1,818 research outputs found
Cosmology and Dark Matter at the LHC
We examine the question of whether neutralinos produced at the LHC can be
shown to be the particles making up the astronomically observed dark matter. If
the WIMP alllowed region lies in the SUGRA coannihilation region, then a strong
signal for this would be the unexpected near degeneracy of the stau and
neutralino i.e., a mass difference \Delta M\simeq (5-15) GeV. For the mSUGRA
model we show such a small mass difference can be measured at the LHC using the
signal 3\tau+jet+E_T^{\rm miss}. Two observables, opposite sign minus like sign
pairs and the peak of the \tau\tau mass distribution allows the simultaneous
determination of \Delta M to 15% and the gluino mass M_{\tilde g} to be 6% at
the benchmark point of M_{\tilde g}=850 GeV, A_0=0, \mu>0 with 30 fb^{-1}. With
10 fb^{-1}, \Delta M can be determined to 22% and one can probe the parameter
space up to m_{1/2}=700 GeV with 100 fb^{-1}.Comment: 11 pages, 7 figures, Talk at IDM 2006, 11th September to 16th
September, Greec
Detection of SUSY Signals in Stau Neutralino Co-annihilation Region at the LHC
We study the prospects of detecting the signal in the stau neutralino
co-annihilation region at the LHC using tau leptons. The co-annihilation signal
is characterized by the stau and neutralino mass difference (dM) to be 5-15 GeV
to be consistent with the WMAP measurement of the cold dark matter relic
density as well as all other experimental bounds within the minimal
supergravity model. Focusing on tau's from neutralino_2 --> tau stau --> tau
tau neutralino_1 decays in gluino and squark production, we consider inclusive
MET+jet+3tau production, with two tau's above a high E_T threshold and a third
tau above a lower threshold. Two observables, the number of opposite-signed tau
pairs minus the number of like-signed tau pairs and the peak position of the
di-tau invariant mass distribution, allow for the simultaneous determination of
dM and M_gluino. For dM = 9 GeV and M_gluino = 850 GeV with 30 fb^-1 of data,
we can measure dM to 15% and M_gluino to 6%.Comment: 4 pages LaTex, 3 figures. To appear in Proceedings of SUSY06, the
14th International Conference on Supersymmetry and the Unification of
Fundamental Interactions, UC Irvine, California, 12-17 June 2006. A typo in a
reference is correcte
The NOνA simulation chain
The NOνA experiment is a two-detector, long-baseline neutrino experiment operating in the recently upgraded NuMI muon neutrino beam. Simulating neutrino interactions and backgrounds requires many steps including: the simulation of the neutrino beam flux using FLUKA and the FLUGG interface; cosmic ray generation using CRY; neutrino interaction modeling using GENIE; and a simulation of the energy deposited in the detector using GEANT4. To shorten generation time, the modeling of detector-specific aspects, such as photon transport, detector and electronics noise, and readout electronics, employs custom, parameterized simulation applications. We will describe the NOνA simulation chain, and present details on the techniques used in modeling photon transport near the ends of cells, and in developing a novel data-driven noise simulation. Due to the high intensity of the NuMI beam, the Near Detector samples a high rate of muons originating in the surrounding rock. In addition, due to its location on the surface at Ash River, MN, the Far Detector collects a large rate (˜ 140 kHz) of cosmic muons. We will discuss the methods used in NOνA for overlaying rock muons and cosmic ray muons with simulated neutrino interactions and show how realistically the final simulation reproduces the preliminary NOνA data
Graph Neural Networks for Particle Reconstruction in High Energy Physics detectors
Pattern recognition problems in high energy physics are notably different
from traditional machine learning applications in computer vision.
Reconstruction algorithms identify and measure the kinematic properties of
particles produced in high energy collisions and recorded with complex detector
systems. Two critical applications are the reconstruction of charged particle
trajectories in tracking detectors and the reconstruction of particle showers
in calorimeters. These two problems have unique challenges and characteristics,
but both have high dimensionality, high degree of sparsity, and complex
geometric layouts. Graph Neural Networks (GNNs) are a relatively new class of
deep learning architectures which can deal with such data effectively, allowing
scientists to incorporate domain knowledge in a graph structure and learn
powerful representations leveraging that structure to identify patterns of
interest. In this work we demonstrate the applicability of GNNs to these two
diverse particle reconstruction problems.Comment: Presented at NeurIPS 2019 Workshop "Machine Learning and the Physical
Sciences
Graph Neural Networks for Particle Reconstruction in High Energy Physics detectors
Pattern recognition problems in high energy physics are notably different
from traditional machine learning applications in computer vision.
Reconstruction algorithms identify and measure the kinematic properties of
particles produced in high energy collisions and recorded with complex detector
systems. Two critical applications are the reconstruction of charged particle
trajectories in tracking detectors and the reconstruction of particle showers
in calorimeters. These two problems have unique challenges and characteristics,
but both have high dimensionality, high degree of sparsity, and complex
geometric layouts. Graph Neural Networks (GNNs) are a relatively new class of
deep learning architectures which can deal with such data effectively, allowing
scientists to incorporate domain knowledge in a graph structure and learn
powerful representations leveraging that structure to identify patterns of
interest. In this work we demonstrate the applicability of GNNs to these two
diverse particle reconstruction problems
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