor. In our recently completed experiment E03-104 at Jefferson Lab we measured the proton recoil polarization in the 4He(evector ,e′pvector )3H reaction at a Q2 of 0.8 (GeV/c)2 and 1.3 (GeV/c)2 with unprecedented precision. These data complement earlier data between 0.4 and 2.6 (GeV/c)2 from both Mainz and Jefferson Lab. The measured ratio of polarization-transfer coefficients differs from a fully relativistic calculation, favoring either the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model or strong charge-exchange final-state interactions. The measured induced polarizations agree well with the fully relativistic calculation and indicate that these strong final-state interactions may not be applicable. [ABSTRACT FROM AUTHOR]

With the recent measurements on ηc and ηc′ at CLEO, Babar and Belle, and with the prospect of finding the ηb at the Tevatron, it seems appropriate to have another look at the two-photon decay of heavy quarkonium from the standpoint of an effective Lagrangian based on local operator expansion and heavy-quark spin symmetry. In this talk, I would like to discuss a recent work on the two-photon decay rates of ground states and excited states of ηc and ηb using the local operator expansion approach and heavy-quark spin symmetry and taking into account the binding-energy. We find that the predicted two-photon width for ηc agrees well with experiment, but the predicted value for ηc(2S) is twice larger than the CLEO estimation. We point out that the essentially model-independent ratio of ηb two-photon width to the Υ leptonic width and the ηb two-photon width could be used to extract the strong coupling constant αs. [ABSTRACT FROM AUTHOR]

It has been argued long ago that ηb could be observed through the ηb→J/ψ(→μ+μ-)J/ψ(→μ+μ-) decay chain. Recent calculations indicate that the width of ηb into two J/ψ is almost three order of magnitude smaller than the one into the DD*. We study the effects of final state interactions due to the DD* intermediate state on the J/ψJ/ψ final state. We find that the inclusion of this contribution may enhance the short distance branching ratio of about two orders of magnitude. [ABSTRACT FROM AUTHOR]

I present a brief review of results obtained both in open and hidden charm spectroscopy, discussing the interpretation of DsJ(2860), DsJ(2700) and X(3872). [ABSTRACT FROM AUTHOR]

Resonances and enhancements in meson-meson scattering can be divided into two classes distinguished by their behavior as the number of colors (Nc) in QCD becomes large: The first are ordinary mesons that become stable as Nc→∞. This class includes textbook qq mesons as well as glueballs and hybrids. The second class, extraordinary mesons, are enhancements that disappear as Nc→∞; they subside into the hadronic continuum. This class includes indistinct and controversial objects that have been classified as qqqq mesons or meson-meson molecules. Ordinary mesons resemble Feshbach resonances while extraordinary mesons look more like effects due to potentials in meson-meson scattering channels. I build and explore toy models along these lines. [ABSTRACT FROM AUTHOR]

The process of secondary baryon production in π±p collisions at high energies in the central and forward fragmentation regions is considered in the framework of the Quark-Gluon String Model. The contribution of the string-junction mechanism to the baryon production is analysed. The results of numerical calculations are in reasonable agreement with the experimental data on the Λ/A and p/p asymmetries. [ABSTRACT FROM AUTHOR]

The implementation of tensor sources in Chiral Lagrangians allows the computation of Green functions and form factors involving tensor currents, that is, quark bilinears of the form qiσμνqj. Whereas only four new terms show up at O(p4), we find around a hundred of them at O(p6). So it becomes essential to ensure that this set o operators is indeed minimas and non-redundant (i.e., it is a basis). We discuss two phenomenological applications in the context of vector meson resonances and the radiative pion decay. [ABSTRACT FROM AUTHOR]

In this work, the strong coupling constants of the octet baryons to the K and π mesons are studied within the Light Cone QCD sum rule method. It is well known that in the SU(3)f limit, these couplings can be expressed in terms of only 2 constants, so called F and D constants. In this work, the SU(3)f symmetry violating effects are also studied and it is shown that all the coupling constants can be expressed in terms of four analytical functions of the quark parameters. [ABSTRACT FROM AUTHOR]

Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states. [ABSTRACT FROM AUTHOR]

The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how [lowercase_phi_synonym]-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the γvector p→[lowercase_phi_synonym]p reaction, with [lowercase_phi_synonym]→K+K-, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005. [ABSTRACT FROM AUTHOR]

Quark mass dependence induced by one loop corrections to the Breit-Fermi spin-dependent one gluon exchange potential permits an accurate determination of heavy-light meson masses. In this model, the Ds(2317), Ds(2460) and the newly discovered Ds(2700) and Ds(2860) are canonical cs mesons. The multiplet splitting relationship of chiral doublet models, M(1+) - M(1-) = M(0+) - M(0-), holds to good accuracy in the D and Ds systems, but is accidental. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

A survey of the experimental, phenomenological, and theoretical status of the new heavy mesons is presented. States discussed are the Bc, hc, η′c, Ds(2317), Ds(2460), Ds(2700), Ds(2860), X (3872), X (3940), Y (3940), Z (3930), and Y (4260). © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper provides a short overview of our current understanding of exotic mesons. In particular glueballs and hybrids. The lightest glueball appears to be where lattice predicts it to be, but is fully mixed with two neighboring mesons. The situations with hybrids is less clear. There are hints of π1 states, but both the confirmation of these states as well as the mapping of exotic nonets awaits future experiments. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]