74 research outputs found
Unitarity and predictiveness in new Higgs inflation
In new Higgs inflation the Higgs kinetic terms are non-minimally coupled to
the Einstein tensor, allowing the Higgs field to play the role of the inflaton.
The new interaction is non-renormalizable, and the model only describes physics
below some cutoff scale. Even if the unknown UV physics does not affect the
tree level inflaton potential significantly, it may still enter at loop level
and modify the running of the Standard Model (SM) parameters. This is analogous
to what happens in the original model for Higgs inflation. A key difference,
though, is that in new Higgs inflation the inflationary predictions are
sensitive to this running. Thus the boundary conditions at the EW scale as well
as the unknown UV completion may leave a signature on the inflationary
parameters. However, this dependence can be evaded if the kinetic terms of the
SM fermions and gauge fields are non-minimally coupled to gravity as well. Our
approach to determine the model's UV dependence and the connection between low
and high scale physics can be used in any particle physics model of inflation.Comment: 21+6 pages, 1 figure; final version accepted by the journal,
improvements of section
Quantum corrections in Higgs inflation: the real scalar case
We present a critical discussion of quantum corrections, renormalisation, and
the computation of the beta functions and the effective potential in Higgs
inflation. In contrast with claims in the literature, we find no evidence for a
disagreement between the Jordan and Einstein frames, even at the quantum level.
For clarity of discussion we concentrate on the case of a real scalar Higgs. We
first review the classical calculation and then discuss the back reaction of
gravity. We compute the beta functions for the Higgs quartic coupling and
non-minimal coupling constant. Here, the mid-field regime is
non-renormalisable, but we are able to give an upper bound on the 1-loop
corrections to the effective potential. We show that, in computing the
effective potential, the Jordan and Einstein frames are compatible if all mass
scales are transformed between the two frames. As such, it is consistent to
take a constant cutoff in either the Jordan or Einstein frame, and both
prescriptions yield the same result for the effective potential. Our results
are extended to the case of a complex scalar Higgs.Comment: 28 pages, 1 figure. v2: minor changes, updated references, published
versio
The European Central Bank & crises measures. The role of the ECB during the euro-crisis and COVID-19 pandemic: investigating the independence and accountability.
This thesis investigates the role of the European Central Bank (ECB) during the eurocrisis and the COVID19 pandemic. It asks the question of whether the role of the ECB has affected the balance between independence and accountability. It does so by using a combination of economic and political theories to analyse the legal framework and actions of the ECB. This thesis furthermore places the actions in perspective by comparing with the US Federal Reserve (FED). This thesis starts in chapter 2 by examining the origins of central bank independence (CBI). Chapter 3 continues by defining the concept of accountability. This thesis uses the work of Amtenbrink (1999) to generate criteria for accountability. This chapter further examines the independence and accountability of the ECB and FED before the euro-crisis. Chapter 4 continues by examining the actions of the ECB through conventional policies. The role of the ECB during the euro crisis through its conventional policies was larger than expected. Chapter 5 of this research continues by evaluating the role of the ECB through its unconventional policies. Its role increased and changed from a cautious and conservative central bank to a more active bank. Chapter 6 of this thesis continues by examining the role of the ECB during the COVID19 crisis. Chapter 7 continues by discussing the judicial review. The level of judicial review both indicates the level of independence and the first step towards accountability. Chapter 8 continues by discussing the various methods of accountability. This chapter concludes that transparency has improved but that the main method of accountability has failed. Chapter 9 concludes that the new role of the ECB required higher levels of accountability. The accountability however did not develop to the level required, thus upsetting the balance between independence and accountability
Goldstone bosons and a dynamical Higgs field
Higgs inflation uses the gauge variant Higgs field as the inflaton. During
inflation the Higgs field is displaced from its minimum, which results in
associated Goldstone bosons that are apparently massive. Working in a minimally
coupled U(1) toy model, we use the closed-time-path formalism to show that
these Goldstone bosons do contribute to the one-loop effective action.
Therefore the computation in unitary gauge gives incorrect results. Our
expression for the effective action is gauge invariant upon using the
background equations of motion.Comment: 27 pages, 2 figures, published version with minor correction
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Corporate image: a service recovery perspective
This article explores direct and indirect antecedents that contribute to corporate image formation in a service recovery context. Two studies were carried out in Egypt. Study 1 comprises 29 semistructured interviews with complainants of mobile phone network service providers in Egypt. Study 2 encompasses a mail survey of another 437 complainants. Findings reveal the importance of perceived justice, namely, interactional justice, in corporate image formation, as well as the mediating role of satisfaction with service recovery in the perceived justice-corporate image relationship. Results also reveal two empirical relationships: problem solving as a determinant of distributive justice and follow-up as a driver of procedural justice. Accordingly, this study contributes to the service field by providing the first empirical evaluation of new direct and indirect antecedents of corporate image formation in a service recovery context. Managerial recommendations are provided that encourage service practitioners to emphasize perceived justice and satisfaction with a service recovery process to enhance the company’s image. Additionally, companies should invest in implementing problem solving and follow-up as service recovery strategies since both significantly enhance perceived justice
Wind-induced resuspension in a shallow lake from Medium Resolution Imaging Spectrometer (MERIS) full-resolution reflectances
A lack of empirical evidence impedes assessment of the spatial and temporal extent of critical conditions for recurring high turbidity in large wind-exposed shallow lakes. Here spatiotemporal variation in total suspended matter (TSM) concentration was captured by processing 30 Envisat Medium Resolution Imaging Spectrometer (MERIS) images of a shallow lake (Markermeer) with a spectral matching algorithm. The TSM maps showed elevated downwind concentrations for moderate winds (from 4 to 9 m
Exploring, exploiting and evolving diversity of aquatic ecosystem models: A community perspective
Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary
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