Ulrik adds “There were many reasons that I felt compelled to apply for this position at CP3. I have through the studies at master level been exposed to some very exciting physics. The position allows me to get involved in research at the high-energy frontier and this is particularly interesting in a time where the Large Hadron Collider operates at energies higher than ever. I intent in the Ph.D. project to focus on orthogonal technicolor, gauge theories with spinorial representations, technicolor theories under extreme conditions and their equations of state.”

Jakob will focus his Ph.D. studies on “Strong dynamics for cosmology” dividing his effort between two subprojects on respectively, composite dark matter and dynamical origin of inflation.

An interesting paper Ruling Out Multi-Order Interference in Quantum Mechanics recently submitted to the online arXiv (1007.4193 [hep-lat]) will be briefly presented for further discussion.

We study the high-energy limit of tree-level string production amplitudes from decaying D-branes in bosonic string theory, interpreting the vertex operators as external charges interacting with a Coulomb gas corresponding to the rolling tachyon background, and performing an electrostatic analysis. In particular, we consider two open string – one closed string amplitudes and four open string amplitudes, and calculate explicit formulas for the leading exponential behavior.

You can use this as an entry point for all the different interesting articles within our area.

The grant will be used to setup a supercomputer based on nVidia Tesla “Fermi” GPU cores connected through Infiniband. Compared to more traditional homogeneous CPU based supercomputers,  GPU systems deliver a factor 10-20 better effciency in terms of Flops/Watt at only 1/10th of the cost.

The supercomputer will be used to investigate the two main candidates for a more fundamental theory of nature at the Fermi scale: Technicolor and Supersymmetry. Both models for new physics play a key role for understanding the results from the Large Hadron Collider LHC at CERN which has started taking data in April 2010.
Using numerical simulations based on Lattice Gauge Theory, the supercomputer will be used as a reliable way to investigate the non-perturbative properties of both supersymmetric theories and strongly coupled Technicolor extensions of the standard model.

Our peculiar velocity with respect to the CMB rest frame is known to induce a large dipole in the CMB. However, the motion of an observer has also the effect of distorting the anisotropies at all scales, as shown by Challinor and Van Leeuwen (2002), due to aberration and Doppler effects. We propose to measure independently our local motion by using off-diagonal two-point correlation functions for high multipoles. We study the observability of the signal for temperature and polarization anisotropies. We point out that Planck can measure the velocity β with an error of about 10%-20% and the direction with an error of about 5-10 degrees. This method constitutes a cross-check, which can be useful to verify that our CMB dipole is due mainly to our velocity or to disentangle the velocity from other possible intrinsic sources. Although in this paper we focus on our peculiar velocity, a similar effect would result also from other intrinsic vectorial distortion of the CMB which would induce a dipolar lensing. Measuring the off-diagonal correlation terms is therefore a test for a preferred direction on the CMB sky.

We extend the results of [arXiv:1006.0207 [hep-lat]] by computing the S-parameter at two loops in the perturbative region of the conformal window. Consistently using the expression for the location of the infra-red fixed point at the two-loop order we express the S-parameter in terms of the number of flavors, colors and matter representation. We show that S, normalized to the number of flavors, increases as we decrease the number of flavors and gives a direct measure of the anomalous dimension of the mass of the fermions. Our findings support the conjecture presented in [arXiv:1006.0207 [hep-lat]] according to which the normalized value of the S-parameter at the upper end of the conformal window constitutes the lower bound across the entire phase diagram for the given underlying asymptotically free gauge theory. We also show that the non-trivial dependence on the number of flavors merges naturally with the non-pertrubative estimate of the S-parameter close to the lower end of the conformal window obtained using gauge duality [arXiv:1007.0254 [hep-ph]]. Our results are natural benchmarks for lattice computations of the S-parameter for vector-like gauge theories and together with the lower bound constitute important constraints on models of dynamical electroweak symmetry breaking and unparticle physics.