115815562
On the convergence of multi-channel effective interactions
A detailed analysis of convergence properties of the Andreozzi-Lee-Suzuki iteration method, which is used for the calculation of low-momentum effective potentials Vlowk is presented. After summarizing different modifications of the iteration method for one-flavor channel we introduce a simple model in order to study the generalization of the iteration method to multi-flavor channels. The failure of a straightforward generalization is discussed. The introduction of a channel-dependent cutoff cures the conceptual and technical problems. This novel method has already been applied successfully for realistic hyperon-nucleon interactions.
17501397
Low-momentum hyperon-nucleon interactions
We present a first exploratory study for hyperon-nucleon interactions using renormalization group techniques. The effective two-body low-momentum potential ${V}_{\text{low}\phantom{\rule{0.3em}{0ex}}k}$ is obtained by integrating out the high-momentum components from realistic Nijmegen YN potentials. A T-matrix equivalence approach is employed, so that the low-energy phase shifts are reproduced by ${V}_{\text{low}\phantom{\rule{0.3em}{0ex}}k}$ up to a momentum scale $\ensuremath{\Lambda}~500$ MeV. Although the various bare Nijmegen models differ somewhat from each other, the corresponding ${V}_{\text{low}\phantom{\rule{0.3em}{0ex}}k}$ interactions show convergence in some channels, suggesting a possible model-independent YN interaction at low momenta.
62901349
Charge Fluctuations as Thermometer for Heavy-Ion Collisions
We present a determination of freeze-out conditions in heavy-ion collisions based on ratios of cumulants of net electric charge fluctuations obtained from lattice QCD. These ratios can reliably be calculated for a wide range of chemical potential values by using a next-to-leading order Taylor series expansion around the limit of vanishing baryon, electric charge and strangeness chemical potentials. We first determine the strangeness and electric charge chemical potentials that characterize the conditions in heavy ion collisions at RHIC and LHC. We then show that a comparison of lattice QCD results for ratios of up to third order cumulants of electric charge fluctuations with experimental results allows us to extract the freeze-out baryon chemical potential and the freeze-out temperature. We apply our method to preliminary data of the STAR and PHENIX collaborations.
119170993
Thermodynamics of (2+1)-flavor QCD: Confronting models with lattice studies
The Polyakov-quark-meson model, which combines chiral as well as deconfinement aspects of strongly interacting matter, is introduced for three light quark flavors. An analysis of the chiral and deconfinement phase transition of the model and its thermodynamics at finite temperatures is given. Three different forms of the effective Polyakov-loop potential are considered. The findings of the 2+1 flavor model investigations are compared to corresponding recent QCD lattice simulations of the RBC-Bielefeld, HotQCD and Wuppertal-Budapest collaborations. The influence of the heavier quark masses, which are used in the lattice calculations, is taken into account. In the transition region the bulk thermodynamics of the Polyakov-quark-meson model agrees well with the lattice data.
53496974
Towards finite density QCD with Taylor expansions
Abstract Convergence properties of Taylor expansions of observables, which are also used in lattice QCD calculations at non-zero chemical potential, are analyzed in an effective N f = 2 + 1 flavor Polyakov quark–meson model. A recently developed algorithmic technique allows the calculation of higher-order Taylor expansion coefficients in functional approaches. This novel technique is for the first time applied to an effective N f = 2 + 1 flavor Polyakov quark–meson model and the findings are compared with the full model solution at finite densities. The results are used to discuss prospects for locating the QCD phase boundary and a possible critical endpoint in the phase diagram.
118463111
The Three-flavor chiral phase structure in hot and dense QCD matter
Chiral symmetry restoration at nonzero temperature and quark densities are investigated in the framework of a linear sigma model with N{sub f}=3 light quark flavors. After the derivation of the grand potential in mean-field approximation, the nonstrange and strange condensates, the in-medium masses of the scalar and pseudoscalar nonets are analyzed in hot and dense medium. The influence of the axial anomaly on the nonet masses and the isoscalar mixings on the pseudoscalar {eta}-{eta}{sup '} and scalar {sigma}(600)-f{sub 0}(1370) complex are examined. The sensitivity of the chiral phase transition as well as the existence and location of a critical end point in the phase diagram on the value of the sigma mass are explored. The chiral critical surface with and without the influence of the axial U(1){sub A} anomaly is elaborated as a function of the pion and kaon masses for several values of the sigma mass.
61399113
Hough Transform Based Pattern Recognition for the $\overline{P}$ANDA Forward Tracking System
7348824
The continuum limit of the static-light meson spectrum
We investigate the continuum limit of the low lying static-light meson spectrum using Wilson twisted mass lattice QCD with Nf = 2 dynamical quark flavours. We consider three values of the lattice spacing a ≈ 0.051 fm, 0.064 fm, 0.080 fm and various values of the pion mass in the range 280 MeV ≲ mPS 640 MeV. We present results in the continuum limit for light cloud angular momentum j = 1/2, 3/2, 5/2 and for parity $ \mathcal{P} = +, - $. We extrapolate our results to physical quark masses, make predictions regarding the spectrum of B and Bs mesons and compare with available experimental results.
29909987
Fermions in the pseudoparticle approach
The pseudoparticle approach is a numerical technique to compute path integrals without discretizing spacetime. The basic idea is to integrate over those field configurations, which can be represented by a sum of a fixed number of localized building blocks (pseudoparticles). In a couple of previous papers we have successfully applied the pseudoparticle approach to pure SU(2) Yang-Mills theory. In this work I discuss how to incorporate fermionic fields in the pseudoparticle approach. To test the method, I compute the phase diagram of the 1 + 1-dimensional Gross-Neveu model in the large-N limit.
16569966
Fermionic fields in the pseudoparticle approach
The pseudoparticle approach is a numerical method to compute path integrals without discretizing spacetime. The basic idea is to consider only those field configurations, which can be represented as a linear superposition of a small number of localized building blocks (pseudoparticles), and to replace the functional integration by an integration over the pseudoparticle degrees of freedom. In previous papers we have successfully applied the pseudoparticle approach to SU(2) Yang-Mills theory. In this work we discuss the inclusion of fermionic fields in the pseudoparticle approach. To test our method, we compute the phase diagram of the 1+1-dimensional Gross-Neveu model in the large-N limit as well as the chiral condensate in the crystal phase.
39889187
Kaon and D meson masses with N_f = 2+1+1 twisted mass lattice QCD
We discuss the computation of the kaon and D meson masses in the N_f = 2+1+1 twisted mass lattice QCD setup, where explicit heavy flavor and parity breaking occurs at finite lattice spacing. We present three methods suitable in this context and verify their consistency.