Search

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [https://publikationen.bibliothek.kit.edu/270060419] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [arXiv:1909.06048]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns., Comment: Added missing acknowledgement, corrected performance statement in chapter 4.2.5, updated author list and references

This paper reports on work to improve mass stability when transferring platinum/iridium, stainless steel and silicon artefacts between air and vacuum using inert gas (argon) as a transfer/storage medium. Work is underway to redefine the kilogram in terms of a fundamental constant of nature and this will involve realizing a kilogram in vacuum. The development of an effective traceability link to this kilogram in vacuum is therefore essential for dissemination of the mass scale in the future. The work reported here investigates the effect of cycling artefacts between air and vacuum compared with cycling artefacts between argon and vacuum. Additionally, the effect of transferring artefacts between short-term storage in air compared with short term-storage in argon is investigated. The results presented demonstrate improved stability in the artefacts that are transferred between storage in argon and vacuum compared with those that are transferred between storage in air and vacuum.

Neutrinoless double-beta decay is a uniquely sensitive probe of lepton number violating processes, and its observation may answer fundamental questions in neutrino physics, including the nature and the mass scale of the light neutrinos. Tracking calorimeter experiments have particular strengths, including the ability to search for neutrinoless double-beta decay amongst several different isotopes hosted in source foils. Full event reconstruction provides powerful background rejection capability, and the ability to disentangle different mechanisms for neutrinoless double-beta decay in the event of its discovery. These proceedings will give the latest results from the NEMO-3 experiment, including new double-beta decay measurements using the isotopes 48Ca and 150Nd. The current status and future prospects for the SuperNEMO experiment will also be presented.

Neutrino mass sum rules are an important class of predictions in flavour models relating the Majorana phases to the neutrino masses. This leads, for instance, to enormous restrictions on the effective mass as probed in experiments on neutrinoless double beta decay. While up to now these sum rules have in practically all cases been taken to hold exactly, we will go here beyond that. While the effect of the renormalisation group running can be visible, the qualitative features do not change. This changes somewhat for model dependent corrections which might alter even the qualitative predictions but only for large corrections and a high neutrino mass scale close to the edge of the current limits. This finding backs up the solidity of the predictions derived in the literature apart from some exceptions, and it thus marks a very important step in deriving testable and robust predictions from neutrino flavour models., Comment: 3 pages; proceedings of Neutrino 2016, XXVII International Conference on Neutrino Physics and Astrophysics, 4-9 July 2016, London, UK

To an ever increasing extent, weighing instruments for the determination of masses of more than 50 kg are designed as high-accuracy weighing instruments of accuracy class II rather than as medium accuracy weighing instruments of accuracy class III. Consequently, the masses required for testing must meet higher accuracy requirements. The uncertainty of a 5 t mass scale set up at the Physikalisch-Technische Bundesanstalt (PTB) is assessed on the basis of an analysis of the uncertainties which can be attained. This mass scale allows masses of 10 kg, 50 kg, 500 kg and 5 t to be calibrated with relative uncertainties of 5 × 10-8, 6 × 10-8, 3 × 10-7 and 1,5 × 10-7. With their aid, deadweights of up to 50 kN for force standard machines can be determined with relative uncertainties of 4 × 10-7.

We briefly review the main aspects of leptogenesis, describing both the unflavoured and the flavoured versions of the $N_2$-dominated scenario. A study of the success rates of both classes of models has been carried out. We comment on these results and discuss corrective effects to this simplest scenario. Focusing on the flavoured case, we consider the conditions required by strong thermal leptogenesis, where the final asymmetry is fully independent of the initial conditions. Barring strong cancellations in the seesaw formula and in the flavoured decay parameters, we show that strong thermal leptogenesis favours a lightest neutrino mass $m_1\gtrsim10\,\mbox{meV}$ for normal ordering (NO) and $m_1\gtrsim 3\,\mbox{meV}$ for inverted ordering (IO). Finally, we briefly comment on the power of absolute neutrino mass scale experiments to either support or severely corner strong thermal leptogenesis., Comment: Contribution to the Proceedings of the NuPhys2013 Conference: Prospects in Neutrino Physics, 19-20 December 2013, IOP, London

In the past few years there have been new developments in the effort of constraining neutrino properties with cosmology. The Cosmic Microwave Background has been measured with renewed and improved precision and large-scale structure surveys have mapped cosmological structures in the Universe over unprecedentedly large volumes. Future, massive large-scale structure surveys have been presented and approved. On the theory side, a significant effort has been devoted to achieve better modelling of small scale clustering and of cosmological non-linearities. As a result it has become clear that forthcoming cosmological data have, in principle, enough statistical power to detect the effect of non-zero neutrino mass (even at the lower mass scale limit imposed by oscillations) and to constrain the absolute neutrino mass scale. I will present some recent work on constraints on neutrino properties from cosmology, concentrating in particular on the work done by my group and my collaborators.

Series of short baseline neutrino oscillation experiments provided unexpected results, and now they are called short baseline anomalies, and all indicates an existence of sterile neutrinos with a mass scale around 1~eV. The signals of short baseline anomalies are reported from 4 different classes of experiments. However, at this moment, there is no convincing theoretical model to explain such sterile neutrinos, and a single experiment to confirm 1~eV sterile neutrinos may be challenging. In this short note, we describe classes of short baseline neutrino oscillation experiments and their goals., 8 pages, 1 figure, presented at "NuPhys2013 - prospects in neutrino physics", Institute of Physics, London, UK, Dec. 19-20, 2013

The LHC is constraining BSM physics at an impressive efficience, but no sign of new physics has been found yet. SUSY (and other BSM scenarios) are starting to be in trouble, though there is still room for new physics able to solve the Hierarchy Problem. This situation poses new challenges to optimize the LHC discovery potential using smarter strategies for analysis. In this sense, direct and indirect searches of new physics can play complementary roles.

We show that the No-Scale Flipped SU(5) construction is transparently consistent with recent LHCb results for B_s^0 to \mu^+ \mu^- decays, due primarily to suppression from the rather small value of tan\beta ~ 20 that is globally enforced across the model space. This fact should be interpreted in conjunction with the demonstrated evasion of mass limits from the ATLAS and CMS SUSY searches and the more important potential explanation of small observed excesses in the multijet data. The No-Scale Flipped SU(5) benchmark model that best fits these excesses has a gaugino mass scale of M_{1/2} = 708 GeV, which drives masses for the bino-dominated LSP m_\chi_1^0 = 143.4 GeV, light stop m_t1 = 786 GeV, gluino m_g = 952 GeV, and heavy squark m_uL = 1490 GeV. The corresponding total prediction for the rare B-decay of Br(B_s^0 to \mu^+ \mu^-) = 3.5 x 10^-9 suggests that the SUSY contribution may indeed be much smaller than that expected from the Standard Model in this framework, fitting quite comfortably within the very tightly constrained region remaining viable after the most recent LHCb measurements.

Analytic properties of Graham-Witten anomalies are considered. Weyl anomalies according to their analytic properties are of type A (coming from $\delta$-singularities in correlators of several energy-momentum tensors) or of type B (originating in counterterms which depend logarithmically on a mass scale). It is argued that all Graham-Witten anomalies can be divided into 2 groups: internal and external, and that all external anomalies are of type B, whereas among internal anomalies there is one term of type A and all the rest are of type B. This argument is checked explicitly for the case of a free scalar field in a 6-dimensional space with a 2-dimensional submanifold., Comment: 2 typos corrected

It is conjectured and shown by means of the screening Casimir effective couplings among fermions that, the four-fermion condensates formed through the SU(N) hypercolor gauge interactions, in general, may always have two forming paths which respectively correspond to different mass scales, and only for some special SU(N) representations of the fermions the condensates have one mass scale or no four-fermion condensate could be formed.