Profile of multiboson signals

We investigate the visibility of signals characterised by wide bumps over a smoothly falling background that cannot be accurately predicted by Monte Carlo calculations. Examples of such are the wide bumps that triboson and quadriboson resonance cascade decays would yield in diboson resonance searches in fully hadronic final states. We find that the sensitivity to triboson bumps is rather small: signals of a moderate size could be present in current data and yet remain unnoticed. For quadriboson cascade decays the signals can hardly be distinguished from the background in the current searches.Comment: LaTeX 17 pages. v2: fixed typos and comments added; journal versio

Direct optimisation of the discovery significance when training neural networks to search for new physics in particle colliders

We introduce two new loss functions designed to directly optimise the statistical significance of the expected number of signal events when training neural networks to classify events as signal or background in the scenario of a search for new physics at a particle collider. The loss functions are designed to directly maximise commonly used estimates of the statistical significance, $s/\sqrt{s+b}$, and the Asimov estimate, $Z_A$. We consider their use in a toy SUSY search with 30~fb$^{-1}$ of 14~TeV data collected at the LHC. In the case that the search for the SUSY model is dominated by systematic uncertainties, it is found that the loss function based on $Z_A$ can outperform the binary cross entropy in defining an optimal search region

Arthur C. Clarke - Prophet of the Space Age

Informally known as The Big Three, Arthur C. Clarke, Isaac Asimov, and Robert Heinlein were arguably the most famous science fiction writers of the latter half of the 20th century. Interestingly, they all knew each other, both professionally and personally; Clarke corresponded with the other two regularly for decades. He even had an informal agreement with Asimov, the Clarke-Asimov Treaty, that if asked, they agreed to say that Clarke was the better science fiction writer and Asimov the better science writer. But Clarke was much more than a science fiction writer - he was an engineer, a scientist, a futurist, a humanist, an explorer, and even an educator

Asymptotic formulae for likelihood-based tests of new physics

We describe likelihood-based statistical tests for use in high energy physics for the discovery of new phenomena and for construction of confidence intervals on model parameters. We focus on the properties of the test procedures that allow one to account for systematic uncertainties. Explicit formulae for the asymptotic distributions of test statistics are derived using results of Wilks and Wald. We motivate and justify the use of a representative data set, called the "Asimov data set", which provides a simple method to obtain the median experimental sensitivity of a search or measurement as well as fluctuations about this expectation.Comment: fixed typo in equations 75 & 7

Reassessing the sensitivity to leptonic CP violation

We address the validity of the usual procedure to determine the sensitivity of neutrino oscillation experiments to CP violation. An explicit calibration of the test statistic is performed through Monte Carlo simulations for several experimental setups. We find that significant deviations from a $\chi^2$ distribution with one degree of freedom occur for experimental setups with low sensitivity to $\delta$. In particular, when the allowed region to which $\delta$ is constrained at a given confidence level is comparable to the whole allowed range, the cyclic nature of the variable manifests and the premises of Wilk's theorem are violated. This leads to values of the test statistic significantly lower than a $\chi^2$ distribution at that confidence level. On the other hand, for facilities which can place better constraints on $\delta$ the cyclic nature of the variable is hidden and, as the potential of the facility improves, the values of the test statistics first become slightly higher than and then approach asymptotically a $\chi^2$ distribution. The role of sign degeneracies is also discussed.Comment: 14 pages, 5 figures, RevTeX4. The discussion of the results has been improved and considerably extended. Version accepted for publication in JHE

Determination of neutrino mass ordering in future 76^{76}Ge-based neutrinoless double-beta decay experiments

Motivated by recent intensive experimental efforts on searching for neutrinoless double-beta decays, we perform a detailed analysis of the physics potential of the experiments based on $^{76}\mathrm{Ge}$. Assuming no signals, current and future experiments could place a $90\%$ lower limit on the half life $T^{0\nu}_{1/2} \gtrsim 4\times 10^{26}~{\rm yr}$ and $T^{0\nu}_{1/2} \gtrsim 7\times 10^{27}~{\rm yr}$, respectively. Then, how to report an evidence for neutrinoless double-beta decays is addressed by following the Bayesian statistical approach. For the first time, we present a quantitative description of experimental power to distinguish between normal and inverted neutrino mass orderings. Taking an exposure of $10^{4}~{\rm kg}\cdot{\rm yr}$ and a background rate of $10^{-4}~{\rm counts}/({\rm keV}\cdot{\rm kg}\cdot{\rm yr})$, we find that a moderate evidence for normal neutrino mass ordering (i.e., with a Bayes factor ${\cal B}$ given by $\ln({\cal B}) \simeq 2.5$ or a probability about $92.3\%$ according to the Jeffreys scale) can be achieved if the true value of effective neutrino mass $m^{}_{\beta\beta}$ turns out to be below $0.01~{\rm eV}$.Comment: 16 pages, 7 figures, the Jeffreys scale used, more discussions added, to appear in Phys. Rev.

Stellar Wakes from Dark Matter Subhalos

We propose a novel method utilizing stellar kinematic data to detect low-mass substructure in the Milky Way's dark matter halo. By probing characteristic wakes that a passing dark matter subhalo leaves in the phase space distribution of ambient halo stars, we estimate sensitivities down to subhalo masses $\sim 10^7\,M_\odot$ or below. The detection of such subhalos would have implications for dark-matter and cosmological models that predict modifications to the halo-mass function at low halo masses. We develop an analytic formalism for describing the perturbed stellar phase-space distributions, and we demonstrate through simulations the ability to detect subhalos using the phase-space model and a likelihood framework. Our method complements existing methods for low-mass subhalo searches, such as searches for gaps in stellar streams, in that we can localize the positions and velocities of the subhalos today.Comment: 6 + 3 pages, 1 + 2 figures, code available at: https://github.com/bsafdi/stellarWake

Science Fiction Transhumanism: Exegesis of the Foundation saga by Isaac Asimov

Este artículo analiza varias de las corrientes transhumanistas, como el singularitarianismo, inmortalismo, posgenerismo y abolicionismo, en la saga de la Fundación de Isaac Asimov. Partiendo de los quince libros que conforman dicha saga, se examina la visión de Asimov sobre estas ideas, y muestra cómo las diferentes novelas tratan sus complejas implicaciones, ya que contrariamente a la interpretación más habitual, el autor fue mucho más allá de sus historias de robots al tratar temáticas transhumanistas.This article analyzes several transhumanist currents, like singularitarianism, immortalism, postgenderism and abolitionism, in the Foundation series of Isaac Asimov. On the basis of the 15 books that make up the saga, Asimov’s vision of these ideas is examined to show how these novels address their complex implications, because contrary to the usual interpretation, the author went far beyond his robot stories for dealing with transhumanist topics