# Polarized vector boson scattering in the fully leptonic WZ and ZZ channels at the LHC

- 15 Downloads

## Abstract

Isolating the scattering of longitudinal weak bosons at the LHC is an important tool to probe the ElectroWeak Symmetry Breaking mechanism. Separating polarizations of *W* and *Z* bosons is complicated, because of non resonant contributions and interference effects. Additional care is necessary when considering *Z* bosons, due to the γ*/Z* mixing in the coupling to charged leptons. We propose a method to define polarized signals in *ZZ* and *W*^{+}*Z* scattering at the LHC, which relies on the separation of weak boson polarizations at the amplitude level in Monte Carlo simulations. After validation in the absence of lepton cuts, we investigate how polarized distributions are affected by a realistic set of kinematic cuts (and neutrino reconstruction, when needed). The total and differential polarized cross sections computed at the amplitude level are well defined, and their sum reproduces the full results, up to non negligible but computable interference effects which should be included in experimental analyses. We show that polarized cross sections computed using the reweighting method are inaccurate, particularly at large energies. We also present two procedures which address the model independent extraction of polarized components from LHC data, using Standard Model angular distribution templates.

## Keywords

Beyond Standard Model Higgs Physics## Notes

### **Open Access**

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited

## References

- [1]CMS collaboration,
*Measurement of vector boson scattering and constraints on anomalous quartic couplings from events with four leptons and two jets in proton-proton collisions at*\( \sqrt{s} \) = 13*TeV*,*Phys. Lett.***B 774**(2017) 682 [arXiv:1708.02812] [INSPIRE]. - [2]CMS collaboration,
*Observation of electroweak production of same-sign W boson pairs in the two jet and two same-sign lepton final state in proton-proton collisions at*\( \sqrt{s} \) = 13*TeV*,*Phys. Rev. Lett.***120**(2018) 081801 [arXiv:1709.05822] [INSPIRE]. - [3]ATLAS collaboration,
*Observation of electroweak production of a same-sign W boson pair in association with two jets in pp collisions at*\( \sqrt{s} \) = 13*TeV with the ATLAS detector*, arXiv:1906.03203 [INSPIRE]. - [4]ATLAS collaboration,
*Observation of electroweak W*^{±}*Z boson pair production in association with two jets in pp collisions at*\( \sqrt{s} \) = 13*TeV with the ATLAS detector*,*Phys. Lett.***B 793**(2019) 469 [arXiv:1812.09740] [INSPIRE]. - [5]CMS collaboration,
*Measurement of electroweak WZ boson production and search for new physics in WZ + two jets events in pp collisions at*\( \sqrt{s} \) = 13*TeV*,*Phys. Lett.***B 795**(2019) 281 [arXiv:1901.04060] [INSPIRE]. - [6]CMS collaboration,
*Vector Boson Scattering prospective studies in the ZZ fully leptonic decay channel for the High-Luminosity and High-Energy LHC upgrades*, CMS-PAS-FTR-18-014 [INSPIRE]. - [7]HL-LHC and HE-LHC Working Group collaborations,
*Standard Model Physics at the HL-LHC and HE-LHC*, arXiv:1902.04070 [INSPIRE]. - [8]Z. Bern et al.,
*Left-Handed W Bosons at the LHC*,*Phys. Rev.***D 84**(2011) 034008 [arXiv:1103.5445] [INSPIRE].ADSGoogle Scholar - [9]W.J. Stirling and E. Vryonidou,
*Electroweak gauge boson polarisation at the LHC*,*JHEP***07**(2012) 124 [arXiv:1204.6427] [INSPIRE].ADSCrossRefGoogle Scholar - [10]A. Belyaev and D. Ross,
*What Does the CMS Measurement of W-polarization Tell Us about the Underlying Theory of the Coupling of W-Bosons to Matter?*,*JHEP***08**(2013) 120 [arXiv:1303.3297] [INSPIRE].ADSCrossRefGoogle Scholar - [11]J. Baglio and N. Le Duc,
*Fiducial polarization observables in hadronic WZ production: A next-to-leading order QCD+EW study*,*JHEP***04**(2019) 065 [arXiv:1810.11034] [INSPIRE]. - [12]CMS collaboration,
*Measurement of the Polarization of W Bosons with Large Transverse Momenta in W+Jets Events at the LHC*,*Phys. Rev. Lett.***107**(2011) 021802 [arXiv:1104.3829] [INSPIRE]. - [13]ATLAS collaboration,
*Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at*\( \sqrt{s} \) = 7*TeV with the ATLAS experiment*,*Eur. Phys. J.***C 72**(2012) 2001 [arXiv:1203.2165] [INSPIRE]. - [14]ATLAS collaboration,
*Measurement of the W boson polarisation in t*\( \overline{t} \)*events from pp collisions at*\( \sqrt{s} \) = 8*TeV in the lepton + jets channel with ATLAS*,*Eur. Phys. J.***C 77**(2017) 264 [*Erratum ibid.***C 79**(2019) 19] [arXiv:1612.02577] [INSPIRE]. - [15]CMS collaboration,
*Measurement of the W boson helicity fractions in the decays of top quark pairs to lepton*+*jets final states produced in pp collisions at*\( \sqrt{s} \) = 8*TeV*,*Phys. Lett.***B 762**(2016) 512 [arXiv:1605.09047] [INSPIRE]. - [16]A. Ballestrero, E. Maina and G. Pelliccioli,
*W boson polarization in vector boson scattering at the LHC*,*JHEP***03**(2018) 170 [arXiv:1710.09339] [INSPIRE].CrossRefGoogle Scholar - [17]A. Kadeer, J.G. Körner and U. Moosbrugger,
*Helicity analysis of semileptonic hyperon decays including lepton mass effects*,*Eur. Phys. J.***C 59**(2009) 27 [hep-ph/0511019] [INSPIRE]. - [18]A. Aeppli, F. Cuypers and G.J. van Oldenborgh,
*O(*Γ*) corrections to W pair production in e*^{+}*e*^{−}*and γγ collisions*,*Phys. Lett.***B 314**(1993) 413 [hep-ph/9303236] [INSPIRE]. - [19]A. Aeppli, G.J. van Oldenborgh and D. Wyler,
*Unstable particles in one loop calculations*,*Nucl. Phys.***B 428**(1994) 126 [hep-ph/9312212] [INSPIRE]. - [20]A. Denner, S. Dittmaier, M. Roth and D. Wackeroth,
*Electroweak radiative corrections to e*^{+}*e*^{−}→*W W*→ 4*fermions in double pole approximation: The RACOONWW approach*,*Nucl. Phys.***B 587**(2000) 67 [hep-ph/0006307] [INSPIRE]. - [21]M. Billóni, S. Dittmaier, B. Jäger and C. Speckner,
*Next-to-leading order electroweak corrections to pp*→*W*^{+}*W*^{−}→ 4*leptons at the LHC in double-pole approximation*,*JHEP***12**(2013) 043 [arXiv:1310.1564] [INSPIRE].ADSCrossRefGoogle Scholar - [22]B. Biedermann et al.,
*Next-to-leading-order electroweak corrections to pp*→*W*^{+}*W*^{−}→*4 leptons at the LHC*,*JHEP***06**(2016) 065 [arXiv:1605.03419] [INSPIRE]. - [23]A. Ballestrero, A. Belhouari, G. Bevilacqua, V. Kashkan and E. Maina,
*PHANTOM: A Monte Carlo event generator for six parton final states at high energy colliders*,*Comput. Phys. Commun.***180**(2009) 401 [arXiv:0801.3359] [INSPIRE].ADSCrossRefGoogle Scholar - [24]A. Ballestrero and E. Maina,
*A new method for helicity calculations*,*Phys. Lett.***B 350**(1995) 225 [hep-ph/9403244] [INSPIRE]. - [25]LHC Higgs Cross Section Working Group collaboration,
*Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector*, arXiv:1610.07922 [INSPIRE]. - [26]A. Denner, S. Dittmaier, P. Maierhöfer, M. Pellen and C. Schwan,
*QCD and electroweak corrections to WZ scattering at the LHC*,*JHEP***06**(2019) 067 [arXiv:1904.00882] [INSPIRE].ADSCrossRefGoogle Scholar - [27]B. Jäger, A. Karlberg and J. Scheller,
*Parton-shower effects in electroweak W Zjj production at the next-to-leading order of QCD*,*Eur. Phys. J.***C 79**(2019) 226 [arXiv:1812.05118] [INSPIRE].ADSCrossRefGoogle Scholar - [28]C. Bittrich,
*Study of Polarization Fractions in the Scattering of Massive Gauge Bosons W*^{±}*Z*→*W*^{±}*Z with the ATLAS Detector at the Large Hadron Collider*, MSc Thesis, Dresden, Tech. U., (2015).Google Scholar - [29]CMS collaboration,
*Angular coefficients of Z bosons produced in pp collisions at*\( \sqrt{s} \) = 8*TeV and decaying to μ*^{+}*μ*^{−}*as a function of transverse momentum and rapidity*,*Phys. Lett.***B 750**(2015) 154 [arXiv:1504.03512] [INSPIRE]. - [30]ATLAS collaboration,
*Measurement of Top Quark Polarization in Top-Antitop Events from Proton-Proton Collisions at*\( \sqrt{s} \) = 7*TeV Using the ATLAS Detector*,*Phys. Rev. Lett.***111**(2013) 232002 [arXiv:1307.6511] [INSPIRE]. - [31]CMS collaboration,
*Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC*,*Phys. Lett.***B 716**(2012) 30 [arXiv:1207.7235] [INSPIRE]. - [32]ATLAS collaboration,
*Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC*,*Phys. Lett.***B 716**(2012) 1 [arXiv:1207.7214] [INSPIRE]. - [33]V. Silveira and A. Zee,
*Scalar Phantoms*,*Phys. Lett.***161B**(1985) 136 [INSPIRE].ADSCrossRefGoogle Scholar - [34]R.M. Schabinger and J.D. Wells,
*A minimal spontaneously broken hidden sector and its impact on Higgs boson physics at the large hadron collider*,*Phys. Rev.***D 72**(2005) 093007 [hep-ph/0509209] [INSPIRE]. - [35]D. O’Connell, M.J. Ramsey-Musolf and M.B. Wise,
*Minimal Extension of the Standard Model Scalar Sector*,*Phys. Rev.***D 75**(2007) 037701 [hep-ph/0611014] [INSPIRE]. - [36]O. Bahat-Treidel, Y. Grossman and Y. Rozen,
*Hiding the Higgs at the LHC*,*JHEP***05**(2007) 022 [hep-ph/0611162] [INSPIRE]. - [37]V. Barger, P. Langacker, M. McCaskey, M.J. Ramsey-Musolf and G. Shaughnessy,
*LHC Phenomenology of an Extended Standard Model with a Real Scalar Singlet*,*Phys. Rev.***D 77**(2008) 035005 [arXiv:0706.4311] [INSPIRE]. - [38]G. Bhattacharyya, G.C. Branco and S. Nandi,
*Universal Doublet-Singlet Higgs Couplings and phenomenology at the CERN Large Hadron Collider*,*Phys. Rev.***D 77**(2008) 117701 [arXiv:0712.2693] [INSPIRE]. - [39]M. Gonderinger, Y. Li, H. Patel and M.J. Ramsey-Musolf,
*Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter*,*JHEP***01**(2010) 053 [arXiv:0910.3167] [INSPIRE]. - [40]S. Dawson and W. Yan,
*Hiding the Higgs Boson with Multiple Scalars*,*Phys. Rev.***D 79**(2009) 095002 [arXiv:0904.2005] [INSPIRE]. - [41]S. Bock, R. Lafaye, T. Plehn, M. Rauch, D. Zerwas and P.M. Zerwas,
*Measuring Hidden Higgs and Strongly-Interacting Higgs Scenarios*,*Phys. Lett.***B 694**(2011) 44 [arXiv:1007.2645] [INSPIRE].ADSGoogle Scholar - [42]P.J. Fox, D. Tucker-Smith and N. Weiner,
*Higgs friends and counterfeits at hadron colliders*,*JHEP***06**(2011) 127 [arXiv:1104.5450] [INSPIRE].ADSCrossRefGoogle Scholar - [43]C. Englert, T. Plehn, D. Zerwas and P.M. Zerwas,
*Exploring the Higgs portal*,*Phys. Lett.***B 703**(2011) 298 [arXiv:1106.3097] [INSPIRE].ADSCrossRefGoogle Scholar - [44]C. Englert, J. Jaeckel, E. Re and M. Spannowsky,
*Evasive Higgs Maneuvers at the LHC*,*Phys. Rev.***D 85**(2012) 035008 [arXiv:1111.1719] [INSPIRE]. - [45]B. Batell, S. Gori and L.-T. Wang,
*Exploring the Higgs Portal with 10/fb at the LHC*,*JHEP***06**(2012) 172 [arXiv:1112.5180] [INSPIRE].ADSCrossRefGoogle Scholar - [46]C. Englert, T. Plehn, M. Rauch, D. Zerwas and P.M. Zerwas,
*LHC: Standard Higgs and Hidden Higgs*,*Phys. Lett.***B 707**(2012) 512 [arXiv:1112.3007] [INSPIRE].ADSCrossRefGoogle Scholar - [47]R.S. Gupta and J.D. Wells,
*Higgs boson search significance deformations due to mixed-in scalars*,*Phys. Lett.***B 710**(2012) 154 [arXiv:1110.0824] [INSPIRE].ADSCrossRefGoogle Scholar - [48]G.M. Pruna and T. Robens,
*The Higgs Singlet extension parameter space in the light of the LHC discovery*,*Phys. Rev.***D 88**(2013) 115012 [arXiv:1303.1150] [INSPIRE]. - [49]D. López-Val and T. Robens, Δ
*r and the W-boson mass in the singlet extension of the standard model*,*Phys. Rev.***D 90**(2014) 114018 [arXiv:1406.1043] [INSPIRE]. - [50]T. Robens and T. Stefaniak,
*Status of the Higgs Singlet Extension of the Standard Model after LHC Run 1*,*Eur. Phys. J.***C 75**(2015) 104 [arXiv:1501.02234] [INSPIRE].ADSCrossRefGoogle Scholar - [51]K. Doroba et al.,
*The W*_{L}*W*_{L}*Scattering at the LHC: Improving the Selection Criteria*,*Phys. Rev.***D 86**(2012) 036011 [arXiv:1201.2768] [INSPIRE]. - [52]CMS collaboration,
*Search for a W*′*or Techni-ρ Decaying into W Z in pp Collisions at*\( \sqrt{s} \) = 7*TeV*,*Phys. Rev. Lett.***109**(2012) 141801 [arXiv:1206.0433] [INSPIRE]. - [53]ATLAS collaboration,
*Measurement of W*^{±}*Z production cross sections and gauge boson polarisation in pp collisions at*\( \sqrt{s} \) = 13*TeV with the ATLAS detector*,*Eur. Phys. J.***C 79**(2019) 535 [arXiv:1902.05759] [INSPIRE]. - [54]CMS collaboration, CMS Note AN-2007/05.Google Scholar
- [55]A. Ballestrero, G. Bevilacqua and E. Maina,
*A complete parton level analysis of boson-boson scattering and ElectroWeak Symmetry Breaking in ℓν + four jets production at the LHC*,*JHEP***05**(2009) 015 [arXiv:0812.5084] [INSPIRE].ADSCrossRefGoogle Scholar