Particle theory

Abstract:

We present an update of the Binoth Les Houches Accord (BLHA) to standardise the interface between Monte Carlo programs and codes providing one-loop matrix elements. © 2013 Elsevier B.V. All rights reserved.

Abstract:

The Precision IceCube Next Generation Upgrade (PINGU) is a proposed low-energy in-fill array of the IceCube Neutrino Observatory. Leveraging technology proven with IceCube, PINGU will feature the world's largest effective volume for neutrinos at an energy threshold of a few GeV, improving the sensitivity to several aspects of neutrino oscillation physics at modest cost. With its unprecedented statistical sample of low-energy atmospheric neutrinos, PINGU will have highly competitive sensitivity to $\nu_{\mu}$ disappearance, the $\theta_{23}$ octant, and maximal mixing, will make the world's best $\nu_{\tau}$ appearance measurement, allowing a unique probe of the unitarity of the PMNS mixing matrix, and will be able to distinguish the neutrino mass ordering at $3\sigma$ significance with less than 4 years of data. PINGU can also extend the indirect search for solar WIMP dark matter complimentary to the on-going and planned direct dark matter experiments. At the lower end of the energy range, PINGU may use neutrino tomography to directly probe the composition of the Earth's core. With its increased module density, PINGU will improve IceCube's sensitivity to galactic supernova neutrino bursts and enable it to extract the neutrino energy spectral shape.

Abstract:

A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, $\eta$, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range $\eta = (5.7-6.7)\times 10^{-10}$ at 95% CL (corresponding to a cosmological baryon density $\Omega_B h^2 = 0.021 - 0.025$). The D and He-4 abundances, when combined with the CMB determination of $\eta$, provide the bound $N_\nu=3.28 \pm 0.28$ on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

Abstract:

Compactifications of heterotic theories on smooth Calabi-Yau manifolds remain one of the most promising approaches to string phenomenology. In two previous papers, arXiv:1106.4804 and arXiv:1202.1757, large classes of such vacua were constructed, using sums of line bundles over complete intersection Calabi-Yau manifolds in products of projective spaces that admit smooth quotients by finite groups. A total of 1012 different vector bundles were investigated which led to 202 SU(5) Grand Unified Theory (GUT) models. With the addition of Wilson lines, these in turn led, by a conservative counting, to 2122 heterotic standard models. In the present paper, we extend the scope of this programme and perform an exhaustive scan over the same class of models. A total of 1040 vector bundles are analysed leading to 35, 000 SU(5) GUT models. All of these compactifications have the right field content to induce low-energy models with the matter spectrum of the supersymmetric standard model, with no exotics of any kind. The detailed analysis of the resulting vast number of heterotic standard models is a substantial and ongoing task in computational algebraic geometry. © 2014 SISSA.