Relational particle mechanics are theories of relative angles and relative (ratios of) separations only. These bear a number of resemblances to the geometrodynamical formulation of general relativity and as such are useful analogues for at least some approaches to the notorious problem of time in quantum gravity. I have recently provided a fairly complete study of the configuration spaces of these theories in spatial dimension 1 and 2, am subsequently studying the redused forms of these theories at the quantum level, and this shall provide a number of useful examples for the conceptual discussion of various problem of time strategies.

Strong gauge dynamics can be given a holographic description in terms of a warped extra dimension. In particular, Randall-Sundrum models with bulk fields are dual to Standard Model partial compositeness.  We identify a holographic basis of 4D fields that allows for a quantitative description of the elementary/composite mixing in these theories.

A conceptual framework is proposed for understanding the relationship between observables and operators in mechanics.  We claim that the transformations generated by the objective properties of a physical system must be strictly interpreted as gauge transformations.  It will be shown that this postulate cannot be consistently implemented in the framework of classical mechanics.  We argue that the uncertainty principle is a consequence of the mutual intertwining between objective properties and gauge-dependant properties.  Hence, in classical mechanics gauge-dependant properties are wrongly considered objective.  It follows that the quantum description of objective physical states is not incomplete, but rather that the classical notion is overdetermined.

After a brief motivation for studying 3d gravity, a review of Strominger argument will be given, showing that 3d quantum gravity with negative cosmological constant is a conformal field theory. Classical phase space tools will be introduced to develop semi-classical analyses of gravity with zero cosmological constant, and, with negative cosmological constant and closed timelike curves.

Marina Cortes
Is the dynamics of tracking Dark Energy detectable? (astro-ph/0709.0526)

We highlight the unexpected impact of nucleosynthesis on the detectability of tracking quintessence dynamics at late times, showing that dynamics may be invisible until Stage-IV dark energy experiments (DUNE, JDEM, LSST, SKA). Nucleosynthesis forces |w&#8242;(0)| <0.2 for the models we consider and strongly limits potential deviations from _LCDM .Surprisingly, the standard CPL parametrisation, w(z) = w0 +waz/(1+z), cannot match the nucleosynthesis bound for minimally coupled tracking scalar fields. Given that such models are arguably the best-motivated alternatives to a cosmological constant these results may significantly impact future cosmological survey design and imply that dark energy may be dynamical even if we do not detect any dynamics in the next decade."

The spacetime or histories approach is a whole attitude to quantum mechanics in which histories are fundamental rather than states. In this talk we will review a suggested dynamics and a suggested interpretation in this framework, phrasing the dynamics of stochastic collapse models in the histories language then proceeding to explore a new realist interpretation suggested by Rafael Sorkin and examining its perspective on the Kochen-Specker result.

In this talk we propose a Reduced Phase Space Quantization approach to Loop Quantum Gravity. The idea is to combine the relational formalism introduced by Rovelli in the extended form developed by Dittrich and the Brown-Kuchar-Mechanism. The relational formalism can be used to construct gauge invariant observables for constrained systems such as General Relativity, while the Brown-Kuchar-Mechanism is a particular application of the relational formalism in which pressureless dust is taken as the clock of the system. By combining these two we obtain a framework in which the constraints of General Relativity deparametrize such that the algebra of observables has a very simple structure and furthermore we obtain a so called physical Hamiltonian generating the evolution of those observables. The quantization of the reduced phase space and the physical Hamiltonian can be obtained by using standard LQG techniques and gives a direct access to the physical Hilbert space, which is much harder to achieve in the standard Dirac quantization.
Additionally we will analyze the quantization in the Algebraic Quantum Gravity context and discuss the differences that occur. Finally we will present recent results where this framework has been applied to cosmological perturbation theory.

Alternative gauge choices for worldsheet supersymmetry can elucidate dynamical phenomena obscured in the usual superconformal guage.  In the particular example of the tachyonic E_8 heterotic string, we use a judicious gauge choice to show that the process of closed-string tachyon condensation can be understood in terms of a worldsheet super-Higgs effect.  The worldsheet gravitino assimilates the goldstino and becomes a dynamical propagating field.  Conformal, but not superconformal, invariance is maintained throughout.

Jukka Kiukas
Moment Problem and Homodyne Detection

We describe the measurement statistics of the balanced homodyne detection scheme in terms of the moment operators of the associated positive operator measures. In particular, we give a mathematically rigorous proof for the fact that the high amplitude limit in the local oscillator leads to a measurement of a rotated quadrature operator of the signal _eld. Using these results, we also show that each covariant phase space observable can be measured with the eight-port homodyne detector.

Johannes Kofler
Quantum, classical & coarse-grained measurements

The descriptions of the quantum realm and the macroscopic classical world differ significantly not only in their mathematical formulations but also in their foundational concepts and philosophical consequences. When and how physical systems stop to behave quantumly and begin to behave classically is still heavily debated in the physics community and subject to theoretical and experimental research.

Conceptually different from already existing models, we have developed a novel theoretical approach to understand this transition from the quantum to a macrorealistic world. It neither needs to refer to the environment of a system (decoherence) nor to change the quantum laws itself (collapse models) but puts the stress on the limits of observability of quantum phenomena due to our measurement apparatuses.

First, we demonstrated that for unrestricted measurement accuracy a system’s time evolution cannot be described classically, not even if it is arbitrarily large and macroscopic. Under realistic conditions in every-day life, however, we are only able to perform coarse-grained measurements and do not resolve individual quantum levels of the macroscopic system. As we could show, it is this mere restriction to fuzzy measurements which is sufficient to see the natural emergence of macroscopic realism and even the classical Newtonian laws out of the full quantum laws: the system’s time evolution governed by the Schrödinger equation and the state projection induced by measurements. This resolves the apparent impossibility of how classical realism and deterministic laws can emerge out of fundamentally random quantum events.

We find the sufficient condition for these classical evolutions for isolated systems under coarse-grained measurements. Then we demonstrate that nevertheless there exist ”non-classical” Hamiltonians which are in conflict with macroscopic realism. Thus, though at every instant of time the quantum state appears as a classical mixture, its time evolution cannot be understood classically. We argue why such Hamiltonians are unlikely to be realized in nature.

While Calabi-Yau compactifications of string theory are mathematically elegant, they typically result in many massless scalars in the low-energy, four-dimensional theory.  Thus, it is interesting to consider non-Kahler compactifications in the hopes of deriving more phenomenologically interesting models.  These models have received little attention in the heterotic theory owing to their mathematical complexity, however in recent work we have found a potential way to derive interesting features of such compactifications using gauged linear sigma models.

There has been much interest, in the past few years, in the kappa-Poincare'/kappa-Minkowski framework as a possible scenario for a deformation of Poincare' symmetries at Planck scale. I will show how it is possible to give a physical characterization of the concept of quantum symmetries described by a nontrivial Hopf algebra. In particular, I will discuss the generalization of the Noether analysis for a scalar field in  kappa-Minkowski space-time and derive conserved charges associated with each generator of the kappa-Poincare' Hopf-algebra. Then I will report on a recent proposal for the quantization of a scalar field enjoying kappa-Poincare' symmetries, which consists in a construction of the Fock-space of the theory consistent with the structure of deformed symmetries. Finally I will comment on possible applications of deformed symmetries scenarios in cosmology.

Quantum fields in the Minkowski vacuum are entangled with respect to local field modes.  This entanglement can be swapped to spatially separated quantum systems using standard local couplings.  A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe.  Using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case.The two universes can thus be distinguished by their entangling power.

Akimasa Miyake
Phase transition of computational power of measurement-based quantum computer

One of the most significant questions in quantum information is about the origin of the computational power of the quantum computer; namely, from which feature of quantum mechanics and how does the quantum computer obtain its superior computational potential compared with the classical computer?

In my talk, I address this open question more concisely through the study of measurement-based quantum computer, in which all the quantum resource is attributed to entanglement since computation is carried through its consumption by local measurements. I also show a simple model of the phase transition of quantum computer occurring at some threshold, below which the quantum computer comes to allow an efficient classical simulation in accordance with an exponential drop in the amount of entanglement.

Leonardo Modesto
Gravitons and black holes in loop quantum gravity

In the first part of the talk we introduce a technique to compute large scale correlations in LQG and spinfoam models. Using this formalism we calculate some components of the graviton propagator and of the n-points function.

In the second part we apply the ideas suggested by LQG to the black hole interior. The result of the quantum analysis is that the classical singularity disappears in loop quantum gravity. Solving the semiclassical Einstein equation of motion we obtain a metric regular and singularity free in  contrast to the classical one. By using the new metric we calculate the Hawking temperature, entropy and we study the mass evaporation process.

David E Morrissey
Cosmic Strings from Supersymmetric Flat Directions

Cosmic strings are non-trivial configurations of scalar (and vector) fields that are stable on account of a topological conservation law.
They can be formed in the early universe as it cools after the Big Bang.The scalar fields required to form cosmic strings arise naturally if Nature is supersymmetric at high energies.  A common feature of supersymmetric theories are directions in the scalar potential that are extremely flat.  Combining these two ingredients, the cosmic strings associated with supersymmetric flat directions are qualitatively different from ordinary cosmic strings. 

In particular, flat-direction strings have very stable higher-winding modes, and are very wide relative to the scale of their energy density.

These novel features have important implications for the formation and evolution of a network of flat-direction cosmic strings in the early universe.  They also affect the observational signatures of the strings, which include gravity waves, dark matter, and modifications to the nuclear abundances and the blackbody spectrum of the microwave background radiation.

I will talk about meta-stable supersymmetry breaking vacua in SQCD and Seiberg-Witten Theories. Also I will mention their string theory embeddings

Tomasz Paterek
A quantum view on locality, realism and information.

In this talk, I will talk about recent developments in studying strongly coupled gauge theory using the gauge/gravity duality in string theory. In particular, the inclusion of fundamental degrees of freedom and finite chemical potential is reviewed. As an example, I will discuss the results from analyzing the gravitational dual of a none-supersymmetric gauge theory at low temperature and finite baryon chemical potential.

With the discovery of many new satellite galaxies, in recent years our understanding of the Milky Way environment has undergone a dramatic transformation.  I will discuss what these discoveries are telling us about galaxy formation and the nature of dark matter itself. Issues I will focus on include: identifying the least luminous dark matter halo in the Universe, distinguishing between warm and cold dark matter, and indirect dark matter detection.

We demonstrate a number of effective field theory constructions developed to capture the effects of new physics on the Higgs sector of the standard  model. We demonstrate that as the self couplings of the Higgs could be significantly effected by new physics, novel phenomenology such as a two Higgs bound state (Higgsium) may be possible. 

We also demonstrate that the effects of new physics  on the Higgs fermion couplings,  and thus the Higgs width, could be significant.  We show that it is possible this could happen while the new physics cannot be directly detected at LHC. This could lead to an early Higgs discovery  or a missing Higgs  in the first 100 fb^(-1) of data at LHC. 

Warped backgrounds in string theory are useful tools for building phenomenological models of early universe cosmology and particle physics.  In particular, warped backgrounds play an important role in constructing viable models of brane inflation and can help explain the presence of hierarchies in particle physics.  One interesting feature of warped models is that subtle differences in the warped geometry can lead to significant differences in observational signatures in the CMB and at the LHC that can be used to distingiush different models.  In this talk, I will discuss recent work in distinguishing different warped geometries through CMB and LHC observations.

Korneel van den Broek
(almost) Stable Islands in the Landscape

We will consider stability in the string theory landscape. A survey over several classes of flux vacua with different characteristics indicates that the vast majority of flux vacua with small cosmological constant are unstable to rapid decay to a big crunch. Only vacua with large compactification radius or (approximately) supersymmetric configurations turn out to be long lived. We will speculate that regions of the landscape with approximate R-symmetry, while rare, might be cosmological attractors.