2,783 research outputs found
Adversarially Learned Anomaly Detection on CMS Open Data: re-discovering the top quark
We apply an Adversarially Learned Anomaly Detection (ALAD) algorithm to the
problem of detecting new physics processes in proton-proton collisions at the
Large Hadron Collider. Anomaly detection based on ALAD matches performances
reached by Variational Autoencoders, with a substantial improvement in some
cases. Training the ALAD algorithm on 4.4 fb-1 of 8 TeV CMS Open Data, we show
how a data-driven anomaly detection and characterization would work in real
life, re-discovering the top quark by identifying the main features of the
t-tbar experimental signature at the LHC.Comment: 16 pages, 9 figure
Variational Autoencoders for New Physics Mining at the Large Hadron Collider
Using variational autoencoders trained on known physics processes, we develop
a one-sided threshold test to isolate previously unseen processes as outlier
events. Since the autoencoder training does not depend on any specific new
physics signature, the proposed procedure doesn't make specific assumptions on
the nature of new physics. An event selection based on this algorithm would be
complementary to classic LHC searches, typically based on model-dependent
hypothesis testing. Such an algorithm would deliver a list of anomalous events,
that the experimental collaborations could further scrutinize and even release
as a catalog, similarly to what is typically done in other scientific domains.
Event topologies repeating in this dataset could inspire new-physics model
building and new experimental searches. Running in the trigger system of the
LHC experiments, such an application could identify anomalous events that would
be otherwise lost, extending the scientific reach of the LHC.Comment: 29 pages, 12 figures, 5 table
Neural Computing for Event Log Quality Improvement
Department of Management EngineeringAn event log is a vital part used for process mining such as process discovery, conformance checking or enhancement. Like any other data, the initial event logs can be too coarse resulting in severe data mining mistakes. Traditional statistical reconstruction methods work poorly with event logs, because of the complex interrelations among attributes, events and cases. As such, machine learning approaches appear more suitable for reconstructing or repairing event logs. However, there is very limited work on exploiting neural networks to do this task.
This thesis focuses on two issues that may arise in the coarse event logs, incorrect attribute values and missing attribute values. We are interested in exploring the application of different kinds of autoencoders on the task of reconstructing event logs since this architecture suits the problem of unsupervised learning, such as the ones we are considering. When repairing an event log, in fact, one cannot assume that a training set with true labels is available for model training. We also propose the techniques for preprocessing and training the event logs data. In order to provide an insight on how feasible and applicable our work is, we have carried out experiments using real-life datasets.
Regarding the first issue, we train autoencoders under purely unsupervised manner to deal with the problem of anomaly detection without using any prior knowledge of the domain. We focus on developing algorithms that can capture the general pattern and sequence aspect of the data.
In order to solve the second issue, we develop models that should not only learn the representation and underlying true distribution of the data but also be able to generate the realistic and reliable output that has the characteristic of the logs.ope
Revealing Fundamental Physics from the Daya Bay Neutrino Experiment using Deep Neural Networks
Experiments in particle physics produce enormous quantities of data that must
be analyzed and interpreted by teams of physicists. This analysis is often
exploratory, where scientists are unable to enumerate the possible types of
signal prior to performing the experiment. Thus, tools for summarizing,
clustering, visualizing and classifying high-dimensional data are essential. In
this work, we show that meaningful physical content can be revealed by
transforming the raw data into a learned high-level representation using deep
neural networks, with measurements taken at the Daya Bay Neutrino Experiment as
a case study. We further show how convolutional deep neural networks can
provide an effective classification filter with greater than 97% accuracy
across different classes of physics events, significantly better than other
machine learning approaches
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