Antenna showers with hadronic initial states

We present an antenna shower formalism including contributions from initial-state partons and corresponding backwards evolution. We give a set of phase-space maps and antenna functions for massless partons which define a complete shower formalism suitable for computing observables with hadronic initial states. We focus on the initial-state components: initial–initial and initial–final antenna configurations. The formalism includes comprehensive possibilities for uncertainty estimates. We report on some preliminary results obtained with an implementation in the Vincia antenna-shower framework.     

Resonance states in an effective chiral hadronic model

With an effective chiral flavour SU(3) model we show the effect of hadronic resonances on the QCD phase diagram. We state that varying the resonance couplings to the scalar and vector fields affects the order and location of the phase transition, the possible existence of a critical end point (CEP), and the thermodynamic properties. We present (strange) quark number susceptibilities at zero baryochemical potential and at three different points at the phase transition. Comparing results to lattice QCD, we state that reasonable large vector couplings limit the phase transition to a smooth crossover ruling out a CEP.     

New hadronic states observed at BES II

The report includes the new observation of X(1835) in J/ψ→γη ^′ π ⁺ π ^-, the ωφ threshold enhancement in J/ψ→γωφ, the ωω structure in J/ψ→γωω and the broad 1^- structure at the low K ⁺ K ^- invariant-mass spectrum in J/ψ→K ⁺ K ^- π ⁰.     

Self-consistency in non-extensive thermodynamics of highly excited hadronic states

The self-consistency of a thermodynamical theory for hadronic systems based on the non-extensive statistics is investigated. We show that it is possible to obtain a self-consistent theory according to the asymptotic bootstrap principle if the mass spectrum and the energy density increase q-exponentially. A direct consequence is the existence of a limiting effective temperature for the hadronic system. We show that this result is in agreement with experiments.     

Baryon resonances as hadronic molecule states with kaons

We investigate hadronic molecule states of $K \bar K N$ and $\bar K \bar K N$ systems with I?=?1/2 and J ^P ?=?1/2^?+?, assuming that Λ(1405) and the scalar mesons, f ₀(980), a ₀(980), are reproduced as quasi-bound states of $\bar KN$ and $K \bar K$ . Performing non-relativistic three-body calculations for these systems, we find weakly bound states for $K \bar K N$ and $\bar K \bar K N$ around 1900 MeV, which correspond to new baryon resonances of N ^* and Ξ ^* with J ^P ?=?1/2^?+?. We find that these resonances have cluster structure of the two-body bound state keeping its properties as in the isolated two-particle system.     

Nucleon-nucleon scattering in the quark-cluster model

Results of calculations of nucleon-nucleon scattering phase shifts (S-, P- and D-wave) and delta-production cross sections are presented for a quark potential model with channel coupling in both generator-coordinate and resonating-group formalisms. The dependence of the results on various input assumptions is shown. The interpretation in terms of a local potential is discussed, as are the extensions to the calculation necessary for agreement with experiment.     

Radial excitation of hadronic states with null pontryagin index

Radial excitations of hadrons carrying zero instanton number are investigated. The mass relations among relevant non-strange and strange mesons and baryons have been derived consistently with the observed data.     

Possible hadronic molecular states composed of S-wave heavy-light mesons

We perform a systematical study of possible molecular states composed of the S wave heavy light mesons,where the S–D mixing and η-η' mixing are explicitly included.Our calculation indicates that the observed X(3872) could be a loosely shallow molecular state composed of D*+ h.c,while neither Z_c(3900)/Z_c(4020) nor Z_b(10610)/Z_b(10650) is supported to be a molecule.Some observed possible molecular states are predicted,which could be searched for by further experimental measurements.     

Parity-violating spin asymmetries in polarized proton-proton scattering with hadronic final states

Longitudinal, parity-violating single spin asymmetries in proton-proton collisions for RHIC kinematics are considered. The focus of this study is on the production of a single jet as well as a hadron containing a charm quark. While the asymmetry for jets is rather small, considerably larger effects can be expected for the production of charm because of the strongly reduced QCD background. The general outcome of a fixed order calculation is not much affected by the resummation of large threshold logarithms.     

Search for promptly produced heavy quarkonium states in hadronic Z decays

A search has been made for direct production of heavy quarkonium states in more than 3 million hadronic Z ⁰ decays in the 1991–1994 DELPHI data. Prompt J/ψ, ψ(2S) and Υ candidates have been searched for through their leptonic decay modes using criteria based on the kinematics and decay vertex positions. New upperlimits are set at the 90% confidence level for Br(Z⁰ → (QQ) X)/Br (Z⁰ → hadrons) for various strong production mechanisms of J/ψ and Υ these range down to 0.9 × 10^?4. The limits are set in the presence of a small excess (～ 1% statistical probability of a background fluctuation) in the sum of candidates from prompt J/ψ, ψ(2S), Υ(1S),Υ(2S) and Υ(3S) relative to the estimated background.     

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

We study the properties of D and [`(D)] \bar{{D}} mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of D and [`(D)] \bar{{D}} mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). The nucleons, hyperons, the scalar isoscalar meson, σ and the scalar-isovector meson, d \delta as modified in the strange hadronic matter, modify the masses of D and [`(D)] \bar{{D}} mesons. It is found that, as compared to the [`(D)] \bar{{D}} mesons ([`(D<sup>0</sup>)] \bar{{D^0}}, D <sup>−</sup>), the properties of the D mesons (D <sup>0</sup>, D <sup>+</sup>) are more sensitive to the isospin asymmetry at high densities. On the other hand, the effects of strangeness fraction are found to be more dominant for the [`(D)] \bar{{D}} mesons as compared to the D mesons and these modifications are observed to be particularly appreciable at high densities. We also study the mass modifications of the charmonium states J/ψ, ψ(3686) and ψ(3770) in the isospin asymmetric strange hadronic matter at finite temperatures and investigate the possibility of the decay of the charmonium states into D [`(D)] \bar{{D}} pairs in the hot hadronic medium. The mass modifications of these charmonium states arise due to their interaction with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within the effective chiral model. The effects of finite quark masses are taken into account in the trace of the energy momentum tensor in QCD, while investigating the medium modification of the charmonium masses through the modification of the gluon condensate in the medium. We also compute the partial decay widths of the charmonium states to the D [`(D)] \bar{{D}} pairs in the hadronic medium. The strong dependence on density of the in-medium properties of the D, [`(D)] \bar{{D}} and the charmonium states, as well as the partial decay widths of charmonium states to D [`(D)] \bar{{D}} pairs, found in the present investigation, will be of direct relevance in observables like open charm enhancement as well as J/ψ suppression in the compressed baryonic matter (CBM) experiments at the future Facility for Antiproton and Ion Research, GSI, where the baryonic matter at high densities is planned to be produced.     

Bound states of light and heavy quarks in hot hadronic matter

The correlators of currents \(\bar q\) Q,γ _v γ ₅ Q,q andQ being correspondingly light and heavy quark fields, in hot hadronic matter are investigated by means of finite temperature QCD sum rules. AtT? 100 MeV the modification of the effective spectrum parameters takes place, similar to that found earlier in the correlators of light quark currents. AtT?150 MeV the form of the spectrum is obtained, which indicates an appearance in hadronic matter of quasifree quarks with nonzero mass being fixed by the value of the quark condensate 〈 \(\bar q\) q〉 (T).     

On the production of hidden-flavored hadronic states at high energy

I discuss the production mechanism of hidden-flavored hadrons at high energy. Using e+e-collisions and light-meson pair production in high energy exclusive processes, I demonstrate that hidden quark pairs do not necessarily participate in short-distance hard scattering. Implications are then explored in a few examples. Finally, I discuss the production mechanism of X(3872) in hadron collisions, where some misunderstandings have arisen in the literature.     

A corresponding-state approach to quark-cluster matter

The state of super-dense matter is essential for us to understand the nature of pulsars; however, non- perturbative quantum chromodynamics makes it very difficult to make direct calculations of the state of cold matter at realistic baryon number densities inside compact stars. Nevertheless, from an observational point of view, it is conjectured that pulsars could be made up of quark clusters since the strong coupling between quarks might render the quarks to be grouped in clusters. In this paper, we attempt to find an equation of state of condensed quark-cluster matter in a phenomenological way. Supposing that the quark-clusters could be analogized to inert gases, we apply here the corresponding-state approach to derive the equation of state of quark-cluster matter, as was similarly demonstrated for nuclear and neutron-star matter in the 1970s. According to the calculations that we have presented, the quark-cluster stars, which are composed of quark-cluster matter, could have a high maximum mass that is consistent with observations and, in turn, further observations of pulsar mass could also place a constraint on the properties of quark-cluster matter. We will also briefly discuss the melting heat during the solid-liquid phase conversion and its related astrophysical consequences.     

On the ω dependence of exclusive hadronic final states in lepton-hadron scattering

A framework is presented for studying the ω dependence of exclusive hadronic final states in lepton-hadron scattering (ω being Bjorken's scaling variable 2Mv/Q²). This is used for the analysis of K∫, KΛ, πN and πΔ final states.     

The use of QCD in hadronic cascades between heavy quark-antiquark bound states

We argue that a perturbative calculation of the spectra and rates of hadronic transitions between heavy quark-antiquark bound states makes sense within QCD provided suitable spin-parity projections are performed. Applications are made to various kinds of cascades. We obtain the correct ψ′ → J/ψππ mass spectrum. The cascades involving the emission of at least three gluons appear very strongly suppressed as compared to those allowing two-gluon emission. Application to the ? family is made.     

Antenna subtraction at NNLO with hadronic initial states: initial-final configurations

We extend the antenna subtraction method to include initial states containing one hadron at NNLO. We present results for all the necessary subtraction terms, antenna functions, for the master integrals required to integrate them over the relevant phase space and finally for the integrated antennae themselves. Where applicable, our results are cross-checked against the known NNLO coefficient functions for deep inelastic scattering processes.