Finding better ways to prove the Standard Model Effective Field Theory is a very important direction of research. This paper focuses on measurements of Electroweak triple gauge couplings, paying special attention on the regime of validity of the Effective Field Theory (EFT). In this regard, one of our goals is to find measurements leading to a large increase of the interference between the SM amplitude and the contribution of irrelevant operators in the EFT. We propose two such distributions that will lead to a better accuracy. Improvements compared to the traditional methods as well as LHC high luminosity prospects are discussed.
This article reviews some recent developments in the analysis of anomalous triple and quartic vector boson couplings that have been discussed at the UK Phenomenology Workshop on Collider Physics 1999 in Durham.
We examine the potential of pp-> p gamma p -> p W q X reaction to probe anomalous WWgamma couplings at the LHC. We find 95% confidence level bounds on the anomalous coupling parameters with various values of the integrated luminosity. We show that the reaction pp -> p gamma p -> p W q X at the LHC highly improve the current limits.
We present some physics topics that can be studied at the LHC using proton tagging. We distinguish the QCD (Pomeron structure, BFKL analysis...) from the exploratory physics topics (HIggs boson, anomalous couplings between photons and $W/Z$ bosons
We study the possibility for the process $pp \rightarrow pγp \rightarrow pW^-t(W^+\bar t)X$ with anomalous Wtb couplings in a model independent effective Lagrangian approach at the LHC. We find 95% confidence level bounds on the anomalous coupling parameters for various values of the integrated luminosity. The improved constraints on the anomalous Wtb couplings have been obtained compared to current limits.
We study triple-parton scattering effects in open charm production in proton-proton collisions at the LHC. Predictions for one, two and three $c\bar c$ pairs production are given for $\sqrt{s}= 7$ TeV and $\sqrt{s}= 13$ TeV. Quite large cross sections, of the order of milibarns, for the triple-parton scattering mechanism are obtained. We suggest a measurement of three $D^{0}$ or three $\bar{D^{0}}$ mesons by the LHCb collaboration. The predicted visible cross sections are of the order of a few nanobarns. The counting rates including $D^{0} \to K^{-}π^{+}$ branching fractions are also given. We…
We describe a simple extension of the standard model, containing a scalar singlet and a triplet fermion. The model can explain the possible enhancement in the decay $H \rightarrow γγ$ at the LHC together with the excess found in the Higgs boson search at LEP2. The structure of the model is motivated by a recent argument, that was used to explain the number of fermion generations. For the sake of completenes we also considered the contributions from higher multiplets.
We calculate the spinor helicity amplitudes of anomalous $H\to ZZ \to 4\ell$ decay. After embedding these analytic formulas into the $\texttt{MCFM}$ package, we study the interference effects between the anomalous $gg\to H\to ZZ \to 4\ell$ process and the SM processes, which are indispensable in the Higgs off-shell region. Subsequently, the constraints on the anomalous couplings are estimated using LHC experimental data.
We report on a possible measurement at the LHC using the first data and a luminosity of 10 pb$^{-1}$ of $W$ and $Z$ pair production via two-photon exchange. This measurement allows to increase the present sensitivity on $WWγγ$ and $ZZγγ$ quartic anomalous couplings from the LEP experiments by almost three orders of magnitude.
We investigate the constraints on the anomalous quartic $ZZγγ$ couplings through the process $p p\to pγp\to p γq Z X$ 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 $10^{-6}GeV^{-2}$ which are about four orders of magnitude more restricted with respect to current experimental bounds.
We investigate the anomalous interactions of heavy up-type quark t' in a $γγ$ collision at the LHC. We have obtained 95% confidence level(CL)limit of $t'q γ$ anomalous coupling by taking into account three forward detector acceptances: $0.0015<ξ<0.15$,$0.0015<ξ<0.5$, and $0.1<ξ<0.5$.
We study the T odd correlations induced by CP violating anomalous top-quark couplings at both production and decay level in the process gg --> t t_bar --> (b mu+ nu_mu) (b_bar mu- nu_mu_bar). We consider several counting asymmetries at the parton level and find the ones with the most sensitivity to each of these anomalous couplings at the LHC.
In some extensions of the Standard Model, Yukawa couplings of the physical Higgs boson can be deviated from those in the Standard Model. We study a possibility whether or not such anomalous Yukawa couplings are consistent with the LHC Run 1 data. It is found that sizable deviations of top and bottom (and tau) Yukawa couplings from the Standard Model predictions can nicely fit the data. New physics beyond the Standard Model can be revealed through more precise measurements of such anomalous Yukawa couplings at the LHC Run 2 in the near future. We also discuss a simple setup which can leads to a…
We compare vector boson fusion and quark antiquark annihilation production of vector boson pairs at the LHC and include the effects of anomalous couplings. Results are given for confidence intervals for anomalous couplings at the LHC assuming that measurements will be in agreement with the standard model. We consider all couplings of the general triple vector boson vertex and their correlations. In addition we consider a gauge invariant dimension-six extension of the standard model. Analytical results for the cross sections for quark antiquark annihilation and vector boson fusion with anomalou…
The single production of top quark due to flavor changing neutral current (FCNC) interaction and its decay to bW are studied at CLIC+LHC based gamma-p colliders. We consider both t-c-gamma and t-u-gamma anomalous couplings. The anomalous charm (up) quark anomalous coupling parameter kappa_gamma^c (kappa_gamma^u) can be probed down to 9.5x10^-3 (8.0x10^-3) at a gamma-p collider with sqrt{s_ep}=6.48 TeV and L_int=100 fb^-1.
We investigate the sensitivity of the heavy ion mode of the LHC to anomalous Higgs boson couplings to photons, H-photon-photon, through the analysis of the processes photon photon to b anti-b and photon photon to photon photon in peripheral heavy ion collisions. We suggest cuts to improve the signal over background ratio and determine the capability of LHC to impose bounds on anomalous couplings by searching for a Higgs boson signal in these modes.
In a topcolor-assisted technicolor model (TC2) with large FCNC top quark couplings, we study its correlated contributions to the top quark forward-backward asymmetry ($A_{FB}$) at the Tevatron, the top charge asymmetry ($A_{C}$) and the triple-top production at the LHC. Under current constraints on the top quark from the LHC and Tevatron(such as the total and differential production rates), we scan the parameter space of such a TC2 model. We find that in the allowed parameter space the TC2 model can explain the Tevatron measured $A_{FB}$ at $2σ$ level, but meanwhile significantly enhance $A_{C…
We show how the $W$ boson polarization in the process of associated $W^{\pm}H$ production at the Large Hadron Collider (LHC) can be used to constrain anomalous $WWH$ couplings. We first calculate the spin density matrix for the $W$ to linear order in the anomalous couplings, which are assumed to be small. We then evaluate angular asymmetries in the decay distributions of leptons produced in the decay of the $W$ and show how they can be used to measure the individual elements of the polarization tensor. We estimate the limits that can be placed on the anomalous $WWH$ couplings at a future run o…
We present a new method to test the Standard Model expectations at the LHC using photon-induced $WW$ production. Both $W$ decay in the main ATLAS or CMS detectors while scattered protons are measured in forward detectors. The sensitivity to anomalous $WWγ$ triple gauge coupling can be improved by more than a factor 5 or 30 compared to the present LEP or Tevatron sensitivity respectively.
We study possibilities to measure the triple anomalous W-boson couplings to photon in the $eγ\to Wν$ process via its lepton decay channel (with the simplest signature). We found that in the study of the $W$ quadruple momentum $λ$ one can limit himself within a small region in phase space. A way to find this region is proposed. The obtained estimates for $λ$ at TESLA project are roughly twice better than anticipated for $e+e-$ mode. For $W$ anomalous magnetic momentum the discussed mode gives no improvements as compared $e+e-$ mode.
We have examined $HZγ$ vertex to obtain the limits on anomalous $a_γ$, $b_γ$ and $\tilde b_γ$ couplings in a model independent way through the $γp$ collisions via the process $pp\to p γp\to pHqX$. The sensitivities to the anomalous couplings can be obtained as $|b_γ|$, $|\tilde{b}_γ|\sim 10^{-3}$ for the integrated luminosity of $L_{int}=100 ~\mathrm{fb}^{-1}$ at the LHC with $\sqrt{s}=14$ TeV.
We first report on possible measurements at the LHC using the first data and a luminosity of 10 pb$^{-1}$ of $W$ and $Z$ pair production via two-photon exchange. This measurement allows in particular to increase the present sensitivity on $WWγγ$ and $ZZγγ$ quartic anomalous couplings from the LEP experiments by almost three orders of magnitude. We also discuss the possible improvements on quartic and trilinear anomalous couplings at high luminosity at the LHC using new forward proton taggers to be installed at 220 and 420 m from the CMS or ATLAS detectors.
We show how one can measure anomalous WWZ- and WWgamma-couplings with minimal statistical error using integrated observables, without having to assume that the anomalous couplings are small. We propose a parametrisation of these couplings which is well suited for the extraction of both single and many parameters, and which leads to a very simple form of the integrated cross section, from which additional information on the couplings can be obtained.
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.
We estimate model-independent bounds that could be obtained on the anomalous $ZZH$ vertex using polarization parameters of the $Z$ boson produced in the Higgstrahlung process at the LHC. We calculate the eight independent polarization parameters from the spin density matrix elements of the $Z$, which can probe underlying new physics contributions to $ZH$ production. By using the approach that connects these polarization observables to the coefficients in the angular distribution of the decay products of the $Z$, we estimate the limits on the anomalous $ZZH$ coupling that can be obtained at the…
The measurement of the triple-differential dijet production cross section as a function of the average transverse momentum $p_{T,\textrm{avg}}$, half the rapidity separation $y^{*}$, and the boost $y_{b}$ of the two leading jets in the event enables a kinematical scan of the underlying parton momentum distributions. We compute for the first time the second-order perturbative QCD corrections to this triple-differential dijet cross section, at leading color in all partonic channels, thereby enabling precision studies with LHC dijet data. A detailed comparison with experimental CMS 8 TeV data is …
We have examined the constraints on the anomalous $tqγ$ ($q=u,c$) couplings through the process $pp\to pγp\to pWbX$ at the LHC by considering three forward detector acceptances: $0.0015< ξ< 0.5$, $0.0015< ξ<0.15$ and $0.1< ξ< 0.5$. The sensitivity bounds on the anomalous couplings have been obtained at the $95%$ confidence level in a model independent effective lagrangian approach. We have found that the bounds on these couplings can be highly improved compared to current experimental bounds.
We study the dimension-6 quark anomalous electroweak couplings in the formulation of linearly realized effective Lagrangian. We investigate the constraints on these anomalous couplings from the $pp \rightarrow W^+W^-$ process in detail at the LHC. With additional kinematic cuts, we find that the 14 TeV LHC can provide a test of anomalous couplings of $O(0.1-1)\,{\rm TeV}^{-2}$. The $pp \rightarrow ZZ/Zγ/γγ$ processes can provide a good complement as they are sensitive to those anomalous couplings which do not affect the $pp \rightarrow W^+W^-$ process. Those processes that only contain anomalo…
We make a careful analysis of $W^\pmγ$ production at the LHC, identifying the $W^\pm$ through leptonic decays, with a view to exploring the sensitivity of the machine to anomalous $CP$-conserving $WWγ$ interactions. All the available kinematic variables are used, but we find that the most useful one is the opening angle in the transverse plane between the decay products of the $W^\pm$. It is shown that even a simple-minded analysis using this variable can lead to a much greater sensitivity at the LHC than the current constraints on the relevant parameters.
The installation of forward proton detectors at the LHC will provide the possibility to perform new high-precision measurements, opening a novel window on physics beyond the Standard Model. We review recent simulations and theoretical developments about the measurement of anomalous light-by-light scattering. The search for this process is expected to provide bounds on a wide range of new particles. Future perspectives for precision QED at the LHC are also briefly discussed.
We have investigated the flavor changing top quark physics on the dimension-six anomalous $tqγ$ ($q=u,c$) couplings through the process $pp\to pγγp\to p t\bar{q}p$ at the LHC by considering different forward detector acceptances. In this paper, we have taken into account and examine the effects of top quark decay. The sensitivity bounds on the anomalous couplings and, $t\to qγ$ branching ratio have been obtained at the $95\%$ confidence level for the effective lagrangian approach. Besides, we have investigated the effect of the anomalous couplings on single top quark spin asymmetry.
We present leading-order (LO) cross sections for the production of three top quarks ($tt\tb$,$t\tb\tb$) at the Large Hadron Collider (LHC). We find a total LO cross section for triple-top production in the Standard Model of $σ\approx 2 $ fb at $\sqrt{s}=14$ TeV and we give examples of two new physics models which have a significant enhancement to this channel. In the Minimal Supersymmetric Standard Model (MSSM), there are regions of parameter space where the decays of gluino pairs into final states including three tops has a cross section $σ\approx 41$ fb. In a leptophobic $Z'$ model featuring…
We perform an exclusive study of the anomalous $Wtb$ interaction in the context of LHC. The limits on $Wtb$ anomalous couplings have been estimated via the measurements of the top-quark decay width and cross-section as well as production asymmetries in case the CP is violated. Our investigations reveal that the upper bounds on $(|C_L|, |C_R|)$ would be of about (1.82, 0.03) $\times 10^{-4}$ at $2.5 σ$ C.L., for the already collected data at the LHC with $\sqrt{S} = 13$ TeV for an integrated luminosity of 139 fb$^{-1}$. The corresponding limits for future hadron colliders, namely, High Luminosi…
Diboson production processes are of great importance in high-energy physics and a precise theoretical knowledge of VV production is mandatory not only in view of precision tests of the Standard Model but also in the one of new physics searches. We present results of arXiv:1804.01477, where we computed the NLO QCD and NLO electroweak corrections to diboson production processes at the LHC including the effect of the anomalous triple-gauge-boson interactions at NLO QCD accuracy. The anomalous triple-gauge-boson interactions are parametrized in terms of higher-dimensional operators in the effectiv…
In this study, we investigate the potential of the process $pp\rightarrow pγ^{*} p\rightarrow p τ\barν_τq^{\prime} X$ 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 $a_τ$ and $\vert$$d_τ$$\vert$ compared to the current experimental sensitivity bounds. The $γp$ mode of photon reactions a…
The potential of ep collision to prospect for anomalous Wtb vertex is discussed from the single top quark production process $ep\to t\barν+X$ for TESLA+HERAp and CLIC+LHC energies. Sensitivities to anomalous couplings $F_{2L}$ and $F_{2R}$, in the case of CLIC+LHC, are shown to be comparable with LHC.
The forward proton detectors recently installed and operating at the LHC open the possibility to observe photon collisions with high precision, providing a novel window on physics beyond the Standard Model. We review recent simulations and theoretical developments about the measurement of anomalous $γγγγ$ and $Zγγγ$ interactions. The searches for these anomalous gauge interactions are expected to set bounds on a wide range of particles including generic electroweak particles, neutral particles with dimension-5 coupling to gauge bosons, polarizable dark particles, and are typically complementar…
In these proceedings I explore one aspect of gauge-boson physics at the LHC - Triple Gauge-boson Couplings (TGCs) in $WZ$ and Wgamma production. Methods for extracting confidence limits on anomalous TGCs are assessed, while accounting for the effects of higher order QCD corrections and contributions from other theoretical and detector related systematics. Detector response has been parametrised according to the ATLAS detector's specifications. A strategy for reporting the anomalous coupling limits is introduced which removes the ambiguities of form factors by reporting the limits as a function…
Very recently, the CMS collaboration has reported a search for the production for a Standard Model (SM) Higgs boson in association with a top quark pair ($t bar{t} H$) at the LHC Run-2 and a best fit $t bar{t} H$ yield of $1.5 pm 0.5$ times the SM prediction with an observed significance of $3.3 sigma$. We study a possibility of whether or not this observed deviation can be explained by anomalous Higgs Yukawa couplings with the top and the bottom quarks, along with the LHC Run-1 data for the Higgs boson properties. We find that anomalous top and bottom Yukawa couplings with about $0-20$% and $…
In the absence of a concrete discovery of new physics at the LHC, global analyses of the standard model effective field theory (SMEFT) are important to find and describe the impact of new physics beyond the energy reach of the LHC. Among the SMEFT operators that can be constrained via various measurements, the dimension six triple gluon operator involves neither the Higgs boson nor the top quark, yet its variation can have measurable effects on top and Higgs production. Without independent constraints on its impact, the sensitivity of measurements in the top and Higgs sectors to new physics is…
We analyze the anomalous quartic gauge boson couplings $WWγγ$ and $ZZγγ$, described by dimension-6 effective quartic Lagrangian at the LHC. The sensitivities to anomalous quartic gauge couplings $a_{0,c}^{W,Z}/Λ^2$ by examining the two different photon-induced processes $pp\to pγp\to p WγqX$ and $pp\to pγp\to p ZZ qX$ with $W$ and $Z$s decaying leptonically are investigated. We show that $γp$ mode of photon-induced reactions at the LHC are able to probe these couplings to the order of $10^{-6}$-$10^{-7}$ GeV$^{-2}$ at 95 % confidence level with $\sqrt s$ = 14 TeV and for proton-proton luminosi…
Possible anomalous single productions of the fourth standard model generation up and down type quarks at CERN Large Hadron Collider are studied. Namely, $p p \to u_4 (d_4) X$ with subsequent $u_4\to bW^{+}$ process followed by leptonic decay of $W$ boson and $d_4\to bγ$ (and its h.c.) decay channel are considered. Signatures of these processes and corresponding standard model backgrounds are discussed in detail. Discovery limits for quark mass and achievable values of anomalous coupling strength are determined.
Deviations from SM expectations in the Higgs sector can be parameterized by an effective Lagrangian. The corresponding anomalous couplings have been implemented in a Monte Carlo program for Higgs production in vector boson fusion, at NLO QCD accuracy. It allows to study anomalous coupling effects for production and decay of the Higgs boson. We analyze deviations allowed by LEP data and study a new azimuthal angle variable which directly measures the interference between CP-even, CP-odd and SM couplings.
We consider direct bounds on the coefficients of higher dimensional top quark dipole operators from their contributions to anomalous top couplings that affect some related processes at the LHC. Several observables are studied. In particular, we incorporate for the first time in this type of analysis the recently measured associated $t \bar{t} V$ production, which is currently the only measured direct observable sensitive to the dipole operator involving the hypercharge field. We perform a Bayesian analysis to derive the $1(2)σ$ confidence level (CL) intervals on these coefficients.
We derive bounds on Higgs and gauge--boson anomalous interactions using the CDF data for the process $p \bar{p} \to γγγ+ X$. We use a linearly realized $SU_L(2) \times U_Y(1)$ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, keeping the fermionic couplings unchanged. All dimension--six operators that lead to anomalous Higgs interactions involving $γ$ and $Z$ are considered. We also show the sensitivity that can be achieved for these couplings at Fermilab Tevatron upgrades.
Low energy (1-loop) constraints on anomalous triple gauge boson vertices (TGV's) are revisited and compared to the sensitivity achievable at LEP II and at future linear $e^+e^-$ colliders. The analysis is performed within the framework of an effective Lagrangian of gauge invariant dimension six operators with the gauge bosons and a single Higgs doublet field as the low energy degrees of freedom. The low energy data do not directly bound TGV's but they provide strong constraints on models which lead to anomalous gauge boson interactions in addition to other low energy effects.
Many new physics models beyond the standard model ($SM$) can give rise to the large anomalous top couplings $tqg$ ($q=u$ and $c$). We focus our attention on these couplings induced by the topcolor-assisted technicolor ($TC2$) model and the littlest Higgs model with $T$-parity (called $LHT $ model), and consider their contributions to the production cross section and the charge asymmetry for $tW$ production at the $LHC$. We find that the anomalous top coupling $tqg$ induced by these two kinds of new physics models can indeed generate sizable charge asymmetry. The correction effects of the $LHT …
The determination of the electromagnetic dipole moments of the top quark is one of the most important goals of the top quark physics program in the collider experiments. For this reason, the top quark pair production to investigate the sensitivity on the electric and magnetic dipole moments of the top quark via the process $pp\rightarrow p γp \rightarrow p t \bar{t} X$ at the Large Hadron Collider (LHC), the High-Luminosity Large Hadron Collider (HL-LHC) and High-Energy Large Hadron Collider (HE-LHC) is discussed. We apply pure leptonic and semileptonic decays for top quark pair production in …
We study the process pp->QVX (where Q=t,b and V=g,gamma,Z) through the anomalous interactions of the new heavy quarks at the LHC. Considering the present limits on the masses and mixings, the signatures of the heavy quark anomalous interactions are discussed and analysed at the LHC for the center of mass energy of 13 TeV. An important sensitivity to anomalous couplings kappa_{g}^{t'}/Lambda=0.10 TeV^{-1}, kappa_γ^{t'}/Lambda=0.14 TeV^{-1}, kappa_{Z}^{t'}/Lambda=0.19 TeV^{-1} and kappa_{g}^{b'}/Lambda=0.15 TeV^{-1}, kappa_{Z}^{b'}/Lambda=0.19 TeV$^{-1}, kappa_γ^{b'}/Lambda=0.30 TeV$^{-1} for th…
In this manuscript, we study the LHC signatures of a non-standard heavy neutral Higgs boson H at the 14 TeV LHC model-independently by taking the anomalous HVV coupling constants in the possible range obtained in our previous paper, Ref.[1]. We suggest WW scattering and VH associated production as two sensitive processes for detecting H, and the latter is more sensitive than the former. The study is at the hadron level with signals and backgrounds carefully calculated. Certain kinematic cuts are proposed to suppress the backgrounds effectively. We take several values of the heavy Higgs masses …
The currently unmeasured triple Higgs coupling is one of the strong motivations for future physics programs at the LHC and beyond. A sufficiently precise measurement can lead to qualitative changes in our understanding of electroweak symmetry breaking and the cosmological history of the Higgs potential. As such, the quantitative measurement of this coupling is now one of the benchmark measurements for any proposed collider. We study the capability of a potential $27\,\mathrm{TeV}$ HE-LHC upgrade in measuring the Higgs trilinear coupling via the di-Higgs production process in the $b\bar{b}γγ$ c…
Higher-dimensional multi-gluon interactions affect essentially all effective Lagrangian analyses at the LHC. We show that, contrary to common lore, such operators are best constrained in multi-jet production. Our limit on the corresponding new physics scale in the multi-TeV range exceeds the typical reach of global dimension-6 Higgs and top analyses. This implies that the pure Yang-Mills operator can safely be neglected in almost all specific higher-dimensional analyses at Run II.
The anomalous neutral triple gauge boson couplings (aNTGCs) for the Z gamma gamma and Z gamma Z vertices described by dimension-eight operators are examined through the process pp to l^{+}l^{-} gamma at the High-Luminosity Large Hadron Collider (HL-LHC). We performed an analysis on transverse momentum of photon and angular distribution of charged lepton in the final state including detector effects. Sensitivity limits of the C_{\widetilde{B}W}, C_{BB} couplings are obtained at 95 % C.L. to constrain for the range [-1.88: 1.88] TeV^{-4}, [-1.47: 1.47] TeV^{-4} and [-1.14:1.14] TeV^{-4}, [-0.86:…
We present a calculation of the next-to-leading-order QCD and electroweak corrections to WWW production with leptonically decaying $\mathrm{W}$ bosons at the LHC, fully taking into account off-shell contributions, intermediary resonances, and spin correlations. The contributions of the quark-antiquark-induced electroweak correction to typical fiducial cross sections at the LHC are of the order of 5-8% and grow to tens of percent in the high-energy tails of distributions. We observe strong cancellations among the positive quark-photon and negative quark-antiquark-induced electroweak corrections…
The capability of the LHC to study the electromagnetic dipole moments of the top quark is discussed. In particular, the process $pp\to pγγp\to pt\bar{t}p$, which is supposed to be tagged by the forward/backward detectors at the LHC experiments, is used to explore the top quark electric and magnetic moments. We perform analytical calculations and then a numerical analysis on the sensitivity of the total cross section of the top quark pair production in $γγ$ scattering at the LHC to the anomalous top quark couplings with photon. It is shown that improvements in the bounds on the electromagnetic …
At a high energy $ep$ collider, such as the Large Hadron-Electron Collider (LHeC) which is being planned at CERN, one can access the $WWγ$ vertex exclusively in charged current events with a radiated photon, with no interference from the $WWZ$ vertex. We find that the azimuthal angle between the jet and the missing momentum in each charged current event is a sensitive probe of anomalous $WWγ$ couplings, and show that for quite reasonable values of integrated luminosity, the LHeC can extend the discovery reach for these couplings beyond all present experimental bounds.
The $WW$ production is the primary channel to directly probe the triple gauge couplings. We first analyze the $e^+ e^- \rightarrow W^+ W^-$ process at the future lepton collider, China's proposed Circular Electron-Positron Collider (CEPC). We use the five kinematical angles in this process to constrain the anomalous triple gauge couplings and relevant dimension six operators at the CEPC up to the order of magnitude of $10^{-4}$. The most sensible information is obtained from the distributions of the production scattering angle and the decay azimuthal angles. We also estimate constraints at the…
We consider the production of a single top quark in association with a Higgs boson at the LHC. In particular, we compute the cross sections for the processes $ p p \to t h j$, $t h b$, $t h W$, $t h j j$, $t h j b$, $t h W j$, $t h W b$ in the presence of the anomalous $Wtb, WWh$ and $tth$ couplings. We find that the anomalous $Wtb$ and $tth$ couplings can enhance the cross sections significantly. We also analyze a few signatures and show that, if these couplings are indeed anomalous, then with enough data, one should be able to observe the production of the Higgs boson in association with sin…
The recent discovery of the $\sim 125$ GeV Higgs boson by Atlas and CMS experiments has set strong constraints on parameter space of the minimal supersymmetric model (MSSM). However these constraints can be weakened by enlarging the Higgs sector by adding a triplet chiral superfield. In particular, we focus on the $Y=0$ triplet extension of MSSM, known as TESSM, where the electroweak contributions to the lightest Higgs mass are also important and comparable with the strong contributions. We discuss this in the context of the observed Higgs like particle around 125 GeV and also look into the st…
We investigate the prospects for discovering the Flavour Changing Neutral Current (FCNC) $tqZ$ couplings via two production processes yielding trilepton signals: top quark pair production $pp\to t\bar{t}$ with one top decaying to the $Z$ boson and one light jet and the anomalous single top plus $Z$ boson production process $pp\to tZ$. We study these channels at various successors of the Large Hadron Collider~(LHC), i.e., the approved High-Luminosity LHC (HL-LHC) as well as the proposed High-Energy LHC~(HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh). We perform a full simul…
