Download or read book Precision Calculations in Effective Theories for Higgs Production written by Nicolas Deutschmann and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: After a general introduction, this manuscript presents two preliminary chapters, describing first the physics context and the mathematical techniques used in this thesis.We then present the work performed in this thesis. We start with extraction of the power-suppressed of the Yukawa coupling of the bottom quark in the Higgs Effective Field Theory (HEFT) by a two-loop matching calculation between the Standard Model and the HEFT. This correction was the missing piece to improve the prediction of the production cross section of a Higgs boson in association to a pair of bottom quarks.The two next chapters present different aspects of the NLO corrections to Higgs boson production through gluon fusion in the standard model effective field theory. We first present the evaluation of the virtual corrections to this process and use the known one-loop ultraviolet and infrared divergence structure to extract a two-loop counterterm that allowed us to renormalize the amplitude, which we then analytically continued to the physical regions.We then combine this result with the automatic calculation of the real emission corrections in the program Madgraph5_aMC@NLO. The results are presented for the total cross section and differential distributions and comment on the effect of radiative corrections on these predictions.

Download or read book Automating Higgs Precision Calculations written by Johannes Braathen and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model-like Higgs boson provides an excellent setting for the indirect search of New Physics, through the study of its properties. In particular its mass is now measured with an astonishing precision, of the order of 0.1%, while being predicted in some models of Beyond the Standard Model (BSM) Physics, such as supersymmetric (SUSY) models. The main purpose of this thesis is to push further the calculation of radiative corrections to Higgs boson masses in BSM models, as well as the automation of these calculations, in order to set or improve constraints on New Physics coupling to the Higgs boson. A first chapter is devoted to the computation of the leading two-loop O (alpha_s alpha_t) corrections to neutral scalar masses in SUSY models with Dirac gauginos. Then, we show to address the Goldstone Boson Catastrophe -- a case of infra-red divergences due to massless Goldstone bosons that plague the calculation of effective potentials, tadpole equations, and self-energies -- in the context of general renormalisable field theories, by adopting an on-shell renormalisation scheme for the Goldstone masses. Afterwards, we illustrate the numerical implementation of our solution to the Goldstone Boson Catastrophe in the public tool SARAH. Finally, in a last chapter, we consider the high-scale behaviour of non-supersymmetric models with extended Higgs sectors.

Download or read book Precision Higgs Physics Effective Field Theory and Dark Matter written by Brian Quinn Henning and published by . This book was released on 2015 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent discovery of the Higgs boson calls for detailed studies of its properties. As precision measurements are indirect probes of new physics, the appropriate theoretical framework is effective field theory. In the first part of this thesis, we present a practical three-step procedure of using the Standard Model effective field theory (SM EFT) to connect ultraviolet (UV) models of new physics with weak scale precision observables. With this procedure, one can interpret precision measurements as constraints on the UV model concerned. We give a detailed explanation for calculating the effective action up to one-loop order in a manifestly gauge covariant fashion. The covariant derivative expansion dramatically simplifies the process of matching a UV model with the SM EFT, and also makes available a universal formalism that is easy to use for a variety of UV models. A few general aspects of renormalization group running effects and choosing operator bases are discussed. Finally, we provide mapping results between the bosonic sector of the SM EFT and a complete set of precision electroweak and Higgs observables to which present and near future experiments are sensitive. With a detailed understanding of how to use the SM EFT, we then turn to applications and study in detail two well-motivated test cases. The first is singlet scalar field that enables the first-order electroweak phase transition for baryogenesis; the second example is due to scalar tops in the MSSM. We find both Higgs and electroweak measurements are sensitive probes of these cases. The second part of this thesis centers around dark matter, and consists of two studies. In the first, we examine the effects of relic dark matter annihilations on big bang nucleosynthesis (BBN). The magnitude of these effects scale simply with the dark matter mass and annihilation cross-section, which we derive. Estimates based on these scaling behaviors indicate that BBN severely constrains hadronic and radiative dark matter annihilation channels in the previously unconsidered dark matter mass region MeV

Download or read book The Beauty and the Boost A Higgs Boson Tale written by Brian Moser and published by Springer Nature. This book was released on 2023-09-19 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precision measurements of the Higgs boson’s properties are a powerful tool to look for deviations from the predictions of the Standard Model (SM) of particle physics. The 139/fb of proton-proton collision data which have been collected by the ATLAS experiment during Run 2 of the LHC, offer an opportunity to investigate rare Higgs-boson topologies, which are particularly sensitive to new physics scenarios but experimentally difficult to access. Several such measurements, which target Higgs-boson decays to heavy-flavour quarks, as well as their combinations are presented in this thesis. A novel analysis that measures Higgs-boson production in association with a heavy vector boson V (VH, with V=W,Z) at high energies is presented. Dedicated Higgs-boson reconstruction techniques are applied to reconstruct the highly Lorentz-boosted Higgs-boson decays into pairs of bottom quarks. The measurement is subsequently combined with a VH cross-section measurement at low and intermediate pT(V) to provide a differential cross-section measurement in kinematic fiducial volumes over the largest possible pT(V) range. All cross-section measurements agree with the SM predictions within relative uncertainties that range from 30% to 300%. The results are furthermore interpreted as limits on the parameters of a SM effective field theory. Finally, a combination of measurements of Higgs decays to heavy-flavour quarks is used to experimentally determine that the Higgs-boson coupling to charm quarks is weaker than to bottom quarks, as predicted by the SM. The target audience for the thesis are physicists and physics students, in particular those with a background in high energy physics.

Download or read book Precision Calculations for Higgs Boson Physics at the LHC written by Florian Herren and published by . This book was released on 2020* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Higgs Physics in the Standard Model Effective Field Theory written by Jonathan Michael Cullen and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NLO Corrections and Parton Shower Effects on Electroweak Higgs Production in Association with Two Jets written by Johannes Scheller and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: While every particle predicted by the Standard Model of particle physics has been observed since the Higgs boson was finally discovered in 2012, researchers in the field continue to test the predictions by this very successful theory with enormous precision. Their hope is to be able to determine whether the Standard Model is actually the fundamental theory of the elementary particles, or whether it is part of a more comprehensive theory. Since its discovery, the properties of the Higgs boson and its various production channels have drawn special attention in the scientific community. This thesis focusses on one of these production modes, namely the electroweak production of a Higgs boson in association with two hard jets. This process is known for its high signal-to-background ratio and is expected to be particularly sensitive to the effects of new physics beyond the Standard Model. We present an implementation of this process in the publicly available framework of the POWHEG BOX RES. This implementation includes corrections at the next-to-leading order of both the strong as well as the electroweak coupling and can be matched to a so-called parton shower, therefore allowing for the calculation of exclusive distributions that can be compared to experimental results. Regarding the sub-process of vector boson fusion (VBF), we present the first calculation that allows for the matching of a parton shower with a precision calculation at the next-to leading order of the electroweak coupling. Furthermore, we do not rely on the widely used VBF approximation, which neglects contributions corresponding to the sub-process of Higgsstrahlung. We are thus able to perform precision calculations in a significantly larger part of the phase space than previous implementations in the POWHEG framework that were limited to the VBF approximation. Using our new implementation, one can calculate arbitrary kinematic distributions of the final state particles. In this thesis, this is demonstrated by a phenomenological study featuring selected important distributions. We thereby not only confirm the ability of our code to reproduce existing results at the next-to-leading order of the strong coupling, but we are also able to show the importance of corrections at next-to-leading order of the electroweak coupling. In contrast, the influence of a QED shower turns out to have only a mild influence.

Download or read book Higgs Properties at the LHC written by Jason Tsz Shing Yue and published by Springer. This book was released on 2017-08-29 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies the properties of the Higgs particle, discovered at the Large Hadron Collider (LHC) in 2012, in order to elucidate its role in electroweak symmetry breaking and cosmological phase transition in the early universe. It shows that a generic spin-2 Higgs impostor is excluded by the precision measurements of electroweak observables and perturbative unitarity considerations. It obtains LHC constraints on anomalous CP-violating Higgs-Top Yukawa couplings and examines the prospects of their measurement in future experiments. Lastly, it discusses in detail the electroweak phase transition and generation of cosmological matter–antimatter asymmetry in the universe with anomalous Higgs couplings.

Download or read book Physics of the Large and the Small written by Csaba Cs ki and published by World Scientific. This book was released on 2011 with total page 851 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents a set of pedagogical lectures that introduce particle physics beyond the standard model and particle cosmology to advanced graduate students.

Download or read book Advances in Precision Calculations of Higgs Boson and Single Top Quark Production at the Large Hadron Collider written by Jérémie Juvin-Quarroz and published by . This book was released on 2023* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Higgs Production in Association with a Top antitop Pair in the Standard Model Effective Field Theory at NLO in QCD written by and published by . This book was released on 2016 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the results of the computation of the next-to-leading order QCD corrections to the production cross section of a Higgs boson in association with a top-antitop pair at the LHC, including the three relevant dimension-six operators (Ot[phi], O[phi]G, OtG) of the standard model effective field theory. These operators also contribute to the production of Higgs bosons in loop-induced processes at the LHC, such as inclusive Higgs, Hj and HH production, and modify the Higgs decay branching ratios for which we also provide predictions. We perform a detailed study of the cross sections and their uncertainties at the total as well as differential level and of the structure of the effective field theory at NLO including renormalisation group effects. Finally, we show how the combination of information coming from measurements of these production processes will allow to constrain the three operators at the current and future LHC runs. Finally, our results lead to a significant improvement of the accuracy and precision of the deviations expected from higher-dimensional operators in the SM in both the top-quark and the Higgs-boson sectors and provide a necessary ingredient for performing a global EFT fit to the LHC data at NLO accuracy.

Download or read book Physics at the Large Hadron Collider written by Amitava Datta and published by Springer Science & Business Media. This book was released on 2010-05-30 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Higgs Phenomenology in Warped Extra Dimensions written by Nima Pourtolami and published by . This book was released on 2015 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a study on phenomenology of beyond the Standard Model in the context of warped extra-dimensional (Randall-Sundrum) models. These models, through introducing a large extra space dimension along which the standard model fields can propagate, can address the hierarchy between the Plank and weak scales, provided that the geometry is suitably curved along the fifth dimension and the extra dimension is stabilized. The space-time background that is considered in this thesis is mainly in a more general form which is modified from the usual AdS5. This modification can alleviate considerably the bounds coming from precision electroweak tests and flavor physics. Of course, the usual AdS5 geometry is a special case and can be reproduced by taking the correct limits. In this thesis, we mainly consider the case where the extra dimension is bounded by two stabilized hard walls (branes) at the TeV (IR brane) and Plank (UV brane) scales. Also our principal consideration will be the case when all the standard model fields propagate in the bulk, although we comment on the case where only the Higgs is localized on the TeV brane. Within this context, after a broad review of the main concepts, we first address the phenomenology of a bulk scalar Higgs boson, and calculate its production cross section at the LHC as well as its tree-level effects on mediating flavor changing neutral currents. We perform the calculations based on two different approaches. First, we compute our predictions analytically by considering all the degrees of freedom emerging from the dimensional reduction (the infinite tower of Kaluza-Klein modes (KK)). In the second approach, we perform our calculations numerically by considering only the effects caused by the first few KK modes, present in the 4-dimensional effective theory. In the case of a Higgs leaking far from the brane, both approaches give the same predictions as the effects of the heavier KK modes decouple. However, as the Higgs boson is pushed towards the TeV brane, the two approaches seem to be equivalent only when one includes heavier and heavier degrees of freedom (which do not seem to decouple). To reconcile these results it is necessary to introduce a type of higher derivative operator which essentially encodes the effects of integrating out the heavy KK modes and dresses the brane Higgs so that it looks just like a bulk Higgs. Secondly we calculate the production rate of the Higgs boson at the LHC in the context of general 5D warped scenarios, and show that it is generically consistent with the current experimental results from the LHC for Kaluza-Klein (KK) masses as low as 2 TeV, unlike in pure AdS5 scenarios, where for the same masses, the Higgs production typically receives corrections too large to be consistent with LHC data. Thus the new pressure on warped models arising from LHC Higgs data is also alleviated in modified AdS5 warped scenarios. And finally we show that in these backgrounds, high energy flavor symmetries are inherent. When these high energy symmetries are broken at lower energies, they produce the Standard Model (SM) structure including the neutrinos. This feature is completely general and depends neither on the details of the background metric, as long as it produces the required hierarchy, nor on the exact form of the symmetry, as long as it produces the required PMNS matrix. The reason for this phenomena is inherent in the structure of the exponential hierarchy factors of warped extra-dimension scenarios with bulk matter fields. While these factors produce the hierarchy of masses in quarks and charged lepton sectors, they flatten in to a plateau at larger c-parameters to accommodate the neutrinos. In the case of the quark and charged lepton sectors, these exponential hierarchy factors ?wash off? the structure of the order one five dimensional Yukawa couplings, and naturally produce the hierarchical masses and the CKM matrix, while for the neutrinos sector, while for the neutrinos, the structure of the high energy symmetries are preserved to attain the SM.

Download or read book Physics at the LHC written by Tania Robens 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 Cosmology in Gauge Field Theory and String Theory written by D. Bailin and published by CRC Press. This book was released on 2021-09-29 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmology in Gauge Field Theory and String Theory focuses on the cosmological implications of the gauge theories of particle physics and of string theory. The book first examines the universe's series of phase transitions in which the successive gauge symmetries of the higher-temperature phase were spontaneously broken after the big bang, discussing relics of these phase transitions, more generic relics (baryons, neutrinos, axions), and supersymmetric particles (neutralinos and gravitinos). The author next studies supersymmetric theory, supergravity theory, and the constraints on the underlying field theory of the universe's inflationary era. The book concludes with a discussion of black hole solutions of the supergravity theory that approximates string theory at low energies and the insight that string theory affords into the microscopic origin of the Bekenstein-Hawking entropy. Cosmology in Gauge Field Theory and String Theory provides a modern introduction to these important problems from a particle physicist's perspective. It is intended as an introductory textbook for a first course on the subject at a graduate level.

Download or read book LHC Phenomenology written by Einan Gardi and published by Springer. This book was released on 2014-08-27 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a very broad spectrum of experimental and theoretical activity in particle physics, from the searches for the Higgs boson and physics beyond the Standard Model, to detailed studies of Quantum Chromodynamics, the B-physics sectors and the properties of hadronic matter at high energy density as realised in heavy-ion collisions. Starting with a basic introduction to the Standard Model and its most likely extensions, the opening section of the book presents an overview of the theoretical and phenomenological framework of hadron collisions and current theoretical models of frontier physics. In part II, discussion of the theory is supplemented by chapters on the detector capabilities and search strategies, as well as an overview of the main detector components, the initial calibration procedures and physics samples and early LHC results. Part III completes the volume with a description of the physics behind Monte Carlo event generators and a broad introduction to the main statistical methods used in high energy physics. LHC Phenomenology covers all of these topics at a pedagogical level, with the aim of providing young particle physicists with the basic tools required for future work on the various LHC experiments. It will also serve as a useful reference text for those working in the field.

Download or read book The Standard Theory of Particle Physics written by Luciano Maiani and published by World Scientific Publishing Company. This book was released on 2016-08-25 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a quite complete and up-to-date picture of the Standard Theory with an historical perspective, with a collection of articles written by some of the protagonists of present particle physics. The theoretical developments are described together with the most up-to-date experimental tests, including the discovery of the Higgs Boson and the measurement of its mass as well as the most precise measurements of the top mass, giving the reader a complete description of our present understanding of particle physics.