Search arXiv⌕ Search

arXiv · nucl-th/0408015

Confinement, DCSB, Bound States, and the Quark-Gluon Vertex

Abstract

Aspects of the dressed-quark-gluon vertex and their role in the gap and Bethe-Salpeter equations are briefly surveyed using an intuitive model. The model allows one to elucidate why a linear extrapolation to the chiral limit of extant lattice data on the dressed-quark mass-function overestimates this function and hence the value of the vacuum quark condensate. The diagrammatic content of the vertex described is explicitly enumerable. This property is essential to the symmetry preserving study of bound state properties. It facilitates a realistic analysis of vector and pseudoscalar meson masses, and also allows the accuracy of standard truncations to be gauged. The splitting between vector and pseudoscalar meson masses is observed to vanish as the current-quark mass increases. That argues for the mass of the pseudoscalar partner of the Upsilon(1S) to be above 9.4GeV. Moreover, in this limit the rainbow-ladder truncation provides an increasingly accurate estimate of a bound state's mass.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A. Holl, A. Krassnigg, C. D. Roberts. 2004-08-05. Confinement, DCSB, Bound States, and the Quark-Gluon Vertex. https://doi.org/10.1016/j.nuclphysbps.2004.12.009

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Intertwined quantum phase transitions in the even-even $^{90-100}$Sr isotopes

The even-even $^{90-100}$Sr isotopes are identified as a region of intertwined quantum phase transitions (IQPTs). In this scenario, a quantum phase transition involving the crossing of normal and intruder configurations is accompanied by a shape evolution within the intruder configuration. Using the interacting boson model with configuration mixing (IBM-CM), its is shown that the strontium chain exhibits the IQPT scenario, where the intruder configuration evolves from a near-spherical structure in $^{90\text{--}96}$Sr to a deformed one in $^{98,100}$Sr, while the normal and intruder configurations cross between $^{96}$Sr and $^{98}$Sr. As a result, the ground state changes abruptly from a weakly collective normal configuration to a deformed intruder configuration. Evidence for this scenario is provided by a detailed comparison with experimental excitation energies, isotope shifts, and monopole $E0$ transition strengths, together with the configuration and $n_d$ decompositions of the calculated wave functions. The results place the strontium isotopes alongside the neighboring zirconium chain as a realization of IQPTs in the intricate $A\approx100$ region.

nucl-th↗

Imprints of the nuclear liquid-gas phase transition on net-baryon number fluctuations

We investigate net-baryon number fluctuations in the high-density, low-temperature region of the QCD phase diagram using the parity-doublet model (PDM) under the mean-field approximation. We compute the fluctuation ratios up to sixth order around the nuclear liquid-gas (LG) phase transition, where the high-order ratios are particularly sensitive. To connect the results with heavy-ion experiments, we test several different scenarios of chemical freeze-out. We find that near the LG transition the extracted fluctuations depend strongly on the choice of freeze-out curve. We self-consistently determine four freeze-out points from preliminary results of the STAR Collaboration. Comparing the experimental data with the PDM results along these four points, we find that the model describes the low energy ($\sqrt{s_{NN}}\lesssim$ 4 GeV) data well. This suggests that nucleon interactions and the LG phase transition may contribute significantly to the fluctuations in low energy heavy-ion collisions.

nucl-th↗

Strangeness Production in Heavy-Ion Collisions: Color Ropes or Hydrodynamic Evolution?

We investigate strangeness production and transverse dynamics in heavy-ion collisions at $\sqrt{s_{\mathrm{NN}}}\approx 2.5-20~\mathrm{GeV}$ using the transport approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons), its extension with rope hadronization, and the SMASH+vHLLE hybrid approach. Results from the Pythia-based heavy-ion model Angantyr, with and without rope hadronization, are included for comparison. We study midrapidity particle yields and average transverse masses as functions of the number of wounded nucleons, as well as their energy dependence. For the $K^+/π^+$ ratio, SMASH+vHLLE overpredicts strangeness production at low energies but describes the higher-energy behavior reasonably well. SMASH+Ropes reproduces the ratio up to $\sqrt{s_{\mathrm{NN}}}\sim 10~\mathrm{GeV}$ but does not capture the turnover at higher energies. In contrast, the transverse-mass observables favor the hybrid approach, while the non-thermal models considered here do not generate sufficient collective transverse expansion. These results show that strangeness enhancement alone does not uniquely distinguish microscopic string interactions from a locally equilibrated medium. Simultaneously constraining strangeness production and transverse dynamics is therefore essential for disentangling thermal and non-thermal mechanisms in heavy-ion collisions.

nucl-th↗