NYU Experimental Particle Physics Group

NYU participation in ATLAS

The NYU group became an official member of ATLAS in July of 2006. We are very active in the collaboration. Below is a brief description of our major activities.


First Beam!

On September 10, ATLAS saw its first beam from the LHC. ATLAS saw the first few events from the beam commissioning (not yet true collisions) on that day. You can see some event displays of those first collisions here. The startup of the LHC was going fairly well, until there was an incident on September 19. For more information, see an article in symmetry breaking here. It is expected that the LHC will start back up in late spring of 2009.


Higgs Searches

Professor Cranmer has been active in ATLAS Higgs searches for several years, focusing primarily on low-mass Higgs searches through the Vector Boson Fusion (VBF) mechanism. The low-mass range is preferred by precision electro-weak measurements and supersymmetric scenarios. In particular, Higgs decaying to tau leptons is a promising channel. Cranmer is the convenor of the US-ATLAS Higgs analysis forum. Akira Shibata and two prospective graduate students, George Lewis and Jordan Ziegler, are joining the effort. We also keep close contact with our theorist colleagues in the CCPP about non-standard Higgs models.


Triggering

The NYU group is working on the Missing Transverse Energy (MET) part of the High Level Trigger (HLT). MET, which measures an imbalance of momentum in the plane transverse to the particle collision, is sensitive to production of particles that don't interact in the detector. It is therefore a vital part of the search for new physics, and is a natural trigger component for us to study given our group's interest in the search for supersymmetry. Some of the possible sources of fake MET include mismeasurement of jet energies in QCD jet events, detector cracks, and beam-halo interactions. As these can be many orders of magnitude more frequent than SUSY events, they put severe constraints on the MET trigger. Kyle Cranmer and Diego Casadei are the co-coordinators of the ATLAS MET trigger "slice"; Allen Mincer and Rashid Djilkibaev are active developers of the triger algorithms; and Allen Mincer, Peter Nemethy and Long Zhao are active in validation of the trigger algorithms and understanding the trigger performance.


Supersymmetry

Supersymmetry (SUSY) is one of the most well-motivated and well-developed scenarios for physics beyond the standard model. If SUSY is the solution to the hierarchy problem, then it is very likely that we will see SUSY particles at the LHC. In R-parity conserving SUSY models, decays of SUSY particles always end with the Lightest Supersymmetric Particle (LSP), which is stable and weakly interacting. Thus, the LSP provides a natural candidate for dark matter. While the LSP would escape ATLAS undetected, it would leave a signature in Missing Transverse Energy (MET). This provides a strong link between our groups interest in SUSY and our work on MET triggers. If we are lucky enough to discovery SUSY at the LHC, the next challenge will be measuring the properties of the particles and unravling the many potential SUSY scenarios. Rostislav Konoplich and Rashid Djilkibaev are actively developing a novel mass measurement strategy, which promises competative measurements with a fraction of the data.


The ATLAS Analysis Model and EventView

The LHC experiments will produce an unprecidented amount of data, which poses a significant computing challenge. The ability to quickly and felxibly analyse those data is critical to the success of the ATLAS collaboration. NYU plays a major role in the development of the ATLAS Analysis Model. Kyle Cranmer was the original developer for many of the classes which are used to store the ATLAS data (eg. the AOD and ESD) and is the physics analysis tools group representative on ATLAS's Event Data Model committee and the Architecture-team.

EventView is an analysis framework originally developed by Kyle Cranmer, Akira Shibata, and Amir Farbin (U. Texas-Arlington). The EventView framework works within ATHENA (the ATLAS software environment) and promotes a model that facilitates the sharing of analysis code throughout the collaboration. It has been tremendously successful within ATLAS, hundreds of users and a growing developer community.

In addition to contributions to the data format and physics analysis tools, the NYU group also plays an important role in integrating the various components into a cohesive "analysis model". In particular, this means integration and testing with Grid computing (like PanDa) and the ROOT environment.


Statistical Methods for Particle Physics

Statistics plays an important role in science, and particularly in particle physics. Taking full advantage of the data, while properly incorporating systematic errors is a difficult task and often involves combining several sources of data in a complicated statistical model. In addition to important formal developments by our group (see links below), Kyle Cranmer is on the steering committee of the Phystat.org and an appointed member of the ATLAS statistics committee. He and Rene Brun have initiated the RooStats project -- a suite of high-level statistical tools in ROOT built on top of RooFit. It has already been demonstraited that one can digitially publish a full likelihood model, together with the relevant data, in order to statistically combine multiple measurements or perform multi-dimensional parameter scans.


LHC Upgrade

While the LHC is just starting, we are already thinking about an LHC upgrade: the Super-LHC. The Super-LHC would use the same tunnel that exists at CERN now, but it would have 10 times the luminosity. This extremely high luminosity environment poses several detector, triggering, and data acquisition challenges. Allen Mincer, Chris Musso, and Peter Nemethy are collaborating with Brookhaven National Lab in the development of one part of a new inner-detector, focusing on aspects of the support structure, supply of power, cooling, and tests of performance.


Previous Contributions

The NYU group became an official member of ATLAS in July of 2006. However, we did have some brief ATLAS participation in the past.



last updated Sat Dec 10 17:13:42 EST 2011