M-brane Models from Non-Abelian Gerbes

We make the observation that M-brane models defined in terms of 3-algebras can be interpreted as higher gauge theories involving Lie 2-groups. Such gauge theories arise in particular in the description of non-abelian gerbes. This observation allows us to put M2- and M5-brane models on equal footing, at least as far as the gauge structure is concerned. Furthermore, it provides a useful framework for various generalizations; in particular, it leads to a fully supersymmetric generalization of a previously proposed set of tensor multiplet equations.Comment: 17 pages, v2: new SUSY models, version published in JHE

Self-dual String and Higher Instanton Solutions

We present and discuss explicit solutions to the non-abelian self-dual string equation as well as to the non-abelian self-duality equation in six dimensions. These solutions are generalizations of the 't Hooft-Polyakov monopole and the BPST instanton to higher gauge theory. We expect that these solutions are relevant to the effective description of M2- and M5-branes.Comment: 23 pages, 2 figures, v2 presentation improved, minor errors corrected, new subsection with comment

Primordial black holes in non-Gaussian regimes

Primordial black holes (PBHs) can form in the early Universe from the collapse of rare, large density fluctuations. They have never been observed, but this fact is enough to constrain the amplitude of fluctuations on very small scales which cannot be otherwise probed. Because PBHs form only in very rare large fluctuations, the number of PBHs formed is extremely sensitive to changes in the shape of the tail of the fluctuation distribution - which depends on the amount of non-Gaussianity present. We first study how local non-Gaussianity of arbitrary size up to fifth order affects the abundance and constraints from PBHs, finding that they depend strongly on even small amounts of non-Gaussianity and the upper bound on the allowed amplitude of the power spectrum can vary by several orders of magnitude. The sign of the non-linearity parameters (f_{NL}, g_{NL}, etc) are particularly important. We also study the abundance and constraints from PBHs in the curvaton scenario, in which case the complete non-linear probability distribution is known, and find that truncating to any given order (i.e. to order f_{NL} or g_{NL}, etc) does not give accurate results

Underlying event sensitive observables in Drell-Yan production using GENEVA

We present an extension of the GENEVA Monte Carlo framework to include multiple parton interactions (MPI) provided by PYTHIA8. This allows us to obtain predictions for underlying-event sensitive measurements in Drell-Yan production, in conjunction with GENEVA's fully-differential NNLO calculation, NNLL' resummation for the 0-jet resolution variable (beam thrust), and NLL resummation for the 1-jet resolution variable. We describe the interface with the parton shower algorithm and MPI model of PYTHIA8, which preserves both the precision of partonic N-jet cross sections in GENEVA as well as the shower accuracy and good description of soft hadronic physics of PYTHIA8. We present results for several underlying-event sensitive observables and compare to data from ATLAS and CMS as well as to standalone PYTHIA8 predictions. This includes a comparison with the recent ATLAS measurement of the beam thrust spectrum, which provides a potential avenue to fully disentangle the physical effects from the primary hard interaction, primary soft radiation, multiple parton interactions, and nonperturbative hadronization.Comment: 23 pages, 11 figures. v3: version accepted by EPJ

Preventing SDTs: Student Debt Troubles [brochure and streaming video]

In 2015, average student debt for graduates is higher than ever, even as the negative effects of outstanding student loan burdens – increased anxiety, reduced economic power, and delayed adult milestones – become increasingly well-documented (“Life Delayed”, 2013; Lusardi, 2010; Sparshott, 2015). A great number of programs, practices, and tips exist to help students cut costs and reduce the need for loans, but incoming college students are inadequately informed of these due to high student-to-high school counselor ratios and limited college-sponsored advising. This video presents to incoming college freshmen multiple expense-reducing ideas that are often missed in the current student advising climate, including strategic use of community college credit, national scholarship searches, work study programs, service programs, employers that provide tuition-assistance, resident assistantships, and joint bachelors/masters programs

Saturation and Σ2\Sigma_2-transfer for ERNA

Elementary Recursive Nonstandard Analysis, in short ERNA, is a constructive system of nonstandard analysis with a PRA consistency proof, proposed around 1995 by Patrick Suppes and Richard Sommer. It is built on a previous system by Rolando Chuaqui and Patrick Suppes, which was recently reconsidered by Michal R\"ossler and Emil Je\v{r}\'{a}bek. A $\Pi_{1} principle has already been added to ERNA and the consistency of the resulting theory proved in PRA. Here, we equip ERNA with$\Sigma_{2} and a saturation principle, while keeping the consistency proof inside PRA. We show that the extended theory allows for generalized transfer, a basic tool of nonstandard analysis, and interprets several strong theories, like \Sigma_{2}$and \Sigma_{2}$

Primordial black hole formation and abundance: contribution from the non-linear relation between the density and curvature perturbation

International audienceThe formation and abundance of primordial black holes (PBHs) arising from the curvature perturbation ζ is studied. The non-linear relation between ζ and the density contrast δ means that, even when ζ has an exactly Gaussian distribution, significant non-Gaussianities affecting PBH formation must be considered. Numerical simulations are used to investigate the critical value and the mass of PBHs which form, and peaks theory is used to calculate the mass fraction of the universe collapsing to form PBHs at the time of formation. A formalism to calculate the total present day PBH abundance and mass function is also derived. It is found that the abundance of PBHs is very sensitive to the non-linear effects, and that the power spectrum &calP;ζ must be a factor of &calO; (2) larger to produce the same number of PBHs as if using the linear relation between ζ and δ (where the exact value depends on the critical value for a region to collapse and form a PBH). This also means that the derived constraints on the small-scale power spectrum from constraints on the abundance of PBHs are weaker by the same factor