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New physics effects to the lepton polarizations in the B - K l^+ l^- decay

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a rXiv:h ep-ph/1339v13Mar21New physics effects to the lepton polarizations in the B →Kℓ+ℓ−decay T.M.Aliev ∗,M.K.C ¸akmak ,A.¨Ozpineci †,M.Savcı‡Physics Department,Middle East Technical University 06531Ankara,Turkey Abstract Using the general,model independent form of the effective Hamiltonian,the gen-eral expressions of the longitudinal,normal and transversal polarization asymmetries for ℓ−and ℓ+and combinations of them for the exclusive B →Kℓ+ℓ−decay are found.The sensitivity of lepton polarizations and their combinations on new Wilson coefficients are studied.It is found that there exist regions of Wilson coefficients for which the branching ratio coincides with the Standard Model result while the lepton polarizations differ substantially from the standard model prediction.Hence,studying lepton polarization in these regions of new Wilson coefficients can serve as a promising tool for establishing new physics beyond the Standard Model.PACS numbers:12.60.–i,13.20.–v,13.25.Hw1IntroductionThe two B meson factories BaBar and Belle,which have already started operation,open an exciting new era in studying physics of B mesons.Both factories have already presented thrilling results on CP violation[1].The physics program of the B factories contain two main directions:detailed study of CP violation in B d decays and precise measurement of rare Flavor Changing Neutral Current(FCNC)processes.It is well known that FCNC processes are very sensitive to the new physics beyond the Standard Model(SM).So,main goal of the investigations undergoing at B factories is tofind inconsistencies within the SM, in particularfind indications for new physics in theflavor and CP violating sector[2].New physics effects can appear in rare B meson decays in two different ways,either through new contributions to the Wilson coefficients existing in the SM or through the new structures in the effective Hamiltonian which are absent in the SM.Rare B meson decays induced by b→s(d)ℓ+ℓ−transition has been extensively studied in framework of the SM and its various extensions[3]–[19].One of the efficient ways in establishing new physics beyond the SM is the measurement of the lepton polarization[19]–[26].All previous studies for the lepton polarization have been limited to SM and its minimal extensions,except the works [23,26].In[23]the analysis of theτlepton polarization for the inclusive b→sτ+τ−decay was presented in a model independent way and in[26]lepton polarizations are investigated using the most general model independent Hamiltonian for the B→K∗ℓ+ℓ−decay.The aim of this work is studying lepton polarizations in the exclusive B→Kℓ+ℓ−decay using the general form of the effective Hamiltonian including all possible form of interactions.Here we will studyµandτleptonic modes because of the following two reasons.Firstly,the electron polarization is hard to measure experimentally,and secondly, it is well known that in the SM the normal P N and transversal P T polarizations are both proportional to the lepton mass and hence their measurements might be possible especially in theτ−τ+channel.The work is organized as follows.In section2,using a general form of four–Fermi interaction we derive the general expressions for the longitudinal,transversal and normal polarizations of leptons.In section3we investigate the sensitivity of the above–mentioned polarizations to the new Wilson coefficients.At the end of this section we also present our conclusion.2Calculation of lepton polarizationsIn this section we compute the lepton polarization asymmetries,using the most general, model independent form of the effective Hamiltonian.The effective Hamiltonian for the b→sℓ+ℓ−transition in terms of twelve model independent four–Fermi interactions can be written in the following form:H eff=G Fα2πV ts V∗tb C SL¯s iσµνqνq2R b¯ℓγµℓ+C tot LL¯s Lγµb L¯ℓLγµℓL+C tot LR¯s Lγµb L¯ℓRγµℓR+C RL¯s Rγµb R¯ℓLγµℓL+C RR¯s Rγµb R¯ℓRγµℓR+C LRLR¯s L b R¯ℓLℓR+C RLLR¯s R b L¯ℓLℓR(1)+C LRRL¯s L b R¯ℓRℓL+C RLRL¯s R b L¯ℓRℓL+C T¯sσµνb¯ℓσµνℓ+iC T Eǫµναβ¯sσµνb¯ℓσαβℓ ,where the chiral projection operators L and R in(1)are defined asL=1−γ52,and C X are the coefficients of the four–Fermi interactions and q=p B−p K is the momentum transfer.Note that among twelve Wilson coefficients several already exist in the SM.Thecoefficients C SL and C BR correspond to−2m s C eff7and−2m b C eff7in the SM,respectively.The next four terms in Eq.(1)are the vector type interactions with coefficients C tot LL,C tot LR, C RL and C RR.Two of these vector interactions containing C tot LL and C tot LR do exist in the SM as well in the form(C eff9−C10)and(C eff9+C10).Therefore we can say that C tot LL and C tot LR describe the sum of the contributions from SM and the new physics and they can be written asC tot LL=C eff9−C10+C LL,C tot LR=C eff9+C10+C LR,The terms with coefficients C LRLR,C RLLR,C LRRL and C RLRL describe the scalar type interactions.The last two terms with the coefficients C T and C T E,obviously,describe the tensor type interactions.Exclusive B→Kℓ+ℓ−decay is described by the matrix element of effective Hamiltonian over B and K meson states,which can be parametrized in terms of form factors.It follows from Eq.(1)that in order to calculate the amplitude of the B→Kℓ+ℓ−decay,the following matrix elements are neededK|¯sγµb|B ,K|¯s iσµνqνb|B ,K|¯s b|B ,K|¯sσµνb|B .These matrix elements are defined as follows:K(p K)|¯sγµb|B(p B) =f+ (p B+p K)µ−m2B−m2K q2qµ,(2) with f+(0)=f0(0),K(p K)|¯sσµνb|B(p B) =−i f Tm b−m s,(4) K(p K)|¯s iσµνqνb|B(p B) =f TTaking into account Eqs.(1–4),the matrix element of the B→Kℓ+ℓ−decay can be written asM(B→Kℓ+ℓ−)=G Fα2πV tb V∗ts ¯ℓγµℓ A(p B+p K)µ+Bqµ+¯ℓγµγ5ℓ C(p B+p K)µ+Dqµ +¯ℓℓQ+¯ℓγ5ℓN+4¯ℓσµνℓ(−iG) (p B+p K)µqν−(p B+p K)νqµ+4¯ℓσαβℓǫµναβH (p B+p K)µqν−(p B+p K)νqµ .(6) The auxiliary functions above are defined asf TA=(C tot LL+C tot LR+C RL+C RR)f++2(C BR+C SL)(m2B−m2K),(m B+m K)q2C=(C tot LR+C RR−C tot LL−C RL)f+,D=(C tot LR+C RR−C tot LL−C RL)f−,(7)m2B−m2KQ=f0m b−m s(C LRLR+C RLLR−C LRRL−C RLRL),C TG=f T,m B+m Kwheref−=(f0−f+)m2B−m2K,| p−|S−µN≡(0, e−N)= 0, p K× p−S+µL≡(0, e+L)= 0, p+| p K× p+| ,S+µT≡(0, e+T)= 0, e+N× e+L ,where p∓and p K are the three momenta ofℓ∓and K meson in the center of mass(CM) frame of theℓ+ℓ−system,respectively.The longitudinal unit vectors S−L and S+L are boosted to CM frame ofℓ+ℓ−by Lorentz transformation,S−µL,CM= | p−|mℓ| p−| ,S+µL,CM= | p−|mℓ| p−| ,(9)while vectors S N and S T are not changed by boost.The differential decay rate of the B→Kℓ+ℓ−decay for any spin direction n(∓)of the ℓ(∓),where n(∓)is the unit vector in theℓ(∓)rest frame,can be written asdΓ( n(∓))2 dΓdq2 0=G2Fα21−4m2ℓ/q2 is the lepton velocity.The explicit form of∆is∆=−128λm4B mℓRe(AG∗)+32m2B m2ℓ(1−r)Re(CD∗)+16m2B mℓ(1−r)Re(CN∗) +16m2B m2ℓs|D|2+4m2B s|N|2+16m2B mℓs Re(DN∗)+10243λm4B s(3−v2)|A|2+2563m4B s 2λ−(1−v2) 2λ−3(1−r)2 |C|2. The polarizations P L,P N and P T are defined as:P(∓) i (q2)=dΓdq2( n(∓)=− e(∓)i) dq2( n(∓)= e(∓)i)+dΓwhere P(∓)represents the charged leptonℓ(∓)polarization asymmetry for i=L,N,T,i.e., P L and P T are the longitudinal and transversal asymmetries in the decay plane,respectively, and P N is the normal component to both of them.With respect to the direction of the lepton polarization,P L and P T are P–odd,T–even,while P N is P–even,T–odd and CP–odd.calculations lead to the following results for the longitudinal,transversal and normal polarization of theℓ(∓):P(∓) L =4m2B v3λm2B Re(AC∗)∓643λm2B mℓRe(AH∗)−4mℓ(1−r)Re(CQ∗)+256sλs mℓ(1−r)Re(AC∗)∓64sλJ/ψfamily,but in this work we consider only short distance contributions.Experimentaldata on B(B→X sγfixes only the modulo of C eff7.For this reason throughout our analysiswe have considered both possibilities,i.e.,C eff7=∓0.313,where the upper sign correspondsto the SM prediction.For the values of the form factors,we have used the results of[27](see also[28,29]). The q2dependence of the form factors can be represented in terms of three parameters asF(s)=F(0)exp(c1s+c2s2+c3s3),(15) where the values of parameters F(0),c1,c2and c3for the B→K decay are listed in Table 1.F(0)1.4650.6331.478c20.7820.5910.700Table1:Central values of the parameters for the parametrization(15)of the B→K decay form factors.From the expressions of the lepton polarizations we see that they all depend on q2and the new Wilson coefficients.It may be experimentally difficult to study the dependence of the the polarizations of each lepton on both quantities.Therefore we eliminate the dependence of the lepton polarizations on q2,by performing integration over q2in the allowed kinematical region,so that the lepton polarizations are averaged.The averaged lepton polarizations are defined asP i = (m b−m K)24m2ℓP id B (m b−m K)24m2ℓd BP −L +P +L=0at C X =0,which confirms the SM result as expected.For the otherchoice of C eff 7,i.e.,C eff 7=0.313the situation is similar to the previous case,but the magnitude of P −L +P +Lis smaller.Figs.(3)and (4)are the same as Figs.(1)and (2)but for the B →Kτ+τ−decay.In this case the difference of the dependence of the longitudinal polarization P −L on new Wilson coefficients from the muon case is as follows:In the muon case P −L is negative for all values of the new Wilson coefficients while for the tau case P −L can receive both values,for example for C T <1, P −L is positive,and for C T >1, P −Lis negative.It is obvious from Fig.(4)that if the values of the new Wilson coefficients C LRRL ,C LRLR ,C RLLR ,C RLRL and C T E are negative (positive), P −L +P +L is negative (positive).Absolutely similar situation takes place for C eff 7>0.For these reasons determination of the sign and of course magnitude of P −L +P +L can give promising information about new physics.In Figs.(5)and (6)the dependence of the average transversal polarization P −T and the combination P −T −P +T on the new Wilson coefficients are presented for the B →Kµ+µ−decay,respectively.We observe from Fig.(5)that the average transversal polarization is strongly dependent only on C LRRL and C RLRL and quite weakly to remaining Wilson coef-ficients.It is alsointeresting to note that for the negative (positive)values of these scalar coefficients P −T is negative (positive).For the P −T −P +T case,there appears strong dependence on all four scalar interactions with coefficients C LRRL ,C RLLR ,C LRLR ,C RLRL .The behavior of this combined average transversal polarization is identical for the coeffi-cients C LRLR ,C RLLR and C LRRL ,C RLRL in pairs,so that four lines responsible for these interactions appear only to be two.Moreover P −T −P +T is negative (positive)for the negative (positive)values of the new Wilson coefficients C LRRL and C RLRL and positive (negative)for the coefficients C LRLR and C RLLR .Remembering that in SM,in masslesslepton case P −T ≈0and P −T −P +T ≈0.Therefore determination of the signs and mag-nitudes ofP −T and P −T −P +T can give quite a useful information about the existence of new physics.For the choice of C eff 7=0.313,apart from the minor differences in their magnitudes,the behaviors of P −T and P −T −P +T are similar as in the previous case.As is obvious from Figs.(7)and (8),P −T and P −T −P +T show stronger dependence only on C T for the B →Kτ+τ−decay.Again P −T and P −T −P +T change sign at C T ≈−1.As has already been noted,determination of the sign and magnitude of P −T and P −T −P +T are useful hints in looking for new physics.Note that for simplicity all new Wilson coefficients in this work are assumed to be real.Under this condition P −N and P −N +P +N have non-vanishing values coming from the imaginary part of SM,i.e.,from C eff 9.From Figs.(9)and (10)we see thatP −N andP −N +P +N are strongly dependent on all scalar type interactions for the B →Kµ+µ−decay.Similar behavior takes place for the B →Kτ+τ−decay as well.The change in sign and magnitude of both P −N and P −N +P +N that are observed in these figures is an indication of the fact that an experimental verification of them can give unambiguousinformation about new physics.In the present work we analyze the possibility of pinning down new physics beyond SMby studying lepton polarizations only.It follows from Eq.(11)that the branching ratio of the B→Kℓ+ℓ−decay depends also on the new Wilson coefficients and hence we expect that it can give information about new physics.In this connection there follows the question:Can one establish new physics by studying the lepton polarizations only?In other words, are there regions of the new Wilson coefficients C X in which the value of the branching ratio coincides with that of the SM prediction,but the lepton polarizations would not?In orderto answer this question,we present in Figs.(11)–(14)the dependence of the branching ratio on the average and combined average polarizations of the leptons.In thesefigures thevalue of the branching ratio ranges between the values10−7≤B(B→Kτ+τ−)≤5×10−7. Thesefigures depict that there indeed exist such regions of C X in which the value of the branching ratio does agree with the SM result,while the lepton polarizations differ fromthe SM prediction.It follows from the pair of Figs.(3),(11);(7),(13)and(8),(14),that if C T lies in the region−2≤C T≤0,the above–mentioned condition,i.e.,mismatch of the polarizations in the standard model and the new physics,is fulfilled.On the other hand one can immediately see from Fig.(12)that such a region for the combined average longitudinal lepton polarization does not exist and hence it is not suitable in search of new physics.Note that in allfigures intersection point of all curves correspond to the SM case.This analysis allows us to conclude that there exists certain regions of new Wilson coefficients for which study of the lepton polarization itself can give promising information about new physics.Finally,a few words about the detectibilty of the lepton polarization asymmetries at Bfactories or future hadron colliders,are in order.As an estimation,we choose the averaged values of the longitudinal polarization of muon and transversal and normal polarizations of theτlepton,which are approximately close to the SM prediction,i.e., P L ≃−0.9, P T ≃0.6and P N ≃−0.01.Experimentally,to measure an asymmetry P i of a decay with the branching ratio B at the nσlevel,the required number of events is given by the formula N=n2/(B P i 2.It follows from this expression that to observe the lepton polarizations P L , P T and P N in B→Kτ+τ−decay at1σlevel,the expected number of events are N=(1;3;104)×107,respectively.On the other hand,The number of B¯B pairs that is expected to be produced at B factories is about N∼5×108.A comparison of these numbers allows us to conclude that while measurement of the normal polarization of theτlepton is impossible,measurements of the longitudinal polarization of muon and transversal polarization ofτlepton could be accessible at B factories.References[1]B.Aubert et al.,BaBar Collaboration,preprint:hep–ex/0102030(2001);A.Abashian et al.,BELLE Collaboration,preprint:hep–ex/0102018(2001).[2]Y.Grossman,preprint:hep-ph/0012216(2000).[3]T.Goto,Y.Okada,Y.Shimizu and M.Tanaka,Phys.Rev.D55(1997)4273;T.Goto,Y.Okada,Y.Shimizu and M.Tanaka,Phys.Rev.D58(1998)094006.[4]J.L.Hewett and J.D.Wells,Phys.Rev.D55(1997)5549.[5]Y.Grossman,Z.Ligeti and E.Nardi,Phys.Rev.D55(1997)2768.[6]T.G.Rizzo,Phys.Rev.D58(1998)114014.[7]E.Lunghi,A.Masiero,I.Scimemi and L.Silvestini,Nucl.Phys.B568(2000)120.[8]W.-S.Hou,R.S.Willey and A.Soni,Phys.Rev.Lett.58(1987)1608.[9]N.G.Deshpande and J.Trampetic,Phys.Rev.Lett.60(1988)2583.[10]C.S.Lim,T.Morozumi and A.I.Sanda,Phys.Lett.B218(1989)343.[11]B.Grinstein,M.J.Savage and M.B.Wise,Nucl.Phys.B319(1989)271.[12]W.Jaus and D.Wyler,Phys.Rev.D41(1990)3405.[13]P.J.O’Donnell and H.K.Tung,Phys.Rev.D43(1991)2067.[14]A.Ali,T.Mannel and T.Morozumi,Phys.Lett.B273(1991)505.[15]C.Greub,A.Ioannissian and D.Wyler,Phys.Lett.B346(1995)145.[16]G.Burdman,Phys.Rev.D52(1995)6400.[17]A.J.Buras and M.M¨u nz,Phys.Rev.D52(1995)186.[18]N.G.Deshpande,X.-G.He and J.Trampetic,Phys.Lett.B367(1996)362.[19]T.M.Aliev,M.Savcı,Phys.Lett.B452(1999)318;T.M.Aliev,A.¨Ozpineci,H.Koru and M.Savcı,Phys.Lett.B410(1997)216;T.M.Aliev,C.S.Kim and Y.G.Kim,Phys.Rev.D62(2000)014026.[20]Y.G.Kim,P.Ko and J.S.Lee,Nucl.Phys.B544(1999)64.[21]J.L.Hewett,Phys.Rev.D53(1996)4964.[22]F.Kr¨u ger and L.M.Sehgal,Phys.Lett.B380(1996)199.[23]S.Fukae,C.S.Kim and T.Yoshikawa,Phys.Rev.D61(2000)074015.[24]T.M.Aliev,M.Savcı,Phys.Lett.B481(2000)275.[25]Qi–Shu Yan,Chao–Shang Huang,Liao Wei,Shou–Hua Zhu,Phys.Rev.D62(2000)094023.[26]T.M.Aliev,K.C¸akmak,M.Savcı,preprint:hep–ph/0009133(2000).[27]A.Ali,P.Ball,L.T.Handoko and G.Hiller,Phys.Rev.D61(2000)074024.[28]T.M.Aliev,A.¨Ozpineci,M.Savcı,H.Koru,Phys.Lett.B400(1997)194.[29]V.M.Belyaev,A.Khodjamirian,R.R¨u ckl,Z.Phys.C60(1993)349.[30]P.Ball,JHEP9809(1998)005.Figure captionsFig.(1)The dependence of the average longitudinal polarization asymmetry P−L of muon on the new Wilson coefficients.Fig.(2)The dependence of the combined average longitudinal polarization asymmetry P−L+P+L ofℓ−andℓ+on the new Wilson coefficients for the B→Kµ−µ+decay. Fig.(3)The same as in Fig.(1),but for the B→Kτ−τ+decay.Fig.(4)The same as in Fig.(2),but for the B→Kτ−τ+decay.Fig.(5)The same as in Fig.(1),but for the average transversal polarization asym-metry P−T of muon.Fig.(6)The same as in Fig.(2),but for the transversal polarization asymmetry P−T−P+T .Fig.(7)The same as in Fig.(5),but for the B→Kτ−τ+decay.Fig.(8)The same as in Fig.(6),but for the B→Kτ−τ+decay.Fig.(9)The dependence of the average normal asymmetry P−N of muon on the new Wilson coefficients.Fig.(10)The dependence of the combined average normal polarization asymmetry P−N+P+N on the new Wilson coefficients for the B→Kµ−µ+decay.Fig.(11)Parametric plot of the correlation between the integrated branching ratio B (in units of10−7)and the average longitudinal lepton polarization asymmetry P−L as function of the new Wilson coefficients as indicated in thefigure,for the B→Kτ−τ+ decay.Fig.(12)The same as in the Fig.(11),but for the combined average longitudinal lepton polarization asymmetry P−L+P+L .Fig.(13)The same as in Fig.(11),but for the average transversal lepton polariza-tion asymmetry P−T .Fig.(14)The same as in the Fig.(13),but for the combined average transversal lepton polarization asymmetry P−T−P+T .Figure1: Figure2:Figure3: Figure4:Figure5: Figure6:Figure7: Figure8:Figure9: Figure10:Figure11: Figure12:Figure13: Figure14:。

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New Physics at LEP2

New Physics at LEP2

a r X i v :h e p -p h /9709378v 1 17 S e p 1997New physics at LEP21Ramon Miquel 2Dept.ECM and IFAE Univ.de Barcelona,Facultat de F´ısica Diagonal 647,E-08028Barcelona (Spain)Abstract.Searches for new physics in the first year of run-ning of LEP2,at energies of 161and 172GeV,are summarized.After a short review of WW results and their implications on new physics,searches for the Higgs boson and SUSY particles,analyses of four-jet final states and constraints on possible ex-planations for the HERA high Q 2anomaly are discussed in turn.1.Introduction The second phase of LEP,LEP2,designed to run at energies above the W-pair production threshold started operation in 1996,with two short runs,one at a center-of-mass energy of 161GeV and another at about 172GeV.The four LEP experiments,ALEPH,DELPHI,L3and OPAL,collected about 10pb −1of luminosity each in each of the two runs.The main purpose of the 161GeV run was to measure the W-pair production cross section very close to threshold.This cross section is very sensitive to the value of the W mass and it provides a measurement with good precision.Searches for new particles were also performed at this energy,but they have already been superseded by the searches done at172GeV soon after.In the 172GeV run,the mass of the W gauge boson was determined directly,through the measurement of the invariant mass of its decay prod-ucts.Also a first look at the structure of the trilinear gauge-boson vertices 1To appear in the proceedings of “Beyond the Desert”,Castle Ringberg,Tegernsee,Germany,8-14June 1997.2E-mail address:miquel@ecm.ub.es 1was attempted.A short summary of W physics in thefirst year of LEP2 and its implications on limits for new physics can be found in section2.Results from the searches in the172GeV run for Higgs bosons(both from the Standard Model and from Supersymmetry models)and for super-symmetric particles are summarized in sections3and4,respectively.In the1995LEP run at a center-of-mass energy about130GeV,the ALEPH collaboration reported an excess of four-jet events with sum of jet-pair invariant masses close to105GeV[1].The analyses of ALEPH and the other LEP collaborations on this topic both in the161GeV run and in the172GeV run are discussed in section5.The reports of the H1and ZEUS collaborations at HERA hinting at possible new physics in electron-quark interactions[2]has prompted several analyses of electron-positron anihilation into quarks that are sensitive to some types of new physics that could explain the HERA events.Section6 summarizes the status after analysing the1996data.Finally,section7contains a summary of the talk.It should be noted that,unless specified otherwise,all results are to be understood as still preliminary.2.W physicsThe precise determination of the W mass serves as a stringent test of the Standard Model,since it can be predicted from the known values of the other parameters of the Standard Model.The only large uncertainty comes from the lack of knowledge of the Higgs boson mass,and therefore,mea-suring M W precisely enough,one can get information on the value of M H.The measurement of the W cross section close to the W-pair production threshold provides a clean and precise way to determine the W mass,since the phase-space factors appearing in the cross section expression depend strongly on the W mass.All four LEP experiments have already published theirfinal results on the WW cross section production at161GeV[3].The combined value for the WW cross section is[4]σW W(161.3GeV)=(3.69±0.45)pb.The error is dominated by statistics.From the total WW cross section at threshold,the W mass is obtained by using a Standard Model calculation that relates the WW cross section near threshold to its mass.The resulting W mass is:GeV,M W(161run)= 80.40+0.22−0.21±0.032where the last error reflects the current uncertainty on the LEP beam energy.Above the WW threshold,the most efficient way of determining the W mass is by measuring the invariant mass distribution of its decay products, either a charged lepton and a neutrino or a pair of jets.The detector resolution being far too poor to obtain a reasonably narrow invariant mass distribution,energy and momentum conservation have to be imposed in all channels to improve the resolution.The preliminary determinations of the four experiments agree very well with each other and the combined value reads[4]M W(172run)=(80.37±0.18exp±0.05theo±0.03beam)GeV.The dominant error includes statistical and purely experimental errors,the second one is the estimate of the uncertainty due to soft QCD effects and the third comes from the beam energy uncertainty.The two numbers can be combined[4]to give the preliminary W mass result from thefirst year of running of LEP2:M W=(80.38±0.14)GeV.This value is compared infig.1with the other measurements of M W,both direct at the Tevatron and indirect at LEP1and SLD.The agreement of all measurements is perfect.The current LEP2error is already quite good but still much larger than the40MeV uncertainty in the indirect measurement.To get a direct determination of M W with this sort of accuracy and to compare it against the indirect measurement, which assumes the Minimal Standard Model,is the next challenge for both LEP2and the Tevatron.The other important topic of WW physics at LEP2is the search for possible anomalous couplings between a pair of Ws and a Z or a pho-ton.However,these studies require the highest possible energy as well as substantial amount of integrated luminosity.The results available so far, which include only the semileptonic WW decays after the172GeV run, only improve marginally on the limits obtained previously at the Tevatron.3.Higgs searchThe main production process for the Standard Model Higgs at LEP2is its production associated with an on-shell Z.The cross section goes down to√a fraction of a picobarn once the Higgs mass reaches aboutW-Boson Mass [GeV]mW [GeV]State: m97parison of the direct W mass measurements at the Tevatron and LEP2and the indirect determination using LEP1and SLD data.run was not useful for Standard Model Higgs search,while the172GeV run started to extend the search region.The main decay channel for a Higgs boson with mass around70GeV is to a pair of b quarks.Therefore,according to the Z branching ratios,the final state ZH will consist70%of the times of four jets,two of them b s; 20%of the times of two b jets and missing energy;and10%of the times of two b jets and two charged leptons.The four-jet channel is both the most aboundant and the most difficult to separate from the background. Good b-tagging capabilities are mandatory and all the LEP experiments have invested recently in new and more powerful silicon vertex detectors. Typical efficiencies in the four-jet channel are around30%with very low background contamination.No experiment has found any evidence for an excess in any of the channels that have been searched.Typical95%4Actual CL Average CL LEP2 onlya)L31-CL = 5 %M H (GeV)1-C L b)95 % C.L. Line69.5 GeV L3M H (GeV)E x p e c t e d e v e n t s 10-310-210-1160657075800510156065707580Figure 2.a)Exclusion confidence level as a function of the Higgs mass for L3.b)Expected number of Standard Model Higgs events in L3as a function of the Higgs mass.The arrow points at the mass excluded at the 95%confidence limit.5confidence level limits on the mass of the Standard Model Higgs boson stand at around70–71GeV[5].Figure2shows the number of Higgs bosons expected by L3as a function of M H,and the limit taking into account the observed candidates(compatible with background expectations).In all Supersymmetry models at least two Higgs doublets appear,giv-ing rise tofive physical states:two charged Higgses,two neutral CP-even Higges(h,H)and a neutral CP-odd Higgs(A).In most SUSY theories there is an upper limit to the mass of the lightest CP-even neutral Higgs, h,which is around150GeV[6].Furthermore,in many models,its mass is below100GeV,suitable for its search at LEP2.The lightest CP-even Higgs can be produced in association with a Z, in a process very similar to its Standard Model counterpart,or in associa-tion with the CP-odd state,A.Both processes are complementary,in the sense that in the regions of the SUSY parameter space in which one cross section is small the other is large and viceversa,so that the overall rate of h production remains sizable in all regions with M h,M A<60−65GeV.Since all neutral Higgses decay predominantly to b jets,the channel hA involves identifying a four-jet event with four b s in thefinal state.As in the case of the Standard Model Higgs,no excess has been found[5]in any channel.Absolute95%confidence level mass limits on both h and A have been set at about62.5GeV for all values of tanβ≤1,where tanβis the ratio of the vacuum expectation value of the Higgs doublet that gives mass to up-type particles to that of the doublet that gives mass to down-type particles.Figure3shows the region in the plane M A−tanβexcluded by the DELPHI collaboration.4.Supersymmetry searchesSupersymmetry models not only predict more fundamental scalars.They predict for every particle in the Standard Model another particle with spin differing by±1/2,the supersymmetric partner.The partners of the charged Higgses and Ws are generally called charginos,while the partners of the neutral Higgses and neutral electroweak vector bosons are known as neutralinos.Charginos and neutralinos are expected to be the lightest SUSY particles.In particular,the lightest neutralino,χ,is supposed to be the lightest supersymmetric particle(LSP)in most models with gravity-mediated SUSY breaking.Searches have been performed for chargino pairs(χ+χ−),neutralino pairs(χχ′),whereχ′is the second lightest neutralino,scalar-lepton pairs (˜l+˜l−),scalar-top pairs(˜t1¯˜t1),etc.If R-parity is conserved,then the LSP, assumed to beχ,is stable and does not interact in the detector,so that6Figure3.Regions of the M A–tanβregion excluded by the DELPHI col-laboration under several assumptions.7the main experimental signature for the production of SUSY particles is the presence of large missing energy in the event.Several topologies involving jets and/or leptons and missing energy have been searched for by the four collaborations with negative results.There-fore,limits on the masses of the SUSY particles have been put.The cross sections used to derive the limits on the masses and the masses themselves depend on many of the parameteres of the SUSY models,making difficult the task of giving absolute limits.In most models,one can set a limit on the mass of the lightest chargino close to the kinematical limit,about85GeV.If,however,the scalar neu-trino mass is light(below100GeV),the limit degrades because the cross section for chargino production decreases,due to the diagram with a t-channel scalar neutrino exchange.The mass limit for the lightest neutralino is only about24GeV,assuming heavy scalar leptons.The result of the combined searches for charginos and neutralinos is customarily displayed as excluded areas in the M2−µplot,where M2andµare gauge-and Higgs-mass parameters appearing in the SUSY lagrangian.One such plot, showing the regions excluded by ALEPH,can be seen infig.4.Limits for scalar partners of leptons from53GeV(for˜τ)to75GeV (for˜e)have been put.Assuming that the lightest scalar top decays100% of the times to cχ,the limit on its mass is about65GeV for the value of the stop mixing angle which results in the smallest cross section.For some other values,the limit goes up to73GeV,as can be seen infig.5from OPAL[7].More details on all these limits can be found,for instance,in ref.[9].In models in which supersymmetry is broken via gauge interactions, the gravitino(SUSY partner of the graviton)is the LSP.Then,ifχis the next-to-lightest SUSY particle,the production of a pairχχcan result in a final stateγγ˜G˜G,that is,two acoplanar photons plus missing energy,since the gravitinos stay undetected.Searches for these kind of events have been unsuccesful and limits on mχaround72GeV have been set within some particular models[10].5.Four-jet anomalyIn the autumn1995run at energies close to130GeV,the ALEPH collabo-ration reported an excess of four-jet events in which the sum of the two jet-pair invariant masses that differed the least was peaked at about105GeV, as shown infig.6from ref.[1].The excess was not confirmed by the other three LEP collaborations.Four-jet events have been studied by all LEP collaborations at both runs at161GeV and172GeV.While ALEPH seems to confirm their initialfinding,although with lower significance,DELPHI,8µ (GeV)Figure 4.Regions of the M 2–µregion excluded by the ALEPH collabora-tion for tan β=√0204060804050607080m ( t ∼1 ) [ GeV ]m ( χ∼10) [ G e V ]OPAL t ∼ → c χ∼10(b)θ t ∼ = 0.0θ t ∼ = 0.98excluded Figure 5.Regions in the m ˜t 1−m χplane excluded by OPAL [7]for severalvalues of the stop mixing angle,assuming the decay goes as ˜t1→cχ100%of the times.The cross-hatched area had already been excluded at LEP1,while the single-hatched area has been excluded by D0[8].10Figure6.Distribution of the sum of the invariant masses of the two jet pairs with smallest invariant mass difference in four-jet events,from ALEPH at 130GeV[1].11√s=133-172 GeV05101520253035ΣM for minimum δM024681012ΣM for minimum δM Figure 7.Distribution of the sum of the invariant masses of the two jet pairs with smallest invariant mass difference in four-jet events at 130,161and 172GeV put together,from DELPHI,L3and OPAL (top plot)and from ALEPH (bottom plot).12L3and OPAL continue to see no deviation from the Standard Model ex-pectations.A LEP-wide working group on the subject has concluded[11]that the four experiments are able to select and reconstruct four-jet events with similar efficiencies and mass resolutions.Figure7shows the combined results at all energies from130to172GeV for DLO(that is,DELPHI,L3and OPAL combined)and for ALEPH.The discrepancy is clear.The study concludes that the probability for the ALEPH observation to be due to a statisticalfluctuation is about7×10−4,while the probability for both the ALEPH and the DLO observations to be compatible with asignal at105GeV is also about7×10−4!It is clear that,so far,the origin of the effect is not understood.6.Constraints on possible explanations of HERA eventsIf the excess of high Q2events seen in H1and ZEUS at HERA[2]is dueto new physics affecting the coupling between quarks and electrons,there could be also effects in the process e+e−→q¯q,very well studied at LEP. The OPAL collaboration has investigated two scenarios[12],either with thepresence of four-fermion contact iteractions between e−e−q−q,or with the exchange of a scalar particle in the t-channel of the reaction e+e−→q¯q.By measuring the cross section for hadron production and,separately, the ratio of b¯bfinal states to all hadronicfinal states,both at161and at172GeV,OPAL has put limits on the mass scale appearing in the contact-term lagrangian between1.0and2.5TeV,depending on the type of interaction and on whether the interaction affects one up-type quark or one down-type quark.It should be noted that,in spite of the huge statistics accumulated at LEP1,this kind of search is more sensitive at LEP2because at the Z peak the interference between the new amplitude(purely real)and the dominant Z amplitude(almost purely imaginary)almost vanishes and one is left with the purely new effect squared.If a t-channel exchange of a scalar leptoquark or a scalar quark violating R-parity is assumed,some constraints on possible models explaining the HERA excess events can be obtained.The constraints will become truly severe once the1997data is analysed.7.SummaryAfter analysing the data from thefirst year of LEP2,no deviation from the Standard Model predictions has been found:13•The direct measurement of the W mass agrees with the previous in-direct determinations using LEP1/SLD data and assuming the Stan-dard Model.•Limits on Higgs and Supersymmetry particles have been greatly ex-tended.For example,the Standard Model Higgs has to be heavier than71GeV,the SUSY Higgses h and A heavier than62.5GeV, and the lightest chargino heavier than85GeV in most of the SUSY parameter space.•The four jet anomaly reported by ALEPH in1995remains a mistery, having been confirmed by ALEPH in1996but not seen by any of the other LEP experiments.•Analysing the reaction e+e−→q¯q the LEP experiments can start to get interesting constraints on models trying to explain the high Q2 HERA eventsAcknowledgmentsIt has been a great pleasure to attend this conference in such a nice set-ting and with such an attendance.I am most thankful to Prof.Klapdor-Kleingrothaus for his invitation to give this talk and to him and all his team for making the whole week so enjoyable.I would also like to thank Dr.Michael Schmitt for his help in the preparation of this talk.References[1]Buskulic D et al(ALEPH Collaboration)1996Z.Phys.C71179[2]AdloffC et al(H1Collaboration)1997Z.Phys.C74191Breitweg J et al(ZEUS Collaboration)1997Z.Phys.C74207[3]Barate R et al(ALEPH Collaboration)1997Phys.Lett.B401347Abreu P et al(DELPHI Collaboration)1997Phys.Lett.B397158Acciarri M et al(L3Collaboration)1997Phys.Lett.B398223AckerstaffK et al(OPAL Collaboration)1996Phys.Lett.B389416 [4]Abbaneo D et al(LEP Electroweak Working Group)A Combination ofPreliminary Electroweak Measurements and Constraints on the StandardModel,LEPEWWG/97-01[5]Barate R et al(ALEPH Collaboration)1997CERN-PPE/97-070Acciarri M et al(L3Collaboration)1997CERN-PPE/97-081[6]Kane G L,Kolda C and Wells J D1993Phys.Rev.Lett.702686Espinosa J R and Quiros M1993Phys.Lett.B3025114[7]AckerstaffK et al(OPAL Collaboration)1997CERN-PPE/97-046[8]Abachi F et al(D0Collaboration)1996Phys.Rev.Lett.762222[9]Cerutti F(1997)to appear in Proceedings of the SUSY97conference,Philadelphia[10]Lopez J and Nanopoulos D(1997)Phys.Rev.D554450[11]Bizouard M A et al(LEP Working Group on Four Jets)Report of the LEPWorking Group on four-jet production in e+e−collisions at centre-of-mass energies of130–172GeV,ALEPH97-056PHYSIC97-050,DEL-PHI97-57PHYS707,L3note2090,OPAL Technical Note TN486 [12]Komamiya S LEPC presentation,CERN,February25th1997.15。

New physics in Bs decays to Jpsi and phi

New physics in Bs decays to Jpsi and phi

New Physics in B s decays to the vector mesons J/ψ and φW.N.Cottingham Physics Department University of Bristol Tyndall Avenue Bristol BS81TLAbstract This paper is concerned with the physics of ssB and Bmeson decays to J/ψ and φ.These decays have been observed at the Tevatron [7] and, in particular, should be copiously observed at the LHCb detector. This paper gives a concise presentation of the basic physics analysis and a general formalism for analyzing the signals of CP violation.The primary object of this paper is to pursue the work of I.Dunietz et al [1] on signals of new physics in B s decays but gives an extended discussion of J/ψ , φ production with the subsequent electromagnetic and strong decays J/ψ -> l -- l + and φ -> K -- K + . The work of [1] emphasizes the very real possibility of enhanced CP violation in s s B B mixing. In particular heavy particles, outside of the standard model, could contribute to the box diagrams, and in particular to M 12 responsible for mixing. With new CP violating phases signals of such new contributions could be observed with the copious event rates in the LHCb detector. We extend the work of A.Dighe et al [2,3] to give a fuller discussion of the signals of CP violation which could reveal any new physics .We also emphasize the importance of s s B B , production rate asymmetry which gives access to data otherwise only available through tagging.The two mass eigenstates of the s s B B , system are s s L B q B p B += is the lighter eigenstate s s H B q B p B −= is the heavierWe adopt the convention of Dunietz et al [1], s s B CP B −= so that with no CP volation in mixing p = - qThe decay rate of a meson tagged at time t = 0 as a to a final state f is denoted by (See also [1]) s B[])))(Re((24),(22ix f f f f y ff y fftf s e A z A A z A e A z A e A z Ae N t B dt d ∗+−Γ−−++−++=Γand for a meson tagged as a s B at time t = 0[])))(Re((24),(222ix f f f f y ff y fftfs e A z A A z A e A z A e A z Aze N t B dt d ∗+−Γ−−+−−++=Γff A and A are the decay amplitudes for f B and f B s s →→ at time t = 0 , is a normalization factor, f N p q z = , x and y are timedependent quantities t m x s ∆= and 2t y s ∆Γ=, H L s Γ−Γ=∆Γ So far experiment is consistent with standard modelexpectations The D0 collaboration measure ∆m s in the interval 17 to 21 ps -1 [5]. ∆Γs is expected to be in the interval 0.06 to 0.14 ps -1 [6] and Γs = 0.684 ± 0.039 ps -1 [4]. At the LHCb for example there is no reason to expect that s B and s B mesons will be produced in equal numbers, with a significant production rate asymmetry much information can be gleaned without tagging . With a production rate asymmetry Asy, the untagged rate is the sum of the tagged rates with weighting ½ (1 + Asy) and ½ (1 – Asy) , all three time dependent terms survive.The final state f is a charged lepton pair and a K -- K + pair.We take the J/ψ direction in the Bs rest frame to define the z axis, and the polar angles l l and φθ by the negative lepton direction, having moved to the J/ψ rest frame,)cos ,sin sin ,cos sin (ˆˆl l l l l l l p pθφθφθ=−=+−Similarly in the φ rest frame we take the K -- direction to be)cos ,sin sin ,cos sin (ˆˆK K K K K K K p pθφθφθ=−=+−To identify the vector mesons by constructing their masses, these angles, up to an overall azimuthal angle say K φ, will have to be determined either explicitly or implicitly for every event. We use these angular variables because they explicitly include theimportant azimuthal angle K l φφ−=∆, to translate to the angles ψϕθand , of Dighe et al [1,2,3]∆=∆−===sin sin cos ,cos sin sin sin ,cos cos sin ,l l l K θθθϕθθϕθθψNeglecting terms of order 2/⎟⎟⎠⎞⎜⎜⎝⎛ΨJ lmm the helicities of the lepton pairare opposite, the net lepton spin projection m along is either m = +1 or m = -1, we here assume that no lepton helicity is measured and sum these two final spin states.−l pˆ For m = +1 the decay amplitude for a Bs meson can be taken to be()()()∆−∆+−++−+−=+=i K l K l i K l f e P i S s c c s L e P i S s c m A )(12)(11S and L are complex parameters that come from even parity (S and D wave) J/ψ φ states, P is a complex parameter from the odd parity P wave state. are shorthand notations for K K l l s and c s c K l K K l l and φφθθθθ−=∆,sin cos ,sin ,cos . The parameters are complex due to phases of the basic production amplitudes but also from the J/ψ and φ propagators and from final state interactions. S – iP , L and S + iP correspond to positive, zero and negative helicity J/ψ φ intermediate states. The CDF collaboration [7] have found that L accounts for 50% or more of the total. For m = -1 we have ),,1()1(K K l l f f c c c c m A m A −→−→+=−=−=Note are always positive (0 < θ < π). For the K e s and s s B decay amplitudes),,,1()1(L L P P S S m A m A f f →−→→+=−=+= ),,,1()1(L L P P S S m A m A f f →−→→−=−=−=In these last three equations quantities that remain unchanged are not exhibited. With the neglect of direct CP violation L L and P P S S ===,.We define L L L and P P P S S S δδδ+=+=+=000L L L z and P P P z S S S z δδδ−=−−=−−=−000CP violation is expected to be small and here we include in the decay rates only terms up to first order in the small quantities L and P S δδδ,,. The rates are combinations of six angular functions)cos()2sin()2sin()sin()2sin()2sin()2sin()(sin )(sin )(cos )(sin ))(cos )(sin 1)((sin ))(sin )(sin 1)((sin 6522422322222221∆=∆=∆==∆−=∆−=K l K l l K K l l K l K F F F F F F θθθθθθθθθθθθTranslating these functions to the angles of Dighe et al, they are)2sin()(sin )2sin()cos()2sin()2sin()2sin()(sin )(sin )(cos )(sin 1()(cos ))(sin )(sin 1)((sin )(sin )(sin 2652422232222221ϕθψϕθψθϕψϕθψϕθψθψ−==−=−=−==F F F F F FWe find[]∑∗∗−−=−mff F L P al F S P al F P A z A 50401202)(Re )(Re 2216δδ∑⎥⎥⎦⎤⎢⎢⎣⎡−−−+=+∗∗∗mf f F P L al F P S al F S L al F L F S A z A 50406003202202)(Re )(Re 2)(Re 2216δδ ()()∑=−+∗m f f f f A z A A z A 2 ⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡+−+++−−∗∗∗∗∗∗∗6003010********)(444216F S L L S F L L F P P F S S F P L F P S δδδδδ Particularly simple and revealing expressions result if theangles K l and θθ and the irrelevant azimuthal rotation about the J/ψ direction are summed over (see also [2]), then⎥⎦⎤⎢⎣⎡∆∆+∆+∆=∆Γ∆Γ+∆Γ−Γ−),()()(),(22/2t m A e A e A e N d dt t B d Mt H t Ltf s ⎥⎦⎤⎢⎣⎡∆∆−∆+∆=∆Γ∆Γ+∆Γ−Γ−),()()(),(222/2t m A e A e A z e N d dt t B d Mt H t L t f s with no tagging but with some production rate asymmetry Asy⎥⎥⎦⎤⎢⎢⎣⎡∆∆−++⎥⎦⎤⎢⎣⎡∆+∆−+=∆Γ∆Γ+∆Γ−Γ−),())1(()()()1(),(22/2t m A Asy e A e A Asy eN d dt t B d M t H t Ltfuntagged εεεε ()∆−−∆+=∆2sin )cos(2))2cos(2()(0020S P H P S P A δδδδ()∆−−+∆−=∆2sin )cos(2))2cos(2()(00220P S L S P L S A δδδδ()⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡∆+∆−−+∆−∆−−+∆−−∆∆−−−=∆∆))2cos(2()cos()2cos 2()cos()cos()2sin()cos(2),(0000000000t m P P t m S S t m L L t m P S t m A P P S S L L S P M δδδδδδδδδδδδδδSP and δδδ0are the phases of S and P δ0etc is a normalizationfactor and /fN 211z−=ε is very small.It is very important to note that in the individual the CP violating terms have their own characteristic angular dependence which can be used to isolate them. Focusing first on the dominant CP conserving terms, with no tagging but resolvingfrom the different decay rates M H L A and A A H L A and A 202020,L and P S can be determined through the angular dependence. With accurate timing and angular resolution in ∆, 00P S Asy can also be measured and the production rate asymmetry inferred .Returning to the work of I.Dunietz et. al. [1] and to physics beyond the standard model the most likely signal will be in the CP violating terms. In the standard model one can expect only very small direct CP violation The work of [1] and [8] suggests that the most likely signal of new physics will be in the mixing parameter z ( = q/p). With no CP violation in mixing z = -1.The standard model has z very close to -1 and the parameter p = (1 + z)/2 to be almost pure imaginary and of magnitude 2 10 -5 , plausibly in extended models p could be much enhanced. With no direct CP violation δS/S 0 = δP/P 0 = δL/L 0 = p The work of [1] suggests that p could have a small real part, in their notation and to first order in small quantities)21(21a i p M +=φThis results in the expression{}{}{}(){}(){}{}⎥⎥⎥⎥⎥⎥⎥⎥⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎢⎢⎢⎢⎢⎢⎢⎢⎣⎡−++−+−−+−++−−+−+++++++−−=Γ−−−−−Γ−)cos()sin()cos()cos(21)sin()cos()cos(21)sin(2)sin(2)sin(2)sin(24),(12006222005111004203202201δδζφζδζδφδζδζδφδζφζφζφx e S L F e e x P L F e e x P S F x e L F x e S F x e P F e N t B dt d y y y y y y y y tf s422a M +=φφ ⎟⎠⎞⎜⎝⎛=M a φζ2arctan 21πδδδ−−=S P 22πδδδ−−=L P This formula is consistent with that of Dighe et al with S 0 = A ׀׀ , P 0 = -i A ┴ and L 0 = 2A 0For a meson tagged as a s B at time t = 0 the time dependent terms involving )(t m x s ∆= are of opposite sign.ACKNOWLEDGEMENTSI thank my colleagues Dr J. Rademacker and Prof.N.Brook for suggesting this work, and Dr A.F.Osorio for helpful correspondenceReferences1 I.Dunietz, R.Fleischer, and U.Nierste. Phys. Rev. D 63 (2001) 1140152 A.Dighe, I.Dunietz, H.Lipkin, J.Rosner, Phys. Letts, B369 (1996) 1443 A.Dighe I Dunietz R.Fleischer. Eur. Phys. J. C6 (1999) 6474 S.Eidelman et al Phys. Letts. B592 (2004) 15 R.Van Kooten, FPCP Conference Vancouver April 2006 6 M.Beneke, G.Buchalla, C.Greub, A.Lentz, U.Nierste, Physics Letters B 459(1999) 6317 CDF collaboration Phys Rev Letts 75 (1995) 17 8 U.Nierste Fermi Lab Flavor Seminar March 2006。

人教版高考英语一轮总复习课后习题 选择性必修第2册 UNIT 1

人教版高考英语一轮总复习课后习题 选择性必修第2册 UNIT 1

UNIT 1 SCIENCE AND SCIENTISTSⅠ.阅读理解AEugene Newman Parker,a leading figure in heliospheric(日球层的) physics for the past half century,passed away peacefully at his home in Chicago on Mar.15.He was 94.Hailed(誉为) as a visionary in the field of heliophysics,Parker revolutionized our understanding of the sun and its effects on Earth and other bodies within the solar system.NASA even stated that the field of heliophysics exists in large part because of Dr.Eugene Parker.In ,Parker became the first living scientist to witness the launch of a spacecraft that was named in his honor.Parker is best known for his groundbreaking theory on the eenon called “solar wind”,a continuous stream of charge d particles that flow off the sun.It can become violent,causing space weather that impacts Earth.When Parker’s research was published in 1958,his theory was initially met with skepticism(怀疑) and ridicule by the scientific community.The general view at the time was that the spacebetween planets was an absolute vacuum(真空),and was thus completely empty of any matter.But,there were no errors in his study or his calculations,and the theory was later proven to be correct in 1962,when a NASA spacecraft mission to Venus revealed the constant presence of a supersonic wind—exactly as Parker had predicted.That experience likely led to the advice Parker often gave young researchers:“If you do something new or innovative,expect trouble.But think critically about it because if you’re wrong,you want to be the first one to know that.” Parker never co-authored a paper with his students,thus urging them to be independent.Parker was humble,straightforward,and wise.His son Eric said,“My sister Joyce and I didn’t get a real feel for what a ‘big dog’our dad was in the field.” They got an even better sense when a month after Parker’s death,they traveled to Lund,Sweden,to accept on his behalf the Crafoord Prize in Astronomy.1.What can we learn from the second paragraph?A.A spacecraft was named in memory of Parker.B.The sun has fewer effects on Earth than expected.C.Parker deserved credit for his great contributions.D.NASA provided new insights into the lunar effect.2.Why did people view Parker’s theory of “solar wind” skepti cally at first?A.It went against the popular opinion at that time.B.Some mistakes were found in his calculations.C.The presence of a supersonic wind was proven by NASA.D.Matter was believed to exist in the space between planets.3.What did Parker suggest young researchers do?A.Seek close cooperation.B.Avoid high expectations.C.Learn by trial and error.pete against others.4.What words can be used to describe Parker according to the passage?A.Straightforward and generous.B.Responsible and accessible.C.Intelligent yet conservative.D.Distinguished yet modest.BTechnology is starting to give us superpowers once reserved only for comic book heroes like Spider-Man and Superman.We now live in an age of human enhancement and related technology has captured the attention of the media and investors.Some of these new technologies achieve their effects by means of electronic devices that connect our brains to external sources of knowledge,sensory data or physical power.We may not get chips implanted in our brains any time soon,but think about Google Glass—who needs an inserted chip when you can wear a computer on your head?Wearable technology doesn’t only come in the form of a pair of glasses.A Japanese laboratory is working on a more practical prototype(雏形) of a muscle suit than Iron Man’s shiny armor(盔甲).The muscle suit,called an exoskeleton,enables the sick and elderly to move around more easily,NewScientist magazinereported.Coveting(觊觎) the powers of Spider-Man,the US military is working on a “Spider-Man suit” that not only lets wearers climb vertical walls,but also allows them to sense approaching objects without looking at or hearing them,according to an American military technology website.But perhaps you favor more subtle powers like mind control or mind reading.This may one day come true as well.The most amazing human enhancement technologies that have come into reality are devices that interact directly with the human brain.Q Sensor,created by scientists at MIT,is a wireless sensor that measures electricity conducted through the skin.It can detect whether people are bored,stressed or excited,and therefore has wide applications in research and therapy,the BBC reported.Scientists envision neural implants that could allow humans to manipulate real-world objects with their mind—a power not unlike mind control.Slate magazine reported this might already be happening.5.What can be learned from the first two paragraphs?A.New technologies have brought us into a new era.B.Superpowers of comic book heroes have been widely applied nowadays.C.Human enhancement refers to the superpowers of the comic book heroes.D.Spider-Man and Superman have captured the attention of the media and investors.6.What can we know about Google Glass?A.It is implanted in our brains.B.It is a technology with inserted chips.C.It is a device which makes us superheroes.D.It is a technology that enhances human power.7.Which of the following items does NOT involve wearable technology?A.Google Glass.B.The muscle suit.C.Iron Man’s armor.D.The Spider-Man suit.8.What is the best title of the passage?A.Ean enhancementB.Go beyond Iron Man’s shiny armorC.Meet superheroes in real lifeD.Embrace the unknown worldⅡ.完形填空Wearing a caveman mask,Dr.Marzluff walks across the camp at the university.Crows circle and scream.They dive at him and then suddenly fly away.Beneath the mask,he smiles.Days before,he and his students had 1 cavemen masks,caught crows and 2 plastic bands on to their legs.Then they released the 3 birds.“We always knew crows 4 us,but could we show it?” says Dr.Marzluff,a professor known affectionately as the Crowman.When the researchers walked around campus without masks,the crows they had caught and banded didn’t 5 to them.But when the 6 humans walked by while wearing the masks,the crows scolded loudly and dived at their “7 ”.The birds had remembered their 8 !“Crows are constantly 9 us,” Dr.Marzluff says.“They look,they think,and they eyeball you, 10 the situation.”At first,only the banded birds reacted 11 to the people in masks.But in later tests,an increasing number of crows began scolding them,even when the banded birds were not around.The birds had 12 from one another.Dr.Marzluff and his team followed banded crows for a year and 13 that adults even pass this information to their 14 .Dr.Marzluff’s e to study how crows’15 work.1.A.picked out B.put onC.searched forD.taken off2.A.dropped B.steppedC.pressedD.tied3.A.unhappy B.beautifulC.blackD.rare4.A.hate B.attackC.recognizeD.contact5.A.wave B.reactC.replyD.turn6.A.friendly B.unkindC.differentD.same7.A.enemies B.professorsC.ownersD.followers8.A.clothes B.facesansD.figures9.A.eiringC.watchingD.tolerating10.A.estimating B.changingC.restoringD.worsening11.A.rigidly B.automaticallyC.abnormallyD.threateningly12.A.resulted B.heardC.learnedD.benefited13.A.promised B.identifiedC.deniedD.clarified14.A.young B.neighborC.partnersD.opponents15.A.wings B.nosesC.legsD.brainsⅢ.读后续写阅读下面材料,根据其内容和所给段落开头语续写两段,使之构成一篇完整的短文。

高二英语科学发现单选题50题

高二英语科学发现单选题50题

高二英语科学发现单选题50题1. The ______ of the light bulb by Thomas Edison had a great impact on the world.A. inventionB. discoveryC. explorationD. creation答案：A。

解析：“invention”强调创造出以前不存在的东西，灯泡是爱迪生创造发明出来的，所以选A。

“discovery”侧重于发现原本就存在但不为人知的事物；“exploration”主要指探索、探究；“creation”更侧重于创造抽象的事物或艺术作品等，在表示发明具体物品时不如“invention”合适。

2. Alexander Fleming is famous for his ______ of penicillin.A. inventionB. discoveryC. findD. creation答案：B。

解析：“discovery”指发现原本存在但未被发现的事物，青霉素原本就存在，弗莱明是发现了它，所以选B。

“invention”强调发明新的东西；“find”作名词时没有这种科学发现的含义；“creation”侧重于创造抽象或艺术等方面的东西。

3. Which of the following is the correct English term for “万有引力”that was discovered by Isaac Newton?A. Universal GravityB. General GravityC. Total GravityD. Whole Gravity答案：A。

解析：“Universal Gravity”是“万有引力”的正确英文表达。

“General”通常表示一般的、总体的；“Total”表示总数的、总计的；“Whole”表示整个的，都不能准确表达“万有引力”这个科学概念。