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Ralf Hofmann

Publications and source records attributed to Ralf Hofmann.

At least 55 records · Page 3Linked to original sources
arXiv2009

Onset of magnetic monopole-antimonopole condensation

We determine the critical strength of the effective electric coupling for the onset of Bose condensation of stable magnetic monopoles and antimonopoles in SU(2) Yang-Mills thermodynamics. Two scenarios are considered: infinitely fast and infinitely slow downward approach of the critical temperature. Our results support the claim that the first lepton family and the weak interactions emerge from pure SU(2) gauge dynamics of scale $\sim 0.5 $MeV.

hep-th↗
arXiv2009

Charged lepton spectra from hot-spot evaporation

Spectra for the emission of charged leptons from evaporating hot-spots of preconfining phase in SU(2) Yang-Mills thermodynamics are computed. Specifically, we consider charged single and dileptons with their spectra being functions of energy and invariant mass, respectively. In the former case, our results relate to narrow and correlated electron and positron peaks measured in supercritical heavy-ion collisions performed at GSI in the 1980ies. In the latter case, we point out how strongly the spectra depend on typical kinematic cuts (CDF analysis of Tevatron Run II data). We also propose a scenario on how muon events of anomalously high multiplicity and large impact-parameter modulus arise in the Tevatron data.

hep-ph↗
arXiv2009

Low-frequency line temperatures of the CMB

Based on SU(2) Yang-Mills thermodynamics we interprete Aracde2's and the results of earlier radio-surveys on low-frequency CMB line temperatures as a phase-boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields of the CMB whose intensity is nulled by that of Planck distributed calibrator photons. The CMB baseline temperature thus is identified with the critical temperature of the deconfining-preconfining transition.

hep-th↗
arXiv2009

Thermal photon dispersion law and modified black-body spectra

Based on the postulate that photon propagation is governed by an SU(2) gauge principle we numerically compute the one-loop dispersion for thermalized photon propagation on the radiatively induced mass shell. Formerly, the dispersion was addressed by assuming $p^2=0$. While this approximation turns out to be excellent for temperatures $\le 2 T_{\tiny{CMB}}$ the exact result exhibits a much faster (power-like) shrinking of the gap in the black-body spectral intensity with rising temperature. Our previous statements on anomalous large-angle CMB temperature-temperature correlations, obtained in the approximation $p^2=0$, remain valid.

hep-th↗
arXiv2009

CMB dipole revisited

We re-evaluate the build-up of a horizon-sized temperature profile of amplitude $δT/T \sim 10^{-3}$ at $z\sim 1$ in light of an improved determination of the black-body anomaly, based on a pure SU(2) Yang-Mills theory, and the correction of a mistake in deriving the evolution equation for $δT$. Our present results for the temperature profiles hardly are distinguishable from those published previously.

hep-th↗
arXiv2008

Scalar Field Theory with a Non-Standard Potential

We study the phase structure of a 4D complex scalar field theory with a potential V(Phi) = | Lambda^3 / Phi - Lambda Phi |^2 at zero and at finite temperature. The model is analyzed by mean field and Monte Carlo methods. At zero temperature the theory falls in the universality class of the 4D Ising model when varying Lambda. The situation is less clear-cut for variations w.r.t. Lambda at large temperatures and variations w.r.t. temperature at a given value of Lambda. We observe temperature independence of the mass of the first excitation.

hep-lat↗
arXiv2008

Center-vortex loops with one selfintersection

We investigate the 2D behavior of one-fold selfintersecting, topologically stabilized center-vortex loops in the confining phase of an SU(2) Yang-Mills theory. This coarse-graining is described by curve-shrinking evolution of center-vortex loops immersed in a flat 2D plane driving the renormalization-group flow of an effective `action'. We observe that the system evolves into a highly ordered state at finite noise level, and we speculate that this feature is connected with 2D planar high $T_c$ superconductivity in $FeAs$ systems.

hep-th↗
arXiv2008

Bursts of low-energy electron-positron pairs in TeV-range collider physics

In this Letter we investigate the possible emission of low-energy electron neutrinos and electron-positron pairs of anomalously large multiplicity in close-to-central $pp$ collisions at LHC. The scenario is based on confining SU(2) Yang-Mills dynamics of Hagedorn temperature $\sim m_e=511 $keV being responsible for the emergence of the lightest lepton family and the weak interactions of the Standard Model. Although cut off by LHC's detectors these electrons-positron bursts would be seen indirectly by a large defect energy and thus an anomalously strong decrease of events with interesting high-energy secondaries for increasing $\sqrt{s}$ . This is because the formation of superconducting (preconfining) SU(2) hot-spots `steals' a large fraction of $\sqrt{s}$ subsequently transferring it to a thermal spectrum of electron neutrinos, electrons, and positrons liberated through evaporation. We thus propose the detection of electrons and positrons of kinetic energy $\sim m_e$ and photons of energy $\sim 2 m_e$.

hep-ph↗
arXiv2008

Evolving center-vortex loops

We consider coarse-graining applied to nonselfintersecting planar center-vortex loops as they emerge in the confining phase of an SU(2) Yang-Mills theory. Well-established properties of planar curve-shrinking predict that a suitably defined, geometric effective action exhibits (mean-field) critical behavior when the conformal limit of circular points is reached. This suggests the existence of an asymptotic mass gap. We demonstrate that the initially sharp mean center-of-mass position in a given ensemble of curves develops a variance under the flow as is the case for a position eigenstate in free-particle quantum mechanics under unitary time evolution. A possible application of these concepts is an approach to high-$T_c$ superconductivity based (a) on the nonlocal nature of the electron (1-fold selfintersecting center-vortex loop) and (b) on planar curve-shrinking flow representing the decrease in thermal noise in a cooling cuprate.

hep-th↗
arXiv2008

A model for the very early Universe

A model with N species of massless fermions interacting via (microscopic) gravitational torsion in de Sitter spacetime is investigated in the limit N->infinity. The U_V(N)*U_A(N) flavor symmetry is broken dynamically irrespective of the (positive) value of the induced four-fermion coupling. This model is equivalent to a theory with free but massive fermions fluctuating about the chiral condensate. When the fermions are integrated out in a way demonstrated long ago by Candelas and Raine, the associated gap equation together with the Friedmann equation predict that the Hubble parameter vanishes. Introducing a matter sector (subject to a finite gauge symmetry) as a source for subsequent cosmology, the neutral Goldstone field acquires mass by the chiral anomaly, resulting in a Planck-scale axion.

hep-th↗
arXiv2008

A model for CMB anisotropies on large angular scales

We investigate the possibility that a low-temperature, low-frequency anomaly in the black-body spectrum, as it emerges when enlarging the Standard Model's gauge-group factor U(1)$_Y$ to SU(2) (Yang-Mills scale $\sim 10^{-4}$ eV), explains the discrepancy between the Local Group's velocity as directly observed and as inferred by assuming a purely kinematic origin of the CMB dipole. This discrepancy determines the kinetic term for temperature fluctuations in our model action. Upon subtracting the dipole contribution this model can then be used to predict the low multipoles with $l\ge 2$ in the CMB temperature-temperature correlation and to reinvestigate the issue of statistical isotropy.

hep-ph↗
arXiv2007

Linear growth of the trace anomaly in Yang-Mills thermodynamics

In the lattice work by Miller [1,2] and in the work by Zwanziger [3] a linear growth of the trace anomaly for high temperatures was found in pure SU(2) and SU(3) Yang-Mills theories. These results show the remarkable property that the corresponding systems are strong interacting even at high temperatures. We show that within an analytical approach to Yang-Mills thermodynamics this linear rise is obtained and is directly connected to the presence of a temperature-dependent ground state, which describes (part of) the nonperturbative nature of the Yang-Mills system. Our predictions are in approximate agreement with [1,2,3]

hep-th↗
arXiv2007

SU(2) Yang-Mills thermodynamics and photon physics

Based on quantitative predictions enabled by a nonperturbative approach to Yang-Mills thermodynamics it is explained why the physics of photon {\sl propagation} is not unlikely rooted in pure SU(2) gauge dynamics.

hep-ph↗
arXiv2007

Yang-Mills thermodynamics at low temperature

For the confining phase of SU(2) Yang-Mills thermodynamics we show that the asymptotic series representing the pressure is Borel summable for negative (unphysical) values of a suitably defined coupling constant. The inverse Borel transform is meromorphic except for a branch cut along the positive-real axis. The physical pressure is precisely nil at vanishing and acquires a small imaginary admixture at small temperature the latter indicating violations of thermal equilibrium (turbulences).

hep-th↗
arXiv2007

Potential for inert adjoint scalar field in SU(2) Yang-Mills thermodynamics

A scalar adjoint field is introduced as a spatial average over (anti)calorons in a thermalized SU(2) Yang-Mills theory. This field is associated with the thermal ground state in the deconfining phase and acts as a background for gauge fields of trivial topology. Without invoking detailed microscopic information we study the properties of the corresponding potential, and we discuss its thermodynamical implications. We also investigate the gluon condensate at finite temperature relating it to the adjoint scalar field.

hep-th↗
arXiv2007

Black-Body Anomaly: Analysis of Temperature Offsets

Based on the postulate that photon propagation is governed by a dynamically broken SU(2) gauge symmetry (scale $\sim 10^{-4} $eV) we make predictions for temperature offsets due to a low-temperature (a few times the present CMB temperature) spectral anomaly at low frequencies. Temperature offsets are extracted from least-square fits of the anomalous black-body spectra to their conventional counterparts. We discuss statistical errors, compare our results with those obtained from calibration data of the FIRAS instrument, and point out that our predicted offsets are screened by experimental errors given the frequency range used by FIRAS to perform their spectral fits. We also make contact with the WMAP observation by blueshifting their frequency bands. Although our results hint towards a strong dynamical component in the CMB dipole and an explanation of low-$l$ suppression it is important in view of its particle-physics implications that the above postulate be verified/falsified by an independent low-temperature black-body precision experiment.

hep-ph↗