Measurements are presented of W gamma gamma and Z gamma gamma production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 inverse femtobarns collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the W to l nu and Z to ll decay modes, where l is a muon or an electron. The production of W gamma gamma and Z gamma gamma, measured with significances of 2.6 and 5.9 standard deviations, respectively, is consistent with standard model predictions. In addition, limits on anomalous quartic gauge couplings in W gamma gamma production are determined in the context of a dimension-8 effective field theory.
The process e+e- -> W+ W- gamma is studied using the data collected by the L3 detector at LEP. New results, corresponding to an integrated luminosity of 427.4 pb-1 at centre-of-mass energies from 192 GeV to 207 GeV, are presented. The W+W- gamma cross sections are measured to be in agreement with Standard Model expectations. No hints of anomalous quartic gauge boson couplings are observed. Limits at 95% confidence level are derived using also the process e+e- --> nu nubar gamma gamma.
We present a search for anomalous components of the quartic gauge boson coupling WWγγ in events with an electron, a positron and missing transverse energy. The analyzed data correspond to 9.7 fb^-1 of integrated luminosity collected by the D0 detector in ppbar collisions at sqrt(s) = 1.96 TeV. The presence of anomalous quartic gauge couplings would manifest itself as an excess of boosted WW events. No such excess is found in the data, and we set the most stringent limits to date on the anomalous coupling parameters a_0^W and a_C^W. When a form factor with Lambda_cutoff = 0.5 TeV is used, the o…
The cross section of the process e^+ e^- -> Z γγ-> qq γγis measured with 215 pb^-1 of data collected with the L3 detector during the final LEP run at centre-of-mass energies around 205 GeV and 207 GeV. No deviation from the Standard Model expectation is observed. The full data sample of 713 pb^-1, collected above the Z resonance, is used to constrain the coefficients of anomalous quartic gauge boson couplings to: -0.02 GeV^-2 < a_0/Λ^2 < 0.03 GeV^-2 and -0.07 GeV^-2 < a_c/Λ^2 < 0.05 GeV^-2, at 95% confidence level.
This paper presents the extended results of measurements of $W^{\pm}W^{\pm}jj$ production and limits on anomalous quartic gauge couplings using 20.3 ${\rm fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two leptons ($e$ or $μ$) with the same electric charge and at least two jets are analyzed. Production cross-sections are determined in two fiducial regions, with different sensitivities to the electroweak and strong production mechanisms. An additional fiducial region, particularly sensitive to anomalous quar…
This Letter reports evidence of triple gauge boson production $pp\to W(\ellν)γγ+ X$, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sample corresponding to an integrated luminosity of 20.3 fb$^{-1}$, collected by the ATLAS detector in 2012. Events are selected using the $W$ boson decay to $eν$ or $μν$ as well as requiring two isolated photons. The measured cross section is used to set limits on anomalous quartic gauge couplings in the high diphoton mass region.
W+W-gamma production at LEP2 is studied using data collected with the DELPHI detector at centre-of-mass energies between 189 GeV and 209 GeV, corresponding to an integrated luminosity of about 600 pb^-1. Cross-sections are measured for the production of W+W- with a hard, central and isolated photon in the final state, and are found to be compatible with the Standard Model prediction. The photon energy spectra are used to derive limits on anomalous contributions to the W+W-Z0gamma and W+W-gammagamma vertices.
The process e+e- -> W+W-gamma is analysed using the data collected with the L3 detector at LEP at a centre-of-mass energy of 188.6GeV, corresponding to an integrated luminosity of 176.8pb^-1. Based on a sample of 42 selected W+W- candidates containing an isolated hard photon, the W+W-gamma cross section, defined within phase-space cuts, is measured to be: sigma_WWgamma = 290 +/- 80 +/- 16 fb, consistent with the Standard Model expectation. Including the process e+e- -> nu nu gamma gamma, limits are derived on anomalous contributions to the Standard Model quartic vertices W+W- gamma gamma and W…
Combined effective field theory interpretation of measurements sensitive to quartic gauge boson couplings in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)（欧洲核子研究组织（CERN））
本文结合ATLAS探测器在13 TeV pp碰撞中对四阶规范玻色子耦合敏感的测量，利用有效场论约束Éboli模型中由维度8算符引起的电弱玻色子四阶自耦合。
A search for exclusive or quasi-exclusive gamma gamma to W+W- production, via pp to p(*) W+W- p(*) to p(*) mu+/- e-/+ at sqrt(s) = 8 TeV, is reported using data corresponding to an integrated luminosity of 19.7 inverse femtobarns. Events are selected by requiring the presence of an electron-muon pair with large transverse momentum pt(mu+/- e-/+) > 30 GeV, and no associated charged particles detected from the same vertex. The 8 TeV results are combined with the previous 7 TeV results (obtained for 5.05 inverse femtobarns of data). In the signal region, 13 (2) events are observed over an expecte…
A search for exclusive or quasi-exclusive W(+)W(-) production by photon-photon interactions, pp to p(*)W(+)W(-)p(*), at sqrt(s) = 7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 inverse femtobarns. Events are selected by requiring a mu(+/-)e(-/+) vertex with no additional associated charged tracks and dilepton transverse momentum pt(mu(+/-)e(-/+)) > 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2 +/- 0.4 signal events with 0.84 +/- 0.15 background. The tail of the di…
A measurement of vector boson scattering and constraints on anomalous quartic gauge couplings from events with two Z bosons and two jets are presented. The analysis is based on a data sample of proton-proton collisions at sqrt(s) = 13 TeV collected with the CMS detector and corresponding to an integrated luminosity of 35.9 inverse femtobarns. The search is performed in the fully leptonic final state ZZ to lll'l', where l, l' = e, mu. The electroweak production of two Z bosons in association with two jets is measured with an observed (expected) significance of 2.7 (1.6) standard deviations. A f…
The search for quartic anomalous gauge couplings at LEP requires appropriate predictions for the radiative processes e+ e- \to ν\barνγγ, e+ e- \to q\bar{q}γγand e+ e- \to 4 fermions+γ. Matrix elements are exactly computed at the tree level, and the effects of anomalous couplings and initial-state radiation are included. Comparisons with results and approximations existing in the literature are shown and commented. Improved versions of the event generators NUNUGPV and WRAP are made available for experimental analysis.
A measurement is presented of the cross section for electroweak production of a Z boson and a photon in association with two jets (Z$γ$jj) in proton-proton collisions. The Z boson candidates are selected through their decay into a pair of electrons or muons. The process of interest, electroweak Z$γ$jj production, is isolated by selecting events with a large dijet mass and a large pseudorapidity gap between the two jets. The measurement is based on data collected at the CMS experiment at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed significance …
A measurement is presented of the cross section for the electroweak production of a Z boson and a photon in association with two jets in proton-proton collisions at sqrt(s)= 8 TeV. The Z bosons are identified through their decays to electron or muon pairs. The measurement is based on data collected with the CMS detector corresponding to an integrated luminosity of 19.7 inverse femtobarns. The electroweak contribution has a significance of 3.0 standard deviations, and the measured fiducial cross section is 1.86 +0.90/-0.75 (stat) +0.34/-0.26 (syst) +/- 0.05 (lumi) fb, while the summed electrowe…
The first observation of the electroweak (EW) production of a Z boson, a photon, and two forward jets (Z$γ$jj) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of 137 fb$^{-1}$, collected by the CMS experiment at the LHC in 2016-2018 is used. The measured fiducial cross section for EW Z$γ$jj is $σ_{\mathrm{EW}}$ = 5.21 $\pm$ 0.52 (stat) $\pm$ 0.56 (syst) fb = 5.21 $\pm$ 0.76 fb. Single-differential cross sections in photon, leading lepton, and leading jet transverse momenta, and double-differential cross section…
A search for WV gamma triple vector boson production is presented based on events containing a W boson decaying to a muon or an electron and a neutrino, a second V (W or Z) boson, and a photon. The data correspond to an integrated luminosity of 19.3 inverse femtobarns collected in 2012 with the CMS detector at the LHC in pp collisions at sqrt(s) = 8 TeV. An upper limit of 311 fb on the fiducial cross section for the WV gamma production process is obtained at 95% confidence level for photons with a transverse energy above 30 GeV and with an absolute value of pseudorapidity of less than 1.44. Th…
The cross section for W or Z boson production in association with two photons is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data set corresponds to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS experiment at the LHC. The W $\to$ $\ellν$ and Z $\to$ $\ell\ell$ decay modes (where $\ell =$ e, $μ$) are used to extract the W$γγ$ and Z$γγ$ cross sections in a phase space defined by electron (muon) with transverse momentum larger than 30 GeV and photon transverse momentum larger than 20 GeV. All leptons and photons are required to have absolute pse…
Measuring the shape of the Higgs boson potential is of paramount importance and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range, and luminosities of the order of 10^35cm^-2s^-1, as presently under discussio…
This paper presents a study of $WWγ$ and $WZγ$ triboson production using events from proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV recorded with the ATLAS detector at the LHC and corresponding to an integrated luminosity of 20.2 fb$^{-1}$. The $WWγ$ production cross-section is determined using a final state containing an electron, a muon, a photon, and neutrinos ($eνμνγ$). Upper limits on the production cross-section of the $eνμνγ$ final state and the $WWγ$ and $WZγ$ final states containing an electron or a muon, two jets, a photon, and a neutrino ($eνjjγ$ or $μνjj…
We study the $W/Z$ pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and $W/Z$ bosons for an integrated luminosity of 30 and 200 fb$^{-1}$. For simplicity and to obtain lower backgrounds, only the leptonic decays of the electroweak bosons are considered. The intact protons in the final states are detected in the ATLAS Forward Proton detectors. The high energy and luminosity of the LHC and the forward detectors allow to probe beyond standard model physics and to test the higgsless and extra dimension …
A study of W+W- events accompanied by hard photon radiation produced in e+e- collisions at LEP is presented. Events consistent with two on-shell W-bosons and an isolated photon are selected from 183pb^-1 of data recorded at root{s}=189GeV. From these data, 17 W+W-gamma candidates are selected with photon energy greater than 10GeV, consistent with the Standard Model expectation. These events are used to measure the e+e- to W+W-gamma cross-section within a set of geometric and kinematic cuts; sigma{W+W-gamma} = 136+-37+-8 fb, where the first error is statistical and the second systematic. The ph…
Observation of $W^{+}W^{-}γ$ production in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector and constraints on anomalous quartic gauge-boson couplings
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)（欧洲核子研究中心）
Triple gauge boson production provides a promising opportunity to probe the anomalous quartic gauge couplings in understanding the details of electroweak symmetry breaking at future hadron-hadron collider facilities with increasing center of mass energy and luminosity. In this paper, we investigate the sensitivities of dimension-8 anomalous couplings related to the $ZZγγ$ and $Zγγγ$ quartic vertices, defined in the effective field theory framework, via $pp\to Zγγ$ signal process with Z-boson decaying to charged leptons at the high luminosity phase of LHC (HL-LHC) and future facilities, namely …
The anomalous quartic neutral couplings of the $γγγγ$ vertex in a polarized light-by-light scattering of the Compton backscattered photons at the CLIC are examined. Both differential and total cross sections are calculated for $e^+e^-$ collision energies 1500 GeV and 3000 GeV. The helicity of the initial electron beams is taken to be $\pm\,0.8$. The unpolarized and SM cross sections for the same values of helicities are also estimated. The 95\% C.L. exclusion limits on two anomalous photon couplings $ζ_1$ and $ζ_2$ are calculated. The best bounds on these couplings are found to be $6.85 \times…
A measurement of electroweak-induced production of W gamma and two jets is performed, where the W boson decays leptonically. The data used in the analysis correspond to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS experiment in sqrt(s) = 8 TeV proton-proton collisions produced at the LHC. Candidate events are selected with exactly one muon or electron, missing transverse momentum, one photon, and two jets with large rapidity separation. An excess over the hypothesis of the standard model without electroweak production of W gamma with two jets is observed with a sign…
We obtain the partial-wave unitarity constraints on the lowest-dimension effective operators which generate anomalous quartic gauge couplings but leave the triple gauge couplings unaffected. We consider operator expansions with linear and nonlinear realizations of the electroweak symmetry and explore the multidimensional parameter space of the coefficients of the relevant operators: 20 dimension-eight operators in the linear expansion and 5 ${\cal O}(p^4)$ operators in the derivative expansion. We study two-to-two scattering of electroweak gauge bosons and Higgs bosons taking into account all …
The exclusive two-photon production at the LHC of pairs of W and Z bosons provides a novel and unique test-ground for the electroweak gauge boson sector. In particular it offers, thanks to high gamma-gamma center-of-mass energies, large and direct sensitivity to the anomalous quartic gauge couplings otherwise very difficult to investigate at the LHC. An initial analysis has been performed assuming leptonic decays and generic acceptance cuts. Simulation of a simple counting experiment has shown for the integrated luminosity of 10 fb-1 at least four thousand times larger sensitivity to the genui…
Vector boson scattering and anomalous quartic couplings in final states with $\ellν$qq or $\ell\ell$qq plus jets using proton-proton collisions at $\sqrt{s}$ = 13 TeV
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)（欧洲核子研究组织（CERN））
We study the indirect constraints on the quartic Higgs self-coupling that arise from double-Higgs production at future hadron colliders. To this purpose, we calculate the two-loop contributions to the $gg \to hh$ amplitudes that involve a modified $h^4$ vertex. Based on our results, we estimate the reach of a $pp$ collider operating at $27 \, {\rm TeV}$ and $100 \, {\rm TeV}$ centre-of-mass energy in constraining the cubic and quartic Higgs self-couplings by measurements of double-Higgs and triple-Higgs production in gluon-fusion.
Gauge boson self-couplings are exactly determined by the non-Abelian gauge nature of the Standard Model (SM), thus precision measurements of these couplings at the LHC provide an important opportunity to test the gauge structure of the SM and the spontaneous symmetry breaking mechanism. It is a common way to examine the physics of anomalous quartic gauge boson couplings via effective Lagrangian method. In this work, we investigate the potential of the process $pp\rightarrow pγp\rightarrow p W Z q X$ to analyze anomalous quartic $WWZγ$ couplings by two different CP-violating and CP-conserving e…
Measurement of electroweak $Z(ν\barν)γjj$ production and limits on anomalous quartic gauge couplings in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
Recent measurements of multiboson production from the CMS experiment will be presented, as well as limits on anomalous triple and quartic gauge couplings. Precision measurements of multiboson production allow a basic test of the Standard Model, where higher order QCD and electroweak corrections can be probed. In addition searches of physics beyond the Standard Model in multiboson final states rely on precise determination of the Standard Model multiboson processes. The presence of triple and quartic gauge couplings in multiboson production also allows for tests of modification of these vertice…
We present results from a search for anomalous WW and WZ production in ppbar collisions at sqrt(s) = 1.8 TeV. We used ppbar->evjjX events observed during the 1992-1993 run of the Fermilab Tevatron collider, corresponding to an integrated luminosity of 13.7 +- 0.7 pb^-1. A fit to the transverse momentum spectrum of the W boson yields direct limits on the CP-conserving anomalous WWgamma and WWZ coupling parameters of -0.9 < delta kappa < 1.1 (with lambda = 0) and -0.6 < lambda < 0.7 (with delta kappa = 0) at the 95% confidence level, for a form factor scale Lambda = 1.5 TeV, assuming that the WW…
We present a search for anomalous triple gauge couplings (ATGC) in WW and WZ boson production. The boson pairs are produced in ppbar collisions at sqrt{s}=1.96 TeV, and the data sample corresponds to 350 pb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. In this search one W decays to leptons, and the other boson (W or Z) decays hadronically. Combining with a previously published CDF measurement of Wgamma boson production yields ATGC limits of -0.18 < lambda < 0.17 and -0.46 < Delta kappa < 0.39 at the 95% confidence level, using a cut-off scale Lambda=1…
We present the first observation of the Zgamma to nunugamma process at the Tevatron at 5.1 standard deviations significance, based on 3.6 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron ppbar Collider at sqrt{s} = 1.96 TeV. The measured Zgamma cross section multiplied by the branching fraction of Z to nunu is 32 +- 9 (stat.+syst.) +- 2 (lumi.) fb for the photon ET > 90 GeV. It is in agreement with the standard model prediction of 39 +- 4 fb. We set the most restrictive limits on anomalous trilinear Zgammagamma and ZZgamma gauge boson couplings at a hadron …
We present a measurement of the Zγproduction cross section and limits on anomalous ZZγand Zγγcouplings for form-factor scales of Lambda = 750 and 1000 GeV. The measurement is based on 138 (152) candidate events in the eeγ(μμγ) final state using 320 (290) pb^{-1} of ppbar collisions at \sqrt{s} = 1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are |h_{10,30}^{Z}|<0.23, |h_{20,40}^{Z}|<0.020, |h_{10,30}^γ|<0.23, and |h_{20,40}^γ|<0.019 for Lambda = 1000 GeV.
We present new direct constraints on a general $Wtb$ interaction using data corresponding to an integrated luminosity of 5.4 fb$^{-1}$ collected by the D0 detector at the Tevatron $p\bar{p}$ collider. The standard model provides a purely left-handed vector coupling at the $Wtb$ vertex, while the most general, lowest dimension Lagrangian allows right-handed vector and left- or right-handed tensor couplings as well. We obtain precise limits on these anomalous couplings by comparing the data to the expectations from different assumptions on the $Wtb$ coupling.
Limits are set on anomalous WWgamma and WWZ trilinear gauge couplings using W+W- -> e+e-, W+W- -> e mu, and W+W- -> mu+mu- events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250 inverse pb of integrated luminosity at sqrt(s) = 1.96 TeV. Under the assumption that the WWgamma couplings are equal to the WWZ couplings and using a form factor scale of Lambda = 2.0 TeV, the combined 95% C.L. one-dimensional coupling limits from all three channels are -0.32 < Delta kappa < 0.45 and -0.29 < lambda < 0.30.
We present results from a study of p-pbar -> W(gamma) + X events utilizing data corresponding to 0.7 fb^{-1} of integrated luminosity at sqrt(s) = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We set limits on anomalous WWgamma couplings at the 95% C.L. The one dimensional 95% C.L. limits are 0.49 < kappa_{gamma} < 1.51 and -0.12 < lambda_{gamma} < 0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the Wgamma system.
Composite effective field theory signal from anomalous quartic gauge couplings for $ZZ(\rightarrow\ell\ellνν)jj$ and $Zγ(\rightarrowννγ)jj$ productions
The WZ production cross section is measured by the CMS experiment at the CERN LHC in proton-proton collision data samples corresponding to integrated luminosities of 4.9 inverse femtobarns collected at sqrt(s)= 7 TeV, and 19.6 inverse femtobarns at sqrt(s)= 8 TeV. The measurements are performed using the fully-leptonic WZ decay modes with electrons and muons in the final state. The measured cross sections for 71 < m[Z] < 111 GeV are sigma(pp to WZ; sqrt(s)= 7 TeV) = 20.14 +/- 1.32 (stat) +/- 1.13 (syst) +/- 0.44 (lumi) pb and sigma(pp to WZ; sqrt(s)= 8 TeV) = 24.09 +/- 0.87 (stat) +/- 1.62 (sy…
The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gam…
In this paper, we examine the potentials of the processes $γγ\rightarrow W^{+} W^{-}Z $ and $e^{+}e^{-} \rightarrow e^{+}γ^{*} γ^{*} e^{-} \rightarrow e^{+} W^{+} W^{-} Z e^{-}$ at the CLIC with $\sqrt{s}=0.5,1.5$ and $3$ TeV to investigate anomalous quartic $WWZγ$ couplings by two different CP-violating and CP-conserving effective Lagrangians. We find $95\%$ confidence level limits on the anomalous coupling parameters at the three CLIC energies and various integrated luminosities. The best limits obtained from the process $γγ\rightarrow W^{+} W^{-}Z $ on the anomalous $\frac{k_{0}^{W}}{Λ^{2}}…
We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb^-1 collected with the D0 detector at sqrt{s} =1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c^2. The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb pro…
We present results from a search for WZ production with subsequent decay to l nu l'-bar l' (l and l'=electron or muon) using 0.30 fb^(-1) of data collected by the DO experiment between 2002 and 2004 at the Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71+-0.08 events, we measure the WZ production cross section to be 4.5 (+3.8 -2.6) pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0 < Delta kappa_Z < 2.4 for form factor scale Lambda = 1 TeV, and -0.48 < lambda_Z < 0.48 and -0.49 …
Gluon-gluon to photon-photon scattering $gg \to γγ$ offers to the LHC experiments a uniquely powerful probe of dimension-8 operators in the Standard Model Effective Field Theory (SMEFT) that are quadratic in both the electromagnetic and gluonic field-strength tensors, such as would appear in the Born-Infeld extension of the Standard Model (SM). We use 13-TeV ATLAS data on the production of isolated photon pairs to set lower limits on the scales of dimension-8 operators $M \gtrsim 1$~TeV, and discuss the prospective sensitivities of possible future hadron colliders.
Probing anomalous quartic gauge couplings in same-sign $W$ boson scattering with polarization and spin correlation
Instituto de Física, Universidade de São Paulo（圣保罗大学物理研究所）；Wilczek Quantum Center, Shanghai Institute for Advanced Studies（上海高等研究院费曼量子中心）；University of Science and Technology of China（中国科学技术大学）
Quartic gauge couplings are tested by this study of the production of $WWγ$ and $WZγ$ events in 20.2 fb$^{-1}$ of proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV recorded with the ATLAS detector at the LHC. The final state of $WWγ$ events containing an electron, a muon and a photon is analysed as well as the final states of $WWγ$ and $WZγ$ production containing an electron or a muon, two jets and a photon. For all final states two different fiducial regions are defined: one yielding the best sensitivity to the production cross-section of the process and one optimised…
We present a measurement of ppbar->Zgamma->ll+gamma (l = e, mu) production with a data sample corresponding to an integrated luminosity of 6.2 fb^{-1} collected by the D0 detector at the Fermilab Tevatron ppbar Collider. The results of the electron and muon channels are combined, and we measure the total production cross section and the differential cross section dsigma/dp_T^gamma, where p_T^gamma is the momentum of the photon in the plane transverse to the beamline. The results obtained are consistent with the standard model predictions from next-to-leading order calculations. We use the tran…
This Letter presents a search for new physics manifested as anomalous triple gauge boson couplings in WW and WZ diboson production in proton-proton collisions. The search is performed using events containing a W boson that decays leptonically and a W or Z boson whose decay products are merged into a single reconstructed jet. The data, collected at sqrt(s) = 8 TeV with the CMS detector at the LHC, correspond to an integrated luminosity of 19 inverse femtobarns. No evidence for anomalous triple gauge couplings is found and the following 95% confidence level limits are set on their values: lambda…
We present a new measurement of the $WZ\rightarrow \ellν\ell\ell$ ($\ell = e,μ$) cross section and limits on anomalous triple gauge couplings. Using 4.1 fb$^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV, we observe 34 $WZ$ candidate events with an estimated background of $6.0 \pm 0.4$ events. We measure the $WZ$ production cross section to be $3.90^{+1.06}_{-0.90}$ pb, in good agreement with the standard model prediction. We find no evidence for anomalous $WWZ$ couplings and set 95% C.L. limits on the coupling parameters, $-0.075 < λ_{Z} < 0.093$ and $-0.027 …
We present a study of Z +gamma + X production in p-bar p collisions at sqrt{S}=1.8 TeV from 97 (87) pb^{-1} of data collected in the eegamma (mumugamma) decay channel with the D0 detector at Fermilab. The event yield and kinematic characteristics are consistent with the Standard Model predictions. We obtain limits on anomalous ZZgamma and Zgammagamma couplings for form factor scales Lambda = 500 GeV and Lambda = 750 GeV. Combining this analysis with our previous results yields 95% CL limits |h{Z}_{30}| < 0.36, |h{Z}_{40}| < 0.05, |h{gamma}_{30}| < 0.37, and |h{gamma}_{40}| < 0.05 for a form fa…
A complete list of operators contributing at the lowest order to Quartic Neutral Gauge Boson Couplings involving photons and Z-bosons, is presented. We show that, for the couplings we consider, the lowest order contribution is from dimension 8 operators in the case when a light Higgs is present and from dimension 6 operators in the higgsless case where electroweak symmetry is non-linearly realized. We also show that these operators are generated by exchange of the Kaluza-Klein partners of the graviton in extra-dimensional models. We then explore the possibility of probing these couplings in th…
We provide the most precise measurement of the WW production cross section in p-pbar collisions to date at a center of mass energy of 1.96 TeV, and set limits on the associated trilinear gauge couplings. The WW->lvl'v (l,l'=e,mu) decay channels are analyzed in 1 fb^(-1) of data collected by the D0 detector at the Fermilab Tevatron Collider. The measured cross section is sigma(p-pbar -> WW) = 11.5 +/- 2.1 (stat + syst) +/- 0.7 (lumi) pb. One- and two-dimensional 95% C.L. limits on trilinear gauge couplings are provided.
A search is presented for three additional operators that would lead to anomalous WW$γ$ or WWZ couplings with respect to those in the standard model. They are constrained by studying events with two vector bosons; a W boson decaying to e$ν$ or $μν$, and a W or Z boson decaying hadronically, reconstructed as a single, massive, large-radius jet. The search uses a data set of proton-proton collisions at a centre-of-mass energy of 13 TeV, recorded by the CMS experiment at the CERN LHC in 2016, and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Using the reconstructed diboson invarian…
This Letter reports a measurement of the WW production cross section in sqrt(s) = 7 TeV pp collisions using data corresponding to an integrated luminosity of 1.02/fb collected with the ATLAS detector. Using leptonic decays of oppositely charged W bosons, the total measured cross section is sigma(pp -> WW) = 54.4 +/- 4.0 (stat.) +/- 3.9 (syst.) +/- 2.0 (lumi.) pb, consistent with the Standard Model prediction of sigma(pp -> WW) = 44.4 +/- 2.8 pb. Limits on anomalous electroweak triple-gauge couplings are extracted from a fit to the transverse-momentum distribution of the leading charged lepton …
We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Deltaκ_γ, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. …
