a r X i v :h e p -p h /0104217v 1 22 A p r 2001
TIFR/TH/01-02hep-ph/0104217
Characteristic Wino Signals in a Linear Collider from Anomaly
Mediated Supersymmetry Breaking
Dilip Kumar Ghosh a,1,Anirban Kundu b,2,Probir Roy c,3and Sourov Roy c,4
a
Department of Physics,National Taiwan University
Taipei,TAIWAN
b
Department of Physics,Jadavpur University,Kolkata -700032,INDIA
c
Department of Theoretical Physics,Tata Institute of Fundamental Research
Homi Bhabha Road,Mumbai -400005,INDIA
Abstract
Though the minimal model of anomaly mediated supersymmetry breaking has been signif-icantly constrained by recent experimental and theoretical work,there are still allowed regions of the parameter space for moderate to large values of tan β.We show that these regions will
be comprehensively probed in a
√
s =1TeV corresponding to the proposed TESLA linear collider in two natural
categories of mass ordering in the sparticle spectra.The signals analysed comprise multiple combinations of fast charged leptons (any of which can act as the trigger)plus displaced ver-tices X D (any of which can be identi?ed by a heavy ionizing track terminating in the detector)and/or associated soft pions with characteristic momentum distributions.
1Introduction
The Minimal Supersymmetric Standard Model(MSSM[1]),with softly broken N=1supersymmetry, is the prime candidate today for physics beyond the Standard Model(SM).Suppose the soft supersymmetry breaking terms explicitly appearing in the MSSM Lagrangian are regarded as low energy remnants of a spontaneous or dynamical breaking of supersymmetry at a high scale.We then know that the latter cannot take place in the observable sector of MSSM?elds;it must occur in a hidden or secluded sector which is generally a singlet under SM gauge transformations.Though the precise mechanism of how supersymmetry breaking is transmitted to the observable sector of MSSM super?elds is unknown,signals of supersymmetry in collider experiments sometimes depend sensitively on it.There are several di?erent ideas of transmission,such as gravitational mediation at the tree level[2]and gauge mediation[3],each with its distinct signatures.A very interesting recent idea,that is di?erent from the above two,is that of Anomaly Mediated Supersymmetry Breaking(AMSB)[4,5]which is explained below.This scenario has led to a whole class of models and their phenomenological implications have been discussed[4-23],but let us con?ne ourselves here to the minimal version[4].The latter has characteristically distinct and unique laboratory signatures.These have been explored in some detail for hadronic collider processes[8-13].But there are also quite striking signals that such models predict for processes to be studied in a high energy e+e?(orμ+μ?)linear collider[14].This paper aims to provide a?rst detailed study of such signals in this type of a machine.
In ordinary gravity-mediated supersymmetry breaking tree level exchanges with gravitational couplings between the hidden and the observable sectors transmit supersymmetry breaking from one to the other.IfΛss is the scale of spontaneous or dynamical breaking of supersymmetry in the hidden sector,explicit supersymmetry violating mass parameters of order M s≡Λ2ss M?1pl,
M pl being the reduced Planck mass～2×1018GeV,get generated in the MSSM Lagrangian. However,in general,there are uncontrolled?avour changing neutral current(FCNC)amplitudes in this scenario.Though gravity is?avour blind,the supergravity invariance of the Lagrangian still admits direct interaction terms between the hidden and the observable sectors,such as
L eff? d4θh
Attempts to solve the above mentioned ?avour problem have generally required special family symmetries [25]in addition to supergravity.In the alternative scenario [3],namely gauge mediated supersymmetry breaking,FCNC amplitudes are naturally absent.However,models of that category have other di?culties like the CP problem and the μvs μB (μand B being the higgsino mass and the Higgs sector supersymmetry violating parameters respectively)problem which are less severe in gravity-mediated scenarios.It is in this context that the recently proposed AMSB scenario has right away become interesting.Anomaly mediation is in fact a special case of gravity mediation where there are no direct tree level couplings between the super?elds of the hidden and the observable sectors that convey supersymmetry breaking.This is realized,for instance,when the hidden and the observable sector super?elds are localized on two parallel but distinct 3-branes located in a higher dimensional bulk as schematically depicted in Fig.1.
3
-b r
a n e V i
s i b l e s e
c t o r BULK
(Super-Weyl anomaly)
H
i d d e
n
s e c t o r 3-b r a n e Figure 1:Supersymmetry breaking across the extra dimension(s).
Suppose that the two branes are separated by the bulk distance ～r c where r c is the compacti-?cation radius.Then any tree level exchange with bulk ?elds of mass m (>r ?1c
)will be suppressed by the factor e ?mr c .Supergravity ?elds propagate in the bulk,but the supergravity-mediated tree level couplings can now be eliminated by a rescaling transformation.The problem can be considered in the background of a conformal compensator super?eld Φwhose VEV is given [4]by Φ =1+m 3/2θθ,m 3/2being the gravitino mass.The rescaling transformation is then given by
Q Φ→Q .However,this rescaling symmetry is anomalous at the quantum level and the communi-cation of supersymmetry breaking from the hidden to the observable sector takes place through the loop-generated superconformal anomaly.The latter is topological in origin and naturally conserves
?avour so that no new FCNC amplitudes are introduced from supersymmetry breaking terms.Thus other advantages of gravity mediated supersymmetry breaking are retained in the AMSB scenario while the?avour problem is solved.
Let us assume that all explicit soft supersymmetry breaking parameters of the MSSM originate from AMSB.Then the masses of the gauginos and of the scalars get generated at the same order in the corresponding gauge coupling strengths.Therefore these masses are not expected to be very di?erent.The expressions for the said quantities,in fact,become renormalization group invariant with sleptons becoming tachyonic.The latter fact is the most severe problem in the AMSB scenario and there are several proposals in the literature to solve it.We shall focus on the minimal[4]model of AMSB where the problem of tachyonic sleptons is tackled by adding a universal constant term m20to the expressions for squared scalar masses,i.e.,m20contributes equally to the squared masses of all scalars present in the theory.One can now solve the tachyonic slepton problem through a suitably chosen m20making all squared slepton masses positive,the scale invariance of the expressions for scalar masses being lost.The evolution of scalar masses governed by the corresponding renormalization group equations(RGE),starting from a very high energy scale,must therefore be taken into account.However,except for the addition of an extra parameter,this is quite a feasible procedure.Recently,a mechanism to generate the minimal AMSB spectrum(including the universal additive constant m20in all squared scalar masses)has been proposed[23].In this scheme only the SM matter super?elds are con?ned to the3-brane of the observable sector while the gauge super?elds live in the bulk along with gravity.The presence of gauge and gaugino?elds in the bulk results in the additional universal supersymmetry breaking contribution to all scalar masses squared.This contribution is naturally of the same size as its anomaly-induced counterparts.
One can say,on the basis of this last discussion,that the minimal AMSB model has now been soundly formulated and is worthy of serious consideration.Indeed,its parameter space has been severely constrained[26-29]by recent measurements of the g?2of the muon[30]and of the branching fraction for the decay B→X sγ,but some regions of the parameter space still survive.This model is characterized by several distinct features with important phenomenological consequences:a rather massive gravitino(～a few TeV)and nearly mass-degenerate left and right selectrons and smuons while the staus split into two distinct mass eigenstates with the?τ1being the lightest charged slepton.Most importantly,the model has gaugino masses proportional to the β-functions of the gauge couplings.The latter leads to the existence of a neutral near-Wino as the lightest supersymmetric particle(LSP) χ01and closely mass-degenerate with it a pair of charged near-Winos as the lighter charginos χ±1.A tiny mass di?erence?M(<1GeV)arises between them from loop corrections and a weak gaugino-higgsino mixing at the tree level.Because of the small magnitude of?M, χ±1,if produced in a detector,will be long-lived.Such a chargino then is likely to leave[31]a displaced vertex X D and/or a characteristic soft pion from the decay χ±1→ χ01+π±.
The pair production of MSSM sparticles and their decays which are characteristic of AMSB
scenarios,have been considered in various theoretical studies conducted with respect to experiments in a hadronic collider[8-13].But the same can be carried out for electron and muon colliders too
√
[14].Let us speci?cally take an e+e?linear collider at a CM energy
s=500GeV linear collider,the proposed JLC and NLC machines. It is interesting to note that the region still allowed by the(g?2)μand the B→X sγconstraints is almost the one allowed from more theoretically motivated stability conditions.This is why we √
have chosen a
1See,for example,the second paper in[15].
2Similar considerations apply to a futureμ+μ?collider with the di?erence that the pair production of smuons will be more copious than that of selectrons.
extreme degeneracy of the right and left selectrons(smuons)is lost here with the right becoming heavier.This feature can change the patterns of the cascade decays of various sparticles leading to observable consequences di?erent from those of the minimal model.We shall discuss these complications separately.
The paper is organized as follows.In section2we describe and discuss the mass spectra of the minimal AMSB model and distinguish between the two cases A and B.In section3,we enumerate processes of the pair production of di?erent sleptons and neutralinos,as mentioned earlier;we also consider the relevant cascade decay chains that lead to our desired signals.The numerical results of these computations are presented in section4which also contains discussions of the results.The ?nal section5provides a brief summary of our conclusions.
2Spectra and Couplings of the Minimal AMSB Model
Scalar masses in the minimal AMSB model are determined via the RGE equations of the MSSM with appropriate boundary conditions at the gauge coupling uni?cation scale M G～(1.5?2.0)×
1016GeV.In the present analysis,the evolution of gauge and Yukawa couplings as well as that of scalar mass parameters are computed using two-loop RGE equations[34].We have also incorpo-rated the uni?cation of gauge couplings at that scale withα3(M Z)≈0.118.The magnitude of the higgsino mass parameterμgets?xed from the requirement of a radiative electroweak symmetry breaking.It is computed at the complete one-loop level of the e?ective potential[35],the optimal choice for the renormalization scale being Q=
m3/2.(2)
16π2
where b1=33/5,b2=1,b3=?3.To leading order,M1,2,3are independent of m0and increase linearly with m3/2.Furthermore,at one-loop level the squared masses for the Higgs and third generation scalars are
m2i=C i m2
3/2
50
g41?3
25g41+8g43+2h t?βh
t
,
CˉD=?
22
50
g41?3
25g41+2hτ?βh
τ
,
C H
u =?
99
2
g42+3h t?βh
t
,
C H
d =?
99
2
g42+3h b?βh
b
+hτ?βh
τ
.
In Eqs.(4),Q and L refer to the respective squark and slepton SU(2)doublet super?elds,whileˉU,ˉD andˉE stand for the singlet up-squark,down-squark and charged slepton super?elds respectively and H u(H d)describes the up-type(down-type)Higgs super?eld.Moreover,the?β’s are given by
?β=(16π2)?1β,(5) whereβis the usual beta-function.Thus
?β
h t=h t ?133g23+6h2t+h2b ,
?β
h b=h b ?73g23+h2t+6h2b+h2τ ,
?β
hτ=hτ ?9
h t m3/2
h b
m3/2
hτ
m3/2
(Note that eq.(7),as deduced in[9],is true only for low and moderate values of tanβ.For large values of tanβwhere bottom andτYukawa couplings are nonnegligible,the ratio|M1|/|M2|slightly
increases[13].)As a result of eq.(7),the lighter chargino χ±1and the lightest neutralino χ01become almost degenerate.The small di?erence in the masses,with the lightest neutralino being the lightest supersymmetric particle(LSP),comes from the tree-level gaugino-higgsino mixing as well as from the one-loop corrected chargino and the neutralino mass matrix.The small mass-splitting?M can be approximately written as
?M=M4W tan2θW
μ
,
M2W
πsin2θW f
M2W M22 ,(8)
with
f(x)≡?x
8
ln(x)+
1
2 √√
AMSB scenario gives the ratio|μ/M2|to be approximately between3and6.For very large M2(i.e. for very largeμ)the mass di?erence?M reaches an asymptotic value of≈165MeV.Fig.2shows the typical variation of?M as a function of m3/2for a choice ofμ>0and m0=450GeV.The two choices of tanβare shown in the?gure.The curve is cut o?on the left by the lower bound3on m3/2implied by the experimental constraint[37]on the χ±1mass(m χ±1>86GeV)for the nearly degenerate χ±1- χ01case.On the right,it gets terminated because otherwise the stau becomes the LSP with a further increase4in m3/2for this particular value of m0.This is also the reason why we have not been able to show the limiting value of?M≈165MeV on this plot.
In Fig.3,we show a sample plot of various sparticle contours in the m0?m3/2plane for two di?erent choices of the other parameter,namely tanβ.The sign ofμhas been taken to be positive. One of the very striking features of the minimal AMSB model is the strong mass degeneracy between the left and right charged sleptons.As a result of this,the third and the second generation L-R mixing angles become substantial.They can reach the maximal limit provided tanβis large.This large L-R mixing of the smuons has been shown to have a strong in?uence on the neutralino loop contribution(which is a rather small e?ect as compared to the dominant chargino loop contribution) to(g?2)μ[38]in the context of the minimal AMSB scenario.The corresponding constraint on the parameter space has been derived assuming that the supersymmetric contribution to(g?2)μis restricted within a2σlimit of the combined error from the Standard Model calculation and from the current uncertainty in the Brookhaven measurement[26-29].A similar constraint[26,28] from the measured radiative decay rateΓ(B→X sγ)has been invoked.
The top left corners of both the diagrams in Fig.3,marked by X,are not allowed.This is due to the twin requirements of?τ1not being allowed to be the LSP and m?τ
having to exceed the
1
experimental lower bound of70GeV[39].Any further increase in m3/2for a particular value of m0is disallowed since then the staus become tachyonic.Furthermore,the lower limit on m3/2in each?gure comes from the experimental constraint[37]m χ±1>86GeV.One can also check that the maximum possible value of m3/2for a given m0is a decreasing function of tanβ[38].Recently, new bounds on minimal AMSB model parameters have been proposed from the condition that the electroweak symmetry breaking minimum of the scalar potential is the deepest point in the?eld space[32].Selected parameters for our entire numerical calculation have been chosen so as to be consistent with all these bounds.
The continuous and dashed curved lines in Fig.3stand for contours of constant charged slepton and sneutrino masses respectively5.It is easy to see why the latter are lower than the former.The
Figure3:Contours of constant charged slepton(continuous)and sneutrino(dashed)masses in the m0?m3/2plane for(a)tanβ=10andμ>0,(b)tanβ=30andμ>0.The number adjacent to
each pair of curved lines corresponds to the sneutrino(slepton)mass for that particular contour. The dotted horizontal lines are the contours of constant χ02mass.The number adjacent to each horizontal line is the mass of χ02for that contour.The boundaries of constraint,labelled by FM and CHKLS(the near vertical boundary in(a)from(g?2)μand the near horizontal boundaries in (a)and(b)fromΓ(B→X sγ)),have been taken from Refs.[26]and[28]respectively.The shaded regions are the allowed regions in the two?gures.
sneutrino mass is linked with the left charged slepton mass through the SU(2)L relation
m2?ν=m2?
L +
1
where the mass of χ02is between that of the lighter stau?τ1and the?rst generation sleptons.This variant,which we call Spectrum B1,is characterized by
?Spectrum B1: χ01(≈ χ±1)
For most of the decay modes,the spectra B and B1have identical behaviour,and we do not list them separately.The only exception is the decay of χ02,which is discussed in Section3.2.
It can be seen from Fig.3that mass-orderings,other than A and B above,are allowed only in very restricted regions of the m3/2?m0plane and correspond to the?ne tuning of some parameters.
This is why we do not consider them further.As already mentioned,staus and smuons are not considered for production here.That is the reason why we have not included them in the two classes of spectrum written above.(However,for completeness,one may note that the smuons are almost degenerate with the selectrons,while the lighter stau is the lightest slepton for large values of tanβ).Finally,the regions in the parameter space,where the LSP can be either the?τ1(the two stau mass eigenstates are separated because of the large o?-diagonal terms in the stau mass matrix) or the sneutrino,are disfavoured on cosmological grounds.Such LSPs are also incompatible with the stability of the supersymmetric scalar potential[32].Thus,there are really only two distinct classes of spectra which are relevant and interesting for our present study.
3Production and Decays of Sparticles
The basic production processes that we consider are e+e?→?e±L?e?L,?e±R?e?R,?e±L?e?R,?νˉ?ν, χ01 χ02, χ02 χ02. We have not included the process e+e?→ χ±1 χ?1since that will yield two displaced vertices/soft pions in addition to E T/;the only way to trigger the reaction would be to consider an additional initial-state-radiated(ISR)photon[31].However,apart from the rate being lower by a factor α,such a signal could also come from the light higgsino(|μ|?|M1,2|)scenario.The process e+e?→χ+1χ?1γin the AMSB model has been discussed in Ref.[40].Another possible process that we have not considered is the heavier e+e?→ χ±1?χ±2since the dominant decay mode of?χ±2 in the AMSB scenario is?χ±2→ χ±1h and then the branching ratio for a?nal con?guration with multilepton+soft pion+E T/is rather small.
In this section we shall also enumerate all possible decay channels of the low-lying sparticles χ±1, χ02,?e L,?e R and?νthat result in one or more leptons plus at least one soft charged pion accompanied by missing energy.Let us highlight some important characteristics,selection criteria and conventions that we have used.
? χ±1and χ01are almost exclusively winos and χ±1decays slowly(with a visibly displaced vertex X D)only6to χ01+softπ±.
? χ02is almost a bino;at least,those decays that require a nonzero wino component of χ02are neglected,while the higgsino components are unimportant since we are considering only e or
μin the?nal state.An exception is made for χ02decay in spectrum B,and is discussed in section3.2.
?Whenever one or more two-body decay channels are kinematically allowed,we do not consider possible three-or four-body channels.Three-body channels,for instance,are signi?cant only when no two-body decay channel exists and are considered only in that situation.?Written without any su?x,?νandνindicate both electron and muon-type sneutrinos.Sim-ilarly,?(?1,?2)stands for e orμ.For simplicity,we do not consider anyτsignals.We use the same notation for both(s)neutrino and anti(s)neutrino;they can be discriminated from the charge of the associated(s)lepton.
3.1Decay cascade for Spectrum A
For Spectrum A,the allowed decay channels are as follows:
1. χ02→ν?ν,?±L???L,?±R???R.
2.?e L→e χ01,νe χ±1.
3.?e R→e χ0?2→eν?ν.Note that?e R must have a three-body decay since χ01has a vanishing bino
component.Also,the virtual χ0?2goes into theν?νchannel rather than the?±L???L channel since
??
L is never lighter than?e R in minimal AMSB.(In other AMSB models[16-18]where?e R is heavier than??L,this mode is also allowed.)However,theτ?τ1channel,though included in the calculation of the branching fractions of other channels,is not considered explicitly since we do not look at?nal states withτ’s.
4.?ν→ν χ01,?? χ±1.
This immediately predicts the decay cascade for low-lying sparticles.As already pointed out, χ±1results in a visibly displaced vertex X D and/or a soft charged pion.We club χ01,which invariably appears at the end in sparticle dacays,andνunder E T/.Thus,the end products of various sleptons and χ02are
1.?ν→?±π?E T/(it can have a completely invisible mode?ν→ν χ01and thus can act as a virtual
LSP).
2.?e L→eE T/,πE T/.
3.?e R→eE T/,e?±π?E T/.
4. χ02→?±π?E T/,?+??E T/,?+1??1?±2π?E T/(?1,?2=e,μ).
We focus on the following six production processes in an e+e?linear collider.Only those?nal states with one or two soft charged pions accompanied by at least one charged lepton and E T/are
enlisted;however,only states with one soft pion,and dileptons with two soft pions,are discussed in detail in the next section.Note that some of the possible?nal states,e.g.,?ve leptons and a soft pion,has negligibly small cross sections due to very small branching ratios in various stages of the cascade.
3.1.1Production processes
Process1:e+e?→?νˉ?ν:Possible?nal states here are?±π?or?+??π+π?.The leptonic?avour is the?avour of the produced?ν;if we consider only?νe pair production(which will be more copious than?νμpair production due to the t-channel?e L exchange diagram)the?nal state will have one or two electrons.
Process2:e+e?→?e+L?e?L:The only possible signal here is e±π?.
Process3:e+e?→?e+R?e?R:There can be two possible pionic?nal states in this case,namely, e+e??±π?,and e+e??±1??2π+π?.Note that here?1and?2may be di?erent since they come from the?avour-blind χ02decay.Thus,there are four possible combinations of two-pion?nal states. Process4:e+e?→?e±R?e?L:This process takes place only through the t-channel exchange of χ02. The corresponding?nal states are e±π?,e+e??±π?and e±??π+π?. Process5:e+e?→ χ01 χ02:The?nal state here is essentially that obtained from the cascade decay of χ02.We will focus on only two generic channels,namely,?±π?and?+1??1?±2π?(?1,?2=e,μ). Depending on the?avours of?1and?2,there are actually six channels. Process6:e+e?→ χ02 χ02:The pair production of χ02produces a rich variety of possible?nal states. Single pion?nal states include?±π?,?±1?+2??2π?and?±1?+2??2?+3??3π?.Note that every possible con?guration necessarily has an odd number of charged leptons.Depending on the leptonic?avour, one has twelve channels with single soft pions plus one or more charged leptons plus E T/.There are three two-pion?nal states with an even number of charged leptons:?±1??2π+π?,?±1?+2??2??3π+π?and?±1?+2??2?+3??3??4π+π?.These result in?fteen?avour-speci?c channels.
3.2Decay cascade for Spectrum B
The allowed decay channels for Spectrum B are as follows:
1.?e L→e χ01,e χ02,νe χ±1.
2.?e R→e χ02.Thus?e R has a more prompt decay in spectrum B than in spectrum A.
3.?ν→ν χ01,ν χ02,?? χ±1.
4. χ02does not have the two-body decay channel to a lepton and a slepton.Its dominant decay
modes are: χ02→ χ01h, χ02→ χ01Z, χ02→ χ±1W?,where h is the lightest CP-even Higgs scalar.The last two modes occur through the tiny wino and/or higgsino components of the predominantly binolike χ02.Still,they dominate over the three-body decay channels mediated by virtual sneutrinos or left charged sleptons: χ02→ν?ν?→νν χ01,ν?±π?01; χ02→?±L???L?→
?+?? χ01,?±νπ? χ01.Since an??R cannot decay into? χ01,any??R-mediated decay does not occur.The two-body modes are,of course,not kinematically suppressed;the mass limit of χ±1governs the minimum mass splitting of χ02and χ01and precludes any such suppression.
For Spectrum B1(see the last paragraph of Section2),the two body channel χ02→τ?τ1opens up,and the branching ratios of all the above-mentioned two-body channels get suppressed.
Since we are not looking at?nal states withτ’s,it would be hard to detect a χ02in this case.
The decay cascades for sleptons and gauginos are:
1. χ02→?±π?E T/,?+??E T/. χ02also has a virtual LSP mode χ02→νν χ01.The leptons come from
the decay of W and Z;h decays dominantly into bˉb andτˉτwhich we do not consider here.
Note that the three-body channels also give the same?nal states,albeit in a tiny fraction.
As discussed earlier,the branching ratios for these modes su?er a heavy suppression once we look at Spectrum B1.
2.?ν→?±π?E T/,?+??E T/(and the virtual LSP mode listed for spectrum A).
3.?e L→eE T/,πE T/,e?+??E T/,e?±π?E T/.
4.?e R→eE T/,e?+??E T/,e?±π?E T/.
Next,we enlist the signals for the pair production of charged sleptons and gauginos.As stated earlier,our signals consist of one or more charged leptons(but noτ)plus one or two soft charged pions,accompanied with E T/.
3.2.1Production processes
Process1:e+e?→?νˉ?ν:Possible one pion?nal states are?±π?and?+1??1?±2π?,where?1and ?2can both be e orμirrespective of the sneutrino?avour.Thus,there can be six?avour-speci?c ?nal states.The only possible two-pion?nal state is?±1??2π+π?,which actually is a combination of three?avour-speci?c channels.
Process2:e+e?→?e+L?e?L:The one-pion?nal states are?±π?,e+e??±π?,e±?+??π?,and e+e??+1??1?±2π?.Written in full,they indicate two one-lepton,three three-lepton and four?ve-lepton?nal states.The two-pion states are e±?±π?π?(note that in this case we may have a like-sign dilepton signal)and e+e??±1?±2π?π?(this will result in a four-lepton signal,with three of them of the same sign).
Process3:e+e?→?e+R?e?R:Right selectrons can only decay to χ02,so the possible one-pion signals are e+e??±π?and e+e??+1??1?±2π?.Altogether,they add up to six one-pion?nal states.The only possible two-pion state is e+e??±1?±2π?π?.
Process4:e+e?→?e±R?e?L:There are four generic one-pion?nal states for this associated pro-duction process,namely,e±π?,e+e??±π?,e±?±??π?and e+e??+1??1?±2π?,which result in eight ?avour-speci?c channels.The two-pion?nal states can be e±?±π?π?and e+e??±1?±2π?π?.
Process5:e+e?→ χ01 χ02:There is only one possible channel,viz.?±π?. Process6:e+e?→ χ02 χ02:Possible one-pion channels are?±π?and?+1??1?±2π?,resulting in six channels altogether.
In the three-lepton channel,two leptons of opposite sign and identical?avour should have their invariant mass peaked at m Z.The only possible two-pion channel is?±1?±2π?π?.Note that this decay may also give a like-sign dilepton signal.
Spectrum Parent Channels
eπ
μπ
e e?π
μμ?π
?1?1?2?2?3π
?νˉ?ν,?e L?e L,?e L?e R, χ01 χ02, χ02 χ02
?νˉ?ν,?e L?e L, χ01 χ02, χ02 χ02
B?e R?e R,?e L?e R,?e L?e L,?νˉ?ν, χ02 χ02
(?1,2=e,μ)
χ02 χ02,?νˉ?ν
?e L?e L,?e R?e R,?e L?e R(?1,2=e,μ)
Table1:Possible one or multilepton signal with one soft pion.All possible combinations of leptonic ?avours are to be taken into account where the?avour is not shown explicitly.
A list of all possible?nal states and their parent sparticles,as discussed above,for both Spectra A and B,is given in Table1for one pion channels.A similar list is given in Table2for two pion channels.In the next section,we discuss some of the one-pion signals and the dilepton plus dipion signal,in detail,but let us note a few key features right at this point.
?One can sometimes have the same signal for Spectrum A or B;however,their sources are di?erent.This means that the production cross-section and di?erent distributions will also vary from one spectrum to the other;this may help discriminate between them.A useful option may be to use one polarized beam when some of the channels would be altogether ruled out.
?One must have an odd(even)number of charged leptons produced in conjunction with one (two)soft pion(s)in order to maintain charge neutrality.However,one can have a maximum of?ve leptons in the one-pion channel for both Spectra A and B.On the other hand,for two-pion channels,Spectrum A allows at most six charged leptons,while Spectrum B allows only four.The signal cross sections of the multilepton channels(with lepton number≥4)
√may,however,be unobservably small with the presently designed luminosity of a
Signals
?νˉ?ν,?e L?e R, χ02 χ02
?νˉ?ν, χ02 χ02
A?e R?e R, χ02 χ02(?1,2=e,μ)
χ02 χ02 χ02 χ02
e?ππ
μμππ
e e?1?2ππ
?e L.First,note that the decay?e R→?e L plus a virtual higgsino-type neutralino is suppressed both due to its mass and the selectron coupling of the latter.It need not be considered.We can then discuss the three following scenarios:
?Spectrum A′: χ01(≈ χ±1)
?Spectrum A′′: χ01(≈ χ±1)
?Spectrum B′: χ01(≈ χ±1)< χ02
In spectrum A′,only?e R acquires a new decay channel,viz.,?e R→e?+??E T/.This is because the virtual χ0?2can now decay into a left charged slepton,which is lighter than the corresponding right charged slepton.Thus,one may have a5?+πsignal from the pair production of?e R.In spectrum A′′,?e R has the two-body decay to?e R→e χ02.Apart from the fact that the lifetime of?e R is signi?cantly shorter in this model as compared to spectrum A,the?nal products are identical (assuming that?e R,the heaviest low-lying charged slepton,is within the kinematic reach of the machine).The decay pattern of spectrum B′is identical to that of spectrum B since the pattern for the latter does not depend upon the degeneracy of?e L and?e R.
4Numerical results and discussions
Cross sections for the production of various two-sparticle combinations have been calculated at an e+e?CM energy of1TeV for two values of tanβ,namely,10and30,forμ>0.Here,we would like to point out that in our parton level Monte Carlo simulation we have not taken into account the ISR and beamstrahlung e?ects.The said cross sections,computed under this condition,were multiplied by the proper branching fractions of the corresponding decay channels to get the?nal states described in https://www.doczj.com/doc/149732978.html,ing to numbers,the selection cuts that have been used on the decays products are as follows:
?The transverse momentum of the lepton(s)p?T>5GeV.
?The pseudorapidities of the lepton(s)and of the pion|η|<2.5.
?The electron-pion isolation variable?R=
needs to add the contributions from all the individual channels as mentioned earlier.The total normalized distribution can be expressed as:
1 dX =
n
i=11dX(11)
Spectrum m0(GeV)tanβ
(a)44
(b)42
(c)39
(d)46
(e)44
(f)47
33010
35010
B36010
46030
47530
51030
Table3:Selected parameter points withμ>0for computed cross sections.
In Eq.11,X can be the transverse momentum p e T of the electron,the decay length L of the chargino or the soft pion transverse momentum pπT and i runs from1to6,covering all pro-cesses which give rise to this distribution.The electron p T distribution corresponding to the signal e±π?E T/,for spectrum A,is shown in Fig.4(a)and demonstrates a very wide distribution.This highly energetic electron can be used to trigger such events.After that one can look for the heavily ionizing charged track by the chargino ending in a soft pion in the Silicon Vertex Detector(SVD) located very close to the beam pipe.For this purpose,the knowledge of the chargino decay length is very important.The probability that the chargino decays before travelling a distanceλis given by P(λ)=1?exp(?λ/L),where L=cτ(βγ)is the average decay length of the chargino.From this,one can generate the actual decay length distribution of the chargino asλ=?L ln[1?P(λ)], where P(λ)is generated by a random number between0and1.In Fig4(b),we have displayed the chargino decay length distribution with the selection cuts mentioned above.Though most of the events in this?gure cluster at lower decay lengths for which the χ±1decay would be so prompt as to make the charged track invisible(in this case the end product softπwill still be detectable),a substantial number of events do have reasonably large decay lengths for which X D may be visible. In case the chargino track is not seen,our signal can still be observed by looking at the soft pion
impact parameter bπwhich is determined primarily by the chargino decay length and?M.It turns out that,for our chosen point in the AMSB parameter space,the soft pion impact parameter is always signi?cantly above the value where it can be resolved(b res～0.1cm).Hence,the prospects
of resolving the impact parameter of the soft pion are quite high.The normalized p T distribution of the soft pion has been shown in Fig4(c).Most of the events peak at the lower pπT<200MeV, which can be understood from the value of?M for this point in the parameter space.The impo-sition of selection cuts on the soft pion kills the peak of the distribution.Nevertheless,we are left with a substantial number of events,which can be observed.The distribution looks quite similar for Spectrum B and is not shown here.
Signal
?νˉ?ν?e Rˉ?e R χ01ˉ χ02Total
a46.70.0140.655
29.51- 3.578.85
c44.440.0230.616
21.6- 1.8655.26
e24.33 2.57×10?50.05
12.36-0.5326.33
a-0.0110.238
- 3.65×10?4 1.60 1.86
c-0.0180.166
-0.000.0140.049
e- 2.57×10?50.008
-0.000.0070.008
a-0.00730.070
36.22--36.31
c-0.0130.079
23.72--23.73
e- 2.57×10?50.0059
14.48--14.48
Tables4and5,numbers for the cross sections in the three channels mentioned above are displayed for the spectra A and B respectively with the AMSB parameter points as selected in Table3.The individual processes have widely di?erent contributions to these channels because of the fact that their individual production cross sections and branching ratios in the cascade decays are highly parameter dependent.For example,for the AMSB input(a)of spectrum B,
Signal
?νˉ?ν?e Rˉ?e R χ01ˉ χ02Total a63.870.0680.029
39.03-0.33393.80
c49.300.07110.027
eπ+E T/11.86-0.04123.31 d7.900.0130.0008
3.98-0.040 5.82
6.8×10?70.037-0.68
b0.0130.7380.009
6.6×10?50.044-0.77
d 1.9×10?40.094 1.6×10?4
1.5×10?57.0×10?4-0.10
f 1.5×10?40.066 1.2×10?4
62.63--63.81
b0.021 1.160.172
49.9--51.16
d 2.4×10?40.1130.002
10.6--10.73
f 1.75×10?40.0750.001
Table5:Some selected signals in Spectrum B for sample choices of parameters in Table3.The contributions from di?erent sources are also shown in the Table.Cross sections less that10?4are not added to the total cross section.Here,PS stands for Parameter Set.
?BR.(?νe→e?+ χ±1)～79%
?BR.(?νe→ν+ χ01)～20%
?BR.(?νe→ν+ χ02)～2.9×10?4%
?BR.( χ02→ χ01+h0)～10.8%
?BR.( χ02→ χ±1+W?)～77.3%
play a part (in) 重要程度：★☆☆☆☆难易程度：★★☆☆☆ Have you realized the part computers have ___________ in the daily life? A. made B. given C. caused D. played 【参考答案】D 【拓展延伸】 1. play a part (in) 在……中扮演一个角色；参与；在……中起作用 2. play the role of 扮演……的角色 play an important role / part in...在……中起重要作用 play the leading role / part主演；起带头作用 3. take part in 参加 for the most part多半；在很大程度上 for one’s part就某人而言，对某人来说 1. Colors play an important ___________ in the way you look. A. part B. form C. effect D. pride 2. Mr. Huang will ___________ in the movement. A. play a leading part B. take parts C. play leading part D. take a part 3. __________ part that women ___________ in society is great. A. The; plays B. A; takes C. A; plays
【摘要】黄自先生是我国杰出的音乐家，他以艺术歌曲的创作最为代表。而黄自先生特别强调了钢琴伴奏对于艺术歌曲组成的重要性。本文是以黄自先生创作的具有爱国主义和人道主义的艺术歌曲《天伦歌》为研究对象，通过对作品分析，归纳钢琴伴奏的弹奏方法与特点，并总结黄自先生的艺术成就与贡献。 【关键词】艺术歌曲；和声；伴奏织体；弹奏技巧 一、黄自艺术歌曲《天伦歌》的分析 （一）《天伦歌》的人文及创作背景。黄自的艺术歌曲《天伦歌》是一首具有教育意义和人道主义精神的作品。同时，它也具有民族性的特点。这首作品是根据联华公司的影片《天伦》而创作的主题曲，也是我国近代音乐史上第一首为电影谱写的艺术歌曲。作品创作于我国政治动荡、经济不稳定的30年代，这个时期，这种文化思潮冲击着我国各个领域，连音乐艺术领域也未幸免――以《毛毛雨》为代表的黄色歌曲流传广泛，对人民大众，尤其是青少年的不良影响极其深刻，黄自为此担忧，创作了大量艺术修养和文化水平较高的艺术歌曲。《天伦歌》就是在这样的历史背景下创作的，作品以孤儿失去亲人的苦痛为起点，发展到人民的发愤图强，最后升华到博爱、奋起的民族志向，对青少年的爱国主义教育有着重要的影响。 （二）《天伦歌》曲式与和声。《天伦歌》是并列三部曲式，为a+b+c，最后扩充并达到全曲的高潮。作品中引子和coda所使用的音乐材料相同，前后呼应，合头合尾。这首艺术歌曲结构规整，乐句进行的较为清晰，所使用的节拍韵律符合歌词的特点，如三连音紧密连接，为突出歌词中号召的力量等。 和声上，充分体现了中西方作曲技法融合的创作特性。使用了很多七和弦。其中，一部分是西方的和声，一部分是将我国传统的五声调式中的五个音纵向的结合，构成五声性和弦。与前两首作品相比，《天伦歌》的民族性因素增强，这也与它本身的歌词内容和要弘扬的爱国主义精神相对应。 （三）《天伦歌》的伴奏织体分析。《天伦歌》的前奏使用了a段进唱的旋律发展而来的，具有五声调性特点，增添了民族性的色彩。在作品的第10小节转调入近关系调，调性的转换使歌曲增添抒情的情绪。这时的伴奏加强和弦力度，采用切分节奏，节拍重音突出，与a段形成强弱的明显对比，突出悲壮情绪。 c段的伴奏采用进行曲的风格，右手以和弦为主，表现铿锵有力的进行。右手为上行进行，把全曲推向最高潮。左手仍以柱式和弦为主，保持节奏稳定。在作品的扩展乐段，左手的节拍低音上行与右手的八度和弦与音程对应，推动音乐朝向宏伟、壮丽的方向进行。coda 处，与引子材料相同，首尾呼应。 二、《天伦歌》实践研究 《天伦歌》是具有很强民族性因素的作品。所谓民族性，体现在所使用的五声性和声、传统歌词韵律以及歌曲段落发展等方面上。 作品的整个发展过程可以用伤感――悲壮――兴奋――宏达四个过程来表述。在钢琴伴奏弹奏的时候，要以演唱者的歌唱状态为中心，选择合适的伴奏音量、音色和音质来配合，做到对演唱者的演唱同步，并起到连接、补充、修饰等辅助作用。 作品分为三段，即a+b+c+扩充段落。第一段以五声音阶的进行为主，表现儿童失去父母的悲伤和痛苦，前奏进入时要弹奏的使用稍凄楚的音色，左手低音重复进行，在弹奏完第一个低音后，要迅速的找到下一个跨音区的音符；右手弹奏的要有棱角，在前奏结束的时候第四小节的t方向的延音处，要给演唱者留有准备。演唱者进入后，左手整体的踏板使用的要连贯。随着作品发展，伴奏与旋律声部出现轮唱的形式，要弹奏的流动性强，稍突出一些。后以mf力度出现的具有转调性质的琶音奏法，要弹奏的如流水般连贯。在重复段落，即“小
我国艺术歌曲钢琴伴奏-精 2020-12-12 【关键字】传统、作风、整体、现代、快速、统一、发展、建立、了解、研究、特点、突出、关键、内涵、情绪、力量、地位、需要、氛围、重点、需求、特色、作用、结构、关系、增强、塑造、借鉴、把握、形成、丰富、满足、帮助、发挥、提高、内心 【摘要】艺术歌曲中，伴奏、旋律、诗歌三者是不可分割的重 要因素，它们三个共同构成一个统一体，伴奏声部与声乐演唱处于 同样的重要地位。形成了人声与器乐的巧妙的结合，即钢琴和歌唱 的二重奏。钢琴部分的音乐使歌曲紧密的联系起来，组成形象变化 丰富而且不中断的套曲，把音乐表达的淋漓尽致。 【关键词】艺术歌曲；钢琴伴奏；中国艺术歌曲 艺术歌曲中，钢琴伴奏不是简单、辅助的衬托，而是根据音乐 作品的内容为表现音乐形象的需要来进行创作的重要部分。准确了 解钢琴伴奏与艺术歌曲之间的关系,深层次地了解其钢琴伴奏的风 格特点,能帮助我们更为准确地把握钢琴伴奏在艺术歌曲中的作用 和地位，从而在演奏实践中为歌曲的演唱起到更好的烘托作用。 一、中国艺术歌曲与钢琴伴奏 “中西结合”是中国艺术歌曲中钢琴伴奏的主要特征之一，作 曲家们将西洋作曲技法同中国的传统文化相结合，从开始的借鉴古 典乐派和浪漫主义时期的创作风格，到尝试接近民族乐派及印象主 义乐派的风格，在融入中国风格的钢琴伴奏写作，都是对中国艺术 歌曲中钢琴写作技法的进一步尝试和提高。也为后来的艺术歌曲写 作提供了更多宝贵的经验，在长期发展中，我国艺术歌曲的钢琴伴 奏也逐渐呈现出多姿多彩的音乐风格和特色。中国艺术歌曲的钢琴
写作中，不可忽略的是钢琴伴奏织体的作用，因此作曲家们通常都以丰富的伴奏织体来烘托歌曲的意境，铺垫音乐背景，增强音乐感染力。和声织体，复调织体都在许多作品中使用，较为常见的是综合织体。这些不同的伴奏织体的歌曲，极大限度的发挥了钢琴的艺术表现力，起到了渲染歌曲氛围，揭示内心情感，塑造歌曲背景的重要作用。钢琴伴奏成为整体乐思不可缺少的部分。优秀的钢琴伴奏织体，对发掘歌曲内涵，表现音乐形象，构架诗词与音乐之间的桥梁等方面具有很大的意义。在不断发展和探索中，也将许多伴奏织体使用得非常娴熟精确。 二、青主艺术歌曲《我住长江头》中钢琴伴奏的特点 《我住长江头》原词模仿民歌风格，抒写一个女子怀念其爱人的深情。青主以清新悠远的音乐体现了原词的意境，而又别有寄寓。歌调悠长，但有别于民间的山歌小曲；句尾经常出现下行或向上的拖腔，听起来更接近于吟哦古诗的意味，却又比吟诗更具激情。钢琴伴奏以江水般流动的音型贯穿全曲，衬托着气息宽广的歌唱，象征着绵绵不断的情思。由于运用了自然调式的旋律与和声，显得自由舒畅，富于浪漫气息，并具有民族风味。最有新意的是，歌曲突破了“卜算子”词牌双调上、下两阕一般应取平行反复结构的惯例，而把下阕单独反复了三次，并且一次比一次激动，最后在全曲的高音区以ff结束。这样的处理突出了思念之情的真切和执著，并具有单纯的情歌所没有的昂奋力量。这是因为作者当年是大革命的参加者，正被反动派通缉，才不得不以破格的音乐处理，假借古代的
play a part in的用法 Do you know this pretty girl Right! She is Audrey Hepburn who played many classic roles in a great many famous films. For example, < Roman Holiday> is the one of the films which earned Hepburn her first Academy Award for Best Actress. Audrey Hepburn played the part/role of Princess Ann in this film. play the part/role of…扮演……角色
Audrey Hepburn played a leading part in
Audrey Hepburn also played leading roles in < Funny Face>and < My Fair Lady〉.( My Fair Lady 窈窕淑女影片讲述下层卖花女被语言学教授改造成优雅贵妇的故事，从头至尾洋溢着幽默和雅趣 .Funny Face 甜姐儿) Play a role in…在……中扮演角色，在……中起作用 play a part/role in doing sth. 在做某事方面起作用,参与做某事 We can?all?play?a?role/part?in?reducing?our?dependence?on?plastic, if we started to?take some small?steps?in?our?everyday?lives?to?be
Unit 7 Will people have robots?知识 点整理 Unit7willpeoplehaverobots?知识点整理 一、词组、短语： 、oncomputers在电脑上， 2、onpaper在纸上， 3、livetobe200yearsold活到200岁， 4、freetime空闲时间， 5、indanger 在危险中， 6、ontheearth在世界上 7、playapartinsth在某方面出力/做贡献， 8、spacestation太空站， 8、lookfor寻找， 9、computerprogrammer电脑程序师， 10、inthefuture 在将来， 11、hundredsof成百上千的， 12、thesame…as与…一样， 13、overandoveragain反复， 14、getbored 无聊，
15、wakeup醒来/唤醒， 16、looklike 看起来像， 17、falldown倒下/落下 二、重要句子（语法） 、will+动词原形 将要做 2、fewer/more+可数名词复数更少/更多… 3、less/more+不可数名词 更少/更多 4、trytodosth. 尽力做某事 5、havetodosth 不得不做某事 6、agreewithsb. 同意某人的意见 7、such+名词（词组） 如此
8、playapartindoingsth 参与做某事 9、makesbdosth 让某人做某事 10、helpsbwithsth 帮助某人做某事 11、Therewillbe+主语+其他 将会有…. 12、Thereis/are+sb.+doingsth 有…正在做… 13、Itis +形容词+forsb+todosth 做某事对某人来说… 语法： whatwillthefuturebelike? citieswillbemorepolluted.Andtherewillbefewertrees. willpeopleusemoneyin100years?
人教版八年级英语上册Unit7知识点归纳整 理 Unit7illpeoplehaverobots? 短语归纳 onputer在电脑上2.onpaper在纸上3.aeup醒 livetodo200yearsold活动200岁5.freetie空闲时间indanger处于危险之中7.ontheearth在地球上 playapartinsth.参与某事9.inthefuture在未 0spacestation太空站11.puterprograer电脑编程员 loofor寻找13.hundredsof许多；成百上千 thesae…as…与……一样15.getbored感到厌烦的 overandoveragain多次；反复地17.falldon倒塌 ill+动词原形将要做…… feer/ore+可数名词复数更少/更多…… 0.less/ore+不可数名词更少/更多…… 1.havetodosth.不得不做某事 2.agreeithsb.同意某人的意见 3.such+名词如此…… playapartindoingsth.参与做某事 Thereillbe+主语+其他将会有…… Thereis/are+sb./sth.+doingsth.有……正在做某事
aesb.dosth.helpsb.ithsth.帮助某人做某事 trytodosth.尽力做某事 It’s+ad+forsb.todosth.对某人来说，做某事……的。 语法讲解 Boosillonlybeonputers,notonpaper.书将只在电脑里，而不是在纸上。 Thereillbeorepollution.将会有更多的污染。 ).Thereillbe+n=Thereis/aregoingtobe+n将会有…ThereisgoingtobeafootballatchthisFriday. ).pollution:污染；公害pollute：污染；弄脏polluted：受污染的 Everyoneshouldplayapartinsavingtheearth.每个人应该参与挽救地球。 Todaytherearealreadyrobotsoringinfactories.现在已经有机器人在工厂里工作了。 Therebesb.doingsth.有某人正在做…Thereisabirdsinginginthetree. Theyagreeitaytaehundredsofyears.他们同意这可能花费几百年的时间。 Ittaes+时间+todosth.某人花费时间区做某事。 Ittooehalfanhourtofinishyhoeor. agreetodosth.eagreetoeetuplaterandtalthingsover
XX九年级英语上册Unit13教案（新版人教 版） 学科English年级9班级 课型fresh课时1/6媒体ataperecorder,cAI 课题Unit13e’retryingtosavetheearth!SectionA1a~1c 话题Protectingtheenvironent 功能Talaboutpollutionandenvironentalprotection 教 学 目 标 知识 技能1.Targetlanguage: e’retryingtosavetheearth. Peoplearethroinglitterintotheriver. Theriverusedtobesoclean. Everyoneshouldhelptocleanuptheriver. Graar: Presentprogressive,usedto,odalverbs ordsandexpressions;
curriculuords:litter,botto,fisheran Usefulexpressions:befullof,put…into,thro…into,cleanup,playapartin,closedon 过程 方法Accordingtodesigningsoetass,totrainstudents’listeningabilityandtotrainstudents’unicativepetence． 情感 态度Everyoneshouldeepourriversclean. 学习策略Listeningforeyords,transforinginforation. 重点TargetLanguage 难点1．Hototrainstudents’listeningability． ．Hototrainstudents’unicativepetence． 教学内容及问题情境学生活动设计意图 a.TointroduceSstotheunitgoal,talaboutpollutionanden vironentalprotection. Picture: Thefourpicturesshodifferentforsofenvironentalpollut
八年级上册英语单元知识点归纳 Unit1Wheredidyougoonvacation? 短语归纳 1.goonvacation去度假 2.stayathome待在家里 3.gotothemountains去爬山 4.gotothebeach去海滩 5.visitmuseums参观博物馆 6.gotosummercamp去参加夏令营 7.quiteafew相当多 8.studyfortests为测验而学习 9.goout出去10.mostofthetime大部分时间11.haveagoodtimedoing=havefundoing=enjoyoneself玩得高兴 去购 物because+句子 查明22.goon上上下下 用法： 3.nothing 4.seem+ 13.dislikedoingsth.不喜欢做某事 14.keepdoingsth.继续做某事keepondoingsth不停做某事 15.Whynotdo.sth.=whydon’tyoudosth为什么不做……呢？ 16.so+adj.+that+从句如此……以至于…… 17.tellsb.(not)todosth.告诉某人（不要）做某事 18.enough+名词，形容词+enough 19.notreally.真的没有。 20.seemtodosth似乎好像做某事 21.Byefornow!到这该说再见了。
22.Howdoyoulike…=Whatdoyouthinkof…=Whatdoyouthinkabout… Unit2Howoftendoyouexercise? 短语 1.helpwithhousework帮助做家务 2.onweekends=ontheweekend在周末 3.howoften多久 一次howsoon多久（回答in10years）4.hardlyever几乎从不 5.onceaweek每周一次twiceamonth每月两次everyday每天three/four…timesaweek每周三四…次 6.befree=beavailable有空 7.gotothemovies去看电影 https://www.doczj.com/doc/149732978.html,etheInternet用互联网ontheInternet在网上surftheInternet 上网 9.swingdance摇摆舞10.playtennis打网球play+ 球类/棋类/中国乐器playthe+西洋乐器11.stayuplate熬夜；睡得很晚12.atleast至少atmost最多 擅长 根本firstofall 21.suchas看牙医 用法 少…? 5.主语 7.It’ 10.What Unit3I 短语 和……相同；与……一致bedifferentfrom与……不同5.careabout关心；介意takecareof=lookafter照顾6.belikeamirror像一面镜子7.themostimportant最重要的8.aslongas只要；既然 9.bringout使显现；使表现出10.getbettergrades取得更好的成绩11.reachfor伸手取12.infact 事实上；实际上13.makefriends交朋友14.one…,theother…一个…，另一个15.touchone’sheart 感动某人16.betalentedinmusic有音乐天赋 17.shareeverything分享一切18.talkabout谈论19.primaryschoolstudents小学生middleschoolstudent中学生https://www.doczj.com/doc/149732978.html,rmation是不可数名词，一则消息：apieceofinformation 21.theEnglishstudycenter英语学习中心 用法
XX八年级英语上册第七单元导学案（人 教版） 本资料为woRD文档，请点击下载地址下载全文下载地址Unit7 willpeoplehaverobots? Period8 SectionBSelfcheck 教师复备栏或 学生笔记栏 【学习目标】 .熟练掌握本单元词汇： 2.熟练掌握本单元句型： 5） In20years，IthinkI’llbeanewspaperreporter. ontheweekend,I’lllooklesssmartbutIwillbemorecomfortable. whatwillyour…belike? 【学习重点 难点】 本单元的单词、短语、语法 【学法指导】 及时练习与巩固
【教学过程】 一、 导入（启发探究 3分钟） 对话复习： Nick:whatareyoureading,jill? jill:It’sbookaboutfuture. Nick:Soundscool.Sowhatwillthefuturebelike? jill:well,citieswillbemorecrowdedandpolluted.Therew illbefewertreesandtheenvironmentwillbeingreatdanger. Nick:Thatsoundsbad!willwehavetomovetootherplanets. jill:maybe.ButIwanttoliveontheearth. Nick:me,too.Thenwhatcanwedo? jill:wecanuselesswaterandplantsmoretrees.Everyonesh ouldplayapartinsavingtheearth. 二、自学（自主探究 6分钟） 用法：
八年级英语上册Unit7 Will people have robots?知识点归纳 课 件www.5y https://www.doczj.com/doc/149732978.html,八年级英语上册Unit7willpeoplehaverobots?知识点归纳 八年级上Unit7willpeoplehaverobots? oncomputer在电脑上 onpaper在纸上 livetodo200yearsold活动200岁 freetime空闲时间 indanger处于危险之中 ontheearth在地球上 playapartinsth.参与某事 spacestation太空站 lookfor寻找 computerprogrammer电脑编程员 inthefuture在未来 hundredsof许多；成百上千 thesame…as…与……一样 overandoveragain多次；反复地 getbored感到厌烦的
wakeup醒来 falldown倒塌will+动词原形 将要做…… fewer/more+可数名词复数 更少/更多……less/more+不可数名词 更少/更多…… havetodosth.不得不做某事 agreewithsb.同意某人的意见 such+名词（词组） 如此…… playapartindoingsth.参与做某事 Therewillbe+主语+其他 将会有…… Thereis/are+sb./sth.+doingsth.有……正在做某事makesb.dosth.使某人做某事 helpsb.withsth.帮助某人做某事 trytodosth.尽力做某事 It’s+adj.+forsb.todosth. 对某人来说，做某事……的。 1.ThestudentsinourschoollearnEnglish computers. A.at
八年级英语上册Unit7Willpeoplehaverobots?知识点归纳puters在电脑上， 2、onpaper在纸上， 3、livetobe200yearsold活到200岁， 4、freetime空闲时间， 5、indanger在危险中， 6、ontheearth在世界上 7、playapartinsth在某方面出力/做贡献， 8、spacestation太空站， 8、lookfor寻找， 9、computerprogrammer电脑程序师， 10、inthefuture在将来， 11、hundredsof成百上千的， 12、thesame…as与…一样， 13、overandoveragain反复， 14、getbored无聊， 15、wakeup醒来/唤醒， 16、looklike看起来像， 17、falldown倒下/落下 二、重要句子（语法） 1、will+动词原形将要做
2、fewer/more+可数名词复数更少/更多… 3、less/more+不可数名词更少/更多 4、trytodosth.尽力做某事 5、havetodosth不得不做某事 6、agreewithsb.同意某人的意见 7、such+名词（词组）如此 8、playapartindoingsth参与做某事 9、makesbdosth让某人做某事 10、helpsbwithsth帮助某人做某事 11、Therewillbe+主语+其他将会有…. 12、Thereis/are+sb.+doingsth有…正在做… 13、Itis+形容词+forsb+todosth做某事对某人来说…语法： Whatwillthefuturebelike? Citieswillbemorepolluted.Andtherewillbefewertrees. Willpeopleusemoneyin100years? No,theywon’t.Everythingwillbefree. Willtherebeworldpeace? Yes,Ihopeso. Kidswillstuffyathomeoncomputers. Theywon’tgotoschool.
八上英语复习重点总结 Unit1Wheredidyougoonvacation? 单元重点： 1）一般过去时 2）不定代词的用法： a)不定代词作主语，谓语动词用单三 b)形容词修饰不定代词要放在其后 c)something一般用在肯定句中，anything一般用在否定句和疑问句中重点词组： goonvacation去度假stayathome待在家里gotothemountains去爬山gotothebeach去海滩visitmuseums参观博物馆gotosummercamp去参观夏令营quiteafew相当多 studyfor为……而学习 goout出去 mostofthetime大部分时间tastegood尝起来很好吃ofcourse当然 feellike给……的感觉/想要inthepast在过去walkaround四处走走becauseof因为onebowlof…一碗……thenextday第二天 drinktea喝茶 findout找出；查明 goon继续 takephotos照相somethingimportant重要的事upanddown上上下下 comeup出来
用法集锦： 1）buysth.forsb./buysb.sth.为某人买某物 2）taste+adj.尝起来……look+adj.看起来…… 3）nothing…but+动词原形除了……之外什么都没有 4）seem+（tobe）+adj.看起来…… 你还能想到seem的什么用法？ 5）arrivein+大地点/arriveat+小地点到达某地 6）decidetodosth.决定去做某事 7）try的用法： 作动词：trydoingsth.尝试做某事/trytodosth.尽力去做某事tryone’sbesttodosth. 作名词：haveatry 8)forgetdoingsth.忘记做过某事/forgettodosth.忘记做某事 9)enjoydoingsth.喜欢做某事 10)dislikedoingsth.不喜欢做某事 11)Whynotdo.sth.?为什么不做……呢？ 12)So+adj.+that+从句如此……以至于…… 13)tellsb.(not)todosth.告诉某人（不要）做某事 14)总结keep的用法 Unit2Howoftendoyouexercise? 单元重点： 1）关于how的词组 2）频率副词的位置：放在be动词、助动词、情态动词之后，实意动词之前 3)Howoften与Howman ytimes的区别？ 重点词组： helpwithhousework帮助做家务onweekends/ontheweekend在周末