Search For Stopped Long Lived Particles Produced In Pp Collisions At 8 Tev At Cms
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Search For Stopped Long Lived Particles Produced In Pp Collisions At 8 Tev At Cms
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Author : Marissa L. Rodenburg
language : en
Publisher:
Release Date : 2014
Search For Stopped Long Lived Particles Produced In Pp Collisions At 8 Tev At Cms written by Marissa L. Rodenburg 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.
At the Large Hadron Collider counter-rotating proton beams are collided at sqrt(s) = 8 TeV. The Compact Muon Solenoid (CMS) is used to measure the energies and charges of the resulting cascade of particles produced in these collisions. This search focuses on the observation of massive, long-lived particles, such as the gluino, that would suggest new physics beyond the Standard Model. A custom trigger is used to probe time periods during which no proton collisions occur, thereby eliminating most backgrounds to the signal. The remaining backgrounds resulting from cosmic rays, beam-related effects, and instrumental noise, are further reduced using a series of sophisticated selection cuts. Candidate events passing all selection cuts are analyzed using a counting experiment and limits are placed on the cross sections and masses of the gluino and the supersymmetric top quark.
A Search For Exotic Higgs Decays
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Author : Jackson Burzynski
language : en
Publisher: Springer Nature
Release Date : 2023-05-23
A Search For Exotic Higgs Decays written by Jackson Burzynski and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-05-23 with Science categories.
The absence of new physics at the TeV scale observed thus far at the Large Hadron Collider (LHC) motivates an increasing focus on searches for weakly-coupled new particles and exotic signatures. In particular, particles with macroscopic mean proper lifetimes, known as long-lived particles (LLPs), are of significant interest due to their ability to elude the majority of searches which rely on the assumption that Beyond Standard Model particles decay close to the primary interaction point. Many models which aim to solve various issues with the Standard Model (SM) introduce new particles with lifetimes that are either unconstrained, or even shown to prefer the macroscopic regime. These theories often point to the Higgs boson as a possible portal to new physics, with exotic Higgs decays being the primary phenomenological consequence and means of discovery. It is well motivated both from theory and experimental constraints to consider the scenario in which the particles produced in these exotic decays have macroscopic proper lifetimes and give rise to unique detector signatures. This work describes a search for exotic decays of the Higgs boson to two long-lived, neutral, spin-0 particles which subsequently decay to pairs of b quarks, giving the striking signature of displaced hadronic jets in the ATLAS inner detector. Several other ATLAS searches have probed this decay topology previously, excluding branching ratios of the Higgs boson to LLPs of more than 10% for proper lifetimes greater than 100mm. These searches relied on dedicated triggers designed to select events with LLPs decaying in the ATLAS calorimeter or muon spectrometer. The lack of an equivalent trigger for LLP decays in the ATLAS inner detector has been a limiting factor in probing LLP lifetimes less than 100mm. To circumvent the difficulty of triggering on LLP decays, the search presented in this thesis exploits the ZH associated production mode, relying on leptonic trigger signatures to select interesting events. This is the first search for Higgs boson decays into LLPs to exploit this analysis methodology and additionally makes use of several novel methods for both background rejection and background estimation. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs . Depending on the mass of the LLP, branching ratios greater than 10% are excluded for lifetimes as small as 4mm and as large as 100mm, probing an important gap in the ATLAS exotic Higgs decay programme. In comparison to the previous searches for Higgs decays to LLPs, these are among the most stringent limits placed on this scenario, and for LLPs with masses below 40 GeV these results represent the strongest existing constraints on the branching ratio of the Higgs boson to LLPs in this lifetime regime.
The Physics Associated With Neutrino Masses
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Author : Diego Aristizabal Sierra
language : en
Publisher: Frontiers Media SA
Release Date : 2020-01-13
The Physics Associated With Neutrino Masses written by Diego Aristizabal Sierra 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 2020-01-13 with 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 Decays Of Stopped Long Lived Particles Produced In Proton U2013 Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For Decays Of Stopped Long Lived Particles Produced In Proton U2013 Proton 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 2015 with categories.
A search has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton–proton collisions. Using a data set corresponding to an integrated luminosity of 18.6 fb-1 of 8 TeV proton–proton collisions, and a search interval corresponding to 281 h of trigger livetime, 10 events are observed, with a background prediction of 13.2+3.6 -2.5 events. Limits are presented at 95 % confidence level on gluino and top squark production, for over 13 orders of magnitude in the mean proper lifetime of the stopped particle. Assuming a cloud model of R-hadron interactions, a gluino with mass ≤1000 GeV and a top squark with mass ≤525 GeV are excluded, for lifetimes between 1 æs and 1000 s. Finally, these results are the most stringent constraints on stopped particles to date.
Search For Flavor Changing Neutral Current Top Quark Decays T Hq With H Bb In Pp Collisions At S 8 Tev With The Atlas Detector
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Author : Shota Tsiskaridze
language : en
Publisher: Springer
Release Date : 2017-08-02
Search For Flavor Changing Neutral Current Top Quark Decays T Hq With H Bb In Pp Collisions At S 8 Tev With The Atlas Detector written by Shota Tsiskaridze and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-08-02 with Science categories.
This PhD thesis focuses on the search for flavor-changing neutral currents in the decay of a top quark to an up-type quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb. Further, the thesis presents the combination of this search for top quark pair events with other ATLAS searches – in the course of which the most restrictive bounds to date on tqH interactions were obtained. Following on from the discovery of the Higgs boson, it is particularly important to measure the Yukawa couplings of the Standard Model fermions; these parameters may provide crucial insights to help solve the flavor puzzle and may help reveal the presence of new physics before it is directly observed in experiments.
Search For The Decays Of Stopped Exotic Long Lived Particles Produced In P P Collisions At 13 Tev At Cms
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Author : Weifeng Ji
language : en
Publisher:
Release Date : 2018
Search For The Decays Of Stopped Exotic Long Lived Particles Produced In P P Collisions At 13 Tev At Cms written by Weifeng Ji and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Large Hadron Collider (France and Switzerland) categories.
In this dissertation, I present the searches looking for decays of stopped massive long-lived exotic particles, which are pair produced in the proton-proton collisions at 13 TeV and come to rest afterwards in the CMS detector at the CERN LHC. The decays are most likely to be observed when there are no collisions. Two specific decay scenarios are studied: a long-lived particle (LLP) decaying hadronically or semi- leptonically in the calorimeter, and a LLP decaying semi-leptonically or leptonically to a pair of muons in the muon detector. The calorimeter-based search is performed using 2.7 fb-1 of 13 TeV collision run data collected in 2015 and 35.9 fb-1 of 13 TeV collision run data collected in 2016, corresponding to a total trigger livetime of 721 hours. The muon search is performed using 2.8 fb-1 of 13 TeV collision run data collected in 2015 and 36.2 fb-1 of 13 TeV collision run data collected in 2016, corresponding to a total trigger livetime of 744 hours. Search results are interpreted in a couple of simplified models. The limits on the production cross sections and masses of LLPs are calculated as a function of particle lifetimes, which vary from 100 ns to 10 days, assuming the corresponding decaying branching fractions to be 100%. The results are the most stringent ones on the stopped LLPs so far.
Astroparticle Particle Space Physics And Detectors For Physics Applications Proceedings Of The 14th Icatpp Conference
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Author : Simone Giani
language : en
Publisher: World Scientific
Release Date : 2014-06-02
Astroparticle Particle Space Physics And Detectors For Physics Applications Proceedings Of The 14th Icatpp Conference written by Simone Giani and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-06-02 with Science categories.
The exploration of the subnuclear world is done through increasingly complex experiments covering a wide range of energy and performed in a large variety of environments ranging from particle accelerators, underground detectors to satellites and the space laboratory. The achievement of these research programs calls for novel techniques, new materials and instrumentation to be used in detectors, often of large scale. Therefore, fundamental physics is at the forefront of technological advance and also leads to many applications. Among these, are the progresses from space experiments whose results allow the understanding of the cosmic environment, of the origin and evolution of the universe after the Big Bang.
A Search For Long Lived Particles That Stop In The Cms Detector And Decay To Muons
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Author :
language : en
Publisher:
Release Date : 2016
A Search For Long Lived Particles That Stop In The Cms Detector And Decay To Muons 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 long-lived particles that are produced in proton-proton collisions at the CERN LHC, come to rest in the CMS detector, and decay to muons is presented. The decays of the stopped particles could be observed during the intervals between LHC beam crossings, at times that are well separated from any proton-proton collisions. The analysis uses 19.7 1/fb of 8 TeV data collected by CMS in 2012, during a search interval of 293 hours of trigger livetime. Massive, long-lived particles do not exist in the Standard Model, and so any sign of them would be an indication of new physics. The results are interpreted with a model that predicts a long-lived particle that has a charge of twice the electron charge and that behaves like a lepton. Cross section limits are set for each long-lived particle mass as a function of lifetime, for lifetimes between 100 ns and 10 days. These are the first limits for long-lived stopped particles that decay to muons.
Nuclear Science Abstracts
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Author :
language : en
Publisher:
Release Date : 1972
Nuclear Science Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with Nuclear energy categories.
Cern Courier
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Author :
language : en
Publisher:
Release Date : 2012
Cern Courier written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Nuclear energy categories.