Hunt For New Phenomena Using Large Jet Multiplicities And Missing Transverse Momentum With Atlas In 4 7 Fb 1 Of Sqrt S
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Phenomena Beyond The Standard Model What Do We Expect For New Physics To Look Like
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Author : Roman Pasechnik
language : en
Publisher: Frontiers Media SA
Release Date : 2020-09-03
Phenomena Beyond The Standard Model What Do We Expect For New Physics To Look Like written by Roman Pasechnik and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-09-03 with Science categories.
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Search For New Phenomena In Tt Events With Large Missing Transverse Momentum
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Author :
language : en
Publisher:
Release Date : 2014
Search For New Phenomena In Tt Events With Large Missing Transverse Momentum written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The ATLAS Run I data as provided by CERN's LHC has been systematically searched for the presence of supersymmetric partners of the top quark (stops) using the identification of charm-flavored jets and boosted top tagging. No signs of stop could be established yet.
Search For Squarks And Gluinos In Final States With Jets And Missing Transverse Momentum At S
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Author : Hannah Arnold
language : en
Publisher:
Release Date : 2016
Search For Squarks And Gluinos In Final States With Jets And Missing Transverse Momentum At S written by Hannah Arnold and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Abstract: A search for squarks and gluinos in final states containing hadronic jets, missing transverse momentum but no electrons or muons is presented. The data were recorded in 2015 by the ATLAS experiment in s√=13 TeV proton-proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 3.2 fb−1 of analyzed data. Results are interpreted within simplified models that assume R-parity is conserved and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95 % confidence level on the mass of the gluino is set at 1.51 TeV for a simplified model incorporating only a gluino octet and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.03 TeV are excluded for a massless lightest neutralino. These limits substantially extend the region of supersymmetric parameter space excluded by previous measurements with the ATLAS detector
Search For New Phenomena Using W Z B Jets Measurements Performed With The Atlas Detector
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Author :
language : en
Publisher:
Release Date : 2015
Search For New Phenomena Using W Z B Jets Measurements Performed With The Atlas Detector written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The Project proposed to use data of the ATLAS experiment, obtained during the 2011 and 2012 data-taking campaigns, to pursue studies of the strong interaction (QCD) and to examine promising signatures for new physics. The Project also contains a service component dedicated to a detector development initiative. The objective of the strong interaction studies is to determine how various predictions from the main theory (QCD) compare to the data. Results of a set of measurements developed by the Tufts team indicate that the dominant factor of discrepancy between data and QCD predictions come from the mis-modeling of the low energy gluon radiation as described by algorithms called parton showers. The discrepancies introduced by parton showers on LHC predictions could even be larger than the effect due to completely new phenomena (dark matter, supersymmetry, etc.) and could thus block further discoveries at the LHC. Some of the results obtained in the course of this Project also specify how QCD predictions must be improved in order to open the possibility for the discovery of something completely new at the LHC during Run-II. This has been integrated in the Run-II ATLAS physics program. Another objective of Tufts studies of the strong interaction was to determine how the hypothesis about an intrinsic heavy-quark component of the proton (strange, charm or bottom quarks) could be tested at the LHC. This hypothesis has been proposed by theorists 30 years ago and is still controversial. The Tufts team demonstrated that intrinsic charms can be observed, or severely constrained, at the LHC, and determine how the measurement should be performed in order to maximize its sensitivity to such an intrinsic heavy-quark component of the proton. Tufts also embarked on performing the measurement that is in progress, but final results are not yet available. They should shade a light of understanding on the fundamental structure of the proton. Determining the nature of dark matter particles, composing about 25% of all the matter in the universe, is one of the most exciting research goals at the LHC. Within this Project, the Tufts team proposed a way to improve over the standard approach used to look for dark matter at the LHC in events involving jets and a large amount of unbalanced energy in the detector (jets+ETmiss). The Tufts team has developed a measurement to test these improvements on data available (ATLAS 2012 dataset), in order to be ready to apply them on the new Run-II data that will be available at the end of 2015. Preliminary results on the proposed measurement indicate that a very high precision can be obtained on results free of detector effects. That will allow for better constrains of dark matter theories and will spare the needs for huge computing resources in order to compare dark matter theories to data. Finally, the Tufts team played a leading role in the development and the organization of the 6Et trigger, the detector component needed to collect the data used in dark matter searches and in many other analyses. The team compared the performance of the various algorithms capable of reconstructing the value of the ETmiss on each LHC collision event, and developed a strategy to commission these algorithms online. Tufts also contributed in the development of the ETmiss trigger monitoring software. Finally, the PI of this Project acted as the co-coordinator of the group of researchers at CERN taking care of the development and the operation of this detector component. The ETmiss trigger is now taking data, opening the possibility for the discovery of otherwise undetectable particles at the LHC.
Search For New Physics With The Mt2 Variable In All Jets Final States Produced In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Search For New Physics With The Mt2 Variable In All Jets Final States Produced In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
A search for new physics is performed using events that contain one or more jets, no isolated leptons, and a large transverse momentum imbalance, as measured through the MT2 variable, which is an extension of the transverse mass in events with two invisible particles. The results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and that corresponds to an integrated luminosity of 2.3 inverse femtobarns. The observed event yields in the data are consistent with predictions for the standard model backgrounds. The results are interpreted using simplified models of supersymmetry and are expressed in terms of limits on the masses of potential new colored particles. Assuming that the lightest neutralino is stable and has a mass less than about 500 GeV, gluino masses up to 1550-1750 GeV are excluded at 95% confidence level, depending on the gluino decay mechanism. For the scenario of direct production of squark-antisquark pairs, top squarks with masses up to 800 GeV are excluded, assuming a 100% branching fraction for the decay to a top quark and neutralino. Similarly, bottom squark masses are excluded up to 880 GeV, and masses of light-flavor squarks are excluded up to 600-1260 GeV, depending on the degree of degeneracy of the squark masses.
Search For Universal Extra Dimensions In The Two Photon And Missing Transverse Energy Final State With The Atlas Detector
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Author : Baharak Fatholahzadeh
language : en
Publisher:
Release Date : 2012
Search For Universal Extra Dimensions In The Two Photon And Missing Transverse Energy Final State With The Atlas Detector written by Baharak Fatholahzadeh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Measuring The Standard Model And Searching For New Physics With Jet Substructure Using The Atlas Detector
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Author : Maximilian Swiatlowski
language : en
Publisher:
Release Date : 2015
Measuring The Standard Model And Searching For New Physics With Jet Substructure Using The Atlas Detector written by Maximilian Swiatlowski and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Collisions at the Large Hadron Collider have offered an unprecedented window into some of the highest energy scales ever observed in experiments. Understanding these collisions, especially those that produce particles charged under quantum chromodynamics (QCD), requires a deep understanding of jets: the collimated sprays of particles produced by the parton shower and hadronization processes which emerge from the asymptotic freedom of QCD. Recent theoretical advances and the unprecedented capabilities of the ATLAS detector have enabled a new class of jet physics measurements based on the internal structure of jets, referred to as jet substructure. Three new types of measurements relying on jet substructure are presented. The first is a set of measurements sensitive which can discriminate between jets initiated by quarks and gluons. Separation is possible by studying variables sensitive to the magnitude of the color charge. Several such variables are measured, and a data-driven technique is used to construct a tagger, the first of its kind at a hadron collider, which can improve the sensitivity of searches for new physics in hadronic final states. A second measurement studies the color connections of jets in top-antitop events using an observable called the jet pull angle: sensitivity to the color representation of particles decaying to dijet pairs at a hadron collider is demonstrated for the first time. A final analysis searches for R-parity violating supersymmetry (SUSY) in all hadronic final states. These classes of models remove the characteristic missing energy signature which existing SUSY searches rely on, and require new discrimination techniques. Jet substructure provides a powerful handle to analyze these very high multiplicity states using a variable called the total jet mass. No signal is observed over the Standard Model (SM) prediction, and new limits are set on these previously unexplored models. The techniques of jet substructure lie at the hearts of all of these analyses, enabling both new measurements of SM phenomena and entirely new searches for physics beyond the SM.
Recent Results From The Search For New Phenomena At
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Author :
language : en
Publisher:
Release Date : 2001
Recent Results From The Search For New Phenomena At written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
We present results from several new searches for physics beyond the Standard Model. We describe a search based on the scalar sum of the transverse energy of the event, a global quantity nearly independent of the event topology. We summarize our searches for first generation leptoquarks into all three decay channels, eq[ovr eq], eq[ovr[nu]q], and[nu]q[ovr[nu]q] and note that this is the first time that the triumvirate of decay channels has been searched. We do not find any evidence for production of first generation leptoquarks and set a lower limit on the mass of the leptoquark of 175 GeV/c[sup 2], assuming the decay is exclusively into eq[ovr eq]. We also present results from the first search for a third generation leptoquark with charge[+-]1/3. Again, we find no evidence for its existence for a mass less than 80 GeV/c[sup 2] Finally, we discuss one of our searches for supersymmetry, specifically the pair-production of[tilde e], [tilde[nu]], and[tilde[chi]][sup 0][sub 2] where the decay yields final states with two photons plus missing transverse energy (E[sub T]). We set limits on the production cross section ranging from 1 pb to 400 fb, depending on the mass. This analysis also sets a model-independent limit of[sigma][center-dot] B(pp -[gamma][gamma][vert-bar] E[sub T][vert-bar] X)185 fb at the 95% CL for E[sub T][sup ([gamma])] 12 GeV and[vert-bar][eta][vert-bar]1.1 T and E[sub T] 25 GeV.
Applying Anomaly Detection To Search For New Physics With The Atlas Detector At The Large Hadron Collider
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Author : Alan Kahn
language : en
Publisher:
Release Date : 2022
Applying Anomaly Detection To Search For New Physics With The Atlas Detector At The Large Hadron Collider written by Alan Kahn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
A search for a heavy new particle Y decaying to a Standard Model Higgs boson H and another new particle X is presented. The search is performed using 139 fb−1 of p−p collision data at √s = 13 TeV recorded by the ATLAS detector. The H boson is identified through its decays to bb, with the only assumption applied to X being that it decays hadronically. The X is identified through a novel anomaly detection method via the use of a Variational Recurrent Neural Network trained directly on data collected by the ATLAS detector. This effort marks the first application of a fully unsupervised machine learning method to an ATLAS analysis. An additional benchmark based on interpreting the Y → XH process in the context of a heavy vector triplet model in which the X decays to two quarks defines an additional signal region in which upper limits on the HVT process cross section are reported at 95% confidence level.
Searches For New Physics Using Jets With The Atlas Detector
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Author : Aviv Ruben Cukierman
language : en
Publisher:
Release Date : 2020
Searches For New Physics Using Jets With The Atlas Detector written by Aviv Ruben Cukierman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The Large Hadron Collider produces particle collisions at the highest energies ever observed in a scientific experiment. This apparatus is built to test the predictions of the Standard Model of Particle Physics, including the existence and properties of the Higgs boson. As a proton-proton collider, quarks and gluons are produced in abundance, which quickly fragment and hadronize into collimated showers of energy called jets. These jets are detected and measured in the ATLAS detector, which is built around the point of the proton-proton collisions to observe the products of these interactions. Three major original research efforts are presented using data from proton-proton collisions observed in ATLAS. The first analyzes events with jets and photons to search for a beyond-the-Standard-Model decay of the Higgs boson. The second utilizes novel techniques in weak supervision to perform a generic data-driven resonance search in events with two jets. The third formalizes the calibration of the jet energies observed in the ATLAS detector, and further proposes a new method to improve this calibration with machine learning. The work presented here addresses some of the key questions in particle physics today. By searching for new physics, it is possible to shed light on the nature of the Higgs boson and the possibility of physics beyond the Standard Model. These searches focus on processes involving multiple jets in the final state, which motivates innovations in the reconstruction of jet energies. In addition to setting new bounds on theoretically interesting models, the innovations in object reconstruction and analysis techniques developed in this work can be applied in other ATLAS efforts using currently available data or data gathered in the future.