Conveners
Parallel Session D: Inflation
- Jisuke Kubo (Kanazawa University)
Parallel Session D: Reheating
- Ben Stefanek
Parallel Session D: Cosmology/Dark Energy
- Konstantinos Dimopoulos
Parallel Session D: Inflation
- Yusuke Yamada (Waseda university)
Parallel Session D: BSM
- Felix Bruemmer
Parallel Session D: Formal
- Jose A. R. Cembranos (Universidad Complutense de Madrid)
Antisymmetric tensor field (two-form field) is a ubiquitous component in string theory and generally couples to the scalar sector through its kinetic term. In this paper, we propose a cosmological scenario that the particle production of two-form field, which is triggered by the background motion of the coupled inflaton field, occurs at the intermediate stage of inflation and generates the...
In this talk, I will give a brief introduction to quintessential inflation, a theoretical framework that aims to explain both inflation and dark energy observations to alleviate the incredible fine-tuning of ΛCDM. Furthermore, I will show how adding both an R^2 Starobinsky term and a non-minimal coupling to the inflaton/quintessence field term in the action in the Palatini formalism can rescue...
It is becoming increasingly clear that large but rare fluctuations of the primordial curvature field, controlled by the tail of its probability distribution, could have dramatic effects on the current structure of the universe — e.g. via primordial black-holes. However, the use of standard perturbation theory to study the evolution of fluctuations during inflation fails in providing a reliable...
According to the standard model of cosmology, the Universe at its very beginning underwent a phase of rapid expansion, followed by a reheating period. During this epoch, the energy density, initially accumulated in the oscillations of the inflaton field, was injected into the visible sector, eventually setting the initial conditions for the hot big bang. In this talk, I will discuss the...
We discuss the energy distribution and equation of state of the universe between the end of inflation and the onset of radiation domination for observationally consistent single-field inflation scenarios, with a potential ’flattening’ at large field values and a monomial shape around the origin. As a proxy for (p)reheating, the inflaton is coupled to a light scalar field with a quadratic...
In inflationary cosmology, the Universe must transition from a state dominated by the nearly homogeneous inflaton condensate, into a state dominated by a hot bath of Standard Model particles, a process known as reheating. Detailed modelling of this transition often reveals the presence of exponentially growing instabilities, whose dynamics is typically referred to as preheating. A common...
One of the most basic open questions in cosmology is if dark energy is associated just with a cosmological constant or with something more involved. In this contribution, we emphasize that dark energy can be taken as constant under very general assumptions. Following this line of reasoning, we define the vacuum frame and discuss cosmological evolution from this new point of view.
We introduce the Cascading Dark Energy (CDE) scenario, in which one or some of the fields that contribute cooperatively to the recent cosmic acceleration, leave the band (cascade) and start acting on their own by oscillating around their minima. This process, in particular, could happen due to the different initial conditions of the field(s). Due to this dropout and energy injection, the...
The mechanism that produces the dark energy driving the expansion of the universe remains a mystery. One popular proposal is to have a scalar field play the role of dark energy. Such a field would have, at least, indirect coupling to matter and so result in a new fundamental force which could be used as a probe to detect these fields. However, no such 'fifth force' has been detected so far,...
The axionic inflaton with the Chern–Simons coupling may generate U(1) gauge fields and charged particles simultaneously. In order to incorporate the backreaction from the charged particles on the gauge fields, we develop a procedure to obtain an equilibrium solution for the gauge fields by treating the induced current as effective electric and magnetic conductivities. Introducing mean field...
The interaction between axion and gauge fields has been discussed in the contexts of inflationary models and primordial gravitational production. In this talk, we consider an inflationary model where SU(N) gauge fields couple to the inflaton through the Chern-Simons term. I will shortly review the dynamics of SU(2) gauge fields during inflation and then provide a general procedure to construct...
Heavy, unstable, and out-of-equilibrium particles with a matter equation of state appear in many well-motivated cosmological histories; examples include the inflaton condensate and moduli fields. Decays of the matter component result in highly relativistic non-thermal SM particles that must subsequently attain thermal equilibrium. We focus on cascades of $2 \to 3$ gauge interactions of the SM...
If gauge fields are coupled to an axion field during the inflationary epoch, they can lead to unique observational signatures. However, this system often shows strong backreaction effects, invalidating the standard perturbation theory approach. In this work, we present the first nonlinear lattice simulation of an axion-U(1) system during inflation. We use it to fully characterize the...
We study the nonlinear realization of supersymmetry in a dynamical/cosmological background in which derivative terms like kinetic terms are finite. Starting from linearly realized theories, we integrate out heavy modes without neglecting derivative terms to obtain algebraic constraints on superfields. Thanks to the supersymmetry breaking contribution by the kinetic energy, the validity of...
Particles coupled to inflaton have effective time-dependent masses due to the background inflaton field, which leads to the creation of the particles from the vacuum via non-perturbative processes known as preheating. We consider the decay process of such dressed particles by using the Furry perturbation theory, where the time-dependent mass is treated non-perturbatively whereas the...
We consider a massless minimally coupled quantum scalar field with an asymmetric (quartic plus cubic) self interaction,
V (φ) = λφ^4/4!+βφ^3/3! in the (3 + 1)-dimensional inflationary de Sitter background. This potential is bounded from below
regardless of the sign of β. The motivation of this study comes from the fact that such a potential may generate negative vacuum expectation value of...
The $R^2$-Higgs inflation is one of the best fit model to the data from Planck experiment. We show that the inflationary dynamics of $R^2$-Higgs inflation with two Higgs doublets favors nearly degenerate mass spectra for additional Higgs bosons. While satisfying all constraints from Planck 2018 data, such inflationary scenario leaves unique signatures for ongoing and future collider experiments.
There are interesting connections between searches for long-lived particles (LLPs) at the LHC and early universe cosmology. We study the non-thermal production of ultra-relativistic particles (i.e. dark radiation) in the early universe via the decay of weak-scale LLPs. The cosmologically interesting parameter space we find corresponds to LLP decay lengths which lie at the boundary between...
The charged wino decay plays an important role in the search for supersymmetric particles in accelerator experiments. We performed full one-loop calculation of the charged wino decay rate, which has not been done before, and improved the accuracy of theoretical predictions. By incorporating the effects of chiral perturbation theory and various quantum corrections, I will discuss that the decay...
In this talk I will show that the strong CP problem is solved in a large class of compactifications of string theory. The Peccei-Quinn mechanism solves the strong CP problem if the CP-breaking effects of the ultraviolet completion of gravity and of QCD are small compared to the CP-preserving axion potential generated by low-energy QCD instantons. We characterize both classes of effects. To...
My talk will be based on arXiv:2108.05372,2203.11959. I will explain how we obtain the deconfinement temperature of thermal QCD-like theories at intermediate coupling from ${\cal M}$-theory dual inclusive of ${\cal O}(R^4)$ corrections. In this process we found certain novel features such as "UV-IR" mixing, "Flavor Memory" effect and non-renormalization of the deconfinement temperature beyond...
The study of cosmological singularities in the context of string theory has been widely addressed on different time-dependent spacetime backgrounds and has never proved completely successful. Here we investigate the Null Boost Orbifold, which reproduces a Big-Bang type singularity but unfortunately suffers from unusual divergences when dealing with scattering amplitudes both in the closed and...
In my talk I will review the current status of higher and infinite derivative models of gravity heavily inspired and motivated by the String Field Theory. In particular I will address questions of unitarity of such models which are connected to works of Pius and Sen in SFT. Also potential renormalizability of these constructions as well as implication for the inflationary observables will be...
In this talk I will discuss higher order F^4-corrections on the type IIB scalar potential considering divisor topologies associated with Calabi Yau threefolds suitable for implementing the LARGE Volume Scenario for the moduli stabilization. I will focus on anlyzing the effects of such corrections on string inflationary model and, in particoular, on fiber and blow-up inflation. The obtained...
We present a model-independent, weighted semi-discrete optimal transport algorithm to reconstruct the Lagrangian positions of proto-halos from their evolved Eulerian positions. Tests with state-of-art cosmological simulations show that the positions of proto-halos are reconstructed accurately, without having to assume a background cosmology. The algorithm, which makes use of a mass estimate of...
