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P. Petreczky

Publications and source records attributed to P. Petreczky.

At least 127 records · Page 7Linked to original sources
arXiv2003

Infinite temperature limit of meson spectral functions calculated on the lattice

We analyze the cut-off dependence of mesonic spectral functions calculated at finite temperature on Euclidean lattices with finite temporal extent. In the infinite temperature limit we present analytic results for lattice spectral functions calculated with standard Wilson fermions as well as a truncated perfect action. We explicitly determine the influence of `Wilson doublers' on the high momentum structure of the mesonic spectral functions and show that this cut-off effect is strongly suppressed when using an improved fermion action.

hep-lat↗
arXiv2003

Renormalized quark-anti-quark free energy

We present results on the renormalized quark-anti-quark free energy in SU(3) gauge theory at finite temperatures. We discuss results for the singlet, octet and colour averaged free energies and comment on thermal relations which allow to extract separately the potential energy and entropy from the free energy.

hep-lat↗
arXiv2002

Heavy Quark Free Energies and Screening in SU(2) Gauge Theory

We investigate the singlet, triplet and colour average heavy quark free energies in SU(2) pure gauge theory at various temperatures T. We focus on the long distance behaviour of the free energies, studying in particular the temperature dependence of the string tension and the screening masses. The results are qualitatively similar to the SU(3) scenario, except near the critical temperature Tc of the deconfining transition. Finally we test a recently proposed method to renormalize the Polyakov loop.

hep-lat↗
arXiv2002

Heavy Quark Anti-Quark Free Energy and the Renormalized Polyakov Loop

We calculate the colour averaged and colour singlet free energies of static quark anti-quark sources placed in a thermal gluonic heat bath. We discuss the renormalization of these free energies using the short distance properties of the zero temperature heavy quark potential. This leads to the definition of the renormalized Polyakov loop as an order parameter for the deconfinement phase transition of the SU(3) gauge theory which is well behaved in the continuum limit.

hep-lat↗
arXiv2002

Parton Percolation and J/Psi Suppression

The geometric clustering of partons in the transverse plane of nuclear collisions leads for increasing A or sqrt(s) to percolation. In the resulting condensate, the partons are deconfined but not yet in thermal equilibrium. We discuss quarkonium dissociation in this precursor of the quark-gluon plasma, with an onset of dissociation when the saturation scale of the parton condensate reaches that of the given quarkonium state.

hep-ph↗
arXiv2002

A Lattice Calculation of Thermal Dilepton Rates

Using clover improved Wilson fermions we calculate thermal vector meson correlation functions above the deconfinement phase transition of quenched QCD. At temperatures 1.5 Tc and 3Tc they are found to differ by less than 15% from that of a freely propagating quark anti-quark pair. This puts severe constraints on the dilepton production rate and in particular rules out a strong divergence of the dilepton rate at low energies. The vector spectral function, which has been reconstructed using the Maximum Entropy Method, yields an enhancement of the dilepton rate over the Born rate of at most a factor two in the energy interval 4 < E/T < 8 and suggests that the spectrum is cut-off at low energies by a thermal mass threshold of about (2-3)T.

hep-lat↗
arXiv2002

Quarkonium Suppression

I discuss quarkonium suppression in equilibriated strongly interacting matter. After a brief review of basic features of quarkonium production I discuss the application of recent lattice data on the heavy quark potential to the problem of quarkonium dissociation as well as the problem of direct lattice determination of quarkonium properties in finite temperature lattice QCD.

hep-ph↗
arXiv2001

Sequential Quarkonium Suppression

We use recent lattice data on the heavy quark potential in order to determine the dissociation temperatures of different quarkonium states in hot strongly interacting matter. Our analysis shows in particular that certain quarkonium states dissociate below the deconfinement point.

hep-ph↗
arXiv2001

Meson Spectral Functions at finite Temperature

The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above $T_c$. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size $(24-64)^3 \times 16$. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature.

hep-lat↗
arXiv2001

An new order parameter with renormalized Polyakov loops

It is well established that physical quantities like the heavy quark potentials get temperature independent at sufficiently short distances. As a first application of this feature we suggest a new order parameter for the confinement/deconfinement phase transition. Our investigations are based on recent lattice studies.

hep-lat↗
arXiv2001

Short distance physics with heavy quark potentials

We present lattice studies of heavy quark potentials in the quenched approximation of QCD at finite temperatures. Both, the color singlet and color averaged potentials are calculated. While the potentials are well known at large distances, we give a detailed analysis of their short distance behavior (from 0.015 fm to 1 fm) near the critical temperature. At these distances we expect that the T-dependent potentials go over into the zero temperature potential. Indeed, we find evidences that the temperature influence gets suppressed and the potentials starts to become a unique function of the underlying distance scale. We use this feature to normalize the heavy quark potentials at short distances and extract the free energy of the quark system in a gluonic heat bath.

hep-lat↗
arXiv2001

Quarkonium Feed-Down and Sequential Suppression

About 40-50 % of the quarkonium ground states J/psi(1S) and Upsilon(1S) produced in hadronic collisions originate from the decay of higher excitations. In a hot medium, these higher states are dissociated at lower temperatures than the more tightly bound ground states, leading to a sequential suppression pattern. Using new finite temperature lattice results, we specify the in-medium potential between heavy quarks and determine the dissociation points of different quarkonium states. On the basis of recent CDF data on bottomonium production, we then obtain first predictions for sequential Upsilon suppression in nuclear collisions.

hep-ph↗
arXiv2001

Propagators and Dimensional Reduction of Hot SU(2) Gauge Theory

We investigate the large distance behavior of the electric and magnetic propagators of hot SU(2) gauge theory in different gauges using lattice simulations of the full 4d theory and the effective, dimensionally reduced 3d theory. Comparison of the 3d and 4d propagators suggests that dimensional reduction works surprisingly well down to the temperature T=2 T_c. Within statistical uncertainty the electric screening mass is found to be gauge independent. The magnetic propagator, on the other hand, exhibits a complicated gauge dependent structure at low momentum.

hep-lat↗
arXiv2001

String Breaking and Quarkonium Dissociation at Finite Temperatures

Recent lattice studies of string breaking in QCD with dynamical quarks determine the in-medium temperature dependence of the heavy quark potential. Comparing this to the binding energies of different quarkonium states, we check if these can decay into open charm/beauty in a confined hadronic medium. Our studies indicate in particular that the chi_c and the psi dissociate into open charm below the deconfinement point.

hep-ph↗
arXiv2000

Effective Z(2) Spin Models of Deconfinement and Percolation in SU(2) Gauge Theory

Effective theories are helpful tools to gain an intuitive insight into phenomena governed by complex laws. In this work we show by means of Monte Carlo simulations that Z(2) spin models with only spin-spin interactions approximate rather well the critical behavior of SU(2) gauge theory at finite temperature. These models are then used to formulate an effective description of Polyakov loop percolation, which is shown to reproduce the thermal critical behaviour of SU(2) gauge theory.

hep-lat↗
arXiv2000

Magnetic Screening in Hot Non-Abelian Gauge Theory

We analyze the large distance and low-momentum behavior of the magnetic gluon propagator of the SU(2) gauge theory at finite temperature. Lattice calculations within the 4-dimensional as well as the effective, dimensionally reduced 3-dimensional gauge theories in generalized Landau gauges and MAG show that the magnetic propagator is strongly infrared suppressed in Landau gauges but stays large and finite in MAG. Despite these differences in the low-momentum behavior of the propagator calculated in different gauges the magnetic fields are exponentially screened in all gauges considered. From the propagator calculated in maximally Abelian gauge we find for the screening mass, m_M = (1.48 +/- 0.17) T at T=2 T_c.

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