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Register a new userRecent progress on hadron spectroscopy from lattice QCD
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Jozef J. Dudek
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Lattice QCD has matured to a degree where it is now possible to study excited hadrons as they truly appear in nature, as short-lived resonant enhancements decaying into multiple possible final states. Through variational analysis of matrices of correlation functions computed with large bases of interpolating fields it has proven possible to extract many excited state energy levels, and these can be used to constrain the hadron-hadron scattering amplitudes in which hadron resonances can be observed. Recent progress is illustrated with several examples including coupled-channel scattering in the $pi eta, Koverline{K}$ and $pipi, Koverline{K}, etaeta$ systems in which the $a_0, f_0$ scalar mesons appear.
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We present our most recent investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement [JHEP 1009:073, 2010]. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP 0906:088 (2009)] by choosing even finer lattices ($N_t$=16) and we work again with physical quark masses. All these results are confronted with the predictions of the Hadron Resonance Gas model and Chiral Perturbation Theory for temperatures below the transition region. Our results can be reproduced by using the physical spectrum in these analytic calculations. A comparison with the results of the hotQCD collaboration is also discussed.
Our progress in computing the spectrum of excited baryons and mesons in lattice QCD is described. Sets of spatially-extended hadron operators with a variety of different momenta are used. A new method of stochastically estimating the low-lying effects of quark propagation is utilized which allows reliable determinations of temporal correlations of both single-hadron and multi-hadron operators. The method is tested on the isoscalar mesons in the scalar, pseudoscalar, and vector channels, and on the two-pion system of total isospin I=0,1,2.
Recent progress and the latest results on the bulk thermodynamic properties of QCD matter from lattice are reviewed. In particular, I will stress upon the fact that lattice techniques are now entering into precision era where they can provide us with new insights on even the microscopic degrees of freedom in different phases of QCD. I will discuss some instances, from the recent studies of topological fluctuations and screening masses. The progress towards understanding the effects of anomalous $U_A(1)$ symmetry on the chiral crossover transition and transport properties of QCD matter will also be discussed.
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