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: 0.86] TeV^{-4} with an integrated luminosity of 300 fb^{-1} and 3000 fb^{-1}, respectively.
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 discuss the prospects of searching for the neutral Higgs bosons of the triplet model in central exclusive production at the LHC. A detailed Monte Carlo analysis is presented for six benchmark scenarios for the Higgs boson, $H_1^{0}$, these cover $m_{H_1^0}=$~120, 150 GeV and doublet-triplet mixing of $c_H=$~0.2, 0.5 or 0.8. We find that, for appropriate values of $c_H$, an excellent Higgs mass measurement is possible for the neutral Higgs in the triplet model, and discuss how to distinguish the triplet model Higgs boson from the Higgs boson of the Standard Model.
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 $A_{C…
Finding better ways to prove the Standard Model Effective Field Theory is a very important direction of research. This paper focuses on measurements of Electroweak triple gauge couplings, paying special attention on the regime of validity of the Effective Field Theory (EFT). In this regard, one of our goals is to find measurements leading to a large increase of the interference between the SM amplitude and the contribution of irrelevant operators in the EFT. We propose two such distributions that will lead to a better accuracy. Improvements compared to the traditional methods as well as LHC hi…
It is well known that for the pure standard model triplet fermionic WIMP-type dark matter (DM), the relic density is satisfied around 2 TeV. For such a heavy mass particle, the production cross-section at 13 TeV run of LHC will be very small. Extending the model further with a singlet fermion and a triplet scalar, DM relic density can be satisfied for even much lower masses. The lower mass DM can be copiously produced at LHC and hence the model can be tested at collider. For the present model we have studied the multi jet ($\geq 2\,j$) + missing energy ($\cancel{E}_{T}$) signal and show that t…
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 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…
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…
Four independent dimension-eight operators give rise to anomalous neutral triple gauge boson interactions, one CP-even and three CP-odd. Only the CP-even operator interferes with the Standard Model for the production of a pair of on-shell neutral bosons. However, the effects are found to be tiny due mainly to the mismatch of the Z boson polarization between the productions from the SM and the new operator.
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…
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…
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 $WW$ 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…
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…
The effects of dimension-eight operators giving rise to anomalous neutral triple gauge boson interactions of $Zγγ$ and $ZγZ$ vertices in $pp\to l^-l^+γ$ and $pp\to ν\bar νγ$ are investigated at 100 TeV centre of mass energy of future circular hadron collider (FCC-hh). The transverse momentum of photon, invariant mass of $l^-l^+γ$ and angular distribution of charged lepton in the rest frame of $l^-l^+$ and Missing Energy Transverse (MET) are considered in the analysis. The realistic detector effects are also included with Delphes simulation. Sensitivity limits obtained at 95\% C.L. for $C_{\wid…
We investigate the charged Higgs boson signal at the LHC using its dominant production and decay modes with triple b-tagging, i.e. $tH^- \to t\bar tb \to b\bar bb W^+ W^-$, followed by leptonic decay of one W and hadronic decay of the other. We consider the continuum background from the associated production of $t\bar t$ with a b- or a light quark or gluon jet, which can be mis-tagged as b-jet. We reconstruct the top quark masses to identify the 3rd b-jet accompanying the $t\bar t$ pair, and use its p_T distribution to distinguish the signal from the background. Combining this with the reconst…
The See-Saw mechanism provides a nice way to explain why neutrino masses are so much lighter than their charged lepton partners. It also provides a nice way to explain baryon asymmetry in our universe via the leptogenesis mechanism. In this talk we review leptogenesis and LHC physics in a See-Saw model proposed in 1989, now termed the Type III See-Saw model. In this model, $SU(2)_L$ triplet leptons are introduced with the neutral particles of the triplets playing the role of See-Saw. The triplet leptons have charged partners with standard model gauge interactions resulting in many new features…
We study the prospects of probing large extra dimension model at the LHC through neutral triple gauge boson production processes. In theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the SM particles. We consider γγγ, γγZ, γZ Z and ZZZ production processes, and present our results for various kinematic distributions at the LHC for \sqrt{S}=14 TeV.
Differentiating Dimension-6 and Dimension-8 Effects in $ν$SMEFT at the HL-LHC
Institute of Physics（印度物理研究所）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；Institute for Particle Physics Phenomenology, Department of Physics, Durham University（达勒姆大学粒子物理现象学研究所）
We have analysed the production of WW and WZ vector-boson pairs at the LHC. These processes give rise to four-fermion final states, and are particularly sensitive to possible non-standard trilinear gauge-boson couplings. We have studied the interplay between the influence of these anomalous couplings and the effect of the complete logarithmic electroweak O(α) corrections. Radiative corrections to the Standard Model processes in double-pole approximation and non-standard terms due to trilinear couplings are implemented into a Monte Carlo program for p p -> 4f (+γ) with final states involving fo…
We clarify the role of vector boson fusion (VBF) in the production of heavy vector triplets at the LHC and the HL-LHC. We point out that the presence of VBF production leads to an unavoidable rate of Drell-Yan (DY) production and highlight the subtle interplay between the falling parton luminosities and the increasing importance of VBF production as the heavy vector mass increases. We discuss current LHC searches and HL-LHC projections in di-boson and di-lepton final states and demonstrate that VBF production outperforms DY production for resonance masses above 1 TeV in certain regions of the …
Several popular extensions of the Standard Model predict extra vector fields that transform as triplets under the gauge group SU(2)_L. These multiplets contain Z' and W' bosons, with masses and couplings related by gauge invariance. We review some model-independent results about these new vector bosons, with emphasis on di-lepton and lepton-plus-missing-energy signals at the LHC.
We investigate the implication of the recent discovery of a Higgs-like particle in the first phase of the LHC Run 1 on the Inert Higgs Doublet Model (IHDM). The determination of the Higgs couplings to SM particles and its intrinsic properties will get improved during the new LHC Run 2 starting this year. The new LHC Run 2 would also shade some light on the triple Higgs coupling. Such measurement is very important in order to establish the details of the electroweak symmetry breaking mechanism. Given the importance of the Higgs couplings both at the LHC and $e^+e^-$ Linear Collider machines, ac…
Nonperturbative effects in triple-differential dijet and Z+jet production at the LHC
II. Institute of Physics, Georg-August-Universität Göttingen（哥廷根大学第二物理研究所）；Institute of Experimental Particle Physics, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院实验粒子物理研究所）；Institute of Theoretical Physics, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院理论物理研究所）；Department of Physics, Panjab University（潘贾布大学物理系）
Measuring the triple Higgs coupling is a crucial task in the LHC and future collider experiments. We apply the Message Passing Neural Network (MPNN) to the study of the non-resonant Higgs pair production process $pp \to hh$ in the final state with $2b + 2\ell + E_{\rm T}^{\rm miss}$ at the LHC. Although the MPNN can improve the signal significance, it is still challenging to observe such a process at the LHC. We find that a $2σ$ upper bound (including a 10\% systematic uncertainty) on the production cross section of the Higgs pair is 3.7 times the predicted SM cross section at the LHC with the…
In this brief review we study the discovery potential of heavy Higgs induced single-top, same-sign top and triple-top quark productions at the Large Hadron Collider (LHC). The context is general two Higgs doublet model where such processes can be induced by additional Yukawa couplings and sub-Tev Higgs bosons. We show that these processes can be discovered at the ongoing or future high luminosity LHC run. Discovery of these multi-top productions may shed light on the mechanism behind baryogenesis or cosmic inflation.
In general, there can be mass differences among scalar bosons of the Higgs triplet field with the hypercharge of Y=1. In the Higgs triplet model, when the vacuum expectation value $v_Δ$ of the triplet field is much smaller than that $v$ ($\simeq 246$ GeV) of the Higgs doublet field as required by the electroweak precision data, a characteristic mass spectrum $ m_{H^{++}}^2-m_{H^+}^2\simeq m_{H^+}^2-m_{ϕ^0}^2(\equiv ξ)$ appears, where $m_{H^{++}}$, $m_{H^+}$, $m_{ϕ^0}$ are the masses of the doubly-charged ($H^{++}$), the singly-charged ($H^+$) and the neutral ($ϕ^0=H^0$ or $A^0$) scalar bosons,…
We present the results of a study of Higgs triplet boson production arising in the Littlest Higgs, Left-Right Symmetric, and Georgi-Machacek models in the W^\pm W^\pm, W^\pm Z, W^+ W^-, and Z Z channels at the LHC. We focus on the "gold-plated" purely leptonic decay modes and consider the irreducible electroweak, QCD, and t-quark backgrounds, applying a combination of forward-jet-tagging, central-jet-vetoing, and stringent leptonic cuts to suppress the backgrounds. We find that, given the constraints on the triplet vacuum expectation value (vev), considerable luminosity is required to observe …
We investigate a supersymmetric extension of the Minimal Supersymmetric Standard Model (MSSM), called the TNMSSM, containing a $SU(2)$ Higgs triplet $(\hat{T})$ of $Y=0$ hypercharge and a singlet superfields $(\hat{S})$ in the corresponding superpotential. The model can be viewed, equivalently, as an extension of the NMSSM with the addition of a $\hat{T}-\hat{S}$ interaction and of an extra coupling of the triplet to the two Higgs doublets of the NMSSM. In this scenario the Higgs particle spectrum at tree-level gets additional mass contributions from the triplet and singlet scalar components r…
The type-III see-saw model holding out a riveting rationale for the minuscule neutrino masses caters for a well-to-do phenomenology at the Large Hadron Collider (LHC). Several searches targetting the triplet fermions have been performed at the LHC. Not only are the signals for the leptonic final states considered in these searches suppressed by the branching fractions of the Standard Model (SM) bosons, but they are also beset with considerably large SM backgrounds. Thus, these searches are deemed not to be sensitive enough in probing the triplet fermions much heavier than 1 TeV. To this end, w…
ATLAS and CMS have discovered a Standard Model Higgs-like particle. One of the main discovery channels is the Higgs decay to two photons, which, at the moment, seems to be considerably enhanced over the Standard Model expectation. Models with additional charged matter coupling to the Higgs sector can enhance or decrease the Higgs to two photons branching ratio. We take this as motivation to confront the so-called Georgi-Machacek model of Higgs triplets with the results of recent searches for a SM Higgs boson performed at the LHC. We also investigate the model in regions of the allowed paramete…
Now that a Higgs boson has been discovered at the LHC, measuring its couplings to other particles is the next important step. In order to probe the electroweak symmetry breaking mechanism at its core it is crucial to reconstruct the scalar potential and hence measure the triple Higgs coupling at the LHC. We present a review of the main Standard Model Higgs boson pair production mechanisms in which the triple Higgs coupling plays a role and present the latest phenomenological analyses in view of a high luminosity LHC. One example of an analysis in the Two-Higgs-Doublet model will also be given …
After the discovery of a Higgs boson at the LHC, the next important step is to measure its couplings to fermions and bosons to unravel its true nature. In order to ultimately test the shape of the scalar potential that triggers the electroweak symmetry breaking, it is crucial to measure the triple Higgs coupling at the LHC. We then review the theoretical predictions of the main Standard Model Higgs pair production mechanisms that are needed for such a measurement and present the latest developments in the phenomenological analyses in view of a high luminosity LHC.
We investigate an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet. We focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV in the spectrum, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. The triplet extension gives rise to two additional charged Higgs bosons which do not couple to fermions but can decay into $Z W^\pm$. The presence of a very light pseudoscalar opens $a_1 W^\pm$ decay mode for the light charged …
An important task of the LHC is the investigation of the Higgs-boson sector. Of particular interest is the reconstruction of the Higgs potential, i.e. the measurement of the Higgs self-couplings. Based on previous analyses, within the 2HDMs type~I and~II, we analyze several two-dimensional benchmark planes that are over large parts in agreement with all theoretical and experimental constraints. For these planes we evaluate di-Higgs production cross sections at the (HL-)LHC with a center-of-mass energy of 13 TeV at NLO in the heavy top-quark limit with the code HPAIR. We investige in particular…
We investigate the scalar sector in an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet beside the $SU(2)$ scalar doublets. In particular, we focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. We analyze the exotic decay of the discovered Higgs $(h_{125})$ into two light (hidden) Higgs bosons present in the extension. The latter are allowed by the uncertainties i…
In this paper, triple neutral electroweak gauge boson production processes, viz. γγγ, γγZ, γZZ and ZZZ productions merged to 1-jet have been studied at the leading order in QCD in the context of Randall-Sundrum model at the LHC with center of mass energy \sqrt{S}=13 TeV. Decay of Z bosons into lepton-pairs has been considered. We present a selection of kinematical distributions matched to parton shower and show their deviation from the SM results as a result of the RS model. The uncertainties as a result of the factorization and renormalization scales are also presented.
In extended Higgs sectors that exhibit alignment without decoupling, the additional scalars are allowed to have large couplings to the Standard Model Higgs. We show that current nonresonant di-Higgs searches can be straightforwardly adapted to look for additional Higgses in these scenarios, where pair production of non-SM Higgses can be enhanced. For concreteness, we study pair production of exotic Higgses in the context of an almost inert two Higgs doublet model, where alignment is explained through an approximate $\mathbb{Z}_2$ symmetry under which the additional scalars are odd. In this con…
We propose an extension of the SUSY SU(5) which predicts LHC testable type-III seesaw. The supersymmetric SU(5) GUT model is extended by adding a 24-plet matter superfield along with a pair of $10_H$-plet and $\bar{10}_H$-plet Higgs superfields. The 24-plet carries a triplet and a singlet fermion multiplet of SU(2)$_L$, which leads to type I+III seesaw. The additional $10_H$ (and $\bar{10}_H$) multiplets help in achieving gauge coupling unification while keeping the triplet fermion mass in the TeV range, making them accessible at LHC. We study the phenomenology of this model in detail. Large l…
We investigate whether the triple-parton scattering effects can be observed in open charm production in proton-proton collisions at the LHC. We use so-called factorized Ansatz for calculations of hard multiple-parton interactions. The numerical results for each parton interaction are obtained within the $k_{T}$-factorization approach. 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…
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 …
We examine the Higgs triple coupling in MSSM and NMSSM under current constraints, which include the LHC measurements, Higgs data, B physics, electroweak precision observables, relic density and so on. The ratio $λ^{\rm MSSM}_{hhh}/λ^{\rm SM}_{hhh}$ is above 0.97, due to the highly constrained parameter space. While the ratio $λ^{\rm NMSSM}_{hhh}/λ^{\rm SM}_{hhh}$ can reach 0.1 under current constraints. The precise measurement in future collider will give a tighter constraint to the Higgs triple coupling in MSSM and NMSSM.
We studied the extension of Standard Model (SM) Higgs sector with $SU(2)$ triplet and SM gauge singlet in the context of supersymmetry. For a $Z_3$ symmetric superpotential where the singlet field generates the bi-linear Higgs mixing term between two Higgs doublets dynamically. Models like this often have a very light pseudoscalar as pseudo-Nambu Goldstone model of an extra $U(1)$ symmetry. We investigate the possibility of such light hidden Higgs boson with the data of the discovered Higgs boson around 125 GeV. Along with the neutral sector, the charged Higgs bosons in the triplet extended ca…
We consider non-abelian kinetic mixing between the Standard Model SU(2$)_L$ and a dark sector U(1$)^\prime$ gauge group associated with the presence of a scalar SU(2$)_L$ triplet. The magnitude of the resulting dark photon coupling $ε$ is determined by the ratio of the triplet vacuum expectation value, constrained to by $\lsim 4$ GeV by electroweak precision tests, to the scale $Λ$ of the effective theory. The corresponding effective operator Wilson coefficient can be $\mathcal{O}(1)$ while accommodating null results for dark photon searches, allowing for a distinctive LHC dark photon phenomen…
We study discovery prospects for a real triplet extension of the Standard Model scalar sector at the Large Hadron Collider (LHC) and a possible future 100 TeV $pp$ collider. We focus on the scenario in which the neutral triplet scalar is stable and contributes to the dark matter relic density. When produced in $pp$ collisions, the charged triplet scalar decays to the neutral component plus a soft pion or soft lepton pair, yielding a disappearing charged track in the detector. We recast current 13TeV LHC searches for disappearing tracks, and find that the LHC presently excludes a real triplet s…
We describe the formalism, and present the results, for a triple-Regge analysis of the available pp and p\bar{p} high-energy data which explicitly accounts for absorptive corrections. In particular, we allow for the gap survival probability, S^2, in single proton diffractive dissociation. Since for pp scattering the value of S^2 is rather small, the triple-Pomeron vertex obtained in this analysis is larger than that obtained in the old analyses where the suppression caused by the absorptive corrections was implicitly included in an effective vertex. We show that the bare triple-Pomeron couplin…
In type II seesaw model of neutrino mass generation, we study a remarkable signal of same-sign tetra-lepton (SS4L) signal at the Large hadron collider. When doubly charged Higgs is lightest, the heavier singly charged or neutral Higgs boson produces a doubly charged Higgs boson through its fast gauge decay. This leads to a novel signature of same-sign tetra-leptons resulting from a pair production of same-sign doubly charged Higgs bosons. We study production cross section for the SS4L signal in parameter space of the mass splitting among triplet components and the triplet vacuum expectation va…
Recently reported diboson excesses at LHC are interpreted to be connected with heavy $WW$ resonance with weak isotopic spin 2. The resonance appears due to the wouldbe anomalous triple interaction of the weak bosons, which is defined by well-known coupling constant $λ$. We obtain estimates for the effect, which qualitatively agree with ATLAS data. Effects are predicted in inclusive production of $W^+W^+, W^+ (Z,γ), W^+ W^-, (Z,γ) (Z,γ), W^- (Z,γ), W^-W^-$ resonances with $M_R \simeq 2\,TeV$, which could be reliably checked at the upgraded LHC with $\sqrt{s}\,=\,13 TeV$. In the framework of an …
In type II seesaw utilized to explain the observed neutrino masses and mixings, one extends the Standard Model (SM) by introducing scalar fields which transform as a triplet under the electroweak gauge symmetry. New scalar couplings involving the Higgs doublet then appear and, as we show, these have important implications for the Higgs boson mass bounds obtained using vacuum stability and perturbativity arguments. We identify, in particular, regions of the parameter space which permit the SM Higgs boson to be as light as 114.4 GeV, the LEP2 bound. The triplet scalars include doubly charged par…
Our main aim in this paper is to present detailed studies to probe the top quark flavor changing neutral current (FCNC) interactions at $tqg$, $tqγ$, $tqH$ and $tqZ (σ^{μν}, γ_μ)$ vertices in the triple-top signal $p p \to t \bar t t \, (\bar t t \bar t)$ at the high energy proposal of Large Hadron Collider (HE-LHC) and future circular hadron-hadron collider (FCC-hh). To this end, we investigate the production of three top quarks which arises from the FCNC couplings taken into account the fast simulation at $\sqrt{s} = 27$ TeV of HE-LHC and 100 TeV of FCC-hh considering the integrated luminosi…
We study anomalous couplings among neutral gauge bosons in $ZZ$ production at the LHC for $\sqrt{s}=13$ TeV in $4$-lepton final state. We use the cross section and polarization asymmetries of the $Z$ boson to estimate simultaneous limits on anomalous coupling using Markov-Chain--Monte-Carlo (MCMC) method for luminosities $35.9$ fb$^{-1}$, $150$ fb$^{-1}$, $300$ fb$^{-1}$ and $1000$ fb$^{-1}$. The $CP$-even polarization asymmetry $A_{x^2-y^2}$ is sensitive mainly to the $CP$-odd couplings $f_4^{Z/γ}$ (quadratically) providing a probe to identify $CP$-odd nature of interaction at the LHC. We fin…
Within 2HDM, sizable deviations of the triple Higgs coupling and the two-photon Higgs width from their SM values can have a common origin. If SM-like scenario for the observed Higgs boson is realized, mentioned deviations can be either visible simultaneously or not observable at the LHC.}
