# PASCOS 08

14th International Symposium on Particles, Strings and Cosmology (PASCOS '08)

## Experimental limits on kappa-Minkowski field theories

Friday Jun 06, 2008
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The non-commutative kappa-Minkowski field theory, often tauted as a low-energy candidate for the quantum description of gravity, operates on a spacetime which possesses a modified Lorentz invariance, and as such can be probed in high-precision low-energy experiments. We study the first order corrections in kappa to the Standard Model, and show that they typically induce a coupling of nuclear spin to an external background at low energies.

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## A covariant entropy bound conjecture on dynamical horizon

Friday Jun 06, 2008
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After introduction and motivation, I will present a covariant entropy bound conjecture on dynamical horizon in a general sense. Then I will show its validity in black hole case and cosmological context. Especially its power in constraint on the cosmological constant is addressed. I will end up with the outlook of this conjecture.

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## Flavon Inflation

Friday Jun 06, 2008
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A new class of particle physics models of inflation is presented which is based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show

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## Probing the primordial helium abundance and the effective number of neutrino species with CMB

Friday Jun 06, 2008
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We point out that light scalar fields with symmetries generically generate non-Gaussianity in the density fluctuations. Our observation makes the presence of the non-Gaussianity ubiquitous. When the inflationary scale and the properties of the scalar fields satisfy a certain relation, the non-Gaussianity becomes large enough to be observed by the ongoing and planned observations. We name such a particle responsible for a large non-Gaussianity as an \'ungaussiton\', and give explicit examples to realize the ungaussiton mechanism.

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## CDM / LHC: How Robust is the Connection?

Friday Jun 06, 2008
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One of the most compelling hints for physics beyond the standard model is the cosmological observation that nearly a quarter of our universe consists of cold dark matter. In the next few years, LHC shows the promise of producing these elusive particles and possibly measuring their microscopic properties. This will be challenging, per se, and using LHC observations to reconstruct a complete theory of cosmological dark matter could prove quite challenging. In this talk I will discuss the prospects and many challenges facing such a program.

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## Gravitational Bursts from Unstable Cosmic Strings

Friday Jun 06, 2008

We compute the GW signature of a meta-stable cosmic string network. Such networks arise in a large class of brane inflation models.

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## Stochastic Inflation and Replica Field Theory

Friday Jun 06, 2008
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We formulate a general replica field-theoretic framework for stochastic inflation in which a manifestation of dimensional reduction is found. The scale above which the latter becomes dominant is explicitly calculated. It is found that for a wide class of stochastic systems considerable changes of the spectral index inevitably occur on super-horizon scales. We work out an explicit relation between the noise correlator and the non-Gaussianity parameter $f_{NL}$, which thus can effectively be generated entirely by quantum fluctuations.

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## Beyond the big bang in Loop Quantum Cosmology

Friday Jun 06, 2008
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Loop quantum cosmology is a non-perturbative canonical quantization of simple cosmological models based on loop quantum gravity. In recent years, a greater control on the underlying quantum theory has revealed a picture where the big bang is replaced by a quantum bounce at Planck scale. The evolution across the bounce is unitary and non-singular without a need of choice of exotic potential or matter.

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## Bubbles of Nothing and Violations of the Energy Conditions in AdS-CFT

Friday Jun 06, 2008
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I describe a variety of bubbles of nothing which do not require a Kaluza-Klein circle but instead may be found in asymptotically flat or AdS spaces without any identifications.  There are many such bubbles which expand outwards and threaten to destabilize spacetimes with more than four dimensions.   In the AdS case, one can show there are both bubbles and topologically trivial smooth states which violate all of the energy bounds, both classical and quantum, in the corresponding gauge theory.

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## The Higgs Self-Coupling as a Probe of the Electroweak Phase Transition

Friday Jun 06, 2008
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We argue that, within a broad class of extensions of the Standard Model, there is a tight corellation between the dynamics of the electroweak phase transition and the cubic self-coupling of the Higgs boson: Models which exhibit a strong first-order electroweak phase transition predict a large deviation of the Higgs self-coupling from the Standard Model prediction, as long as no accidental cancellations occur. Order-one deviations are typical.

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## RECENT PUBLIC LECTURE

### Molly Shoichet: Engineering Change in Medicine

Speaker: Molly Shoichet