A Strong Electroweak Phase Transition from the Inflaton Field

We study a singlet scalar extension of the Standard Model. The singlet scalar is coupled non-minimally to gravity and assumed to drive inflation, and also couple sufficiently strongly with the SM Higgs field in order to provide for a strong first order electroweak phase transition. Requiring the model to describe inflation successfully, be compatible with the LHC data, and yield a strong first order electroweak phase transition, we identify the regions of the parameter space where the model is viable. We also include a singlet fermion with scalar coupling to the singlet scalar to probe the sensitivity of the constraints on additional degrees of freedom and their couplings in the singlet sector. We also comment on the general feasibility of these fields to act as dark matter.Comment: 16 pages, 3 figures; minor changes to match the published versio

Developing web application and hybrid application; How developing for different platforms differentiated and how users experienced these

The mobile application development process is evolving rapidly, and new frameworks are created every month. When choosing how to develop mobile application, there are three main development platforms: web application, native application, and hybrid application. These all have their positives and negatives, and they all have their own strengths when chosen for right kind of project. Previous research has been conducted but they have mixed results when comparing. Thus, this research was made to investigate more closely how the development process for web application and hybrid application differentiated and how the end product applications differentiated, when analysing the experiences of the users. Two applications were developed during this research: React.js application for web development and React Native for hybrid development. To analyse users experience, web and hybrid versions of the same application was given to the participants. First the participants were asked to test the main functionalities of the application, and after testing answering the survey. The survey tried to ask how positive or negative some of the features of the applications were. In conclusion, the study shows that the hybrid application version was superior. In the survey hybrid application had slightly more positive answers and was clearly faster version of the two. The development process for the web application was easier and had better options for choosing the best suitable tools and libraries.Mobiilisovellusten ohjelmointi prosessit kehittyvät nopeasti, ja uusia ohjelmointityökaluja julkaistaan joka kuukausi. Mobiilisovelluksen kehittämistä valittaessa on kolme pääkehitysalustaa: verkko-, natiivi- ja hybridisovellus. Näillä kaikilla on positiiviset ja negatiiviset puolensa, sekä omat vahvuutensa, kun ne valitaan oikeanlaiseen projektiin. Aikaisempia tutkimuksia on tehty, mutta näiden tulokset ovat ristiriitaisia. Näin ollen tämä tutkimus tehtiin tarkentamaan, miten verkko- ja hybridisovelluksen kehitysprosessi eroavat ja miten lopputuotteet erottuivat käyttäjien kokemuksia analysoitaessa. Tämän tutkimuksen aikana kehitettiin kaksi sovellusta: React.js - sovellus verkkokehitykseen ja React Native hybridikehitykseen. Käyttäjäkokemuksen analysoimiseksi osallistujille annettiin samasta sovelluksesta verkko- ja hybridiversiot. Ensin osallistujia pyydettiin testaamaan sovelluksen päätoimintoja ja testauksen jälkeen vastaamaan kyselyyn. Kyselyn tavoite oli mitata, kuinka positiivisia tai negatiivisia jotkin sovellusten ominaisuudet olivat. Tutkimus osoitti, että hybridisovellusversio oli parempi kuin verkkosovellusversio. Kyselyssä hybridisovellus sai hieman enemmän myönteisiä vastauksia ja oli selvästi nopeampi versio näistä kahdesta. Verkkosovelluksen kehitysprosessi oli helpompaa ja siinä oli paremmat mahdollisuudet valita sopivimmat työkalut ja kirjastot

Observational Properties of Feebly Coupled Dark Matter

We show that decoupled hidden sectors can have observational consequences. As a representative model example, we study dark matter production in the Higgs portal model with one real singlet scalar $s$ coupled to the Standard Model Higgs via $\lambda_{\rm hs}\Phi^\dagger\Phi s^2$ and demonstrate how the combination of non-observation of cosmological isocurvature perturbations and astrophysical limits on dark matter self-interactions imply stringent bounds on the magnitude of the scalar self-coupling $\lambda_{\rm s}s^4$. For example, for dark matter mass $m_{\rm s}=10$ MeV and Hubble scale during cosmic inflation $H_*=10^{12}$ GeV, we find $10^{-4}\lesssim \lambda_{\rm s}\lesssim 0.2$.Comment: 4 pages, 1 figure. Prepared for the proceedings of the ICHEP2016 conference, 3-10 August 2016, Chicago, United State

Scalar correlation functions in de Sitter space from the stochastic spectral expansion

We consider light scalar fields during inflation and show how the stochastic spectral expansion method can be used to calculate two-point correlation functions of an arbitrary local function of the field in de Sitter space. In particular, we use this approach for a massive scalar field with quartic self-interactions to calculate the fluctuation spectrum of the density contrast and compare it to other approximations. We find that neither Gaussian nor linear approximations accurately reproduce the power spectrum, and in fact always overestimate it. For example, for a scalar field with only a quartic term in the potential, $V=\lambda\phi^4/4$, we find a blue spectrum with spectral index $n-1=0.579\sqrt{\lambda}$.Comment: 21 pages, 4 figures, 2 tables. v2: minor revision, version published in JCA