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Are Messages of R-parity Violating Supersymmetry Hidden
within Top Quark Signals ?Aseshkrishna Datta ?and Biswarup Mukhopadhyaya ?Mehta Research Institute,Chhatnag Road,Jhusi,Allahabad -211019,India (February 1,2008)Abstract In an R-parity nonconserving supersymmetric theory,the lighter stop can dominantly decay into bμand bτif R-parity breaking has to explain the neutrino mass and mixing pattern suggested by the data on atmospheric muon neutrinos.This should give rise to dilepton +dijet and single ?lepton +jets ,signals identical with those of the top quark at the Fermilab Tevatron.One can thus constrain the stop parameter space using the current top search data,and similarly look for the ?rst signals of supersymmetry at the upgraded runs of the Tevatron.
PACS numbers:12.60.Jv,14.65.Ha,14.80.Ly
Typeset using REVT E X
It has been repeatedly suggested that in a supersymmetric(SUSY)scenario[1],one of the two spin-zero superpartners of the top quark,popularly known as stop,could be considerably lighter than any other strongly interacting superparticle[2].This happens due to the mixing between the left-and right chiral stops,which can be quite large in principle,reducing the mass of the lighter eigenstate.Also,negative contribution from Yukawa coupling in the evolution equations for scalar mass parameters can cause the stop to be lighter than the other squarks in a framework where all squark?avours have the same mass at a high energy scale.It has been shown that in the minimal supersymmetric standard model(MSSM),a light stop(?t1)will decay dominantly through the channels?t1→cχ01and?t1→bχ+1,whereχ01 andχ+1are the lightest neutralino and the lighter chargino respectively.Out of these,the former reigns supreme[3]if the light stop is even lighter thanχ+1[4].Based on the ensuing signals,experiments at the Fermilab Tevatron have set a lower limit of about120?135GeV on the lighter stop[5]depending on the mass of the lightest neutralino.
The observed signals can be quite di?erent when R-parity,de?ned as(?1)3B+L+2S,is not a conserved quantity,something that is both theoretically and phenomenologically consistent in supersymmetric theories so long as only one of baryon number(B)and lepton number (L)is violated.In such cases,the lightest supersymmetric particle(LSP)can be unstable, thereby altering the signals of SUSY[6,7].If,in addition,the LSP(which is the lightest neutralino in most theories)is massive enough to evade searches at the large electron-positron collider(LEP),then the observation of SUSY at the Fermilab Tevatron may depend squarely on the production and decays of the light stop for whom R-parity violation opens up new and often dominant decay modes.The limits based on?t1→cχ01require re-examination in such a case.
In this letter,we want to point out that the easiest identi?able signatures of a light stop (and therefore perhaps of SUSY itself)in an R-parity nonconserving framework could be in?nal states that have been,and still are,widely studied to look for the top quark at the Tevatron,namely,the dimuon+dijet as well as single muon+jets signals.We further argue that stop decays leading to such?nal states are imperative in R-parity violating scenarios
that lead to neutrino masses and mixing as required by the recent SuperKamiokande(SK) data on atmospheric muon neutrinos.Thus a careful reanalysis of the already existing Tevatron Run I results on top search may allow us to explore a large region of the light stop parameter space of such theories,where the search channel employed for MSSM is not going to be e?ective.In Run II one can have an even wider prospect,not only for constraining the SUSY parameter space but also for the possibility of top signals being actually faked by the stop.In addition,some new signals for such models,very similar to those of the top quark,are suggested here.
Expressed in terms of the quark,lepton and Higgs super?elds,the MSSM superpotential is
W MSSM=μ?H1?H2+h l ij?L i?H1?E c j+h d ij?Q i?H1?D c j+h u ij?Q i?H2?U c j(1)
whereμis the Higgsino mass parameter and the last three terms give all the Yukawa inter-actions.
The possible additions to this superpotential due to R-parity violation(through lepton number violation only)are given by[6]
W L=?i?L i?H2+λijk?L i?L j?E c k+λ′ijk?L i?Q j?D c k(2)
We consider only the e?ects of the trilinear additional terms in the superpotential;we shall point out at the end of the paper that the e?ects we are suggesting can arise also from the bilinear terms?i?L i?H2.
If the SK data[8]on atmospheric muon neutrinos(and also similar data from the Soudan-II[9]and MACRO[10]experiments)have to be explained in terms ofνμ?ντoscillations, then the mass-squared splitting between the second and third lightest physical neutrino states will have to be?m223?5×10?3,in addition to near-maximal mixing between the corresponding?avour eigenstates.R-parity violation in the form of theλ-andλ′-type interactions in equation2can give rise to neutrino mass terms at one-loop level,the generic expression for them(in the?avour basis)being
(m loop
ν)ij?3m2
?q
λ′ikpλ′jpk
+
1
m2?
l
λikpλjpk(3)
where m d(l)denote the down-type quark(charged lepton)masses.m2?
l
,m2?q are the average slepton and squark mass squared.M SUSY(～μ)is the e?ective scale of supersymmetry breaking.The mass and mixing patterns suggested by the observedνμdata can be accom-modated in the above scheme of mass generation if,with M SUSY?m?q?300?500GeV,λ′233?λ′333?a few times10?4[11].An immediate consequence of such couplings is the decay of the lighter stop in the channels?t1→bτ+and?t1→bμ+with comparable widths.
There is a considerably large region of the parameter space,not yet constrained by any experimental data,where the stop is the second lightest supersymmetric particle next to the lightest neutralino.In this region,the three lowest-order decay channels available to the stop are?t1→cχ01,?t1→bτ+and?t1→bμ+[12].The?rst one,a well-studied process,is a consequence of neutral?avour violation in SUSY and is suppressed by the small mismatch between quark and squark mass matrices.The latter ones are driven byλ′233andλ′333,and we?nd that they dominate for a light stop with mass≤150GeV so long asλ′233,λ′333lie in the range speci?ed above,in conformity with the SK data.
We focus our attention on single-muon and dimuon?nal states,together with jets and missing energy,arising from(light)stops pair-produced in p
We present some numerical estimates where the?ve degenerate squark?avours are as-sumed to have masses≈400GeV.The mass of the lighter stop is made to vary beween 80and150GeV,while the SU(2)gaugino mass M2is held?xed at150GeV.Uni?cation of the gaugino masses has been assumed.In addition,tanβ,the ratio of the two Higgs expectation values,has been?xed at3.Although we have not assumed any de?nite high scale SUSY breaking mechanism,it can be veri?ed that such combinations of parameters can indeed be realised in a supergravity(SUSY)framework.This is possible by using one’s freedom[13]with the trilinear soft SUSY breaking term A(while still preserving charge and colour invariance[14])and using the Higgsino parameterμas a phenomenological input[15], something that is just?ed if the Higgs mass parameters retain the freedom of di?ering from the‘universal’sfermion mass parameter(m0)at the grand uni?cation scale.
The above speci?ed set of parameters allows one to calculate the R-conserving stop decay width.For the R-parity violating two-body decays,we have used three sets of values forλ′233=λ′333,consistent with the expectation from the SK https://www.doczj.com/doc/f88759711.html,ing these,it is straightforward to calculate the branching ratios of the various stop decay modes.It is found that for the region of parameter space under investigation here,the branching ratio for R-parity violating decays ranges from75to99per cent,with a near-equal share between the bτand bμchannels.
A parton level Monte Carlo calculation has been performed for both single muon+ three jets+E T and dimuon+two jets+E T?nal states arising from stop pair-production at the Tevatron.In the former case,we have demanded that at least one jet be identi?ed as a b-induced one.Both the top-and stop-production cross-sections have been QCD corrected using a a so-called K-factor of1.4in case of top[16]and1.3[17]for the stop.For hadronic decays of the tau,we have considered only modes with one charged track,arising from τ±→π±ντ,ρ±ντ,a±1ντ.In order to calibrate our parton-level results,we have computed the numbers of the same types of expected signal events from top quark pair production. The numbers of both single-muon and dimuon events thus calculated in the latter case agree, within small errors,with the actual observations[18,19],so that our results may be treated
as reasonable estimates of how many stop-induced events can be contained in the top signal.
Since our main purpose is to see how stop signal can percolate into top signals for which detectors are already designed,both have been subjected to the same set of cuts,as speci?ed by the CDF top search strategy.In both types of?nal states of our interest,jets are de?ned using the cone algorithm as discussed in Ref.[18,19].Jets are counted in the analysis only if|η|jet<2whereηis the pseudorapidity[18,19].For single muon?nal state we require jets with E T>15GeV,at least one of which is identi?ed as a b-jet(with identi?cation e?ciency≈40%[18])while for dimuon?nal state two jets with E T>10GeV are required
√
[19].Two jets are merged if?R≤0.4,where?R=
stop-pairs.It is clear from?gure2that the dimuon data should de?nitely rule out the entire stop mass interval that is otherwise constrained assuming B(?t1→cχ01)?1.In fact, the limit can perhaps be pushed somewhat higher up in the R-parity violating case.For λ′233?λ′333=10?4,this limit should be around125GeV with the currently available data, while forλ′-values of5×10?4it touches about140GeV.
From the single muon signal too,stop masses upto about120?125GeV seem to be ruled out.We also want to emphasize that both this channel and the dimuon one can be used e?ectively in the context of Run II of the Tevatron to look for SUSY signals burried within the top data.A careful analysis of the dimuon versus dielectron data there,invigorated by the additional available luminosity,may lead to successful identi?cation of an excess in the former,thereby indicating R-parity violation of a kind that simultaneously explains the atmospheric neutrino puzzle.
For simplicity,we have con?ned ourselves in the above discussion to cases where the stop is kinematically forbidden to decay into a b quark and a chargino.Such a decay can be possible when M2and consequently the mass of lightest neutralino is smaller.However,in view of the fact that the chargino can subsequently decay into a lepton,the above mode can in e?ect strengthen the stop contribution.
The values of R-parity violating couplings which are as small as the ones under study here are unlikely to contribute to precision electroweak data[20]or to R-parity violating decays of the top quark[21]such as t?→b?l or t?→?bl even if they are kinematically allowed.However,with couplings several times larger in magnitude(with larger average squark mass,for example),some of these decays could lead to additional signals(?nal states of higher multiplicity)from the decays of the top,particularly at Run II of the Fermilab Tevatron.
Another signal,similar in nature to the ones discussed above,is one where both the stops decay into the bμchannel.In this case one shall see dimuons with two jets.Proper b-identifaction in the jets,together with e?ective measures to eliminate the Drell-Yan back-grounds,can establish such?nal states as rather e?ective ones for discovering a light stop
in an R-parity violating theory.
As has been mentioned at the beginning,the above discussion has assumed only trilinear R-parity violating interactions.The presence of the bilinear terms of the form L i H2in the superpotential(and the consequent vacuum expectation values for sneutrinos)can give rise to mixing between charged leptons and charginos[22],which can again lead to top-like signals of the same kinds from stop decays.A detailed analysis of the signals in such a case will soon be presented by us[23].
In conclusion,the?rst signals of R-parity violating SUSY observable in current and upcoming experiments can very well mimic those of the top quark.This is particularly true if the theory has to account for the neutrino masses and mixing suggested by experimental results on atmospheric muon neutrinos.We can use the already available single lepton+jets as well as dilepton data from the Fermilab Tevatron to constrain a large range of the lighter stop mass in such a scenario.In the upgraded version of the Tevatron,too,top quark signals will continue to be useful probes for such types of SUSY.
We thank S.Raychaudhuri and M.Guchait for technical help.
REFERENCES
[1]For reviews,see,e.g.,H.P.Nilles,Phys.Rep.110,1(1984);H.E.Haber and G.L.
Kane,Phys.Rep.117,75(1985);G.Kane(ed.),Perspectives on Supersymmetry(World Scienti?c).
[2]J.Ellis and S.Rudaz,Phys.Lett.B128,248(1983).
[3]K.Hikasa and M.Kobayashi,Phys.Rev.D36,724(1987);H.Baer et al.,Phys.Rev.
D44,725(1991);H.Baer,J.Sender and X.Tata,Phys.Rev.D50,4517(1994). [4]In addition,three-body decays of the stop can be of some signi?cance over a limited
region of the parameter sapce.For discussions see,e.g.,A.Bartl et al.,Z.Phys.C73, 469(1997);W.Porod and T.W¨o hrmann,Phys.Rev.D55,2907(1997);W.Porod, Phys.Rev.D59,095009(1999);A.Datta,M.Guchait and K.K.Jeong,Int.Jour.of Mod.Phys.A142239(1999).
[5]CDF Collaboration,F.Abe et al.,Phys.Rev.Lett.83,2133(1999);CDF Collaboration,
T.A?older et al.,hep-ex/9910049.
[6]V.Barger,G.Giudice and T.Han,Phys.Rev.D40,2987(1989);
[7]D.P.Roy,Phys.Lett.B283,270(1992);D.K.Ghosh,S.Raychaudhuri and K.Sridhar,
Phys.Lett.B396,177(1997);R.M.Godbole,P.Roy and X.Tata,Nucl.Phys.B 401,67(1993);D.Chowdhury and S.Raychaudhuri,Phys.Lett.B401,54(1997);
H.Dreiner,hep-ph/9707435,published in Perspective on Supersymmetry,ed.by G.L.
Kane;Report of the Group on R-parity Violation,R.Barbier et al.,hep-ph/9810232.
[8]SuperKamiokande Collaboration,Y.Fukuda et.al.,Phys.Rev.Lett.81,1562(1998).
[9]SOUDAN2Collaboration,W.W.M.Allison et al.,Phys.Lett.B449,137(1999).
[10]MACRO Collaboration,M.Ambrosio et al.,Phys.Lett.B434,451(1998).
[11]M.Drees,S.Pakvasa,X.Tata,and T.ter Veldhuis,Phys.Rev.D57,5335(1998);B.
Mukhopadhyaya,S.Roy,and F.Vissani,Phys.Lett.B443,191(1998).S.Rakshit,G.
Bhattarchyya,and A.Raychaudhuri,Phys.Rev.D59,091701(1999).
[12]H.Dreiner and R.J.N.Phillips,Nucl.Phys.B367,591(1991);F.de Campos et al.,
hep-ph/9903245;M.A.D′?az et al.,hep-ph/9908286;M.A.D′?az,hep-ph/9911274;W.
Porod,D.Restrepo and J.W.F.Valle,hep-ph/0001033.
[13]W.de Boer,R.Ehret and D.I.Kazakov,Z.Phys.C67,647(1995).
[14]J.A.Casas,A.Lleyda and C.Munoz,Nucl.Phys.B47,3(1996).
[15]C.Boehm,A.Djouadi and M.Drees,hep-ph/9911496.
[16]E.Berger and H.Contopanagos,Phys.Rev.D54,3085(1996);S.Catani,M.Mangano,
P.Nason and L.Trentadue,Phys.Lett.B378,329(1996).
[17]W.Beenakker et al.,Nucl.Phys.B515,3(1998).
[18]CDF Collaboration,F.Abe et al.,Phys.Rev.Lett.74,2626(1995);CDF Collaboration,
F.Abe et al.,Phys.Rev.Lett.80,2773(1998).
[19]CDF Collaboration,F.Abe et al.,Phys.Rev.Lett.80,2779(1998);CDF Collaboration,
F.Abe et al.,Phys.Rev.Lett.82,271(1999).
[20]J.Erler,J.Feng and N.Polonsky,Phys.Rev.Lett.78,3063(1997).
[21]K.Agashe and M.Graesser,Phys.Rev.D54,4445(1996);L.Navarro,W.Porod and
J.Valle,Phys.Lett.B459,615(1999).
[22]L.Hall and M.Suzuki,Nucl.Phys.B231,419(1984);R.Hemp?ing,Nucl.Phys.B
478,3(1996);H.P.Nilles and N.Polonsky,Nucl.Phys.B484,33(1997);S.Roy and
B.Mukhopadhyaya,Phys.Rev.D55,7020(1997);M.A.Garc′?a-Jare?n o,and J.W.F.
Valle,Nucl.Phys.B529,3(1998);M.A.D′?az,J.Ferrandis,J.C.Rom?a o,and J.W.F.
Valle,Phys.Lett.B453,263(1999);M.A.D′?az,E.Torrente-Lujan,J.W.F.Valle,Nucl.
Phys.B551,78(1999);E.J.Chun,S.K.Kang,C.W.Kim,and U.W.Lee,Nucl.Phys.
B544,89(1999);A.S.Joshipura and S.K.Vempati,Phys.Rev.D60,095009(1999);
Chao-Hsi Chang and Tai-Fu Feng,Eur.Phys.Jour.,C12,137(2000);A.Datta,B.
Mukhopadhyaya and S.Roy,Phys.Rev.D61,055006(2000).
[23]A.Datta and B.Mukhopadhyaya,in preparation.
FIGURES
FIG.1.Contributions to single muon+3jets+E T events from tˉt production for m t=175 GeV(solid line)and?t1?t?1production(followed by R-parity violating decays of?t1’s,dashed lines)
as a function of m?t
1at Tevatron with
√
FIG.2.Same as in Fig.1except for contributions to di-muon+di-jet+E T events.
如何写先进个人事迹 篇一：如何写先进事迹材料 如何写先进事迹材料 一般有两种情况：一是先进个人，如先进工作者、优秀党员、劳动模范等；一是先进集体或先进单位，如先进党支部、先进车间或科室，抗洪抢险先进集体等。无论是先进个人还是先进集体，他们的先进事迹，内容各不相同，因此要整理材料，不可能固定一个模式。一般来说，可大体从以下方面进行整理。 (1)要拟定恰当的标题。先进事迹材料的标题，有两部分内容必不可少，一是要写明先进个人姓名和先进集体的名称，使人一眼便看出是哪个人或哪个集体、哪个单位的先进事迹。二是要概括标明先进事迹的主要内容或材料的用途。例如《王鬃同志端正党风的先进事迹》、《关于评选张鬃同志为全国新长征突击手的材料》、《关于评选鬃处党支部为省直机关先进党支部的材料》等。 (2)正文。正文的开头，要写明先进个人的简要情况，包括：姓名、性别、年龄、工作单位、职务、是否党团员等。此外，还要写明有关单位准备授予他(她)什么荣誉称号，或给予哪种形式的奖励。对先进集体、先进单位，要根据其先进事迹的主要内容，寥寥数语即应写明，不须用更多的文字。 然后，要写先进人物或先进集体的主要事迹。这部分内容是全篇材料
的主体，要下功夫写好，关键是要写得既具体，又不繁琐；既概括，又不抽象；既生动形象，又很实在。总之，就是要写得很有说服力，让人一看便可得出够得上先进的结论。比如，写一位端正党风先进人物的事迹材料，就应当着重写这位同志在发扬党的优良传统和作风方面都有哪些突出的先进事迹，在同不正之风作斗争中有哪些突出的表现。又如，写一位搞改革的先进人物的事迹材料，就应当着力写这位同志是从哪些方面进行改革的，已经取得了哪些突出的成果，特别是改革前后的．经济效益或社会效益都有了哪些明显的变化。在写这些先进事迹时，无论是先进个人还是先进集体的，都应选取那些具有代表性的具体事实来说明。必要时还可运用一些数字，以增强先进事迹材料的说服力。 为了使先进事迹的内容眉目清晰、更加条理化，在文字表述上还可分成若干自然段来写，特别是对那些涉及较多方面的先进事迹材料，采取这种写法尤为必要。如果将各方面内容材料都混在一起，是不易写明的。在分段写时，最好在每段之前根据内容标出小标题，或以明确的观点加以概括，使标题或观点与内容浑然一体。 最后，是先进事迹材料的署名。一般说，整理先进个人和先进集体的材料，都是以本级组织或上级组织的名义；是代表组织意见的。因此，材料整理完后，应经有关领导同志审定，以相应一级组织正式署名上报。这类材料不宜以个人名义署名。 写作典型经验材料-般包括以下几部分： (1)标题。有多种写法，通常是把典型经验高度集中地概括出来，一
英语各种词性的用法 (2011-11-10 19:35:25) 转载▼ 标签： 杂谈 名词nouns分为专有名词(指人、地方、团体等特有的名称)普通名词(指人或东西或一个抽象的名称)用法，一般做主语，表语，动词宾语，介词宾语，状语，宾补。 冠词Art.本身没有意义，分为定冠词(表示名词为特定者)和不定冠词(用在单数名词前，表示一个)用法，用在名词前，帮助名词指明含义。 数词Num.表示数目的多少或顺序。用法，作主语，宾语，定语，表语，同位语。 代词Pronouns代替名词的，具有名词和形容词的作用。具体用法，第二次提到一些名词的时候，一般用代词代替。 形容词adjectives用来修饰名词，说明事物或人的性质或特征。用法，作定语，表语，宾补。副词adverbs修饰动词，形容词，副词，或整个句子。用法，作状语，定语，表语，宾补。动词verbs用来表示动作或状态，决定时态。用法，很广，一般作谓语。 介词prepositions一种虚词，不能单独在句子中作任何成分，需构成介词短语。介词短语用法，作定语，状语，表语，宾补。 主语Ｓ，是在句子中说明全局中心主体的部分。一般由名词、代词、不定式、或相当于名词的词(例如动名词)或短语来充当。它的位置一般在句首。 谓语Ｖ，是用来说明主语做什么、是什么、怎么样的。一般由简单动词或动词短语构成。位置在主语后面。 表语Ｐ是说明主语是什么、或者怎么样的。由名词、形容词、副词或介词短语、不定时式来构成的。位置在系动词后面。 宾语Ｏ，是动作行为的对象。由名词，代词，不定式或相当于名词的词、短语来担任。他和系动词一起说明主语做什么，在谓语之后。 宾补ＯＣ，就是宾语补足语。用来补充宾语不能完全表达完整的意思。 状语，用来修饰动词、副词、或形容词的。表示行为发生的时间、地点、方式、程度、目的等。由副词，介词短语，不定式，或相当于介词的词或短语来表示。位置在句末，或句首。定语，用来修饰名词或代词。形容词、代词、数词、名词、介词短语、不定式一般作定语。位置一般在动词后名词前。 注明，系动词包括ｂｅ动词，表示保持或变成某种状态的动词和感官动词。感官动词就是看、听、感觉等。表示保持或变成某种状态的动词有ｂｅｃｏｍｅ变得，ｋｅｅｐ保持，ｒｅｍａｉｎ保持，ｇｅｔ变得，ｐｒｏｖｅ证明，ｇｒｏｗ变得，ｔｕｒｎ变得，ｓｅｅｍ似乎，ａｐｐｅａｒ好像。 基本句型 1.S+V 2.S+V+O 3.S+V+P 4.S+V+O+OC 5.S+V+IO间接宾语+DO直接宾语
How to manage time Time treats everyone fairly that we all have 24 hours per day. Some of us are capable to make good use of time while some find it hard to do so. Knowing how to manage them is essential in our life. Take myself as an example. When I was still a senior high student, I was fully occupied with my studies. Therefore, I hardly had spare time to have fun or develop my hobbies. But things were changed after I entered university. I got more free time than ever before. But ironically, I found it difficult to adjust this kind of brand-new school life and there was no such thing called time management on my mind. It was not until the second year that I realized I had wasted my whole year doing nothing. I could have taken up a Spanish course. I could have read ten books about the stories of successful people. I could have applied for a part-time job to earn some working experiences. B ut I didn’t spend my time on any of them. I felt guilty whenever I looked back to the moments that I just sat around doing nothing. It’s said that better late than never. At least I had the consciousness that I should stop wasting my time. Making up my mind is the first step for me to learn to manage my time. Next, I wrote a timetable, setting some targets that I had to finish each day. For instance, on Monday, I must read two pieces of news and review all the lessons that I have learnt on that day. By the way, the daily plan that I made was flexible. If there’s something unexpected that I had to finish first, I would reduce the time for resting or delay my target to the next day. Also, I would try to achieve those targets ahead of time that I planed so that I could reserve some more time to relax or do something out of my plan. At the beginning, it’s kind of difficult to s tick to the plan. But as time went by, having a plan for time in advance became a part of my life. At the same time, I gradually became a well-organized person. Now I’ve grasped the time management skill and I’m able to use my time efficiently.
英语演讲稿：未来的工作 这篇《英语演讲稿范文：未来的工作》，是特地，希望对大家有所帮助！ 热门演讲推荐：竞聘演讲稿 | 国旗下演讲稿 | 英语演讲稿 | 师德师风演讲稿 | 年会主持词 | 领导致辞 everybody good afternoon:. first of all thank the teacher gave me a story in my own future ideal job. everyone has a dream job. my dream is to bee a boss, own a pany. in order to achieve my dreams, i need to find a good job, to accumulate some experience and wealth, it is the necessary things of course, in the school good achievement and rich knowledge is also very important. good achievement and rich experience can let me work to make the right choice, have more opportunities and achievements. at the same time, munication is very important, because it determines whether my pany has a good future development. so i need to exercise their municative ability. i need to use all of the free time to learn
小学生个人读书事迹简介怎么写800字 书,是人类进步的阶梯,苏联作家高尔基的一句话道出了书的重要。书可谓是众多名人的“宠儿”。历来,名人说出关于书的名言数不胜数。今天小编在这给大家整理了小学生个人读书事迹,接下来随着小编一起来看看吧! 小学生个人读书事迹1 “万般皆下品,惟有读书高”、“书中自有颜如玉,书中自有黄金屋”,古往今来,读书的好处为人们所重视,有人“学而优则仕”,有人“满腹经纶”走上“传道授业解惑也”的道路……但是,从长远的角度看,笔者认为读书的好处在于增加了我们做事的成功率,改善了生活的质量。 三国时期的大将吕蒙,行伍出身,不重视文化的学习,行文时,常常要他人捉刀。经过主君孙权的劝导,吕蒙懂得了读书的重要性,从此手不释卷,成为了一代儒将,连东吴的智囊鲁肃都对他“刮目相待”。后来的事实证明,荆州之战的胜利,擒获“武圣”关羽,离不开吕蒙的“运筹帷幄,决胜千里”,而他的韬略离不开平时的读书。由此可见,一个人行事的成功率高低,与他的对读书,对知识的重视程度是密切相关的。 的物理学家牛顿曾近说过,“如果我比别人看得更远,那是因为我站在巨人的肩上”,鲜花和掌声面前,一代伟人没有迷失方向,自始至终对读书保持着热枕。牛顿的话语告诉我们,渊博的知识能让我们站在更高、更理性的角度来看问题,从而少犯错误,少走弯路。
读书的好处是显而易见的,但是,在社会发展日新月异的今天,依然不乏对读书,对知识缺乏认知的人,《今日说法》中我们反复看到农民工没有和用人单位签订劳动合同,最终讨薪无果;屠户不知道往牛肉里掺“巴西疯牛肉”是犯法的;某父母坚持“棍棒底下出孝子”,结果伤害了孩子的身心,也将自己送进了班房……对书本,对知识的零解读让他们付出了惨痛的代价,当他们奔波在讨薪的路上,当他们面对高墙电网时,幸福,从何谈起?高质量的生活,从何谈起? 读书,让我们体会到“锄禾日当午,汗滴禾下土”的艰辛;读书,让我们感知到“四海无闲田,农夫犹饿死”的无奈;读书,让我们感悟到“为报倾城随太守,西北望射天狼”的豪情壮志。 读书的好处在于提高了生活的质量,它填补了我们人生中的空白,让我们不至于在大好的年华里无所事事,从书本中,我们学会提炼出有用的信息,汲取成长所需的营养。所以,我们要认真读书,充分认识到读书对改善生活的重要意义,只有这样,才是一种负责任的生活态度。 小学生个人读书事迹2 所谓读一本好书就是交一个良师益友,但我认为读一本好书就是一次大冒险,大探究。一次体会书的过程,真的很有意思,咯咯的笑声,总是从书香里散发;沉思的目光也总是从书本里透露。是书给了我启示,是书填补了我无聊的夜空,也是书带我遨游整个古今中外。所以人活着就不能没有书,只要爱书你就是一个爱生活的人,只要爱书你就是一个大写的人,只要爱书你就是一个懂得珍惜与否的人。可真所谓
英语词性的分类及用法 一、词性的分类 词类又叫词性，英语单词根据其在句子中的功用，可以分成十个大类。 1 名词noun n. student 学生 2 代词pronoun pron. you 你 3 形容词adjective adj. happy 高兴的 4 副词adverb adv. quickly 迅速地 5 动词verb v. cut 砍、割 6 数词numeral num. three 三 7 冠词article art. a 一个 8 介词preposition prep. at 在... 9 连词conjunction conj. and 和 10 感叹词interjection interj. oh 哦 前六类叫实词，后四类叫虚词。 二、名词 名词概论 名词复数的规则变化 其它名词复数的规则变化 1) 以y结尾的专有名词，或元音字母+y 结尾的名词变复数时，直接加s变复数：如：two Marys the Henrys monkey---monkeys holiday---holidays 2) 以o 结尾的名词，变复数时： a. 加s，如：photo---photos piano---pianos radio---radios zoo---zoos； b. 加es，如：potato—potatoes tomato—tomatoes 3) 以f或fe 结尾的名词变复数时： a. 加s，如：belief---beliefs roof---roofs safe---safes gulf---gulfs； b. 去f, fe 加-ves，如：half---halves
关于坚持的英语演讲稿 Results are not important, but they can persist for many years as a commemoration of. Many years ago, as a result of habits and overeating formed one of obesity, as well as indicators of overall physical disorders, so that affects my work and life. In friends to encourage and supervise, the participated in the team Now considered to have been more than three years, neither the fine rain, regardless of winter heat, a day out with 5:00 time. The beginning, have been discouraged, suffering, and disappointment, but in the end of the urging of friends, to re-get up, stand on the playground. 成绩并不重要，但可以作为坚持多年晨跑的一个纪念。多年前，由于庸懒习惯和暴饮暴食，形成了一身的肥胖，以及体检指标的全盘失常，以致于影响到了我的工作和生活。在好友的鼓励和督促下，参加了晨跑队伍。现在算来，已经三年多了，无论天晴下雨，不管寒冬酷暑，每天五点准时起来出门晨跑。开始时，也曾气馁过、痛苦过、失望过，但最后都在好友们的催促下，重新爬起来，站到了操场上。 In fact, I did not build big, nor strong muscles, not a sport-born people. Over the past few years to adhere to it, because I have a team behind, the strength of a strongteam here, very grateful to our team, for a long time, we encourage each other, and with sweat, enjoying common health happy. For example, Friends of the several run in order to maintain order and unable to attend the 10，000 meters race, and they are always concerned about the brothers and promptly inform the place and time, gives us confidence and courage. At the same time, also came on their own inner desire and pursuit for a good health, who wrote many of their own log in order to refuel for their own, and inspiring. 其实我没有高大身材，也没健壮肌肉，天生不属于运动型的人。几年来能够坚持下来，因为我的背后有一个团队，有着强大团队的力量，在这里，非常感谢我们的晨跑队，长期以来，我们相互鼓励着，一起流汗，共同享受着健康带来的快
英语中各种词性的意义及用法 1、名词，Nouns (n.) 表示人或事物的名称的词，按意义分类 ①专有名词 表示具体的人，事物，地点，团体或机构的专有名称(第一个字母要大写)。例：China(中国)、Asia(亚洲)、the People’s Republic Of China(中华人民共和国)。 专有名词如果是含有名词短语，则必须使用定冠词the。如：the Great Wall(长城)。 姓氏名如果采用复数形式，则表示该姓氏一家人(复数含义)。如：the Greens(格林一家人)。 ②普通名词 表示某些人，某类事物，某种物质或抽象概念的名称。如： box, pen,tree,apple按是否可数分类 名词又可分为可数名词(Countable Nouns)和不可数名词(Uncountable Nouns) ①不可数名词 不可数名词是指不能以数目来计算，不可以分成个体的概念、状态、品质、感情或表 示物质材料的东西；它一般没有复数形式，只有单数形式，它的前面不能用不定冠词 a / an。抽象名词，物质名词和专有名词一般是不可数名词。 ②可数名词 可数名词是指能以数目来计算，可以分成个体的人或东西，因此它有复数形式。 2、代词，Pronouns (pron.)代替名词、数词、形容词的词，大多数代词具有名词和形 容词的功能。英语中的代词，按其意义、特征及在句中的作用分为：人称代词、物主代 词、指示代词、反身代词、相互代词、疑问代词、关系代词、连接代词和不定代词九种。 如：We, this, them, myself 3、动词，Verb (v.) 表示动作或状态的词，如：Jump,sing,visit，它又分为及物动 词和不及物动词两大类： ①及物动词：字典里词后标有transitive verb（vt.）的就是及物动词。及物动词后 一般必须跟有动作的对象（即宾语）。必须加宾语意思才完整的动词，就是及物动词。 ②不及物动词：不及物动词是不需要受词的动词。字典里词后标有intransitive verb （vi.）的就是不及物动词。不及物动词后不能直接跟有动作的对象（即宾语）。若要跟宾 语，必须先在其后添加上某个介词，如to,of ,at等后方可跟上宾语。 ③系动词：联系动词或称不完全不及物动词，虽有意义，但不完全，需要加名词、形 容词、代名词等作主词补语以补足其意义。常和形容词连用构成系表结构的连系动词有： look （看起来，看上去）， feel （感觉）， taste （尝起来）， smell （闻起来），get （变得），turn（变），become（成为，变得），sound （听起来）等。 例如： The weather gets warmer and the trees turn green in spring. 春天天气 变暖和了，树变绿了。 The flowers smell sweet. 这些花闻起来很香。 The soup taste nice. 这汤尝上去很好吃。
1.How to build a business that lasts100years 0:11Imagine that you are a product designer.And you've designed a product,a new type of product,called the human immune system.You're pitching this product to a skeptical,strictly no-nonsense manager.Let's call him Bob.I think we all know at least one Bob,right?How would that go? 0:34Bob,I've got this incredible idea for a completely new type of personal health product.It's called the human immune system.I can see from your face that you're having some problems with this.Don't worry.I know it's very complicated.I don't want to take you through the gory details,I just want to tell you about some of the amazing features of this product.First of all,it cleverly uses redundancy by having millions of copies of each component--leukocytes,white blood cells--before they're actually needed,to create a massive buffer against the unexpected.And it cleverly leverages diversity by having not just leukocytes but B cells,T cells,natural killer cells,antibodies.The components don't really matter.The point is that together,this diversity of different approaches can cope with more or less anything that evolution has been able to throw up.And the design is completely modular.You have the surface barrier of the human skin,you have the very rapidly reacting innate immune system and then you have the highly targeted adaptive immune system.The point is,that if one system fails,another can take over,creating a virtually foolproof system. 1:54I can see I'm losing you,Bob,but stay with me,because here is the really killer feature.The product is completely adaptive.It's able to actually develop targeted antibodies to threats that it's never even met before.It actually also does this with incredible prudence,detecting and reacting to every tiny threat,and furthermore, remembering every previous threat,in case they are ever encountered again.What I'm pitching you today is actually not a stand-alone product.The product is embedded in the larger system of the human body,and it works in complete harmony with that system,to create this unprecedented level of biological protection.So Bob,just tell me honestly,what do you think of my product? 2:47And Bob may say something like,I sincerely appreciate the effort and passion that have gone into your presentation,blah blah blah-- 2:56(Laughter) 2:58But honestly,it's total nonsense.You seem to be saying that the key selling points of your product are that it is inefficient and complex.Didn't they teach you 80-20?And furthermore,you're saying that this product is siloed.It overreacts, makes things up as it goes along and is actually designed for somebody else's benefit. I'm sorry to break it to you,but I don't think this one is a winner.
关于工作的优秀英语演讲稿 Different people have various ambitions. Some want to be engineers or doctors in the future. Some want to be scientists or businessmen. Still some wish to be teachers or lawers when they grow up in the days to come. Unlike other people, I prefer to be a farmer. However, it is not easy to be a farmer for Iwill be looked upon by others. Anyway,what I am trying to do is to make great contributions to agriculture. It is well known that farming is the basic of the country. Above all, farming is not only a challenge but also a good opportunity for the young. We can also make a big profit by growing vegetables and food in a scientific way. Besides we can apply what we have learned in school to farming. Thus our countryside will become more and more properous. I believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. All the working position can provide him with a good chance to become a talent. 1 ————来源网络整理，仅供供参考
个人先进事迹简介 01 在思想政治方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.利用课余时间和党课机会认真学习政治理论,积极向党组织靠拢. 在学习上,xxxx同学认为只有把学习成绩确实提高才能为将来的实践打下扎实的基础,成为社会有用人才.学习努力、成绩优良. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意识和良好的心理素质和从容、坦诚、乐观、快乐的生活态度,乐于帮助身边的同学,受到师生的好评. 02 xxx同学认真学习政治理论,积极上进,在校期间获得原院级三好生,和校级三好生,优秀团员称号,并获得三等奖学金. 在学习上遇到不理解的地方也常常向老师请教,还勇于向老师提出质疑.在完成自己学业的同时,能主动帮助其他同学解决学习上的难题,和其他同学共同探讨,共同进步. 在社会实践方面,xxxx同学参与了中国儿童文学精品“悦”读书系,插画绘制工作,xxxx同学在班中担任宣传委员,工作积极主动,认真负责,有较强的组织能力.能够在老师、班主任的指导下独立完成学院、班级布置的各项工作. 03 xxx同学在政治思想方面积极进取,严格要求自己.在学习方面刻苦努力,不断钻研,学习成绩优异,连续两年荣获国家励志奖学金；作
为一名学生干部,她总是充满激情的迎接并完成各项工作,荣获优秀团干部称号.在社会实践和志愿者活动中起到模范带头作用. 04 xxxx同学在思想方面,积极要求进步,为人诚实,尊敬师长.严格 要求自己.在大一期间就积极参加了党课初、高级班的学习,拥护中国共产党的领导,并积极向党组织靠拢. 在工作上,作为班中的学习委员,对待工作兢兢业业、尽职尽责 的完成班集体的各项工作任务.并在班级和系里能够起骨干带头作用.热心为同学服务,工作责任心强. 在学习上,学习目的明确、态度端正、刻苦努力,连续两学年在 班级的综合测评排名中获得第1.并荣获院级二等奖学金、三好生、优秀班干部、优秀团员等奖项. 在社会实践方面,积极参加学校和班级组织的各项政治活动,并 在志愿者活动中起到模范带头作用.积极锻炼身体.能够处理好学习与工作的关系,乐于助人,团结班中每一位同学,谦虚好学,受到师生的好评. 05 在思想方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.作为一名共产党员时刻起到积极的带头作用,利用课余时间和党课机会认真学习政治理论. 在工作上,作为班中的团支部书记,xxxx同学积极策划组织各类 团活动,具有良好的组织能力. 在学习上,xxxx同学学习努力、成绩优良、并热心帮助在学习上有困难的同学,连续两年获得二等奖学金. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意 识和良好的心理素质.
尊敬的领导，老师，亲爱的同学们， 大家好！我是5班的梁浩东。今天早上我坐车来学校的路上，我仔细观察了路上形形色色的人，有开着小车衣着精致的叔叔阿姨，有市场带着倦容的卖各种早点的阿姨，还有偶尔穿梭于人群中衣衫褴褛的乞丐。于是我问自己，十几年后我会成为怎样的自己，想成为社会成功人士还是碌碌无为的人呢，答案肯定是前者。那么十几年后我怎样才能如愿以偿呢，成为一个受人尊重，有价值的人呢？正如我今天演讲的题目是：自主管理。 大家都知道爱玩是我们孩子的天性，学习也是我们的责任和义务。要怎样处理好这些矛盾，提高自主管理呢？ 首先，我们要有小主人翁思想，自己做自己的主人，要认识到我们学习，生活这一切都是我们自己走自己的人生路，并不是为了报答父母，更不是为了敷衍老师。 我认为自主管理又可以理解为自我管理，在学习和生活中无处不在，比如通过老师，小组长来管理约束行为和同学们对自身行为的管理都属于自我管理。比如我们到一个旅游景点，看到一块大石头，有的同学特别兴奋，会想在上面刻上：某某某到此一游话。这时你就需要自我管理，你需要提醒自己，这样做会破坏景点，而且是一种素质低下的表现。你设想一下，如果别人家小孩去你家墙上乱涂乱画，你是何种感受。同样我们把自主管理放到学习上，在我们想偷懒，想逃避，想放弃的时候，我们可以通过自主管理来避免这些，通过他人或者自己的力量来完成。例如我会制定作息时间计划表，里面包括学习，运动，玩耍等内容的完成时间。那些学校学习尖子，他们学习好是智商高于我们吗，其实不然，在我所了解的哪些优秀的学霸传授经验里，就提到要能够自我管理，规范好学习时间的分分秒秒，只有辛勤的付出，才能取得优异成绩。 在现实生活中，无数成功人士告诉我们自主管理的重要性。十几年后我想成为一位优秀的，为国家多做贡献的人。亲爱的同学们，你们们？让我们从现在开始重视和执行自主管理，十几年后成为那个你想成为的人。 谢谢大家！
关于工作的英语演讲稿 【篇一：关于工作的英语演讲稿】 关于工作的英语演讲稿 different people have various ambitions. some want to be engineers or doctors in the future. some want to be scientists or businessmen. still some wish to be teachers or lawers when they grow up in the days to come. unlike other people, i prefer to be a farmer. however, it is not easy to be a farmer for iwill be looked upon by others. anyway,what i am trying to do is to make great contributions to agriculture. it is well known that farming is the basic of the country. above all, farming is not only a challenge but also a good opportunity for the young. we can also make a big profit by growing vegetables and food in a scientific way. besides we can apply what we have learned in school to farming. thus our countryside will become more and more properous. i believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. all the working position can provide him with a good chance to become a talent. 【篇二：关于责任感的英语演讲稿】 im grateful that ive been given this opportunity to stand here as a spokesman. facing all of you on the stage, i have the exciting feeling of participating in this speech competition. the topic today is what we cannot afford to lose. if you ask me this question, i must tell you that i think the answer is a word---- responsibility. in my elementary years, there was a little girl in the class who worked very hard, however she could never do satisfactorily in her lessons. the teacher asked me to help her, and it was obvious that she expected a lot from me. but as a young boy, i was so restless and thoughtless, i always tried to get more time to play and enjoy myself. so she was always slighted over by me. one day before the final exam, she came up to me and said, could you please explain this to me? i can not understand it. i
英语词性的分类及用法 词类又叫词性，英语单词根据其在句子中的功用，可以分成十个大类。 1 名词noun n. student 学生 2 代词pronoun pron. you 你 3 形容词adjective adj. happy 高兴的 4 副词adverb adv. quickly 迅速地 5 动词verb v. cut 砍、割 6 数词numeral num. three 三 7 冠词article art. a 一个8 介词preposition prep. at 在... 9 连词conjunction conj. and 和10 感叹词interjection interj. oh 哦 前六类叫实词，后四类叫虚词。 名词(表示人或物名称的词) ?名词可以分为专有名词和普通名词. ?专有名词是某个（些）人，地方，机构等专有的名称，如Beijing，China, the United States,等。 ?普通名词是一类人或东西或是一个抽象概念的名词，如：book，sadness等。(普 通名词包括可数名词和不可数名词) ?普通名词又可分为下面四类： 1）个体名词：表示某类人或东西中的个体，如：gun 2）集体名词：表示若干个个体组成的集合体，如:family ?(以上两类属于可数名词) 3）物质名词：表示无法分为个体的实物，如:air 4）抽象名词：表示动作、状态、品质、感情等抽象概念，如：work ?(以上两类属于不可数名词) 代词(代替名词的词) ?代词可以分为下列九类： ? 1. 人称代词：They are my school mates. ? 2. 物主代词：Our friends have great concern for each other. ? 3. 反身代词：Take good care of yourselves. ? 4. 相互代词：We should help each other. ? 5. 指示代词：Who are these people? ? 6. 疑问代词：What are you doing? ?7. 关系代词：She married Tony Harper, who is a student too. ?8. 连接代词：Do you know who did it? ?9. 不定代词：Do you know anything about it? ? ?代词是非常活跃的词，特别是不定代词，比较复杂，我们要熟练掌握。 形容词(修饰名词等，说明事物或人的性质或特征的词) ?形容词可分成性质形容词和叙述形容词两类，其位置不一定都放在名词前面。 1) 直接说明事物的性质或特征的形容词是性质形容词，它有级的变化，可以用程度 副词修饰，在句中可作定语、表语和补语。例如：hot ,good ,wonderful等. 2) 叙述形容词只能作表语，所以又称为表语形容词。这类形容词没有级的变化，也 不可用程度副词修饰。大多数以a开头的形容词都属于这一类。例如：afraid, alone 等.