arXiv subjects

Jonas Müller

Publications and source records attributed to Jonas Müller.

35 records · Page 2Linked to original sources

arXiv2023

Control of light emission of quantum emitters coupled to silicon nanoantenna using cylindrical vector beams

Light emission of europium (Eu3+) ions placed in the vicinity of optically resonant nanoantennas is usually controlled by tailoring the local density of photon states (LDOS). We show that the polarization and shape of the excitation beam can also be used to manipulate light emission, as azimuthally or radially polarized cylindrical vector beam offers to spatially shape the electric and magnetic fields, in addition to the effect of silicon nanorings (Si-NRs) used as nanoantennas. The photoluminescence mappings of the Eu3+ transitions and the Si phonon mappings are strongly dependent of both the excitation beam and the Si-NR dimensions. The experimental results of Raman scattering and photoluminescence are confirmed by numerical simulations of the near-field intensity in the Si nanoantenna and in the Eu3+-doped film, respectively. The branching ratios obtained from the experimental PL maps also reveal a redistribution of the electric and magnetic emission channels. Our results show that it is possible to spatially control both electric and magnetic dipolar emission of Eu3+ ions by switching the laser beam polarization, hence the near-field at the excitation wavelength, and the electric and magnetic LDOS at the emission wavelength. This paves the way for optimized geometries taking advantage of both excitation and emission processes.

physics.optics↗

arXiv2023

`CP in the Dark' and a Strong First-Order Electroweak Phase Transition

We investigate the potential of the model `CP in the Dark' for providing a strong first-order electroweak phase transition (SFOEWPT) by taking into account all relevant theoretical and experimental constraints. For the derivation of the strength of the phase transition we use the one-loop corrected, daisy-resummed effective potential at finite temperature, implemented in the C++ code BSMPT, to determine the global minimum at the critical temperature. The model `CP in the Dark' provides a dark matter (DM) candidate as well as explicit CP violation in the dark sector. We find a broad range of viable parameter points providing an SFOEWPT. They are within the reach of XENON1T and future invisible Higgs decay searches for DM. `CP in the Dark' also offers SFOEWPT points that feature spontaneous CP violation at finite temperature. Having not only an SFOEWPT that provides the necessary departure from thermal equilibrium, but also a source of additional non-standard CP violation, opens a promising gate towards enabling the generation of the baryon asymmetry of the universe (BAU) through electroweak baryogenesis.

hep-ph↗

arXiv2022

Probing the optical near-field interaction of Mie nanoresonators with atomically thin semiconductors

Optical Mie resonators based on silicon nanostructures allow tuning of light-matter-interaction with advanced design concepts based on CMOS compatible nanofabrication. Optically active materials such as transition-metal dichalcogenide (TMD) monolayers can be placed in the near-field region of such Mie resonators. Here, we experimentally demonstrate and verify by numerical simulations coupling between a MoSe2 monolayer and the near-field of dielectric nanoresonators. Through a comparison of dark-field (DF) scattering spectroscopy and photoluminescence excitation experiments (PLE), we show that the MoSe2 absorption can be enhanced via the near-field of a nanoresonator. We demonstrate spectral tuning of the absorption via the geometry of individual Mie resonators. We show that we indeed access the optical near-field of the nanoresonators, by measuring a spectral shift between the typical near-field resonances in PLE compared to the far-field resonances in DF scattering. Our results prove that using MoSe2 as an active probe allows accessing the optical near-field above photonic nanostructures, without the requirement of highly complex near-field microscopy equipment.

physics.optics↗

arXiv2022

Semi-Parametric Neural Image Synthesis

Novel architectures have recently improved generative image synthesis leading to excellent visual quality in various tasks. Much of this success is due to the scalability of these architectures and hence caused by a dramatic increase in model complexity and in the computational resources invested in training these models. Our work questions the underlying paradigm of compressing large training data into ever growing parametric representations. We rather present an orthogonal, semi-parametric approach. We complement comparably small diffusion or autoregressive models with a separate image database and a retrieval strategy. During training we retrieve a set of nearest neighbors from this external database for each training instance and condition the generative model on these informative samples. While the retrieval approach is providing the (local) content, the model is focusing on learning the composition of scenes based on this content. As demonstrated by our experiments, simply swapping the database for one with different contents transfers a trained model post-hoc to a novel domain. The evaluation shows competitive performance on tasks which the generative model has not been trained on, such as class-conditional synthesis, zero-shot stylization or text-to-image synthesis without requiring paired text-image data. With negligible memory and computational overhead for the external database and retrieval we can significantly reduce the parameter count of the generative model and still outperform the state-of-the-art.

cs.CV↗

arXiv2022

Electroweak Phase Transition in a Dark Sector with CP Violation

In this paper, we investigate the possibility of a strong first-order electroweak phase transition (SFOEWPT) in the model `CP in the Dark'. The Higgs sector of the model consists of two scalar doublets and one scalar singlet with a specific discrete symmetry. After spontaneous symmetry breaking the model has a Standard-Model-like phenomenology and a hidden scalar sector with a viable Dark Matter candidate supplemented by explicit CP violation that solely occurs in the hidden sector. The model `CP in the Dark' has been implemented in the C++ code BSMPT v2.3 which performs a global minimisation of the finite-temperature one-loop corrected effective potential and searches for SFOEWPTs. An SFOEWPT is found to be allowed in a broad range of the parameter space. Furthermore, there are parameter scenarios where spontaneous CP violation is generated at finite temperature. The in addition spontaneously broken $\mathbb{Z}_2$ symmetry then leads to mixing between the dark and the visible sector so that CP violation in the dark is promoted at finite temperature to the visible sector and thereby provides additional sources of CP violation that are not restricted by the electric dipole moment measurements at zero temperature. Thus, `CP in the Dark' provides a promising candidate for the generation of the baryon asymmetry of the universe through electroweak baryogenesis.

hep-ph↗

arXiv2022

Electroweak Corrections to Dark Matter Direct Detection in the Dark Singlet Phase of the N2HDM

Direct detection experiments are the only way to obtain indisputable evidence of the existence of dark matter (DM) in the form of a particle. These experiments have been used to probe many extensions of the Standard Model (SM) that provide DM candidates. Experimental results like the latest ones from XENON1T lead to severe constraints in the parameter space of many of the proposed models. In a simple extension of the SM, the addition of a complex singlet to the SM content, one-loop corrections need to be taken into account because the tree-level cross section is proportional to the DM velocity, and therefore negligible. In this work we study the case of a DM particle with origin in a singlet but in a larger framework of an extension by an extra doublet together with the extra singlet providing the DM candidate. We show that in the region of interest of the present and future direct detection experiments, electroweak corrections are quite stable with a $K$-factor very close to one.

hep-ph↗

arXiv2021

Electroweak Baryogenesis in the CP-Violating Two-Higgs Doublet Model

Recently we presented the upgrade of our code BSMPT for the calculation of the electroweak phase transition (EWPT) to BSMPT v2 which now includes the computation of the baryon asymmetry of the universe (BAU) in the CP-violating 2-Higgs-Doublet Model (C2HDM). In this paper we use {\tt BSMPT v2} to investigate the size of the BAU that is obtained in the C2HDM with the two implemented approaches FH and VIA to derive the transport equations, by taking into account all relevant theoretical and experimental constraints. We identify similarities and differences in the results computed with the two methods. In particular, we analyse the dependence of the obtained BAU on the parameters relevant for successful baryogenesis. Our investigations allow us to pinpoint future directions for improvements both in the computation of the BAU and in possible avenues taken for model building.

hep-ph↗

arXiv2021

Electroweak Phase Transitions with BSM Fermions

We study the impact of additional beyond-the-Standard Model (BSM) fermions, charged under the Standard Model (SM) $SU(2)_L \otimes U(1)_Y$ gauge group, on the electroweak phase transition (EWPT) in a 2-Higgs-Doublet-Model (2HDM) of type II. We find that the strength of the EWPT can be enhanced by about 40% compared to the default 2HDM. Therefore, additional light fermions are a useful tool to weaken the tension between increasing mass constraints on BSM scalars and the requirement of additional light scalar degrees of freedom to accommodate a strong first order EWPT. The findings are of particular interest for a variety of (non-minimal) split supersymmetry scenarios which necessarily introduce additional light fermion degrees of freedom.

hep-ph↗

arXiv2021

The water-ice line as a birthplace of planets: Implications of a species-dependent dust fragmentation threshold

The thermodynamic structure of protoplanetary discs is determined by dust opacities, which depend on the size of the dust grains and their chemical composition. In the inner regions, the grain sizes are regulated by the level of turbulence (e.g. $α$ viscosity) and by the dust fragmentation velocity that represents the maximal velocity that grains can have at a collision before they fragment. Here, we perform self-consistently calculated 2D hydrodynamical simulations that consider a full grain size distribution of dust grains with a transition in the dust fragmentation velocity at the water-ice line. This approach accounts for the results of previous particle collision laboratory experiments, in which silicate particles typically have a lower dust fragmentation velocity than water-ice particles. Furthermore, we probe the effects of variations in the water abundance, the dust-to-gas ratio, and the turbulence parameter on the disc structure. For the discs with a transition in the dust fragmentation velocity at the water-ice line, we find a narrow but striking zone of planetary outward migration, including for low viscosities. In addition, we find a bump in the radial pressure gradient profile that tends to be located slightly inside the ice line. Both of these features are present for all tested disc parameters. Thus, we conclude that the ice line can function both as a migration trap, which can extend the growth times of planets before they migrate to the inner edge of the protoplanetary disc, and as a pressure trap, where planetesimal formation can be initiated or enhanced.

astro-ph.EP↗

arXiv2020

Spatial structuring of light for undergraduate laboratory

In recent times, spatial light modulators have become a common tool in optics laboratories as well as industrial environment to shape the spatial structure of a beam. Although these devices are often easy to use, they usually come at a high cost such that they are far from being implemented in a lot of undergraduate laboratories. However, over the last years, the progress in developing more cost-effective projectors has led to affordable spatial light modulators in the form of so-called Digital Micromirror Devices (DMD). This reduction in price, as well as their simple usage, make such devices increasingly suitable for undergraduate laboratories to demonstrate optical effects and the shaping of light fields. Here, we show one of the most cost-effective ways to make a DMD available, namely turning a projector evaluation module into a computer-controlled spatial light modulator. We explain the underlying functioning and how this low-cost spatial light modulator can be used in undergraduate laboratories. We further characterize the efficiency of the device for the most commonly used laser wavelengths and demonstrate various exemplary optics experiments suitable for undergraduate laboratories ranging from single and multi-slit diffraction, to optical Fourier transformations. Lastly, we show that using amplitude holography, the device can be used to generate transverse spatial modes, e.g. Laguerre-Gaussian beam, which are one of the most commonly used spatially structured beams.

physics.ed-ph↗

arXiv2020

Electroweak Corrections in a Pseudo-Nambu Goldstone Dark Matter Model Revisited

Having so far only indirect evidence for the existence of Dark Matter a plethora of experiments aims at direct detection of Dark Matter through the scattering of Dark Matter particles off atomic nuclei. For the correct interpretation and identification of the underlying nature of the Dark Matter constituents higher-order corrections to the cross section of Dark Matter-nucleon scattering are important, in particular in models where the tree-level cross section is negligibly small. In this work we revisit the electroweak corrections to the dark matter-nucleon scattering cross section in a model with a pseudo Nambu-Goldstone boson as the Dark Matter candidate. Two calculations that already exist in the literature, apply different approaches resulting in different final results for the cross section in some regions of the parameter space leading us to redo the calculation and analyse the two approaches to clarify the situation. We furthermore update the experimental constraints and examine the regions of the parameter space where the cross section is above the neutrino floor but which can only be probed in the far future.

hep-ph↗

arXiv2020

NLO corrections to Vector Dark Matter Direct Detection -- An update

In this work we present an update to a previous calculation of the Next-to-Leading Order (NLO) corrections to the Vector Dark Matter (VDM) direct detection cross section. The model under investigation is a minimal extension of the Standard Model (SM) with one extra vector boson and one extra complex scalar field, where the vector is the DM candidate. We have computed the spin-independent cross section for the scattering of the VDM particle with a nucleon. We now provide an update to the NLO cross section for the direct detection of the DM particle. We further discuss the phenomenological implications of the NLO corrections for the sensitivity of the direct detection DM experiments.

hep-ph↗

arXiv2019

Estimating Cardinalities with Deep Sketches

We introduce Deep Sketches, which are compact models of databases that allow us to estimate the result sizes of SQL queries. Deep Sketches are powered by a new deep learning approach to cardinality estimation that can capture correlations between columns, even across tables. Our demonstration allows users to define such sketches on the TPC-H and IMDb datasets, monitor the training process, and run ad-hoc queries against trained sketches. We also estimate query cardinalities with HyPer and PostgreSQL to visualize the gains over traditional cardinality estimators.

cs.DB↗

arXiv2019

An extended model of wine fermentation including aromas and acids

The art of viticulture and the quest for making wines has a long tradition and it just started recently that mathematicians entered this field with their main contribution of modelling alcoholic fermentation. These models consist of systems of ordinary differential equations that describe the kinetics of the bio-chemical reactions occurring in the fermentation process. The aim of this paper is to present a new model of wine fermentation that accurately describes the yeast dying component, the presence of glucose transporters, and the formation of aromas and acids. Therefore the new model could become a valuable tool to predict the taste of the wine and provide the starting point for an emerging control technology that aims at improving the quality of the wine by steering a well-behaved fermentation process that is also energetically more efficient. Results of numerical simulations are presented that successfully confirm the validity of the proposed model by comparison with real data.

q-bio.MN↗

arXiv2014

Novel model for wine fermentation including the yeast dying phase

This paper presents a novel model for wine fermentation including a death phase for yeast and the influence of oxygen on the process. A model for the inclusion of the yeast dying phase is derived and compared to a model taken from the literature. The modeling ability of the several models is analyzed by comparing their simulation results.

q-bio.QM↗

arXiv2014

Grid Integration Costs of Fluctuating Renewable Energy Sources

The grid integration of intermittent Renewable Energy Sources (RES) causes costs for grid operators due to forecast uncertainty and the resulting production schedule mismatches. These so-called profile service costs are marginal cost components and can be understood as an insurance fee against RES production schedule uncertainty that the system operator incurs due to the obligation to always provide sufficient control reserve capacity for power imbalance mitigation. This paper studies the situation for the German power system and the existing German RES support schemes. The profile service costs incurred by German Transmission System Operators (TSOs) are quantified and means for cost reduction are discussed. In general, profile service costs are dependent on the RES prediction error and the specific workings of the power markets via which the prediction error is balanced. This paper shows both how the prediction error can be reduced in daily operation as well as how profile service costs can be reduced via optimization against power markets and/or active curtailment of RES generation.

q-fin.GN↗

arXiv2011

Measurement of the double polarisation observable E in single pseudoscalar meson production

Polarisation observables are measured with the Crystal Barrel/TAPS experiment at ELSA for photoproduction reactions with various final states, using a circularly or linearly polarised photon beam and a longitudinally or transversely polarised frozen spin butanol target. The Crystal Barrel/TAPS setup provides a nearly 4$π$ angular coverage, a good energy resolution and a high detection efficiency for photons, and is therefore ideally suited to study final states comprising neutral mesons. Results for the measurement of the double polarisation observable E for pion and eta photoproduction off the proton are presented.

nucl-ex↗