Anomalous Coupling Parameters Research Articles

Search for high-mass exclusive diphoton production with tagged protons in proton-proton collisions at s=13 TeV

A search is presented for high-mass exclusive diphoton production via photon-photon fusion in proton-proton collisions at s=13 TeV in events where both protons survive the interaction. The analysis utilizes data corresponding to an integrated luminosity of 103 fb−1 collected in 2016–2018 with the central CMS detector and the CMS and TOTEM precision proton spectrometer (PPS). Events that have two photons with high transverse momenta (pTγ>100 GeV), back-to-back in azimuth, and with a large diphoton invariant mass (mγγ>350 GeV) are selected. To remove the dominant inclusive diphoton backgrounds, the kinematic properties of the protons detected in PPS are required to match those of the central diphoton system. Only events having opposite-side forward protons detected with a fractional momentum loss between 0.035 and 0.15 (0.18) for the detectors on the negative (positive) side of CMS are considered. One exclusive diphoton candidate is observed for an expected background of 1.1 events. Limits at 95% confidence level are derived for the four-photon anomalous coupling parameters |ζ1|<0.073 TeV−4 and |ζ2|<0.15 TeV−4, using an effective field theory. Additionally, upper limits are placed on the production of axionlike particles with coupling strength to photons f−1 that varies from 0.03 TeV−1 to 1 TeV−1 over the mass range from 500 to 2000 GeV. © 2024 CERN, for the CMS and TOTEMs Collaboration 2024 CERN

Probing the Anomalous tqgamma Couplings in Photon-Proton Collisions

The top quark flavor changing neutral current processes are extremely suppressed within the Standard Model. Nevertheless, they could be enhanced in a new physics model beyond the Standard Model. Investigating the top quark’s flavor changing neutral current interactions at colliders would be an important test in terms of new physics. In this work, we examine the potentials of the processes \({e^{-}} {p} {\rightarrow } {e^{-}} {\gamma } {p} {\rightarrow } {e^{-}} W^{+} b {\gamma }{\rightarrow } {e^{-}} {j} {\bar {j}} b {\gamma }\) and \({e^{-}} {p} {\rightarrow } {e^{-}} {\gamma } {p} {\rightarrow } {e^{-}} W^{+} b {\gamma }{\rightarrow } {e^{-}} \textit {l} {\nu }_{\textit {l}} b {\gamma }\) at the FCC-eh with \(\sqrt {s}=7.08\) and 10.0 TeV to study anomalous tqγ couplings via effective Lagrangians. We obtain 95% confidence level sensitivities on the anomalous coupling parameters at the two FCC-eh energies and various integrated luminosities. We find that our limits are at least two orders of magnitude better than the current LHC experimental results.

First Search for Exclusive Diphoton Production at High Mass with Tagged Protons in Proton-Proton Collisions at sqrt[s]=13 TeV.

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp→pγγp with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb^{-1} collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13TeV at the LHC. Events are selected with a diphoton invariant mass above 350GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons match the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% confidence level are |ζ_{1}|<2.9×10^{-13} GeV^{-4} and |ζ_{2}|<6.0×10^{-13} GeV^{-4}.

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.

Model-independent sensitivity estimates for the electromagnetic dipole moments of the top quark at the Large Hadron Collider and beyond

As the heaviest known fundamental particle, the top quark ensures testing of the Standard Model and occupies a significant role in a lot of theories of new physics beyond the Standard Model. Up to now, the top quark has been only generated at the Tevatron and the Large Hadron Collider. However, one of the most important tasks of the physics program at the Large Hadron Collider is the investigation of the anomalous top quark interactions. In addition, the production of single top quarks, though rarer than production in pairs, presents us a different way to study the top quark produced via the electroweak interaction. This makes single top quark production an important signature for studying the properties of the top quark. Hence, we examine the anomalous tt¯γ interactions to investigate limits on the anomalous aA and aV couplings through single top quark production of the process pp→pγ⁎p→ptWX at the Large Hadron Collider, the High Luminosity Large Hadron Collider and High Energy Large Hadron Collider. The best limits obtained on the anomalous aA and aV couplings through the subprocess γ⁎b→Wt at the High Energy Large Hadron Collider with Lint=15 ab−1 at 68% Confidence Level are found to be |aA|=0.0509 and aV=[−0.3171;0.0077]. Therefore, we understand that γ⁎p collisions at the High Energy Large Hadron Collider improves the sensitivity limits of the anomalous coupling parameters according to previous studies.

Search for anomalous triple gauge couplings in WW and WZ production in lepton + jet events in proton-proton collisions at sqrt{s} = 13 TeV

A search is presented for three additional operators that would lead to anomalous WWγ 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 eν 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 invariant mass, 95% confidence intervals are obtained for the anomalous coupling parameters of −1.58 < cWWW/Λ2< 1.59 TeV−2, −2.00 < cW/Λ2< 2.65 TeV−2, and −8.78 < cB/Λ2< 8.54 TeV−2, in agreement with standard model expectations of zero for each parameter. These are the strictest bounds on these parameters to date.

Search for the anomalous ZZH couplings at the CLIC

We have investigated the potential of Higgs boson production at [Formula: see text] mode of the Compact Linear Collider (CLIC) to probe anomalous ZZH couplings. Considering two different center of mass energies of CLIC ([Formula: see text] = 1.5 and 3 TeV) and various integrated luminosities, we have calculated 95% confidence level (CL) bounds on the anomalous ZZH coupling parameters [Formula: see text], [Formula: see text] and [Formula: see text]. We perform an analysis through the process [Formula: see text] with systematic uncertainties of [Formula: see text] = 0%, 5%, 10%. Obtained results have been discussed in terms of capability to probe anomalous ZZH couplings in the photoproduction process.

Analysis of the anomalous electromagnetic moments of the tau lepton in γp collisions at the LHC

In this study, we investigate the potential of the process pp→pγ⁎p→pτν¯τq′X at the LHC to examine the anomalous electromagnetic moments of the tau lepton. We obtain 95% confidence level bounds on the anomalous coupling parameters with various values of the integrated luminosity and center-of-mass energy. The improved bounds have been obtained on the anomalous coupling parameters of electric and magnetic moments of the tau lepton aτ and |dτ| compared to the current experimental sensitivity bounds. The γp mode of photon reactions at the LHC have shown that it has great potential for the electromagnetic dipole moments studies of the tau lepton.

Probing CP-violating WWγ couplings in γp collision at the LHC

We have studied the potential of [Formula: see text] collision at the Large Hadron Collider (LHC) to probe CP (Charge and Parity)-violating anomalous WW[Formula: see text] couplings via the process [Formula: see text]. Considering various integrated luminosities and forward detector acceptance values, we have obtained 95% confidence level (CL) bounds on the anomalous coupling parameters [Formula: see text] and [Formula: see text]. Obtained limits on the coupling parameters have been compared with the current limits.

Measurement of W±W± vector-boson scattering and limits on anomalous quartic gauge couplings with the ATLAS detector

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 $\mu$) 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 quartic gauge coupling parameters $\alpha_4$ and $\alpha_5$, is introduced, which allows more stringent limits on these parameters compared to the previous ATLAS measurement.

Search for anomalous electroweak production of WW/WZ in association with a high-mass dijet system in pp collisions at s=8 TeV with the ATLAS detector

A search is presented for anomalous quartic gauge boson couplings in vector-boson scattering. The data for the analysis correspond to $20.2$ fb$^{-1}$ of $\sqrt{s}=8$ TeV $pp$ collisions, and were collected in 2012 by the ATLAS experiment at the Large Hadron Collider. The search looks for the production of $WW$ or $WZ$ boson pairs accompanied by a high-mass dijet system, with one $W$ decaying leptonically, and a $W$ or $Z$ decaying hadronically. The hadronically decaying $W/Z$ is reconstructed as either two small-radius jets or one large-radius jet using jet substructure techniques. Constraints on the anomalous quartic gauge boson coupling parameters $\alpha_4$ and $\alpha_5$ are set by fitting the transverse mass of the diboson system, and the resulting 95% confidence intervals are $-0.024<\alpha_4<0.030$ and $-0.028<\alpha_5<0.033$.

Search for anomalous quartic WWZγ couplings at the future linear e+e− collider

In this paper, the potentials of two different processes [Formula: see text] and [Formula: see text] at the Compact Linear Collider (CLIC) are examined to probe the anomalous quartic [Formula: see text] gauge couplings. For [Formula: see text], 1.5 and 3[Formula: see text]TeV energies at the CLIC, 95% confidence level limits on the anomalous coupling parameters defining the dimension-six operators are found via the effective Lagrangian approach in a model independent way. The best limits on the anomalous couplings [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] which can be achieved with the integrated luminosity of [Formula: see text] at the CLIC with [Formula: see text] are [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively.

Anomalous quartic ZZγγ couplings at the CLIC

We study the sensitivity to anomalous quartic $ZZ\gamma\gamma$ couplings through the processes $e^{+}e^{-}\rightarrow Z\, Z\, \gamma$, $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} e^{-} \rightarrow e^{+} Z\, Z\, e^{-}$ and $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} \gamma^{*} e^{-} \rightarrow e^{+}\, Z\, Z\, e^{-}$ at the CLIC. We find $95\%$ confidence level bounds on these coupling parameters defining by the dimension-six operators. The best bounds on the anomalous $ZZ\gamma\gamma$ couplings among the three processes are obtained from $e^{+}e^{-}\rightarrow Z\, Z\, \gamma$ at a center of mass energy of $3$ TeV and an integrated luminosity of $590$ fb$^{-1}$. We show that the best bounds obtained on both the anomalous coupling parameters are of the order of $10^{-8}$ GeV$^{-2}$, significantly improving the current bounds.

Probe of anomalous quartic WWZγ couplings in photon-photon collisions

In this paper, we examine the potentials of the processes $\gamma \gamma\rightarrow W^{+} W^{-}Z $ and $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} \gamma^{*} e^{-} \rightarrow e^{+} W^{+} W^{-} Z e^{-}$ at the CLIC with $\sqrt{s}=0.5,1.5$ and $3$ TeV to investigate anomalous quartic $WWZ\gamma$ 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 $\gamma \gamma\rightarrow W^{+} W^{-}Z $ on the anomalous $\frac{k_{0}^{W}}{\Lambda^{2}}$, $\frac{k_{c}^{W}}{\Lambda^{2}}$ and $\frac{k_{2}^{m}}{\Lambda^{2}}$ couplings defined by CP-conserving effective Lagrangians are $[-1.73;\, 1.73]\times 10^{-7}$ GeV$^{-2}$, $[-2.44;\, 2.44]\times 10^{-7}$ and $[-1.89; \, 1.89]\times 10^{-7}$ GeV$^{-2}$, while $\frac{a_{n}}{\Lambda^{2}}$ coupling determined by CP-violating effective Lagrangians is obtained as $[-1.74;\, 1.74]\times 10^{-7}$ GeV$^{-2}$. In addition, the best limits derived on $\frac{k_{0}^{W}}{\Lambda^{2}}$, $\frac{k_{c}^{W}}{\Lambda^{2}}$ and $\frac{k_{2}^{m}}{\Lambda^{2}}$ and $\frac{a_{n}}{\Lambda^{2}}$ from the process $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} \gamma^{*} e^{-} \rightarrow e^{+} W^{+} W^{-} Z e^{-}$ are obtained as $[-1.09;\, 1.09]\times 10^{-6}$ GeV$^{-2}$, $[-1.54;\, 1.54]\times 10^{-6}$ GeV$^{-2}$, $[-1.18;\, 1.18]\times 10^{-6}$ and $[-1.04;\, 1.04]\times 10^{-6}$ GeV$^{-2}$, respectively.

Probing triple-W production and anomalous WWWW coupling at the CERN LHC and future O 100 $$ \mathcal{O}(100) $$ TeV proton-proton collider

Triple gauge boson production at the LHC can be used to test the robustness of the Standard Model and provide useful information for VBF di-boson scattering measurement. Especially, any derivations from SM prediction will indicate possible new physics. In this paper we present a detailed Monte Carlo study on measuring WWW production in pure leptonic and semileptonic decays, and probing anomalous quartic gauge WWWW couplings at the CERN LHC and future hadron collider, with parton shower and detector simulation effects taken into account. Apart from cut-based method, multivariate boosted decision tree method has been exploited for possible improvement. For the leptonic decay channel, our results show that at the sqrt{s}=8(14)[100] TeV pp collider with integrated luminosity of 20(100)[3000] fb-1, one can reach a significance of 0.4(1.2)[10]sigma to observe the SM WWW production. For the semileptonic decay channel, one can have 0.5(2)[14]sigma to observe the SM WWW production. We also give constraints on relevant Dim-8 anomalous WWWW coupling parameters.

Analysis of anomalous quartic WWZγ couplings in γp collision at the LHC

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→pγp→pWZqX to analyze anomalous quartic WWZγ couplings by two different, CP-violating and CP-conserving, effective Lagrangians at the LHC. We calculate 95% confidence level limits on the anomalous coupling parameters with various values of the integrated luminosity. Our numerical results show that the best limits obtained on the anomalous couplings k0WΛ2, kcWΛ2, k2mΛ2 and anΛ2 at s=14 TeV and an integrated luminosity of Lint=100 fb−1 are [−1.37;1.37]×10−6 GeV−2, [−1.88;1.88]×10−6 GeV−2, [−6.55;6.55]×10−7 GeV−2 and [−2.21;2.21]×10−6 GeV−2, respectively. Thus, γp mode of photon-induced reactions at the LHC highly improves the sensitivity limits of the anomalous coupling parameters k0WΛ2, kcWΛ2, k2mΛ2 and anΛ2.

Search for anomalous quarticWWγγcouplings in dielectron and missing energy final states inpp¯collisions ats=1.96 TeV

We present a search for anomalous components of the quartic gauge boson coupling WW{\gamma}{\gamma} 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 observed upper limits at 95 % C.L. are |a_0^W/Lambda^2|< 0.0025 GeV^-2 and |a_C^W/Lambda^2| < 0.0092 GeV^-2.

Probing W + W −γ production and anomalous quartic gauge boson couplings at the CERN LHC

Triple gauge boson associated production at the LHC serves as an interesting channel to test the robustness of the Standard Model. Any deviation from its SM prediction may indicate possible existence of relevant new physics, e.g., anomalous quartic gauge boson couplings. In this paper, a Monte-Carlo feasibility study of measuring WWA production with pure leptonic decays and probing anomalous quartic gauge-boson (e.g., WWAA) couplings, is presented in detail for the first time, with parton shower and detector simulation effects taken into account. Our results show that at the sqrt{s} = 14 TeV LHC with an integrated luminosity of 100 (30) fb-1, one can reach a significance of 9 (5) sigma to observe the SM WWA production, and can constrain at the 95% CL the anomalous WWAA coupling parameters, e.g., a_{0,c}^W/\Lambda^2 (see Ref.[15] for their definitions), at 10^{-5} GeV^{-2}, respectively.

Anomalous quarticZZγγcouplings inγpcollision at the LHC

We investigate the constraints on the anomalous quartic $ZZ\ensuremath{\gamma}\ensuremath{\gamma}$ couplings through the process $pp\ensuremath{\rightarrow}p\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\gamma}qZX$ at the LHC. Taking into consideration various forward detector acceptances and integrated LHC luminosities, we find 95% confidence level bounds on the anomalous coupling parameters. We show that the bounds on these couplings are at the order of ${10}^{\ensuremath{-}6}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}2}$ which are about four orders of magnitude more restricted with respect to current experimental bounds.

Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wγ production in [formula omitted] collisions at [formula omitted

We present searches for the anomalous γWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wγ, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6 fb−1 of integrated luminosity collected by the D0 detector in pp¯ collisions at 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 Δκγ, λ, and Δg1Z for a cutoff energy scale Λ=2 TeV. The combined 68% C.L. limits are −0.057<Δκγ<0.154, −0.015<λ<0.028, and −0.008<Δg1Z<0.054 for the LEP parameterization, and −0.007<Δκ<0.081 and −0.017<λ<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.