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 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 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.

COLOR-SEXTET QUARK PRODUCTIONS AT HADRON COLLIDERS

1992 ◽  
Vol 07 (12) ◽  
pp. 2679-2693 ◽  
Author(s):  
HIDEKAZU TANAKA ◽  
ISAMU WATANABE
Keyword(s):  
Symmetry Breaking ◽  
Cross Sections ◽  
Top Quark ◽  
Production Cross ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Hadron Colliders ◽  
Dynamical Mechanism

Production cross-sections of color-sextet quarks at hadron colliders are estimated in various energies and the results are compared with cross-sections of the conventional top quark productions. Particular attentions are paid for a model recently proposed in Ref. 2 in order to explain the dynamical mechanism of the electroweak symmetry breaking. The model may be tested at SSC and LHC if the sextet quarks dominantly decay semileptonically through effective fourfermion interactions, or if the sextet quarks have long enough lifetime to reach the detectors.

scholarly journals PROBING ELECTROWEAK SYMMETRY BREAKING MECHANISM AT THE LHC: A GUIDELINE FROM POWER COUNTING ANALYSIS

1996 ◽  
Vol 11 (39n40) ◽  
pp. 3061-3074 ◽  
Author(s):  
HONG-JIAN HE ◽  
YU-PING KUANG ◽  
C.-P. YUAN
Keyword(s):  
Symmetry Breaking ◽  
Hadron Collider ◽  
Equivalence Theorem ◽  
Power Counting ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Systematic Analysis ◽  
Theoretical Criterion ◽  
Breaking Mechanism ◽  
Chiral Lagrangian

We formulate the equivalence theorem as a theoretical criterion for sensitively probing the electroweak symmetry breaking mechanism, and develop a precise power counting method for the chiral Lagrangian formulated electroweak theories. Armed with these, we perform a systematic analysis on the sensitivities of the scattering processes W±W±→W±W± and [Formula: see text] for testing all possible effective bosonic operators in the chiral Lagrangian formulated electroweak theories at the CERN Large Hadron Collider (LHC). The analysis shows that these two kinds of processes are complementary in probing the electroweak symmetry breaking sector.

scholarly journals INVESTIGATIONS OF ELECTROWEAK SYMMETRY BREAKING MECHANISM FOR HIGGS BOSON DECAYS INTO FOUR FERMIONS

2020 ◽  
pp. 8-12
Author(s):  
T.V. Obikhod ◽  
E.A. Petrenko
Keyword(s):  
Higgs Boson ◽  
Symmetry Breaking ◽  
Gluon Fusion ◽  
Higgs Doublet ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Decay Modes ◽  
Significant Difference ◽  
Vector Bosons ◽  
Breaking Mechanism

Models with extended Higgs boson sectors are of prime importance for investigating the mechanism of electroweak symmetry breaking for Higgs decays into four fermions and for Higgs-production in association with a vector bosons. In the framework of the Two-Higgs-Doublet Model using two scenarios obtained from the experimental measurements we presented next-to-leading-order results on the four-fermion decays of light CP-even Higgs boson, h → 4f. With the help of Monte Carlo program Prophecy 4f 3.0, we calculated the values Γ = ΓEW/(ΓEW + ΓSM) and Γ = ΓEW+QCD/(ΓEW+QCD + ΓSM) for Higgs boson decay channels H → νµµeνe, µµee, eeee. We didn’t find significant difference when accounting QCD corrections to EW processes in the decay modes of Higgs boson. Using computer programs Pythia 8.2 and FeynHiggs we calculated the following values: σ(V BH)BR(H → ZZ) and σ(V BF)BR(H → WW) for VBF production processes, σ(ggH)BR(H → WW) and σ(ggH)BR(H → ZZ) for gluon fusion production process at 13 and 14 TeV and found good agreement with experimental data.

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.

LARGE CROSS-SECTIONS FOR W+W− AND Z0Z0 PAIRS AND COLOR SEXTET QUARKS

1987 ◽  
Vol 02 (06) ◽  
pp. 397-408 ◽  
Author(s):  
ALAN R. WHITE
Keyword(s):  
Symmetry Breaking ◽  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Chiral Condensate ◽  
Electroweak Symmetry Breaking ◽  
Grand Unification ◽  
Electroweak Symmetry ◽  
Scaling Arguments

Dynamical electroweak symmetry breaking by a chiral condensate of color sextet quarks is expected to produce large cross-sections for W+W− and Z0Z0 pairs due to direct QCD production. Cross-section estimates based on a combination of chiral and diffractive scaling arguments are shown to be consistent with the candidate events observed at CERN. Other implications of sextet quarks for QCD dynamics and for Grand Unification are also briefly described.

scholarly journals CAN γγ → ZLZL SERVE AS A PROBE OF THE ELECTROWEAK SYMMETRY BREAKING SECTOR?

1994 ◽  
Vol 09 (08) ◽  
pp. 735-747 ◽  
Author(s):  
ROGERIO ROSENFELD
Keyword(s):  
Symmetry Breaking ◽  
Cross Section ◽  
Cross Sections ◽  
Electroweak Symmetry Breaking ◽  
Resonance Structure ◽  
Electroweak Symmetry ◽  
Vector Resonance ◽  
Scalar Resonance ◽  
Low Mass ◽  
Heavy Higgs Boson

We investigate the feasibility of distinguishing among different models of electroweak symmetry breaking by studying the process γγ → Z L Z L at photon colliders. For models with a low mass Higgs-like scalar resonance, the s-channel contribution provides a distinct resonance structure and large cross-sections. However, the absence of a resonance structure in the cross-section for the above process does not discriminate in principle between the existence of either a heavy Higgs boson or a vector resonance of a nonlinearly realized symmetry.

Sign in / Sign up

Export Citation Format

Share Document