This paper was converted on www.awesomepapers.org from LaTeX by an anonymous user.
Want to know more? Visit the Converter page.

Investigation of the Higgs boson anomalous FCNC interactions in the simple 3-3-1 model

D. T. Huonga [email protected]    N. T. Duy a,b a Institute of Physics, VAST, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam
b Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam
[email protected]
Abstract

We study phenomenological constraints on the simple 3-3-1 model with flavor-violating Yukawa couplings. Both Higgs triplets couple to leptons and quarks, which generates flavor-violating signals in both lepton and quark sectors. We have shown that this model allows for a large Higgs lepton flavor-violating rate decay hμτh\rightarrow\mu\tau and may reach perfect agreements with other experimental constraints such as τμγ\tau\rightarrow\mu\gamma and (g2)μ(g-2)_{\mu}. The contributions of flavor-changing neutral current couplings, Higgs–quark–quark couplings, mixing to the mesons are investigated. Br(hqq)(h\rightarrow qq^{\prime}) can be enhanced acknowledging the measurements of meson mixing. The branching ratio for tqht\rightarrow qh can reach up to 10310^{-3}, but it could be as low as 10810^{-8}.

pacs:
12.60.-i, 95.35.+d

I Introduction

The discovery of the Higgs boson in July 2012 at the Large Hadron Collider (LHC) atlascms has opened up a new area of the direct search for physics beyond the Standard Model (SM). The new physics may become manifest in the form of Higgs boson properties different from those predicted by the SM. One of those properties is expressed by non-standard interactions of the newly discovered 125GeV125\ \text{GeV} Higgs-like resonance such as flavor-violating Higgs couplings to leptons and quarks. These interactions could induce non-zero lepton flavor-violating (LFV) Higgs boson decays, such as hliljh\rightarrow l_{i}l_{j} with iji\neq j, indeed the most stringent limits on the branching ratios of LFV decay of the SM-like Higgs boson Br(hμτ,eτ)<𝒪(103)(h\rightarrow\mu\tau,e\tau)<\mathcal{O}(10^{-3}), from the CMS Collaboration using data collected at a center-of-mass energy of 13 TeV. In contrast, the situation is somewhat more complicated in the quark sector by the process, which is related to the flavor-violating Higgs couplings involving a top quark, which seems to be outside the present reach of LHC. It leads to the experimental upper limits on flavor-changing neutral current (FCNC) decay of top quarks at 95%95\% CL FCNC22 . Besides, the strongest indirect bound on FCNC quark–quark–Higgs couplings came from a measurement of meson oscillations. This bound can be translated into the upper bound on the branching fraction of the flavor-violating decay of the Higgs boson to the light quarks FCNC23 .

In the physics beyond SM, different mechanisms can yield the non-standard interactions of the SM-like Higgs boson that predict the flavor-violating processes, which could get close to the sensitivities of future accelerators. Among all the possibilities, the models based on the gauge symmetry SU(3)C×SU(3)L×U(1)X(331)SU(3)_{C}\times SU(3)_{L}\times U(1)_{X}\ (3-3-1), called the 3-3-1 model 331m ; FGN ; 331r ; ecn331 ; r331 , are rich with FCNC physics, including both quark and lepton sectors FCNC24 ; FCNC25 . Besides that, the 3-3-1 model can solve the current issues of physics such as dark matter 331DM ; 331DM1 ; m331 , neutrino mass and mixing 331Neutrino , the number of fermion generation FGN , strong CP conservation 331StrongCP , electric charge quantization 331charge . Improved versions of simplifying for solving current experimental results at the larger hadron collider (LHC) have been proposed. Differences in each version make manifest the scalar and fermion contents. The simple 3-3-1 version is an improvement of the minimal and reduced 3-3-1 version 331m ; r331 , which contains the smallest fermion and scalar contents m331 . This improvement allows a simple 3-3-1 model to overcome the disadvantages of the previous models Simple331m . The simple 3-3-1 model is realistic on introducing the inner Higgs triplets m331 . The presence of the inert Higgs triplet not only solves the dark matter problem but also can explain the experimental ρ\rho-parameter m331 . We would like to note that without introducing the inert Higgs triplets, the new physics contribution to the ρ\rho-parameter coming from the normal sector is very tiny and can be negligible DongSi . However, the inert Higgs triplet gives the contribution to the ρ\rho-parameter via a loop effect that is significant, and which is comparable with the global fit, as mentioned in m331 .

The constraint on the SM-like Higgs boson at the LHC was studied in m331 . However, one did not consider the implications for collider searches of precision physics bound on the SM-like Higgs bosons with flavor-violating couplings. The simple 3-3-1 model consists of two Higgs triplets in the normal sector and the leptons and quarks couple to both Higgs triplets via general Yukawa matrices (including both normalizable-operators and non-renormalized operators). So, it allows for flavor-changing tree-level couplings of the physical Higgs bosons. It may be able to accommodate large branching ratios for lepton and quark flavor-violating decay of the SM-like Higgs bosons such as hμτ,hqiqjh\rightarrow\mu\tau,h\rightarrow q_{i}q_{j}, with qi,jq_{i,j} being a light quark, and the top-quark decays tqht\rightarrow qh. Along with those decays, the decay τμγ\tau\rightarrow\mu\gamma and the anomalous magnetic moment of the muon (g2)μ(g-2)_{\mu} also are constrained by the lepton flavor-violating Higgs couplings. The neutral Higgs bosons contribute to (g2)μ(g-2)_{\mu} at the one-loop level, with both flavors violating vertices, while they contribute to the τμγ\tau\rightarrow\mu\gamma at one loop and two loops. We hope that these contributions can be fitted to the (g2)μ(g-2)_{\mu} discrepancy and may reach the current bound on Br(τμγ)(\tau\rightarrow\mu\gamma) of the experiment. So, we are going to focus on studying the contribution of the flavor-violating interactions into some decay channels of the SM-like Higgs boson, heavy quark, and lepton and on (g2)μ(g-2)_{\mu}.

In Sect.II, we briefly review the simple 3-3-1 model. We discuss the constraints from precision flavor observables, such as hμτ,τμγh\rightarrow\mu\tau,\tau\rightarrow\mu\gamma, and (g2)μ(g-2)_{\mu} in Sect.III. Sect.IV investigates the contributions of flavor violating Higgs couplings to quarks into the meson mixing masses. Based on that research, we show that the branching ratios hqi,qjh\rightarrow q_{i},q_{j}, with i,j3i,j\neq 3 might agree with the upper bound of the experiment. The top-quark decay modes tqiht\rightarrow q_{i}h also are studied in Sect.IV. Finally, we summarize our results and draw conclusions in Sect.V.

II Simple 3-3-1 model

The simple model is a combination of the reduced 3-3-1 model r331 and the minimal 3-3-1 model 331m in which the lepton and scalar contents are minimal  m331 . The fermion content which is anomaly free is defined as 331m

ψaL\displaystyle\psi_{aL} \displaystyle\equiv (νaLeaL(eaR)c)(1,3,0),\displaystyle\left(\begin{array}[]{c}\nu_{aL}\\ e_{aL}\\ (e_{aR})^{c}\end{array}\right)\sim(1,3,0), (4)
QαL\displaystyle Q_{\alpha L} \displaystyle\equiv (dαLuαLJαL)(3,3,1/3),Q3L(u3Ld3LJ3L)(3,3,2/3),\displaystyle\left(\begin{array}[]{c}d_{\alpha L}\\ -u_{\alpha L}\\ J_{\alpha L}\end{array}\right)\sim(3,3^{*},-1/3),\hskip 14.22636ptQ_{3L}\equiv\left(\begin{array}[]{c}u_{3L}\\ d_{3L}\\ J_{3L}\end{array}\right)\sim\left(3,3,2/3\right), (11)
uaR\displaystyle u_{aR} \displaystyle\sim (3,1,2/3),daR(3,1,1/3),\displaystyle\left(3,1,2/3\right),\hskip 14.22636ptd_{aR}\sim\left(3,1,-1/3\right),
JαR\displaystyle J_{\alpha R} \displaystyle\sim (3,1,4/3),J3R(3,1,5/3),\displaystyle\left(3,1,-4/3\right),\hskip 14.22636ptJ_{3R}\sim\left(3,1,5/3\right),

where a=1,2,3a=1,2,3 and α=1,2\alpha=1,2 are family indices. The quantum numbers in parentheses are given upon assuming 3-3-1 symmetries, respectively. The third generation of quarks is arranged differently from the two remaining generations to obtain appropriate FCNC contributions when the new energy scale is blocked by the Landau pole. Due to the proposed fermion content, the minimal and unique scalars sector is introduced as follows:

η=(η10η2η3+)(1,3,0),χ=(χ1χ2χ30)(1,3,1),\displaystyle\eta=\left(\begin{array}[]{c}\eta^{0}_{1}\\ \eta^{-}_{2}\\ \eta^{+}_{3}\end{array}\right)\sim(1,3,0),\hskip 14.22636pt\chi=\left(\begin{array}[]{c}\chi^{-}_{1}\\ \chi^{--}_{2}\\ \chi^{0}_{3}\end{array}\right)\sim(1,3,-1), (18)

with VEVs η10=u2,χ30=w2\langle\eta_{1}^{0}\rangle=\frac{u}{\sqrt{2}},\langle\chi_{3}^{0}\rangle=\frac{w}{\sqrt{2}}. In order to reveal candidates for dark matter, an inert scalar multiplet ϕ=η,χ\phi=\eta^{\prime},\chi^{\prime} or σ\sigma, ensured by an extra Z2Z_{2} symmetry, ϕϕ\phi\rightarrow-\phi, is introduced m331 . Because of Z2Z_{2} symmetry, the inert and normal scalars do not mix. The physical eigenstates and mass of normal scalars are considered in terms of VsimpleV_{\text{simple}} given in m331 . The Higgs triplets can be decomposed as ηT=(u2 0 0)+(S1+iA12η2η3+)\eta^{T}=(\frac{u}{\sqrt{2}}\ 0\ 0)+(\frac{S_{1}+iA_{1}}{\sqrt{2}}\ \eta^{-}_{2}\ \eta^{+}_{3}) and χT=(0 0w2)+(χ1χ2S3+iA32)\chi^{T}=(0\ 0\ \frac{w}{\sqrt{2}})+(\chi^{-}_{1}\ \chi^{--}_{2}\ \frac{S_{3}+iA_{3}}{\sqrt{2}}). The fields A1,A3A_{1},A_{3}, η2±,χ±±\eta_{2}^{\pm},\chi^{\pm\pm} and the decomposed state GX±=cθχ1±sθη3±G_{X}^{\pm}=c_{\theta}\chi_{1}^{\pm}-s_{\theta}\eta^{\pm}_{3} are massless Goldstone bosons eaten by ZZ, Z,W±,Y±±Z^{\prime},W^{\pm},Y^{\pm\pm}, and X±X^{\pm} gauge bosons, respectively. The physical scalar fields with respective masses are identified as follows:

hcξS1sξS3,mh2=λ1u2+λ2w2(λ1u2λ2w2)2+λ32u2w24λ1λ2λ322λ2u2,\displaystyle h\equiv c_{\xi}S_{1}-s_{\xi}S_{3},\hskip 14.22636ptm^{2}_{h}=\lambda_{1}u^{2}+\lambda_{2}w^{2}-\sqrt{(\lambda_{1}u^{2}-\lambda_{2}w^{2})^{2}+\lambda^{2}_{3}u^{2}w^{2}}\simeq\frac{4\lambda_{1}\lambda_{2}-\lambda^{2}_{3}}{2\lambda_{2}}u^{2},
HsξS1+cξS3,mH2=λ1u2+λ2w2+(λ1u2λ2w2)2+λ32u2w22λ2w2,\displaystyle H\equiv s_{\xi}S_{1}+c_{\xi}S_{3},\hskip 14.22636ptm^{2}_{H}=\lambda_{1}u^{2}+\lambda_{2}w^{2}+\sqrt{(\lambda_{1}u^{2}-\lambda_{2}w^{2})^{2}+\lambda^{2}_{3}u^{2}w^{2}}\simeq 2\lambda_{2}w^{2}, (19)
H±cθη3±+sθχ1±,mH±2=λ42(u2+w2)λ42w2.\displaystyle H^{\pm}\equiv c_{\theta}\eta^{\pm}_{3}+s_{\theta}\chi^{\pm}_{1},\hskip 14.22636ptm^{2}_{H^{\pm}}=\frac{\lambda_{4}}{2}(u^{2}+w^{2})\simeq\frac{\lambda_{4}}{2}w^{2}.

ξ\xi is the S1S_{1}S3S_{3} mixing angle, while θ\theta is that of χ1\chi_{1}η3\eta_{3} and they are defined via tθ=uw,t2ξ=λ3uwλ2w2λ1u2λ3uλ2w.t_{\theta}=\frac{u}{w},t_{2\xi}=\frac{\lambda_{3}uw}{\lambda_{2}w^{2}-\lambda_{1}u^{2}}\simeq\frac{\lambda_{3}u}{\lambda_{2}w}. Here, we note that cx=cos(x),sx=sin(x),tx=tan(x)c_{x}=\cos(x),\ s_{x}=\sin(x),\ t_{x}=\tan(x), and so forth, for any xx angle. The hh is identified with the Higgs boson discovered at the LHC and HH and H±H^{\pm} are new neutral and singly charged Higgs bosons, respectively,

Because of the conservation of Z2Z_{2} symmetry, the inert multiplets do not couple to the fermions. The Yukawa Lagrangian takes the form

Y=\displaystyle\mathcal{L}_{Y}= h33JQ¯3LχJ3R+hαβJQ¯αLχJβR+h3auQ¯3LηuaR+hαauΛQ¯αLηχuaR+hαadQ¯αLηdaR\displaystyle h^{J}_{33}\bar{Q}_{3L}\chi J_{3R}+h^{J}_{\alpha\beta}\bar{Q}_{\alpha L}\chi^{*}J_{\beta R}+h^{u}_{3a}\bar{Q}_{3L}\eta u_{aR}+\frac{h^{u}_{\alpha a}}{\Lambda}\bar{Q}_{\alpha L}\eta\chi u_{aR}+h^{d}_{\alpha a}\bar{Q}_{\alpha L}\eta^{*}d_{aR}
+\displaystyle+ h3adΛQ¯3LηχdaR+habeψ¯aLcψbLη+habeΛ2(ψ¯aLcηχ)(ψbLχ)+sabνΛ(ψ¯aLcη)(ψbLη)+h.c.,\displaystyle\frac{h^{d}_{3a}}{\Lambda}\bar{Q}_{3L}\eta^{*}\chi^{*}d_{aR}+h^{e}_{ab}\bar{\psi}^{c}_{aL}\psi_{bL}\eta+\frac{h^{\prime e}_{ab}}{\Lambda^{2}}(\bar{\psi}^{c}_{aL}\eta\chi)(\psi_{bL}\chi^{*})+\frac{s^{\nu}_{ab}}{\Lambda}(\bar{\psi}^{c}_{aL}\eta^{*})(\psi_{bL}\eta^{*})+h.c., (20)

where Λ\Lambda is the scale of new physics, which has a mass dimension that defines the effective interactions and needs to yield masses for all the fermions m331 . Upon the above interactions, the top quark and new quarks obtain masses via renormalization gauge invariant operators while the remaining quarks get masses via non-renormalization gauge invariant operators of dimension d>4d>4. After gauge symmetry breaking, a few gauge bosons have mass m331 . The physical charged gauge bosons with masses are, respectively, given by

W±A1iA22,mW2=g24u2,\displaystyle W^{\pm}\equiv\frac{A_{1}\mp iA_{2}}{\sqrt{2}},\hskip 14.22636ptm^{2}_{W}=\frac{g^{2}}{4}u^{2}, (21)
XA4iA52,mX2=g24(w2+u2),\displaystyle X^{\mp}\equiv\frac{A_{4}\mp iA_{5}}{\sqrt{2}},\hskip 14.22636ptm^{2}_{X}=\frac{g^{2}}{4}(w^{2}+u^{2}), (22)
YA6iA72,mY2=g24w2.\displaystyle Y^{\mp\mp}\equiv\frac{A_{6}\mp iA_{7}}{\sqrt{2}},\hskip 14.22636ptm^{2}_{Y}=\frac{g^{2}}{4}w^{2}. (23)

The neutral gauge bosons with corresponding masses are given as follows

Aμ\displaystyle A_{\mu} =sWA3μ+cW(3tWA8μ+13tW2Bμ),mA=0,\displaystyle=s_{W}A_{3\mu}+c_{W}\left(-\sqrt{3}t_{W}A_{8\mu}+\sqrt{1-3t^{2}_{W}}B_{\mu}\right),\hskip 14.22636ptm_{A}=0, (24)
Zμ\displaystyle Z_{\mu} =cWA3μsW(3tWA8μ+13tW2Bμ),mZ2=g24cW2u2,\displaystyle=c_{W}A_{3\mu}-s_{W}\left(-\sqrt{3}t_{W}A_{8\mu}+\sqrt{1-3t^{2}_{W}}B_{\mu}\right),\hskip 14.22636ptm_{Z}^{2}=\frac{g^{2}}{4c_{W}^{2}}u^{2}, (25)
Zμ\displaystyle Z^{\prime}_{\mu} =13tW2A8μ+3tWBμ,mZ2=g2[(14sW2)2u2+4cW4w2]12cW2(14sW2),\displaystyle=\sqrt{1-3t^{2}_{W}}A_{8\mu}+\sqrt{3}t_{W}B_{\mu},\hskip 14.22636ptm^{2}_{Z^{\prime}}=\frac{g^{2}\left[(1-4s_{W}^{2})^{2}u^{2}+4c_{W}^{4}w^{2}\right]}{12c_{W}^{2}(1-4s_{W}^{2})}, (26)

where sinθWsW=e/g=t/1+4t2\sin\theta_{W}\equiv s_{W}=e/g=t/\sqrt{1+4t^{2}}, with t=gX/gt=g_{X}/g.

III Higgs lepton flavor violating decay

III.1 hh\rightarrow μτ\mu\tau

Let us consider a non-zero rate for a lepton flavor-violating decay mode of the Higg decay. This phenomenology is directly related to the leptonic part of Eq. (20). In the physical basis for the scalar, this part can be rewritten as follows:

Y\displaystyle\mathcal{L}_{Y}\supset e¯aR(cζ1u(e)absζhabe2uwΛ2)ebLhe¯aR(sζ1u(e)ab+cζhabe2uwΛ2)ebLH\displaystyle-\bar{e}_{aR}\left(c_{\zeta}\frac{1}{u}\left(\mathcal{M}_{e}\right)_{ab}-s_{\zeta}\frac{h^{\prime e}_{ab}}{\sqrt{2}}\frac{uw}{\Lambda^{2}}\right)e_{bL}h-\bar{e}_{aR}\left(s_{\zeta}\frac{1}{u}\left(\mathcal{M}_{e}\right)_{ab}+c_{\zeta}\frac{h^{\prime e}_{ab}}{\sqrt{2}}\frac{uw}{\Lambda^{2}}\right)e_{bL}H (27)
(eaL)c¯(cθhabe+sθhabeuw2Λ2)νbLH++(νaL)c¯(cθhabe)ebLH+\displaystyle-\bar{(e_{aL})^{c}}\left(c_{\theta}h_{ab}^{e}+s_{\theta}h^{\prime e}_{ab}\frac{uw}{2\Lambda^{2}}\right)\nu_{bL}H^{+}+\bar{(\nu_{aL})^{c}}\left(c_{\theta}h_{ab}^{e}\right)e_{bL}H^{+}
+sabνΛu2cθ(νaL¯ebR+(eaR)c¯(νbL)c)H++h.c.,\displaystyle+\frac{s^{\nu{\dagger}}_{ab}}{\Lambda}\frac{u}{\sqrt{2}}c_{\theta}\left(\bar{\nu_{aL}}e_{bR}+\bar{(e_{aR})^{c}}(\nu_{bL})^{c}\right)H^{+}+h.c.,

where (e)ab=2u(habe+habew24Λ2)\left(\mathcal{M}_{e}\right)_{ab}=\sqrt{2}u\left(h_{ab}^{e}+\frac{h^{\prime e}_{ab}w^{2}}{4\Lambda^{2}}\right) is a mixing mass of charged leptons. We denote eL,R=(e,μ,τ)L,R=(UL,Re)1(e1,e2,e3)L,Re^{\prime}_{L,R}=\left(e,\mu,\tau\right)_{L,R}=(U^{e}_{L,R})^{-1}\left(e_{1},e_{2},e_{3}\right)_{L,R}, νL=(νe,νμ,ντ)L=(VLν)1(ν1,ν2,ν3)L\nu_{L}^{\prime}=\left(\nu_{e},\nu_{\mu},\nu_{\tau}\right)_{L}=(V^{\nu}_{L})^{-1}\left(\nu_{1},\nu_{2},\nu_{3}\right)_{L}, the Lagrangian given in (27) can be rewritten as

Y\displaystyle\mathcal{L}_{Y}\supset e¯RgheeeLh+e¯RgHeeeLH\displaystyle\bar{e}^{\prime}_{R}g_{h}^{ee}e^{\prime}_{L}h+\bar{e}^{\prime}_{R}g_{H}^{ee}e^{\prime}_{L}H (28)
+{(eL)c¯gLeννL+(νL)c¯gLνeeL+ν¯LgRνeeR+(eR)c¯gReν(νL)c}H++h.c.,\displaystyle+\left\{\bar{(e^{\prime}_{L})^{c}}g_{L}^{e\nu}\nu^{\prime}_{L}+\bar{(\nu^{\prime}_{L})^{c}}g_{L}^{\nu e}e^{\prime}_{L}+\bar{\nu^{\prime}}_{L}g_{R}^{\nu e}e^{\prime}_{R}+\bar{(e^{\prime}_{R})^{c}}g_{R}^{e\nu}(\nu^{\prime}_{L})^{c}\right\}H^{+}+h.c.,

where ghee=URe(cζ1uesζuw2Λ2he)ULeg_{h}^{ee}=U_{R}^{e{\dagger}}\left(c_{\zeta}\frac{1}{u}\mathcal{M}_{e}-s_{\zeta}\frac{uw}{\sqrt{2}\Lambda^{2}}h^{\prime e}\right)U^{e}_{L}, gHee=URe(sζ1ue+cζuw2Λ2he)ULeg_{H}^{ee}=U_{R}^{e{\dagger}}\left(s_{\zeta}\frac{1}{u}\mathcal{M}_{e}+c_{\zeta}\frac{uw}{\sqrt{2}\Lambda^{2}}h^{\prime e}\right)U^{e}_{L}, gLeν=(ULe)T(cθhe+sθuw2Λ2he)ULνg_{L}^{e\nu}=(U_{L}^{e})^{T}\left(c_{\theta}h^{e}+s_{\theta}\frac{uw}{2\Lambda^{2}}h^{e\prime}\right)U_{L}^{\nu}, gLνe=(ULν)TcθheULeg_{L}^{\nu e}=(U_{L}^{\nu})^{T}c_{\theta}h^{e}U^{e}_{L}, gRνe=ULνcθu2ΛsνUReg_{R}^{\nu e}=U_{L}^{\nu{\dagger}}c_{\theta}\frac{u}{\sqrt{2}\Lambda}s^{\nu}U^{e}_{R}, gReν=ULeTcθu2ΛsνURνTg_{R}^{e\nu}=U_{L}^{eT}c_{\theta}\frac{u}{\sqrt{2}\Lambda}s^{\nu}U^{\nu T}_{R}.

In every parenthesis in the line of Eq. (27), the first term is proportional to the charged lepton masses, whereas the second term in general can contain off-diagonal entries. It is the source of the HLFV processes and leads to the heiejh\rightarrow e_{i}e_{j} decays, with iji\neq j. The branching for this decay process can be written as follows:

Br(heiej)=mh8πΓh(|gheiej|2+|ghejei|2),\displaystyle\text{Br}(h\rightarrow e_{i}e_{j})=\frac{m_{h}}{8\pi\Gamma_{h}}\left(|g_{h}^{e_{i}e_{j}}|^{2}+|g_{h}^{e_{j}e_{i}}|^{2}\right), (29)

where Γh4MeV\Gamma_{h}\simeq 4\ \text{MeV} is the total Higgs boson hh decay width, gheiejg_{h}^{e_{i}e_{j}} is the Higgs boson hh coupling to the charged leptons that we can be obtained from Eq.(28). This coupling not only depends on the VEVs and the energy scale Λ\Lambda but also on the Higgs couplings λ2,λ3\lambda_{2},\lambda_{3}.

Refer to captionRefer to caption
Figure 1: The branching ratio Br(hμτ)(h\rightarrow\mu\tau) as a function of factor λ3λ2\frac{\lambda_{3}}{\lambda_{2}} for different choice of energy scale Λ\Lambda. The left and right panels are studied by fixing [(URe)heULe]μτ=2mμmτu\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=2\frac{\sqrt{m_{\mu}m_{\tau}}}{u} according to the Cheng–Sher ansatz Cheng-Sher and [(URe)heULe]μτ=5×104\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=5\times 10^{-4}, respectively

The numerical result is shown in Fig.1 for fixing u=246GeV,w=Λu=246\ \text{GeV},w=\Lambda. It is easy to see that the branching ratio of the hμτh\rightarrow\mu\tau can reach the experimental 95%95\% C.L. upper bounds on the HLFV branching ratios from the CMS Collaborations and also can be as low as 10810^{-8}. It depends quite strongly on the factor λ3λ2\frac{\lambda_{3}}{\lambda_{2}}, heh^{\prime e}, and on the energy scale Λ\Lambda. In the small Λ\Lambda region and for the factor λ3λ2>1\frac{\lambda_{3}}{\lambda_{2}}>1, the branching ratio for hμτh\rightarrow\mu\tau can reach 10310^{-3}. However, in this region, the mixing angle of ξ\xi is large. Thus, the simple 3-3-1 model may face stringent constraints such as the Higgs boson couplings to fermions and gauge bosons. If Λ\Lambda is taken to be a few TeV but below the Landau pole, λ1,λ2\lambda_{1},\lambda_{2} are of the same order, the mixing angle ξ\xi is small and the branching ratio for hμτh\rightarrow\mu\tau reaches 10510^{-5}.

III.2 τμγ\tau\rightarrow\mu\gamma

We would like to note that the interaction terms which are given in (28) including the lepton flavor-violating and -conserving couplings can affect other LFV processes such as eiejγe_{i}\rightarrow e_{j}\gamma. Besides this contribution, the charged current interactions also induce LFV processes. In the simple 3-3-1 model, the charged current interactions have the following form:

g2(ν¯aLγμeaLWμ++ν¯aLγμeaRcXμ++e¯aLγμeaRcYμ)+h.c..\displaystyle-\frac{g}{\sqrt{2}}\left(\bar{\nu}_{aL}\gamma^{\mu}e_{aL}W^{+}_{\mu}+\bar{\nu}_{aL}\gamma^{\mu}e_{aR}^{c}X_{\mu}^{+}+\bar{e}_{aL}\gamma^{\mu}e_{aR}^{c}Y^{--}_{\mu}\right)+h.c.. (30)

Taking all these ingredients into account, the total contribution to the τμγ\tau\rightarrow\mu\gamma decay include:

  • the one-loop diagram with singly charged gauge bosons and neutrinos in the loop

  • the one-loop diagram with doubly charged gauge bosons and charged leptons in the loop

  • the one-loop diagram with charged Higgs bosons and neutrinos in the loop

  • the one-loop diagram with neutral Higgs bosons and charged leptons in the loop

  • two-loop Barr-Zee diagrams with an internal photon and a third generation quark

  • two-loop Barr-Zee diagrams with an internal photon and a gauge boson

The first three types of contributions are the same as those of the 3-3-1 model with a new lepton; see HueLFV . The last three types of contributions come from the source of the HLFV processes that are a new contribution and have been not considered in the previous version of the 3-3-1 model HueLFV . The total effective Lagrangian describing the eiejγe_{i}\rightarrow e_{j}\gamma decay process is given as

emτ{e¯i(DRγ)ijσαβPRejFαβ+e¯i(DLγ)ijσαβPLejFαβ}.\displaystyle em_{\tau}\left\{\bar{e^{\prime}}_{i}\left(D_{R}^{\gamma}\right)_{ij}\sigma^{\alpha\beta}P_{R}e_{j}^{\prime}F_{\alpha\beta}+\bar{e^{\prime}}_{i}\left(D_{L}^{\gamma}\right)_{ij}\sigma^{\alpha\beta}P_{L}e_{j}^{\prime}F_{\alpha\beta}\right\}. (31)

It leads to the branching ratio of the τμγ\tau\rightarrow\mu\gamma following processes:

Br(τμγ)=\displaystyle\text{Br}(\tau\rightarrow\mu\gamma)= 48π3αGF2(|DLγ|2+|DRγ|2)Br(τμν¯μντ),\displaystyle{}\frac{48\pi^{3}\alpha}{G_{F}^{2}}\left(|D_{L}^{\gamma}|^{2}+|D_{R}^{\gamma}|^{2}\right)Br(\tau\rightarrow\mu\bar{\nu}_{\mu}\nu_{\tau}), (32)

where DL,RγD_{L,R}^{\gamma} comes from the one-loop and two-loop diagrams. Firstly, the one-loop diagram contributions with charged Higgs boson H±H^{\pm}, charged gauge boson W±W^{\pm} and doubly charged gauge boson Y±±Y^{\pm\pm} have a form inspired by the general formula in Lavoura :

D1RνW±=eg2mτ32π2mW2j=13Uj3νUj2νf(mνj2mW2),D1LνW±=eg2mμ32π2mW2j=13Uj3νUj2νf(mνj2mW2),\displaystyle D_{1R}^{\nu W^{\pm}}=-\frac{eg^{2}m_{\tau}}{32\pi^{2}m_{W}^{2}}\sum_{j=1}^{3}U^{\nu}_{j3}U^{\nu*}_{j2}f\left(\frac{m_{\nu_{j}}^{2}}{m_{W}^{2}}\right),\hskip 14.22636ptD_{1L}^{\nu W^{\pm}}=-\frac{eg^{2}m_{\mu}}{32\pi^{2}m_{W}^{2}}\sum_{j=1}^{3}U^{\nu}_{j3}U^{\nu*}_{j2}f\left(\frac{m_{\nu_{j}}^{2}}{m_{W}^{2}}\right),
D1RνX±=eg2mτ32π2mX2j=13Uj3νUj2νf(mνj2mX2),D1LνX±=eg2mμ32π2mX2j=13Uj3νUj2νf(mνj2mX2),\displaystyle D_{1R}^{\nu X^{\pm}}=-\frac{eg^{2}m_{\tau}}{32\pi^{2}m_{X}^{2}}\sum_{j=1}^{3}U^{\nu}_{j3}U^{\nu*}_{j2}f\left(\frac{m_{\nu_{j}}^{2}}{m_{X}^{2}}\right),\hskip 14.22636ptD_{1L}^{\nu X^{\pm}}=-\frac{eg^{2}m_{\mu}}{32\pi^{2}m_{X}^{2}}\sum_{j=1}^{3}U^{\nu}_{j3}U^{\nu*}_{j2}f\left(\frac{m_{\nu_{j}}^{2}}{m_{X}^{2}}\right),
D1ReY±±=eg2mτ32π2mY±±2j=13[g(mej2mY±±2)2f(mej2mY±±2)],\displaystyle D_{1R}^{eY^{\pm\pm}}=-\frac{eg^{2}m_{\tau}}{32\pi^{2}m_{Y^{\pm\pm}}^{2}}\sum_{j=1}^{3}\left[g\left(\frac{m_{e_{j}}^{2}}{m_{Y^{\pm\pm}}^{2}}\right)-2f\left(\frac{m_{e_{j}}^{2}}{m_{Y^{\pm\pm}}^{2}}\right)\right],
D1LeY±±=eg2mμ32π2mY±±2j=13[g(mej2mY±±2)2f(mej2mY±±2)],\displaystyle D_{1L}^{eY^{\pm\pm}}=-\frac{eg^{2}m_{\mu}}{32\pi^{2}m_{Y^{\pm\pm}}^{2}}\sum_{j=1}^{3}\left[g\left(\frac{m_{e_{j}}^{2}}{m_{Y^{\pm\pm}}^{2}}\right)-2f\left(\frac{m_{e_{j}}^{2}}{m_{Y^{\pm\pm}}^{2}}\right)\right],
D1RνH±=eg232π2mH±2mW2j=13{gLντgLνμmτh(mνj2mH±2)\displaystyle D_{1R}^{\nu H^{\pm}}=-\frac{eg^{2}}{32\pi^{2}m_{H^{\pm}}^{2}m_{W}^{2}}\sum_{j=1}^{3}\left\{g^{\nu\tau*}_{L}g^{\nu\mu}_{L}m_{\tau}h\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)\right.
+gRντgRνμmμk(mνj2mH±2)+gLντgRνμmHr(mνj2mH±2)},\displaystyle\left.\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt+g^{\nu\tau*}_{R}g^{\nu\mu}_{R}m_{\mu}k\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)+g^{\nu\tau*}_{L}g^{\nu\mu}_{R}m_{H}r\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)\right\},
D1LνH±=eg232π2mH±2mW2j=13{gRντgRνμmτh(mνj2mH±2)\displaystyle D_{1L}^{\nu H^{\pm}}=-\frac{eg^{2}}{32\pi^{2}m_{H^{\pm}}^{2}m_{W}^{2}}\sum_{j=1}^{3}\left\{g^{\nu\tau*}_{R}g^{\nu\mu}_{R}m_{\tau}h\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)\right.
+gLντgLνμmμk(mνj2mH±2)+gRντgLνμmHr(mνj2mH±2)}.\displaystyle\left.\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt\hskip 14.22636pt+g^{\nu\tau*}_{L}g^{\nu\mu}_{L}m_{\mu}k\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)+g^{\nu\tau*}_{R}g^{\nu\mu}_{L}m_{H}r\left(\frac{m_{\nu_{j}}^{2}}{m_{H^{\pm}}^{2}}\right)\right\}.

with the functions f,g,h,kf,g,h,k and rr defined by

f(x)\displaystyle f(x) =\displaystyle= 1043x+78x249x3+4x4+18x3lnx12(x1)4,\displaystyle\frac{10-43x+78x^{2}-49x^{3}+4x^{4}+18x^{3}\ln{x}}{12(x-1)^{4}},
g(x)\displaystyle g(x) =\displaystyle= 838x+39x214x3+5x418x2lnx12(x1)4,\displaystyle\frac{8-38x+39x^{2}-14x^{3}+5x^{4}-18x^{2}\ln{x}}{12(x-1)^{4}},
h(x)\displaystyle h(x) =\displaystyle= k(x)=16x+3x2+2x36x2lnx12(x1)4,\displaystyle k(x)=\frac{1-6x+3x^{2}+2x^{3}-6x^{2}\ln{x}}{12(x-1)^{4}},
r(x)\displaystyle r(x) =\displaystyle= 1+x22xlnx2(x1)3.\displaystyle\frac{-1+x^{2}-2x\ln{x}}{2(x-1)^{3}}. (34)

The neutral Higgs contribution to DL,RγD_{L,R}^{\gamma} via the one-loop diagram is

D1Lγ=D1Rγ=2ϕgϕμτgϕττmϕ2(lnmϕ2mτ232),\displaystyle D_{1L}^{\gamma}=D_{1R}^{\gamma}=\sqrt{2}\sum_{\phi}\frac{g_{\phi}^{\mu\tau}g_{\phi}^{\tau\tau}}{m_{\phi}^{2}}\left(\ln\frac{m_{\phi}^{2}}{m_{\tau}^{2}}-\frac{3}{2}\right), (35)

and the two-loop correction to DLRγD^{\gamma}_{LR} being given by Sacha

D2Lγ=D2Rγ=2ϕ,fgϕμτgϕffNcQf2απ1mτmffϕ(mf2mϕ2)\displaystyle D_{2L}^{\gamma}=D^{\gamma}_{2R}=2\sum_{\phi,f}g_{\phi}^{\mu\tau}g_{\phi}^{ff}\frac{N_{c}Q_{f}^{2}\alpha}{\pi}\frac{1}{m_{\tau}m_{f}}f_{\phi}\left(\frac{m_{f}^{2}}{m_{\phi}^{2}}\right)
ϕ=h,HgϕμτgϕGGαQG22πmτmG2{3fϕ(mG2mϕ2)+234g(mG2mϕ2)+34h(mG2mϕ2)+mϕ2fϕ(mG2mϕ2)g(mG2mϕ2)2mG2},\displaystyle-\sum_{\phi=h,H}g_{\phi}^{\mu\tau}g_{\phi}^{GG}\frac{\alpha Q_{G}^{2}}{2\pi m_{\tau}m_{G}^{2}}\left\{3f_{\phi}\left(\frac{m_{G}^{2}}{m^{2}_{\phi}}\right)+\frac{23}{4}g\left(\frac{m_{G}^{2}}{m^{2}_{\phi}}\right)+\frac{3}{4}h\left(\frac{m_{G}^{2}}{m_{\phi}^{2}}\right)+m_{\phi}^{2}\frac{f_{\phi}\left(\frac{m_{G}^{2}}{m_{\phi}^{2}}\right)-g\left(\frac{m_{G}^{2}}{m_{\phi}^{2}}\right)}{2m_{G}^{2}}\right\},

where Φ=h,H\Phi=h,H, G=W±,X±,Y±±G=W^{\pm},X^{\pm},Y^{\pm\pm}, f=t,bf=t,b, and QGQ_{G} is an electrical charge of the gauge boson GG. gϕμτ,gϕff,gϕGGg_{\phi}^{\mu\tau},g_{\phi}^{ff},g_{\phi}^{GG} are the scalar ϕ\phi couplings to μ\mu τ\tau, two fermions, and two gauge bosons GG, respectively. The expressions for gϕff,gϕGGg_{\phi}^{ff},g_{\phi}^{GG} are given in m331 and for gϕμτg_{\phi}^{\mu\tau} can be obtained from Eq.(28). The loop functions, fϕ(z),h(z),g(z)f_{\phi}(z),h(z),g(z), are given by Sacha

fh,H(z)\displaystyle f_{h,H}(z) =z201𝑑x(12x(1x))x(1x)zlnx(1x)z,\displaystyle=\frac{z}{2}\int_{0}^{1}dx\frac{\left(1-2x(1-x)\right)}{x(1-x)-z}\ln\frac{x(1-x)}{z},
h(z)\displaystyle h(z) =z201dxx(1x)z{1zx(1x)zlnx(1x)z}\displaystyle=-\frac{z}{2}\int_{0}^{1}\frac{dx}{x(1-x)-z}\left\{1-\frac{z}{x(1-x)-z}\ln\frac{x(1-x)}{z}\right\}
g(z)\displaystyle g(z) =z201𝑑x1x(1x)zlnx(1x)z.\displaystyle=\frac{z}{2}\int^{1}_{0}dx\frac{1}{x(1-x)-z}\ln\frac{x(1-x)}{z}. (36)

In the limits z1z\gg 1 and z1z\ll 1, the functions f(z),g(z)f(z),g(z) and h(z)h(z) can approximately be written as follow:

z1,f(z)=z2(lnz)2,g(z))=z2(lnz)2,h(z)=zlnz,\displaystyle z\ll 1,\hskip 14.22636ptf(z)=\frac{z}{2}(\ln{z})^{2},\hskip 14.22636ptg(z))=\frac{z}{2}(\ln{z})^{2},\hskip 14.22636pth(z)=z\ln{z},
z1,f(z)=lnz3+1318,g(z)=lnz2+1,h(z)=lnz212.\displaystyle z\gg 1,\hskip 14.22636ptf(z)=\frac{\ln{z}}{3}+\frac{13}{18},\hskip 14.22636ptg(z)=\frac{\ln{z}}{2}+1,\hskip 14.22636pth(z)=-\frac{\ln{z}}{2}-\frac{1}{2}. (37)

For z𝒪(1)z\sim\mathcal{O}(1), the functions f,g,hzf,g,h\sim z can be accurately calculated. Let us estimate each kind of diagrams contributing to τμγ\tau\rightarrow\mu\gamma via numerical studies. We choose the parameters as follows:

mW=80.385GeV,me=0.000511GeV,mμ=0.1056GeV,mτ=1.176GeV\displaystyle\hskip 14.22636ptm_{W}=80.385\ \text{GeV},\hskip 14.22636ptm_{e}=0.000511\ \text{GeV},\hskip 14.22636ptm_{\mu}=0.1056\ \text{GeV},\hskip 14.22636ptm_{\tau}=1.176\ \text{GeV}
sin2(θ12)=0.307,sin2(θ23)=0.51,sin2(θ13)=0.021,α=1137,u=246GeV\displaystyle\sin^{2}(\theta_{12})=0.307,\hskip 14.22636pt\sin^{2}(\theta_{23})=0.51,\hskip 14.22636pt\sin^{2}(\theta_{13})=0.021,\hskip 14.22636pt\alpha=\frac{1}{137},\hskip 14.22636ptu=246\ \text{GeV}
Δm122=mν22mν12=7.53×105eV2,Δm232=mν32mν22=2.45×103eV2\displaystyle\Delta m_{12}^{2}=m_{\nu_{2}}^{2}-m_{\nu_{1}}^{2}=7.53\times 10^{-5}\ \text{eV}^{2},\hskip 14.22636pt\Delta m_{23}^{2}=m_{\nu_{3}}^{2}-m_{\nu_{2}}^{2}=2.45\times 10^{-3}\ \text{eV}^{2}
λ2=λ1=0.09,sν1010.\displaystyle\lambda_{2}=\lambda_{1}=0.09,\hskip 14.22636pts^{\nu}\sim 10^{-10}. (38)
Refer to captionRefer to caption
Figure 2: The dependence of branching ratio Br(τμγ)(\tau\rightarrow\mu\gamma) on the scale of new physics Λ\Lambda in 1-loop, 1-loop with new neutral Higgs boson HH, 2-loop and total contribution, respectively. The green solid line is the experimental constraint Br(τμγ)Exp<4.4×108(\tau\rightarrow\mu\gamma)_{\text{Exp}}<4.4\times 10^{-8}. We fix [(URe)heULe]μτ=2mμmτu\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=2\frac{\sqrt{m_{\mu}m_{\tau}}}{u} and [(URe)heULe]μτ=5×104\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=5\times 10^{-4}, for left and right panels, respectively. The factor λ3λ2=1\frac{\lambda_{3}}{\lambda_{2}}=1 for both panels.

The results shown in the Fig. 2 suggest that the two-loop diagrams can provide a dominant contribution to τμγ\tau\rightarrow\mu\gamma. The Br(τμγ)(\tau\rightarrow\mu\gamma) strongly depends on the lepton flavor-violation coupling [(URe)heULe]μτ\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}. If we choose [(URe)heULe]μτ=2mμmτu\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=2\frac{\sqrt{m_{\mu}m_{\tau}}}{u}, the two-loop contribution to τμγ\tau\rightarrow\mu\gamma dominates over the one-loop contribution. However, the branch ratio, Br(τμγ)(\tau\rightarrow\mu\gamma), is only consistent with the predictions of the experiment when the new physical scale is above the Landau pole. If [(URe)heULe]μτ=5×104\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=5\times 10^{-4}, the two-loop contribution can be less important and the main contribution comes from one-loop diagrams with the conversed lepton couplings. In this case, we obtain the upper bound on the new physics scale: Λ>2.4TeV\Lambda>2.4\ \text{TeV} from the lower bound on Br(τμγ)(\tau\rightarrow\mu\gamma) of the experiment. Comparing the results given in Figs. 2 and 3, we find that the above conclusions change slightly when the factor λ3λ2\frac{\lambda_{3}}{\lambda_{2}} is changed.

Refer to captionRefer to caption
Figure 3: The dependence of branching ratio Br(τμγ)(\tau\rightarrow\mu\gamma) on the scale of new physics Λ\Lambda in one-loop, one-loop with new neutral Higgs boson HH, two-loop and total contribution, respectively. The green solid line is the experimental constraint Br(τμγ)Exp<4.4×108(\tau\rightarrow\mu\gamma)_{\text{Exp}}<4.4\times 10^{-8}. We fix [(URe)heULe]μτ=2mμmτu\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=2\frac{\sqrt{m_{\mu}m_{\tau}}}{u} by the Cheng–Sher ansatz Cheng-Sher and [(URe)heULe]μτ=5×104\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=5\times 10^{-4}, for left and right panels, respectively. The factor λ3λ2=5\frac{\lambda_{3}}{\lambda_{2}}=5 for both panels.

III.3 (g2)μ\left(g-2\right)_{\mu}

The new physics of the 3-3-1 model contributes to the muon’s anomalous magnetic moments aμa_{\mu} via the flavor conserving couplings was considered by BHHL ; QRmuon . The 3-3-1 model also has FCNC, so it can make its own contribution to the anomalous magnetic moment. First, we investigate only the contribution of the FCNC to (g2)μ(g-2)_{\mu}. There exists a one-loop contribution to (g2)μ(g-2)_{\mu} through flavor-violating couplings of the Higgs to μτ\mu\tau. According to the work given in Sacha , the one-loop contribution mediated by the neutral Higgs contribution to (g2)μ\left(g-2\right)_{\mu} can be expressed by

(Δaμ)M331\displaystyle(\Delta a_{\mu})^{M331} =ϕ(gϕτμ)2mμmτ8π208𝑑xx2mϕ2x(mϕ2mτ2)\displaystyle=\sum_{\phi}\left(g_{\phi}^{\tau\mu}\right)^{2}\frac{m_{\mu}m_{\tau}}{8\pi^{2}}\int_{0}^{8}dx\frac{x^{2}}{m_{\phi}^{2}-x(m_{\phi}^{2}-m_{\tau}^{2})} (39)
ϕ(gϕτμ)2mμmτ8π2mϕ2(lnmϕ2mτ232).\displaystyle\simeq\sum_{\phi}\left(g_{\phi}^{\tau\mu}\right)^{2}\frac{m_{\mu}m_{\tau}}{8\pi^{2}m_{\phi}^{2}}\left(\ln\frac{m_{\phi}^{2}}{m_{\tau}^{2}}-\frac{3}{2}\right).
Refer to caption
Figure 4: Contribution of the HLFV interactions to ΔaμM331\Delta a_{\mu}^{M331} as a function of self Higgs coupling λ2\lambda_{2} for different factors of λ3λ2\frac{\lambda_{3}}{\lambda_{2}} and fixing Λ=2000GeV\Lambda=2000\ \text{GeV}.

We plot in Fig. 4 the muon’s anomalous magnetic moment ΔaμM331\Delta a_{\mu}^{M331} as a function of the self-Higgs coupling λ2\lambda_{2}, assuming Λ=2000\Lambda=2000 GeV, [(URe)heULe]μτ=2mμmτu,w=Λ,u=246\left[(U^{e}_{R})^{\dagger}h^{\prime e}U_{L}^{e}\right]_{\mu\tau}=2\frac{\sqrt{m_{\mu}m_{\tau}}}{u},w=\Lambda,u=246 GeV. This choice leads to the branching ratio hτμh\rightarrow\tau\mu and can be close to the upper limit value of the experiment or as low as 10510^{-5} but the flavor-changing interactions of neutral Higgs and two leptons contributed negligibly to ΔaμM331\Delta a_{\mu}^{M331}; see Fig. 4. We would like to emphasize that the new contribution to the muon magnetic moment (g2)μ(g-2)_{\mu} in the context of the simple 3-3-1 model comes from the doubly gauge bosons Y±±Y^{\pm\pm}, new singly charged vectors V±V^{\pm}, and new singly charged Higgs H±H^{\pm}. The dominant contribution is the doubly charged gauge boson running in the loop QRmuon . The total doubly charged boson contribution is given by

Δaμ(X±±)283mμ2u2+w2.\displaystyle\Delta a_{\mu}(X^{\pm\pm})\simeq\frac{28}{3}\frac{m_{\mu}^{2}}{u^{2}+w^{2}}. (40)

It is easy to check that an energy scale of symmetry breaking SU(3)LSU(3)_{L} around 2 TeV, 1.7 TeV <w<<w<2.2 TeV, is favored as regards explaining the discrepancy of the measured value of muon’s anomalous magnetic moment and the one predicted by the standard model muon ,

(Δaμ)EXPSM=(26.1±8)×1010.\displaystyle(\Delta a_{\mu})_{EXP-SM}=(26.1\pm 8)\times 10^{-10}. (41)

As mentioned in m331 , the LHC constraint over the ZZ^{\prime} mass in the simple 3-3-1 model is MZ>2.75M_{Z}^{\prime}>2.75 TeV. It can be translated into the lower bound on the VEV, ww, as follows: w>2.38w>2.38 TeV. Therefore, the parameter space of w, which is favored for explaining (Δaμ)EXPSM(\Delta a_{\mu})_{EXP-SM}, is slightly smaller than the lower limit of the LHC (very close to the LHC’s allowed space). In other words, in the parameter space that allows an interpretation to be made of LHC’s experimental results, the value of the muon’s anomalous magnetic moment is predicted, (Δaμ)331<13.8×1010(\Delta a_{\mu})_{331}<13.8\times 10^{-10}. The upper limit is very close to the constraint given in Eq. (41).

IV Quark flavor-violating Higgs boson decay

We would like to note that the third family of quarks is transformed differently from the first two families under transformation; it causes the FCNC at the tree level. This works is in m331 ; the authors studied the tree-level FCNCs due to the new neutral gauge boson exchange. However, the FCNC is not only caused by the new neutral gauge boson (ZZ^{\prime}) exchange but also caused by the SM Higgs boson and a new Higgs boson. After electroweak symmetry breaking, the operators of Eq.(20) give rise to the interaction of neutral Higgs bosons with a pair of SM quark of the form

Y\displaystyle\mathcal{L}_{Y} u¯aR{cξ1u(Mu)ab+sξhabuΛu2}ubLhu¯aR{sξ1u(Mu)abcξhabuΛu2}ubLH\displaystyle\supset-\bar{u}_{aR}\left\{c_{\xi}\frac{1}{u}\left(M^{u}\right)_{ab}+s_{\xi}\frac{h_{ab}^{u}}{\Lambda}\frac{u}{2}\right\}u_{bL}h-\bar{u}_{aR}\left\{s_{\xi}\frac{1}{u}\left(M^{u}\right)_{ab}-c_{\xi}\frac{h_{ab}^{u}}{\Lambda}\frac{u}{2}\right\}u_{bL}H (42)
d¯aR{cξ1u(Md)absξhabdΛu2}dbLd¯aR{sξ1u(Md)ab+cξhabdΛu2}dbLH+h.c.,\displaystyle-\bar{d}_{aR}\left\{c_{\xi}\frac{1}{u}\left(M^{d}\right)_{ab}-s_{\xi}\frac{h_{ab}^{d}}{\Lambda}\frac{u}{2}\right\}d_{bL}-\bar{d}_{aR}\left\{s_{\xi}\frac{1}{u}\left(M^{d}\right)_{ab}+c_{\xi}\frac{h_{ab}^{d}}{\Lambda}\frac{u}{2}\right\}d_{bL}H+h.c.,

where habu=0h^{u}_{ab}=0 if a=3a=3, habd=0h^{d}_{ab}=0 if a=1,2a=1,2 and the remaining values of habu,habdh_{ab}^{u},h_{ab}^{d} are nonzero. We define the physical sates uL,R=(u1L,R,u2L,R,u3L,R)Tu_{L,R}^{\prime}=(u_{1L,R}^{\prime},u_{2L,R}^{\prime},u_{3L,R}^{\prime})^{T}, dL,R=(d1L,R,d2L,R,d3L,R)Td_{L,R}^{\prime}=(d_{1L,R}^{\prime},d_{2L,R}^{\prime},d_{3L,R}^{\prime})^{T}. They are related to the flavor states u=(u1L,R,u2L,R,u3L,R)T,d=(d1LR,d2LR,d3L,R)Tu=(u_{1L,R},u_{2L,R},u_{3L,R})^{T},d=(d_{1LR},d_{2LR},d_{3L,R})^{T} by VL,Ru,dV_{L,R}^{u,d} matrices by uL,R=VL,RuuL,R,dL,R=VL,RddL,Ru_{L,R}=V_{L,R}^{u}u_{L,R}^{\prime},d_{L,R}=V_{L,R}^{d}d_{L,R}^{\prime}. In the physical states, the Lagrangian given in Eq.(42) can be rewritten as follows:

Y\displaystyle\mathcal{L}_{Y} u¯R𝒢huuLh+d¯R𝒢hddLh+u¯R𝒢HuuLH+d¯L𝒢HddRH+h.c.,\displaystyle\supset\bar{u^{\prime}}_{R}\mathcal{G}_{h}^{u}u^{\prime}_{L}h+\bar{d^{\prime}}_{R}\mathcal{G}_{h}^{d}d^{\prime}_{L}h+\bar{u^{\prime}}_{R}\mathcal{G}_{H}^{u}u^{\prime}_{L}H+\bar{d^{\prime}}_{L}\mathcal{G}^{d}_{H}d^{\prime}_{R}H+h.c., (43)

where 𝒢hu=(VRu){cξ1uMu+sξhuΛu2}VLu\mathcal{G}^{u}_{h}=-\left(V^{u}_{R}\right)^{\dagger}\left\{c_{\xi}\frac{1}{u}M^{u}+s_{\xi}\frac{h^{u}}{\Lambda}\frac{u}{2}\right\}V^{u}_{L}, 𝒢hd=(VRd){cξ1uMdsξhdΛu2}VLd\mathcal{G}^{d}_{h}=-\left(V^{d}_{R}\right)^{\dagger}\left\{c_{\xi}\frac{1}{u}M^{d}-s_{\xi}\frac{h^{d}}{\Lambda}\frac{u}{2}\right\}V^{d}_{L}, 𝒢Hu=(VRu){sξ1uMucξhuΛu2}VLu\mathcal{G}^{u}_{H}=-\left(V^{u}_{R}\right)^{\dagger}\left\{s_{\xi}\frac{1}{u}M^{u}-c_{\xi}\frac{h^{u}}{\Lambda}\frac{u}{2}\right\}V^{u}_{L}, and 𝒢Hd=(VRd){sξ1uMd+cξhdΛu2}VLd.\mathcal{G}^{d}_{H}=-\left(V^{d}_{R}\right)^{\dagger}\left\{s_{\xi}\frac{1}{u}M^{d}+c_{\xi}\frac{h^{d}}{\Lambda}\frac{u}{2}\right\}V^{d}_{L}.

Besides, the tree-level FCNC associated with the field ZμZ^{\prime}_{\mu} is given in m331 as

FCNC=g313tW2{(VqL)3i(VqL)3jq¯iLγμqjLZμ}.\displaystyle\mathcal{L}_{FCNC}=-\frac{g}{\sqrt{3}\sqrt{1-3t_{W}^{2}}}\left\{\left(V^{*}_{qL}\right)_{3i}\left(V_{qL}\right)_{3j}\bar{q}^{\prime}_{iL}\gamma^{\mu}q^{\prime}_{jL}Z^{\prime}_{\mu}\right\}. (44)

We would like to recall that the tree-level FCNC associated with the neutral gauge boson ZZ^{\prime} was considered in m331 . The strongest bound on the ZZ^{\prime} mass, mZ>4.67m_{Z^{\prime}}>4.67 TeV, came from a measurement of BsB_{s}B¯s\bar{B}_{s} oscillations. This value is close to a Landau pole. Around this point, the gauge coupling of the U(X)U(X) becomes very large and thus the theory loses the perturbative character. To avoid this difficulty, we extinguish the tree-level FCNC source caused by the new gauge boson ZZ^{\prime} in the d-quark sector by setting (VdL)3a=0\left(V_{dL}\right)_{3a}=0. Therefore, only the flavor-violating Higgs couplings to quarks can generate the FCNC at tree level, and these couplings can be constrained by K0K^{0} and Bs,d0B^{0}_{s,d} meson oscillation experiments. After integrating out the Higgs fields, the effective Lagrangian for meson mixing can be written as follows:

FCNCeff\displaystyle\mathcal{L}_{FCNC}^{eff} ={[(𝒢hq)ij]2mh2+[(𝒢Hq)ij]2mH2}(q¯iRqjL)2+{[(𝒢hq)ji]2mh2+[(𝒢Hq)ji]2mH2}(q¯iLqjR)2\displaystyle=\left\{\frac{\left[\left(\mathcal{G}_{h}^{q}\right)_{ij}\right]^{2}}{m_{h}^{2}}+\frac{\left[\left(\mathcal{G}_{H}^{q}\right)_{ij}\right]^{2}}{m_{H}^{2}}\right\}\left(\bar{q}_{iR}q_{jL}\right)^{2}+\left\{\frac{\left[\left(\mathcal{G}_{h}^{q}\right)_{ji}^{*}\right]^{2}}{m_{h}^{2}}+\frac{\left[\left(\mathcal{G}_{H}^{q}\right)_{ji}^{*}\right]^{2}}{m_{H}^{2}}\right\}\left(\bar{q}_{iL}q_{jR}\right)^{2} (45)
+2{[(𝒢hq)ij]mh+[(𝒢Hq)ij]mH}{[(𝒢hq)ji]mh+[(𝒢Hq)ji]mH}(q¯iRqjL)(q¯iLqjR).\displaystyle+2\left\{\frac{\left[\left(\mathcal{G}_{h}^{q}\right)_{ij}\right]}{m_{h}}+\frac{\left[\left(\mathcal{G}_{H}^{q}\right)_{ij}\right]}{m_{H}}\right\}\left\{\frac{\left[\left(\mathcal{G}_{h}^{q}\right)_{ji}^{*}\right]}{m_{h}}+\frac{\left[\left(\mathcal{G}_{H}^{q}\right)_{ji}^{*}\right]}{m_{H}}\right\}\left(\bar{q}_{iR}q_{jL}\right)\left(\bar{q}_{iL}q_{jR}\right).

The predicted results for Bd,sB_{d,s}B¯d,s\bar{B}_{d,s}, K0K^{0}K0¯\bar{K^{0}}, and D0D^{0}D¯0\bar{D}^{0} mixing are obtained as in DHLN . Note that there are two scalar fields that have flavor-violating couplings to quarks. Both of them yield the FCNC at tree level. To compare the contribution of each type, let us estimate the ratio κ[(𝒢hq)ij]2mH2([𝒢Hq)ij]2mh2mH2mh2tan2ξ\kappa\equiv\frac{\left[\left(\mathcal{G}_{h}^{q}\right)_{ij}\right]^{2}m_{H}^{2}}{\left(\left[\mathcal{G}_{H}^{q}\right)_{ij}\right]^{2}m_{h}^{2}}\simeq\frac{m_{H}^{2}}{m_{h}^{2}}\tan^{2}\xi. In the limit, w>>uw>>u, we find the value of κ\kappa to be always smaller than one unit. This means that the new scalar Higgs gives more contributions to the FCNC than the SM like Higgs boson. Fitting these results with the experimental measurements of ΔmBs,d,ΔmD,ΔmK0\Delta m_{B_{s,d}},\Delta m_{D},\Delta m_{K^{0}}, we get the bound on the flavor-violating Higgs couplings. The strongest bound for new physics comes from the BsB_{s}B¯s\bar{B}_{s} mixing. The experimental values of ΔmBs\Delta m_{B_{s}} lead to the bound on (𝒢hq)32(\mathcal{G}_{h}^{q})_{32} as follows:

2(1+1κ)|(𝒢hq)32|2=2(1+1κ)λ32u4λ22w4|[(VRd)hdVLd]23|2<1.8×106.\displaystyle 2\left(1+\frac{1}{\kappa}\right)|\left(\mathcal{G}_{h}^{q}\right)_{32}|^{2}=2\left(1+\frac{1}{\kappa}\right)\frac{\lambda_{3}^{2}u^{4}}{\lambda_{2}^{2}w^{4}}|\left[(V_{R}^{d})^{\dagger}h^{d}V_{L}^{d}\right]_{23}|^{2}<1.8\times 10^{-6}. (46)

The lower bound on the new physics scale ww depends on the choice of other parameters. Due to λ3λ2>1\frac{\lambda_{3}}{\lambda_{2}}>1 and VRd,hdV_{R}^{d},h^{d} not being fixed, the constraints from the mixing mass matrix of the mesons not only translate to the new physics scale, ww, but also translate to other parameters. Therefore, the new physics scale can be chosen far from the Landau pole. The perturbative character of the theory is ensured.

The constraints on the flavor-violating SM-like Higgs boson couplings to the quarks can be translated into upper limits on the branching fraction of the flavor-violating decays of the SM like Higgs boson to light quarks. In our model, the upper limits for the branching ratios of hqiqjh\rightarrow q_{i}q_{j} are predicted to decrease by 11+1k\frac{1}{1+\frac{1}{k}} times that of the predictions in DeltaB ; for details see Table 1. The weakest constraints are in the bbss sector, Br(hbs¯)<3.5×103(h-b\bar{s})<3.5\times 10^{-3}, which is too small to be observed at the LHC because of the large QCD backgrounds, but these signals are expected to be observed at the ILC ILC in the future.

Observable Constraint
D0D^{0} oscillations Br(huc¯)2×1041+1κ(h\rightarrow u\bar{c})\leq\frac{2\times 10^{-4}}{1+\frac{1}{\kappa}}
Bd0B_{d}^{0} oscillations Br(hdb¯)8×1051+1κ(h\rightarrow d\bar{b})\leq\frac{8\times 10^{-5}}{1+\frac{1}{\kappa}}
K0K^{0} oscillations Br(hds¯)2×1061+1κ(h\rightarrow d\bar{s})\leq\frac{2\times 10^{-6}}{1+\frac{1}{\kappa}}
Bs0B_{s}^{0} oscillations Br(hsb¯)7×1031+1κBr(h\rightarrow s\bar{b})\leq\frac{7\times 10^{-3}}{1+\frac{1}{\kappa}}
Table 1: The upper limit on flavor-violating decays of the SM-like Higgs boson to the light quarks at 95%95\% CL from experiments with mesons

.

The flavor-violating Higgs couplings to the quarks given in Eq.(43) leads to the non-standard top-quark decay mode thuit\rightarrow hu_{i}, ui=u,cu_{i}=u,c, the rate for which is given by (here we have neglected terms of 𝒪(mc2mt2)\mathcal{O}(\frac{m_{c}^{2}}{m_{t}^{2}}))

Γ(thui)=|𝒢i3u|2+|𝒢3iu|216π(mt2hh2)2mt3.\displaystyle\Gamma(t\rightarrow hu_{i})=\frac{|\mathcal{G}^{u}_{i3}|^{2}+|\mathcal{G}^{u}_{3i}|^{2}}{16\pi}\frac{\left(m_{t}^{2}-h_{h}^{2}\right)^{2}}{m_{t}^{3}}. (47)

The branching ratio for the decay tuiht\rightarrow u_{i}h is defined as follows

Br(tuih)Γ(tuih)Γ(tbW+),\displaystyle\text{Br}(t\rightarrow u_{i}h)\simeq\frac{\Gamma(t\rightarrow u_{i}h)}{\Gamma(t\rightarrow bW^{+})}, (48)

where Γ(tbW+)g2mt64π(1mW2mt2)(12mW2mt2+mt2mW2)\Gamma(t\rightarrow bW^{+})\simeq\frac{g^{2}m_{t}}{64\pi}\left(1-\frac{m_{W}^{2}}{m_{t}^{2}}\right)\left(1-2\frac{m_{W}^{2}}{m_{t}^{2}}+\frac{m_{t}^{2}}{m_{W}^{2}}\right). The Higgs mediated FCNC in top-quark sector is actively investigated at the LHC by t-FCNC . No signal is observed and the upper limit on the branching fractions Br(thc)<0.16%(t\rightarrow hc)<0.16\% and Br(thu)<0.19%(t\rightarrow hu)<0.19\% at 95%95\% confidence level are obtained. In Fig. 5, we plot the Br(thc)(t\rightarrow hc) in the λ2λ3\frac{\lambda_{2}}{\lambda_{3}}wu\frac{w}{u} plane for fixing [(VRu)huVLu]32=[(VRu)huVLu]23=2mcmtu\left[\left(V_{R}^{u}\right)^{\dagger}h^{u}V_{L}^{u}\right]_{32}=\left[\left(V_{R}^{u}\right)^{\dagger}h^{u}V_{L}^{u}\right]_{23}=2\frac{\sqrt{m_{c}m_{t}}}{u}. The top-quark rare decays into hchc could reach up to 10310^{-3} if the new physics scale is several hundred GeVs, and the factor λ3λ2>5\frac{\lambda_{3}}{\lambda_{2}}>5. In this region of parameter space, the mixing angle ξ\xi is large. The model encounters the difficulties as mentioned in the Sect. IV. Br(tch)(t\rightarrow ch) drops rapidly as the factor wu\frac{w}{u} is increased. For small mixing angle ξ\xi, Br(thc)(t\rightarrow hc) varies from 10510^{-5} to 10810^{-8}. Our results are consistent with t-FCNC1 .

Refer to caption
Figure 5: Top-quark rare decays into hchc.

V Conclusion

We study the non-standard interactions of the SM-like Higgs boson that allows for sizable effects in FCNC processes in the simple 3-3-1 model. We examine some effects in flavor physics and constraints on the model both from the quark and lepton sectors via renormalizable and non-renormalizable Yukawa interactions. Specifically, due to the couplings of the leptons to both Higgs triplets, it creates the lepton flavor-violating couplings at tree level. The existence of these interactions is completely independent of the source of non-zero neutrino masses and mixing. This means that, if the source generating mass for neutrinos is turned off, the lepton flavor-violation processes such as hliljh\rightarrow l_{i}l_{j} or liljγl_{i}\rightarrow l_{j}\gamma… are perfectly possible. The branching for hμτh\rightarrow\mu\tau decay depends on the non-renormalizable Yukawa coupling heh^{\prime e}, the mixing angle ξ\xi, and the new physical scale. For large mixing angle ξ\xi, Br(hμτ)(h\rightarrow\mu\tau) can reach the experimental upper bound of the ATLAS and CMS, while for small mixing angle, Br(hμτ)(h\rightarrow\mu\tau) can be 10510^{-5}. The τμγ\tau\rightarrow\mu\gamma radiative decay is considered by both lepton flavor-conserving and -violating couplings. The contributions coming from two-loop diagrams with lepton flavor-violating vertex and all one-loop diagrams (including lepton flavor-violating/conserving vertexes) are comparable. The lepton flavor-violating contribution to (g2)μ(g-2)_{\mu} is suppressed if the parameters are selected to satisfy the limits from hμτh\rightarrow\mu\tau and τμγ\tau\rightarrow\mu\gamma, while the flavor-conserving coupling of the muon to the new gauge boson Yμ±±Y_{\mu}^{\pm\pm} almost allows one to explain the muon’s anomalous magnetic moment, (Δaμ)331<13.8×1010(\Delta a_{\mu})_{331}<13.8\times 10^{-10}, due to the constraint of LHC over the ZZ^{\prime} mass.

We investigate the flavor-violating interactions of the Higgs boson with a pair of quarks. These interactions not only generate the FCNC, which are testable in Bs,d,K0B_{s,d},K^{0} meson oscillation experimental but also introduce the additional decay modes for the Higgs boson. The binding conditions from the meson oscillation experiment were transferred to the upper limit on the branching ratio of these decay. They are 11+1κ\frac{1}{1+\frac{1}{\kappa}} smaller than the predictions given in DeltaB .Directly testing these Higgs decays seems to be outside the LHC reach but they are promising as regards searching in the future ILC ILC . A search for FCNC in events with the top quark is presented. The upper bound on the branching fraction of top-quark decay, thct\rightarrow hc strongly depends on the new physics scale. It can reach 10510^{-5} or be as low as 10810^{-8}.

Acknowledgments

This research is funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant number 103.01-2019.312.

References

  • (1) G. Aad et al. (ATLAS Collaboration), Phys. Lett. B 716, 1 (2012); S. Chatrchyan et al. (CMS Collaboration), Phys. Lett. B 716, 30 (2012).
  • (2) J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).
  • (3) A. M. Sirunyan, et al., JHEP 06, 102, (2018); ATLAS Collaboration, Phys. Rev. D 98, 032002, (2018);
  • (4) R. Harnik, J. Kopp, J. Zupan, JHEP 03, 026, (2013); M.Ilyushin, P.Mandrik, S.Slabospitsky, Arxiv: 1905.03906 [hep-ph];
  • (5) F. Pisano and V. Pleitez, Phys. Rev. D 46, 410 (1992); R. Foot, O. F. Hernandez, F. Pisano and V. Pleitez, Phys. Rev. D 47, 4158 (1993).
  • (6) P. H. Frampton, Phys. Rev. Lett. 69, 2889 (1992).
  • (7) M. Singer, J. W. F. Valle and J. Schechter, Phys. Rev. D 22, 738 (1980); J. C. Montero, F. Pisano and V. Pleitez, Phys. Rev. D 47, 2918 (1993); R. Foot, H. N. Long and T.A. Tran, Phys. Rev. D 50, 34 (1994).
  • (8) W. A. Ponce, Y. Giraldo and L. A. Sanchez, Phys. Rev. D 67, 075001 (2003); P. V. Dong, H. N. Long, D. T. Nhung and D. V. Soa, Phys. Rev. D 73, 035004 (2006); P. V. Dong and H. N. Long, Adv. High Energy Phys. 2008, 739492 (2008); P. V. Dong, T.T. Huong, D. T. Huong, and H. N. Long, Phys. Rev. D 74, 053003 (2006); P. V. Dong, H. N. Long, and D. V. Soa, Phys. Rev. D 73, 075005 (2006); P. V. Dong, H. N. Long, and D. V. Soa, Phys. Rev. D 75, 073006 (2007); P.V. Dong, D.T. Huong, M.C. Rodriguez, and H. N. Long, Nucl. Phys. B 772, 150 (2007); P. V. Dong, H. T. Hung, and H. N. Long, Phys. Rev. D 86, 033002 (2012).
  • (9) J. G. Ferreira Jr., P. R. D. Pinheiro, C. A. de Pires, and P. S. da Rodrigues, Phys. Rev. D 84, 095019 (2011).
  • (10) S. M. Boucenna, J. W. F. Valle, and A. Vicente, Phys.Rev. D 92, 053001 (2015); G. Arcadi, C.P. Ferreira, F. Goertz, M.M. Guzzo, F. S. Queiroz, A.C.O. Santos, Lepton flavor violation induced by dark matter, Phys. Rev. D 97, 075022 (2018); M. Lindner, M. Platscher, and F. S. Queiroz, Phys.Rep. 731, 1 (2018); L.T. Hue, L.D. Ninh, T.T. Thuc, and N.T.T. Dat, Eur.Phys.J. C 78, 128 (2018); T. Phong Nguyen, T.Le. Thuy, T. T. Hong, L. T. Hue, Phys. Rev. D 97, 073003 (2018); L. T. Hue, D. T. Huong, H. N. Long, Nucl.Phys.B 873, 207-247, (2013); P. T. Giang, L. T. Hue, D. T. Huong, H. N. Long, Nucl. Phys. B, 864,85-112, (2012);
  • (11) A.J. Buras, F.De Fazio, J.Girrbach-Noe, JHEP 08, 039, (2014); R.H. Benavides, Y. Giraldo, W.A. Ponce, Phys.Rev.D 80, 113009,(2009); A. C. B. Machado, J. C. Montero, V. Pleitez, Phys. Rev. D 88, 113002, (2013);C. Promberger, S. Schatt, F. Schwab, Phys. Rev. D 75, 115007,(2007); P. Van Dong, L. Tho Hue, D. Thi Huong, H.N. Long, Physics. Commun. 24, 13-17, (2014).
  • (12) ] D. Fregolente and M. D. Tonasse, Phys. Lett. B 555, 7 (2003); H. N. Long and N. Q. Lan, Europhys. Lett. 64, 571 (2003); S. Filippi, W. A. Ponce, and L. A. Sanches, Europhys. Lett. 73, 142 (2006); C.A.S. de Pires, P. S. da Rodrigues, JCAP 712, 12 (2007); J. K. Mizukoshi, C.A.S. de Pires, F. S. Queiroz, and P. S. da Rodrigues, Phys. Rev. D 83, 065024 (2011); J. D. Ruiz-Alvarez, C.A.S. de Pires, F. S. Queiroz, D. Restrepo, and P. S. da Rodrigues, Phys. Rev. D 86, 075011 (2012); P. V. Dong, T. Phong Nguyen, and D. V. Soa, Phys. Rev. D 88, 095014 (2013); S. Profumo and F. S. Queiroz, Eur. Phys. J. C 74, 2960 (2014); C. Kelso, C.A.S. de Pires, S. Profumo, F. S. Queiroz, and P. S. da Rodrigues, Eur. Phys. J. C 74, 2797 (2014); P. S. da Rodrigues, Phys. Int.7, 15 (2016);
  • (13) P. V. Dong, T. D. Tham, and H. T. Hung, Phys. Rev. D 87, 115003 (2013); P. V. Dong, D. T. Huong, F. S. Queiroz, and N. T. Thuy, Phys. Rev. D 90, 075021 (2014); D. T. Huong, P. V. Dong, C. S. Kim, and N. T. Thuy, Phys. Rev. D 91, 055023 (2015); D. T. Huong and P. V. Dong, Eur. Phys. J. C 77, 204 (2017); A. Alves, G. Arcadi, P. V. Dong, L. Duarte, F. S. Queiroz, and J. W. F. Valle, Phys. Lett. B 772, 825 (2017); P. V. Dong, D. T. Huong, D. A. Camargo, F. S. Queiroz, and J. W. F. Valle, Phys. Rev. D 99, 055040 (2019);
  • (14) J. G. Ferreira Jr, P. R. D. Pinheiro, C. A. de S. Pires, and P. S. Rodrigues da Silva, Phys. Rev. D 84, 095019 (2011).
  • (15) P. V. Dong, N. T. K. Ngan, D. V. Soa,Phys. Rev. D 90, 075019 (2014); P. Van Dong, N. T. K. Ngan, T. D. Tham, L. D. Thien, N. T. Thuy, Phys. Rev. D 99, 095031 (2019).
  • (16) P. V.Dong, D. T. Si, Phys. Rev. D 90, 11, 117703 (2014).
  • (17) M. B. Tully and G. C. Joshi, Phys. Rev. D 64, 011301 (2001); A.G. Dias, C.A.S. de Pires,and P. S. da Rodrigues Silva, Phys. Lett. B 628, 85 (2005); D. Chang and H. N. Long, Phys. Rev. D 73, 053006 (2006); P. V. Dong, H. N. Long, and D. V. Soa, Phys. Rev. D 75, 073006 (2007); P. V. Dong and H. N. Long, Phys. Rev. D 77, 057302 (2008); P. V. Dong, L. T. Hue, H. N. Long, and D. V. Soa, Phys. Rev. D 81, 053004 (2010); P. V. Dong, H. N. Long, D. V. Soa, and V. V. Vien, Eur. Phys. J. C 71, 1544 (2011); P. V. Dong, H. N. Long, C. H. Nam, and V. V. Vien, Phys. Rev. D 85, 053001 (2012); S. M. Boucenna, S. Morisi, and J. W. F. Valle, Phys. Rev. D 90, 013005 (2014); S. M. Boucenna, R. M. Fonseca, F. Gonzalez-Canales, and J. W. F. Valle, Phys. Rev. D 91, 031702 (2015); S. M. Boucenna, J. W. F. Valle, and A. Vicente, Phys. Rev. D 92, 053001 (2015); H. Okada, N. Okada, and Y. Orikasa, Phys. Rev. D 93, 073006 (2016); C.A.S. de Pires, Phys. Int 6, 33 (2015).
  • (18) P. B. Pal, Phys. Rev. D 52, 1659 (1995); A. G. Dias, C.A.S. de Pires, and P. S. R. da Silva, Phys. Rev. D 68 , 115009 (2003); A. G. Dias and V. Pleitez, Phys. Rev. D 69, 077702 (2004); P. V. Dong, H. T. Hung, and H. N. Long, Phys. Rev. D 86, 033002 (2012).
  • (19) F. Pisano, Mod. Phys. Lett A 11, 2639 (1996); A. Doff and F. Pisano, Mod. Phys. Lett. A 14, 1133 (1999); C.A.S. de Pires and O. P. Ravinez, Phys. Rev. D 58, 035008 (1998); C.A. S. de Pires, Phys. Rev. D 60 , 075013 (1999); P. V. Dong and H. N. Long, Int. J. Mod. Phys. A 21, 6677 (2006).
  • (20) L.T. Hue, L.D. Ninh, T.T. Thuc, N.T.T. Dat, Eur. Phys. J. C 78, 128 (2018).
  • (21) L. Lavoura,Eur.Phys.J.C 29,191-195, (2003).
  • (22) S. Davidson, G. Grenier, Phys.Rev.D 81,095016, (2010).
  • (23) D.T. Binh, D.T. Huong, L. T. Hue, H.N. Long, Commun. Phys, 25,1, 29-43 (2015).
  • (24) C. Kelso, P. R. D. Pinheiro, F.S. Queiroz, W.Shepherd, Eur. Phys. J. C 74, 2808 (2014).
  • (25) K. Hagiwara, R. Liao, A. D. Martin, D. Nomura and T. Teubner, J. Phys. G 38, 085003 (2011); T. Nomura and H. Okada, Phys. Rev. D 97, no. 9, 095023 (2018); R. H. Parker, C. Yu, W. Zhong, B. Estey and H. Muller, Science 360, 191 (2018).
  • (26) D. T. Huong, P. V. Dong, N. T. Duy, N. T. Nhuan, L. D. Thien, Phys. Rev. D 98, 055033 (2018); D. N. Dinh, D. T. Huong, N. T. Duy, N. T. Nhuan, L. D. Thien, Phung Van Dong, Phys. Rev. D 99, 055005 (2019); D. T. Huong, D. N. Dinh, L. D. Thien, P. Van Dong, JHEP 08, 051 (2019).
  • (27) M. Bona et al. (UTfit Collaboration), JHEP 0803, 049 , (2008); R. Harnik, J. Kopp, J. Zupan, JHEP 03, 026, (2013).
  • (28) M. Aaboud, et al, Phys. Rev. D 98, 032002 (2018).
  • (29) J.A. Aguilar-Saavedra, Acta Phys. Polon. B 35, 2695 (2004); J.A. Aguilar-Saavedra, G.C. Branco, Phys. Lett. B 495, 347 (2000);B. Grzadkowski, J.F. Gunion, P. Krawczyk, Phys. Lett. B 268, 106-111 (1991) J.L. Diaz-Cruz, R. Martinez,M.A. Perez and A. Rosado, Phys. Rev. D 41, 891 (1900); G. Eilam, J.L. Hewett, A. Soni, Phys. Rev. D 44, 1473 (1991), see also: Erratum, Phys. Rev. D 59, 039901 (1999); B. Mele, S. Petrarca, A. Soddu, Phys. Lett. B 435, 401 (1998); A. Arhrib, Phys. Lett. B 612, 263 (2005).
  • (30) D. Barducci, A.J. Helmboldt, JHEP 12, 105 (2017).
  • (31) T. P. Cheng and M. Sher, Phys. Rev. D 35, 3484 (1987).