scholarly journals Polarized electroweak bosons in W+W− production at the LHC including NLO QCD effects

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Ansgar Denner ◽  
Giovanni Pelliccioli
Keyword(s):  
Cross Sections ◽  
W Boson ◽  
Z Bosons ◽  
Electroweak Symmetry Breaking ◽  
Special Focus ◽  
Electroweak Symmetry ◽  
Final State ◽  
The Standard Model ◽  
Breaking Mechanism ◽  
Resonant Part

Abstract The measurement of polarization fractions of massive gauge bosons at the LHC provides an important check of the Standard Model and in particular of the Electroweak Symmetry Breaking mechanism. Owing to the unstable character of W and Z bosons, devising a theoretical definition for polarized signals is not straightforward and always subject to some ambiguity. Focusing on W-boson pair production at the LHC in the fully leptonic channel, we propose to compute polarized cross-sections and distributions based on the gauge-invariant doubly-resonant part of the amplitude. We include NLO QCD corrections to the leading quark-induced partonic process and also consider the loop- induced gluon-initiated process contributing to the same final state. We present results for both an inclusive setup and a realistic fiducial region, with special focus on variables that are suited for the discrimination of polarized cross-sections and on quantities that can be measured experimentally.

scholarly journals NLO EW and QCD corrections to polarized ZZ production in the four-charged-lepton channel at the LHC

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Ansgar Denner ◽  
Giovanni Pelliccioli
Keyword(s):  
Cross Sections ◽  
Z Bosons ◽  
Electroweak Symmetry Breaking ◽  
Pole Approximation ◽  
Electroweak Symmetry ◽  
Matrix Elements ◽  
Model Predictions ◽  
Breaking Mechanism ◽  
First Time ◽  
Amplitude Level

Abstract Measuring the polarization of electroweak bosons at the LHC allows for important tests of the electroweak-symmetry-breaking mechanism that is realized in nature. Therefore, precise Standard Model predictions are needed for the production of polarized bosons in the presence of realistic kinematic selections. We formulate a method for the calculation of polarized cross-sections at NLO that relies on the pole approximation and the separation of polarized matrix elements at the amplitude level. In this framework, we compute NLO-accurate cross-sections for the production of two polarized Z bosons at the LHC, including for the first time NLO EW corrections and combining them with NLO QCD corrections and contributions from the gluon-induced process.

scholarly journals NNLO QCD study of polarised W+W− production at the LHC

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Rene Poncelet ◽  
Andrei Popescu
Keyword(s):  
Direct Consequence ◽  
Electroweak Symmetry Breaking ◽  
Beyond The Standard Model ◽  
Pole Approximation ◽  
Electroweak Symmetry ◽  
Double Pole ◽  
Diboson Production ◽  
The Standard Model ◽  
Breaking Mechanism ◽  
Insight Into

Abstract Longitudinal polarisation of the weak bosons is a direct consequence of Electroweak symmetry breaking mechanism providing an insight into its nature, and is instrumental in searches for physics beyond the Standard Model. We perform a polarisation study of the diboson production in the pp →$$ {\mathrm{e}}^{+}{v}_{\mathrm{e}}{\mu}^{-}{\overline{v}}_{\mu } $$ e + v e μ − v ¯ μ process at NNLO QCD in the fiducial setup inspired by experimental measurements at ATLAS. This is the first polarisation study at NNLO. We employ the double-pole approximation framework for the polarised calculation, and investigate NNLO effects arising in differential distributions.

NEW NEUTRAL GAUGE BOSONS AT HIGH ENERGY e+e− COLLIDERS

1989 ◽  
Vol 04 (17) ◽  
pp. 4551-4565 ◽  
Author(s):  
JOANNE L. HEWETT ◽  
THOMAS G. RIZZO
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Z Bosons ◽  
High Energy ◽  
Beam Polarization ◽  
Gauge Bosons ◽  
Final State ◽  
The Standard Model ◽  
Model Predictions ◽  
Coupling Parameters

We discuss and contrast search limits for and properties of new Z′ gauge bosons which can be probed at high energy e+e− colliders within the context of several E6 superstring-inspired models. In particular, we discuss the probability of distinguishing these various models from one another and determining the Z′ coupling parameters uniquely. Using the deviations from the standard model predictions for asymmetries and cross sections for various final state fermions, we set discovery limits for new Z′ bosons at [Formula: see text] and 1 TeV e+e− colliders. We find quite generally that cross section deviations provide the strongest limits on the existence of new Z′ bosons below threshold even when 100% beam polarization is available. The possibility of using Z′ pair production as a sensitive probe of the e+e−Z′ coupling is also examined.

scholarly journals Electroweak symmetry breaking in the inverse seesaw mechanism

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Sanjoy Mandal ◽  
Rahul Srivastava ◽  
José W. F. Valle
Keyword(s):  
Planck Scale ◽  
Lepton Number ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Seesaw Mechanism ◽  
Yukawa Couplings ◽  
Lepton Number Violation ◽  
Higgs Vacuum ◽  
The Standard Model ◽  
The Stability

Abstract We investigate the stability of Higgs potential in inverse seesaw models. We derive the full two-loop RGEs of the relevant parameters, such as the quartic Higgs self-coupling, taking thresholds into account. We find that for relatively large Yukawa couplings the Higgs quartic self-coupling goes negative well below the Standard Model instability scale ∼ 1010 GeV. We show, however, that the “dynamical” inverse seesaw with spontaneous lepton number violation can lead to a completely consistent and stable Higgs vacuum up to the Planck scale.

scholarly journals W-boson production in the high energy electron-photon collisions

2019 ◽  
pp. 41-50
Author(s):  
Ivan A. Shershan ◽  
Tatiana V. Shishkina
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
W Boson ◽  
High Energy ◽  
New Physics ◽  
Coupling Constants ◽  
Boson Production ◽  
The Standard Model ◽  
Electron Photon ◽  
W Boson Production

In this paper the analysis of W-boson production process in high-energy electron-photon collisions as a tool to search for deviations from the Standard Model is considered. In particular, a set of extended gauge models, including anomalous multi-boson interactions, are discussed as a promising way for «new physics» study. A numerical analysis of the total cross sections of the processes was carried out. The lowest order radiative corrections in the soft-photon approximation within the Standard Model are taken into account. Calculations beyond the Standard Model was performed, the kinematic features of the cross sections were identified. The restrictions on the anomalous triple gauge boson coupling constants were analyzed and the kinematic areas to the search for their manifestations were obtained during the experiments at the International Linear Collider. The paper shows that the search for «new physics» effects based on electron-photon collisions around the W-boson production peak is the maximal promising. It was also shown that future experiments at high luminosity linear colliders will significantly clarify the constraints on anomalous gauge coupling constants.

scholarly journals Constraining the gauge and scalar sectors of the doublet left-right symmetric model

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Véronique Bernard ◽  
Sébastien Descotes-Genon ◽  
Luiz Vale Silva
Keyword(s):  
Symmetry Breaking ◽  
Electroweak Symmetry Breaking ◽  
Symmetric Model ◽  
Electroweak Symmetry ◽  
Gauge Bosons ◽  
Spontaneous Breakdown ◽  
The Standard Model ◽  
Low Energies ◽  
Precision Observables ◽  
Electroweak Precision

Abstract We consider a left-right symmetric extension of the Standard Model where the spontaneous breakdown of the left-right symmetry is triggered by doublets. The electroweak ρ parameter is protected from large corrections in this Doublet Left-Right Model (DLRM), contrary to the triplet case. This allows in principle for more diverse patterns of symmetry breaking. We consider several constraints on the gauge and scalar sectors of DLRM: the unitarity of scattering processes involving gauge bosons with longitudinal polarisations, the radiative corrections to the muon ∆r parameter and the electroweak precision observables measured at the Z pole and at low energies. Combining these constraints within the frequentist CKMfitter approach, we see that the fit pushes the scale of left-right symmetry breaking up to a few TeV, while favouring an electroweak symmetry breaking triggered not only by the SU(2)L×SU(2)R bi-doublet, which is the case most commonly considered in the literature, but also by the SU(2)L doublet.

scholarly journals A SUPERSYMMETRIC MODEL WITH THE GAUGE SYMMETRY SU(3)1 × SU(2)1 × U(1)1 × SU(3)2 × SU(2)2 × U(1)2

2003 ◽  
Vol 18 (14) ◽  
pp. 967-975 ◽  
Author(s):  
J. G. KÖRNER ◽  
CHUN LIU
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Supersymmetry Breaking ◽  
Simple Form ◽  
Electroweak Symmetry Breaking ◽  
Supersymmetric Model ◽  
Electroweak Symmetry ◽  
Gauge Groups ◽  
The Standard Model

A supersymmetric model with two copies of the Standard Model gauge groups is constructed in the gauge mediated supersymmetry breaking scenario. The supersymmetry breaking messengers are in a simple form. The Standard Model is obtained after first step gauge symmetry breaking. In the case of one copy of the gauge interactions being strong, a scenario of electroweak symmetry breaking is discussed, and the gauginos are generally predicted to be heavier than the sfermions.

scholarly journals THE HIGGS PUZZLE: EXPERIMENT AND THEORY

2002 ◽  
Vol 17 (23) ◽  
pp. 3300-3317
Author(s):  
FABIO ZWIRNER
Keyword(s):  
Higgs Boson ◽  
High Energy ◽  
Experimental Information ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Supersymmetric Extension ◽  
Light Higgs Boson ◽  
Open Questions ◽  
The Standard Model ◽  
Spatial Dimensions

The present experimental and theoretical knowledge of the physics of electroweak symmetry breaking is reviewed. Data still favor a light Higgs boson, of a kind that can be comfortably accommodated in the Standard Model or in its Minimal Supersymmetric extension, but exhibit a non-trivial structure that leaves some open questions. The available experimental information may still be reconciled with the absence of a light Higgs boson, but the price to pay looks excessive. Recent theoretical ideas, linking the weak scale with the size of possible extra spatial dimensions, are briefly mentioned. It is stressed once more that experiments at high-energy colliders, such as the Tevatron and the LHC, are the crucial tool for eventually solving the Higgs puzzle.

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