Search For A Dark Matter Candidate Produced In Association With A Single Top Quark In P Bar P Collisions At Sqrt S
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Search For A Dark Matter Candidate Produced In Association With A Single Top Quark In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2012
Search For A Dark Matter Candidate Produced In Association With A Single Top Quark In P Bar P 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 2012 with categories.
We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb−1 of Tevatron p{bar p} collisions at √s = 1.96 TeV, collected by the CDF II detector. We search for production of a dark matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process p{bar p} → t + D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0 - 150 GeV/c2.
Science Citation Index
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language : en
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Release Date : 1993
Science Citation Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Science categories.
Vols. for 1964- have guides and journal lists.
Search For The Production Of Dark Matter In Association With Top Quark Pairs In The Single Lepton Final State In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For The Production Of Dark Matter In Association With Top Quark Pairs In The Single Lepton Final State In Proton 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 is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.
Search For Single Top Quark Production In Pbar P Collisions At Sqrt S
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language : en
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Release Date : 2010
Search For Single Top Quark Production In Pbar P 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 2010 with categories.
We report a search for single top quark production with the CDF II detector using 2.1 fb−1 of integrated luminosity of p{bar p} collisions at √s = 1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W → [tau][nu] decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations ([sigma]), with a median expected sensitivity of 1.4 [sigma]. Assuming a top quark mass of 175 GeV/c2 and ascribing the excess to single top quark production, the cross section is measured to be 4.9{sub -2.2}{sup +2.5} (stat+syst) pb, consistent with measurements performed in independent datasets and with the standard model prediction.
A Search For Dark Matter In Events With One Jet And Missing Transverse Energy In P Bar P Collisions At Sqrt S
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language : en
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Release Date : 2012
A Search For Dark Matter In Events With One Jet And Missing Transverse Energy In P Bar P 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 2012 with categories.
We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron pp collisions at √s = 1.96 TeV corresponding to an integrated luminosity of 6.7 fb−1 recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction below a dark matter candidate mass of 5 GeV/c2, and on spin-dependent interactions up to masses of 200 GeV/c2.
Search For Dark Matter In Association With A Top Quark And A W Boson In Square Root S
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Author : Paul Moder
language : en
Publisher:
Release Date : 2022
Search For Dark Matter In Association With A Top Quark And A W Boson In Square Root S written by Paul Moder 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.
Abstract: The Standard Model (SM) is the only model in particle physics containing all observed elementary particles and their interactions. Over the years, its predictions were tested and observed in a number of experiments. However, there are still observations that can not be explained by the SM with one of the most prominent ones being the existence of Dark Matter (DM). While the existence of DM was first theorised through astronomical observations, extensions of the SM allow for a search of DM at the Large Hadron Collider (LHC) as well. Since DM can not be detected directly, final states analysing its existence at the LHC are always designed around high missing transverse energy. This thesis presents a search for DM with data collected by the ATLAS detector in the years 2015-2018 corresponding to an integrated luminosity of 139~\mathrm{fb}^{-1}$ at a center of mass energy of 13~\TeV. The analysis is based on an extended two Higgs doublet model (2HDM+a) where a pseudo-scalar mediator allows the production of DM in the final state. In addition to the DM, a top quark and a \Wboson-boson are produced in the final state. This thesis mainly focuses on a final state with zero leptons which results in both the \Wboson-boson and the top quark being required to decay hadronically. In addition to that, the \Wboson-boson can be expected to have a high momentum in the signal process. Therefore, a dedicated identification algorithm using large-radius jets is employed to select events with at least one hadronically decaying \Wboson-boson. This allows for a strong distinction against SM background events. In this analysis, several different signal processes are considered, since different parameters can affect the cross section and the distributions of the signal processes. These parameters include different values for the mass of the mediator $a$, the mass of the heavy Higgs boson $H$ and $\tan\beta$. Since no significant excess was found in the signal regions when comparing SM prediction to data, upper exclusion limits on the cross section of the signal processes were calculated with a 95\% confidence level (CL). These limits are presented in three different model parameter planes. One such plane presents the upper limits for different values of the mass of the mediator, $m_a$, and the mass of the heavy Higgs boson, $m_H$, while keeping $\tan\beta = 1$. The second and third plane present the upper limits for different values of the mass of the heavy Higgs boson, $m_H$, and $\tan\beta$ while the mass of the mediator $a$ stays constant at $m_a = 250~\GeV$ and $m_a = 150~\GeV$. In addition to the upper limits for signal processes with one top quark in the final state, this thesis also provides an upper exclusion limit where this signal process is combined with a process that includes two top quarks in the final state
Search For Production Of Heavy Particles Decaying To Top Quarks And Invisible Particles In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2011
Search For Production Of Heavy Particles Decaying To Top Quarks And Invisible Particles In P Bar P 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 2011 with categories.
Search For Monotop Signatures In Proton Proton Collisions At Sqrt S
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Author :
language : en
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Release Date : 2015
Search For Monotop Signatures In Proton 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.
Results are presented from a search for new decaying massive particles whose presence is inferred from an imbalance in transverse momentum and which are produced in association with a single top quark that decays into a bottom quark and two light quarks. The measurement is performed using 19.7 fb-1 of data from proton-proton collisions at a center-of-mass energy of 8 TeV, collected with the CMS detector at the CERN LHC. No deviations from the standard model predictions are observed and lower limits are set on the masses of new invisible bosons. In particular, scalar and vector particles, with masses below 330 and 650 GeV, respectively, are excluded at 95% confidence level, thereby substantially extending a previous limit published by the CDF Collaboration.
Evidence For S Channel Single Top Quark Production In P Bar P Collisions At Sqrt S
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Author :
language : en
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Release Date : 2013
Evidence For S Channel Single Top Quark Production In P Bar P 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 2013 with categories.
Search For A Heavy Particle Decaying To A Top Quark And A Light Quark In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2012
Search For A Heavy Particle Decaying To A Top Quark And A Light Quark In P Bar P 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 2012 with categories.
We present a search for a new heavy particle M produced in association with a top quark, p{bar p} → t(M → {bar t}q) or p{bar p} → {bar t}({bar M} → t{bar q}), where q stands for up quarks and down quarks. Such a particle may explain the recent anomalous measurements of top-quark forward-backward asymmetry. If the light-flavor quark (q) is reconstructed as a jet (j), this gives a {bar t}+j or t+j resonance in t{bar t}+jet events, a previously unexplored experimental signature. In a sample of events with exactly one lepton, missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb−1 collected by the CDF II detector, we find the data to be consistent with the standard model. We set cross-section upper limits on the production (p{bar p} → Mt or {bar M} {bar t}) at 95% confidence level from 0.61 pb to 0.02 pb for M masses ranging from 200 GeV/c2 to 800 GeV/c2, respectively.