Light Higgs And Dark Photon Searches at BABAR. PDF Download

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Languages : en
Pages : 7

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Several new-physics (NP) models predict the existence of low-mass Higgs states and light dark matter candidates. Previous BABAR searches have given null results for these new states and have excluded large regions of the NP models parameter space. We report on new searches on light Higgs and light dark matter at BABAR using the 516 fb-1 of data collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory.

Author: Marco Fabbrichesi
Publisher: Springer Nature
ISBN: 3030625192
Category : Science
Languages : en
Pages : 85

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This book is about the dark photon which is a new gauge boson whose existence has been conjectured. Due to its interaction with the ordinary, visible photon, such a particle can be experimentally detected via specific signatures. In this book, the authors review the physics of the dark photon from the theoretical and experimental point of view. They discuss the difference between the massive and the massless case, highlighting how the two phenomena arise from the same vector portal between the dark and the visible sector. A review of the cosmological and astrophysical observations is provided, together with the connection to dark matter physics. Then, a perspective on current and future experimental limits on the parameters of the massless and massive dark photon is given, as well as the related bounds on milli-charged fermions. The book is intended for graduate students and young researchers who are embarking on dark photon research, and offers them a clear and up-to-date introduction to the subject.

Author: Rocky Yat Cheung So
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author:
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Category :
Languages : en
Pages : 4

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Author:
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ISBN:
Category :
Languages : en
Pages : 17

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Presented is the current progress of a search for the signature of a dark photon or new particle using the BaBar data set. We search for the processes ee− →?{sub ISR}A′, A′ → e+e− and e+e− →?{sub ISR}?,? → A′, A′ → e+e−, where?{sub ISR} is an initial state radiated photon of energy E{sub {gamma}}>= 1 GeV. Twenty-five sets of Monte Carlo, simulating e+e− collisions at an energy of 10.58 GeV, were produced with different values of the A′ mass ranging from 100 MeV to 9.5 GeV. The mass resolution is calculated based on Monte Carlo simulations. We implement ROOT's Toolkit for Multivariate Analysis (TMVA), a machine learning tool that allows us to evaluate the signal character of events based on many of discriminating variables. TMVA training is conducted with samples of Monte Carlo as signal and a small portion of Run 6 as background. The multivariate analysis produces additional cuts to separate signal and background. The signal efficiency and sensitivity are calculated. The analysis will move forward to fit the background and scan the residuals for the narrow resonance peak of a new particle.

Author: Fred Jegerlehner
Publisher: Springer Science & Business Media
ISBN: 3540726330
Category : Science
Languages : en
Pages : 433

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This book reviews the present state of knowledge of the anomalous magnetic moment a=(g-2)/2 of the muon. The muon anomalous magnetic moment is one of the most precisely measured quantities in elementary particle physics and provides one of the most stringent tests of relativistic quantum field theory as a fundamental theoretical framework. It allows for an extremely precise check of the standard model of elementary particles and of its limitations.

Author: Khilesh Pradip Mistry
Publisher:
ISBN:
Category :
Languages : en
Pages : 498

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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.

Author: Amitava Datta
Publisher: Springer Science & Business Media
ISBN: 8184892950
Category : Science
Languages : en
Pages : 260

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In an epoch when particle physics is awaiting a major step forward, the Large Hydron Collider (LHC) at CERN, Geneva will soon be operational. It will collide a beam of high energy protons with another similar beam circulation in the same 27 km tunnel but in the opposite direction, resulting in the production of many elementary particles some never created in the laboratory before. It is widely expected that the LHC will discover the Higgs boson, the particle which supposedly lends masses to all other fundamental particles. In addition, the question as to whether there is some new law of physics at such high energy is likely to be answered through this experiment. The present volume contains a collection of articles written by international experts, both theoreticians and experimentalists, from India and abroad, which aims to acquaint a non-specialist with some basic issues related to the LHC. At the same time, it is expected to be a useful, rudimentary companion of introductory exposition and technical expertise alike, and it is hoped to become unique in its kind. The fact that there is substantial Indian involvement in the entire LHC endeavour, at all levels including fabrication, physics analysis procedures as well as theoretical studies, is also amply brought out in the collection.

Author: Gianfranco Bertone
Publisher: Oxford University Press, USA
ISBN: 0199683085
Category : Science
Languages : en
Pages : 183

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The author illustrates in non-technical terms how physicists hope to identify the nature of the mysterious form of matter that goes under the name of dark matter, and that seems to permeate the Universe.

Author: Matthew Reagan Solt
Publisher:
ISBN:
Category :
Languages : en
Pages :

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A heavy photon (also called a dark photon or A') is a hypothetical vector boson that arises from a massive U(1) abelian gauge symmetry. Heavy photons kinetically mix with the Standard Model photon, thus they are a natural portal to hidden sectors that are favored in a variety of dark sector scenarios, particularly for dark matter at the sub-GeV mass scale. The Heavy Photon Search Experiment (HPS) is a fixed target experiment at Jefferson Laboratory dedicated to searching for heavy photons in the MeV - GeV mass range and kinetic mixing strength ~1e-5 - 1e-10. It does so through two distinct searches - a search for a narrow mass resonance and, for sufficiently small couplings, a search for secondary vertices beyond a large prompt QED background. In order to perform such searches, the HPS utilizes a compact, forward acceptance spectrometer that must be able to reconstruct particle masses and vertices with extreme precision. Heavy photons are electro-produced from a continuous electron beam incident on a thin tungsten foil, and HPS is able to reconstruct the momentum of the subsequent decays to e+e- pairs using a silicon vertex tracker (SVT). HPS currently has three data sets - engineering runs in 2015 and 2016 as well as a physics run with an upgraded detector in 2019 - all at different beam energies and currents. Presented in this dissertation are heavy photon physics and motivations, introduction to the HPS detector and reconstruction, detector upgrades and other physics models of interest, and the results from the displaced vertex search from the HPS 2016 Engineering Run which was taken with a 2.3 GeV, 200 nA continuous electron beam and collected a total luminosity of 10753 1/nb (equivalent to 5.4 days of continuous beam). The 2016 Engineering Run displaced vertex search was performed in the mass range 60 - 150 MeV and in the range of kinetic mixing strength ~1e-10 - 1e-8, and the new results, which have a sensitivity to canonical A' production of ~0.4 events over a region of mass/coupling parameter space, exclude A' production above 6.05 times the canonical cross-section at a mass of 80.2 MeV and kinetic mixing strength of 2.12e-9. Even though HPS had insufficient data to set meaningful limits on the canonical A' production, this analysis demonstrated that the displaced vertex method is viable, backgrounds can be reduced to acceptable levels, and larger data sets can yield real exclusions or discovery. In fact, the background required to perform a displaced A' search (0.5 background events per mass search bin) was achieved in the unblinded 10% portion of the data set by implementing a new set of cuts. This significant background reduction stands as a considerable improvement over the previous analysis and approaches the sensitivity needed to observe the first A' candidates. After unblinding the entire data set, the remaining background events were studied and a search for decays which are further downstream and miss part of the acceptance of the tracker was performed. Finally, the sensitivity to another model which leads to displaced vertices is explored and preliminary projections show that HPS will have sensitivity to new territory with this data set. This combined work on the displaced vertex search is informative for future data sets that will search for A's in the same way but include simple, yet critical, upgrades to the detector. Studies of the detector upgrades are discussed and the expected sensitivity to future data sets with these upgrades is shown.