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The solution was to use the DaVinci cluster at Rice to generate the backgrounds by running up to 200 Pythia simulation runs at once. This process generated enough background for 12 t-tbar events and this served as our test set. Unfortunately signal-to-noise ratio in the test set was so low that the logistic regression algorithm in WEKA could not be trained against it – the resulting model failed to detect any t-tbar events at all. Also, training logistic regression on the full test set strained the memory capabilities of the Java virtual machine it was run on, leading to frequent crashes.

To get around this, the author decided to compromise and experiment with training the logistic regression classifier on much smaller training sets with differing ratios of t-tbar events to background events. The performance of the resulting models were then tested on the cross-validation set containing 10,000 of each type of event. The model generated from a training set with a ratio of tt-bar to background events of about 50 seemed to perform the best. (See Table TODO).


As a result of performing the above optimizations, the efficiency of the logistic regression model at analyzing the very large test set improved by over a factor of 30 while only halving the true positive rate, as shown in Table TODO. It is important to note that the false positive ratio is still much too high for top quarks to be discoverable with a data set of this size. Since we are dealing with counting statistics of independent events, the uncertainty in the background count is approximately the square root of the background count, corresponding to a standard deviation of about 13. Since our signal is only 6 t-tbar events, this means we have a signal significance of about 0 . 4 σ . In order to get a statistically significant result, we would need to collect around 150 times as much raw data.


We have demonstrated that we can optimize our use of linear regression to exploit characteristics of a particular particle physics data set. Existing tools like WEKA make using machine learning for this task relatively straightforward, with no need to reinvent the wheel.

It should be noted that this project has neglected the most difficult and computationally intensive part of identifying new physics with particle detectors: modeling the performance of the particle detectors themselves. Modern particle detectors are incredibly complicated pieces of machinery and modeling their capabilities (which change often as components are upgraded) requires a measurable fraction of the planet's computing resources. (ref Grid Computing)

Future work

Dr. Subramanian also suggested that classifier performance could be improved by combining several integer features, namely how many of each type of lepton were found in each event, into one category feature, namely which lepton type was found. This makes sense because the high-level trigger eliminates all events that do not have exactly one lepton. A simple script should be able to transform all of the existing data to make this possible.


WEKA PythiaParticle physics book

h t t p : / / w w w . r e a d w r i t e w e b . c o m / a r c h i v e s / c e r n o f f i c i a l l y u n v e i l s i t s g r . p h p


The author would like to thank Dr. Paul Padley and Dr. Devika Subramanian for providing advice and training for this project, as well as Dr. Andrew Ng for his excellent and fun on-line machine learning class.

Directions for using code

Install Pythia 8 and WEKA on your UNIX machine. The included scripts and Makefile assume that the WEKA classes are in /usr/share/java/weka.jar and that the directory containing the code and data files is located in the pythia directory. See the included README file for more details.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introductory survey and applications of machine learning methods. OpenStax CNX. Dec 22, 2011 Download for free at http://legacy.cnx.org/content/col11400/1.1
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