Papers by chris korthals altes
Nuclear Physics B, 1992
The interface tension between Z( N) vacua in a hot SU( N) gauge theory (without dynamical fermion... more The interface tension between Z( N) vacua in a hot SU( N) gauge theory (without dynamical fermions) is computed at next to leading order in weak coupling. The Z( N) interface tension is related to the instanton of an effective action, which includes both classical and quantum terms; a general technique for treating consistently the saddle points of such effective actions is developed. Loop integrals which arise in the calculation are evaluated by means of zeta-function techniques. As a byproduct, up to two-loop order we find that the stable vacuum is always equivalent to the trivial one, and so respects charge-conjugation symmetry.
Nuclear Physics B, 1992
The interface tension between Z(N) vacua in a hot SU(N) gauge theory (without dynamical fermions)... more The interface tension between Z(N) vacua in a hot SU(N) gauge theory (without dynamical fermions) is computed at next to leading order in weak coupling. The Z(N) interface tension is related to the instanton of an effective action, which includes both classical and quantum terms; a general technique for treating consistently the saddle points of such effective actions is developed. Loop integrals which arise in the calculation are evaluated by means of zeta function techniques. As a byproduct, up to two loop order we find that the stable vacuum is always equivalent to the trivial one, and so respects charge conjugation symmetry.
Physical Review Letters, 1994
We compute the effective potential for the phase of the Wilson line at high temperature in the st... more We compute the effective potential for the phase of the Wilson line at high temperature in the standard model to one loop order. Besides the trivial vacua, there are metastable states in the direction of $U(1)$ hypercharge. Assuming that the universe starts out in such a metastable state at the Planck scale, it easily persists to the time of the electroweak phase transition, which then proceeds by an unusual mechanism. All remnants of the metastable state evaporate about the time of the $QCD$ phase transition.
Physical Review Letters, 1991
For an SU(N) gauge theory without dynamical fermions, at temperatures above the deconfining trans... more For an SU(N) gauge theory without dynamical fermions, at temperatures above the deconfining transition there are Z(N) degenerate vacua. The interface tension between distinct Z(N) vacua is computed in weak coupling by semiclassical techniques.
Physical Review Letters, 1994
We compute the effective potential for the phase of the Wilson line at high temperature in the st... more We compute the effective potential for the phase of the Wilson line at high temperature in the standard model to one-loop order. Besides the trivial vacua, there are metastable states in the direction of U(1) hypercharge. Assuming that the Universe starts out in such a metastable state at the Planck scale, it easily persists to the time of the electroweak phase transition, which then proceeds by an unusual mechanism. All remnants of the metastable state evaporate about the time of the QCD phase transition.
Physical Review D, 2000
The contribution of quarks to the effective potential for the phase of the Wilson line is compute... more The contribution of quarks to the effective potential for the phase of the Wilson line is computed at nonzero temperature and quark chemical potential to one and two loop order. At zero temperature, regardless of the value of the quark chemical potential, the effective potential for the phase of the Wilson line vanishes. At nonzero temperature, for special values of the phase the free energy of quarks equals that of bosons; at nonzero chemical potential, such quarks can ``Bose condense'', albeit with negative density.
Physics Letters B, 1999
We show that the deconfinement phase transition in the pure Yang-Mills theory can be characterize... more We show that the deconfinement phase transition in the pure Yang-Mills theory can be characterized by the change of behaviour the spatial 't Hooft loop, V (C). In the confining phase V has a perimeter law behaviour V (C) ∝ exp{−mP (C)}, while in the deconfined phase it has the area law behaviour V (C) ∝ exp{−αS(C)}. We show that the area law behaviour of the 't Hooft loop is intimately related to the plasma-like distribution of the color charges in the hot QCD vacuum. We also show that the "dual string tension" α is equal to the"wall tension"of the Z N domain walls previously calculated in [1]. All these properties generalize immediately to other nonabelian theories without fundamental charges, such as supersymmetric Yang Mills. In theories with fundamental charges the 't Hooft loop presumably has the area law behaviour already at zero temperature and therefore is not a good order parameter in the strict sense.
Physical Review D, 2000
. We also point out that the realization of the magnetic symmetry has bearing on the behaviour of... more . We also point out that the realization of the magnetic symmetry has bearing on the behaviour of the spatial Wilson loop. We give a physical argument to the effect that at zero temperature the spatial Wilson loop must have perimeter law behaviour in the symmetric phase but area law behaviour in the spontaneously broken phase. At high temperature the argument does not hold and the restoration of magnetic Z(N) is consistent with area law for the Wilson loop.
Nuclear Physics B, 2003
If SU(N) gauge fields live in a world with a circular extra dimension, coupling there only to adj... more If SU(N) gauge fields live in a world with a circular extra dimension, coupling there only to adjointly charged matter, the system possesses a global Z(N) symmetry. If the radius is small enough such that dimensional reduction takes place, this symmetry is spontaneously broken. It turns out that its fate at high temperatures is not easily decided with straightforward perturbation theory. Utilising non-perturbative lattice simulations, we demonstrate here that the symmetry does get restored at a certain temperature T c , both for a 3+1 and a 4+1 dimensional world (the latter with a finite cutoff). To avoid a cosmological domain wall problem, such models would thus be allowed only if the reheating temperature after inflation is below T c . We also comment on the robustness of this phenomenon with respect to small modifications of the model.
Physics Letters B, 2001
There has been recent interest in new types of topological defects arising in models with compact... more There has been recent interest in new types of topological defects arising in models with compact extra dimensions. We discuss in this context the old statement that if only SU(N) gauge fields and adjoint matter live in the bulk, and the coupling is weak, then the theory possesses a spontaneously broken global Z(N) symmetry, with associated domain wall defects in four dimensions. We discuss the behaviour of this symmetry at high temperatures. We argue that the symmetry gets restored, so that cosmological domain wall production could be used to constrain such models.
TeV size extra dimensions introduce domain walls. Such walls are inconsistent with CMB anisotropi... more TeV size extra dimensions introduce domain walls. Such walls are inconsistent with CMB anisotropies. Either inflationary dynamics washes them out, or the reheating temperature is lower then the temperature at which the walls start forming networks. As the restoration of the symmetry is non-perturbative we have performed 5d lattice simulations which show the occurrence of a cut-off in the fifth dimension as well as symmetry restoration.
Nuclear Physics B, 1994
Constrained effective potentials in hot gauge theory give the probability that a configuration p ... more Constrained effective potentials in hot gauge theory give the probability that a configuration p of the order parameter (Polyakov loop) occurs. They are important in the analysis of surface effects and bubble formation in the plasma. The vector potential appears non-linearly in the loop; in weak coupling the linear term gives rise to the traditional free energy graphs. But the non-linear terms generate insertions of the constrained modes into the free energy graphs, through renormalisations of the Polyakov loop. These insertions are gauge dependent and are necessary to cancel the gauge dependence of the free energy graphs. The latter is shown, through the BRST identities, to have again the form of constrained mode insertions. It also follows, that absolute minima of the potential are at the centergroup values of the loop. We evaluate the two-loop contributions for SU(N) gauge theories, with and without quarks, for the full domain of the N-1 variables.
These lectures start with a brief overview of salient features of the critical region of hot QCD.... more These lectures start with a brief overview of salient features of the critical region of hot QCD. The main emphasis is on the accurate description of static plasma observables by the well-known hierarchy of reduced actions combined with 3D simulations above T\sim 2T_c. A striking pattern emerges, put in perspective by completing the quasi-particle picture
The strong first order nature for more than five colours and the fast drop of the topological sus... more The strong first order nature for more than five colours and the fast drop of the topological susceptibilty at $T_c$ found in simulations of hot quenched QCD are consistent with a quasi-particle picture valid down to the critical temperature. The magnetic quasi-particles will Bose condense in the ground state below $T_c$, and may behave like a dilute Bose gas down to T=0. The model fixes the diluteness as $\sigma/m_M^2$. This is a small number for all temperatures.
These lectures start with a brief overview of salient features of the critical region of hot QCD.... more These lectures start with a brief overview of salient features of the critical region of hot QCD. The main emphasis is on the accurate description of static plasma observables by the well-known hierarchy of reduced actions combined with 3D simulations above T ˜ 2Tc. A striking pattern emerges, put in perspective by completing the quasi-particle picture.
These lectures start with a brief overview of salient features of the critical region of hot QCD.... more These lectures start with a brief overview of salient features of the critical region of hot QCD. The main emphasis is on the accurate description of static plasma observables by the well-known hierarchy of reduced actions combined with 3D simulations above T\sim 2T_c. A striking pattern emerges, put in perspective by completing the quasi-particle picture
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Papers by chris korthals altes