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I discuss the phase diagram of QCD in the large \(N_c\) limit. Quarkyonic Matter is described. The properties of QCD matter as measured in the abundance of produced particles are shown to be consistent with this phase diagram. A possible triple point of Hadronic Matter, Deconfined Matter and Quarkyonic Matter is shown to explain various behaviors of ratios of particle abundances seen in CERN fixed target experiments.

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Neutron stars represent excellent physical systems for the study of the high density QCD phase transition that might occur in their core. A promising line of research concerns the possible signatures of the dynamics of the formation of quark matter in a neutron star. We review the different signatures that have been recently proposed in connection with explosive phenomena such as supernovae, gamma-ray-bursts, merger of neutron stars.

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In-medium chiral symmetry breaking in confining potential models of QCD is examined. Ring diagrams are proposed as a resolution to the infrared divergence problem in the gap equations. We present the first determination of the temperature-density phase diagram for two model systems. We find that observables and the phase structure of the confinement models depend strongly on whether vacuum polarisation is accounted for. Finally, it appears that standard confinement models cannot adequately describe both hadron phenomenology and in-medium properties of QCD.

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We discuss phases in dense hadronic and quark matter from chiral model approaches. Within PNJL models the phase diagram for various number of colors \(N_c\) is studied. How phases are constrained in quantum field theories is also discussed along with the anomaly matching. An exotic phase with unbroken center symmetry of chiral group has a characteristic feature in the thermodynamics, which can be interpreted as one realization of the quarkyonic phase in QCD for \(N_c=3\).

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The ATLAS detector was designed primarily for proton–proton collisions but it will also participate in the heavy ion program of the Large Hadron Collider (LHC). The LHC will collide lead ions at the center of mass energy of \(\sqrt {s_{NN}}=5.5\) TeV (with \(\sqrt {s_{NN}}=2.75\) TeV expected in 2010) and thus it will provide crucial information about the hot and dense QCD matter expected to be formed in these collisions. We will take advantage of unprecedented capabilities of the ATLAS detector to measure global observables such as collective flow and particle multiplicities as well as jet quenching and modification of the high \(p_{\mathrm {T}}\) particle spectra and heavy-quarkonia suppression. Performance of the ATLAS detector to measure these phenomena is presented.

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A quasiparticle description of pure glue QCD below \(T_{\rm c}\) is presented. It is shown that the strong decrease of the gluon condensate combined with the increasing thermal width of the lightest glueballs at \(T\lesssim T_{\rm c}\) might be the trigger of the phase transition. The proposed model compares very well with recent lattice data.

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The role of color-magnetic monopoles in a pure gauge plasma at high temperature \(T\gt 2T_{\rm c}\) is considered. In this temperature regime, monopoles can be considered heavy, rare objects embedded into matter consisting mostly of the usual “electric” quasiparticles, quarks and gluons. The gluon–monopole scattering is found to hardly influence thermodynamic quantities, yet it produces a large transport cross-section, significantly exceeding that for pQCD gluon–gluon scattering up to quite high \(T\). This mechanism keeps viscosity small enough for hydrodynamics to work at LHC.

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Recent work by Chernodub and Ilgenfritz has uncovered nontrivial temperature dependence in the electric–magnetic asymmetry in the dimension-2 condensate. This asymmetry measures the difference between the spatial and the temporal components of the \(\langle A_\mu ^2\rangle \) condensate. Lattice computations have shown very interesting phenomena. The asymmetry shows a jump at the deconfinement phase transition, beyond which it approaches its perturbative value. At temperatures lower than the critical temperature, it shows an exponential behavior with a mass in the exponent smaller than the lowest glueball mass. In this talk we present the research done on this asymmetry, using a generalization of analytical methods developed to study \(\langle A_\mu ^2\rangle \). The purpose is to shed more insight on the findings of Chernodub and Ilgenfritz.

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We consider the energy momentum tensor of (linearized) relativistic hydrodynamics to all orders in fluid velocity gradient expansion. We apply the AdS/CFT duality for \({\cal N}=4\) SUSY in order to compute the retarded correlators of the energy-momentum tensor. From these correlators we determine a large set of transport coefficients of third- and fourth-order hydrodynamics and propose a new all order resummation model.

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It is explained why and how the fireball created in ultrarelativistic nuclear collisions can fragment when passing the phase transition. It can happen at the first-order phase transition but is not excluded even at high collision energies where the smooth crossover is present. Two potential observables sensitive to the appearance of fragmentation are reviewed: event-by-event changes of rapidity distributions and proton correlations in relative rapidity.

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I describe the parton picture at strong coupling emerging from the gauge/gravity duality and some of its phenomenological consequences for high-energy scattering. I focus on the hard probes of a strongly coupled plasma, as potentially relevant for heavy collisions at RHIC and LHC.

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Using the formalism of \(k_{\rm t}\)-factorization we study exclusive photoproduction of lepton pairs \(\gamma p \to l^+ l^- p\) at high energies \( W_{\gamma p} \gt 100\) GeV. Predictions for the \(\gamma p \to l^+ l^- p\) reactions are given using an unintegrated gluon distribution. We calculate the invariant mass distribution of the lepton pair at different energies. We also discuss whether the production of timelike virtual photons can be approximated by continuing to the spacelike domain \(q^2 \lt 0\). The amplitude will be used to predict the cross-section for exclusive production of lepton pair in hadronic reaction.

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In hard processes on heavy nuclei, multiple gluon exchanges are enhanced by the size of the target. As a consequence, the familiar linear \(k_\perp \)-factorization is broken, and must be replaced by a new, nonlinear \(k_\perp \)-factorization, where hard scattering observables are in general nonlinear functionals of a properly defined nuclear unintegrated glue. We discuss the small-\(x\) evolution properties of the nuclear glue as well as of quasielastic cross-sections. In addition, we discuss how photon-jet correlations depend on the nuclear unintegrated glue.

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Developed since the early 60s, the Standard Model is a powerful framework describing physics at the subatomic scale. It has achieved great successes, such as the prediction of the top quark, discovered in 1995 at Tevatron. However, one of the central piece of this model, the Higgs boson, has still not been observed. What if it is not discovered at the Tevatron or LHC? What type of new physics will we look for, and what will this imply? This paper will present an alternative mechanism for the breaking of the electroweak symmetry: Technicolor. In this theory, the Higgs mechanism is replaced by new strong interactions. This solves some of the issues of the Standard Model, such as the Hierarchy problem. Early Technicolor models have been ruled out by precision electroweak measurements. We will describe more recent types of Technicolor models, which pass those tests, and are currently searched for at collider experiments. After a brief introduction to Technicolor models, we will focus on the current experimental status. We will then describe what searches will be conducted at the LHC experiments in order to discover or exclude Technicolor.

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Within a simple Ansatz for renormalized gluon propagator and using gauge invariant pinch-technique for Schwinger–Dyson equation, the limits on the effective gluon mass is derived. We calculated scheme invariant running coupling, which in order to be well defined, gives the lower limit on the gluon mass. We conclude that mass, \(m\), should be larger than \(0.4\,{\mit \Lambda }\) in order to avoid Landau ghost. The upper limit is estimated from assumed quark mass generation which requires gauge coupling must be large enough to trigger chiral symmetry breaking. It allows only small range of \(m\), which lead to a reasonably large infrared coupling. Already for \(m\simeq {\mit \Lambda }\) we get no chiral symmetry breaking at all. Further, we observe that sometimes assumed or postulated Khallen–Lehmann representation for running coupling is not achieved for any value of \(m\).

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We discuss a possibility for existence of confining but chirally symmetric phase at large baryon densities and low temperatures.

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Nucleons are complex systems of confined quarks and exhibit characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Observing and understanding these higher-mass resonances is crucial, but they are difficult to observe since they are broad and overlapping. Very often, these higher-lying states reveal themselves more clearly through interference with dominant amplitudes. The interference terms can be isolated via polarization observables. At Jefferson Lab, extensive data sets on photo- as well as electro-production of pseudo-scalar mesons (\(\pi \), 2\(\pi \), \(\eta \), \(K\)) and vector mesons (\(\rho \), \(\omega \), \(\phi \)) have been accumulated over the last few years using the CLAS spectrometer. The current efforts with CLAS focus on utilizing highly-polarized hydrogen and deuterium targets in combination with polarized photon beams toward a complete measurement of a large number of reaction channels. This contribution discusses recent results on single- and double-pion photoproduction.

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The number of experimentally known baryon states is noticeably smaller than those predicted by existing models. The situation became even more tense after latest analysis of the \(\pi N\) elastic reaction which did not confirm many “well known” states. In this paper the status of the Bonn–Gatchina partial wave analysis is reported. It is shown that data from inelastic pion-induced reactions provide a crucial information about P-wave baryon resonances, which were not observed in the latest analysis of the elastic data.

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We study the QCD phase diagram, in particular we study the critical points of the two main QCD phase transitions, confinement and chiral symmetry breaking. Confinement drives chiral symmetry breaking and, due to the finite quark mass, at small density both transitions are a crossover, while they are a first or second order phase transition in large density. We study the QCD phase diagram with a quark potential model including both confinement and chiral symmetry. This formalism, in the Coulomb gauge Hamiltonian formalism of QCD, is presently the only one able to microscopically include both a quark–antiquark confining potential and a vacuum condensate of quark–antiquark pairs. This model is able to address all the excited hadrons, and chiral symmetry breaking, at the same token. Our order parameters are the Polyakov loop and the quark mass gap. The confining potential is extracted from the Lattice QCD data of the Bielefeld group. We order to address how the quark masses affect the critical point location in the phase diagram.

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High-precision calculations of hadron spectroscopy are a crucial task for lattice QCD. State-of-the-art techniques are needed to disentangle the contributions from different energy states, such as solving the generalized eigenvalue problem (GEVP) for zero-momentum hadron correlators in an efficient way. We review the method and discuss its application in the determination of the \(B_s\)-meson spectrum using (quenched) nonperturbative HQET at the order of \(1/m_b\).

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Some problems with theoretical foundations of bottom-up holographic models are briefly discussed. It is pointed out that the spectroscopic aspects of these models in principle do not require the AdS/CFT prescriptions and may be interpreted as just an alternative language expressing the phenomenology of QCD sum rules in the large-\(N_c\) limit. A general recipe for incorporation of the chiral symmetry breaking scale into the soft-wall holographic models is proposed.

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Exotic antidecuplet baryons are predicted to be not only surprisingly light but also very narrow. First, we explain how small decay width arises in the quark soliton model. Next, we study possible mixing of exotic antidecuplet with Roper octet and discuss its phenomenological consequences.

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We study the implications of a light tetraquark on the chiral phase transition at nonzero temperature \(T\): the behavior of the chiral and four-quark condensates and the meson masses are studied in the scenario in which the resonance \(f_{0}(600)\) is described as a predominantly tetraquark state. It is shown that the critical temperature is lowered and the transition softened. Interesting mixing effects between tetraquark and quarkonium configurations take place.

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Most excited hadrons have multiparticle strong decay modes, which can often be described as resulting from intermediate states containing one or two resonances. In a theoretical approach, such a description in terms of quasi-two-particle initial and final states leads to unitarity violations, because of the complex masses of the involved resonances. In the present paper, an empirical algebraic procedure is presented to restore unitarity of the \(\mathcal {S}\)-matrix while preserving its symmetry. Preliminary results are presented in a first application to \(S\)-wave \(\pi \pi \) scattering, in the framework of the Resonance-Spectrum Expansion.

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Measurements of the \(pp\to ppK^+K^-\) reaction, performed near the kinematical threshold with the experiment COSY-11 at the Cooler Synchrotron COSY, reveal a significant discrepancy between obtained excitation function and theoretical expectations neglecting interactions of kaons. In order to deepen our knowledge about the low energy dynamics of the \(ppKK\) system we investigated population of events for the \(pp\to ppK^+K^-\) reaction as a function of the invariant masses of two particle subsystems. Based for the first time on the low-energy \(K^+K^-\) invariant mass distributions and the generalized Dalitz plot analysis, we estimated the scattering length for the \(K^+K^-\) interaction.

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We discuss the status of the pion distribution amplitude (DA) in connection with QCD sum rules and experimental data on the \(\gamma ^*\gamma ^*\to \pi ^0\) transition form factor. Contents: (a) Pion DA in generalized QCD Sum Rules (SRs); (b) Light Cone Sum Rules (LCSR) analysis of the CLEO data for the \(\gamma ^*\gamma \to \pi ^{0}\) transition form factor; (c) Recent lattice QCD data for the pion DA; (d) BaBar data — a challenge for QCD?

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In the next few months the KLOE-2 detector is expected to start data taking at the upgraded DA\(\rm {\Phi }\)NE \(\phi \)-factory of INFN Laboratori Nazionali di Frascati. It aims to collect 25 fb\(^{-1}\) at the \(\phi (1020)\) peak, and about 5 fb\(^{-1}\) in the energy region between 1 and 2.5 GeV. We review the status and physics program of the project.

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We present results on the isospin dependence of the \(\eta '\) production cross-section in nucleon–nucleon collisions, as well as the results of comparative analysis of the invariant mass distributions for the \(pp\to pp\eta '\) and \(pp\to pp\eta \) reactions in the context of the proton–\(\eta \) and proton–\(\eta '\) interaction. Additionally, the value of the total width of the \(\eta '\) is reported as derived directly from the measurement of the mass distribution and an explanation of the experimental technique used in order to achieve a precision about an order of magnitude better then former experiments is included.

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We calculate low-energy meson decay processes and pion–pion scattering lengths in a globally chirally invariant two-flavour linear sigma model exploring the quark content of the scalar mesons \(f_{0}(600)\) and \(a_{0}(980)\), as well as \(f_{0}(1370)\) and \(a_{0}(1450)\). To this end, we investigate which one of these sets of fields is more likely to contain quark–antiquark states.

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The mass matrix for \(\eta \)–\(\eta ^\prime \) is derived in the flavor basis at \({\cal O}(p^4)\) of the chiral Lagrangian using the large \(N\) approximation. Under certain assumptions, the mixing angle \(\phi =41.4^\circ \) and the decay constants ratio \(f_K/f_\pi =1.15\) are calculated and in agreement with the data. It appears that the FKS scheme arises as a special limit of the chiral Lagrangian.

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Searches for tetraquarks and mesonic molecules in lattice QCD are briefly reviewed. In the light quark sector the most serious candidates are the lightest scalar resonances \(\sigma \), \(\kappa \), \(a_0\) and \(f_0\). In the hidden-charm sector I discuss lattice simulations of \(X(3872)\), \(Y(4260)\), \(Y(4140)\) and \(Z^+(4430)\). The most serious challenge in all these lattice studies is the presence of the scattering states in addition to possible tetraquark/molecular states. The available methods for distinguishing both are reviewed and the main conclusions of the simulations are presented.

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The \(X(3872)\) is studied as an axial-vector charmonium state in the multichannel framework of the Resonance-Spectrum Expansion quark–meson model, previously applied to a variety of other puzzling mesonic resonances. Included are the open-charm pseudoscalar–vector and vector–vector channels, the most important of which is the S-wave \(\bar {D}^{*0}D^{0}\)+\(D^{*0}\bar {D}^{0}\) channel, which practically coincides with the \(X(3872)\) structure. The two free parameters of the model are tuned so as to roughly reproduce the \(\chi _{c1}(3511)\) mass as well as the enhancement just above the \(\bar {D}^{*0}D^{0}\)/\(D^{*0}\bar {D}^{0}\) threshold. The present model is able to describe the shape of the latter data quite well. However, as no dynamical resonance pole is found, the \(X(3872)\) and \(X(3940)\) cannot be reproduced simultaneously, at this stage. A possible further improvement is discussed.

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The importance of QCD-like theories in Beyond the Standard Model physics is briefly reviewed.

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The colour fields, created by a static gluon–quark–antiquark system, are computed in quenched SU(3) lattice QCD, in a \(24^3\times 48\) lattice at \(\beta =6.2\) and \(a=0.07261(85)\) fm. We study two geometries, one with a U shape and another with an L shape. The particular cases of the two-gluon glueball and quark–antiquark are also studied, and the Casimir scaling is investigated in a microscopic perspective. This also contributes to understand confinement with flux tubes and to discriminate between the models of fundamental versus adjoint confining strings, analogous to type-II and type-I superconductivity.

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The strong suppression of hadrons with large transverse momentum (\(p_{\rm T}\)) in central \({\rm Au}+{\rm Au}\) collisions observed at RHIC is generally interpreted as a consequence of energy loss of energetic partons in the hot and dense matter before fragmenting. The study of heavy quark production is testing our understanding of this scenario. The recent results on heavy flavor measurements from the STAR and PHENIX experiments at RHIC will be presented. The total charm production cross-section extracted in \(d+{\rm Au}\), \({\rm Cu}+{\rm Cu}\) and \({\rm Au}+{\rm Au}\) collisions at \(\sqrt {s_{NN}}=200\) GeV scales with the number of binary collisions. The high \(p_{\rm T}\) non-photonic electron spectra show an unexpectedly strong suppression in central \({\rm Au}+{\rm Au}\) collisions. Current theoretical models do not explain this observation satisfactory. The relative contribution of charm and bottom decays to non-photonic electrons was experimentally extracted. The measurements of \(J/{\mit \Psi }\) and \({\mit \Upsilon }\) production are considered as a leading probe of Quark Gluon Plasma (QGP) properties. Recent STAR and PHENIX results in quarkonia sector will be presented and discussed.

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The HFT is a silicon detector for the STAR experiment at RHIC. It is replacing the decommissioned silicon drift detector (SVT) with active pixel technology close to the beam pipe in order to achieve about an order of magnitude better track pointing (DCA) resolution. This will allow for a direct and full topological reconstruction of charmed meson decays (e.g. \(D^0\)) and a better determination of the \(B\)-meson spectra. Key measurements include \(D^0\) elliptic flow (\(v_2\)) determination, especially in the lower transverse momenta (\(p_{\rm T}\)) region, and identified heavy quark suppression studies at high \(p_{\rm T}\) via the nuclear modification factor (\(R_{\rm CP}\) and \(R_{AA}\)).

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An evidence for a narrow nucleon resonance with the mass of \(M\sim 1.685\) GeV in the Compton scattering on the neutron is presented. The resonance possesses unusual properties: the narrow width \({\mit \Gamma } \leq 30\) MeV, and the much stronger photocoupling to the neutron than to the proton. We also added some remarks and simple estimates on putative narrow nucleon N\(^*\)(1685) in the \(\eta \) photoproduction on the nucleon.

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We review selected highlights of the STAR experiment at RHIC, focusing on results on strangeness production, elliptic flow and the recent discovery of antihypertriton in Au\(\,+\,\)Au collisions at 200 GeV. While the hypertriton has been discovered earlier by other experiments, antihypernuclei have never been observed. This result extends the nuclear chart into antimatter with strangeness.

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We present theoretical estimates of the expected ratios of yields of hypernuclei and antihypernuclei in Au\(\,+\,\)Au collisions at \(\sqrt {s_{NN}} = 200\) GeV within the framework of a thermal model. This model can successfully reproduce the ratios of other hadrons produced in heavy ion collisions at RHIC energy. The prediction are compared to recent data of the STAR experiment at RHIC, aiming to elucidate the production mechanism of hypernuclei and antihypernuclei in heavy ion collisions at RHIC.