Advances in Jet Substructure at the LHC

Advances in Jet Substructure at the LHC
Author: Roman Kogler
Publisher: Springer Nature
Total Pages: 287
Release: 2021-05-10
Genre: Science
ISBN: 3030728587

Download Advances in Jet Substructure at the LHC Book in PDF, Epub and Kindle

This book introduces the reader to the field of jet substructure, starting from the basic considerations for capturing decays of boosted particles in individual jets, to explaining state-of-the-art techniques. Jet substructure methods have become ubiquitous in data analyses at the LHC, with diverse applications stemming from the abundance of jets in proton-proton collisions, the presence of pileup and multiple interactions, and the need to reconstruct and identify decays of highly-Lorentz boosted particles. The last decade has seen a vast increase in our knowledge of all aspects of the field, with a proliferation of new jet substructure algorithms, calculations and measurements which are presented in this book. Recent developments and algorithms are described and put into the larger experimental context. Their usefulness and application are shown in many demonstrative examples and the phenomenological and experimental effects influencing their performance are discussed. A comprehensive overview is given of measurements and searches for new phenomena performed by the ATLAS and CMS Collaborations. This book shows the impressive versatility of jet substructure methods at the LHC.

Search for Supersymmetry in Hadronic Final States with Missing Transverse Energy Using the Variables [alpha] T and B-quark Multiplicity in Pp Collisions at $\sqrt{s}

Search for Supersymmetry in Hadronic Final States with Missing Transverse Energy Using the Variables [alpha] T and B-quark Multiplicity in Pp Collisions at $\sqrt{s}
Author:
Publisher:
Total Pages: 45
Release: 2013
Genre:
ISBN:

Download Search for Supersymmetry in Hadronic Final States with Missing Transverse Energy Using the Variables [alpha] T and B-quark Multiplicity in Pp Collisions at $\sqrt{s} Book in PDF, Epub and Kindle

An inclusive search for supersymmetric processes that produce final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of 8 TeV. The data sample corresponds to an integrated luminosity of 11.7 fb-1 collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, [alpha] T, is used to discriminate between events with genuine and misreconstructed missing transverse energy. The search is based on an examination of the number of reconstructed jets per event, the scalar sum of transverse energies of these jets, and the number of these jets identified as originating from bottom quarks. No significant excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of simplified models, with a special emphasis on both compressed-spectrum scenarios and direct or gluino-induced production of third-generation squarks. For the case of gluino-mediated squark production, gluino masses up to 950-1125 GeV are excluded depending on the assumed model. Finally, for the direct pair-production of squarks, masses up to 450 GeV are excluded for a single light first- or second-generation squark, increasing to 600 GeV for bottom squarks.

Search for Supersymmetry in P-p Collisions at √s

Search for Supersymmetry in P-p Collisions at √s
Author: Kin Ho Lo
Publisher:
Total Pages: 152
Release: 2018
Genre:
ISBN:

Download Search for Supersymmetry in P-p Collisions at √s Book in PDF, Epub and Kindle

"The thesis describes a search for new physics in form of supersymmetry in hadronic final states and missing transverse energy (ET) using a dataset of 35.9 fb−1 collected during the 2016 proton-proton runs by the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The search uses robust kinematic variables to suppress backgrounds while maintaining good acceptance to a broad range of signal models and employs data-driven techniques to accurately determine backgrounds and systematic uncertainties. No evidence for Beyond Standard Model (BSM) physics is observed and simplified models are used to interpret the results. For gluino mediated models, the gluino mass up to 1850 GeV and the lightest symmetric particle (LSP) up to 1100 GeV are excluded. For light squark mediated models, the light squark mass up to 1350 GeV (700 GeV) and the LSP up to 650 GeV (400 GeV), assuming no degeneracy in the light squark masses (a degeneracy in light squark masses). For sbottom mediated models, the sbottom mass is excluded to 1075 GeV and the LSP mass up to 550 GeV. For stop mediated models, the stop mass is excluded up to 1075 GeV with the LSP mass up to 400 GeV."--Page x.

Search for Supersymmetry in the All-hadronic Final State Using Top Quark Tagging in Pp Collisions at Sqrt(s)

Search for Supersymmetry in the All-hadronic Final State Using Top Quark Tagging in Pp Collisions at Sqrt(s)
Author:
Publisher:
Total Pages:
Release: 2017
Genre:
ISBN:

Download Search for Supersymmetry in the All-hadronic Final State Using Top Quark Tagging in Pp Collisions at Sqrt(s) Book in PDF, Epub and Kindle

A search is presented for supersymmetry in all-hadronic events with missing transverse momentum based on tagging of top quarks. The data sample corresponds to an integrated luminosity of 2.3 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC. Search regions are defined using the properties of reconstructed jets, the presence of bottom and top quark candidates, and an imbalance in transverse momentum. With no statistically significant excess of events observed beyond the expected contributions from the standard model, we set exclusion limits at 95% confidence level on the masses of new particles in the context of simplified models of direct and gluino-mediated top squark production. For direct top squark production with decays to a top quark and a neutralino, top squark masses up to 740 GeV and neutralino masses up to 240 GeV are excluded. Gluino masses up to 1550 GeV and neutralino masses up to 900 GeV are excluded for models of gluino pair production where each gluino decays to a top-antitop quark pair and a neutralino.

Searches for Supersymmetry Using the M$_{T2}$ Variable in Hadronic Events Produced in Pp Collisions at 8 TeV.

Searches for Supersymmetry Using the M$_{T2}$ Variable in Hadronic Events Produced in Pp Collisions at 8 TeV.
Author:
Publisher:
Total Pages: 51
Release: 2015
Genre:
ISBN:

Download Searches for Supersymmetry Using the M$_{T2}$ Variable in Hadronic Events Produced in Pp Collisions at 8 TeV. Book in PDF, Epub and Kindle

Searches for supersymmetry (SUSY) are performed using a sample of hadronic events produced in 8 TeV pp collisions at the CERN LHC. The searches are based on the M$_{T2}$ variable, which is a measure of the transverse momentum imbalance in an event. The data were collected with the CMS detector and correspond to an integrated luminosity of 19.5 fb1. Two related searches are performed. The first is an inclusive search based on signal regions defined by the value of the M$_{T2}$ variable, the hadronic energy in the event, the jet multiplicity, and the number of jets identified as originating from bottom quarks. The second is a search for a mass peak corresponding to a Higgs boson decaying to a bottom quark-antiquark pair, where the Higgs boson is produced as a decay product of a SUSY particle. For both searches, the principal backgrounds are evaluated with data control samples. No significant excess over the expected number of background events is observed, and exclusion limits on various SUSY models are derived.

Searches for Supersymmetry Using the MT2 Variable in Hadronic Events Produced in Pp Collisions at 8 TeV.

Searches for Supersymmetry Using the MT2 Variable in Hadronic Events Produced in Pp Collisions at 8 TeV.
Author:
Publisher:
Total Pages: 52
Release: 2015
Genre:
ISBN:

Download Searches for Supersymmetry Using the MT2 Variable in Hadronic Events Produced in Pp Collisions at 8 TeV. Book in PDF, Epub and Kindle

Searches for supersymmetry (SUSY) are performed using a sample of hadronic events produced in 8 TeV pp collisions at the CERN LHC. The searches are based on the MT2 variable, which is a measure of the transverse momentum imbalance in an event. The data were collected with the CMS detector and correspond to an integrated luminosity of 19.5 fb−1. Two related searches are performed. The first is an inclusive search based on signal regions defined by the value of the MT2 variable, the hadronic energy in the event, the jet multiplicity, and the number of jets identified as originating from bottom quarks. The second is a search for a mass peak corresponding to a Higgs boson decaying to a bottom quark-antiquark pair, where the Higgs boson is produced as a decay product of a SUSY particle. For both searches, the principal backgrounds are evaluated with data control samples. No significant excess over the expected number of background events is observed, and exclusion limits on various SUSY models are derived.

Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like?

Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like?
Author: Roman Pasechnik
Publisher: Frontiers Media SA
Total Pages: 180
Release: 2020-09-03
Genre: Science
ISBN: 2889639908

Download Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like? Book in PDF, Epub and Kindle

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 Supersymmetry in Pp Collisions at $\sqrt{s}$

Search for Supersymmetry in Pp Collisions at $\sqrt{s}$
Author:
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN:

Download Search for Supersymmetry in Pp Collisions at $\sqrt{s}$ Book in PDF, Epub and Kindle

A search for supersymmetry in hadronic final states with highly boosted W bosons and b jets is presented, focusing on compressed scenarios. The search is performed using proton-proton collision data at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.7 fb$^{-1}$. Events containing candidates for hadronic decays of boosted W bosons are identified using jet substructure techniques, and are analyzed using the razor variables $M_\mathrm{R}$ and $R^2$, which characterize a possible signal as a peak on a smoothly falling background. The observed event yields in the signal regions are found to be consistent with the expected contributions from standard model processes, which are predicted using control samples in the data. The results are interpreted in terms of gluino pair production followed by their exclusive decay into top squarks and top quarks. The analysis excludes gluino masses up to 1.1 TeV for light top squarks decaying solely to a charm quark and a neutralino, and up to 700 GeV for heavier top squarks decaying solely to a top quark and a neutralino.