Download or read book Search for Associated Production of Dark Matter with a Higgs Boson Decaying to Bb Or at s written by CMS Collaboration and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Associated Production of Dark Matter with a Higgs Boson Decaying to b bar b Or gamma gamma at sqrt s written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for dark matter is performed using events with large missing transverse momentum and a Higgs boson decaying either to a pair of bottom quarks or to a pair of photons. The data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 2.3 inverse-femtobarns. Results are interpreted in the context of a Z'-two-Higgs-doublet model, where a high-mass resonance Z' decays into a pseudoscalar boson A and a CP-even scalar Higgs boson, and the A decays to a pair of dark matter particles. No significant excesses are observed over the background prediction. Combining results from the two decay channels yields exclusion limits in the signal cross section in the m[Z']-m[A] phase space. The observed data exclude, for Z' coupling strength g[Z'] = 0.8 and m[A] = 300 GeV for example, the Z' mass range of 600 to 1860 GeV. This is the first result on a search for dark matter produced in association with a Higgs boson that includes constraints on h to gamma-gamma obtained at sqrt(s) = 13 TeV.
Download or read book Search for Production of Dark Matter in Association with a Higgs Boson Decaying to Bb with the ATLAS Detector written by Matthew Baca and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using 3.2 fb^-1 of sqrt(s) =13TeV proton-proton data collected in 2015 with the ATLAS detector at the Large Hadron Collider, new limits were imposed on the associated production of Dark Matter with a 125GeV Higgs boson which decays into a pair of b-quarks. The final state of the signal is a pair of b-quark jets and large Missing Transverse Momentum attributed to the DM escaping the detector. The dominant backgrounds were simulated. These were subject to selection requirements to increase signal to background ratio. Three regions were designated based on the number of leptons in the event. 0 lepton events made up the signal region. Events with 1 and 2 leptons were control regions. Similar selection requirements were applied to the control regions as in the signal region, in order to examine a similar phase space. A blinding region was established in the 0 lepton region over the mbb distribution to mask where a reconstructed 125GeV Higgs boson would appear. The control regions and the side bands in the signal region were then fit to the mbb data distribution. Unblinding of the signal region did not result in the discovery of the decay channel, but allowed limits to be imposed.
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study reports on a search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks, using data from 20.3 fb–1 of pp collisions at a center-of-mass energy of 8 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum bb¯ system with either a pair of small-radius jets, or a single large-radius jet with substructure. The observed data are found to be consistent with the expected Standard Model backgrounds. Model-independent upper limits are placed on the visible cross sections for events with a Higgs boson decaying into bb¯ and large missing transverse momentum with thresholds ranging from 150 to 400 GeV. Results are interpreted using a simplified model with a Z' gauge boson decaying into different Higgs bosons predicted in a two-Higgs-doublet model, of which the heavy pseudoscalar Higgs decays into a pair of dark matter particles. Exclusion limits are also presented for the mass scales of various effective field theory operators that describe the interaction between dark matter particles and the Higgs boson.
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks at ATLAS written by Yangyang Cheng and published by Springer. This book was released on 2016-09-29 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports on the search for dark matter in data taken with the ATLAS detector at CERN’s Large Hadron Collider (LHC). The identification of dark matter and the determination of its properties are among the highest priorities in elementary particle physics and cosmology. The most likely candidate, a weakly interacting massive particle, could be produced in the high energy proton-proton collisions at the LHC. The analysis presented here is unique in looking for dark matter produced together with a Higgs boson that decays into its dominant decay mode, a pair of b quarks. If dark matter were seen in this mode, we would learn directly about the production mechanism because of the presence of the Higgs boson. This thesis develops the search technique and presents the most stringent production limit to date.
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to B b Using 36 Fb 1 of Pp Collisions at s written by Daniel Isaac Narrias Villar and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to a Pair of Bottom Quarks in Proton proton Collisions at sqrt s written by Albert M. Sirunyan and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Particle Physics Reference Library written by Herwig Schopper and published by Springer Nature. This book was released on 2020 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks in math Display written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Dark Matter in Events with Missing Transverse Momentum and a Higgs Boson Decaying to Two Photons in Pp Collisions at S u221A written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a search for new phenomena in events with large missing transverse momentum and a Higgs boson decaying to two photons are reported. Data from proton-proton collisions at a center-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb-1 have been collected with the ATLAS detector at the LHC. The observed data are well described by the expected standard model backgrounds. Upper limits on the cross section of events with large missing transverse momentum and a Higgs boson candidate are also placed. Exclusion limits are presented for models of physics beyond the standard model featuring dark-matter candidates.
Download or read book Ratcheting Up The Search for Dark Matter written by and published by . This book was released on 2014 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last several years have included remarkable advances in two of the primary areas of fundamental particle physics: the search for dark matter and the discovery of the Higgs boson. This dissertation will highlight some contributions made on the forefront of these exciting fields. Although the circumstantial evidence supporting the dark matter hypothesis is now almost undeniably significant, indisputable direct proof is still lacking. As the direct searches for dark matter continue, we can maximize our prospects of discovery by using theoretical techniques complementary to the observational searches to rule out additional, otherwise accessible parameter space. In this dissertation, I report bounds on a wide range of dark matter theories. The models considered here cover the spectrum from the canonical case of self-conjugate dark matter with weak-scale interactions, to electrically charged dark matter, to non-annihilating, non-fermionic dark matter. These bounds are obtained from considerations of astrophysical and cosmological data, including, respectively: diffuse gamma ray photon observations; structure formation considerations, along with an explication of the novel local dark matter structure due to galactic astrophysics; and the existence of old pulsars in dark-matter-rich environments. I also consider the prospects for a model of neutrino dark matter which has been motivated by a wide set of seemingly contradictory experimental results. In addition, I include a study that provides the tools to begin solving the speculative ``inverse'' problem of extracting dark matter properties solely from hypothetical nuclear energy spectra, which we may face if dark matter is discovered with multiple direct detection experiments. In contrast to the null searches for dark matter, we have the example of the recent discovery of the Higgs boson. The Higgs boson is the first fundamental scalar particle ever observed, and precision measurements of the production and decay of the Higgs boson represent a unique entry p! oint to searches for new kinds of physics. Continuing to refine our understanding of the Higgs boson will also allow us to learn about a vast array of possible new physics. This dissertation includes work parameterizing some of the scenarios that are most likely to be discovered with future Higgs data.
Download or read book Search for Dark Matter Coupled to the Higgs Boson at the Large Hadron Collider written by Jue Chen and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents the search for Dark Matter particles associated with the Higgs Boson decaying into a b b-bar quark pair. The dark matter search result is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the ATLAS detector during Run II. The results are interpreted in the context of a simplified model (Z'-2HDM) which describes the interaction of dark matter and standard model particles via new heavy mediator particles. The new powerful Higgs tagging techniques, which exploit the jet substructure and heavy flavor information to a large extent, are developed to improve the search sensitivity of the search. The target physics signals are signature with an optimized search region and interpreted with background estimation result statistically.
Download or read book Search for Dark Matter Produced in Association with a Hypothetical Dark Higgs Boson Decaying to W W Or ZZ Boson Pairs in the Fully Hadronic Final State at s written by Fabrizio Napolitano and published by . This book was released on 2020* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Dark Matter Produced with an Energetic Jet Or a Hadronically Decaying W Or Z Boson at sqrt s written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for dark matter particles is performed using events with large missing transverse momentum, at least one energetic jet, and no leptons, in proton-proton collisions at sqrt(s) = 13 TeV collected with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 12.9 inverse-femtobarns. The search includes events with jets from the hadronic decays of a W or Z boson. The data are found to be in agreement with the predicted background contributions from standard model processes. The results are presented in terms of simplified models in which dark matter particles are produced through interactions involving a vector, axial-vector, scalar, or pseudoscalar mediator. Vector and axial-vector mediator particles with masses up to 1.95 TeV, and scalar and pseudoscalar mediator particles with masses up to 100 and 430 GeV respectively, are excluded at 95% confidence level. The results are also interpreted in terms of the invisible decays of the Higgs boson, yielding an observed (expected) 95% confidence level upper limit of 0.44 (0.56) on the corresponding branching fraction. The results of this search provide the strongest constraints on the dark matter pair production cross section through vector and axial-vector mediators at a particle collider. When compared to the direct detection experiments, the limits obtained from this search provide stronger constraints for dark matter masses less than 5, 9, and 550 GeV, assuming vector, scalar, and axial-vector mediators, respectively. The search yields stronger constraints for dark matter masses less than 200 GeV, assuming a pseudoscalar mediator, when compared to the indirect detection results from Fermi-LAT.
Download or read book Search for Dark Matter in Association with a Higgs Boson Decaying Into B quarks with the ATLAS Detector written by Andrea Matić and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for Nothing written by William Balunas and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for invisible decays of the Higgs boson using the vector boson fusion channel. This uses 36 fb-1 of proton-proton collision data at [square root] s = 13 TeV using the ATLAS detector at the Large Hadron Collider. The experimental methods for understanding the signal and background processes as well as detector effects are described in detail. The search is carried out in several regions defined by kinematic requirements on the final-state objects, and the observed event yields are used in a profile-likelihood fit in order to constrain the backgrounds. The results are interpreted using a modified frequentist method and are found to be consistent with the Standard Model expectations. An upper limit of 34% (28% expected) at 95% C.L. is placed on the invisible branching ratio of the Higgs boson. Re-interpretation of these results in terms of dark matter is also discussed, in the context of the Higgs portal and other simplified models.
Download or read book Phenomena Beyond the Standard Model What Do We Expect for New Physics to Look Like written by Roman Pasechnik and published by Frontiers Media SA. This book was released on 2020-09-03 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
