A model independent safeguard for unbinned Likelihood

We present a universal method to include residual un-modeled background shape uncertainties in likelihood based statistical tests for high energy physics and astroparticle physics. This approach provides a simple and natural protection against mismodeling, thus lowering the chances of a false discovery or of an over constrained confidence interval, and allows a natural transition to unbinned space. Unbinned likelihood allows optimal usage of information for the data and the models, and enhances the sensitivity. We show that the asymptotic behavior of the test statistic can be regained in cases where the model fails to describe the true background behavior, and present 1D and 2D case studies for model-driven and data-driven background models. The resulting penalty on sensitivities follows the actual discrepancy between the data and the models, and is asymptotically reduced to zero with increasing knowledge

From Final Dark Matter Results and Background Shape Uncertainties in XENON100 to First Light in XENON1T

The quest to directly detect dark matter, in particular weakly interactive massive particles (WIMP), lead to a development of a plethora of detector technologies. Since 2007 dual-phase time-projection chambers exploiting liquid xenon performed superior to all other technologies at WIMP masses above a few GeV/c^2. Among them, the XENON100 experiment shows the longest measurement with a combined live time of 477 days. An analysis to probe spin independent and spin dependent WIMP interactions is presented in this thesis, setting an upper limit on the WIMP-nucleon spin independent cross section at 1.1×10−45 cm^2 for a 50 GeV/c^2 WIMP mass. Furthermore, potential improvements are identified in the conventional XENON100 analysis and the outlined solution allows to consider shape uncertainties of non-parametric probability density functions by means of a profile likelihood analysis. The applicability of the method is shown by constraining the WIMP model in an astrophysical independent approach with XENON100 data. Finally, performance tests of the Hamamatsu R11410-21 3” photomultiplier tubes (PMT) are presented which are employed in the next generation experiment XENON1T. First results from the commissioning of the XENON1T detector with respect to the PMT performance are shown with a special focus on the impact of light emitting tubes

Detection of 133^{133}Xe from the Fukushima nuclear power plant in the upper troposphere above Germany

After the accident in the Japanese Fukushima Dai-ichi nuclear power plant in March 2011 large amounts of radioactivity were released and distributed in the atmosphere. Among them were also radioactive noble gas isotopes which can be used as tracers to test global atmospheric circulation models. This work presents unique measurements of the radionuclide $^{133}$Xe from Fukushima in the upper troposphere above Germany. The measurements involve air sampling in a research jet aircraft followed by chromatographic xenon extraction and ultra-low background gas counting with miniaturized proportional counters. With this technique a detection limit of the order of 100 $^{133}$Xe atoms in litre-scale air samples (corresponding to about 100 mBq/m$^3$) is achievable. Our results provide proof that the $^{133}$Xe-rich ground level air layer from Fukushima was lifted up to the tropopause and distributed hemispherically. Moreover, comparisons with ground level air measurements indicate that the arrival of the radioactive plume at high altitude over Germany occurred several days before the ground level plume.Comment: 8 pages, 5 figure

Dynamical Semigroup Description of Coherent and Incoherent Particle-Matter Interaction

The meaning of statistical experiments with single microsystems in quantum mechanics is discussed and a general model in the framework of non-relativistic quantum field theory is proposed, to describe both coherent and incoherent interaction of a single microsystem with matter. Compactly developing the calculations with superoperators, it is shown that the introduction of a time scale, linked to irreversibility of the reduced dynamics, directly leads to a dynamical semigroup expressed in terms of quantities typical of scattering theory. Its generator consists of two terms, the first linked to a coherent wavelike behaviour, the second related to an interaction having a measuring character, possibly connected to events the microsystem produces propagating inside matter. In case these events breed a measurement, an explicit realization of some concepts of modern quantum mechanics ("effects" and "operations") arises. The relevance of this description to a recent debate questioning the validity of ordinary quantum mechanics to account for such experimental situations as, e.g., neutron-interferometry, is briefly discussed.Comment: 22 pages, latex, no figure

a retrospective analysis

Purpose: We looked for any predictive value of change in primary tumor and metastatic lymph node volumes after induction chemotherapy (IC) on oncologic outcome in head and neck squamous cell carcinoma (HNSCC). Methods: Nineteen patients with stage IVA/B HNSCC treated between 2004 and 2010 with at least one cycle of IC (docetaxel, cisplatin and 5-fluorouracil / TPF) and concomitant chemoradiotherapy (CRT) with cisplatin were retrospectively analyzed. Volumes were calculated separately for primary tumor (Vtm), lymph node metastases (Vln) and their sum (Vsum) on computed tomography (CT) images before and after IC. The effect of volumetric changes on locoregional failure (LRF), distant metastasis (DM) and overall survival (OS) was assessed. P values <0.05 were considered as statistically significant. Results: The median follow-up of surviving patients was 25 months (range: 10.7-83.3). The median number of cycles and duration of TPF was 3 (range: 1-4) and 44 days (range: 4-116), respectively. Empirical area under the curve (AUC) analyses for death, LRF and DM revealed optimal cut-off values of Vtm diminution (30.54%, AUC: 87%) and Vsum decrease (35.45%, AUC: 64.55%) only for OS (p <0.05). Among those, a reduction in Vsum more than 35.4% between pre- and post-IC was significantly correlated with better OS (100 vs 43% at 2 years, p <0.05). Conclusion: Volumetric shrinkage of the tumor load after IC assessed with CT seems to predict OS. The assessment of volumetric shrinkage upon IC might be used to decide whether to offer patients alternative strategies like palliative/de-intensified treatments or more aggressive combined modalities after IC

Optimization viewpoint on Kalman smoothing, with applications to robust and sparse estimation

In this paper, we present the optimization formulation of the Kalman filtering and smoothing problems, and use this perspective to develop a variety of extensions and applications. We first formulate classic Kalman smoothing as a least squares problem, highlight special structure, and show that the classic filtering and smoothing algorithms are equivalent to a particular algorithm for solving this problem. Once this equivalence is established, we present extensions of Kalman smoothing to systems with nonlinear process and measurement models, systems with linear and nonlinear inequality constraints, systems with outliers in the measurements or sudden changes in the state, and systems where the sparsity of the state sequence must be accounted for. All extensions preserve the computational efficiency of the classic algorithms, and most of the extensions are illustrated with numerical examples, which are part of an open source Kalman smoothing Matlab/Octave package.Comment: 46 pages, 11 figure

Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II: Spectroscopic and Environmental Analysis of Thorne-\.Zytkow Object and Super-AGB Star Candidates

In previous work we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne-\.Zytkow Objects (T\.ZOs, red supergiants with a neutron star cores) or super-AGB stars (the most massive stars that will not undergo core collapse). This population includes HV\,2112, a peculiar star previously considered in other works to be either a T\.ZO or high-mass AGB star. Here we continue this investigation, using the kinematic and radio environments and local star formation history of these stars to place constraints on the age of the progenitor systems and the presence of past supernovae. These stars are not associated with regions of recent star formation, and we find no evidence of past supernovae at their locations. Finally, we also assess the presence of heavy elements and lithium in their spectra compared to red supergiants. We find strong absorption in Li and s-process elements compared to RSGs in most of the sample, consistent with super-AGB nucleosynthesis, while HV\,2112 shows additional strong lines associated with T\.ZO nucleosynthesis. Coupled with our previous mass estimates, the results are consistent with the stars being massive (~4-6.5M$_{\odot}$) or super-AGB (~6.5-12M$_{\odot}$) stars in the thermally pulsing phase, providing crucial observations of the transition between low- and high-mass stellar populations. HV\,2112 is more ambiguous; it could either be a maximally massive sAGB star, or a T\.ZO if the minimum mass for stability extends down to <13 M$_\odot$.Comment: 32 pages, 10 figures, 7 tables, spectroscopic data available at https://zenodo.org/record/7058608, accepted to The Astrophysical Journa