Download or read book Search for Exotic Higgs Boson Decays to Merged Diphotons written by Michael Andrews and published by Springer Nature. This book was released on 2023-03-02 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the first application at CMS of deep learning algorithms trained directly on low-level, “raw” detector data, or so-called end-to-end physics reconstruction. Growing interest in searches for exotic new physics in the CMS collaboration at the Large Hadron Collider at CERN has highlighted the need for a new generation of particle reconstruction algorithms. For many exotic physics searches, sensitivity is constrained not by the ability to extract information from particle-level data but by inefficiencies in the reconstruction of the particle-level quantities themselves. The technique achieves a breakthrough in the reconstruction of highly merged photon pairs that are completely unresolved in the CMS detector. This newfound ability is used to perform the first direct search for exotic Higgs boson decays to a pair of hypothetical light scalar particles H→aa, each subsequently decaying to a pair of highly merged photons a→yy, an analysis once thought impossible to perform. The book concludes with an outlook on potential new exotic searches made accessible by this new reconstruction paradigm.
Download or read book Search for Exotic Decays of a Higgs Boson Into Undetectable Particles and One Or More Photons written by and published by . This book was released on 2015 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for exotic decays of a Higgs boson into undetectable particles and one or two isolated photons in pp collisions at a center-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of up to 19.4 inverse femtobarns collected with the CMS detector at the LHC. Higgs bosons produced in gluon-gluon fusion and in association with a Z boson are investigated, using models in which the Higgs boson decays into a gravitino and a neutralino or a pair of neutralinos, followed by the decay of the neutralino to a gravitino and a photon. The selected events are consistent with the background-only hypothesis, and limits are placed on the product of cross sections and branching fractions. Assuming a standard model Higgs boson production cross section, a 95% confidence level upper limit is set on the branching fraction of a 125 GeV Higgs boson decaying into undetectable particles and one or two isolated photons as a function of the neutralino mass. For this class of models and neutralino masses from 1 to 120 GeV an upper limit in the range of 7 to 13% is obtained. Further results are given as a function of the neutralino lifetime, and also for a range of Higgs boson masses.
Download or read book A Search for Exotic Higgs Decays written by Jackson Burzynski and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 long-lived particles (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.
Download or read book Search for Displaced Photons from Exotic Decays of the Higgs Boson with the ATLAS Detector written by Devin Mahon and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Agreement with background is observed with no significant excesses for any signal models considered. Limits at the 95% confidence level are placed on the branching ratio of the Higgs boson to two neutralinos in the context of the various signal models.
Download or read book Search for Top Squark and Higgsino Production Using Diphoton Higgs Boson Decays written by and published by . This book was released on 2013 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Exotic Decays of the Higgs Boson to a Pair of New Light Bosons in the Final States with Four Bottom Quarks written by Seyyed Mohammad Amin Ghiasi Shirazi and published by . This book was released on 2019 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we present a search for non-standard decay of the Standard Model-like Higgs boson to a pair of pseudoscalar lighter bosons H →aa with 12 Geva/sub
Download or read book A Novel Search for Exotic Decays of the Higgs Boson with the ATLAS Detector and Enhancing the Physics Potential of the Large Hadron Collider and Atom Interferometers with New Techniques written by Murtaza Safdari and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental physics research aims to understand the theory of particle interactions, the Standard Model (SM) of particle physics being the current best theory of the electroweak and strong forces. Modern efforts seeks to explain phenomenon like the matter antimatter asymmetry of the universe and the nature of dark matter using various experimental modalities such as terrestrial particle colliders like the Large Hadron Collider (LHC). The ATLAS detector on the LHC is conducting a diverse physics program of precision SM measurements and searches for Physics beyond the SM using deeply inelastic scattering products to study fundamental physics. The original research presented here uses proton collision data from the ATLAS detector to search for an exotic decay mode of the Higgs boson coupling to a new light scalar field. Additionally, two research projects are presented to improve the performance of the ATLAS detector. The first introduces a novel algorithm to improve the efficiency of locating interesting physics within saved events. The second improves the jet calibration procedure by enabling the use of gradient based regression with a novel objective function along with a unified neural network based framework. Additionally, a network of quantum sensors are in development to enhance the physics reach of modern detectors and expand the set of models of new physics that can be experimentally probed. One such technology is atomic gradiometer interferometric sensors, like the MAGIS-100 experiment, that utilize matter waves to search for ultralight bosonic dark matter. The research and development of a novel light field imaging device is presented here for the MAGIS-100 experiment, as part of a burgeoning collaboration between the high energy physics (HEP) and the atomic, molecular, and optical (AMO) physics communities.
Download or read book Exotic Decays of the 125 GeV Higgs Boson written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider (LHC). The explicit search for exotic Higgs decays presents a largely untapped discovery opportunity for the LHC collaborations, as such decays may be easily missed by other searches. We emphasize that the Higgs is uniquely sensitive to the potential existence of new weakly coupled particles and provide a unified discussion of a large class of both simplified and complete models that give rise to characteristic patterns of exotic Higgs decays. We assess the status of exotic Higgs decays after LHC run I. In many cases we are able to set new nontrivial constraints by reinterpreting existing experimental analyses. We point out that improvements are possible with dedicated analyses and perform some preliminary collider studies. As a result, we prioritize the analyses according to their theoretical motivation and their experimental feasibility.
Download or read book Search for a Fermiophobic Higgs Boson Decaying Into Diphotons in P P bar Collisions at Sqrt s written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for a narrow diphoton mass resonance is presented based on data from 3.0 fb−1 of integrated luminosity from p{bar p} collisions at √s = 1.96 TeV collected by the CDF experiment. No evidence of a resonance in the diphoton mass spectrum is observed, and upper limits are set on the cross section times branching fraction of the resonant state as a function of Higgs boson mass. The resulting limits exclude Higgs bosons with masses below 106 GeV/c2 at a 95% Bayesian credibility level (C.L.) for one fermiophobic benchmark model.
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 Supersymmetric Exotic Decays of the 125 GeV Higgs Boson written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We reveal a set of novel decay topologies for the 125 GeV Higgs boson in supersymmetry which are initiated by its decay into a pair of neutralinos, and discuss their collider search strategies. This category of exotic Higgs decays are characterized by the collider signature: visible objects + $\mbox{${\not\! E}_{\rm T}$}$, with $\mbox{${\not\! E}_{\rm T}$}$ dominantly arising from escaping dark matter particles. Their benchmark arises naturally in the Peccei-Quinn symmetry limit of the MSSM singlet-extensions, which is typified by the co-existence of three light particles: singlet-like scalar $h_1$ and pseudoscalar $a_1$, and singlino-like neutralino $\chi_1$, all with masses of $\lesssim 10$ GeV, and the generically suppression of the exotic decays of the 125 GeV Higgs boson $h_2\to h_1 h_1$, $a_1a_1$ and $\chi_1\chi_1$, however. As an illustration, we study the decay topology: $h_2 \to \chi_1 \chi_2$, where the bino-like $\chi_2$ decays to $h_1 \chi_1$ or $a_1 \chi_1$, and $h_1/a_1 \to f\bar f$, with $f\bar f = \mu^+\mu^-$, $b\bar b$. In the di-muon case ($m_{h_1/a_1} \sim 1$ GeV), a statistical sensitivity of $\frac{S}{\sqrt{B}}> 6 \sigma$ can be achieved easily at the 8 TeV LHC, assuming $\frac{\sigma(pp \rightarrow W h_2)}{\sigma(pp \rightarrow W h_{\rm SM})} {\rm Br}(h_2 \to \mu^+\mu^- \chi_1 \chi_1)=0.1$. In the $b\bar b$ case ($m_{h_1/a_1} \sim 45$ GeV), 600 fb$^{-1}$ data at the 14 TeV LHC can lead to a statistical sensitivity of $\frac{S}{\sqrt{B}}> 5 \sigma$, assuming $\frac{\sigma(pp \rightarrow Z h_2)}{\sigma(pp \rightarrow Z h_{\rm SM})} {\rm Br}(h_2 \to b\bar b \chi_1 \chi_1)=0.5$. These exotic decays open a new avenue for exploring new physics couplings with the 125 GeV Higgs boson at colliders.
Download or read book Search for a Higgs Boson in Diphoton Final States with the D0 Detector in 9 6 Fb 1 of p bar p Collisions at sqrt s written by and published by . This book was released on 2013 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exotic Decays of the 125 GeV Higgs Boson at Future e e Lepton Colliders written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Discovery of unexpected properties of the Higgs boson offers an intriguing opportunity of shedding light on some of the most profound puzzles in particle physics. The Beyond Standard Model (BSM) decays of the Higgs boson could reveal new physics in a direct manner. Future electron-positron lepton colliders operating as Higgs factories, including CEPC, FCC-ee and ILC, with the advantages of a clean collider environment and large statistics, could greatly enhance the sensitivity in searching for these BSM decays. In this work, we perform a general study of Higgs exotic decays at future $e^+e^-$ lepton colliders, focusing on the Higgs decays with hadronic final states and/or missing energy, which are very challenging for the High-Luminosity program of the Large Hadron Collider (HL-LHC). We show that with simple selection cuts, $O(10^{-3}\sim10^{-5})$ limits on the Higgs exotic decay branching fractions can be achieved using the leptonic decaying spectator $Z$ boson in the associated production mode $e^+e^-\rightarrow Z H$. We further discuss the interplay between the detector performance and Higgs exotic decay, and other possibilities of exotic decays. Our work is a first step in a comprehensive study of Higgs exotic decays at future lepton colliders, which is a key ingredient of Higgs physics that deserves further investigation.
Download or read book Search for Exotic Decays of the Higgs Boson Into B overline and Missing Transverse Momentum in Pp Collisions at square Root s written by [Study Group] ATLAS Collaboration CERN and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for an Exotic Decay of the Higgs Boson to a Pair of Light Pseudoscalars in the Final State of Two Muons and Two tau Leptons in Proton proton Collisions at s written by 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 Seeing the Light Higgs written by Khilesh Pradip Mistry and published by . This book was released on 2019 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents two results involving Standard Model Higgs bosons decaying to at least one photon. These analyses are performed using 79.8/fb-1 of proton-proton collisions collected at √s=13 TeV with the ATLAS detector at the Large Hadron Collider.
Download or read book Search and Discovery with the Resonant diphoton Final State at ATLAS written by Andrew Straiton Hard and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Standard Model Higgs boson was conducted with the ATLAS Experiment at the LHC using the two-photon decay channel. Datasets with integrated luminosities of 4.8 inverse femtobarns and 5.9 inverse femtobarns were collected in 2011 and 2012 for proton-proton collisions with center-of-mass energies of 7 TeV and 8 TeV, respectively. A statistically significant excess of events above the background-only expectation in the [diphoton] decay channel of 4.5 standard deviations was observed. Combined with excesses in the WW and ZZ decays, this observation led to the discovery of a Higgs boson with a significance of 5.9 standard deviations at a mass of 126.0 +/- 0.4 (stat) +/- 0.4 (sys) GeV. Searches for diphoton resonances during 2015 and 2016 with LHC data were motivated by extensions to the Standard Model that predict additional scalar particles. Data were analyzed from 13 TeV proton-proton collisions, corresponding to an integrated luminosity of 15.4 inverse femtobarns, and no significant deviations from the Standard Model hypothesis were observed. 95% CL limits on the production cross-section times branching ratio to [diphotons] were calculated for scalar models with masses between 200 GeV and 2.4 TeV and widths ranging from 4 MeV to 10% of the scalar mass.
