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Register a new userStatistical criteria for possible indications of new physics in tritium $beta$-decay spectrum
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The method of quasi-optimal weights is applied to constructing (quasi-)optimal criteria for various anomalous contributions in experimental spectra. Anomalies in the spectra could indicate physics beyond the Standard Model (additional interactions and neutrino flavours, Lorenz violation etc.). In particular the cumulative tritium $beta$-decay spectrum (for instance, in Troitsk-$ u$-mass, Mainz Neutrino Mass and KATRIN experiments) is analysed using the derived special criteria. Using the power functions we show that the derived quasi-optimal criteria are efficient statistical instruments for detecting the anomalous contributions in the spectra.
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The objective of the Karlsruhe Tritium Neutrino (KATRIN) experiment is to determine the effective electron neutrino mass $m( u_text{e})$ with an unprecedented sensitivity of $0.2,text{eV}$ (90% C.L.) by precision electron spectroscopy close to the endpoint of the $beta$ decay of tritium. We present a consistent theoretical description of the $beta$ electron energy spectrum in the endpoint region, an accurate model of the apparatus response function, and the statistical approaches suited to interpret and analyze tritium $beta$ decay data observed with KATRIN with the envisaged precision. In addition to providing detailed analytical expressions for all formulae used in the presented model framework with the necessary detail of derivation, we discuss and quantify the impact of theoretical and experimental corrections on the measured $m( u_text{e})$. Finally, we outline the statistical methods for parameter inference and the construction of confidence intervals that are appropriate for a neutrino mass measurement with KATRIN. In this context, we briefly discuss the choice of the $beta$ energy analysis interval and the distribution of measuring time within that range.
The beta decay of tritium in the form of molecular TT is the basis of sensitive experiments to measure neutrino mass. The final-state electronic, vibrational, and rotational excitations modify the beta spectrum significantly, and are obtained from theory. We report measurements of the branching ratios to specific ionization states for the isotopolog HT. Two earlier, concordant measurements gave branching ratios of HT to the bound HHe$^+$ ion of 89.5% and 93.2%, in sharp disagreement with the theoretical prediction of 55-57%, raising concerns about the theorys reliability in neutrino mass experiments. Our result, 56.5(6)%, is compatible with the theoretical expectation and disagrees strongly with the previous measurements.
We consider tritium beta decay with additional emission of light pseudoscalar or vector bosons coupling to electrons or neutrinos. The electron energy spectrum for all cases is evaluated and shown to be well estimated by approximated analytical expressions. We give the statistical sensitivity of KATRIN to the mass and coupling of the new bosons, both in the standard setup of the experiment as well as for future modifications in which the full energy spectrum of tritium decay is accessible.
The statistical methods used in deriving physics results in the BaBar collaboration are reviewed, with especial emphasis on areas where practice is not uniform in particle physics.
Modern analysis of high energy physics (HEP) data needs advanced statistical tools to separate signal from background. A C++ package has been implemented to provide such tools for the HEP community. The package includes linear and quadratic discriminant analysis, decision trees, bump hunting (PRIM), boosting (AdaBoost), bagging and random forest algorithms, and interfaces to the standard backpropagation neural net and radial basis function neural net implemented in the Stuttgart Neural Network Simulator. Supplemental tools such as bootstrap, estimation of data moments, and a test of zero correlation between two variables with a joint elliptical distribution are also provided. The package offers a convenient set of tools for imposing requirements on input data and displaying output. Integrated in the BaBar computing environment, the package maintains a minimal set of external dependencies and therefore can be easily adapted to any other environment. It has been tested on many idealistic and realistic examples.
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