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The flavor changing neutral current (FCNC) transitions provide a critical test of the Cabibbo-Kobayashi-Maskawa (CKM) mechanism in the Standard Model (SM), and allow to search for possible new physics. In SM, the FCNC transition
s→dνˉν proceeds through the Z-penguin and electroweak box diagrams, and thus the decay probabilities are strongly suppressed. In this case, a precise study allows to perform very stringent tests of SM and ensures large sensitivity to potential new degrees of freedom.A large number of studies have been performed of the
K+→π+νˉν andKL→π0νˉν processes, and reviews of these two decay modes can be found in [1–6]. On the theoretical side, using the most recent input parameters, the SM predictions for the two branching ratios are [7]B(K+→π+νˉν)SM=(8.4±1.0)×10−11,
(1) B(KL→π0νˉν)SM=(3.4±0.6)×10−11.
(2) The dominant uncertainty comes from the CKM matrix elements and the charm contribution. On the experimental side, the NA62 experiment at the CERN SPS has reported the first search for
K+→π+νˉν using the decay-in-flight technique, and the corresponding observed upper limit is [8] :B(K+→π+νˉν)exp<14×10−10,at 95% CL.
(3) Similarly, the E391a collaboration reported the 90% C.L. upper bound [9]
B(KL→π0νˉν)exp⩽2.6×10−8.
(4) The KOTO experiment, an upgrade of the E391a experiment, aims at a first observation of the
KL→π0νˉν decay at J-PARC around 2020 [3, 10]. Given the goal of a 10% precision by NA62, the authors of Ref. [11] intend to carry out lattice QCD calculations to determine the long-distance contributions to theK+→π+νˉν amplitude.Analogous to
K+→π+νˉν andKL→π0νˉν , the rare hyperon decaysBi→Bfνˉν also proceed vias→dνˉν at the quark level, and thus offer important tools to test SM and to search for possible new physics. Compared to the widely consideredK+→π+νˉν andKL→π0νˉν , there are few studies devoted to rare hyperon decaysBi→Bfνˉν . This work aims to perform a preliminary theoretical research of the rare hyperon decays both in and beyond SM.A study of the hyperon decays at the BESIII experiment is proposed using the hyperon parents of the
J/ψ decay. The electron-positron collider BEPCII provides a clean experimental environment. About106 -108 hyperons, Λ, Σ, Ξ and Ω, are produced in theJ/ψ andψ(2S) decays with the proposed data samples at the BESIII experiment. Based on these samples, the sensitivity of the measurement of the branching ratios of hyperon decays is in the range of10−5 -10−8 . The author of Ref. [12] proposed that rare decays and decays with invisible final states may be probed.The paper is organized as follows. In Sec. 2, our computing framework is presented. Sec. 3 is devoted to performing the numerical calculations. The branching ratios of several rare hyperon decays are calculated in SM. The new physics contribution, the Minimal Supersymmetric Standard Model (MSSM) and the minimal 331 model, are considered. We also discuss possible uncertainties from the form factors. The last section contains a short summary.
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The next-to-leading order (NLO) effective Hamiltonian for
s→dνˉν reads [13]:Heff=GF√2α2πsin2θW∑l=e,μ,τ[V∗csVcdXlNL+V∗tsVtdX(xt)](ˉsd)V−A(ˉνlνl)V−A+h.c.,
(5) where
X(xt) andXlNL are relevant for the top and the charm contribution, respectively. Their explicit expressions can be found in Ref. [13]. Here,xt=m2t/m2W . To leading order inαs , the functionX(xt) relevant for the top contribution reads [14, 15]X(x)=X0(x)+αs4πX1(x),X0(x)=x8[−2+x1−x+3x−6(1−x)2lnx],X1(x)=−23x+5x2−4x33(1−x)2+x−11x2+x3+x4(1−x)3lnx+8x+4x2+x3−x42(1−x)3ln2x−4x−x3(1−x)2L2(1−x)+8x∂X0(x)∂xlnxμ,
(6) where
xμ=μ2/M2W withμ=O(mt) andL2(1−x)=∫x1dtlnt1−t.
(7) The function
XlNL corresponds toX(xt) in the charm sector. It results from the renormalization group (RG) calculation in next-to-leading-order logarithmic approximation (NLLA) and is given as follows:XlNL=CNL−4B(1/2)NL,
(8) where
CNL andB(1/2)NL correspond to theZ0 -penguin and the box-type contribution, respectively, given as [16]CNL=x(mc)32K2425c[(487K++2411K−−69677K33)(4παs(μ)+152121875(1−K−1c))+(1−lnμ2m2c)(16K+−8K−)−117624413125K+−23026875K−+352918448125K33+K(562484375K+−814486875K−+4563698144375K33)],B(1/2)NL=x(mc)4K2425c[3(1−K2)(4παs(μ)+152121875(1−K−1c))−lnμ2m2c−rlnr1−r−30512+15212625K2+155817500KK2],
(9) where
r=m2l/m2c(μ) ,μ=O(mc) andK=αs(MW)αs(μ),Kc=αs(μ)αs(mc),K+=K625,K−=K−1225,K33=K2=K−125.
(10) In the following, we consider the transitions between the baryon octet (Ξ, Σ, Σ and N) and the transitions from the baryon decuplet to the octet
Ω−→Ξ− .The transition matrix elements of the vector and axial-vector currents between the baryon octets can be parametrized in terms of six form factors
f1,2,3(q2) andg1,2,3(q2) :⟨B′8(P′,S′z)|ˉdγμ(1−γ5)s|B8(P,Sz)⟩=ˉu(P′,S′z)[γμf1(q2)+iσμνqνMf2(q2)+qμMf3(q2)]u(P,Sz)−ˉu(P′,S′z)[γμg1(q2)+iσμνqνMg2(q2)+qμMg3(q2)]γ5u(P,Sz),
(11) where
q=P−P′ , and M denotes the mass of the parent baryon octetB8 . The form factors for theB8→B′8 transition,fi(q2) andgi(q2) , can be expressed by the following formulas [17]:fm=aFm(q2)+bDm(q2),gm=aFm+3(q2)+bDm+3(q2),(m=1,2,3),
(12) where
Fi(q2) andDi(q2) , withi=1,2,⋯,6 , are different functions ofq2 for each of the six form factors. Some remarks are necessary [17]:● The constants a and b in Eq. (12) are the SU(3) Clebsch-Gordan coefficients that appear when an octet operator is sandwiched between octet states.
● For
q2=0 , the form factorf1(0) is equal to the electric charge of the baryon, thereforeF1(0)=1 andD1(0)=0 .● The weak
f2(0) form factor can be computed using the anomalous magnetic moments of proton and neutron (κp andκn ) in the exact SU(3) symmetry. Here,F2(0)=κp+12κn andD2(0)=−32κn .●
g1(0) is a linear combination of two parameters, F and D.● Since
gn→p2=F5(q2)+D5(q2)=0 andgΞ−→Ξ02= D5(q2)−F5(q2)=0 , we getF5(q2)=D5(q2)=0 . Therefore, all pseudo-tensor form factorsg2 vanish in all decays up to symmetry-breaking effects.● In the
s→dˉνν decay, thef3 andg3 terms are proportional to the neutrino mass and thus can be neglected for the decays considered in this work.Since the invariant mass squared of lepton pairs in the hyperon decays is relatively small, it is expected that the
q2 distribution in the form factors has small impact on the decay widths. We list the expressions forf1 ,f2 andg1 atq2=0 in Table 1.B→B′ Λ→n Σ+→p Ξ0→Λ Ξ0→Σ0 Ξ−→Σ− f1(0) −√32 −1 √32 − 1√2 1 f2(0) −√32κp −(κp+2κn) √32(κp+κn) −1√2(κp−κn) κp−κn g1(0) −√32(F+D/3) −(F−D) √32(F−D/3) −1√2(F+D) F+D Table 1. The form factors for the
B→B′ transition,f1(0) ,f2(0) andg1(0) [17], where the experimental anomalous magnetic moments areκp=1.793±0.087 andκn=−1.913±0.069 [18], with the two coupling constantsF=0.463±0.008 andD=0.804±0.008 [18]. Here,g1/f1 is positive for the neutron decay, and all other signs are fixed using this sign convention.Hence, Eq. (11) can be rewritten as:
⟨B′8(P′,S′z)|ˉdγμ(1−γ5)s|B8(P,Sz)⟩=ˉu(P′,S′z)[γμf1(q2)+iσμνqνMf2(q2)−γμg1(q2)γ5]u(P,Sz).
(13) The helicity amplitudes of the hadronic contribution are defined as
HVλ′,λV≡⟨B′8(P′,λ′)|ˉdγμs|B8(P,λ)⟩ϵ∗Vμ(λV),
(14) HAλ′,λV≡⟨B′8(P′,λ′)|ˉdγμγ5s|B8(P,λ)⟩ϵ∗Vμ(λV).
(15) Here,
λ(′) denotes the helicity of the parent (daughter) baryon in the initial (final) state, andλV is the helicity of the virtual intermediate vector particle. It can be shown that the helicity amplitudesHV,Aλ′,λV have the following simple forms [19]:HV12,0=−i√Q−√q2[(M+M′)f1−q2Mf2],HA12,0=−i√Q+√q2(M−M′)g1,HV12,1=i√2Q−[−f1+M+M′Mf2],HA12,1=−i√2Q+g1.
(16) In the above,
Q±=(M±M′)2−q2 , andM (M′ ) is the parent (daughter) baryon mass in the initial (final) state. The amplitudes for the negative helicity are obtained from the relations,HV−λ′,−λV=HVλ′,λV,HA−λ′,−λV=−HAλ′,λV.
(17) The complete helicity amplitudes are obtained by
Hλ′,λV=HVλ′,λV−HAλ′,λV.
(18) Due to the lack of experimental data for the
M1 andE2 transitions from the baryon decuplet to the octet, the vector transition matrix element forΩ−→Ξ− can not be determined. In this work we follow Ref. [18] , and consider only the axial-vector current matrix element [18, 20, 21]:⟨Ξ−(P′,S′z)|ˉdγμγ5s|Ω−(P,Sz)⟩=ˉuΞ−(P′,S′z){CA5(q2)gμν+CA6(q2)qμqν+[CA3(q2)γα+CA4(q2)p′]×(qαgμν−qνgαμ)}uνΩ−(P,Sz).
(19) Here,
uνΩ−(P,Sz) represents the Rarita-Schwinger spinor that describes the baryon decupletΩ− with spin32 . In Ref. [22] it is shown thatCA3(q2) andCA4(q2) are proportional to the mass difference of the initial and final baryons, and thus are suppressed. In the chiral limit,CA5(q2) andCA6(q2) are related byCA6(q2)=M2NCA5(q2)/q2 [20]. In our calculations, we useCA5(0)=1.653±0.006 forΩ−→Ξ− , which is the same asΩ−→Ξ0 in the SU(3) limit [18]. The helicity amplitude can then be expressed as:HAλ′,λV=⟨Ξ−(P′,λ′)|ˉdγμγ5s|Ω−(P,λ)⟩ϵ⋆μV(λV)
(20) =ˉuΞ−(P′,λ′)[CA5(q2)gμν+CA6(q2)qμqν]uνΩ−(P,λ)ϵ⋆μV(λV).
(21) Here,
λ(′) andλV have the same definition as in Eqs. (14)-(15). It can be shown that the helicity amplitudesHAλ′,λV have the following simple forms [19]:HA12,0=HA−12,0=i√2Q+3EV√q2CA5(q2),HA12,1=HA−12,−1=i√Q+3CA5(q2),HA12,−1=HA−12,1=i√Q+CA5(q2).
(22) The differential decay width for
B→B′ˉνν is given as:dΓdq2=dΓLdq2+dΓTdq2.
(23) Here,
dΓL/dq2 anddΓT/dq2 are the longitudinal and transverse parts of the decay width, and their explicit expressions are given bydΓLdq2=Nq2p′12(2π)3M2(|H12,0|2+|H−12,0|2),
(24) dΓTdq2=Nq2p′12(2π)3M2(|H12,1|2+|H−12,−1|2+|H12,−1|2+|H−12,1|2).
(25) In Eqs. (24) and (25),
p′=√Q+Q−/2M is the magnitude of the momentum ofB′ in the rest frame ofB , andN=2N1(0)+N1(mτ) withN1(ml)=|GF√2α2πsin2ΘW(V∗cdVcsXlNL(ml)+V∗tdVtsX(xt))|2.
(26) Note that we have neglected the electron and muon masses.
One can then obtain the decay width
Γ=∫(M−M′)20dq2dΓdq2.
(27) -
With the input parameters given in Table 2 and the formulae from the last section, the LO and NLO results for
μc = 1 GeV,μt = 100 GeV , andμc=3GeV, μt=300GeV , are listed Table 3.The masses and lifetimes of baryons in the initial and final states [23] mp=938.2720813 MeVmΣ+=1189.37 MeVmΞ0=1314.86 MeVmn =939.5654133 MeVmΣ−=1197.45 MeVmΞ−=1321.71 MeVmΛ=1115.683 MeVmΣ0=1192.642 MeVmΩ−=1672.45 MeVτΞ0=2.90×10−10s τΞ−=1.639×10−10s τΩ−=0.821×10−10s τΛ=2.632×10−10s τΣ+=0.8018×10−10s Physical constants and CKM parameters [23, 24] GF=1.16637387×10−5GeV−2 sin2θW=0.23122 αs (mZ )=0.1182 α≡α (mZ )=1/128 mτ =1776.86 MeVmc=1.275 GeVmt=173.0 GeVmW =80.379 GeVmZ =91.1876 GeVA=0.836 λ=0.22453 ˉρ=0.122 ˉη=0.355 Table 2. The input parameters used in this work.
Branching ratio B(Λ→nνˉν) B(Σ+→pνˉν) B(Ξ0→Λνˉν) B(Ξ0→Σ0νˉν) B(Ξ−→Σ−νˉν) B(Ω−→Ξ−νˉν) μc=1 GeVLO 2.85×10−12 6.88×10−13 1.06×10−12 1.77×10−13 2.17×10−13 1.78×10−11 NLO 1.98×10−12 5.01×10−13 7.35×10−13 1.24×10−13 1.52×10−13 1.93×10−11 μt=100 GeVNLO+SUSY (Set.I) 8.14×10−12 2.06×10−12 3.02×10−12 5.08×10−13 6.23×10−13 7.94×10−11 NLO+SUSY (Set.II) 3.78×10−12 9.55×10−13 1.40×10−12 2.36×10−13 2.89×10−13 3.69×10−11 NLO+ M331 1.24×10−11 3.13×10−12 4.59×10−12 7.71×10−13 9.45×10−13 1.20×10−10 μc=3 GeVLO 1.10×10−12 2.65×10−13 4.10×10−13 6.83×10−14 8.37×10−14 1.07×10−11 NLO 1.20×10−12 3.04×10−13 4.46×10−13 7.50×10−14 9.19×10−14 1.17×10−11 μt=300 GeVNLO+SUSY (Set.I) 5.85×10−12 1.48×10−12 2.17×10−12 3.65×10−13 4.47×10−13 5.71×10−11 NLO+SUSY (Set.II) 2.35×10−12 5.94×10−13 8.72×10−13 1.47×10−13 1.80×10−13 2.29×10−11 NLO+ M331 1.02×10−11 2.58×10−12 3.80×10−12 6.37×10−13 7.81×10−13 9.95×10−11 BESIII sensitivity [12] 3×10−7 4×10−7 8×10−7 9×10−7 − 2.6×10−5 Table 3. The LO, NLO, NLO+SUSY and NLO+
M331 results for the branching ratio of rare hyperon decays forμc=1 GeV,μt=100 GeV andμc=3 GeV,μt=300 GeV. From the results in Table 3 one can see that:
● The branching ratios of the
s→dνˉν rare hyperon decays range from10−14 to10−11 .● For
μc=1GeV,μt=100GeV , the NLO results are smaller than the LO ones by about 30%, while forμc=3GeV,μt=300GeV , the NLO results are larger than the LO ones by about 10%.● The LO results vary by about 50% from
μc=1 GeV, μt=100 GeV toμc=3GeV,μt=300GeV , while the NLO ones vary by about 30%. As expected, the NLO results depend less on the mass scales.● The branching ratio of
Ω−→Ξ−νˉν is the largest among the 6 channels. It is of the same order as forK+→π+νˉν andKL→π0νˉν .At present, there is a small number of experimental studies, and thus most experimental constraints are less severe. The prospects for rare and forbidden hyperon decays at BESIII were analyzed in a recent publication Ref. [12]. We quote the experimental sensitivity for all decay modes in Table 3 . Unfortunately, one can see that the current BESIII experiment will not be able to probe these hyperon decays. We hope this may be improved at future experimental facilities like the Super Tau-Charm Factory.
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Note that due to the Ademollo-Gatto theorem [25], the form factor
f1(0) does not receive any SU(3) symmetry breaking correction. However,f2(0) can be computed using the anomalous magnetic moments of proton and neutron (κp andκn ) in the exact SU(3) symmetry. The experimental data forκp andκn already include the SU(3) symmetry breaking effects [18]:κp[O(m0s)]=1.363±0.069,κp[O(m0s)]=−1.416±0.049,
(28) κp[O(m0s)+O(m1s)]=1.793±0.087,κp[O(m0s)+O(m1s)]=−1.913±0.069.
(29) The uncertainties from
κp andκn in the effect of SU(3) symmetry breaking is approximately 25%. We calculated the effect ofκp andκn on the branching ratio ofΣ+→pνˉν in the case of NLO with the energy scaleμc=1GeV andμt=100GeV such that:B(Σ+→pνˉν)[O(m0s)]=(4.86±0.04)×10−13,B(Σ+→pνˉν)[O(m0s)+O(m1s)]=(5.01±0.08)×10−13.
(30) Next, we consider the uncertainty of the branching ratio of
Σ+→pνˉν andΛ→nνˉν in the case of NLO with the energy scaleμc=1GeV andμt=100GeV . This uncertainty comes from the parametersF=0.463±0.008 andD=0.804±0.008 [18] in the form factorg1(0) :B(Σ+→pνˉν)=(5.01±0.12)×10−13,B(Λ→nνˉν)=(2.03±0.05)×10−12.
(31) For the decay
Ω−→Ξ−νˉν ,CA5(0)=1.653±0.006 in the SU(3) symmetry, whileCA5(0)=1.612±0.007 in the SU(3) symmetry breaking [18]. In the case of NLO with the energy scaleμc=1 GeV andμt=100 GeV the branching ratioB(Ω−→Ξ−νˉν) is then calculated as:B(Ω−→Ξ−νˉν)(sy)=(1.84±0.01)×10−11,B(Ω−→Ξ−νˉν)(br)=(1.93±0.01)×10−11.
(32) As an illustration of the effects of
q2 distribution in the form factors, we attempt to use the following parametrization for all form factors:F(q2)=F(0)1−q2m2,
(33) with
m representing the initial hyperon mass. For example, for the NLO case ofμc=1GeV andμt= 100 GeV, we obtain:B(Λ→nνˉν)(F(0))=1.98×10−12,B(Λ→nνˉν)(F(q2))=2.03×10−12,B(Σ+→pνˉν)(F(0))=5.05×10−13,B(Σ+→pνˉν)(F(q2))=5.16×10−13.
(34) We find that the differences between the two cases are small, about a few percent.
When all the above errors in the form factors are included, we find that the final branching ratios for most decay modes have an uncertainty of about 5% to 10% .
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The effective Hamiltonian for
s→dνˉν in the generalized supersymmetry (SUSY) extension of SM is given in Eq. (5), withX(xt) replaced by [26]Xnew=X(xt)+XH(xtH)+Cχ+CN.
(35) Here,
xtH=m2t/m2H± , andXH(xtH) corresponds to the charged Higgs contribution.Cχ andCN denote the chargino and neutralino contributionsCχ=X0χ+XLLχRUsLdL+XLRχRUsLtR+XLR∗χRUtRdL,CN=XNRDsLdL,
where
Xiχ andXN depend on the SUSY masses, and respectively on the chargino and neutralino mixing angles. The explicit expressions forXH(x) ,Cχ andCN can be found in Ref. [26]. The R parameters are defined in terms of mass insertions, and their upper limits are listed in Table 4 [26]. It should be mentioned that the phaseϕ ofRUsLtR andRUtRdL is a free parameter which ranges from 0 to2π . We setϕ=0 as a central result.quantity upper limit RDsLdL (−112−55i)m˜dL500GeV RUsLdL (−112−54i)m˜uL500GeV RUsLtR Min{231(m˜uL500GeV)3,43}×eiϕ,0<ϕ<2π RUtRdL 37(m˜uL500GeV)2×eiϕ,0<ϕ<2π Table 4. Upper limits for the R parameters. Note that the phase of
RUsLtR andRUtRdL is unconstrained.The parameters in Table 5 are adopted for detailed calculations [27]. The assumption
M1≈0.5M2 was made [28]. With the above parameters, the branching ratios of hyperon decays are listed in Table 3, and are significantly enhanced compared with the SM results. Taking as examples the decaysΛ→nνˉν andΩ−→Ξ−νˉν with the energy scaleμc=1 GeV andμt=100 GeV , we obtain:parameters [27] the meaning of parameters [27] the range of parameters [27] Set.I [27] Set.II [27] β The angle of unitarity triangle −180∘⩽β⩽180∘ tanβ=2 tanβ=20 MA CP-odd Higgs boson mass 150⩽MA⩽400 333 260 M2 SU(2) gaugino mass; we useM1 GUT-related toM2 50⩽M2⩽800 181 750 μ Supersymmetric Higgs mixing parameter −400⩽μ⩽400 −375 −344 Msl Common flavour diagonal slepton mass parameter 95⩽Msl⩽1000 105 884 Msq Common mass parameter for the first two generations of squarks 240⩽Msq⩽1000 308 608 M˜tL Squark mass parameter for the right stop 50⩽M˜tR⩽1000 279 338 Table 5. Parameters and their ranges used in Ref. [27]. All mass parameters are in GeV.
NLO: B(Λ→nνˉν)=1.98×10−12,B(Ω−→Ξ−νˉν)=1.93×10−11,
(36) Set.I: B(Λ→nνˉν)=8.14×10−12,B(Ω−→Ξ−νˉν)=7.94×10−11,
(37) Set.II: B(Λ→nνˉν)=3.78×10−12,B(Ω−→Ξ−νˉν)=3.69×10−11.
(38) Comparing the results of NLO+SUSY (Set. I) and (Set. II) with the ones of NLO, we see that all branching ratios are roughly enhanced by a factor of 4 and 2, respectively. However, none of these results can be probed at the ongoing experimental facilities, like the BESIII experiment [12].
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The so-called minimal
331 model is an extension of SM at the TeV scale, where the weak gauge group of SMSU(2)L is extended toSU(3)L . In this model, a new neutralZ′ gauge boson can give very important additional contributions, for it can transmit FCNC at the tree level. In Table 3, we denote this model as M331. More details of this model can be found in Ref. [29]. The minimal 331 model leads to a new term in the effective Hamiltonian [30]:HZ′eff=∑l=e,μ,τGF√2˜V∗32˜V313(MZMZ′)2cos2θW(ˉsd)V−A(ˉνlνl)V−A+h.c.,
(39) with
MZ′=1TeV ,Re[(˜V∗32˜V31)2]=9.2×10−6 andIm[(˜V∗32˜V31)2]=4.8×10−8 [30]. The other parameters are the same as the SM inputs [23, 24]. The functionX(xt) in Eq. (5) can be redefined asX(xt)=XSM(xt)+ ΔX withΔX=sin2θWcos2θWα2π3˜V∗32˜V31V∗tsVtd(MZMZ′)2.
(40) With the modified function
X(xt) and considering the NLO contribution, the branching ratios of rare hyperon decays in the minimal 331 model can be calculated, as shown in Table 3. The NLO+M331 predictions are much larger than the NLO results in SM, and are two and four times larger than the results of NLO+SUSY (Set. I) and NLO+SUSY (Set. II), respectively. -
FCNC processes offer important tools to test SM and to search for possible new physics. The two decays
K+→π+νˉν andKL→π0νˉν have been widely studied, while the corresponding baryon sector has not been explored. In this work, we studied thes→dνˉν rare hyperon decays. We adopted the leading order approximations for the form factors for smallq2 , and derived expressions for the decay width. We applied the decay width formula to both SM and new physics contributions. Different energy scales were considered. The branching ratios in SM range from10−14 to10−11 , and the largest is of the same order as for the decaysK+→π+νˉν andKL→π0νˉν . When all the errors in the form factors are included, we found that the final branching ratios for most decay modes have an uncertainty of about 5% to 10%. After taking into account the contribution from MSSM, the branching ratios are enhanced by a factor of2∼4 . The branching ratios of hyperon decays in the minimal 331 model are seven times larger than the SM results.The authors are grateful to Profs. Hai-Bo Li and Wei Wang for useful discussions.
Study of the s→dνˉν rare hyperon decays in the Standard Model and new physics
- Received Date: 2019-01-18
- Accepted Date: 2019-05-04
- Available Online: 2019-09-01
Abstract: FCNC processes offer important tools to test the Standard Model (SM) and to search for possible new physics. In this work, we investigate the