scholarly journals Collinear electroweak radiation in antenna parton showers

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
Ronald Kleiss ◽  
Rob Verheyen

AbstractWe present a first implementation of collinear electroweak radiation in the Vincia parton shower. Due to the chiral nature of the electroweak theory, explicit spin dependence in the shower algorithm is required. We thus use the spinor-helicity formalism to compute helicity-dependent branching kernels, taking special care to deal with the gauge relics that may appear in computation that involve longitudinal polarizations of the massive electroweak vector bosons. These kernels are used to construct a shower algorithm that includes all possible collinear final-state electroweak branchings, including those induced by the Yang–Mills triple vector boson coupling and all Higgs couplings, as well as vector boson emissions from the initial state. We incorporate a treatment of features particular to the electroweak theory, such as the effects of bosonic interference and recoiler effects, as well as a preliminary description of the overlap between electroweak branchings and resonance decays. Some qualifying results on electroweak branching spectra at high energies, as well as effects on LHC physics are presented. Possible future improvements are discussed, including treatment of soft and spin effects, as well as issues unique to the electroweak sector.

1989 ◽  
Vol 04 (05) ◽  
pp. 1065-1110 ◽  
Author(s):  
R. CASALBUONI ◽  
S. DE CURTIS ◽  
D. DOMINICI ◽  
F. FERUGLIO ◽  
R. GATTO

The possibility that both vector and axial-vector bound states could originate from a strong interacting sector of the electroweak theory is considered. A simple Lagrangian parametrization is presented where the bound states are described as gauge vector bosons of a local, nonlinearly realized, SU (2) ⊗ SU (2) symmetry. At present the model is mostly constrained from data on W and Z masses and on neutrino-nucleon deep inelastic scattering. High energy e+e− tests are suggested where visible deviations from the standard model predictions could take place. These deviations exhibit a certain pattern which allows to distinguish the model from other theoretical frameworks. We find that precise measurements of W and Z masses and asymmetries in e+e− collisions could put strong restrictions on the parameters of the model if no appreciable deviations are found from the standard model, except for a case with the vector and axial-vector bosons degenerate in mass and coupling. General differences with respect to technicolor are pointed out.


2020 ◽  
Vol 35 (32) ◽  
pp. 2030014
Author(s):  
Thea Aarrestad

This article summarizes three searches for diboson resonances in the all-hadronic final state using data collected at a center-of-mass energy of [Formula: see text] = 13 TeV with the CMS experiment at the CERN LHC. The boson decay products are contained in one large-radius jet, resulting in dijet final states which are resolved using jet substructure techniques. The analyses presented use 2.3 fb[Formula: see text], 35.9 fb[Formula: see text] and 77.3 fb[Formula: see text] of data collected between 2015 and 2017. These include the first search for diboson resonances in data collected at a 13 TeV collision energy, the introduction of a new algorithm to tag vector bosons in the context of analyzing the data collected in 2016, and the development of a novel multidimensional fit improving on the sensitivity of the previous search method with up to 30%. The results presented here are the most sensitive to date of all diboson resonance searches in the dijet final state. An emphasis on improvements in technique for vector boson tagging is made.


1986 ◽  
Vol 41 (5) ◽  
pp. 683-703
Author(s):  
H. Stumpf

Unified nonlinear spinorfield models are self-regularizing quantum field theories in which all observable (elementary and non-elementary) particles are assumed to be bound states of fermionic preon fields. Due to their large masses the preons themselves are confined and below the threshold of preon production the effective dynamics of the model is only concerned with bound state reactions. In preceding papers a functional energy representation, the statistical interpretation and the dynamical equations were derived and the effective dynamics for preonantipreon scalar boson states and three-preon fermion (and anti-fermion) states was studied in the low energy as well as in the high energy limit, leading to a functional energy representation of an effective Yukawa theory (with high energy form-factors). In this paper the effective dynamics of two-preon composite vector bosons is studied. The weak mapping of the functional energy representation of the spinorfield on to the functional energy representation for the effective vector boson dynamics (with interactions) produces a non-abelian SU (2) local gauge theory (Yang-Mills theory) for a triplet of mass-zero vector bosons in the temporal and Coulomb gauge. This special gauge is enforced by the use of the energy representation and is compatible with the nonlinear Yang-Mills dynamics (and quantization). Apart from the non-abelian Gauss-law all other field laws and constraints directly follow from the mapping procedure. The non-abelian Gauss-law is a consequence of the relativistic invariance of the effective dynamics. PACS 11.10 Field theory PACS 12.10 Unified field theories and models PACS 12.35 Composite models of particles


2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Renato Maria Prisco ◽  
Francesco Tramontano

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.


2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Wolfgang Kilian ◽  
Sichun Sun ◽  
Qi-Shu Yan ◽  
Xiaoran Zhao ◽  
Zhijie Zhao

Abstract We study the observability of new interactions which modify Higgs-pair production via vector-boson fusion processes at the LHC and at future proton-proton colliders. In an effective-Lagrangian approach, we explore in particular the effect of the operator $$ {h}^2{W}_{\mu \nu}^a{W}^{a,\mu \nu} $$ h 2 W μν a W a , μν , which describes the interaction of the Higgs boson with transverse vector-boson polarization modes. By tagging highly boosted Higgs bosons in the final state, we determine projected bounds for the coefficient of this operator at the LHC and at a future 27 TeV or 100 TeV collider. Taking into account unitarity constraints, we estimate the new-physics discovery potential of Higgs pair production in this channel.


Author(s):  
Adriana Keating ◽  
Karen Campbell ◽  
Michael Szoenyi ◽  
Colin McQuistan ◽  
David Nash ◽  
...  

Abstract. Given the increased attention on resilience-strengthening in international humanitarian and development work, there is a growing need to invest in its measurement and the overall accountability of "resilience strengthening" initiatives. We present a framework and tool for measuring community level resilience to flooding, built around the five capitals (5Cs) of the Sustainable Livelihoods Framework. At the time of writing the tool is being tested in 75 communities across 10 countries. Currently 88 potential sources of resilience are measured at the baseline (initial state) and endline (final state) approximately two years later. If a flood occurs in the community during the study period, resilience outcome measures are recorded. By comparing pre-flood characteristics to post flood outcomes, we aim to empirically verify sources of resilience, something which has never been done in this field. There is an urgent need for the continued development of theoretically anchored, empirically verified and practically applicable disaster resilience measurement frameworks and tools so that the field may: a) deepen understanding of the key components of "disaster resilience" in order to better target resilience enhancing initiatives, and b) enhance our ability to benchmark and measure disaster resilience over time, and compare how resilience changes as a result of different capacities, actions and hazards.


Author(s):  
JUN KONG ◽  
DIANXIANG XU ◽  
XIAOQIN ZENG

Poor design has been a major source of software security problems. Rigorous and designer-friendly methodologies for modeling and analyzing secure software are highly desirable. A formal method for software development, however, often suffers from a gap between the rigidity of the method and the informal nature of system requirements. To narrow this gap, this paper presents a UML-based framework for modeling and analyzing security threats (i.e. potential security attacks) rigorously and visually. We model the intended functions of a software application with UML statechart diagrams and the security threats with sequence diagrams, respectively. Statechart diagrams are automatically converted into a graph transformation system, which has a well-established theoretical foundation. Method invocations in a sequence diagram of a security threat are interpreted as a sequence of paired graph transformations. Therefore, the analysis of a security threat is conducted through simulating the state transitions from an initial state to a final state triggered by method invocations. In our approach, designers directly work with UML diagrams to visually model system behaviors and security threats while threats can still be rigorously analyzed based on graph transformation.


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