2,462 research outputs found
Measuring spin and CP from semi-hadronic ZZ decays using jet substructure
We apply novel jet techniques to investigate the spin and CP quantum numbers
of a heavy resonance X, singly produced in pp -> X -> ZZ -> l(+)l(-)jj at the
LHC. We take into account all dominant background processes to show that this
channel, which has been considered unobservable until now, can qualify under
realistic conditions to supplement measurements of the purely leptonic decay
channels X -> ZZ -> 4l. We perform a detailed investigation of spin- and
CP-sensitive angular observables on the fully-simulated final state for various
spin and CP quantum numbers of the state X, tracing how potential sensitivity
communicates through all the steps of a subjet analysis. This allows us to
elaborate on the prospects and limitations of performing such measurements with
the semihadronic final state. We find our analysis particularly sensitive to a
CP-even or CP-odd scalar resonance, while, for tensorial and vectorial
resonances, discriminative features are diminished in the boosted kinematical
regime.Comment: 12 pages, 7 figures, 2 tables, published versio
Propagation of Ultra High Energy Cosmic Rays in Extragalactic Magnetic Fields: A view from cosmological simulations
We use the CRPropa code to simulate the propagation of ultra high energy
cosmic rays (with energy and pure proton composition)
through extragalactic magnetic fields that have been simulated with the
cosmological ENZO code.We test both primordial and astrophysical magnetogenesis
scenarios in order to investigate the impact of different magnetic field
strengths in clusters, filaments and voids on the deflection of cosmic rays
propagating across cosmological distances. We also study the effect of
different source distributions of cosmic rays around simulated Milky-Way like
observers. Our analysis shows that the arrival spectra and anisotropy of events
are rather insensitive to the distribution of extragalactic magnetic fields,
while they are more affected by the clustering of sources within a
Mpc distance to observers. Finally, we find that in order to reproduce the
observed degree of isotropy of cosmic rays at EeV energies, the average
magnetic fields in cosmic voids must be , providing limits
on the strength of primordial seed fields.Comment: 13 pages, 20 figure
Language and Meter
In Language and Meter, Dieter Gunkel and Olav Hackstein unite fifteen linguistic studies on a variety of poetic traditions, including the Homeric epics, the hieratic hymns of the Ṛgveda, the Gathas of the Avesta, early Latin and the Sabellic compositions, Germanic alliterative verse, Insular Celtic court poetry, and Tocharian metrical texts. The studies treat a broad range of topics, including the prehistory of the hexameter, the nature of Homeric formulae, the structure of Vedic verse, rhythm in the Gathas, and the relationship between Germanic and Celtic poetic traditions. The volume contributes to our understanding of the relationship between language and poetic form, and how they change over time.https://scholarship.richmond.edu/bookshelf/1318/thumbnail.jp
Introduction
The present volume unites fifteen studies on language and meter. For the most part, the articles began as lectures delivered during the interdisciplinary conference on Language and Meter in Diachrony and Synchrony, which was hosted in Munich from September 2nd-4th, 2013 by the Department of Historical and Indo-European Linguistics at the Ludwig-Maximilians-Universität München. The study of language and meter has profited from numerous advances over the last several hundred years. Scholars have produced accurate editions of poetic texts, added linguistic theory to description, utilized quantitative methods to test hypotheses, and provided descriptions and analyses of a relatively broad range of metrical traditions. To quote an influential handbook article on meter (Brogan 1993: 781), Linguistics, texts, theory, and data- these are the essential preliminaries. At the turn of the 21st c., pretty much everything still remains to be done. In our view, the contributions to this volume make a respectable amount of headway on numerous fronts. In the following overview, we intend to give a sense of the breadth of topics and traditions treated in the contributions as well as their relationship to previous scholarship
Sharpening up Galactic all-sky maps with complementary data - A machine learning approach
Galactic all-sky maps at very disparate frequencies, like in the radio and
-ray regime, show similar morphological structures. This mutual
information reflects the imprint of the various physical components of the
interstellar medium. We want to use multifrequency all-sky observations to test
resolution improvement and restoration of unobserved areas for maps in certain
frequency ranges. For this we aim to reconstruct or predict from sets of other
maps all-sky maps that, in their original form, lack a high resolution compared
to other available all-sky surveys or are incomplete in their spatial coverage.
Additionally, we want to investigate the commonalities and differences that the
ISM components exhibit over the electromagnetic spectrum. We build an
-dimensional representation of the joint pixel-brightness distribution of
maps using a Gaussian mixture model and see how predictive it is: How well
can one map be reproduced based on subsets of other maps? Tests with mock data
show that reconstructing the map of a certain frequency from other frequency
regimes works astonishingly well, predicting reliably small-scale details well
below the spatial resolution of the initially learned map. Applied to the
observed multifrequency data sets of the Milky Way this technique is able to
improve the resolution of, e.g., the low-resolution Fermi LAT maps as well as
to recover the sky from artifact-contaminated data like the ROSAT 0.855 keV
map. The predicted maps generally show less imaging artifacts compared to the
original ones. A comparison of predicted and original maps highlights
surprising structures, imaging artifacts (fortunately not reproduced in the
prediction), and features genuine to the respective frequency range that are
not present at other frequency bands. We discuss limitations of this machine
learning approach and ideas how to overcome them
MAITs and their mates: "Innate-like" behaviors in conventional and unconventional T cells
Most CD4 and CD8 T cells are restricted by conventional major histocompatibility complex (MHC) molecules and mount TCR-dependent adaptive immune responses. In contrast, MAIT, iNKT, and certain γδ TCR bearing cells are characterized by their abilities to recognize antigens presented by unconventional antigen-presenting molecules and to mount cytokine-mediated TCR-independent responses in an "innate-like" manner. In addition, several more diverse T-cell subsets have been described that in a similar manner are restricted by unconventional antigen-presenting molecules but mainly depend on their TCRs for activation. Vice versa, innate-like behaviour was reported in defined subpopulations of conventional T cells, particularly in barrier sites, showing that these two features are not necessarily linked. The abilities to recognize antigens presented by unconventional antigen-presenting molecules or to mount TCR-independent responses creates unique niches for these T cells and is linked to wide range of functional capabilities. This is especially exemplified by unconventional and innate-like T cells present at barrier sites where they are involved in pathogen defense, tissue homeostasis as well as in pathologic processes
Boosting Higgs discovery - the forgotten channel
Searches for a heavy Standard Model Higgs boson focus on the 'gold plated
mode' where the Higgs decays to two leptonic Z bosons. This channel provides a
clean signature, in spite of the small leptonic branching ratios. We show that
using fat jets the semi-leptonic ZZ mode significantly increases the number of
signal events with a similar statistical significance as the leptonic mode.Comment: 12 pages, 3 figure
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