Anomalous Quartic Couplings Research Articles

Precision physics with the proton spectrometer and diffractive physics measurements from CMS

We describe recent results from CMS and TOTEM on hard diffraction, diffractive jets and jet gap jet events. We also give the first sensitivities and limits on quartic anomalous couplings and axion-like particles at high mass using the LHC as a \gamma \gammaγγ collider. The predicted sensitivities with 300 fb^{-1}−1 are better by two or three orders of magnitude compared to the more standard methods at the LHC without measuring intact protons after collision.

Bounds on quartic gauge couplings in HEFT from electroweak gauge boson pair production at the LHC

Precision measurements of anomalous quartic couplings of electroweak gauge bosons allow us to search for deviations of the Standard Model predictions and signals of new physics. Here, we obtain the constraints on anomalous quartic gauge couplings using the presently available data on the production of gauge-boson pairs via vector boson fusion. We work in the Higgs effective theory framework and obtain the present bounds on the operator’s Wilson coefficients. We show that the combination of different datasets breaks the degeneracies in analysis with more than one nonvanishing Wilson coefficient. Anomalous quartic gauge boson couplings lead to rapidly growing cross sections and we discuss the impact of a unitarization procedure on the attainable limits. Published by the American Physical Society 2024

Search for the anomalous quartic gauge couplings through Z γ production at e − e + colliders

Spontaneous breaking of the electroweak symmetry of the standard model (SM) sets the constraints on triple and quartic gauge couplings. Therefore, the measurement of multiboson production in e − e + collisions allows us to directly test the predictions of the SM and to indirectly probe new physics beyond the SM. In this paper, we focus on the process e − e + → e − Z γ e + with Z boson decaying into neutrinos to study the anomalous quartic gauge couplings using the effective Lagrangian approach at the compact linear collider (CLIC). We obtain the sensitivities on the anomalous f T,i /Λ4 (i = 0, 2, 5, 6, 7, 8, 9) couplings taking into account the systematic uncertainties of 3, 5% at 95% Confidence Level for the CLIC with TeV. Our results show that the sensitivities on some anomalous couplings without systematic errors are up to two orders of magnitude better than the current experimental limits. Considering a realistic systematic uncertainty such as 5% from possible experimental sources, the sensitivity of all anomalous quartic couplings becomes worse by about 10% compared to those without systematic uncertainty for the CLIC.

Sensitivity of anomalous quartic gauge couplings via tri-photon production at FCC-hh

A direct investigation of the self-couplings of gauge bosons, completely described by the non-Abelian gauge symmetry of the Standard Model, is extremely valuable in understanding the gauge structure of the SM. Any deviation from the SM predictions on gauge boson self-coupling is to give a hint at the existence of a new physics beyond the SM, which is defined with a modification of the self-interactions using an effective field theory approach. In this paper, we present a detailed Monte Carlo study searching for anomalous quartic gauge dimension-8 couplings related to γγγγ and γγγZ vertices at the future hadron-hadron collider (FCC-hh) via tri-photon production at a 100 TeV center of mass energy with an integrated luminosity Lint =30 ab−1. Events that have been parton showered and include detector effects are analyzed with a Toolkit for Multivariate Data Analysis (TMVA) using a boosted decision tree to help distinguish between signal and background events to achieve the best sensitivities on anomalous quartic gauge couplings. Our obtained results reveal that the limits on anomalous quartic gauge couplings fT8/Λ4 and fT9/Λ4 at 95% C.L. without systematic errors are about three orders of magnitude stronger compared to the best current experimental limits reported by the ATLAS collaboration at the LHC. Considering a realistic systematic uncertainty such as 10% from possible experimental sources, our obtained limits of anomalous quartic couplings get worse by about one order of magnitude compared to those without systematic uncertainty but are still two orders of magnitude better than those recently reported by ATLAS.

Physics with intact protons at the LHC: from the odderon discovery to the sensitivity to beyond standard model physics

We describe the discovery of the colorless C-odd gluonic compound, the odderon, by the D0 and TOTEM Collaborations by comparing elastic differential cross sections measured in pp and pp¯ interactions at high energies. We also discuss the reach on quartic anomalous couplings and the sensitivity to axion like particle production by using the LHC as a γγ collider and detecting the intact protons at high luminosity.

Study of the projected sensitivity on the anomalous quartic gauge couplings via Zγγ production at the CLIC

Gauge boson self-couplings are completely defined by the non-Abelian gauge symmetry of the Standard Model (SM). For this reason, a direct search for these couplings is extremely significant in understanding the gauge structure of the SM. The possible deviation from the SM predictions of gauge boson self-couplings would be a sign of the presence of new physics beyond the SM. In this work, we study the sensitivities on the anomalous couplings defined by dimension-8 operators related to the $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$ quartic vertices through the process $e^+e^- \to Z\gamma\gamma$ with Z-boson decaying to charged leptons at the Compact Linear Collider (CLIC). We analyze the center-of-mass energy of 3 TeV, integrated luminosities of ${\cal L}=1, 4, 5$ $\rm ab^{-1}$, systematic uncertainties of $\delta_{sys}=0\%, 3\%, 5\%$, unpolarized and polarized electron beams and considering the Initial State Radiation and Beamstrahlung effects for extraction of expected sensitivity on the anomalous $f_ {T,j}/\Lambda^4$ couplings at $95\%$ confidence level, which are especially sensitive to the $Z\gamma\gamma$ channel. It is clear from the results that we expect better limits on the couplings if the systematic error is improved. The best limits obtained on the anomalous quartic couplings for the process $e^+e^- \to Z\gamma\gamma$ with $\sqrt{s}= 3$ TeV, ${\cal L}=5$ $\rm ab^{-1}$, and $\delta_{sys}=0\%$ can be approximately improved up to about 1.1 times better than the limits obtained with $\delta_{sys}=5\%$. Our sensitivities on the anomalous quartic couplings can set more stringent sensitivity by two orders of magnitude concerning the best sensitivity derived from the current experimental limits. Finally, with initial electron beam polarization, the sensitivity of the anomalous quartic couplings improves by almost a factor of 1.2.

Bounds on anomalous quartic WWZγ couplings in e – p collisions at the FCC-he

Non-Abelian structure of the standard model (SM) predicts the self-interactions of gauge bosons triple gauge couplings (TGC) and quartic gauge couplings (QGC). On the other hand, it is also important to determine the deviations from SM via anomalous triple gauge couplings and anomalous quartic gauge couplings (aQGC) to test the nature of the SM and to see the effects of new physics arising from the beyond the standard model. In this study, we focus on the e − p → jZ γ ν e → j(l + l −)γ ν e process to examine the WWZ γ aQGC at the Future Circular Collider-hadron electron with center-of-mass energy TeV using a model-independent way in the effective theory approach. A Cut-based method is applied to analyse the signal and relevant SM background. Using the total cross-sections, we constrained the anomalous f T,i=0,1,2,5,6,7/Λ4 couplings arising from dimension-8 operators at 95% confidence level for the dilepton decay of the Z-boson. The results are composed of integrated luminosities of and 3 ab −1 under the systematic uncertainties of 0%, 5% and 10%. In the calculations, we use the form factor to eliminate the effects of the violation of unitarity. With this, we obtained the limits for the energy scale of the form factor Λ = 1 TeV. In addition to all this, we use the advantages of ep collisions for analysing the process with much cleaner environment and lower background effects compared with the pp collisions. The obtained sensitivities on f T, i=0, 1, 2, 5, 6, 7/Λ4 are comparable with the experimental results and related phenomenological studies in the literature.

Future projections on the anomalous WWγγ couplings in hadron–hadron interactions at the FCC-hh

We carry out a study in the approach of a dimension-eight effective field theory on the anomalous quartic WWγγ couplings that arise from the process pp → Wγγ at the Future Circular Collider-hadron hadron (FCC-hh). The process is sensitive to the WWγγ vertex, and future projections on the anomalous f M,i /Λ4 and f T,j /Λ4 couplings can be put by measurements of Wγγ production. We illustrate the physics opportunities and reach of the FCC-hh operating for a high integrated luminosity scenario of of proton–proton collisions at a center-of-mass energy of TeV and systematic uncertainties of δ sys = 0%, 3%, 5%, 10%. Production cross-sections of the signal and the sensitivity constraints on the anomalous f M,i /Λ4 and f T,j /Λ4 couplings at 95% C.L. are identified through the leptonic and hadronic decay modes of the W-boson. The FCC-hh sensitivity on these anomalous couplings is expected might reach up to the order of magnitude . These sensitivity perspectives indicate that the pp → Wγγ channel at the FCC-hh has a greater potential to search for the anomalous quartic WWγγ couplings and to search for new physics than present colliders.

Sensitivity of anomalous quartic gauge couplings via Zγγ production at future hadron-hadron colliders

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→Zγγ signal process with Z-boson decaying to charged leptons at the high luminosity phase of LHC (HL-LHC) and future facilities, namely the High Energy LHC (HE-LHC) and Future Circular hadron-hadron collider (FCC-hh). We analyzed the signal and relevant backgrounds via a cut based method with Monte Carlo event sampling where the detector responses of three hadron collider facilities, the center-of-mass energies of 14, 27 and 100 TeV with integrated luminosities of 3, 15 and 30ab−1 are considered for the HL-LHC, HE-LHC and FCC-hh, respectively. The reconstructed 4-body invariant mass of l+l−γγ system is used to constrain the anomalous quartic gauge coupling parameters under the hypothesis of absence of anomalies in triple gauge couplings. Our results indicate that the sensitivity on anomalous quartic couplings fT8/Λ4 and fT9/Λ4 (fT0/Λ4, fT1/Λ4 and fT2/Λ4) at 95% C.L. for FCC-hh with Lint=30ab−1 without systematic errors is two (one) order better than the current experimental limits. Considering a realistic systematic uncertainty such as 10% from possible experimental sources, the sensitivity of all anomalous quartic couplings gets worsen by about 1.2%, 1.7% and 1.5% compared to those without systematic uncertainty for HL-LHC, HE-LHC and FCC-hh, respectively.

Studies on dimension-eight genuine Quartic Boson Coupling operators

Vector Boson Scattering (VBS) processes provide a great source of information on the structure of the Quartic Gauge Boson Couplings (QGCs). The Standard Model allows self interactions of the charged vector gauge bosons, although vertices with neutral-only bosons are forbidden. In this paper we use Monte Carlo samples containing VBS events with two Z-bosons in association with two jets, and we present preliminary studies for the setting of constraints on anomalous quartic couplings. In these studies we investigate typical kinematic variables and we classify them according to their sensitivity to aQGC effects. Finally, we evaluate the cross-section enhancement by each one of the dimension-eight QGC operators in the ZZjj channel.

Probing anomalous quartic gamma gamma gamma gamma couplings in light-by-light collisions at the CLIC

The anomalous quartic neutral couplings of the gamma gamma gamma gamma 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 zeta _1 and zeta _2 are calculated. The best bounds on these couplings are found to be 6.85 times 10^{-16} text { GeV}^{-4} and 1.43 times 10^{-15} text { GeV}^{-4}, respectively. The results are compared with the exclusion bounds obtained previously for the LHC and HL-LHC. It is shown that the light-by-light scattering at the CLIC, especially the polarized, has a greater potential to search for the anomalous quartic neutral couplings of the gamma gamma gamma gamma vertex.

Analysis of the anomalous quartic WWWW couplings at the LHeC and the FCC-he

The quartic gauge boson couplings that identify the strengths of the gauge boson self-interactions are exactly determined by the non-Abelian gauge nature of the Standard Model. The examination of these couplings at $ep$ collisions with high center-of-mass energy and high integrated luminosity provides an important opportunity to test the validity of the Standard Model and the existence of new physics beyond the Standard Model. The quartic gauge boson couplings can contribute directly to multi-boson production at colliders. Therefore, we examine the potential of the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron to study non-standard $WWWW$ couplings in a model independent way by means of the effective Lagrangian approach. We present an investigation on measuring $W^{+}W^{-}$ production in pure leptonic and semileptonic decay channels. In addition, we calculate the sensitivity limits at $95\%$ Confidence Level on the anomalous $\frac{f_{M0}}{\Lambda^{4}}$, $\frac{f_{M1}}{\Lambda^{4}}$, $\frac{f_{M7}}{\Lambda^{4}}$, $\frac{f_{S0}}{\Lambda^{4}}$, $\frac{f_{S1}}{\Lambda^{4}}$, $\frac{f_{T0}}{\Lambda^{4}}$, $\frac{f_{T1}}{\Lambda^{4}}$ and $\frac{f_{T2}}{\Lambda^{4}}$ couplings obtained by dimension-8 operators through the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ for the Large Hadron Electron Collider and the Future Circular Hadron Electron Collider's different center-of-mass energies and integrated luminosities. Our results show that with the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron the sensitivity estimated on the anomalous $WWWW$ couplings can be importantly strengthened.

Sensitivity physics expected to the measurement of the quartic WWγγ couplings at the LHeC and the FCC-he

We explore the physics expected sensitivity at the Large Hadron electron Collider (LHeC) and the future circular collider-hadron electron (FCC-he) to search for the anomalous quartic WWγγ couplings in single W-boson production in association with a photon. We study the process ep → e−γ*p → eWγq′X via the subprocess γ*q → Wγq′. The center-of-mass energies and luminosities of the LHeC are assumed to be TeV, and for the FCC-he TeV and . Considering these energies and luminosities, we estimate sensitivity measures on the anomalous quartic WWγγ couplings at 95% C.L., which can be an order of magnitude more stringent than the experimental limits reported by ATLAS and CMS Collaborations at the LHC.

Optimal observables for the measurement of anomalous quartic gauge boson couplings

We present a study for the measurement of possible anomalous quartic gauge couplings (aQGCs) in simulated proton-proton collisions at center-of-mass energy TeV with two Z bosons and two jets in the final state where the two bosons decay to charged leptons (). One of the processes resulting in this final state is the Vector Boson Scattering (VBS), which involves the scattering of intermediate vector bosons emitted by the colliding quarks. In the Effective Field Theory approach the VBS cross section depends quadratically on the anomalous quartic couplings and consequently there exist optimal observables which retain the whole kinematical information of the process with respect to the anomalous couplings. We investigate the utilization of these optimal observables in mono-parametric models and we compare their sensitivity with respect to other kinematical variables (e.g the invariant mass of the ZZ system).

Model independent study for the anomalous quartic WWγγ couplings at future electron-proton colliders

The Large Hadron Electron Collider and the Future Circular Collider-hadron electron with high center-of-mass energy and luminosity allow to better understand the Standard Model and to examine new physics beyond the Standard Model in the electroweak sector. Multi-boson processes permit for a measurement of the gauge boson self-interactions of the Standard Model that can be used to determine the anomalous gauge boson couplings. For this purpose, we present a study of the process ep→νeγγj at the Large Hadron Electron Collider with center-of-mass energies of 1.30, 1.98 TeV and at the Future Circular Collider-hadron electron with center-of-mass energies of 7.07, 10 TeV to interpret the anomalous quartic WWγγ gauge couplings using a model independent way in the framework of effective field theory. We obtain the sensitivity limits at 95% Confidence Level on 13 different anomalous couplings arising from dimension-8 operators. The best limit in fMi/Λ4 (i=0,1,2,3,4,5,7) parameters is obtained for fM2/Λ4 parameter while the best sensitivity derived on fTi/Λ4 (i=0,1,2,5,6,7) parameters is obtained for fT5/Λ4. In addition, this study is the first report on the anomalous quartic couplings determined by effective Lagrangians at ep colliders.

Measurement of the cross section for electroweak production of a Z boson, a photon and two jets in proton-proton collisions at sqrt{mathrm{s}} = 13 TeV and constraints on anomalous quartic couplings

A measurement is presented of the cross section for electroweak production of a Z boson and a photon in association with two jets (Zγjj) 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 Zγjj 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 of the signal is 3.9 standard deviations, where a significance of 5.2 standard deviations is expected in the standard model. These results are combined with published results by CMS at sqrt{s} = 8 TeV, which leads to observed and expected respective significances of 4.7 and 5.5 standard deviations. From the 13 TeV data, a value is obtained for the signal strength of electroweak Zγjj production and bounds are given on quartic vector boson interactions in the framework of dimension-eight effective field theory operators.

Measurement of vector boson scattering and constraints on anomalous quartic couplings from events with four leptons and two jets in proton–proton collisions at [formula omitted

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 s=13 TeV collected with the CMS detector and corresponding to an integrated luminosity of 35.9 fb−1. The search is performed in the fully leptonic final state ZZ→ℓℓℓ′ℓ′, where ℓ,ℓ′=e or μ. 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 fiducial cross section for the electroweak production is measured to be σEW(pp→ZZjj→ℓℓℓ′ℓ′jj)=0.40−0.16+0.21(stat)−0.09+0.13(syst) fb, which is consistent with the standard model prediction. Limits on anomalous quartic gauge couplings are determined in terms of the effective field theory operators T0, T1, T2, T8, and T9. This is the first measurement of vector boson scattering in the ZZ channel at the LHC.

Probe of the Anomalous Quartic Couplings with Beam Polarization at the CLIC

We have investigated the anomalous quartic couplings defined by the dimension-8 operators in semileptonic decay channel of thee+e-→νeW-W+ν-eprocess for unpolarized and polarized electron (positron) beam at the Compact Linear Collider. We give the 95% confidence level bounds on the anomalousfS0/Λ4,fS1/Λ4, andfT0/Λ4couplings for various values of the integrated luminosities and center-of-mass energies. The best sensitivities obtained on anomalousfS0/Λ4,fS1/Λ4, andfT0/Λ4couplings through the processe+e-→νeW-W+ν-ewith beam polarization ats=3 TeV and an integrated luminosity ofLint=2000 fb-1are[-4.05;3.67]×10-12 GeV-4,[-3.08;2.12]×10-12 GeV-4, and[-1.98;0.64]×10-13 GeV-4, which show improvement over the current bounds.

Measurements ofZγandZγγproduction inppcollisions ats=8 TeVwith the ATLAS detector

The production of $Z$ bosons with one or two isolated high-energy photons is studied using $pp$ collisions at $\sqrt{s}$ = 8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb$^{-1}$ collected by the ATLAS detector during the 2012 LHC data taking. The $Z\gamma$ and $Z\gamma\gamma$ production cross sections are measured with leptonic ($e^{+}e^{-}$, $\mu^{+}\mu^{-}$, $\nu\bar{\nu}$) decays of the $Z$ boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative $Z$-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy $E_T >$ 250 GeV from $\ell^{+}\ell^{-}\gamma$ events and with $E_T >$ 400 GeV from $\nu\bar{\nu}\gamma$ events are used to search for anomalous triple gauge-boson couplings $ZZ\gamma$ and $Z\gamma\gamma$. The yields of events with diphoton invariant mass $m_{\gamma\gamma} >$ 200 GeV from $\ell^{+}\ell^{-}\gamma\gamma$ events and with $m_{\gamma\gamma} > $ 300 GeV from $\nu\bar{\nu}\gamma\gamma$ events are used to search for anomalous quartic gauge-boson couplings $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings.

Search for Anomalous Quartic ZZγγ Couplings in Photon-Photon Collisions

The self-couplings of the electroweak gauge bosons are completely specified by the non-Abelian gauge nature of the Standard Model (SM). The direct study of these couplings provides a significant opportunity to test the validity of the SM and the existence of new physics beyond the SM up to the high energy scale. For this reason, we investigate the potential of the processes γγ→ZZ, e-γ→e-γ⁎γ→e-ZZ, and e+e-→e+γ⁎γ⁎e-→e+ZZe- to examine the anomalous quartic couplings of ZZγγ vertex at the Compact Linear Collider (CLIC) with center-of-mass energy 3 TeV. We calculate 95% confidence level sensitivities on the dimension-8 parameters with various values of the integrated luminosity. We show that the best bounds on the anomalous fM2/Λ4, fM3/Λ4, fT0/Λ4, and fT9/Λ4 couplings arising from γγ→ZZ process among those three processes at center-of-mass energy of 3 TeV and integrated luminosity of Lint=2000 fb−1 are found to be [-3.30;3.30]×10-3 TeV−4, [-1.20;1.20]×10-2 TeV−4, [-3.40;3.40]×10-3 TeV−4, and [-1.80;1.80]×10-3 TeV−4, respectively.