ExploringtheΥ(6S) → χ φandΥ(6S) → χ ωhidden-bottomhadronictransitions bJ bJ Qi Huang,∗ Bo Wang,† and Xiang Liu‡ School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China ResearchCenterforHadronandCSRPhysics,LanzhouUniversityandInstituteofModernPhysicsofCAS,Lanzhou730000,China Dian-Yong Chen§ Department of Physics, Southeast University, Nanjing 210094, China Takayuki Matsuki¶ Tokyo Kasei University, 1-18-1 Kaga, Itabashi, Tokyo 173-8602, Japan Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198, Japan In this work, we investigate the hadronic loop contributions to the Υ(6S) → χ φ (J = 0,1,2) along bJ 7 with Υ(6S) → χ ω (J = 0,1,2) transitions. We predict that the branching ratios of Υ(6S) → χ φ, bJ b0 1 Υ(6S) → χ φandΥ(6S) → χ φare(0.68 ∼ 4.62)×10−6,(0.50 ∼ 3.43)×10−6 and(2.22 ∼ 15.18)×10−6, b1 b2 0 respectively and those of Υ(6S) → χ ω, Υ(6S) → χ ω and Υ(6S) → χ ω are (0.15 ∼ 2.81)×10−3, b0 b1 b2 2 (0.63 ∼ 11.68)×10−3 and (1.08 ∼ 20.02)×10−3, respectively. Especially, some typical ratios, which re- flect the relative magnitudes of the predicted branching ratios, are given, i.e., for Υ(6S) → χ φ transi- b bJ tions, Rφ = B[Υ(6S)→χ φ]/B[Υ(6S)→χ φ] ≈ 0.74, Rφ = B[Υ(6S)→χ φ]/B[Υ(6S)→χ φ] ≈ e 10 b1 b0 20 b2 b0 F 3.28, and Rφ = B[Υ(6S)→χ φ]/B[Υ(6S)→χ φ] ≈ 4.43, and for Υ(6S) → χ ω transitions, Rω = 21 b2 b1 bJ 10 8 BRω[Υ(=6SB)[→Υ(6χSb1)ω→]/Bχ[Υω(6]/SB)[→Υ(6χSb0)ω→] χ≈ ω4.]11≈, 1R.72ω02.=WiBth[Υth(6eSr)un→ninχgb2ωof]/BBe[lΥle(I6ISin)→theχnb0eωar]fu≈tur7e.,0e6x,paenrid- 2 21 b2 b1 mentalmeasurementofthesetwokindsoftransitionswillbeapotentialresearchissue. ] h PACSnumbers:14.40.Pq,13.25.Gv p - p I. INTRODUCTION hadronicloopmechanism,whichisanequivalentdescription e ofthecoupledchanneleffect[4–6,8–10,12–16]. Byanalyz- h ingthesetransitions,therelativedecayratesofΥ(6S)→χ φ [ Asaninterestingresearchissue,experimentalstudiesofthe bJ (J = 0,1,2) and Υ(6S) → χ ω (J = 0,1,2), which are a 2 hadronic transitions of Υ(5S) have been focused on by the bJ typical physical quantity given by our calculation, are deter- v Belle Collaboration in the past decade. When surveying the mined. Especially, our results show that these relative decay 4 reported hadronic transitions of Υ(5S), we found their gen- rates are weakly dependent on the model parameters. Thus, 9 eral property, i.e., their observed hadronic transitions have 8 large branching ratios. For example, Belle observed anoma- experimental measurement of these rates can be a crucial 0 lous decay widths of the Υ(5S) → Υ(nS)π+π− [1], and test of the hadronic loop mechanism in the Υ(6S) → χbJφ 0 and Υ(6S) → χ ω decays. In addition, we also estimate Υ(5S) → χ ω (J = 0,1,2) transitions[2]. Inaddition, two bJ . bJ the typical values of the branching ratios of Υ(6S) → χ φ 1 bottomonium-like states Z (10610) and Z (10650) were ob- bJ 0 served in Υ(5S) → Υ(nS)bπ+π− [3]. As inbdicated in a serial and Υ(6S) → χbJω, which can be measured experimentally 7 in near future. Anyway, we would like to inspire experi- of theoretical studies [4–10], the puzzling phenomena hap- 1 menlists’ interest in searching for the Υ(6S) → χ φ and peningonΥ(5S)transitionsreflectanunderlyingmechanism bJ v: mediatedbyacoupledchanneleffectsinceΥ(5S)isabovethe Υ(6S)→χbJωdecaysbyourresultspresentedinthiswork. Xi thresholdsofB((∗s))B¯((∗s))[11]. weTphrisespenaptetrheisdeotragialendizecdalcauslaftoiollnowosf.Υ(A6fSte)r→introχduφctiaonnd, bJ r In the bottomonium family, the Υ(6S) has the similar sit- Υ(6S) → χ ω via the hadronic loop mechanism in Sec. II. a uation to that of Υ(5S). We have a reason to believe that ThenumericbaJlresultsarepresentedinSec.III.Thepaperends the coupled channel effect is still important to the hadronic withashortsummary. transitionsofΥ(6S),whoseexplorationis,thus,anintriguing topic.Thisthemecanprovideusavaluableinformationofthe coupled-channeleffectonthesedecays. II. Υ(6S)→χ φANDΥ(6S)→χ ωTRANSITIONSVIA bJ bJ Inthiswork, wecalculatetheΥ(6S) → χ φ(J = 0,1,2) HADRONICLOOPMECHANISM bJ along with Υ(6S) → χ ω (J = 0,1,2) processes via the bJ Under the hadronic loop mechanism, the Υ(6S)→χ φ bJ transitionsoccurviathetriangleloopscomposedofB(∗)0 and s B¯(∗)0, which play a role of the bridge to connect the initial ∗Electronicaddress:[email protected] staste Υ(6S) and final states φ and χ . In Figs. 1-3, we list †Electronicaddress:[email protected] thetypicaldiagramsdepictingtheΥ(b6JS)→χ φ(J =0,1,2) ‡Electronicaddress:[email protected] bJ §Electronicaddress:[email protected] transitions. For the Υ(6S)→χbJω transitions, due to very ¶Electronicaddress:[email protected] differentquarkcontentsbetweenφandω,thebridgeschange 2 toB(∗) andB¯(∗) andthediagramschangesimultaneouslyasin Figs. 4-6. To calculate these diagrams at the hadron level, we adopt theeffectiveLagrangianapproach,inwhichwefirstintroduce theLagrangiansrelevanttoourcalculation. For the interactions between a heavy quarkonium and two heavy-lightmesons,theLagrangiansareconstructedbasedon theheavyquarkeffectivetheory. Intheheavyquarklimit,the lightdegreesoffreedom s isagoodquantumnumber. Thus, (cid:96) eachvalueof s isassignedtoadoubletformedbythestates (cid:96) with a total angular momentum J = s ±1/2, while for the (cid:96) heavyquarkonium,sincethedegeneracyisexpectedunderthe rotationsoftwoheavyquarkspins,thereisamultipletformed byheavyquarkoniawiththesameangularmomentum(cid:96). FIG.3:SchematicdiagramsdepictingtheΥ(6S)→χ φprocessvia b2 thehadronicloopmechanism. FIG.1:SchematicdiagramsdepictingtheΥ(6S)→χ φprocessvia b0 thehadronicloopmechanism. FIG.4:SchematicdiagramsdepictingtheΥ(6S)→χ ωprocessvia b0 thehadronicloopmechanism. FIG.2:SchematicdiagramsdepictingtheΥ(6S)→χ φprocessvia b1 thehadronicloopmechanism. FIG.5:SchematicdiagramsdepictingtheΥ(6S)→χ ωprocessvia b1 thehadronicloopmechanism. 3 For the interaction between a light vector meson and two heavy-lightmesons,thegeneralformoftheLagrangianreads as[18,22–26] L =iβTr[Hjvµ(−ρ )iH¯ ]+iλTr[HjσµνF (ρ)H¯ ], (5) V µ j i µν i where g ρ = i√V V , (6) µ µ 2 F (ρ) = ∂ ρ −∂ ρ +[ρ ,ρ ], (7) µν µ ν ν µ µ ν andavectoroctetVhastheform V = √12(Kρρ0∗−−+ω) √12(−Kρ¯ρ+∗00+ω) KKφ∗∗+0 . (8) ByexpandingtheLagrangiansinEqs. (1)and(5),thefol- lowingconcreteexpressionsareobtained L ΥB(∗)B(∗) =−igΥBBΥµ(∂µBB†−B∂µB†) ↔ ↔ FIG.6:SchematicdiagramsdepictingtheΥ(6S)→χb2ωprocessvia +gΥB∗Bεµναβ∂µΥν(B∗α ∂β B†−B ∂β B∗α†) thehadronicloopmechanism. ↔ +igΥB∗B∗Υµ(B∗ν∂νB∗µ†−∂νB∗µB∗ν†−B∗ν ∂µ B∗ν†), (9) Therefore, under the framework of heavy quark symme- L try,generalformsofcouplingsbetweenanS-waveorP-wave χbJB(∗)B(∗) heavy quarkonium and two heavy-light mesons can be con- =−g χ BB†−g χ B∗B∗µ† structedas[18] χb0BB b0 χb0B∗B∗ b0 µ +ig χµ (B∗B†−BB∗†) (cid:20) ↔ (cid:21) χc1BB∗ b1 µ µ L = igTr R(QQ¯)H¯(Q¯q)γµ ∂ H¯(Qq¯) +H.c., −g χµν∂ B∂ B† s µ χb2BB b2 µ ν Lp = ig1Tr(cid:104)P(QQ¯)µH¯(Q¯q)γµH¯(Qq¯)(cid:105)+H.c., (1) +gχb2B∗B∗χµb2ν(B∗µB∗ν†+B∗νB∗µ†) −ig ε ∂αχµρ(∂ B∗ν∂βB†−∂βB∂ B∗ν†),(10) in which R(QQ¯) and P(QQ¯) denote multiplets formed by bot- χb2B∗B µναβ b2 ρ ρ tomoniawith(cid:96)=0and(cid:96)=1,andtheirdetailedexpressions, asinRef. [21],canbewrittenas LB(∗)B(∗)V ↔µ R(QQ¯) = 1+v/(cid:104)Υµγ −η γ (cid:105)1−v/, (2) =−igBBVB†i ∂ Bj(Vµ)ij 2 µ b 5 2 ↔α ↔α −2f ε (∂µVν)i(B† ∂ B∗βj−B∗β† ∂ Bj) B∗BV µναβ j i i P(QQ¯)µ = 1+2 v/(cid:104)χµb2αγα+ √12εµαβγvαγβχb1γ +igB∗B∗VB∗iν† ↔∂µ B∗νj(Vµ)ij +4if B∗†(∂µVν−∂νVµ)iB∗j. (11) +√1 (cid:0)γµ−vµ(cid:1)χ +hµγ (cid:105)1−v/, (3) B∗B∗V iµ j ν 3 b0 b 5 2 With the above effective Lagrangians, we can write out the amplitudes of hadronic loop contributions to Υ(6S) → respectively. H(Qq¯)representsadoubletformedbyheavy-light χ φ(J = 0,1,2). FortheΥ(6S) → χ φtransition, theam- pseudoscalarandvectormesons[18–21] bJ b0 plitudescorrespondingtoFig. 1are 1+v/(cid:104) (cid:105) H(Qq¯) = 2 B∗µγµ−Bγ5 , (4) M(0−1) = (cid:90) (d2π4q)4[−igΥBsBs(cid:15)Υµ((ik1)µ−(ik2)µ)] with definitions B(∗)† = (B(∗)+,B(∗)0,B(s∗)0) and B(∗) = ×[−ig (cid:15)∗ ((−ik )λ−(iq)λ)][−g ] (B(∗)−,B¯(∗)0,B¯(∗)0)T as in Ref. [13]. H(Q¯q) corresponds to a BsBsφ φλ 1 BsBsχb0 s 1 1 1 doubletformedbyheavy-lightanti-mesons,whichcanbeob- × F2(q2), (12) tainedbyapplyingthechargeconjugationoperationtoH(Qq¯). k2−m2 k2−m2 q2−m2 1 Bs 2 Bs Bs 4 Then,thepartialdecaywidthreads (cid:90) d4q 1 1 |(cid:126)p | M(0−2) = (2π)4[−gΥB∗sBsεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ΓΥ(6S)→χbJφ = 38πm2φ |MTΥo(6taSl)→χbJφ|2, (17) Υ(6S) ×[2fB∗sBsφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)][−gBsBsχb0] where the overline indicates the sum over polarizations of ×−gσαk+2k−1αmk21σ/m2B∗s k2−1m2 q2−1m2 F2(q2), (13) eΥr(a6gSe)o,vφe,rathnedpχobl1ar(iozratχiobn2)oafnindittihaelΥfa(c6tSor).31 denotes the av- 1 B∗s 2 Bs Bs InthecaseofΥ(6S) → χ ω,theexpressionofthepartial bJ decaywidthisgivenby (cid:90) d4q M(0−3) = (2π)4[gΥBsB∗sεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ΓΥ(6S)→χbJω = 3181πm|2(cid:126)pω| |ATΥo(6taSl)→χbJω|2, (18) ×[−2fBsB∗sφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] Υ(6S) with a general expression of the total amplitude of ×[−gB∗sB∗sχb0]k2−1m2 −gζαk+2k−2αmk22ζ/m2B∗s Υ(6S)→χbJωas (cid:88) 1 Bs 2 B∗s ATotal =4 A (19) −gσ+qσq /m2 Υ(6S)→χbJω (J−j) × ζ ζ B∗sF2(q2), (14) j q2−m2 B∗s byconsideringtheisospinandchargesymmetry.Thedetailed expressionsofA arecollectedinAppendix. (J−j) (cid:90) d4q M(0−4) = (2π)4[igΥB∗sB∗s(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν III. NUMERICALRESULTS −g ((ik ) −(ik ) ))] αβ 2 µ 1 µ ×[(cid:15)φ∗λ(igB∗sB∗sφgδσ((−ik1)λ−(iq)λ) timWatiethththeehafodrrmonuilcasloloisptecdonintriSbeuct.ioInIsatnodthAepΥpe(6nSdi)x,→weχesφ- +4ifB∗sB∗sφ(ip2)ρ(gλδgρσ−gλσgρδ))][−gB∗sB∗sχb0] together with Υ(6S) → χ ω (J = 0,1,2) transitions. BbJe- bJ ×−gαδ +k1δk1α/m2B∗s −gβζ +k2βk2ζ/m2B∗s sides the masses taken from the Particle Data Book [11], all k2−m2 k2−m2 theotherinputparametersweneedarethecouplingconstants. 1 B∗s 2 B∗s Since the Υ(6S) is above the threshold of B(∗)B¯(∗), the cou- −g +q q /m2 (s) (s) × σζ σ ζ B∗sF2(q2), (15) pling constants between Υ(6S) and B((∗s))B¯((∗s)) can be evaluated q2−m2B∗s by the partial decay widths of Υ(6S) → B((∗s))B¯((∗s)). In Table I where p , p and p are momenta of Υ(6S), φ/ω and χ , welisttherelevantpartialdecaywidthsgiveninRef. [27]as 1 2 3 bJ andk ,k ,andqaremomentaofinternal B(∗) andexchanged wellasthecorrespondingextractedcouplingconstants. 1 2 (s) B(∗), respectively. In these expressions of the decay am- (s) plitudes, the monopole form factor is introduced, by which TABLEI:ThecouplingconstantsofΥ(6S)interactingwithB(∗)B¯(∗). (s) (s) the inner structure of interaction vertices is reflected and the Here,wealsolistthecorrespondingpartialdecaywidthsprovidedin off-shell effect of the exchanged bottom-strange mesons is Ref.[27]. compensated. Here, the adopted form factor is taken as Finalstate Decaywidth(MeV) Couplingconstant F(q2) = (m2 − Λ2)/(q2 − Λ2), with m being the mass of BB¯ 1.32 0.654 the exchangeEd boson and the cutoff Λ Ebeing parameterized BB¯∗ 7.59 0.077GeV−1 as Λ = mE + αΛΛQCD with ΛQCD = 0.22 GeV as in Refs. BB∗BB¯¯∗ 1.315.×8910−3 00..601413 [14–16]. We need to specify that the monopole behavior of s s B B¯∗ 0.136 0.023GeV−1 theadoptedformfactorwassuggestedbytheQCDsumrule s s B∗B¯∗ 0.310 0.354 studiedinRef. [17]. Inaserialofpublishedpapers(seeRefs. s s [4–6, 8–10, 12–16, 21, 29]), the monopole form factor was Thecouplingconstantsrelevanttotheinteractionsbetween adoptedtostudythetransitionsofcharmoniaandbottomonia, χ and B(∗)B¯(∗) in the heavy quark limit are related to one and B decays. Thus, this approach has been tested by these bJ (s) (s) gaugecouplingg giveninEq. (1),i.e., successfulstudies. 1 In a similar way, we can further write out the decay am- √ √ 2 √ plitudes of Υ(6S) → χb1φ and Υ(6S) → χb2φ, which are gχb0BB = 2 3g1 mχb0mB, gχb0B∗B∗ = √3g1 mχb0mB∗, collectedinAppendix. Byconsideringtheisospinsymmetry, √ waigtehnJer=al0e,x1p,r2esissiownriottfenthaestotalamplitudeofΥ(6S)→χbJφ gχb1BB∗ = 2√2g1√mχb1mBmB∗, gχb2BB =2g1 mmBχb0, (cid:115) (cid:88) m √ MTotal =2 M . (16) g = g χb2 , g =4g m m , Υ(6S)→χbJφ (J−j) χb2BB∗ 1 m3 m χb2B∗B∗ 1 χb2 B∗ j B∗ B 5 (cid:113) whereg = − mχb0 1 [21]and f = 175±55MeVisthe decayco1nstantof3χ fχ[b028]. χb0 20 B((∗sS))Bi¯m((∗si))lacralny,betheextrcaobc0utpedlinfrgomcoEnqst.a(n5t)s, between φ or ω and 3-10)16 ΥΥΥ(((666SSS)))→→→χχχbbb012ωωω × gBsBsφ = gB∗sB∗sφ = β√g2V, →χω](bJ12 fBsB∗sφ = fmB∗sBB∗s∗sφ = λ√g2V, B6S[Υ() 48 βg g = g = V, BBω B∗B∗ω 2 fBB∗ω = fBm∗B∗ω = λg2V, 0.5 0.6 0.7 αΛ 0.8 0.9 1.0 B∗ with β = 0.9 and λ = 0.56 GeV−1. Additionally, we have FofIGΥ.(68S:)(C→olχoroωn.line). TheαΛ dependenceofthebranchingratios g = m /f along with the pion decay constant f = 132 bJ V ρ π π MeV[22–25]. Withtheabovepreparation,wecanevaluatethebranching ratios of the Υ(6S) → χ φ and Υ(6S) → χ ω transitions. bJ bJ However,inourmodel,therestillexistsafreeparameterαΛ, which is introduced to parameterize the cutoff Λ. Since the 4 cutoff Λ should not be too far from the physical mass of the exchangedmesons[29],inthisworkwesettherange0.65 ≤ 3 αΛ ≤1.15forΥ(6S)→χbJφtransitionsandset0.45≤αΛ ≤ ϕRij 1.15 for Υ(6S) → χ ω transitions to present the numerical Rϕ bJ 2 10 results. Rϕ 20 In Figs. 7 and 8, we illustrate the αΛ dependence of the Rϕ branching ratios of Υ(6S) → χbJφ and Υ(6S) → χbJω, re- 1 21 spectively, and in Figs. 9 and 10 we present the αΛ depen- denceoftherelativemagnitudesamongthebranchingwidths ofΥ(6S)→χ φandΥ(6S)→χ ω,respectively. 0.7 0.8 0.9 1.0 1.1 bJ bJ αΛ FIG. 9: (Color online). The αΛ dependence of the ratios R1φ0 = B[Υ(6S) → χ φ]/B[Υ(6S) → χ φ], Rφ = B[Υ(6S) → b1 b0 20 χ φ]/B[Υ(6S)→χ φ]andRφ =B[Υ(6S)→χ φ]/B[Υ(6S)→ 14 b2 b0 21 b2 Υ(6S)→χb0ϕ χb1φ]. 6-0)12 ΥΥ((66SS))→→χχbb12ϕϕ 1 ×10 ϕ]( χbJ 8 8 → S) 6 6 Υ( Rω B[ 4 6 R1ω0 20 Rω 2 21 ωRij 4 0.7 0.8 0.9 1.0 1.1 αΛ 2 FIG.7: (Coloronline). TheαΛ dependenceofthebranchingratios ofΥ(6S)→χ φ. bJ 0.5 0.6 0.7 0.8 0.9 1.0 αΛ FIG. 10: (Color online). The αΛ dependence of the ratios R1ω0 = B[Υ(6S) → χ ω]/B[Υ(6S) → χ ω], Rω = B[Υ(6S) → b1 b0 20 χ ω]/B[Υ(6S)→χ ω]andRω =B[Υ(6S)→χ ω]/B[Υ(6S)→ b2 b0 21 b2 χ ω]. b1 6 Varying αΛ between 0.65 and 1.15 in Υ(6S) → χbJφ, we BB¯ threshold,wherethecoupled-channeleffectmaybecome havefromFig. 7, important,whichwastestedbythestudiesinRefs. [4–10,12, 13]. Itisobviousthatthisisnottheendofthewholestory. B[Υ(6S)→χb0φ] = (0.68∼4.62)×10−6, If the hadronic loop mechanism is a universal mechanism B[Υ(6S)→χ φ] = (0.50∼3.43)×10−6, existinginhigherbottomoniumtransitions,wehaveareason b1 B[Υ(6S)→χ φ] = (2.22∼15.18)×10−6, to believe that this mechanism also plays an important role b2 in higher bottomonium transitions. Considering the similar- and for αΛ varying from 0.45 to 1.15 in Υ(6S) → χbJω, we ity between Υ(6S) and Υ(5S), where Υ(6S) is the third bot- havefromFig. 8 tomomium with open-bottom channels, we have focused on Υ(6S) → χ φ and Υ(6S) → χ ω hadronic decays. Using bJ bJ B[Υ(6S)→χ ω] = (0.15∼2.81)×10−3, thehadronicloopmechanism,wehaveestimatedthebranch- b0 B[Υ(6S)→χb1ω] = (0.63∼11.68)×10−3, ing ratios of Υ(6S) → χbJφ and Υ(6S) → χbJω, which can reach up to 10−6 and 10−3, respectively. In the near future, B[Υ(6S)→χ ω] = (1.08∼20.02)×10−3. b2 BelleIIwillberunningneartheenergyrangeofΥ(6S),which makes BelleII have a great opportunity to find the χ φ and Inaddition,sometypicalvaluesfortherelativemagnitudes bJ χ ω decay modes of Υ(6S). If these rare decays are ob- of the predicted branching ratios are obtained from Figs. 9 bJ served,thehadronicloopeffectscanbefurthertested. and 10, which are weakly dependent on the free parameter αΛ,i.e., In this work, we have especially obtained six almost sta- ble ratios Rφ , Rφ and Rφ in addition to Rω, Rω and Rω Rφ = B[Υ(6S)→χb1φ] ≈0.74, reflecting th1e0rela2t0ive mag2n1itudes of the Υ(6S10) →20χbJφ an2d1 10 B[Υ(6S)→χ φ] Υ(6S) → χ ω decays, which are weakly dependent on our b0 bJ Rφ = B[Υ(6S)→χb2φ] ≈3.28, model parameter αΛ. Thus, these obtained ratios are impor- 20 B[Υ(6S)→χ φ] tant observable quantities. We have also suggested their ex- b0 B[Υ(6S)→χ φ] perimental measurement, which is also a crucial test of our Rφ = b2 ≈4.43, model. 21 B[Υ(6S)→χ φ] b1 We notice therecent talk of the status ofSuperKEKB and B[Υ(6S)→χ ω] Rω = b1 ≈4.11, the future plan of taking data at the BelleII experiment [30]. 10 B[Υ(6S)→χb0ω] Since the collision data on Υ(6S) will be taken, we need to B[Υ(6S)→χ ω] explore the possible interesting research issues about Υ(6S). Rω = b2 ≈7.06, 20 B[Υ(6S)→χ ω] Ourpresentworkisonlyonesteptowardthelongmarch. b0 B[Υ(6S)→χ ω] Rω = b2 ≈1.72. 21 B[Υ(6S)→χ ω] b1 Acknowledgments As shown in numerical results on the Υ(6S) → χ φ de- bJ cays,thepartialdecaywidthsofΥ(6S)→χ φandΥ(6S)→ b0 This project is supported by the National Natural Sci- χ φ are the same order of magnitude, while the partial de- b1 ence Foundation of China under Grants No. 11222547, caywidthofΥ(6S) → χ φisoneorderofmagnitudelarger b2 No.11175073,No.11375240,andNo.11035006,andbyChi- than those of Υ(6S) → χ φ and Υ(6S) → χ φ. On the b0 b1 nese Academy of Sciences under the funding Y104160YQ0 other hand for the Υ(6S) → χ ω decays, the partial decay bJ andtheagreementNo.2015-BH-02. XLisalsosupportedby widths of Υ(6S) → χ ω and Υ(6S) → χ ω are nearly the b1 b2 theNationalProgramforSupportofYoungTop-notchProfes- same order of magnitude, while the partial decay width of sionals. Υ(6S) → χ φ is one order of magnitude smaller than those b0 ofΥ(6S)→χ ωandΥ(6S)→χ ω. b1 b2 Appendix IV. SUMMARY AsfortheΥ(6S) → χ φtransition,theamplitudescorre- b1 In the past years, the anomalous hadronic transitions like spondingtoFig. 2are Υ(5S) → Υ(nS)π+π− (n = 1,2,3) [1] and Υ(5S) → χ ω bJ (J = 0,1,2) [2] were reported by Belle, which has stimu- (cid:90) d4q latedtheorists’interestinrevealingtheunderlyingmechanism M(1−1) = (2π)4[−igΥBsBs(cid:15)Υµ((ik1)µ−(ik2)µ)] behind these phenomena [4–10]. As a popular and accepted opinion,thehadronicloopmechanismhasbeenappliedtoex- ×[−2fBsB∗sφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] pInlaainddwithioynt,hmeroereexpisrteadnicotmioanlsouresletrvaannstittioonthsefoΥr(Υ5S(5)Str)a[n4s–i1ti0o]n. ×[igBsB∗sχb1(cid:15)χ∗bζ1]k2−1m2 k2−1m2 1 Bs 2 Bs weregiveninRefs. [12,13]. −gσ+q qσ/m2 Themainreasontointroducethehadronicloopmechanism × ζ ζ B∗sF2(q2), (20) isthatΥ(5S)isthesecondobservedbottomoniumabovethe q2−m2 B∗s 7 (cid:90) d4q M(1−2) = (2π)4[−gΥB∗sBsεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] (cid:90) d4q ×[(cid:15)φ∗λ(igB∗sB∗sφgδσ((−ik1)λ−(iq)λ) M(2−3) = (2π)4[−gΥB∗sBsεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] +4ifB∗sB∗sφ(ip2)ρ(gλδgρσ−gλσgρδ))] ×[2fB∗sBsφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] −g +k k /m2 ×[−g (cid:15)∗ζη(−iq) (−ik ) ] ×[igBsB∗sχb1(cid:15)χ∗bζ1] αδk12−1αm2B1δ∗s B∗s ×−gσαBs+Bskχb12αkχ1σb2/m2B∗s ζ 1 2 η 1 F2(q2),(26) × 1 −gσζ +qσqζ/m2B∗sF2(q2), (21) k12−m2B∗s k22−m2Bs q2−m2Bs k2−m2 q2−m2 2 Bs B∗s (cid:90) d4q M(1−3) = (2π)4[gΥBsB∗sεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] (cid:90) d4q ×[−igBsBsφ(cid:15)φ∗λ((−ik1)λ−(iq)λ)] M(2−4) = (2π)4[−gΥB∗sBsεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ×[−igB∗sBsχb1(cid:15)χ∗bζ1]k12−1m2Bs ×+[4(cid:15)iφ∗fλB(∗siBg∗sBφ∗(sBip∗sφ2g)ρδσ(g((λ−δgikρσ1)−λ−gλ(σiqg)ρλδ)))] ×−gαζ +k2αk2ζ/m2B∗s 1 F2(q2), (22) ×[−igBsB∗sχb2εζωκξ(cid:15)χ∗bζ2η(ip3)κ(−iq)η(−ik2)ξ] k22−m2B∗s q2−m2Bs ×−gαδ−k1αk1δ/m2B∗s 1 k2−m2 k2−m2 M(1−4) = (cid:90) (d2π4q)4[igΥB∗sB∗s(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν ×−gωσ+1qσqωB/∗sm2B∗sF22(q2), Bs (27) q2−m2 −gαβ((ik2)µ−(ik1)µ))] B∗s ×[2fB∗sBsφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] −gασ+kαkσ/m2 ×[−igB∗sBsχb1(cid:15)χ∗bζ1] k2−1m21 B∗s 1 B∗s (cid:90) ×−gβζ +k2ζk2β/m2B∗s 1 F2(q2). (23) M(2−5) = (d2π4q)4[gΥBsB∗sεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] k2−m2 q2−m2 2 B∗s Bs ×[−igBsBsφ(cid:15)φ∗λ((−ik1)λ−(iq)λ)] spoAnsdifnogrtthoeFΥig(.63S)ar→e χb2φtransition,theamplitudescorre- ×[igB∗sBsχb2εζωκξ(cid:15)χ∗bζ2η(ip3)κ(−iq)ξ(−ik2)η] (cid:90) d4q × 1 −gωα +k2αk2ω/m2B∗s M(2−1) = (2π)4[−igΥBsBs(cid:15)Υµ((ik1)µ−(ik2)µ)] k12−m2Bs k22−m2B∗s 1 ×[−ig (cid:15)∗ ((−ik )λ−(iq)λ)] × F2(q2), (28) BsBsφ φλ 1 q2−m2 ×[−g (cid:15)∗ζη(−iq) (−ik ) ] Bs BsBsχb2 χb2 ζ 2 η 1 1 1 × F2(q2), (24) k2−m2 k2−m2 q2−m2 1 Bs 2 Bs Bs (cid:90) (cid:90) d4q M(2−2) = (d2π4q)4[−igΥBsBs(cid:15)Υµ((ik1)µ−(ik2)µ)] M(2−6) = (2π)4[gΥBsB∗sεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ×[−2fBsB∗sφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] ×[−2fBsB∗sφελρδσ(cid:15)φ∗λ(ip2)ρ((−ik1)δ−(iq)δ)] ××[−ig1BsB∗sχb2εζω1κξ(cid:15)χ∗bζ2η(ip3)κ(−iq)η(−ik2)ξ] ××[gB∗s1B∗sχb2(cid:15)χ∗−bζ2ηg(καg+ζκgkη2ξαk+2κ/gmηκ2Bg∗sζξ)] k2−m2 k2−m2 k2−m2 k2−m2 1 Bs 2 Bs 1 Bs 2 B∗s −gσω+qσqω/m2 −gσξ+qσqξ/m2 × B∗sF2(q2), (25) × B∗sF2(q2), (29) q2−m2 q2−m2 B∗s B∗s 8 M(2−7) = (cid:90) (d2π4q)4[igΥB∗sB∗s(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν A(0−4) = (cid:90) (d2π4q)4[igΥB∗B∗(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν −gαβ((ik2)µ−(ik1)µ))] −gαβ((ik2)µ−(ik1)µ))] ××[[2igfBB∗s∗sBBssχφbε2ελρζδωσκξ(cid:15)(cid:15)φ∗χλ∗bζ(2ηi(pi2p)3ρ)(κ((−−iikq1))ξδ(−−i(ki2q))ηδ])]] +×4[−(cid:15)iωg∗fλBα(∗+iBg∗ωBk∗(Bip∗kω2αg)/ρδm(σg2(λ(δ−−giρkgσ1β)ζ−λ+−gkλ(σβikqgζ)ρ/λδ)m))]2[−gB∗B∗χb0] −gασ+kαkσ/m2 −gβω+kβkω/m2 × δ 1δ 1 B∗ 2 2 B∗ × 1 1 B∗s 2 2 B∗s k2−m2 k2−m2 k2−m2 k2−m2 1 B∗ 2 B∗ 1 B∗s 2 B∗s −g +q q /m2 1 × σζ σ ζ B∗F2(q2). (35) × F2(q2), (30) q2−m2 q2−m2 B∗ Bs AsfortheΥ(6S) → χ ωtransition,theamplitudescorre- b1 spondingtoFig. 5are (cid:90) M(2−8) = (d2π4q)4[igΥB∗sB∗s(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν A(1−1) = (cid:90) (d2π4q)4[−igΥBB(cid:15)Υµ((ik1)µ−(ik2)µ)] −g ((ik ) −(ik ) ))] αβ 2 µ 1 µ ×[−2f ε (cid:15)∗λ(ip )ρ((−ik )δ−(iq)δ)] ×[(cid:15)φ∗λ(igB∗sB∗sφgδσ((−ik1)λ−(iq)λ) BB∗ω λρδσ ω1 2 1 1 +4ifB∗sB∗sφ(ip2)ρ(gλδgρσ−gλσgρδ))] ×[igBB∗χb1(cid:15)χ∗bζ1]k12−m2Bk22−m2B ××[−ggBαδ∗sB+∗sχbk21(cid:15)δχ∗kbζ2η1α(/gmζκ2Bg∗sη−ξg+βκgη+κgkζ2βξk)2κ]/m2B∗s ×−gσζq+2−qζmqσ2B/∗m2B∗F2(q2), (36) k2−m2 k2−m2 1 B∗s 2 B∗s (cid:90) ×−gξσ+qσqξ/m2B∗sF2(q2). (31) A(1−2) = (d2π4q)4[−gΥB∗Bεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] q2−m2 B∗s ×[(cid:15)∗ (ig gδσ((−ik )λ−(iq)λ) ωλ B∗B∗ω 1 AsfortheΥ(6S) → χb0ωtransition,theamplitudescorre- +4ifB∗B∗ω(ip2)ρ(gλδgρσ−gλσgρδ))] spondingtoFig. 5are −g +k k /m2 ×[ig (cid:15)∗ζ ] αδ 1α 1δ B∗ A(0−1) = (cid:90) (d2π4q)4[−igΥBB(cid:15)Υµ((ik1)µ−(ik2)µ)] × B1B∗χb1 −χbg1σζ +qkσ12qζ−/mm2B2B∗∗F2(q2), (37) ×[−ig (cid:15)∗ ((−ik )λ−(iq)λ)][−g ] k2−m2 q2−m2 BBω ωλ 1 BBχb0 2 B B∗ 1 1 1 × F2(q2), (32) (cid:90) k2−m2 k2−m2 q2−m2 d4q 1 B 2 B B A(1−3) = (2π)4[gΥBB∗εµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] (cid:90) d4q ×[−igBBω(cid:15)ω∗λ((−ik1)λ−(iq)λ)] A(0−2) = (2π)4[−gΥB∗Bεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ×[−igB∗Bχb1(cid:15)χ∗bζ1]k2−1m2 ×[2f ε (cid:15)∗λ(ip )ρ((−ik )δ−(iq)δ)][−g ] 1 B ×−gσαB∗+Bωk1λαρkδσ1σ/ωm2B∗ 2 1 1 1 F2(q2)B,B(χ3b03) ×−gαζk+2k−2αmk22ζ/m2B∗ q2−1m2F2(q2), (38) k2−m2 k2−m2 q2−m2 2 B∗ B 1 B∗ 2 B B (cid:90) d4q (cid:90) d4q A(1−4) = (2π)4[igΥB∗B∗(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν A(0−3) = (2π)4[gΥBB∗εµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] −gαβ((ik2)µ−(ik1)µ))] ×[−2fBB∗ωελρδσ(cid:15)ω∗λ(ip2)ρ((−ik1)δ−(iq)δ)] ×[2fB∗Bωελρδσ(cid:15)ω∗λ(ip2)ρ((−ik1)δ−(iq)δ)] ×[−gB∗B∗χb0]k2−1m2 −gζαk+2k−2αmk22ζ/m2B∗ ×[−igB∗Bχb1(cid:15)χ∗bζ1]−gασk2+−k1αmk21σ/m2B∗ 1 B 2 B∗ 1 B∗ ×−gσζ +qσqζ/m2B∗F2(q2), (34) ×−gβζ +k2ζk2β/m2B∗ 1 F2(q2). (39) q2−m2 k2−m2 q2−m2 B∗ 2 B∗ B 9 AsfortheΥ(6S) → χ ωtransition,theamplitudescorre- b2 spondingtoFig. 6are (cid:90) d4q (cid:90) d4q A(2−6) = (2π)4[gΥBB∗εµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] A(2−1) = (2π)4[−igΥBB(cid:15)Υµ((ik1)µ−(ik2)µ)] ×[−2f ε (cid:15)∗λ(ip )ρ((−ik )δ−(iq)δ)] BB∗ω λρδσ ω 2 1 ×[−igBBω(cid:15)ω∗λ((−ik1)λ−(iq)λ)] ×[gB∗B∗χb2(cid:15)χ∗bζ2η(gζκgηξ+gηκgζξ)] ×[−gBBχb2(cid:15)χ∗bζ2η(−iq)ζ(−ik2)η] × 1 −gκα+k2αk2κ/m2B∗ × 1 1 1 F2(q2), (40) k12−m2B k22−m2B∗ k12−m2Bk22−m2Bq2−m2B −gσξ+qσqξ/m2 × B∗F2(q2), (45) q2−m2 (cid:90) B∗ d4q A(2−2) = (2π)4[−igΥBB(cid:15)Υµ((ik1)µ−(ik2)µ)] (cid:90) d4q ×[−2fBB∗ωελρδσ(cid:15)ω∗λ(ip2)ρ((−ik1)δ−(iq)δ)] A(2−7) = (2π)4[igΥB∗B∗(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν ×[−igBB∗χb2εζωκξ(cid:15)χ∗bζ2η(ip3)κ(−iq)η(−ik2)ξ] −gαβ((ik2)µ−(ik1)µ))] × 1 1 ×[2fB∗Bωελρδσ(cid:15)ω∗λ(ip2)ρ((−ik1)δ−(iq)δ)] k−12g−σωm+2Bqkσ22q−ω/mm2B2 ×[igB∗Bχb2εζωκξ(cid:15)χ∗bζ2η(ip3)κ(−iq)ξ(−ik2)η]] × B∗F2(q2), (41) −gασ+kαkσ/m2 −gβω+kβkω/m2 q2−m2 × 1 1 B∗ 2 2 B∗ B∗ k2−m2 k2−m2 1 B∗ 2 B∗ 1 (cid:90) × F2(q2), (46) A(2−3) = (d2π4q)4[−gΥB∗Bεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] q2−m2B ×[2fB∗Bωελρδσ(cid:15)ω∗λ(ip2)ρ((−ik1)δ−(iq)δ)] (cid:90) d4q ×[−gBBχb2(cid:15)χ∗bζ2η(−iq)ζ(−ik2)η] A(2−8) = (2π)4[igΥB∗B∗(cid:15)Υµ(gναgµβ(ik2)ν−gµαgνβ(ik1)ν ×−gσα +k1αk1σ/m2B∗ 1 1 F2(q2), (42) −gαβ((ik2)µ−(ik1)µ))] k2−m2 k2−m2 q2−m2 ×[(cid:15)∗ (ig gδσ((−ik )λ−(iq)λ) 1 B∗ 2 B B ωλ B∗B∗ω 1 +4if (ip ) (gλδgρσ−gλσgρδ))] B∗B∗ω 2 ρ A(2−4) = (cid:90) (d2π4q)4[−gΥB∗Bεµναβ(cid:15)Υµ(−ip1)ν((ik2)β−(ik1)β)] ×[−ggBα∗B+∗χbk2(cid:15)χ∗kbζ2ηα(/gmζκ2gη−ξg+βκgη+κgkζβξk)κ]/m2 ×[(cid:15)ω∗λ(igB∗B∗ωgδσ((−ik1)λ−(iq)λ) × δk2−1δm12 B∗ k2−2m22 B∗ 1 B∗ 2 B∗ +4if (ip ) (gλδgρσ−gλσgρδ))] B∗B∗ω 2 ρ −gξ +q qξ/m2 ×[−ig ε (cid:15)∗ζη(ip )κ(−iq) (−ik )ξ] × σ σ B∗F2(q2). 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