709 research outputs found
Constraining new resonant physics with top spin polarisation information
We provide a comprehensive analysis of the power of including top
quark-polarisation information to kinematically challenging resonance
searches, for which ATLAS and CMS start losing sensitivity. Following the
general modeling and analysis strategies pursued by the experiments, we analyse
the semi-leptonic and the di-lepton channels and show that including
polarisation information can lead to large improvements in the limit setting
procedures with large data sets. This will allow us to set limits for parameter
choices where sensitivity from is not sufficient. This highlights
the importance of spin observables as part of a more comprehensive set of
observables to gain sensitivity to BSM resonance searches.Comment: 13 pages, 11 figure
A global fit of top quark effective theory to data
In this paper we present a global fit of beyond the Standard Model (BSM)
dimension six operators relevant to the top quark sector to currently available
data. Experimental measurements include parton-level top-pair and single top
production from the LHC and the Tevatron. Higher order QCD corrections are
modelled using differential and global K-factors, and we use novel fast-fitting
techniques developed in the context of Monte Carlo event generator tuning to
perform the fit. This allows us to provide new, fully correlated and
model-independent bounds on new physics effects in the top sector from the most
current direct hadron-collider measurements in light of the involved
theoretical and experimental systematics. As a by-product, our analysis
constitutes a proof-of-principle that fast fitting of theory to data is
possible in the top quark sector, and paves the way for a more detailed
analysis including top quark decays, detector corrections and precision
observables.Comment: Additional references and preprint code added. Minor error in
generation of plots fixed, no conclusions affecte
Results from TopFitter
We discuss a global fit of top quark BSM couplings, phrased in the
model-independent language of higher-dimensional effective operators, to the
currently available data from the LHC and Tevatron. We examine the interplay
between inclusive and differential measurements, and the complementarity of LHC
and Tevatron results. We conclude with a discussion of projections for
improvement over LHC Run II.Comment: 5 pages, 4 figures, proceedings of the 9th International Workshop on
the CKM Unitarity Triangle, 28 November - 3 December 2016, Tata Institute for
Fundamental Research (TIFR), Mumbai, Indi
Reconstructing singly produced top partners in decays to Wb
Fermionic top partners are a feature of many models of physics beyond the standard model. We propose a search strategy for single production of top partners focusing specifically on the dominant decay to Wb . The enormous background can be reduced by exploiting jet substructure to suppress top-pair production and by requiring a forward jet. This simple strategy is shown to produce a sensitive search for single top-partner production, in the context of composite Higgs models, that has competitive mass reach with existing experimental searches for top-partner-pair production at the 8 TeV LHC
Comparative gene prediction in human and mouse.
The completion of the sequencing of the mouse genome promises to help predict human genes with greater accuracy. While current ab initio gene prediction programs are remarkably sensitive (i.e., they predict at least a fragment of most genes), their specificity is often low, predicting a large number of false-positive genes in the human genome. Sequence conservation at the protein level with the mouse genome can help eliminate some of those false positives. Here we describe SGP2, a gene prediction program that combines ab initio gene prediction with TBLASTX searches between two genome sequences to provide both sensitive and specific gene predictions. The accuracy of SGP2 when used to predict genes by comparing the human and mouse genomes is assessed on a number of data sets, including single-gene data sets, the highly curated human chromosome 22 predictions, and entire genome predictions from ENSEMBL. Results indicate that SGP2 outperforms purely ab initio gene prediction methods. Results also indicate that SGP2 works about as well with 3x shotgun data as it does with fully assembled genomes. SGP2 provides a high enough specificity that its predictions can be experimentally verified at a reasonable cost. SGP2 was used to generate a complete set of gene predictions on both the human and mouse by comparing the genomes of these two species. Our results suggest that another few thousand human and mouse genes currently not in ENSEMBL are worth verifying experimentally
The PDF4LHC report on PDFs and LHC data: Results from Run I and preparation for Run II
The accurate determination of the Parton Distribution Functions (PDFs) of the
proton is an essential ingredient of the Large Hadron Collider (LHC) program.
PDF uncertainties impact a wide range of processes, from Higgs boson
characterisation and precision Standard Model measurements to New Physics
searches. A major recent development in modern PDF analyses has been to exploit
the wealth of new information contained in precision measurements from the LHC
Run I, as well as progress in tools and methods to include these data in PDF
fits. In this report we summarise the information that PDF-sensitive
measurements at the LHC have provided so far, and review the prospects for
further constraining PDFs with data from the recently started Run II. This
document aims to provide useful input to the LHC collaborations to prioritise
their PDF-sensitive measurements at Run II, as well as a comprehensive
reference for the PDF-fitting collaborations.Comment: 55 pages, 13 figure
- …