Probing dark matter clumps, strings and domain walls with gravitational wave detectors

Gravitational wave astronomy has recently emerged as a new way to study our Universe. In this work, we survey the potential of gravitational wave interferometers to detect macroscopic astrophysical objects comprising the dark matter. Starting from the well-known case of clumps we expand to cosmic strings and domain walls. We also consider the sensitivity to measure the dark matter power spectrum on small scales. Our analysis is based on the fact that these objects, when traversing the vicinity of the detector, will exert a gravitational pull on each node of the interferometer, in turn leading to a differential acceleration and corresponding Doppler signal, that can be measured. As a prototypical example of a gravitational wave interferometer, we consider signals induced at LISA. We further extrapolate our results to gravitational wave experiments sensitive in other frequency bands, including ground-based interferometers, such as LIGO, and pulsar timing arrays, e.g. ones based on the Square Kilometer Array. Assuming moderate sensitivity improvements beyond the current designs, clumps, strings and domain walls may be within reach of these experiments

How Many Higgs Bosons Does it Take: Consistency of Scalar Field Theories at High Energies

Computations of multiparticle scattering amplitudes in scalar field theories at high multiplicities hint at a rapid growth with the number of final state particles, rendering the theory in conflict with unitarity at high energies. This questions the validity of the perturbative approach or even the interpretation of the underlying quantum field theory. We study the quantum mechanical equivalent of high multiplicity amplitudes in $\lambda \phi^4$-theory, namely transition amplitudes from the vacuum to highly excited states in the anharmonic oscillator with a quartic potential. Using recursive relations, we compute these amplitudes to high order in perturbation theory and provide evidence that they can be written in exponential form. By resummation techniques, we then construct its exponent beyond leading order and investigate the behaviour of the amplitudes in the region where tree-level perturbation theory violates unitarity constraints. We find that for both the single- and the double-well potential the resummed amplitudes are in agreement with unitarity bounds. We then extend our results to anharmonic oscillators with general monomial potentials and point out possible problems of perturbative expansions even in potentials with a single minimum. Finally, we comment on the relevance of our results for the field theoretical problem

Quantum Imprint of the Anharmonic Oscillator

We study the anharmonic double well in quantum mechanics using exact Wentzel-Kramers-Brillouin (WKB) methods in a 't Hooft-like double scaling limit where classical behavior is expected to dominate. We compute the tunneling action in this double scaling limit, and compare it to the transition amplitude from the vacuum to a highly excited state. Our results, exact in the semiclassical limit, show that the two expressions coincide, apart from an irreducible and surprising instanton contribution. Thus, the semiclassical limit of the anharmonic oscillator betrays its quantum origin as a rule, which we dub the "quantum imprint rule," showing that the quantum theory is intrinsically gapped from classical behavior. Besides an example of the failure of reductionism and an example of a resurgent connection between perturbative and nonperturbative physics, this work provides a possible classification of theories according to their quantum imprints.Comment: 23 page

Perinatal mental health care from the user and provider perspective: protocol for a qualitative study in Switzerland

Background: Mental disorders in the perinatal period (PMD) can severely harm women and their children if not detected early and treated appropriately. Even though mental health care is covered by health insurance and is used widely by women in the perinatal period in Switzerland, it is not known if the care provided is meeting the needs of the patients and is efficient in the view of health care professionals. The aim of this study is to identify strengths, gaps and requirements for adequate mental health care in the perinatal period from the perspectives of patients and care providers for a wide range of relevant mental disorders. Methods: In the qualitative study we conduct (1) semi-structured single interviews with former PMD patients to obtain narratives about their experiences and needs for health care for their condition. Women are included who have been treated for PMD but are mentally stable at the time of the interview (n = 24). We will stratify the sample by 4 clusters of relevant ICD-10 F-diagnoses, covering the most frequent and the most severe mental disorders. We will further stratify the sample based on whether the women already had experience with psychiatric or psychological health care or not before their last episode of PMD. We will also conduct (2) three interprofessional focus groups with health and social care professionals involved in perinatal care, and a health insurance representative. The focus groups will consist of 5–8 professionals. Data collection and thematic analysis will consider Levesque’s et al. (2013) conceptual model on access to health care. Discussion: The study will provide fundamental data on the experiences and perspectives about perinatal mental health care from user and provider perspectives. The study will generate the evidence base needed to develop models of integrated, coordinated, patient- and family-centred care that is accessed by women with various types of PMD. Trial registration: The study was registered on ClinicalTrials.gov in November 2019 under the identifier NCT04185896