Comparison of Deep Inelastic Electron-Photon Scattering Data with the Herwig and Phojet Mon

a r X i v :h e p -e x /0010041v 1 17 O c t 2000

EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH

CERN-EP-2000-109

July 3,2000

Comparison of Deep Inelastic Electron-Photon Scattering Data with the Herwig and Phojet Monte

Carlo Models

ALEPH,L3and OPAL Collaborations 1.

The LEP Working Group for Two-Photon Physics 2

Abstract

Deep inelastic electron-photon scattering is studied in the Q 2range from 1.2to 30GeV 2using the LEP1data taken with the ALEPH,L3and OPAL detectors at centre-of-mass energies close to the mass of the Z boson.Distributions of the measured hadronic ?nal state are corrected to the hadron level and compared to the predictions of the HERWIG and PHOJET Monte Carlo models.For large regions in most of the distributions stud-ied the results of the di?erent experiments agree with one another.However,signi?cant di?erences are found between the data and the models.Therefore the combined LEP data serve as an important input to improve on the Monte Carlo models.

Submitted to European Physical Journal C

1Introduction

The measurement of the hadronic structure function Fγ2crucially depends on the ac-curate description of the hadronic?nal state by Monte Carlo models.The available models do not properly account for all features observed in the data,and therefore, at present,the accuracy of the measurement of Fγ2is mainly limited by the imperfect description of the hadronic?nal state by the Monte Carlo models.In previous analyses of the individual LEP experiments[1–4],it had been shown that there are discrepancies in several distributions of the hadronic?nal state between the various QCD models and the data.It has also be seen that the data are precise enough to further constrain the models.The purpose of this paper is to combine the ALEPH,L3and OPAL data to establish a consistent and signi?cant measurement,which can be used to optimise the models.

In this paper the reaction e+e?→e+e?γ?γ→e+e?hadrons,proceeding via the exchange of two photons,is studied in the single tag con?guration,where one scattered electron3is detected.The di?erential cross-section for the deep inelastic electron-photon scattering reaction,e(k)γ(p)→e(k′)γ(p)γ?(q)→e X,where the terms in brackets denote the four-momentum vectors of the particles,is proportional to Fγ2(x,Q2)[5].Here Q2=?q2=?(k?k′)2and x=Q2/2p·q.Experimentally,in the single tag con?guration,the value of x is obtained using

Q2

x=

of the tagged electron,E t,out,

?the number of charged particles,N trk,

?the transverse momenta of charged particles with respect to the beam axis,p t,trk,?and the hadronic energy?ow,1/N·d E/dη,as a function of the pseudorapidityη=?ln(tan(θ/2))with respect to the beam axis,where N denotes the number of events. The complete de?nition of how these variables are calculated is given in Section3.

For W res,E t,out and N trk the result is a di?erential event cross-section,which means, the distributions have one entry per event,whereas for p t,trk the distribution is a one-particle inclusive cross-section.The hadronic energy?ow is shown as an average energy ?ow per event, E/N,where the sum runs over all objects and over all events in a given bin of pseudorapidity.

The analysis presented here is based on data of the individual experiments taken at centre-of-mass energies close to the mass of the Z boson.The approximate ranges in Q2 and x of the di?erent experiments used in this analysis,and the integrated luminosities are listed in Table1.The Q2ranges are calculated from the requirements on the energy and angle of the deeply inelastically scattered electron,and the x ranges are derived from Eq.1,using the range in Q2and the approximate reach in hadronic invariant mass of3

L3

Q2range 1.2–6.3GeV2

0.001–0.770.001–0.77

L int140pb?1

The HERWIG version used for event simulation is HERWIG5.9+k t,where the label k t denotes that the k t distribution has been altered from the program default.This change is made to improve the agreement for the high-Q2region between the ALEPH and OPAL data and the original HERWIG prediction,where the original program is denoted as HERWIG default.The default Gaussian behaviour is replaced by a power-law function of the form d k2t/(k2t+k20)[9]with k0=0.66GeV.The change is motivated by the observation made in photoproduction studies at HERA[10],where the power-law function gave a better description of the data.This is a good example of how information from two di?erent,but related reactions can be used to improve on a general purpose Monte Carlo program.It is interesting to note that the same value of k0is chosen to describe both,photoproduction and deep inelastic electron-photon scattering events.The upper limit of k2t in HERWIG+k t is?xed at k2t,max=25GeV2, which is almost the upper limit of Q2for the Q2region studied,as shown in Table1.

Based on the distributions presented in Section5the?xed cut-o?has been replaced by dynamically adjusting the upper limit on k t on an event by event basis[11].In this scheme the maximum transverse momentum k2t,max is set to the hardest virtuality scale in the event,which is of order Q2.The distributions produced with this procedure are denoted as HERWIG+k t(dyn).

The PHOJET Monte Carlo is based on the Dual Parton Model[12].It is designed for hadron-hadron,photon-hadron and photon-photon collisions,where originally only real or quasi-real photons were considered.It has recently been extended to simulate the deep inelastic electron-photon scattering case,where one of the photons is highly virtual.For the case of deep inelastic scattering the program is not based on the DIS formula using Fγ2,but theγ?γcross-section is calculated from theγγcross-section by extrapolating in Q2on the basis of the Generalised Vector Dominance model.The events are generated from soft and hard partonic processes,where a cut-o?of2.5GeV on the transverse momentum of the scattered partons in the photon-photon centre-of-mass system is used to separate the two classes of events.The hard processes are sub-divided into direct processes,where the photon as a whole takes part in the hard interactions,and resolved processes.In resolved processes either one or both photons ?uctuate into a hadronic state,and a quark or gluon of one hadronic state interacts either with the other photon,or with a quark or gluon of the second hadronic state. Also virtual photons can interact as resolved states,however,the parton distribution functions of the photons are suppressed as a function of the photon virtualities.The sum of the processes is matched to the deep inelastic scattering cross-section.Initial state parton showers are simulated with a backward evolution algorithm using the transverse momentum as evolution scale.Final state parton showers are generated with the Lund code JETSET[13].Both satisfy angular ordering implied by coherence e?ects. The hadronisation is based on the Lund string model as implemented in JETSET.

3Experimental Method

Large data sets are generated with the PHOJET and HERWIG+k t programs respec-√

tively,for

luminosities for the PHOJET and HERWIG+k t samples are831pb?1and683pb?1 respectively4.

The de?nitions of the phase space and observables include cuts at generator level both on the events and on the particles within the events.The cuts are chosen such that the individual detectors have good acceptance and therefore detector related un-certainties are expected to be small.To select the events at this stage,the following cuts are applied to the generated hadron level quantities:

1.The energy of the deeply inelastically scattered electron has to be larger than

35GeV.

2.The polar angleθtag of the deeply inelastically scattered electron with respect

to either beam direction has to be in the ranges27?55mrad(low-Q2region) or60?120mrad(high-Q2region).The two ranges in scattering angles studied correspond to Q2ranges of about1.2

3.The events are required to contain no electron with energy of more than35GeV

and polar angle above25mrad with respect to the beam direction in the hemi-sphere opposite to the one containing the deeply inelastically scattered electron.

4.The number of charged particles N trk,calculated by summing over all charged

particles which have a transverse momentum p t with respect to the beam axis of more than200MeV and polar angles,θ,with respect to the beam axis,in the range20<θ<160?,has to be greater than or equal to3.The values chosen closely resemble the acceptance of the tracking detectors.

5.The invariant mass W res,calculated by summing over all charged and neutral

particles ful?lling p t>200MeV and20<θ<160?,corresponding to|η|<1.735, has to be larger than3GeV.

This set of particles and cuts de?nes the hadron level and the data are corrected to this level.The hadron level predictions of W res and E t,out are calculated from the charged and neutral particles de?ned above,and the distributions of N trk and p t,trk from the charged particles alone.The only exception is the hadronic energy ?ow.For the hadronic energy?ow,the same event selection has been applied,but all particles are included in the distribution without applying a cut on transverse momentum.Figure1shows the di?erential cross-section dσ/d Q2within the cuts listed above and corrected for detector e?ects.The vertical line roughly separates the low-Q2and high-Q2regions.Since Q2depends on the energy and angle of the deeply inelastically scattered electron there is a slight overlap in Q2,but due to the cut on θtag the two samples are statistically independent.In the kinematic region studied the cross-section prediction of HERWIG+k t is about40%higher than the prediction based on PHOJET as shown in Figure1.

To study the experimentally observable distributions at the detector level samples of 60k HERWIG+k t and120k PHOJET events,which are statistically independent from the samples mentioned above,are passed through the detector simulation programs of the ALEPH,L3and OPAL collaborations,ensuring that all experiments use identical events.The objects reconstructed after the detector simulation are energy clusters, measured in the electromagnetic and hadronic calorimeters,and tracks,measured in

the tracking devices.Identical event selection cuts at the detector level are applied by all experiments,closely re?ecting the cuts applied at the hadron level as described above:

1.A cluster of at least35GeV is required in one of the small angle electromagnetic

luminosity monitors.

2.The polar angle with respect to either beam direction of the cluster has to be in

the range from27?55mrad or60?120mrad.

3.The most energetic cluster in the hemisphere opposite to the tagged electron has

to have energy less than35GeV.

4.At least3tracks,ful?lling a set of quality criteria,are required to be observed in

the tracking devices with20?<θ<160?,and with p t,trk of at least200MeV.

5.The invariant mass,W res,calculated from all tracks and clusters with p t>

200MeV and20<θ<160?is required to be greater than3GeV.

These objects de?ne the detector level.They are used for the W res,E t,out,N trk and p t,trk distributions.The only exception is the energy?ow1/N·d E/dη,where again no cut on the transverse momentum has been applied.

With this strategy it is ensured that the hadron level distributions,which are ob-tained from the large size samples without detector simulation,and the detector level distributions,which are obtained from the samples of smaller size with a detailed de-tector simulation for each individual experiment,are statistically independent.Both samples are used in the correction procedure applied to the data described in the next section.

4Corrections for Detector E?ects

Before a measured quantity can be compared to theoretical predictions or to the results of other measurements it must?rst be corrected for various detector related e?ects, such as geometrical acceptance,detector ine?ciency and resolution,decays,particle interactions with the material of the detector and the e?ects of the event and track selections.Figure2shows the energy?ow,1/N·d E/dη,predicted by the HERWIG+k t model at the hadron level as well as at the detector level,for the three detectors.The events are entered in the?gure such that the deeply inelastically scattered electron is always at negative rapidities,but not shown.Also shown in the?gure is the coverage inηof the various sub-detectors used in this analysis.A detailed description of the ALEPH,L3and OPAL detectors can be found in[16],[17],and[18]respectively.The central region of all the detectors with?1.735<η<1.735is covered by tracking and calorimetry.The forwardη>1.735,and backwardη

For the analysis presented here,the correction of the data to the hadron level is

done with multiplicative factors,f,relating the measured value X meas

data of a quantity X,

such as a bin content,to the corrected value,X corr

data

using the relation:

For distributions,the correction factors are computed bin by bin,e.g.for the energy ?ow,f is the ratio of the hadron level(lightly shaded)and the detector level(darkly shaded)distributions shown in Figure2.In this way of correcting the data the as-sumption is made that within the restricted angular range there is little smearing of the variables between bins,hence a simple correction factor is justi?ed,and therefore no attempt to use an unfolding procedure has been made.The Monte Carlo was used to verify the accuracy of this assumption.Application of this correction results in measurements corrected to a well-de?ned kinematical region and particle composition, as de?ned in Section3.

The correction factors for the energy?ow in the low-Q2region are shown in Fig-ure3.The correction factors are near one in the central region of pseudorapidity where identical cuts have been applied and they are similar for the three experiments.How-ever,there is a much larger spread in the region of larger pseudorapidityη>1.735, where the experiments have di?erent sub-detectors,di?erent angular coverage,and apply di?erent cuts.For ALEPH and OPAL the clusters in the forward detectors are required to have an energy of at least1GeV,while for L3this requirement is at least 4GeV.This leads to larger correction factors for L3in that region.In addition,for L3,the clusters measured in the forward detectors on the side of the tagged electron, i.e.atη

The correction factors in the low-Q2region for the other chosen variables and for the ALEPH,L3and OPAL experiments using the HERWIG+k t and PHOJET mod-els,are shown in Figures4and5.The quoted errors of the correction factors are the combined statistical uncertainties of the generated hadron level and the simu-lated detector level quantities.While the di?erences between the correction factors obtained from HERWIG+k t and PHOJET are very small for the energy?ow,they can vary signi?cantly for other variables.For example,in the case of OPAL,for W res the HERWIG+k t correction factors are on average about20%higher than the factors obtained with PHOJET.The correction factors for the low-Q2and high-Q2regions typically di?er by less than10%.

5Corrected Data Comparisons

The discussion of the comparison is subdivided into three parts.First the corrected data from the individual experiments are compared to each other and to the Monte Carlo models.In this comparison only statistical errors are used and no attempt has been made to obtain estimates of systematic errors for the individual experiments. Based on the above comparison a modi?ed version of the HERWIG+k model has been

Monte Carlo models.In the combination of the data the spread of the experiments is used as an estimate of the systematic uncertainty of the measured distributions.The

numerical results are listed in Tables2–12and can be obtained in electronic form[19].

5.1Data from individual experiments

The Figures6–13show the corrected di?erential cross-sections,calculated in the kine-matical range described in Section3,for the data compared with the HERWIG+k t and PHOJET predictions.Figures6,8,10and12show the data on a linear and log-arithmic scale,corrected with the HERWIG+k t model,while Figures7,9,11and13 show the same data corrected with PHOJET.For all distributions the errors shown are the quadratic sum of the statistical errors of the measured quantity and the statistical errors of the correction factors.As an example,Table2shows the results for the W res distribution for the three experiments,listing the statistical error on the data and the statistical error on the correction factors,f,separately.

The experimental results from ALEPH,L3and OPAL agree with each other within errors for large regions in most of the variables studied.However,there are also re-gions where they signi?cantly di?er from each other,for example,in the region of W res<10GeV,E t,out<5GeV,for low charged multiplicities and low p t,trk in the low-Q2region.The level of agreement also depends on the Monte Carlo model used for correction.The agreement between the experiments is slightly better for the data corrected with PHOJET,than for the data corrected with HERWIG+k t.In the com-bination of the data,the di?erences between the measured distributions of the di?erent experiments will be used as an estimate of the systematic error.

There are signi?cant di?erences between the Monte Carlo distributions and the data,particularly in the low-Q2region.The PHOJET distributions lie consistently below HERWIG+k t,especially at the low end of the distributions,while the agreement of the tails in the high-Q2region is reasonable.In general the PHOJET predictions agree reasonably well with the data,corrected with PHOJET,for large values of the variables.However,there are large di?erences in the low-Q2region between the data, corrected with HERWIG+k t,and the HERWIG+k t predictions in all the distributions. For the W res,E t,out and p t,trk distributions(except in the region of low values,where the data are inconsistent)the di?erences between the experiments are much less than the HERWIG+k t?PHOJET di?erences.

Figures14and15show the corrected energy?ow as a function of pseudorapidity in the low-Q2and high-Q2region for the individual experiments compared to the

HERWIG+k t and PHOJET predictions.Following the energy?ow analyses at HERA,

√

the statistical errors for the energy?ow are taken as

are not very stable against variations of the event selection cuts such as the anti-tag condition or a maximum energy cut on the energy deposited in the forward detectors. The observed changes are much larger at the detector level than at the hadron level, leading to the conclusion that the modelling of the energy response to the hadronic energy in the forward region is poor.This can be understood since the sub-detectors covering this region have poor energy resolution for hadronic energies and no particle identi?cation.Therefore the uncertainty of the hadronic energy?ow in the forward region is larger than is indicated by the spread of the experiments and it is di?cult to draw?rm conclusions on the description by the Monte Carlo models.However,the data appear to lie consistently below the prediction of either generator.

5.2Modi?cation of the HER WIG model

As discussed above,the distribution of transverse momentum k t of the photon remnant with respect to the direction of the incoming photon has been altered,motivated by the ?ndings in photoproduction at HERA.At LEP,the modi?cation was initially studied as a possible improvement of the agreement between the HERWIG prediction and the high-Q2data of OPAL and ALEPH.While HERWIG+k t seems to reasonably describe the data in the high-Q2region for low and high values of E t,out,it overestimates the distribution for medium values of E t,out,as shown in Figure8.Even though the description of the energy?ow is improved with the HERWIG+k t generator,it fails to accurately describe the data over a wide range of the pseudorapidityη.

While the?xed limit of k2t,max=25GeV2is adequate for the high-Q2region,in the low-Q2region it introduces too much transverse momentum,which is most clearly seen in the transverse momentum distribution of the tracks in Figure12.Therefore the dynamical adjustment,HERWIG+k t(dyn),as discussed in Section2,has been introduced.As will be seen in the next section,when comparing with the combined LEP data,this change leads to an improved description of the data also for the low-Q2 region.

5.3Combined data

In this section the results from the individual experiments discussed in Section5.1are combined.In large ranges of the phase space the individual results agree within the statistical precision quoted,however there are also signi?cant di?erences as discussed above.These di?erences are expected because the previous analyses of the individual LEP experiments[1–4]showed that the systematic errors,which are not included above, dominate.Because the Monte Carlo models do not su?ciently well resemble the data, evaluating the experimental systematic errors of the measurements based on these models will not be very reliable.On the other hand a combined result is desirable in order to serve as a guidance for the model builders to improve on their Monte Carlo programs.Therefore,in a?rst attempt to make a combined measurement, the experimental systematic error is taken from the spread of the measured results, wherever they are signi?cantly di?erent on the basis of the statistical error alone.In this case the purely statistical error of the combined result is in?ated as discussed

to PHOJET and various predictions from HERWIG in Figures 16–25.The measured values are listed in Tables 3–12.The combination of the data follows the procedure recommended by the Particle Data Group in section 4.2.2of [20].Since this is a crucial point of the analysis and because speci?c choices have to be made in the combination,the procedure is brie?y discussed below.

The combined value for a given bin is calculated as the weighted average of the measurements of the individual experiments using the statistical errors to calculate both the weights and the error of the combined value.To calculate the average bin content x from the individual contents x i and their statistical errors σi the following procedure is applied.The average content is calculated from x is taken to be

1/√

x ?x i )2

.If in the tail of a distribution,for example,some experiments measure zero in a particular bin,then χ2/(N ex ?1),thereby taking the spread of

the experiments as an estimate of the experimental systematic uncertainty.Finally,to obtain the errors quoted the uncertainties due to the correction factors are added in quadrature.Since the same data sets are used by each experiment to calculate the correction factors,the corresponding errors are strongly correlated between the experiments.To take this into account,the error on the correction factors is included by taking the smallest quoted error of the individual experiments as an estimate of this systematic error,which is assumed to be 100%correlated amongst the experiments.Also in the combination of the results of the individual experiments the 1/N ·d E/d ηdistribution is treated slightly di?erently from the other distributions.There is a large scatter in the measured values of the di?erent experiments,especially in the forward region,as can be seen from Figures 14and 15.As a consequence there is also a large scatter in the scale factors listed in Tables 11and 12.To avoid the combination proce-dure manufacturing arti?cially small errors for bins where the measurements happen to coincide,the scale factor applied to obtain the combined measurement is taken as the average of the individual scale factors from three neighbouring bins centered around the bin under study.

It is apparent from Figures 16,18,20,22and 24,that the new HERWIG+k t (dyn)with the dynamical cut-o?lies much closer to the low-Q 2averaged data than the version of HERWIG+k t using the ?xed cut-o?.However,the di?erence between HERWIG+k t (dyn)and HERWIG default is rather small.

In the case of the energy ?ow none of the various HERWIG models is able to accurately describe the data.This suggests that even though the new HERWIG+k t (dyn)better describes most of the data distributions,the energy ?ow is still not well understood.

The PHOJET model,Figures 17,19,21,23and 25,describes the data reasonably well in both regions of Q 2,but underestimates the cross-section near the lower limit of the distributions.This is understood as a consequence of the high transverse momen-tum cut-o?of 2.5GeV for the scattered partons in the hard scattering matrix element.

events[21].

The energy?ow corrected with HERWIG+k t and with PHOJET Figures24and25, mostly agree with each other within errors,except in a few bins in the forward region. In this region the data corrected with PHOJET lie below the data corrected with HERWIG+k t in the region of the peak atη?2and above the?ow corrected with HERWIG+k t in the region ofη>2.5.

6Conclusion

For the?rst time the results of deep inelastic electron-photon scattering from three of the LEP experiments have been combined and compared to predictions from the PHOJET and the HERWIG models.It is found that the data from the ALEPH,L3 and OPAL experiments agree within statistical errors except near the edges of the distributions.Where the spread is larger than expected from the statistical errors,as, for example,for low charged multiplicities,this di?erence is taken as an estimate of the detector dependent systematic uncertainty of the measurement.

In the comparison of the data with the HERWIG+k t model the most striking discrepancy is seen in the distributions of the low-Q2region,where the HERWIG+k t model systematically overestimates the data.This discrepancy is found to be mainly due to the?xed cut-o?for the intrinsic transverse momentum of the quarks in the photon in the HERWIG+k t model.By dynamically adjusting the cut-o?according to the kinematics of the individual event in the HERWIG+k t(dyn)model the description of the data is signi?cantly improved,particularly in the low-Q2region.

The PHOJET model describes the data reasonably well in both regions of Q2,but underestimate the cross-section near the lower limit of the distributions,due to the high transverse momentum cut-o?for the scattered partons in the hard scattering matrix element.

The energy?ow of the data lies between the predictions of the HERWIG and PHOJET Monte Carlo models in the central regions of the detectors.In the forward region the Monte Carlo predictions lie systematically above the data.It should be noted,however,that it is di?cult to assess the systematic errors in this region be-cause of the poor resolution of the hadronic energy measured in the electromagnetic luminosity monitors.

The method of combining the data of several of the LEP experiments has proven useful to detect shortcomings of Monte Carlo models in the description of these data. For the HERWIG Monte Carlo this investigation already demonstrated that the changed distribution of transverse momentum k t of the photon remnant with respect to the di-rection of the incoming photon,the HERWIG+k t(dyn)model,gives a better descrip-tion of the LEP data.As the data distributions are corrected to the hadron level,they can be directly compared to the predictions of the Monte Carlo models,without the need of detector simulation,and thus can be used more easily by Monte Carlo model builders.

Acknowledgements

We wish to thank R.Engel and M.H.Seymour for valuable discussions and useful advice concerning the use of the Monte Carlo models.

References

[1]OPAL Collaboration,R.Akers et al.,Z.Phys.C61,199–208(1994);

OPAL Collaboration,K.Ackersta?et al.,Z.Phys.C74,33–48(1997);

OPAL Collaboration,K.Ackersta?et al.,Phys.Lett.B411,387–401(1997);

OPAL Collaboration,K.Ackersta?et al.,Phys.Lett.B412,225–234(1997).

[2]DELPHI Collaboration,P.Abreu et al.,Z.Phys.C69,223–234(1996).

[3]L3Collaboration,M.Acciarri et al.,Phys.Lett.B436,403–416(1998);

L3Collaboration,M.Acciarri et al.,Phys.Lett.B447,147–156(1999).

[4]ALEPH Collaboration,D.Barate et al.,Phys.Lett.B458,152–166(1999).

[5]C.Berger and W.Wagner,Phys.Rep.146,1–134(1987);

R.Nisius,Phys.Rep.332,165–317(2000).

[6]G.Marchesini et al.,https://www.doczj.com/doc/4c4610884.html,m.67,465–508(1992).

[7]R.Engel,Z.Phys.C66,203–214(1995);

R.Engel,J.Ranft,Phys.Rev.D54,4246–4262(1996).

[8]M.Gl¨u ck,E.Reya and A.Vogt,Phys.Rev.D45,3986–3994(1992);

M.Gl¨u ck,E.Reya and A.Vogt,Phys.Rev.D46,1973–1979(1992).

[9]https://www.doczj.com/doc/4c4610884.html,uber,L.L¨o nnblad and M.H.Seymour,Tuning MC Models to?t DIS eγ

Scattering Events,in Proceedings of Photon’97,10-15May1997,eds A.Buijs,

F.C.Ern′e,World Scienti?c,52–56(1997);

S.Cartwright,M.H.Seymour et al.,J.Phys.G24,457–481(1998).

[10]ZEUS Collaboration,M.Derrick et al.,Phys.Lett.B354,163–177(1995).

[11]M.H.Seymour,private communication.

[12]A.Capella,U.Sukhatme,C.I Tan,and J.Tran Thanh Van,Phys.Rep.236,

225–329(1994).

[13]T.Sj¨o strand,https://www.doczj.com/doc/4c4610884.html,m.82,74–89(1994).

[14]L3Collaboration,B.Adeva et al.,Z.Phys.C55,39–62(1992).

[15]Available:https://www.doczj.com/doc/4c4610884.html,/?knowles/HW/hwtune.html,July3,2000.

[16]ALEPH Collaboration,D.Decamp et al.,Nucl.Instr.and Meth.A294,121–171

(1990),Erratum-ibid.A303393(1991);

ALEPH Collaboration,D.Buskulic et al.,Nucl.Instr.and Meth.A360,481–506 (1995).

[17]L3Collaboration,B.Adeva et al.,Nucl.Instr.and Meth.A289,35–102(1990);

L3Collaboration,M.Acciarri et al.,Nucl.Instr.and Meth.A351,300–312(1994);

M.Chemarin et al.,Nucl.Instr.and Meth.A349,345–355(1994);

[18]OPAL Collaboration,K.Ahmet et al.,Nucl.Instr.and Meth.A305,275–319

(1991);

P.P.Allport et al.,Nucl.Instr.and Meth.A324,34–52(1993);

P.P.Allport et al.,Nucl.Instr.and Meth.A346,476–495(1994);

B.E.Anderson et al.,IEEE Transactions on Nuclear Science41,845–852(1994).

[19]Available:http://home.cern.ch/LEPQCD/gamma

L3

W res[GeV]dσ/d W res[pb/GeV]

3?419.21±0.405±0.541

13.54±0.560±0.51015.54±0.457±0.514

5?67.690±0.270±0.311

6.455±0.441±0.340

7.448±0.325±0.339

7?8 3.083±0.181±0.177

2.579±0.181±0.192

3.317±0.213±0.202

9?10 1.898±0.155±0.158

1.051±0.118±0.106 1.590±0.155±0.136

11?12 1.021±0.117±0.122

0.424±0.073±0.0590.873±0.113±0.100

13?140.525±0.087±0.088

0.390±0.083±0.0870.298±0.072±0.050

15?160.467±0.101±0.128

0.099±0.030±0.0220.205±0.064±0.050

17?180.057±0.040±0.016

0.115±0.054±0.0530.094±0.044±0.031

19?200.107±0.032±0.042

0.000±0.000±0.0000.145±0.055±0.075

21?220.024±0.013±0.011

s=91GeV,calculated in the kinematical range de?ned in the text.The data have been corrected with HERWIG+k t.The?rst error listed is the statistical error on the data only,the second one is the statistical error arising from the correction factors,f.

HERWIG+k t Data Data

W res[GeV]S dσ/d W res [pb/GeV] 3?420.25±1.064 6.557±0.646

14.10 4.146 5.304 1.301

5?68.622±0.792 3.510±0.302

7.732 5.115 2.979 1.006

7?8 3.832±0.626 1.764±0.175

4.106 3.534 1.6820.204

9?10 2.051±0.1720.854±0.152

2.323 2.0400.915 1.813

11?12 1.053±0.1270.595±0.154

1.224

2.5700.459 2.530

13?140.433±0.0710.231±0.065

0.653 1.3660.2670.967

15?160.247±0.0870.136±0.053

0.345 1.2020.1390.455

17?180.098±0.0320.078±0.075

0.168 1.0230.0640.359

19?200.039±0.0290.039±0.024

0.087 1.1170.0290.561

21?220.011±0.0090.009±0.007

PHOJET Data Data

W res[GeV]S dσ/d W res [pb/GeV] 3?419.06±0.545 6.266±0.594

11.550.978 3.5710.897

5?68.447±0.432 3.244±0.225

5.078 2.266 2.606 1.322

7?8 3.532±0.290 1.740±0.163

2.115 1.270 1.4900.391 9?10 1.531±0.1140.950±0.182

0.858 1.2200.6800.629 11?120.623±0.0720.363±0.073

0.366 3.2590.314 1.183 13?140.254±0.0390.175±0.041

0.2150.6000.1520.270 15?160.102±0.0230.098±0.055

0.0870.4220.0790.452 17?180.065±0.0250.051±0.022

0.054 1.9220.0390.035 19?200.044±0.0270.023±0.018

0.0280.9480.0380.443 21?220.016±0.0080.000±0.000

HERWIG+k t Data Data

E t,out[GeV]S dσ/d E t,out [pb/GeV]

0.0?0.50.266±0.0640.330±0.227

7.221 1.929 2.7260.733

1.0?1.518.97±0.875 6.647±0.907

27.75 2.13210.56 2.214

2.0?2.52

3.54±2.5679.330±0.712

18.34 6.627 6.7230.928

3.0?3.59.316±1.170

4.739±0.369

9.595 4.722 3.4050.653

4.0?4.5 4.481±0.473 1.782±0.202

4.939 1.214 1.8940.409

5.0?5.5 2.020±0.4310.830±0.132

2.855 2.1490.998 1.238

6.0?6.5 1.035±0.2250.513±0.108

1.4460.6610.5030.769

7.0?8.00.376±0.0620.517±0.068

0.4880.5960.211 1.051

9.0?10.00.093±0.0270.149±0.034

0.0950.8940.0640.000

11.0?12.00.058±0.0310.045±0.016

0.037 1.0110.0200.000

13.0?14.00.012±0.0140.004±0.003

0.0220.5160.0120.000 Table5:The combined di?erential cross-section dσ/d E t,out calculated in the kine-matical range de?ned in the text for the low-Q2and high-Q2regions.The data are corrected with the HERWIG+k t model.The HERWIG+k t prediction(MC)and the scale factor S are shown in addition.

PHOJET Data Data

E t,out[GeV]S dσ/d E t,out [pb/GeV]

0.0?0.50.421±0.0640.451±0.172

7.089 1.772 2.4650.058

1.0?1.518.87±0.602 6.298±0.749

25.34 1.8278.616 2.115

2.0?2.524.99±1.0288.496±0.735

10.25 2.176 4.4380.303

3.0?3.58.639±0.791

4.147±0.434

3.614 1.607 1.9960.665

4.0?4.5 3.968±0.331 1.522±0.192

1.5890.611 1.1270.808

5.0?5.5 1.644±0.2220.825±0.179

0.797 1.4130.594 1.408

6.0?6.50.900±0.2160.419±0.095

0.4230.8030.3750.178

7.0?8.00.376±0.0630.235±0.055

0.181 1.8540.1510.710

9.0?10.00.083±0.0150.134±0.028

0.0840.2800.0730.000

11.0?12.00.018±0.0090.055±0.016

0.048 1.4100.0340.000

13.0?14.00.036±0.0180.000±0.000

0.0300.1740.0190.000 Table6:The combined di?erential cross-section dσ/d E t,out calculated in the kine-matical range de?ned in the text for the low-Q2and high-Q2regions.The data are corrected with the PHOJET model.The PHOJET prediction(MC)and the scale factor S are shown in addition.

HERWIG+k t Data Data

N trk S dσ/d N trk [pb]

313.48±0.854 4.592±0.542

20.26 5.2357.1110.727

512.80±0.934 4.773±0.492

10.16 2.829 4.212 1.395

7 4.729±0.638 2.333±0.271

3.396 3.199 1.494 1.082

9 1.540±0.2370.845±0.204

1.121 1.8390.477

2.069

110.431±0.0970.156±0.046

0.346 1.5450.140 2.046

130.150±0.0320.047±0.031

0.0830.9860.045 1.203

150.037±0.0160.003±0.004

low-Q2high-Q2

MC MC

dσ/d N trk [pb]S

11.02 3.457 3.514 1.710

415.73±1.022 5.392±0.519

10.38 1.890 3.878 1.536

67.931±0.713 3.537±0.246

3.891 3.180 2.025 2.263

8 2.412±0.321 1.385±0.203

1.099

2.1510.735 1.917

100.684±0.1360.387±0.076

0.279 1.1710.179 1.263

120.127±0.0350.113±0.037

0.072 2.8290.056 1.060

140.030±0.0170.018±0.011

0.018 1.0540.0130.500 Table8:The combined di?erential cross-section dσ/d N trk calculated in the kine-matical range de?ned in the text for the low-Q2and high-Q2regions.The data are corrected with the PHOJET model.The PHOJET prediction(MC)and the scale factor S are shown in addition.

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计算机专业毕业生最好去向：谷歌、苹果、思科 3.加州大学伯克利分校 University of California-Berkeley位于加州伯克利(Berkeley, California)，建于1868年，是美国的一所公立研究型大学，加州大学伯克利分校还是世界数学、自然科学、计算机科学和工程学最重要的研究中心之一，拥有世界排名第1的理科、世界第3的工科和世界第3的计算机科学，其人文社科也长期位列世界前5。 2015年11月，QS发布了全球高校毕业生就业力排名，加州大学伯克利分校排名第八。据经济学家分析，一个在加州大学伯克利分校的工科学生和e799bee5baa6e997aee7ad94e78988e69d8331333433623139 一个没读过大学的人相比，在大学毕业20年后，该校毕业生的总收入会比没上过大学的人多110万美元。 计算机专业毕业生最好去向：谷歌、甲骨文、苹果 4.加州理工学院 California Institute of Technology位于加州帕萨迪纳市(Pasadena, California)，成立于1891年，是一所四年制的私立研究型学院。 该院研究生课程门门都出类拔萃，2010年U.S. News美国大学最佳研究生院排名中，加州理工学院的物理专业排名全美第1，化学第1，航空航天第1，地球科学第1，生物学第4，电子工程第5，数学第7，计算机科学第11，经济学第14。 加州理工学院不仅仅是工科好，在综合排名上，该校也能够排进前五十。该校的研发部门与NASA、美国国家科学基金会以及美国卫生与人类服务部有着密切的合作关系。 计算机专业毕业生最好去向：谷歌、英特尔、IBM 5.佐治亚理工学院 Georgia Institute of Technology位于佐治亚州亚特兰大市(Atlanta, Georgia)，是美国一所综合性公立大学，始建于1885年。与麻省理工学院及加州理工学院并称为美国三大理工学院。其中计算机科学专业全美排名第10，该校的电气与电子工程专业声誉不错。 计算机专业毕业生最好去向：IBM、英特尔、AT&T 6.伊利诺伊大学香槟分校 University of Illinois —Urbana-Champaign位于伊利诺伊州香槟市(Champaign, Illinois)，创建于1867年，是一所享有世界声望的一流研究型大学。 该校很多学科素负盛名，其工程学院在全美乃至世界堪称至尊级的地位，始终位于美国大学工程院排名前五，几乎所有工程专业均在全美排名前十，电气、计算机、土木、材料、农业、环境、机械等专业排名全美前五。

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斯坦福大学创业成长课

斯坦福大学创业成长课 书籍简介 想知道最有用的创业课——斯坦福大学和著名的硅谷孵化器YC公司研发的创业课程是怎么样的吗？想知道李笑来老师丰富的创业经历中总结的最热血沸腾也最精华的部分吗？这本书将为你揭晓所有的答案，把神秘而不可知的创业成功要素系统化、具象化，为你解决创业过程中的各种迷惑。 关于作者 李笑来，前新东方名师，著名天使投资人，中国比特币首富，新东方时期著有《TOEFL核心词汇21天突破》，为广大考生必备书籍，后著有《把时间当作朋友》、《新生——七年就是一辈子》等个人成长相关书籍，他的《通往财富自由之路》专栏订阅量约21万，总营业额超4000万元。 核心内容 一是创业者具备的特点； 二是创业三要素。

前言 你好，这期音频为你解读的是《斯坦福大学创业成长课》，这本书约18万字，我会用大约10分钟的时间，为你讲述书中精髓：创业者如何从零到一，一步一步走向成功。 在全民创业的时代，死守着一份工资，望着显而易见的职业晋升天花板，看着朋友们毅然决然地离开单位，一拳一脚地创业成功，开豪车、住豪宅，心里是无比的羡慕。为什么有些人就能创业成功？而大多数人只能看着别人吃肉，自己却只能在“是否要创业”、“怎么创业”的矛盾和纠结中浑浑噩噩地过日子？ 我们今天要讲的《斯坦福大学创业成长课》将完美解答这些问题。本书基于美国硅谷顶尖孵化器YC和斯坦福大学联手打造的“如何创业”的课程，总结互联网趋势下产品、市场、团队等方面的创业干货，对有创业意愿的人有极大参考价值。 本书的作者李笑来创业经验丰富，通过财富积累，李笑来成为中国比特币首富，并创立比特基金，专注于互联网、比特币相关领域。 好，接下来我们来说这本书的核心内容吧。我将从两部分为大家讲解，第一部分是创业者具备的特点；第二部分是创业的三要素。 第一部分：创业者具备的特点 创业者和一般人究竟有什么不一样？《斯坦福大学创业成长课》总结了创业者的三个特点，这些特点让他们出类拔萃、与众不同。 第一个特点就是关注进步。 人的关注点分为两种，分别是“关注进步”和“关注表现”，乍看上去差不多，其实对人生造成的影响可谓是天壤之别。 “关注进步”的人焦点在于自己今天是否比昨天强，是不是又学会了新的东西；而“关注表现”的人焦点在于自己在人群里是不是表现的最好，别人对自己的看法如何。因为太在意自己一定要表现得“好”，所以有可能失败的事情，他们就不会去尝试，从而错失很多成长的机会。 创业者只有做到不在意别人的眼光，培养“关注进步”的习惯，才能获得持续的成长。 第二个特点是好奇心旺盛，善于学习。 在任何创业的领域，都需要深度了解行业技术，特别是在各行各业发展日新月异的现代，保持终身学习的习惯非常重要。

4. 美国的宗教历史-清教徒

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美国排名前100的大学

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