Recommended conventions for reporting results from direct dark matter searches

The field of dark matter detection is a highly visible and highly competitive one. In this paper, we propose recommendations for presenting dark matter direct detection results particularly suited for weak-scale dark matter searches, although we believe the spirit of the recommendations can apply more broadly to searches for other dark matter candidates, such as very light dark matter or axions. To translate experimental data into a final published result, direct detection collaborations must make a series of choices in their analysis, ranging from how to model astrophysical parameters to how to make statistical inferences based on observed data. While many collaborations follow a standard set of recommendations in some areas, for example the expected flux of dark matter particles (to a large degree based on a paper from Lewin and Smith in 1995), in other areas, particularly in statistical inference, they have taken different approaches, often from result to result by the same collaboration. We set out a number of recommendations on how to apply the now commonly used Profile Likelihood Ratio method to direct detection data. In addition, updated recommendations for the Standard Halo Model astrophysical parameters and relevant neutrino fluxes are provided. The authors of this note include members of the DAMIC, DarkSide, DARWIN, DEAP, LZ, NEWS-G, PandaX, PICO, SBC, SENSEI, SuperCDMS, and XENON collaborations, and these collaborations provided input to the recommendations laid out here. Wide-spread adoption of these recommendations will make it easier to compare and combine future dark matter results

Removing krypton from xenon by cryogenic distillation to the ppq level

The XENON1T experiment aims for the direct detection of dark matter in a cryostat filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the $\beta$-emitter $^{85}$Kr which is an intrinsic contamination of the xenon. For the XENON1T experiment a concentration of natural krypton in xenon $\rm{^{nat}}$Kr/Xe < 200 ppq (parts per quadrillion, 1 ppq = 10$^{-15}$ mol/mol) is required. In this work, the design of a novel cryogenic distillation column using the common McCabe-Thiele approach is described. The system demonstrated a krypton reduction factor of 6.4$\cdot$10$^5$ with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of $\rm{^{nat}}$Kr/Xe < 26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN

Hepatocellular Carcinoma in HIV-infected Patients: Check Ealy, Treat Hard

Purpose. Hepatocellular carcinoma (HCC) is an increasingcause of mortality in HIV-infected patients inthe highly active antiretroviral therapy (HAART) era.The aims of this study were to describe HCC tumorcharacteristics and different therapeutic approaches, toevaluate patient survival time from HCC diagnosis, andto identify clinical prognostic predictors in patients withand without HIV infection.Patients and Methods. A multicenter observationalretrospective comparison of 104 HIV-infected patientsand 484 uninfected patients was performed in four Italiancenters. HCC was staged according to the BarcelonaClinic Liver Cancer (BCLC) criteria.Results. Tumor characteristics of patients with andwithout HIV were significantly different for age, EasternCooperative Oncology Group performance status(PS) score <1, and etiology of chronic liver disease. Despitethe similar potentially curative option rate and better BCLC stage at diagnosis, the median survivaltime was significantly shorter in HIV patients. HIVpatients were less frequently retreated at relapse.Independent predictors of survival were: BCLC stage,potentially effective HCC therapy, tumor dimension <3cm, HCC diagnosis under a screening program, HCC recurrence,and portal vein thrombosis. Restricting the analysisto HIV patients only, all positive prognostic factorswere confirmed together with HAART exposure.Conclusion. This study confirms a significantlyshorter survival time in HIV HCC patients. The lessaggressive retreatment at recurrence approach does notbalance the benefit of younger age and better BCLCstage and PS score of HIV patients. Thus, consideringthe prognosis of HIV HCC patients, effective screeningtechniques, programs, and specific managementguidelines are urgently needed

Biodiversity of Indigenous Saccharomyces Populations from Old Wineries of South-Eastern Sicily (Italy): Preservation and Economic Potential

In recent years, the preservation of biodiversity has become an important issue. Despite much public discussion, however, current practices in the food industry seldom take account of its potential economic importance: on the contrary, the introduction of industrialized agriculture practices over large areas has often resulted in a dramatic reduction in biodiversity

Effective Field Theory and Inelastic Dark Matter Results from XENON1T

In this work, we expand on the XENON1T nuclear recoil searches to study theindividual signals of dark matter interactions from operators up todimension-eight in a Chiral Effective Field Theory (ChEFT) and a model ofinelastic dark matter (iDM). We analyze data from two science runs of theXENON1T detector totaling 1\,tonne$\times$year exposure. For these analyses, weextended the region of interest from [4.9, 40.9]$\,$keV$_{\text{NR}}$ to [4.9,54.4]$\,$keV$_{\text{NR}}$ to enhance our sensitivity for signals that peak atnonzero energies. We show that the data is consistent with the background-onlyhypothesis, with a small background over-fluctuation observed peaking between20 and 50$\,$keV$_{\text{NR}}$, resulting in a maximum local discoverysignificance of 1.7\,$\sigma$ for the Vector$\otimes$Vector$_{\text{strange}}$($VV_s$) ChEFT channel for a dark matter particle of 70$\,$GeV/c$^2$, and$1.8\,\sigma$ for an iDM particle of 50$\,$GeV/c$^2$ with a mass splitting of100$\,$keV/c$^2$. For each model, we report 90\,\% confidence level (CL) upperlimits. We also report upper limits on three benchmark models of dark matterinteraction using ChEFT where we investigate the effect of isospin-breakinginteractions. We observe rate-driven cancellations in regions of theisospin-breaking couplings, leading to up to 6 orders of magnitude weaker upperlimits with respect to the isospin-conserving case.<br

Emission of single and few electrons in XENON1T and limits on light dark matter

Delayed single- and few-electron emissions plague dual-phase time projection chambers, limiting their potential to search for light-mass dark matter. This paper examines the origins of these events in the XENON1T experiment. Characterization of the intensity of delayed electron backgrounds shows that the resulting emissions are correlated, in time and position, with high-energy events and can effectively be vetoed. In this work we extend previous S2-only analyses down to a single electron. From this analysis, after removing the correlated backgrounds, we observe rates <30 events/(electron×kg×day) in the region of interest spanning 1 to 5 electrons. We derive 90% confidence upper limits for dark matter-electron scattering, first direct limits on the electric dipole, magnetic dipole, and anapole interactions, and bosonic dark matter models, where we exclude new parameter space for dark photons and solar dark photons

Search for New Physics in Electronic Recoil Data from XENONnT

We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3)  events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter

An approximate likelihood for nuclear recoil searches with XENON1T data

The XENON collaboration has published stringent limits on specific dark matter – nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 t-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method we present. The approximate likelihood is constructed in bins of reconstructed energy, profiled along the signal expectation in each bin. This approach can be used to compute an approximate likelihood and therefore most statistical results for any nuclear recoil spectrum. Computing approximate results with this method is approximately three orders of magnitude faster than the likelihood used in the original publications of XENON1T, where limits were set for specific families of recoil spectra. Using this same method, we include toy Monte Carlo simulation-derived binwise likelihoods for the upcoming XENONnT experiment that can similarly be used to assess the sensitivity to arbitrary nuclear recoil signatures in its eventual 20 t-year exposure