Search

We study the new $Z'$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through the Higgs-strahlung processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$. We focus on the resonance and non-resonance effects of the $Zh_0, ZH_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3, 4, 5, 6, 7, 10, 30$ TeV and integrated luminosities of ${\cal L}=2, 4, 6, 10, 30$ ${\rm ab^{-1}}$ projected for a future muon collider. The possibility of performing precision measurements for the Higgs bosons $h_0$ and $H_0$ is very promising at the future muon collider. Furthermore, our results may be helpful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying the processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$., Comment: 35 pages, 11 figures

We investigate the anomalous Chromomagnetic Dipole Moment (CMDM), $\hat{\mu}^{BLHM}_t$ of the top quark in the Bestest Little Higgs Model (BLHM). We include new interactions with the involvement of the extended CKM matrix of the BLHM and we explore most of the allowed parameter space, obtaining multiple CMDM in the range of $10^{-4}-10^{-2}$. We consider experimental and model parameter uncertainties to integrate them into all our calculations using a Monte Carlo method. This enables us to determine the extent to which deviations arising from experimental errors can be accommodated within the statistical errors of the model and which relate to the physics framework of the BLHM, guiding future theory, phenomenological, and experimental research.

In the post-LHC era, the muon collider represents a frontier project capable of providing high-energy and high-luminosity leptonic collisions among future lepton-lepton particle accelerators. In addition, it provides significantly cleaner final states than those produced in hadron collisions. With this expectation in mind, in this article, we research the sensitivity of the anomalous neutral gauge boson couplings $Z\gamma\gamma\gamma$, $ZZ\gamma \gamma$, and $ZZZ\gamma$ defined by dimension-8 operators, through the $\mu^+\mu^- \to \mu^+\mu^-Z\gamma$ signal, with the $Z$-boson decaying to neutrino pair. The projections of new physics at the future muon collider with the center-of-mass energy of $\sqrt{s}=10$ TeV, integrated luminosity of ${\cal L}=10$ $\rm ab^{-1}$, and systematic uncertainties of $\delta_{sys}=0\%, 3\%, 5\%$, for extraction of expected sensitivity on the anomalous $f_ {T,j}/\Lambda^4$ couplings at $95\%$ confidence level, are of the order of ${\cal O}(10^{-4}- 10^{-3})$. Compared with the research of the ATLAS and CMS Collaborations on the anomalous quartic gauge couplings, we find that the high-luminosity future muon collider could have better sensitivity.

The presence of multi-boson self-interactions is implied by the non-Abelian gauge structure of the Standard Model (SM). Precise measurements of these interactions allow not only testing the nature of the SM but also new physics contribution arising from the beyond SM. The investigation of these interactions can be approached in a model-independent manner using an effective theory approach, which forms the main motivation of this study. In this paper, we examine the anomalous neutral quartic gauge couplings through the process $\gamma \gamma \rightarrow Z Z$ at the Compact Linear Collider (CLIC) with the center-of-mass energy of $\sqrt{s}=3$ TeV, integrated luminosities of ${\cal L}=5$ $\rm ab^{-1}$. The anomalous neutral quartic gauge couplings is implemented into FeynRules to generate a UFO module inserted into Madgraph to generate both background and signal events. These events are then passed through Pythia 8 for parton showering and Delphes to include realistic detector effects. We obtain that the sensitivities on the anomalous quartic neutral gauge couplings with $95\%$ Confidence Level are given as: $f_{T0}/\Lambda^{4}=[-1.06; 1.08]\times 10^{-3}$ ${\rm TeV^{-4}}$, $f_{T1}/\Lambda^{4}=[-1.06; 1.08]\times 10^{-3}$ ${\rm TeV^{-4}}$,$f_{T2}/\Lambda^{4}=[-1.06; 1.08]\times 10^{-3}$ ${\rm TeV^{-4}}$,$f_{T0}/\Lambda^{4}=[-1.06; 1.08]\times 10^{-3}$ ${\rm TeV^{-4}}$, $f_{T5}/\Lambda^{4}=[-4.08; 4.08]\times 10^{-4}$ ${\rm TeV^{-4}}$ and $f_{T8}/\Lambda^{4}=[-1.10; 1.10]\times10^{-4}$ ${\rm TeV^{-4}}$. Our results on the anomalous quartic neutral gauge couplings are set more stringent sensitivity with respect to the recent experimental limits., Comment: 21 pages, 6 figures

This paper investigates the effects of parameters in the Bestest Little Higgs Model (BLHM) on rare flavor-changing decays of the top quark. As a result, flavor-changing phenomena are introduced in the BLHM for the first time. In this study, we incorporate new flavor mixing terms between the light quarks of the Standard Model (SM) and the fermions and bosons of the BLHM. We compute the one-loop contributions from the heavy quark $(B)$ and the heavy bosons $(W^{\prime\pm}, \phi^{\pm}, \eta^{\pm},H^{\pm})$. Our findings demonstrate that the branching ratios of decays $t\to qV$ and $t\to qh^0$, where $q=u,c$ and $V=Z, \gamma, g $, exhibit improvements compared to their counterparts in the SM, except for the gluon case. Moreover, we observe that the processes with higher sensitivity are $Br(t\to cZ)\sim 10^{-5}$, $Br(t\to c\gamma)\sim 10^{-6}$ and $Br(t \to ch^0) \sim 10^{-8}$ within the appropriate parameter space., Comment: 13 pages and 10 figures

In this paper, using a Bestest Little Higgs Model (BLHM) approach, we obtain bounds on the top-quark electromagnetic and weak dipole moments. These physical observables are sensitive to quantum corrections induced by virtual particles at the one-loop level. The contributions of the virtual particles are obtained from the vertices of scalar bosons, vector bosons, and heavy quarks: $tq_iS_i$, $S_i=h_0, H_0, A_0, \phi^{0}, \eta^{0}, \sigma, H^{\pm}, \phi^{\pm}, \eta^{\pm}$; $tq_iV_i$, $V_i= \gamma, Z, W, Z', W'$; $V q_i\bar q_i$, $V=\gamma,Z$, $q_i=b, t, B, T, T_5, T_6, T^{2/3}, T^{5/3}$; $ V W^{-}_{i}\Phi^{+}_i $, $W_{i} \equiv W, W'$, $\Phi^{\pm}_{i}= \phi^{\pm}, \eta^{\pm}$; $ZZH_i$, $H_i=h_0, H_0$; $ZZ' H_i$; and $VW'W'$. With these new contributions, we evaluated the electroweak dipole moments $ a_t$, $ a^{W}_t $, $ d_t $ and $ d^{W}_{t} $ of the top-quark in the diagonalization schemes $y_2 > y_3$ and $y_2 < y_3$ to the Yukawa couplings. For the BLHM parameters, we choose the following values of $m_{A_0}= 1000$ GeV, $m_{\eta^0}= 100$ GeV, $f=[1000, 3000]$ GeV, $F=[3000, 6000]$ GeV and $\tan\beta=3$, which give the best sensitivity on the electroweak dipole moments of the top-quark in this context: $a_t=1.39 \times 10^{-4} + i\, 6.55 \times 10^{-5}$; $a^{W}_t=6.31 \times 10^{-5} - i\, 1.39 \times 10^{-5}$ for the $y_2 > y_3 $ scenario, while $a_t= 2.12 \times 10^{-4} + i\, 4.49 \times 10^{-5}$; $a^{W}_t= 2.13 \times 10^{-4} - i\, 1.34 \times 10^{-5}$ for the $y_2 < y_3 $ scenario., Comment: 77 pages, 67 figures. arXiv admin note: text overlap with arXiv:2208.09090, arXiv:2202.12738

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., Comment: 34 pages, 15 figures

We carry out a study in the approach of a dimension-8 effective field theory on the anomalous quartic $WW\gamma\gamma$ couplings that arise from the process $pp \to W\gamma\gamma$ at the Future Circular Collider-hadron hadron (FCC-hh). The process is sensitive to the $WW\gamma\gamma$ vertex, and future projections on the anomalous $f_ {M,i}/\Lambda^4$ and $ f_ {T,j}/\Lambda^4$ couplings can be put by measurements of $W\gamma\gamma$ production. We illustrate the physics opportunities and reach of the FCC-hh operating for a high integrated luminosity scenario of ${\cal L}=1, 5, 10, 30$ ${\rm ab}^{-1}$ of proton-proton collisions at a center-of-mass energy of $\sqrt{s}=100$ TeV and systematic uncertainties of $\delta_{sys}=0\%, 3\%, 5\%, 10\%$. Production cross-sections of the signal and the sensitivity constraints on the anomalous $f_ {M,i}/\Lambda^4$ and $ f_ {T,j}/\Lambda^4$ 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 ${\cal O}(10^{-4}-10^1)$. These sensitivity perspectives indicate that the $pp \to W\gamma\gamma$ channel at the FCC-hh has a greater potential to search for the anomalous quartic $WW\gamma\gamma$ couplings and to search for new physics than present colliders., Comment: 29 pages, 8 figures

In this paper, a study is carried out on the $e^-p \to e^-\gamma^* p \to p W^+\gamma \nu_e$ production to probe quartic $W^+W^-\gamma\gamma$ couplings using 10, 100 ${\rm fb^{-1}}$ of $e^-p$ collisions data at $\sqrt{s}$= 1.30, 1.98 GeV at the Large Hadron electron Collider (LHeC) and 100, 1000 ${\rm fb^{-1}}$ with $\sqrt{s}$= 3.46, 5.29 GeV at the Future Circular Collider-hadron electron (FCC-he). Production cross-sections are determined for both at leptonic and hadronic decay channel of the $W$-boson. With the data from future $e^-p$ colliders, it is possible to obtain sensitivity measures at $95\%$ C.L. on the anomalous $f_ {M,i}/\Lambda^4$ and $ f_ {T,i}/\Lambda^4$ couplings which are competitive with the limits obtained by the LHC, as well as with others limits reported in the literature. The production mode $e^-p \to e^-\gamma^* p \to p W^+\gamma \nu_e $ in $e^-p$ collisions offers a window for study the quartic $W^+W^-\gamma\gamma$ electroweak bosons couplings at the LHeC and the FCC-he, which provides a much cleaner collision environment than the LHC., Comment: 27 pages , 10 figures

It is known that the dipole moments of the neutrino lead to important astrophysical and cosmological effects. In this regard, within the context of a $U(1)_{B-L}$ model, we develop and present novel analytical formulas to assess the effects of the anomalous magnetic moment and electric dipole moment of the neutrino on the stellar energy loss rates through some common physical process of pair-annihilation $e^+e^-\to(\gamma, Z, Z^{\prime})\to\nu\bar\nu$. Our results show that the stellar energy loss rates strongly depends on the effective magnetic moment of the neutrino, but also on the parameters which characterize the adopted $U(1)_{B-L}$ model., Comment: 28 pages, 11 figures

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 $WW\gamma\gamma$ couplings in single $W$-boson production in association with a photon. We study the process $ep \to e^-\gamma^* p \to eW\gamma q'X$ via the subprocess $\gamma^* q \to W\gamma q'$. The center-of-mass energies and luminosities of the LHeC are assumed to be $\sqrt{s}=1.30, 1.98$ TeV, ${\cal L}=10-100$ ${\rm fb^{-1} }$ and for the FCC-he $\sqrt{s}=3.46, 5.29$ TeV and ${\cal L}=100-1000$ ${\rm fb^{-1} }$. With these energies and luminosities, we estimate bounds on the anomalous quartic $WW\gamma\gamma$ couplings at $95\%$ C.L., which can be an order of magnitude stringent than the experimental limits report by ATLAS and CMS Collaborations at the LHC., Comment: 28 pages, 10 figures. arXiv admin note: text overlap with arXiv:1211.3100 by other authors

We conducted a study on measuring $W^+W^-$ production and on the sensitivity limits at $95\%$ Confidence Level on thirteen anomalous couplings obtained by dimension-8 operators which are related to the anomalous quartic $WW\gamma\gamma$ couplings. We consider the main $e^-p \to e^-\gamma^*\gamma^*p \to e^-W^+W^-p$ reaction with the sub-process $\gamma^*\gamma^* \to W^+W^-$ at the Large Hadron electron Collider (LHeC) and the Future Circular Collider-hadron electron (FCC-he). For the LHeC, energies of the $e^-$ beams are taken to be $E_e =60$ and 140 GeV and the energy of the $p$ beams is taken to be $E_p = 7$ TeV. For the FCC-he, energies of the $e^-$ beams are taken to be $E_e =60$ and 140 GeV and the energy of the $p$ beams is taken to be $E_p = 50$ TeV, respectively. It is interesting to notice that the LHeC and the FCC-he will lead to model-independent limits on the anomalous quartic $WW\gamma\gamma$ couplings which are one order of magnitude stringent than the CMS Collaboration limits, in addition to being competitive with other limits reported in the literature., Comment: 28 pages, 10 Figures and 13 Tables

We examine the potential of the $e^-p \to e^-\gamma^*p \to e^-W^-q'X$ ($\gamma^*$ is Weizsacker-Willams photon) reaction to probe the non-standard $W^+W^-\gamma$ couplings at the Large Hadron electron Collider (LHeC) and the Future Circular Collider-hadron electron (FCC-he). We find $95\%$ confidence level bounds on the anomalous coupling $\Delta\kappa_\gamma$ and $\lambda_\gamma$ parameters in the view of effective Lagrangian approach with various values of the integrated luminosity. We assume center-of-mass energies of the electron-proton system $\sqrt{s}= 1.30, 1.98, 7.07, 10\hspace{0.8mm}{\rm TeV}$ and luminosities ${\cal L} = 10-1000 \hspace{0.8mm}{\rm fb^{-1}}$. The best limits obtained from the process $e^-p \to e^-\gamma^*p \to e^-W^-q'X$ on the anomalous $\Delta\kappa_\gamma$ and $\lambda_\gamma$ couplings are $\Delta\kappa_\gamma = |0.00069|$ and $\lambda_\gamma = [-0.0099, 0.0054]$. These bounds show that the process under consideration is a good prospect for the searching of the non-standard $\Delta\kappa_\gamma$ and $\lambda_\gamma$ couplings at the LHeC and the FCC-he. In addition, our results provide complementary information on other results for $\Delta\kappa_\gamma$ and $\lambda_\gamma$ couplings., Comment: 16 pages, 4 figures. arXiv admin note: text overlap with arXiv:1910.02307, arXiv:1909.10299

We study the cross-section of production of a single $W^-$ boson in association with a neutrino through the process $e^-p \to e^-\gamma^*p \to \nu_eW^- p$. Additionally, we obtain the anomalous couplings $\Delta\kappa_\gamma$ and $\lambda_\gamma$ of the $W^+W^-\gamma$ vertex at the Large Hadron Electron Collider (LHeC) and the Future Circular Collider Hadron-Electron (FCC-he). The impact of the polarized beam due to the electron is also analyzed. Our best limits for $\Delta\kappa_\gamma$ and $\lambda_\gamma$ at the $95\%$ C.L. are: $\Delta\kappa_\gamma = \pm 0.0017$, $\lambda_\gamma = \pm 0.0053$ (unpolarized electron beam) and $\Delta\kappa_\gamma = \pm 0.0013$, $\lambda_\gamma = \pm 0.0046$ (polarized electron beam) identifying the $W^-$ boson through the hadronic decay channel. In addition, the $e^-\gamma^* \to \nu_eW^-$ collision is one of the clean, pure and simple process to investigate the $W^+W^-\gamma$ coupling without the complications of QCD backgrounds., Comment: 23 pages, 10 figures and 4 tables

We investigate the potential of the Compact Linear Collider (CLIC) to probe the anomalous $W^+W^-\gamma$ coupling in $\gamma\gamma$, $\gamma\gamma^*$ and $\gamma^*\gamma^*$ collisions through the processes $\gamma\gamma\rightarrow W^+ W^-$, $e^+ \gamma \rightarrow e^+ \gamma^{*} \gamma \rightarrow e^+ W^- W^+$ and $e^+ e^-\rightarrow e^+ \gamma^{*} \gamma^{*} e^- \rightarrow e^+ W^- W^+ e^-$. We perform leptonic, semi-leptonic and hadronic decays channels for $W^+W^-$ production in the final state. Taking ${\cal L}=1\hspace{0.8mm}{\rm ab^{-1}}@ \sqrt{s}=0.380\hspace{0.8mm}{\rm TeV}$, ${\cal L}=2.5\hspace{0.8mm}{\rm ab^{-1}}@ \sqrt{s}=1.5\hspace{0.8mm}{\rm TeV}$ and ${\cal L}=5\hspace{0.8mm}{\rm ab^{-1}}@ \sqrt{s}=3\hspace{0.8mm}{\rm TeV}$, based on future CLIC data, the limits for $\Delta\kappa_\gamma$ and $\lambda_\gamma$ might reach up to ${\cal O}(10^{-5}-10^{-4})$ level in the most ideal with 5\hspace{0.8mm}${\rm ab^{-1}}$ set data, which shows a potential advantage compared to those from LHC, Tevatron and LEP data. Thus, our results represent that the processes $\gamma\gamma\rightarrow W^+ W^-$, $e^+ \gamma \rightarrow e^+ \gamma^{*} \gamma \rightarrow e^+ W^- W^+$ and $e^+ e^-\rightarrow e^+ \gamma^{*} \gamma^{*} e^- \rightarrow e^+ W^- W^+ e^-$ at the CLIC are a very good prospect for probing the anomalous $W^+W^-\gamma$ couplings., Comment: 30 pages, 17 figures and 11 tables

In this paper, we consider the electroweak production cross-section of a single anti-top-quark, a neutrino and a photon via charged current through the $e^-p \to e^-\bar b \to \bar t \nu_e \gamma \to \bar t(\to W^- \to (qq', l^- \bar\nu_l)+b) \nu_e\gamma$ signal. Further, we derived the sensitivity expected to the magnetic dipole moment $(\hat a_V)$ and the electric dipole moment $(\hat a_A)$ of the top-quark at the Future Circular Collider Hadron Electron (FCC-he). We present our study for $\sqrt{s}=7.07, 10\hspace{0.8mm}TeV$, ${\cal L}=50, 100, 300, 500, 1000\hspace{0.8mm}fb^{-1}$, $\delta_{sys}=0, 3, 5\hspace{0.8mm}\%$ and $P_{e^-}=0\%, 80\%, -80\%$, respectively. We find that the sensitivity estimated on dipole moments of the top-quark is of the order of magnitude ${\cal O}(10^{-1})$ for both hadronic and leptonic decay modes of $W^-$: $\hat a_V=[-0.2308, 0.2204]$, $|\hat a_A|=0.2259$ at $95\%$ C.L. in the hadronic channel with unpolarized electron beam $P_{e^-}=0\%$. Our results with polarized electron beam for $P_{e^-}=80\%$ and $P_{e^-}=-80\%$ are $\hat a_V=[-0.3428, 0.3321]$, $|\hat a_A|=0.3371$ and $\hat a_V=[-0.2041, 0.1858]$, $|\hat a_A|=0.1939$ at $95\%$ C.L. in the hadronic channel. The corresponding results for the leptonic channel with $P_{e^-}=0\%, 80\% -80\%$ are $\hat a_V=[-0.3067, 0.2963]$, $|\hat a_A|=0.3019$, $\hat a_V=[-0.4563, 0.4456]$, $|\hat a_A|=0.4505$ and $\hat a_V=[-0.2695, 0.2512]$, $|\hat a_A|=0.2592$, respectively. The results for $\hat a_V$ and $\hat a_A$ in the leptonic channel are weaker by a factor of 0.75 than those corresponding to the hadronic channel. Given these prospective sensitivities we highlight that the FCC-he is potential top-quark factory that is particularly well suited to sensitivity study on its dipole moments and with cleaner environments., Comment: 28 pages, 10 figures and 7 tables. arXiv admin note: text overlap with arXiv:1812.08971

In this paper, we present detailed studies on the feasibility at $pp$, $e^-p$ and $e^+e^-$ colliders for model-independent sensitivity estimates on the total cross-section and on the anomalous $\tau^+\tau^-\gamma$ interaction through the tau pair production channels $pp \to p\tau\bar \tau \gamma p$, $e^-p \to e^- \tau\bar \tau \gamma p$ and $e^+e^- \to e^+ \tau\bar \tau \gamma e^-$ at the $\gamma^*\gamma^* \to \tau^+\tau^-\gamma$ mode. Measurements of the anomalous couplings of the $\tau$-lepton $\tilde{a}_\tau$ and $\tilde{d}_\tau$ provide an excellent opportunity to probing extensions of the Standard Model. We estimate the sensitivity at the $95\%$ Confidence Level, and we consider that the $\tau$-lepton decays leptonically or semi-leptonically. We found that of the three considered colliders, the future CLIC at high energy and high luminosity should provide the best sensitivity on the dipole moments of the $\tau$-lepton $\tilde a_\tau= [-0.00128, 0.00105]$ and $ |\tilde{d}_\tau({\rm ecm})|= 6.4394\times 10^{-18}$, which show a potential advantage compared to those from LHC and FCC-he., Comment: 36 pages, 20 Figures, and 5 Tables

In this paper, we study the production of a top-quark in association with a bottom-quark and a electron-neutrino at the Future Circular Collider Hadron Electron (FCC-he) to probe the sensitivity on its magnetic moment $(\hat a_V)$ and its electromagnetic dipole moment $(\hat a_A)$ through the process $e^-p \to e^-\gamma p \to \bar t \nu_e b p$. Assuming a large amount of collisions, as well as of data with cleaner environments, the FCC-he is an excellent option to study new physics, such as the $\hat a_V$ and $\hat a_A$. For our sensitivity study on $\hat a_V$ and $\hat a_A$, we consider center-of-mass energies $\sqrt{s}= 7.07, 10\hspace{0.8mm}TeV$ and luminosities ${\cal L}=50, 100, 300, 500, 1000\hspace{0.8mm}fb^{-1}$. In addition, we apply systematic uncertainties $\delta_{sys}=0\%, 3\%, 5\%$ and we consider unpolarized and polarized electron beam. Our results show that the FCC-he is a very good perspective to probe the $\hat a_V$ and $\hat a_A$ at high-energy and high-luminosity frontier., Comment: 19 pages, 14 Figures, 6 Tables; v2: version published in NPB. arXiv admin note: text overlap with arXiv:1811.10462

The measurement of the top-quark anomalous electromagnetic couplings is one of the most important goals of the top-quark physics program in the present and future collider experiments. This would provide direct information on the non-standard interactions of the top-quark. We study a top-quark pair production scenario at the Future Circular Collider Hadron-Electron (FCC-he) through $e^-p \to e^-\gamma^*\gamma^*p \to e^-t\bar t p$ collisions, which will provide information about sensitivities on anomalous $\hat a_V$ and $\hat a_A$ couplings at $95\%\hspace{0.8mm}C.L.$, and the possibility of probing new physics. Energy of the $e^-$ beams is taken to be $E_e=250\hspace{0.8mm}GeV$ and $500\hspace{0.8mm}GeV$ and the energy of the $p$ beams is taken to be $E_p=50\hspace{0.8mm}TeV$, with these energies the FCC-he may sensitivity estimates on top-quark electromagnetic dipole moments $\hat a_V$ and $\hat a_A$ of the order ${\cal O}(10^{-2}-10^{-1})$., Comment: 27 Pages, 12 Figures and 7 Tables, version to be published on EPJP. arXiv admin note: text overlap with arXiv:1702.03708

Using the effective Lagrangian formalism, the anomalous magnetic and electric dipole moments of the tau-lepton in the $\mu^{+}\mu^{-} \rightarrow \mu^{+}\gamma^{*} \gamma^{*} \mu^{-}\rightarrow \mu^{+}\tau \bar{\tau}\mu^{-}$ process at the future muon colliders at the $\sqrt{s}=1.5, 3$ and $6$ TeV are investigated. In addition, the bounds at the $95\%$ confidence level on the dipole moments of the tau-lepton using different integrated luminosities are estimated. It is shown that the $\mu^{+}\mu^{-} \rightarrow \mu^{+}\gamma^{*} \gamma^{*} \mu^{-}\rightarrow \mu^{+}\tau \bar{\tau}\mu^{-}$ process leads to a remarkable improvement in the existing experimental bounds on the anomalous magnetic and electric dipole moments of the tau-lepton., Comment: 26 Pages, 19 Figures, 3 Tables

We conduce a study to probe the sensitivity of the process $e^+e^-\rightarrow (\gamma, Z) \to \nu_\tau \bar \nu_\tau \gamma$ to the total cross section, the magnetic moment and the electric dipole moment of the tau-neutrino in a model-independent way. For this study, the beam polarization facility at the Compact Linear Collider (CLIC) along with the typical center-of-mass energies $\sqrt{s}=380-3000\hspace{0.8mm}GeV$ and integrated luminosities ${\cal L}=10-3000\hspace{0.8mm}fb^{-1}$ is considered. We estimate the sensitivity at the $95\%\hspace{1mm}$ Confidence Level (C.L.) and systematic uncertainties $\delta_{sys}=0, 5, 10\hspace{1mm}\%$ on the dipole moments of the tau-neutrino. It is shown that the process under consideration $e^+e^-\rightarrow (\gamma, Z) \to \nu_\tau \bar \nu_\tau \gamma$ is a good prospect for study the dipole moments of the tau-neutrino at the CLIC. Also, our study illustrates the complementarity between CLIC and other $e^+e^-$ and $pp$ colliders in probing extensions of the Standard Model, and shows that the CLIC at high energy and high luminosity provides a powerful means to sensitivity estimates for the electromagnetic dipole moments of the tau-neutrino., Comment: 24 pages, 11 figures and 6 tables. arXiv admin note: text overlap with arXiv:1807.00238

We establish model independent bounds on the anomalous magnetic and electric dipole moments of the tau-lepton using the two-photon processes $\gamma\gamma \to \tau^+\tau^-$ and $\gamma\gamma \to \tau^+\tau^-\gamma$. We use ${\cal L}=10, 50, 100, 300, 500, 1000, 1500, 2000, 3000 \hspace{0.8mm}fb^{-1}$ of data collected with the future $e^+e^-$ linear collider such as the CLIC at $\sqrt{s}=380, 1500, 3000 \hspace{0.8mm}GeV$ and we consider systematic uncertainties of $\delta_{sys}=0, 3, 5\hspace{1mm}\%$. Precise bounds at $95\%$ C. L. on the anomalous dipole moments to the tau-lepton $-0.00015\leq \tilde{a}_\tau \leq 0.00017$ and $|\tilde{d}_\tau(ecm)|=9.040\times 10^{-19}$ are set from our study. Our results show that the processes under consideration are a very good prospect for probing the dipole moments of the tau-lepton at the future $e^+e^-$ linear collider at the $\gamma\gamma$ mode., Comment: 38 pages, 26 figures

In this paper the production cross section $pp\rightarrow (\gamma, Z) \to \nu_\tau \bar \nu_\tau \gamma+X$ in $pp$ collisions at $\sqrt{s}=8, 13, 14, 33TeV$ is presented. Furthermore, we estimate bounds at the $95\%C. L.$ on the dipole moments of the tau-neutrino using integrated luminosity of ${\cal L}=20, 50, 100, 200, 500, 1000, 3000 fb^{-1}$ collected with the ATLAS detector at the LHC and we consider systematic uncertainties of $\delta_{sys}=0, 5, 10\%$. It is shown that the process under consideration is a good prospect for probing the dipole moments of the tau-neutrino at the LHC., Comment: 20 pages, 12 figures

In this work we study the sensitivity on the anomalous magnetic and electric dipole moments of the tau-neutrino in the framework of the $SU(2)_L\times U(1)_Y\times U(1)_{B-L}$ electroweak model at future $e^+e^-$ linear colliders as the ILC and CLIC. For our study we consider the process $e^{+}e^{-}\rightarrow ( Z, Z', \gamma) \to \nu_\tau \bar \nu_\tau \gamma$. For center-of-mass energies of $\sqrt{s}=1000-3000\hspace{0.8mm}GeV$ and integrated luminosities of ${\cal L}=500-2000\hspace{0.8mm}fb^{-1}$, we derive $95 \% \hspace{1mm}$ C.L. limits on the dipole moments $|\mu_{\nu_\tau}(\mu_B)| \leq 6.28 \times 10^{-9}$ and $|d_{\nu_\tau}(e cm)| \leq 1.21 \times 10^{-21}$ improve the existing limits by two or three orders of magnitude. Our study complements other studies on the dipole moments of the tau-neutrino at hadron and $e^+e^-$ colliders., Comment: 28 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1606.04144

We calculate the stellar energy loss due to neutrino-pair production in $e^+e^-$ annihilation in the context of a 331 model, a left-right symmetric model and a simplest little Higgs model in a way that can be used in supernova calculations. We also present some simple estimates which show that such process can act as an efficient energy loss mechanism in the shocked supernova core. We find that the stellar energy loss is almost independent on the parameters of the models in the allowed range for these parameters. This work complements other studies on the stellar energy loss rate in $e^+e^-$ annihilation., Comment: 28 pages, 6 figures. arXiv admin note: text overlap with arXiv:1205.6003, arXiv:1611.09337 by other authors

We study the phenomenology of the light and heavy Higgs boson production and decay in the context of a $U(1)_{B-L}$ extension of the Standard Model with an additional $Z'$ boson at future $e^+e^-$ linear colliders with center-of-mass energies of $\sqrt{s}=500-3000\hspace{0.8mm}GeV$ and integrated luminosities of ${\cal L}=500-2000\hspace{0.8mm}fb^{-1}$. The study includes the processes $e^{+}e^{-}\rightarrow (Z, Z') \to Zh$ and $e^{+}e^{-}\rightarrow (Z, Z') \to ZH$, considering both the resonant and non-resonant effects. We find that the total number of expected $Zh$ and $ZH$ events can reach 909,124 and 97,487, respectively, which is a very optimistic scenario and thus it would be possible to perform precision measurements for both Higgs bosons $h$ and $H$, as well as for the $Z'$ boson in future high-energy and high-luminosity $e^+e^-$ colliders experiments. Our study complements other studies on the B-L model and on the Higgs-strahlung processes $e^{+}e^{-}\rightarrow (Z, Z') \to Zh$ and $e^{+}e^{-}\rightarrow (Z, Z') \to ZH$., Comment: 39 pages, 15 figures; To be published in The Journal of Physics G: Nuclear and Particle Physics. arXiv admin note: substantial text overlap with arXiv:1506.07575; text overlap with arXiv:1106.4462 by other authors

We study the prospects of the B-L model with an additional $Z'$ boson to be a Higgs boson factory at high-energy and high-luminosity linear electron positron colliders, such as the ILC and CLIC, through the Higgs-strahlung process $e^{+}e^{-}\rightarrow (Z, Z') \to Zh$, including both the resonant and non-resonant effects. We evaluate the total cross section of $Zh$ and we calculate the total number of events for integrated luminosities of 500-2000\hspace{0.8mm}$fb^{-1}$ and center of mass energies between 500 and 3000\hspace{0.8mm}$GeV$. We find that the total number of expected $Zh$ events can reach $10^6$, which is a very optimistic scenario and it would be possible to perform precision measurements for both the $Z'$ and Higgs boson in future high-energy $e^+e^-$ colliders experiments., Comment: 21 pages, 11 figures

We study pair-production as well as the triple self-couplings of the neutral Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) at the Future International Linear $e^{+}e^{-}$ Collider (ILC) and Compact Linear Collider (CLIC). The analysis is based on the reactions $e^{+}e^{-}\to b \bar b h_ih_i, t \bar t h_ih_i$ with $h_i=h, H, A$. We evaluate the total cross-section for both $b\bar bh_ih_i$, $t\bar th_ih_i$ and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. We vary the triple couplings $\kappa\lambda_{hhh}$, $\kappa\lambda_{Hhh}$, $\kappa\lambda_{hAA}$, $\kappa\lambda_{HAA}$, $\kappa\lambda_{hHH}$ and $\kappa\lambda_{HHH}$ within the range $\kappa=-1$ and +2. The numerical computation is done for the energies expected at the ILC with a center-of-mass energy 500, 1000, 1600 $GeV$ and a luminosity 1000 $fb^{-1}$. The channels $e^{+}e^{-}\to b \bar b h_ih_i$ and $e^{+}e^{-}\to t \bar t h_ih_i$ are also discussed to a center-of-mass energy of 3 $TeV$ and luminosities of 1000 $fb^{-1}$ and 5000 $fb^{-1}$., Comment: 26 pages, 11 figures

We study the sensitivity for testing the anomalous triple gauge couplings $ZZ\gamma$ and $Z\gamma\gamma$ via the process $e^+e^-\to \nu \bar\nu \gamma$ at high energy linear colliders. For integrated luminosities of 500 $fb^{-1}$ and center of mass energies between 0.5 and 1.5 $TeV$, we find that this process can provide tests of the triple neutral gauge boson couplings of order $10^{-4}$, one order of magnitude lower than the standard model prediction., Comment: 12 pages, 6 figures

We analyzed the triple Higgs boson self-coupling at future $e^{+}e^{-}$ colliders energies, with the reactions $e^{+}e^{-}\to b \bar b HH, t \bar t HH$. We evaluate the total cross-sections for both $b\bar bHH$ and $t\bar tHH$, and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. We vary the triple coupling $\kappa\lambda_{3H}$ within the range $\kappa=-1$ and +2. The numerical computation is done for the energies expected to be available at a possible Future Linear $e^{+}e^{-}$ Collider with a center-of-mass energy $800, 1000, 1500$ $GeV$ and a luminosity 1000 $fb^{-1}$. Our analysis is also extended to a center-of-mass energy 3 $TeV$ and luminosities of 1000 $fb^{-1}$ and 5000 $fb^{-1}$. We found that for the process $e^{+}e^{-}\to b \bar b HH$, the complete calculation differs only by 3% from the approximate calculation $e^{+}e^{-}\to ZHH(Z\to b\bar b)$, while for the process $e^{+}e^{-}\to t \bar tHH$, the expected number of events, considering the decay products of both $t$ and $H$, is not enough to obtain an accurate determination of the triple Higgs boson self-coupling., Comment: 19 pages, 12 figures

Using the experimental value for the rate $R^{LEP} _{exp}=\Gamma_{inv}/\Gamma_{l\bar l}=5.942\pm 0.016$, we derive constraints on the number of light neutrino species with the invisible width method in the framework of a left-right symmetric model (LRSM) and a $E_6$ superstring model as a function of their respective mixing angles for the neutral vector gauge bosons. Using the above LEP result we get the constraints $-1.6\times 10^{-3}\leq\phi \leq 1.1\times 10^{-3}$ and $-1.3\times 10^{-2}\leq\phi_{E_6} \leq 0.4\times 10^{-2}$, which are stronger than those obtained in previous studies of these models., Comment: 9 pages, 4 figures, Submit to Modern Physics Letter A

Using the experimental values for the rates $R^{LEP} _{exp}=\Gamma_{inv}/\Gamma_{l\bar l}=5.942\pm 0.016$, $R^{Giga-Z_1}=\Gamma_{inv}/\Gamma_{l\bar l}=5.942\pm 0.012$ (most conservative) and $R^{Giga-Z_1}=\Gamma_{inv}/\Gamma_{l\bar l}=5.942\pm 0.006$ (most optimistic) we derive constraints on the number of neutrinos light species $(N_\nu)_{LRSM}$ with the invisible width method in the framework of a left-right symmetric model (LRSM) as a function of the LR mixing angle $\phi$. Using the LEP result for $N_\nu$ we may place a bound on this angle, $-1.6\times 10^{-3}\leq\phi \leq 1.1\times 10^{-3}$, which is stronger than those obtained in previous studies of the LRSM., Comment: 8 pages, 3 figures

We obtain limits on the electromagnetic and weak dipole moments of the tau-lepton in the framework of a Left-Right symmetric model (LRSM) and a class of $E_6$ inspired models with an additional neutral vector boson $Z_\theta$. Using as an input the data obtained by the L3 and OPAL Collaborations for the reaction $e^+e^-\to \tau^+\tau^-\gamma$, we get a stringent limit on the LRSM mixing angle $\phi$, $-1.66\times 10^{-3}< \phi<1.22\times 10^{-3}$, which in turn induces bounds on the tau weak dipole moments which are consistent with the bounds obtained recently by the DELPHI and ALEPH Collaborations from the reaction $e^+e^-\to \tau^+\tau^-$. We also get similar bounds for the weak dipole moments of the tau lepton in the framework of $E_6$ superstring models., Comment: 18 pages, 5 figures

We obtain bounds on the anomalous magnetic and electric dipole moments of the tau-neutrino through the reaction $e^{+}e^{-}\to \nu \bar \nu \gamma$ at the $Z_1$-pole in the framework of a Left-Right symmetric model and a class of $E_6$ inspired models with an additional neutral vector boson $Z_\theta$. We use the data collected by the L3 Collaboration at LEP. For the parameters of the $E_6$ model we consider the mixing angle $\theta_{E_6}=37.8^o$ and $M_{Z_\theta}=7M_{Z_1}$. We find that our bounds are of the same order of magnitude as those obtained in other extensions of the Standard Model., Comment: 17 pages, 2 figure

We study the triple Higgs self-coupling at future $e^{+}e^{-}$ colliders energies, with the reactions $e^{+}e^{-}\to b \bar b HH$ and $e^{+}e^{-}\to t \bar t HH$. We evaluate the total cross section of $b\bar bHH$, $t\bar tHH$ and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. The sensitivity of the triple Higgs coupling is considered in the Higgs mass range 110-190 $GeV$, for the energy which is expected to be available at a possible Next Linear $e^{+}e^{-}$ Collider with a center-of-mass energy $800, 1000, 1500$ $GeV$ and luminosity 1000 $fb^{-1}$., Comment: 15 pages, 10 figures

In a previous paper, we studied the Higgs pair production in the standard model with the reaction $e^{+}e^{-}\to t \bar t HH$. Based on this, we study the Higgs pair production via $e^{+}e^{-}\to b \bar b HH$. We evaluate the total cross section of $b\bar bHH$ and calculate the number total of events considering the complete set of Feynman diagrams at tree-level, and compare this process with the process $e^{+}e^{-}\to t \bar t HH$. The numerical computation is done for the energy which is expected to be available at a possible Next Linear $e^{+}e^{-}$ Collider with a center-of-mass energy $800, 1000, 1600$ $GeV$ and luminosity 1000 $fb^{-1}$., Comment: 12 pages, 6 figures

Limits on the anomalous magnetic moment and the electric dipole moment of the $\tau$ lepton are calculated through the reaction $e^{+}e^{-}\to \tau^+ \tau^- \gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\phi$, the effect of this angle on the dipole moments is quite small., Comment: 15 pages, 3 figures

Bounds on the anomalous magnetic moment and the electric dipole moment of the $\tau$-neutrino are calculated through the reaction $e^{+}e^{-}\to \nu \bar \nu \gamma$ at the $Z_1$-pole, and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. We find that the bounds are almost independent of the mixing angle $\phi$ of the model in the allowed experimental range for this parameter. In addition, the analytical and numerical results for the cross-section have never been reported in the literature before., Comment: 17 pages, 2 figures. Accepted for publication in Phys. Rev. D

We study the Higgs pair-production in the Standard Model of the strong and electroweak interactions at future $e^{+}e^{-}$ collider energies, with the reaction $e^{+}e^{-}\to t \bar t HH$. We evaluated the total cross section of $t\bar tHH$ and calculate the number total of events considering the complete set of Feynman diagrams at tree-level. The numerical computation is done for the energy which is expected to be available at a possible Next Linear $e^{+}e^{-}$ Collider: with center-of-mass energy $800, 1600$ $GeV$ and luminosity 1000 $fb^{-1}$., Comment: 8 pages, 4 figures

We assume that a massive Dirac neutrino is characteized by two phenomenological parameters, a magnetic moment, and a charge radius, and we calculate the cross-section of the scattering $e^+e^-\to \nu \bar \nu$ in a left-right symmetric model. We also analyze the angular distribution of the neutrino (antineutrino) with respect to the original direction of the electron (positron) to different state of helicity of the neutrino. We find that the favored directions for the neutrino (antineutrino) with respect to the electron (positron) is forward $(\theta =0)$ and backward $(\theta= \pi)$, and is not very probable in the perpendicular direction $(\theta = \frac{\pi}{2})$. The calculation is for $\phi = -0.005$ and $M_{Z_2}=500$ $GeV$, parameters of the Left-Right symmetric model., Comment: 16 pages, 7 figures

We start from a Left-Right Symmetric Model and we analyze the beta decay of the free neutron $n\to p+e^{-}+\bar{\nu}_{e}$. We applied this model to incorporate the right currents, whereby we propose an amplitude whose leptonic part contains the parameter $\lambda $ defined as left-right asymmetry parameter which measures the parity violation. The analysis consists of seeing how the spectrum of energy of the electrons, the total rate of decay, and the lifetime $\tau $ of the neutron are affected by the left-right asymmetry parameter, besides taking into account corrections of mass, that is, $m_{e}\neq 0$, $m_{p}\neq m_{n}$, and the recoil of the proton., Comment: 23 pages, 4 figures

We start from a Left-Right Symmetric Model with massive Dirac neutrinos, with an electromagnetic structure that consists of a charge radius, and we calculate the cross-section of the scattering $\nu_{\mu}e^-\to \nu_{\mu}e^-$. Subsequently, we calculate the simultaneous contribution of the charge radius, of the additional $Z_{2}$ heavy gauge boson and of the mixing angle $\phi$ parameter of the model at the constants of couplings $(g^{\nu e}_{V})_{LRSM}$ and $(g^{\nu e}_{A})_{LRSM}$., Comment: 13 pages, 7 figures

insert abstract here We study the production of the Higgs bosons predicted in the Minimal Supersymmetric extension of the Standard Model $(h^0, H^0, A^0, H^\pm)$, with the reactions $e^{+}e^{-}\to b\bar b h^0 (H^0, A^0)$, and $e^+e^-\to \tau^-\bar \nu_\tau H^+, \tau^+\nu_\tau H^-$, using the helicity formalism. We evaluate cross section of $h^0, H^0, A^0$ and $H^\pm$ in the limit when $\tan\beta$ is large. The numerical computation is done considering two stages of a possible Next Linear $e^{+}e^{-}$ Collider: the first with $\sqrt{s}=500$ $GeV$ and design luminosity 50 $fb^{-1}$, and the second with $\sqrt{s}=1$ $TeV$ and luminosity 100-200 $fb^{-1}$., Comment: 16 pages, 11 figures

We investigate the possibility of detecting the Higgs bosons predicted in the Minimal Supersymmetric extension of the Standard Model $(h^0, H^0, A^0, H^\pm)$, with the reactions $e^{+}e^{-}\to b\bar b h^0 (H^0, A^0)$, and $e^+e^-\to \tau^-\bar \nu_\tau H^+, \tau^+\nu_\tau H^-$, using the helicity formalism. We analyze the region of parameter space $(m_{A^0}-\tan\beta)$ where $h^0, H^0, A^0$ and $H^\pm$ could be detected in the limit when $\tan\beta$ is large. The numerical computation is done considering two stages of a possible Next Linear $e^{+}e^{-}$ Collider: the first with $\sqrt{s}=500$ $GeV$ and design luminosity 50 $fb^{-1}$, and the second with $\sqrt{s}=1$ $TeV$ and luminosity 100-200 $fb^{-1}$., Comment: 12 latex pages, 12 figures