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.

RECENT RESULTS FROM ATLAS AND CMS ON HIGGS, SUPERSYMMETRY AND PHYSICS BEYOND THE STANDARD MODEL SEARCHES

2013 ◽  
Vol 28 (16) ◽  
pp. 1330026
Author(s):  
STEVE NAHN ◽  
DMITRI TSYBYCHEV
Keyword(s):  
Standard Model ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Electroweak Symmetry Breaking ◽  
Beyond The Standard Model ◽  
Electroweak Symmetry ◽  
Center Of Mass Energy ◽  
Physics Program ◽  
The Standard Model ◽  
Lhc Physics

The large hadron collider (LHC) physics program is finally on the way to help uncover the mechanism responsible for electroweak symmetry breaking, with each of experiments collecting up to 5 fb-1 of data at center-of-mass energy of 7 TeV. In this review, we summarize searches for physics beyond the Standard Model at ATLAS and CMS experiments at LHC.

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.

BEYOND THE STANDARD MODEL

2007 ◽  
Vol 22 (30) ◽  
pp. 5502-5512
Author(s):  
D. I. KAZAKOV
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Symmetry Breaking ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Beyond The Standard Model ◽  
Electroweak Symmetry ◽  
The Standard Model ◽  
Recent Developments

Review of recent developments in attempts to go beyond the Standard Model is given. We concentrate on three main unresolved problems: mechanism of electroweak symmetry breaking, expected new physics at the TeV scale (mainly SUSY) and the origin of the Dark matter.

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 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 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.

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