New edition of Eurachem/CITAC guide on measurement uncertainty arising from sampling

The second edition of the Eurachem/CITAC Guide on measurement uncertainty arising from sampling (UfS) has recently been published [1]. It has been updated to explain how several new research ideas can be used to improve the way that we estimate and express UfS. The Guide considers the whole measurement process, which usually begins at the point where a primary sample is taken. It retains the basic structure of the first edition, describing the estimation of UfS by both empirical and modelling approaches, and includes six worked examples across several application sectors, including food, animal feed, soil and water

Eurachem Workshop on ‘Uncertainty from Sampling and Analysis for Accredited Laboratories’: BAM, Berlin, 19-20 November 2019

The article reviews the Eurachem Workshop on ‘Uncertainty from sampling and analysis for accredited laboratories’, that was held in conjunction with Eurolab-Germany and CITAC, at BAM in Berlin on November 19th-20th 2019. This two-day Workshop attracted over 140 participants from 27 counties, who made 30 presentation, both orally and as posters. One of its objectives was to launch the Second Edition of the Eurachem/CITAC Guide on Measurement Uncertainty arising from Sampling. The first day was therefore mainly focused on UfS and several of the new ideas in this area that have been incorporated into the revised Guide. For example, the Uncertainty Factor was explained as a better way to express measurement uncertainty (U) when the values are large (e.g. U > 20%), and when the frequency distribution of the uncertainty is shown to be log-normal, rather than the Gaussian that is usually assumed. Some examples where given where this asymmetry in the uncertainty was seen to arise from the sampling process, but other examples arose from purely analytical sources, such as the determination of genetically modified organisms (GMOs) in soya

Chiral Symmetries and Low Energy Searches for New Physics

I discuss low energy searches for new physics beyond the Standard Model, identifying the role played by chiral symmetries in these searches and in various new physics scenarios. I focus in particular on electric dipole moment searches; precision studies of weak decays and electron scattering; and neutrino properties and interactions.Comment: Talk given at 5th International Workshop on Chiral Dynamics, Durham/Chapel Hill, NC (September, 2006); 12 page

Nuclei as Laboratories: Nuclear Tests of Fundamental Symmetries

The prospect of a rare isosotope accelerator facility opens up possibilities for a new generation of nuclear tests of fundamental symmetries. In this talk, I survey the current landscape of such tests and discuss future opportunities that a new facility might present.Comment: To appear in proceedings of 3rd ANL/MSU/INT/JINA Theory Workshop, Argonne National Laboratory (April, 2006); 13 page

Electric Dipole Moments: A Global Analysis

We perform a global analysis of searches for the permanent electric dipole moments (EDMs) of the neutron, neutral atoms, and molecules in terms of six leptonic, semileptonic, and nonleptonic interactions involving photons, electrons, pions, and nucleons. Translating the results into fundamental CP-violating effective interactions through dimension six involving Standard Model particles, we obtain rough lower bounds on the scale of beyond the Standard Model CP-violating interactions ranging from 1.5 TeV for the electron EDM to 1300 TeV for the nuclear spin-independent electron-quark interaction. We show that future measurements involving systems or combinations of systems with complementary sensitivities to the low-energy parameters may extend the mass reach by an order of magnitude or more.Comment: 15 pages, 1 figur

Top Down Electroweak Dipole Operators

We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark ($d_t$) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale $v$, the $d_t$ arises from two gauge invariant operators generated at a scale $\Lambda \gg v$ that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on $|d_t|$. Working in the leading log-squared approximation, we find that the present upper bound on $|d_t|$ is roughly $10^{-19}$ $e$ cm for $\Lambda = 1$ TeV, except in regions of finely tuned cancellations that allow for $|d_t|$ to be up to fifty times larger. Future $d_e$ and $d_n$ probes may yield an order of magnitude increase in $d_t$ sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.Comment: 7 pages, 6 figure

New Physics Effects in Higgs Decay to Tau Leptons

We study the possible effects of TeV scale new physics (NP) on the rate for Higgs boson decays to charged leptons, focusing on the tau tau channel which can be readily studied at the Large Hadron collider. Using an SU(3)_C X SU(2)_L X U(1)_Y invariant effective theory valid below a NP scale Lambda, we determine all effective operators up to dimension six that could generate appreciable contributions to the decay rate and compute the dependence of the rate on the corresponding operator coefficients. We bound the size of these operator coefficients based on the scale of the tau mass, naturalness considerations, and experimental constraints on the tau anomalous magnetic moment. These considerations imply that contributions to the decay rate from a NP scale Lambda ~ TeV could be comparable to the prediction based on the SM Yukawa interaction. A reliable test of the Higgs mechanism for fermion mass generation via the h-> tau tau channel is possible only after such NP effects are understood and brought under theoretical control.Comment: 10 pages, 6 figures, V2: typos correcte

Electron-to-Tau Lepton Flavor Violation at the Electron-Ion Collider

We analyze the potential sensitivity of a search for $e\rightarrow\tau$ conversion at a proposed electron-ion collider (EIC) facility. To that end, we calculate the cross sections for $e\rightarrow\tau$ events in a leptoquark framework assuming that the leptoquark masses are on the order of several hundred GeV or more. Given present limits on leptoquarks from direct searches at HERA and rare decay processes, an EIC sensitive to 0.1 fb $e\rightarrow\tau$ cross sections could probe previously unexplored regions of parameter space for these lepton flavor violating events (assuming 90 GeV center-of-mass energy and 10 fb$^{-1}$ integrated luminosity). Depending on the species of leptoquark and flavor structure of the couplings, an EIC search could surpass the HERA and rare process sensitivity to $e\rightarrow\tau$ conversion amplitudes by as much as an order of magnitude or more. We also derive updated limits on quark flavor-diagonal LFV leptoquark interactions using the most recent BaBar $\tau\rightarrow e\gamma$ search. We find that limits from an EIC $e\rightarrow\tau$ search could be competitive with the most recent $\tau\rightarrow e\gamma$ limit for a subset of the quark flavor-diagonal leptoquark couplings. Using an SU(5) GUT model in which leptoquark couplings are constrained by the neutrino masses and mixing, we illustrate how observable leptoquark-induced $e\rightarrow\tau$ conversion can be consistent with stringent LFV limits imposed by $\mu\rightarrow e\gamma$ and $\mu\rightarrow e$ conversion searches.Comment: 19 pages, 7 figure