Searching for dark matter with plasma haloscopes

We summarize the recent progress of the Axion Longitudinal Plasma Haloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space

Searching For Dark Matter with Plasma Haloscopes

We summarise the recent progress of the Axion Longitudinal Plasma HAloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the Strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space.Comment: Endorsers: Jens Dilling, Michael Febbraro, Stefan Knirck, and Claire Marvinney. 26 pages, 17 figures, version accepted in Physical Review

Getting the first job: Size and quality of ethnic enclaves and refugee labor market entry

We analyze the relationship between residence in an ethnic enclave and immigrants' labor market integration with respect to finding a first job in the receiving country. The analysis distinguishes between the size and the quality of the ethnic enclaves, where quality is measured in terms of employment rate among ethnic peers in the same neighborhood. We use longitudinal geo‐coded registry data for two distinct groups of immigrants arriving in the Stockholm metropolitan area to investigate their initial labor market contact. The first group of immigrants moved from the Balkans in the early 1990s following the Yugoslavian war, and the second group arrived from the Middle East following the second Iraq War in 2006. We estimate the probability of finding a first job using probit regressions and complement the analysis with additional duration models. To draw causal inference, we use instrumentation that combines initial neighborhood variables with citywide variation over time. We provide empirical evidence that the employment rate of the respective immigrant group in the vicinity facilitates labor market integration of new immigrants. The influences of the overall employment rate and the share of conationals in the neighborhood tend to be positive, but less robustly so. Our results are consistent with the notion that the qualitative nature of an enclave is at least as important as the sheer number of ethnic peers in helping new immigrants find jobs.Johan Klaesson thanks for financial support from Forte (grant number: 2019‐01320)

Long-term persistence of oligoclonal serum IgM repertoires in patients treated with allogeneic bone marrow transplantation (BMT)

Immunoglobulin gene rearrangements in patients treated with BMT have restricted repertoire diversity. Clonal variability remains low for 3 months and reconstitution of the humoral immune system appears to follow a wave-like pattern. In the present study we analysed serum IgM and IgG repertoires in 44 patients from 1 week to 3 years after transplantation. We applied a quantitative immunoblot technique in combination with a newly developed method for estimation of repertoire diversity in complex mixtures of antibodies. Our results demonstrate that 60% of BMT patients have severely reduced diversity in the IgM repertoire during and after the first year post-BMT, compared with healthy controls. In contrast, the majority of patients have a polyclonal IgG repertoire, similar to that of healthy controls. Serum IgM repertoires remain oligoclonal even though the serum concentration of total IgM is within normal range around 6 months post-BMT. During the first years after transplantation IgM as well as IgG repertoires are less diverse in patients receiving a BM graft from a sibling donor compared with those receiving a graft from an HLA-matched unrelated donor. Patients in the latter group show a higher incidence of infections and minor antigen mismatches which may promote the development of a diverse immunoglobulin repertoire post-BMT