The bulk Lorentz factor crisis of TeV blazars evidence for an inhomogeneous pileup energy

A.680道英文题(后面附加有中文说明)1..Which flight conditions of a large jet airplane create the most severe flight hazard by generating wingtip vortices of the greatest strength?A.Heavy,slow,gear and flaps up.B.Heavy,slow,gear and flaps down.C.Heavy,fast,gear and flaps down.A X2..In a decision-making process,a participatory leaderA.allows each team member to have a say and to participate in team processes.B.tends to make all team decisions and controls all resources.C.may ultimately decide the team's actions,but seldom takes into consideration the team members'experience,knowledge,and preferences.A X3..The perception of color is a function of theA.cones on the retina and is diminished in dim ambient lighting.B.rods on the retina and is diminished in dim ambient lighting.C.cones on the retina and is diminished in bright lighting conditions.A X4..Hypoxia may be caused byA.fly with a head cold.B.breathing too quickly and/or too deeply for therequirements of the body.C.flying at an altitude where the partial pressure of oxygen is too low.C X5..(According to Figure 4) At Shanghai,which description is correctA.The visibility is 800 meters,the sea level pressure is 996 hPa,B.The visibility is 8 kilometers,the QNH is 999.6 hPa,C.The visibility is 8 kilometers,the sea level pressure is 999.6 hPa,C X6.At which speed will increasing the pitch attitude cause an airplane to climb?A.Low speed.B.High speed.C.Any speed.B X7..A plane,MH 160°,receive this ATC clearance: "... HOLD EAST OF THE ABC VORTAC ON THE ZERO NINER ZERO RADIAL...",What is therecommended procedure to enter the holding pattern?A.Teardrop onlyB.Direct onlyC.Parallel onlyC X8..The maximum duty time in 24 consecutive hours that a carrier may schedule a pilot in a three pilot crew (including a second-in-commander pilot) without a rest period isA.16hoursB.17 hoursC.18 hoursA X9..A person whose duties include the handing or carriage of dangerous articles and/or magnetized materials must have satisfactorily completed an established and approvedtraining program within the precedingA.6 calendar months.B.12 calendar months.C.24 calendar months.B X10..Which dispatch requirement applies to an international air carrier that isscheduled for a 10 hours IFR flight?A.No alternate airport is required if the visibility at thedestination airport is desired to be at least 4,800m.B.An alternate airport is required.C.An alternate airport is not required if the ceiling at the destination airport is at least 600m AGL.B X11..If a flight engineer becomes incapacitated duringflight,who may perform the flight engineer's duties?A.The second in command only.B.Any flight crewmember, if qualified.C.Either pilot, if they have a flight engineer certificate.B X12..(Refer to Figure 1) According to the aeronautical weather report on figure 1,the QNH for ZUUU isA.998 hPaB.1099.8 hPaC.999.8 hPaA X13..Which condition will for the formation of radiation fog?A. Moist, stable air being moved over gradually rising ground by a wind.B. A clear sky, little or no wind,and high relative humidity.C. Moist air moves over colder ground or water.B X14..If a pilot suspects that he/she is suffering the effects of hypoxia,the most appropriate remedy would bee supplement oxygen or descend immediately to a low levelB.voluntarily increase the depth of breathing to induce more oxygen into the lungsC.voluntarily increase the breathing rate to increase the oxygen uptakeA X15..For the purpose of testing the flight recorder system.A.A minimum of 1 hour of the oldest recorded data must be erased to get a valid testB.A total of 1 hour of the oldest recorded data accumulated at the time of testing may be erasedC.A total of no more than 1 hour of recorded data may be erasedB X16.What effect does the leading edge slot in the wing have on performance?A. Decrease profile drag.B. Changes the stalling angle of attack to a higher angle.C. Decelerates the upper surface boundary layer air.B X17.. Under what condition should a pilot on IFR advise ATC of minimum fuel status?A. When the fuel supply becomes less than that required for IFR.B. If the remaining fuel suggests a need for traffic or landing priority.C. If the remaining fuel precludes any undue delay.C X18.. In the Northern hemisphere, if a pilot makes along-distance flight from east to west, under which of the following conditions,A.(接正文encounter against the wind forming by air pressure system?) when the airplane is in the south of high pressure system and in the north of low pressure system.B. When the airplane is in the north of high pressure system and in the south of low pressure system.C. When the airplane is in the north of high pressure and low pressure systems .B X19.. An alternate airport for departure is requiredA.if weather conditions are below authorized landing minimums at the departure airport.B.when the weather forecast at the estimated time ofdeparture is for landing minimums only.C.when destination weather is marginal IFR.A X20.. [Refer to Figures 4-50,4-51,4-52,4-53, and 4-54.] What is the total fuel required at .80 Mach?A.22,836 pounds.B.22,420 pounds.C.22,556 pounds.B X21.. Which is a definition of V2 speed?A.Takeoff decision speed.B.Takeoff safety speed.C.Minimum takeoff speed.B X22.. What is the approximate rate unsaturated air will cool flowing upslope?A. 3℃per 1,000 feet.B. 2℃per 1,000 feet.C. 4℃per 1,000 feet.A X23. An airport approved by the Administrator for use by an air carrier certificate holder for the purpose of providing service to a community when the regular airport is notavailable is a/an:A.destination airport.B.provisional airport.C.alternate airport.B X24.. (Refer to Figure 6-7) If the en route altitude of an aircraft is FL118, what is the altitude when the aircraft operates to DAWANGZHUANG along 007oA.FL118.B.FL128.C.FL138.A X25.. Who is responsible for the issue of Series D NOTAMs?AFC.B.Area flight information center.C.Airport flight information office.C X26..What temperature condition is indicated if precipitation in the form of wet snow occurs during flight?A. the temperature is above freezing at flight altitude.B. The temperature is above freezing at higher altitudes.C. There is an inversion with colder air below.A X27.Which ground components are required to be operative fora Category II approach in addition to LOC glide slope, marker beacons, and approach lights?A.Radar and RVR.B.RCLS and REILC.HIRL, TDZL, RCLS, and RVR.C X28.If an aircraft level turns at an angle of bank of 30 degree , the load factor isA.1Gs.B.2Gs.C.1.4GsC X29.. The ATS unit must ensure that pilots are kept informed of any change in the status of airport facilities_______________.A. at their destinationsB. at their alternate aerodromesC. A and BC X30.. (Refer to Figure 6-5) If an aircraft is estimated to arrive WEIXIAN at 1300z, pilot should contact ZHENGZHOU CONTROL on the frequency ofA.122.20MHz.B.8897KHz.C.3016KHz.C X31..(according to figure 2), the forcasting visibility at ZSSS is____A. 5000 m between 00Z-05Z, and 3000 m at other timeB. 5000 m between 00Z-09ZC. 5000 m between 00Z-05Z, 5000 m above at other timeA X32. By regulation, who shall provide the pilot in command of a domestic or flag air carrier airplane information concerning weather, and irregularities of facilities and services?A.The aircraft dispatcher.B.Air route traffic control center.C.Director of operations.A X33.. If the wind direction measured by the weather station is 270°,the optimum takeoff and landing direction is .A.from east to westB.from west to eastC.from north to southA X34.What characteristic should exist if an airplane is loaded tothe rear of its CG range?A.Sluggish in aileron control.B.Sluggish in rudder controlC.Unstable about the lateral axisC X35. Which is a definition of the term "crewmember"?A.Only a pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.B.A person assigned to perform duty in an aircraft during flight time.C.Any person assigned to duty in an aircraft during flight except a pilot or flight engineer.B X36.. The most important restriction to the operation of turbojet or turboprop engines isA.Limiting compressor speed.B.Limiting Turbine Inlet Temperature (TIT).C.Limiting torque.B X37. If it becomes necessary to shut down one engine on a domestic air carrier three-engine turbojet airplane, thepilot in commandA. must land at the nearest suitable airport, in point of time,at which a safe landing can be made.B. may continue to the planned destination if approved by the company aircraft dispatcher.C. may continue to the planned destination if this is considered as safe as landing at the nearest suitable airport.C X38. In a 24-hour consecutive period, what is the maximum time, excluding briefing and debriefing, that an airline transport pilot may instruct other pilots in air transportationservice?A.6 hours.B.8 hours. 2C.10 hours.B X39.. [Refer to Figures 4-46, 4-47 and 4-48.] What is the ETE from Chicago Midway Airport to Greater Buffalo Intl?A.2 hours 12 minutes.B.2 hours 15 minutes.C.2 hours 18 minutes.A X40.. You should advise ATC of minimum fuel status when your fuel supply has reached a state where, upon reaching your destination, you cannot accept any undue delay.A. This will ensure your priority handling by ATC.B. ATC will consider this action as if you had declared an emergency.C. If your remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, declare an emergency due to low fuel and report fuel remaining in minutes.C X41.. (Refer to Figure 7) In this chart, ISOL EMBD CB 340/XXX meansA. Some places have CBs, CBs with little or no separationB. Isolated cumulonimbus embedded in layers of other clouds, the top of the cumulonimbus is 34000 feet, the base is unknownC. The airplane is embedded in layers of clouds, the top of the cumulonimbus is 34000 feet, the base is unknownB X42.Within what frequency range dies the localizer transmitter of the ILS operate?A.108.10 to 118.10 MHZB.108.10 to 111.95 MHZC.108.10 to 117.95 MHZ.B X43..Which of the following characteristics heatthunderstorm?A.It moves with the weather system.B.It covers small area and is isolated with openingsC. It strengthens at night and weakens in the day on landB X44.. What is the time limitation for filing flight application?A.At least before 1500 Beijing Time prior to the departure date.B.At least before 1700 Beijing Time prior to the departure date.C.At least before 1200 Beijing Time prior to the departure date.A X45.What is the purpose of an elevator trim tab?A.Provide horizontal balance as airspeed is increased toallow hands-off flight.B.Adjust the speed tail load for different airspeeds in flight allowing neutral control forces.C.Modify the downward tail load for various airspeeds inflight eliminating flight-control pressures.C X47.．Hypoxia is always accompanied byA. dizzinessB.a degradation in the performance of a pilotC.vomitingB X48.The "runway hold position" sign denotesA.An area protected for an aircraft approaching a runwayB.An entrance to runway from a taxiwayC.Intersecting runwaysC X49.. An alternate airport must be listed in the dispatch and flight release for all international operation air carrier flights longer thanA.7 hours.B.8 hours.C.6 hours.C X50.．Carbon monoxide is dangerous becauseA.it displace oxygen from the blood's red cellsB.it is highly acidic and attacks the lining of the lungsC.it displaces oxygen from the lungs causing suffocationA X51.. In flight, pilots find forane clouds consisting of cloud bar and cloud band with flat floor and piled clouds on the top of some clouds. The descriptive cloud should be.A. cumulus congestusB. cumulostratusC. towering cloudsC X52.. What condition produces the most frequent type ofground-or surface-based temperature inversion?A. The movement of colder air under warm air or the movement of warm air over cold air.B. Widespread sinking of air within a thick layer aloft resulting in heating by compression.C. Terrestrial radiation on a clear, relatively calm night.C X53.．What is a symptom of carbon monoxide poisoning?A.Rapid, shallow breathing.B.Pain and cramping of the hands and feet.C.Dizziness.C X54.．Hypoxia is the result of which of these conditions?A.Insufficient oxygen reaching the brain.B.Excessive carbon dioxide in the bloodstream.C.Limited oxygen reaching the heart muscles.A X55.Which "rule-of-thumb" may be used to approximate therate of descent required for a 3 glide path?A.5times groundspeed in knots.B. 8times groundspeed in knots.C.10 times groundspeed in knots.A X56.A pilot of a high-performance airplane should be aware that flying a steeper-than-normal VASI glide slope angle may result inA. A hard landing.B. Increased landing rollout.C. Landing short of the runway threshold.B X57. A domestic air carrier airplane lands at an intermediate airport at 1815Z. The latest time it may depart without a specific authorization from an aircraft dispatcher isA.1945Z.B.1915Z.C.1845Z.B X58.. An aircraft that encounters a headwind of 45knots, withina microburst, may expect a total shear across the microburst ofA. 40 knotsB. 80 knotsC. 90 knotsC X59.．Which of the following is not the tip for good SA management during the flight?A.Resolve discrepancies- contradictory data or personal conflicts.B.Fixation-focusing on any one thing to the exclusion of everything else.C.Monitor and evaluate current status relative to our plan.B X60.. If the landing minimums for a NDB approach shown on the IAP chart are visibility 2,000m and MDA 120m, which minimums apply when you actually divert to this airport?A.Visibility 2,800m and MDA 180m.B.Visibility 3,600m and MDA 240m.C.Visibility 2,000m and MDA 120m.C X61. A pilot flight crewmember, other than pilot in command, must have received a proficiency check or line-oriented simulator training within the precedingA.6 calendar months.B.12 calendar months.C.24 calendar months.C X62.. (Refer to Figure 6-1) Which approach lighting is available for VOR/DME Rwy 36R?A.HIALS.B.HIALS with PAPI.C.PAPI.B X63.Holding position signs haveA.White inscriptions on a red backgroundB.Red inscriptions on a white backgroundC.Yellow inscriptions on a red backgroundA X64.．A common source of human error is the false hypothesis. Under certain conditions this is more or less likely than at other times. From the following list, select the situation least likely toA.(续正文，result in a person arriving at a falsehypothesis)when expectancy of an event is highB.after a period of intense concentrationC.during normal operationC X65..Which airplane performance characteristics should berecognized during takeoff when encountering a tailwind shear that increases in intensity?A. loss of, or diminished, airspeed performanceB. decreased takeoff distanceC. increased climb performance immediately after takeoffA X66.Which airplanes are required to be equipped with a ground proximity warning glide slope deviation alerting system?A.All turbine powered airplanesB.Passenger -carrying turbine-powered airplanes onlyrge turbine-powered airplanes onlyA X67..During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?A. cumulusB. dissipatingC. matureB X68.When are outboard ailerons normally used?A.Low-speed flight only.B.High-speed flight only.C.Low-speed and high-speed flight.A X69.. What does the throttle opening of aturbo-charged-reciprocating engine control?A.Supercharger gear ratio.B.Exhaust gas discharge.C.The desired manifold pressure.C X70.During an en route descent in a fixed-thrust andfixed-pitch attitude configuration, both the ram air input and drain hole of the pilot system become completely blocked by ice. What airspeed indication can be expected?A.Increase in indicated airspeed.B.Decrease in indicated airspeed.C.Indicated airspeed remains at the value prior to icingB X71. An applicant who is taking a practical test for a type rating to be added to a commercial pilot certificate, in an approved simulator, isA.required to have a first-class medical certificate.B.required to have a second-class medical certificate.C.not required to have a medical certificate.C X72..If the aircraft enters the strong downdraft burst, where is the aircraft expected to meet the strongest downdraft?A. in the center of strong downdraft burstB. when it enters the strong downdraft burstC. when leaves the strong downdraft burstA X73.. It should be reported without ATC request thatA. When unable to climb at a rate of at least 500 feet per minute.B. When unable to descend at a rate of at least 1000 feet per minute.C. When unable to climb or descend at a rate of at least 600 feet per minute.A X74.. [Refer to Figure 4-28.] How much will landing distance be reduced by using 15o of flaps rather than 0o flaps at a landing weight of 115,000 pounds?A.500 feet.B.800 feet.C.2,700 feet.B X75.．The time of useful consciousness(TUC) is affected by many factors, such as flight altitude, climbing rate, pilot'sactivity level, pilot'sA.(续正文，health, and whether the pilot smoking or not. Thestatement is )rightB.wrongA X76. (Refer to Figure 2-12) what is the runway distance remaining at "A" for a nighttime takeoff on runway 9?A.1,000 feetB.2,000 feetC.2,500 feetB X77.. Maximum range performance of a turbojet aircraft is obtained by which procedure as aircraft weight reduces?A.Increasing speed or altitude.B.Increasing altitude or decreasing speed.C.Increasing speed or decreasing altitude.B X78..Which type of weather conditions are covered in the Convective SIGMETA. Embedded thunderstorms, severe turbulenceB. Cumulonimbus clouds, light turbulenceC. severe icing, surface visibility lower than 5000 metersA X79. When a pilot plans a flight using NDB NAVAIDS. Which rule applies?A.The airplane must have sufficient fuel to proceed. by means of VOR NAVIDS, to a suitable airport and land.B.The pilot must be able to return to the departure airport using other navigation radios.C.The airplane must have sufficient fuel to proceed, by means of VOR NAVAIDS, to a suitable airport and complete an instrument approach by use of the remaining airplane radio system.C X80.. What is an area identified by the term "clearway"?A.centrally located about the extended centerline and under airport authorities, which does not contain obstructions and can be considered when calculating takeoff performance.B.An area, at least the same width as the runway, capable of supporting an airplane during a normal takeoff.C.An area beyond the takeoff runway, which is able to support the airplane, for use in decelerating the airplane during an aborted takeoff.A X81. A crewmember who has served as second-in-command on a particular type airplane (e.g., B737-300), may serve aspilot-in-command upon completing which training program?A.Upgrade training.B.Recurrent training.C.Initial training.A X82.. Which points should be report to ATC without request?A. when leaving the final approach fix outbound.B. when leaving an assigned holding fix.C. when leaving the final approach fix outbound, or when leaving an assigned holding fix.C X83.. What is the correct symbol for minimum unstick speed?A.VMU.B.VMD.C.VFC.A X84.．The two different types of light sensitive elements on the retina are classified asA.rods which are sensitive to color and cones which work best in dim light.B.cones which are sensitive to color and rods which work best in dim light.C.rods and cones both of which are responsible for color vision.B X85.(Refer to Figures 2-4 and 2-5)To which aircraft position does HSI presentation "A" correspond?A.9and6B.9 onlyC.6 onlyA X86.．Which of the following is the clue of SA weaken or loss during the flight?A.Fixation-focusing on any one thing to the exclusion of everything else.B.Adhere to standard operating procedures.C.Meet expected checkpoint on flight plan or profile-ETA, fuel burn, etC．as far as possible.A X87..Which type clouds are indicative of very strong turbulence?A. nimbostratus.B. Standing lenticular.C. Cirrocumulus.B X88.. What effect will an increase in altitude have upon the available equivalent shaft horsepower (ESHP) of a turboprop engine?A.Lower air density and engine mass flow will cause a decrease in power.B.Higher propeller efficiency will cause an increase in usable power (ESHP) and thrust.C.Power will remain the same but propeller efficiency will decrease.A X89.. You can't enter tower controlled airspace under IFR weather conditions unless you have filed an IFR flight plan andA.slowed down to the final approach IAS.B.received an ATC clearance.C.climbed to the appropriate altitude.B X90.. Series C NOTAMs of Class 2 must be disseminated to domestic area flight information center NOTAMs officeA.25 days ago.B.15 days ago.C.7 days ago.B X91..(according to figure 2), at ZBAA, the max predicting wind speed is___.A. 17 m/sB. 8 m/sC. 6 m/sA X92.. [Refer to Figure 4-28.] What is the ground roll when landing with 5o of flaps at a landing weight of 142,500 pounds?A.1,750 feet.B.2,100 feet.C.2,500 feet.C X93.．Which of the following is not normally a symptom of hypoxia?A.increased visual fieldB.An increase in breathing rateC.Sleepiness or frequent yawningA X94.. (Refer to Figure 6-3) The true direction of Rwy 35 at PUDONG isA.342o.B.347o.C.352o.A X95.. What effect would a change in air density have ongas-turbine-engine performance?A.As air density decreases, thrust increases.B.As air density increases, thrust increases.C.As air density increases, thrust decreases.B X96. When is DME required for an instrument flight?A.At or above 24000 feet MSL if VOR navigational equipment is requiredB.In terminal radar service areasC.Above 12,500 feet MSLA X97. . (Refer to Figure 6-2) Which approach lighting isavailable for ILS/DME Rwy 36L?A.HIALS with PAPI.B.HIALS.C.PAPI.A X98.. (According to Figure 1) which station reports the max wind speedA.ZSSSB.ZUUUC.ZWWWC X99.What is a characteristic of longitudinal instability?A.Pitch oscillations becoming progressively greater.B.Bank oscillations becoming progressively greater.C.Aircraft constantly tries pitch down.A X100.. (Refer to Figure 6-3, 6-4) What distance is available for takeoff on Rwy 17 at PUDONG?A.12,093 feet.B.12,097 feet.C.13,123 feet.C X101..Crew resource management is a process using allavailable information and resources, i.e. equipment, procedures and people, to achieve a safe andA.(续正文，efficient flight operation. The statement is)rightB.wrongA X102.. [Refer to Figure 4-41.] What is the approximate landing weight for Operating Conditions below? WEIGHT (START TO ALT): 87,000,DISTANCE (NM): 370,WIND COMPONENT: 60HW,HOLDINGTIME AT ALT (MIN): 15A.80,850 pounds.B.85,700 pounds.C.77,600 pounds.A X103.．(Refer to Figure 1) What weather condition is reported at Urumchi (ZWWW)A. Strong wind with showerB. Snow and rainC. Strong west wind and blowing snowC X104.. [Refer to Figure 4-28 and 4-29.] What approach speed and landing distance will be needed when landing at a weight of 140,000 pounds with 15o of flaps?A.123 knots and 3,050 feet.B.138 knots and 3,050 feet.C.153 knots and 2,050 feet.B X105.If a required instrument on a multiengine airplane becomes inoperative, which document dictates whether the flight may continue en route?A. An approved Minimum Equipment list for the airplane.B. Original dispatch release.C. Certificate holder's manual.C X106.. [Refer to Figure 4-34.] What are the recommended IAS and EPR settings for holding under Operating Conditionsbelow? ,ALTITUDE: 30,000,WEIGHT (*1000): 92.5,ENGINES OPERATING: 2,HOLDING TIME (MIN): 10A.221 knots and 1.83 EPR.B.210 knots and 1.69 EPR.C.217 knots and 1.81 EPR.B X107.. How often is SNOWTAM broadcast to distant centers?A.Hourly.B.One hour and a half a time.C.30 minutes a time.A X108..When light passes through the lens it is brought to focus at the back of the eyeball on theA.retinaB.corneaC.irisA X109..When is the course deviation indicator (CDI) considered to have a full-scale deflection?A.When the CDI deflects from full-scale left to full-scale tight, or vice versa.B.When the CDI deflects from the center of the scale tofull-scale left or right.C.When the CDI deflects from half-scale left to half-scale right, or vice versa.B X110.．Effective CRM has some characteristics, which of the following is right description about it?A.CRM is a process using all available information and resources, i.e. equipment, procedures and people, to achieve a safe and efficient flight operation.B.CRM can be blended into all forms of aircrew trainingC.A and BC X111.. [Refer to Figure 4-25.] What is the maximum landing weight which will permit stopping 1,500 feet short of the end of a 4,950-foot dry runway with reversers and spoilers inoperative?A.119,000 pounds.B.136,000 pounds.C.139,000 pounds.C X112. Who is required to submit a written report on a deviation that occurs during an emergency?A. Person who found the emergency.B. Person who heard the emergency.C. Pilot in command.C X113..Northwest wing can be presented as .A. 200°or NWB. 315°or NWC. 135°or SEB X114..What characterizes a transient compressor stall?A.Loud, steady roar accompanied by heavy shuddering.B.Sudden loss of thrust accompanied by a loud whine.C.Intermittent "bang," as backfires and flow reversals take place.C X115..Which of the following is not the way of increasing MCRIT in jet transport designsA. give the wing a lower camberB. increase wing sweep.C.add slatsC X116Under what condition is VMC the highest?A.Gross weight is at the maximum allowable value.B.CG is at the most rearward allowable position.C.CG is at the most forward allowable position.。

《星海求知：天文学的奥秘（尔雅）》在线作业
下列哪个对象在宇宙中的占比最大?( )
A:暗物质
B:可见物质
C:暗能量
D:星系
参考选项：C
关于球状星团,下列说法错误的是( )。

A:整体是规则的球形
B:由上万至几百万的星体组成
C:由演化至晚期的恒星聚集而成
D:尺度为200—300Ly
参考选项：D
超新星爆发时,其亮度变化会超过( )个星等以上。

A:10
B:15
C:20
D:25
参考选项：C
白矮星的密度是水的()倍。

A:10
B:1000
C:1000000
D:10的15次方
参考选项：C
根据拉普拉斯的数学模型,成为黑洞的天体的性质不包括()。

A:密度与地球相等
B:质量是太阳的250倍
C:直径是太阳的250倍
D:逃逸速度等于光速
参考选项：B
天文单位指的是()与太阳的平均距离。

A:地球
B:月球
C:水星
D:冥王星
参考选项：A
1。

南开大学智慧树知到“选修课”《前进中的物理学与人类文明(尔雅)》网课测试题答案（图片大小可自由调整）第1卷一.综合考核(共15题)1.对于热力学定律的说法错误的是()。

A.热力学第二定律可以从第一定律中推导出来B.热力学第二定律可以解释热力学过程的限度问题C.热力学第二定律可以解释热力学过程的方向问题D.热力学第一定律可以确定能量转化和守恒的问题2.一般可见光的波长在400-700 nm，而原子的尺度为0.1nm，所以我们看不见原子。

()A.正确B.错误3.一辆816kg的大众需要以多快的速度行驶才具有一台2650kg的凯迪拉克以16.0km/h行驶时的动量?()A.20B.60C.51.9D.404.牛顿第二定律F=ma中m是()。

A.引力质量B.惯性质量C.AB一样D.都不是5.重力场中，微粒数量随高度的关系是海拔越高，数量越少。

()A.正确B.错误6.狭义相对论是谁提出来的?()A.玻尔兹曼B.基尔霍夫C.爱因斯坦D.麦克斯韦7.粒子的衍射是由光粒子间的相互作用引起。

()A.正确B.错误8.交流电路中，电阻，电容和电感均会产生阻抗。

()A.正确B.错误9.物理可以分为基础物理和应用物理。

()A.正确B.错误10.哥本哈根学派的量子力学统计诠释是由下列哪位科学家提出的?()A.波尔B.波恩C.波色D.玻尔兹曼11.很多物理量同时具有宏观解释与微观意义如动量，能量等。

()A.正确B.错误12.扩散要求两层介质满足怎样的条件?()A.体积不同B.质量不同C.密度不同D.粘滞系数不同13.1958年，核动力潜艇Nautilus从波特兰出发横跨大西洋到英国，用了6天12个小时航行了5068km。

其平均速度为()。

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DESY02-096ISSN0418-9833 July2002Search for Excited Electrons at HERAH1CollaborationAbstractA search for excited electron(e∗)production is described in which the electroweak decayse∗→eγ,e∗→eZ and e∗→νW are considered.The data used correspond to anintegrated luminosity of120pb−1taken in e±p collisions from1994to2000with the H1detector at HERA at centre-of-mass energies of300and318GeV.No evidence for a signalis found.Mass dependent exclusion limits are derived for the ratio of the couplings to thecompositeness scale,f/Λ.These limits extend the excluded region to higher masses thanhas been possible in previous direct searches for excited electrons.To be submitted toPhysics Letters BC.Adloff33,V.Andreev24,B.Andrieu27,T.Anthonis4,A.Astvatsatourov35,A.Babaev23,J.B¨a hr35,P.Baranov24,E.Barrelet28,W.Bartel10,S.Baumgartner36,J.Becker37,M.Beckingham21,A.Beglarian34,O.Behnke13,A.Belousov24,Ch.Berger1,T.Berndt14,ot26,J.B¨o hme10,V.Boudry27,W.Braunschweig1,V.Brisson26,H.-B.Br¨o ker2,D.P.Brown10,D.Bruncko16,F.W.B¨u sser11,A.Bunyatyan12,34,A.Burrage18,G.Buschhorn25, L.Bystritskaya23,A.J.Campbell10,S.Caron1,F.Cassol-Brunner22,D.Clarke5,C.Collard4, J.G.Contreras7,41,Y.R.Coppens3,J.A.Coughlan5,M.-C.Cousinou22,B.E.Cox21,G.Cozzika9,J.Cvach29,J.B.Dainton18,W.D.Dau15,K.Daum33,39,M.Davidsson20,B.Delcourt26,N.Delerue22,R.Demirchyan34,A.De Roeck10,43,E.A.De Wolf4,C.Diaconu22,J.Dingfelder13,P.Dixon19,V.Dodonov12,J.D.Dowell3,A.Droutskoi23,A.Dubak25,C.Duprel2,G.Eckerlin10,D.Eckstein35,V.Efremenko23,S.Egli32,R.Eichler32, F.Eisele13,E.Eisenhandler19,M.Ellerbrock13,E.Elsen10,M.Erdmann10,40,e,W.Erdmann36, P.J.W.Faulkner3,L.Favart4,A.Fedotov23,R.Felst10,J.Ferencei10,S.Ferron27,M.Fleischer10,P.Fleischmann10,Y.H.Fleming3,G.Fl¨u gge2,A.Fomenko24,I.Foresti37,J.Form´a nek30,G.Franke10,G.Frising1,E.Gabathuler18,K.Gabathuler32,J.Garvey3,J.Gassner32,J.Gayler10,R.Gerhards10,C.Gerlich13,S.Ghazaryan4,34,L.Goerlich6,N.Gogitidze24,C.Grab36,V.Grabski34,H.Gr¨a ssler2,T.Greenshaw18,G.Grindhammer25, T.Hadig13,D.Haidt10,L.Hajduk6,J.Haller13,B.Heinemann18,G.Heinzelmann11,R.C.W.Henderson17,S.Hengstmann37,H.Henschel35,R.Heremans4,G.Herrera7,44,I.Herynek29,M.Hildebrandt37,M.Hilgers36,K.H.Hiller35,J.Hladk´y29,P.H¨o ting2,D.Hoffmann22,R.Horisberger32,A.Hovhannisyan34,S.Hurling10,M.Ibbotson21,C¸.˙Is¸sever7, M.Jacquet26,M.Jaffre26,L.Janauschek25,X.Janssen4,V.Jemanov11,L.J¨o nsson20,C.Johnson3,D.P.Johnson4,M.A.S.Jones18,H.Jung20,10,D.Kant19,M.Kapichine8,M.Karlsson20,O.Karschnick11,J.Katzy10,F.Keil14,N.Keller37,J.Kennedy18,I.R.Kenyon3, C.Kiesling25,P.Kjellberg20,M.Klein35,C.Kleinwort10,T.Kluge1,G.Knies10,B.Koblitz25, S.D.Kolya21,V.Korbel10,P.Kostka35,S.K.Kotelnikov24,R.Koutouev12,A.Koutov8,J.Kroseberg37,K.Kr¨u ger10,T.Kuhr11,mb3,ndon19,nge35,ˇs toviˇc ka35,30,ycock18,E.Lebailly26,A.Lebedev24,B.Leißner1,R.Lemrani10,V.Lendermann10,S.Levonian10,B.List36,E.Lobodzinska10,6,B.Lobodzinski6,10,A.Loginov23,N.Loktionova24,V.Lubimov23,S.L¨u ders37,D.L¨u ke7,10,L.Lytkin12,N.Malden21,E.Malinovski24,S.Mangano36,R.Maraˇc ek25,P.Marage4,J.Marks13,R.Marshall21,H.-U.Martyn1,J.Martyniak6,S.J.Maxfield18,D.Meer36,A.Mehta18,K.Meier14,A.B.Meyer11,H.Meyer33,J.Meyer10,S.Michine24,S.Mikocki6,stead18, S.Mohrdieck11,M.N.Mondragon7,F.Moreau27,A.Morozov8,J.V.Morris5,K.M¨u ller37, P.Mur´ın16,42,V.Nagovizin23,B.Naroska11,J.Naumann7,Th.Naumann35,P.R.Newman3, F.Niebergall11,C.Niebuhr10,O.Nix14,G.Nowak6,M.Nozicka30,B.Olivier10,J.E.Olsson10, D.Ozerov23,V.Panassik8,C.Pascaud26,G.D.Patel18,M.Peez22,E.Perez9,A.Petrukhin35, J.P.Phillips18,D.Pitzl10,R.P¨o schl26,I.Potachnikova12,B.Povh12,J.Rauschenberger11,P.Reimer29,B.Reisert25,C.Risler25,E.Rizvi3,P.Robmann37,R.Roosen4,A.Rostovtsev23, S.Rusakov24,K.Rybicki6,D.P.C.Sankey5,S.Sch¨a tzel13,J.Scheins10,F.-P.Schilling10,P.Schleper10,D.Schmidt33,D.Schmidt10,S.Schmidt25,S.Schmitt10,M.Schneider22,L.Schoeffel9,A.Sch¨o ning36,T.Sch¨o rner25,V.Schr¨o der10,H.-C.Schultz-Coulon7,C.Schwanenberger10,K.Sedl´a k29,F.Sefkow37,V.Shekelyan25,I.Sheviakov24,1L.N.Shtarkov24,Y.Sirois27,T.Sloan17,P.Smirnov24,Y.Soloviev24,D.South21,V.Spaskov8, A.Specka27,H.Spitzer11,R.Stamen7,B.Stella31,J.Stiewe14,I.Strauch10,U.Straumann37, S.Tchetchelnitski23,G.Thompson19,P.D.Thompson3,F.Tomasz14,D.Traynor19,P.Tru¨o l37, G.Tsipolitis10,38,I.Tsurin35,J.Turnau6,J.E.Turney19,E.Tzamariudaki25,A.Uraev23,M.Urban37,ik24,S.Valk´a r30,A.Valk´a rov´a30,C.Vall´e e22,P.Van Mechelen4,A.Vargas Trevino7,S.Vassiliev8,Y.Vazdik24,C.Veelken18,A.Vest1,A.Vichnevski8,K.Wacker7,J.Wagner10,R.Wallny37,B.Waugh21,G.Weber11,D.Wegener7,C.Werner13,N.Werner37, M.Wessels1,G.White17,S.Wiesand33,T.Wilksen10,M.Winde35,G.-G.Winter10,Ch.Wissing7,M.Wobisch10,E.-E.Woehrling3,E.W¨u nsch10,A.C.Wyatt21,J.ˇZ´aˇc ek30,J.Z´a leˇs´a k30,Z.Zhang26,A.Zhokin23,F.Zomer26,and M.zur Nedden251I.Physikalisches Institut der RWTH,Aachen,Germany a2III.Physikalisches Institut der RWTH,Aachen,Germany a3School of Physics and Space Research,University of Birmingham,Birmingham,UK b4Inter-University Institute for High Energies ULB-VUB,Brussels;Universiteit Antwerpen (UIA),Antwerpen;Belgium c5Rutherford Appleton Laboratory,Chilton,Didcot,UK b6Institute for Nuclear Physics,Cracow,Poland d7Institut f¨u r Physik,Universit¨a t Dortmund,Dortmund,Germany a8Joint Institute for Nuclear Research,Dubna,Russia9CEA,DSM/DAPNIA,CE-Saclay,Gif-sur-Yvette,France10DESY,Hamburg,Germany11Institut f¨u r Experimentalphysik,Universit¨a t Hamburg,Hamburg,Germany a12Max-Planck-Institut f¨u r Kernphysik,Heidelberg,Germany13Physikalisches Institut,Universit¨a t Heidelberg,Heidelberg,Germany a14Kirchhoff-Institut f¨u r Physik,Universit¨a t Heidelberg,Heidelberg,Germany a15Institut f¨u r experimentelle und Angewandte Physik,Universit¨a t Kiel,Kiel,Germany16Institute of Experimental Physics,Slovak Academy of Sciences,Koˇs ice,Slovak Republic e,f 17School of Physics and Chemistry,University of Lancaster,Lancaster,UK b18Department of Physics,University of Liverpool,Liverpool,UK b19Queen Mary and Westfield College,London,UK b20Physics Department,University of Lund,Lund,Sweden g21Physics Department,University of Manchester,Manchester,UK b22CPPM,CNRS/IN2P3-Univ Mediterranee,Marseille-France23Institute for Theoretical and Experimental Physics,Moscow,Russia l24Lebedev Physical Institute,Moscow,Russia e25Max-Planck-Institut f¨u r Physik,M¨u nchen,Germany26LAL,Universit´e de Paris-Sud,IN2P3-CNRS,Orsay,France27LPNHE,Ecole Polytechnique,IN2P3-CNRS,Palaiseau,France28LPNHE,Universit´e s Paris VI and VII,IN2P3-CNRS,Paris,France29Institute of Physics,Academy of Sciences of the Czech Republic,Praha,Czech Republic e,i 30Faculty of Mathematics and Physics,Charles University,Praha,Czech Republic e,i31Dipartimento di Fisica Universit`a di Roma Tre and INFN Roma3,Roma,Italy232Paul Scherrer Institut,Villigen,Switzerland33Fachbereich Physik,Bergische Universit¨a t Gesamthochschule Wuppertal,Wuppertal, Germany34Yerevan Physics Institute,Yerevan,Armenia35DESY,Zeuthen,Germany36Institut f¨u r Teilchenphysik,ETH,Z¨u rich,Switzerland j37Physik-Institut der Universit¨a t Z¨u rich,Z¨u rich,Switzerland j38Also at Physics Department,National Technical University,Zografou Campus,GR-15773 Athens,Greece39Also at Rechenzentrum,Bergische Universit¨a t Gesamthochschule Wuppertal,Germany40Also at Institut f¨u r Experimentelle Kernphysik,Universit¨a t Karlsruhe,Karlsruhe,Germany 41Also at Dept.Fis.Ap.CINVESTAV,M´e rida,Yucat´a n,M´e xico k42Also at University of P.J.ˇSaf´a rik,Koˇs ice,Slovak Republic43Also at CERN,Geneva,Switzerland44Also at Dept.Fis.CINVESTAV,M´e xico City,M´e xico ka Supported by the Bundesministerium f¨u r Bildung und Forschung,FRG,under contract numbers05H11GUA/1,05H11PAA/1,05H11PAB/9,05H11PEA/6,05H11VHA/7and 05H11VHB/5b Supported by the UK Particle Physics and Astronomy Research Council,and formerly by the UK Science and Engineering Research Councilc Supported by FNRS-FWO-Vlaanderen,IISN-IIKW and IWTd Partially Supported by the Polish State Committee for Scientific Research,grant no.2P0310318and SPUB/DESY/P03/DZ-1/99and by the German Bundesministerium f¨u r Bildung und Forschunge Supported by the Deutsche Forschungsgemeinschaftf Supported by VEGA SR grant no.2/1169/2001g Supported by the Swedish Natural Science Research Councili Supported by the Ministry of Education of the Czech Republic under the projectsINGO-LA116/2000and LN00A006,by GAUK grant no173/2000j Supported by the Swiss National Science Foundationk Supported by CONACyTl Partially Supported by Russian Foundation for Basic Research,grant no.00-15-965843Among the unexplained features of the Standard Model(SM)of particle physics is the exis-tence of three distinct generations of fermions and the hierarchy of their masses.One possible explanation for this is fermion substructure,with the constituents of the known fermions being strongly bound together by a new,as yet undiscovered force[1,2].A natural consequence of these models would be the existence of excited states of the known leptons and quarks.Assum-ing a compositeness scale in the TeV region,one would naively expect that the excited fermions have masses in the same energy region.However,the dynamics of the constituent level are un-known,so the lowest excited states could have masses of the order of only a few hundred GeV. Electron1-proton interactions at very high energies provide an excellent environment in which to search for excited fermions of thefirst generation.These excited electrons(e∗)could be singly produced through t-channelγand Z boson exchange.Their production cross-section and par-tial decay widths have been calculated using an effective Lagrangian[3,4]which depends on a compositeness mass scaleΛand on weight factors f and f′describing the relative coupling strengths of the excited lepton to the SU(2)L and U(1)Y gauge bosons,respectively.In this model the excited electron can decay to an electron or a neutrino via the radiation of a gauge boson(γ,W,Z)with branching ratios determined by the e∗mass and the coupling parameters f and f′.In most analyses[5–7]the assumption is made that these coupling parameters are of comparable strength and only the relationships f=+f′or f=−f′are considered.If a relationship between f and f′is assumed,the production cross-section and partial decay widths depend on two parameters only,namely the e∗mass and the ratio f/Λ.In this paper excited electrons are searched for in three samples of data taken by the H1 experiment from1994to2000with a total integrated luminosity of120pb−1.Thefirst sample consists of e+p data accumulated from1994to1997at positron and proton beam energies of27.5GeV and820GeV respectively,and corresponds to an integrated luminosity of37pb−1.A search for excited electrons using this sample of data has been previously published[8].The strategy for the selection of events has been modified from the procedures described in[8]to optimize the sensitivity to higher e∗masses.The two other samples were taken from1998 to2000with an electron or positron beam energy of27.5GeV and a proton beam energy of 920GeV.The integrated luminosities of the e−p and e+p samples are15pb−1and68pb−1, pared to previous H1results[8]the analysis presented here benefits from an increase in luminosity by a factor of more than three and an increase of the centre-of-mass energy from300GeV to318GeV.We search for all electroweak decays e∗→eγ,e∗→eZ and e∗→νW,considering the subsequent Z and W hadronic decay modes only.This leads tofinal states containing an electron and a photon,an electron and jets or jets with missing transverse energy induced by the neutrinos escaping from the detector.The Standard Model backgrounds which could mimic such signatures are neutral current Deep Inelastic Scattering(NC DIS),charged current Deep Inelastic Scattering(CC DIS),QED Compton scattering(or Wide Angle Bremsstrahlung W AB),photoproduction processes(γp)and lepton pair production via the two photon fusion process(γγ).The determination of the contribution of NC DIS processes is performed using two MonteCarlo samples which employ different models of QCD radiation.Thefirst was produced withthe DJANGO[9]event generator which includes QEDfirst order radiative corrections based onHERACLES[10].QCD radiation is implemented using ARIADNE[11]based on the ColourDipole Model[12].This sample,with an integrated luminosity of more than10times the exper-imental luminosity,is chosen to estimate the NC DIS contribution in the e∗→eγanalysis.The second sample was generated with the program RAPGAP[13],in which QEDfirst order radia-tive corrections are implemented as described above.RAPGAP includes the leading order QCDmatrix element and higher order radiative corrections are modelled by leading-log parton show-ers.This sample is used to determine potential NC DIS background in the e∗→νW֒→q¯q and e∗→eZ֒→q¯q searches,as RAPGAP describes better this particular phase space domain[8]. For both samples the parton densities in the proton are taken from the MRST[14]parametriza-tion which includes constraints from DIS measurements at HERA up to squared momentum transfers Q2=5000GeV2[15–18].Hadronisation is performed in the Lund string fragmenta-tion scheme using JETSET[19].The modelling of the CC DIS process is performed using the DJANGO program with MRST structure functions.While inelastic W AB is treated using the DJANGO generator,elastic and quasi-elastic W AB is simulated with the W ABGEN[20]event generator.Direct and resolvedγp processes including prompt photon production are generated with the PYTHIA[21]event generator.Finally theγγprocess is produced using the LPAIR generator[22].For the calculation of the e∗production cross-section and to determine the efficiencies,events have been generated with the COMPOS[23]generator based on the cross-section for-mulae given in reference[3]and the partial decay widths stated in reference[4].Initial stateradiation of a photon from the incoming electron is included.This generator uses the narrowwidth approximation(NW A)for the calculation of the production cross section and takes intoaccount the natural width for the e∗decay.For all values of f/Λrelevant to this analysis thisassumption is valid even at high e∗masses where the natural width of the e∗is of the order ofthe experimental resolution.To give an example,for M e∗=250GeV this resolution is equal to7GeV,10GeV,and12GeV for the eγ,eZ andνW decay modes,respectively.All Monte Carlo samples are subjected to a detailed simulation of the response of the H1detector.The detector components of the H1experiment[24]most relevant for this analysis arebriefly described in the following.Surrounding the interaction region is a system of drift andproportional chambers which covers the polar angle2range7◦<θ<176◦.The tracking sys-tem is surrounded by afinely segmented liquid argon(LAr)calorimeter covering the polar angle√range4◦<θ<154◦[25]with energy resolutions ofσE/E≃12%/E⊕2%for hadrons,obtained in test beam measurements[26,27].The tracking system and calorimeters are surrounded by a superconducting solenoid and an iron yoke instrumented with streamer tubes.Backgrounds not related to e+p or e−p collisions are rejected by requiring that a primary interaction vertex be reconstructed within±35cm of the nominal vertex position,by usingfilters based on the event topology and by requiring an event time which is consistent with the interaction time.Electromagnetic clusters are required to havemore than95%of their energy in the electromagnetic part of the calorimeter and to be isolated from other particles[28].They are further differentiated into electron and photon candidates using the tracking chambers.Jets with a minimum transverse momentum of5GeV are recon-structed from the hadronicfinal state using a cone algorithm adapted from the LUCELL schemein the JETSET package[19].Missing transverse energy(E misst )is reconstructed using the vec-tor sum of energy depositions in the calorimeter cells.The analysis presented in this paper is described extensively in[29].The e∗→eγchannel is characterized by two electromagnetic clusters in thefinal state. The main sources of background are the W AB process,NC DIS with photon radiation or a high energyπ0in a jet and the production of electron pairs viaγγfusion.Candidate events are selected with two electromagnetic clusters in the LAr calorimeter of transverse energy greater than20GeV and15GeV,respectively,and with a polar angle between0.1and2.2radians. The sum of the energies of the two clusters has to be greater than100GeV.If this sum is below 200GeV,the background is further suppressed by rejecting events with a total transverse energy of the two electromagnetic clusters lower than75GeV or with more than two tracks spatially associated to one of the clusters.The numbers of events passing the analysis cuts for the SM background processes and for the data in each of the three samples are given in Table1.About half of the background originates from NC DIS events with most of the remainder being due to W AB events.The efficiency for selecting the signal varies from85%for an e∗mass of150GeV to72%for an e∗mass of250GeV.As in all other channels the efficiencies are derived using samples of1000e∗events generated at different e∗masses.The various sources of systematic error are discussed later.Distributions of the invariant mass of the candidate electron-photon pairs of the three data samples together and for the SM expectation are shown in Fig.1a.Sample e−p920GeVChannel SM background SM background SM background e∗→eγ7.2±1.0±0.1 4.0±0.7±0.215.6±1.7±0.4 e∗→eZ֒→q¯q7.1±2.1±2.8 5.6±0.4±1.225.3±1.9±5.5 e∗→νW֒→q¯q 2.4±0.2±0.7 3.9±0.2±0.7 6.1±0.4±1.5 Table1:Number of candidate events observed in the three decay channels with the correspond-ing SM expectation and the uncertainties on the expectation(statistical and systematic error).The e∗→eZ֒→q¯q channel is characterized by an electromagnetic cluster with an associated track and two high transverse energy jets.The analysis for this channel uses a sample of events with at least two jets with a transverse energy above17GeV and16GeV,respectively,and an electron candidate with a transverse energy E e t>20GeV.These two jets and the electron must have polar angles smaller than2.2radians.Furthermore,to avoid possible double counting of events from the e∗→eγchannel,events with two electromagnetic clusters with transverse energies above10GeV and a total energy of the two clusters greater than100GeV are removed. The main SM contribution is NC DIS as photoproduction events do not yield a significant rate of electron candidates with large E e t.For20GeV<E e t<65GeV,a cut is made on the602468101214161820invariant mass (GeV)e v e n t s0510152025invariant mass (GeV)e v e n t s 012345678910invariant mass (GeV)e v e n t s Figure 1:Invariant mass spectra of candidate (a)eγpairs for the e ∗→eγanalysis,(b)elec-tron and two jets for the e ∗→eZ analysis and (c)neutrino and two jets for the e ∗→νW anal-ysis.Solid points correspond to the data and the histogram to the total expectation from different SM processes.electron polar angle.This ranges from θe <1.35for E e t =20GeV to θe <2.2radians for E e t =65GeV and depends linearly on E e t .The dijet invariant mass has to be in the range −15<M jj −M Z <7GeV .If there are more than two jets,the pair with invariant mass closest to the nominal Z boson mass is chosen as the Z candidate.The two jets chosen are ordered such that E jet 1t >E jet 2t .In many SM events the direction of jet 2is close to the proton direction.To ensure that this jet is well measured,an additional cut on its polar angle,θjet 2>0.2radians,7is applied if its transverse momentum is lower than30GeV.For an electron transverse energy 65GeV<E e t<85GeV two jets with an invariant mass M jj>M Z−30GeV are required. At very high transverse energy,E e t>85GeV,the contribution from NC DIS is very low and no further cuts on M jj are needed.The number of events which remain in the data after these cuts are summarized in Table1and compared with the expected SM contribution(mostly NC DIS events).The efficiency for selecting the signal varies from44%for an e∗mass of150GeV to 62%for an e∗mass of250GeV.Distributions of the invariant mass of the electron and the two jets are shown in Fig.1b for data and for the SM expectation.The e∗→νW֒→q¯q channel is characterized by two jets and missing transverse energy E miss t. The main background originates from CC DIS events with a moderate contribution from photo-production,whereas the NC DIS contribution is suppressed for large E misst .The analysis startsfrom a sample of events with at least two jets with transverse energies above17GeV and16GeV,missing transverse energy E misst >20GeV and no isolated electromagnetic cluster withtransverse energy above10GeV.The jets must have a polar angle below2.2radians.Jets in which the most energetic track enters the boundary region between two calorimeter modules and central jets(θ>0.5radians)are required to contain more than two tracks.This cut re-moves NC DIS events in which the scattered electron is misidentified as a jet.Only events with S=V apevents in a mass interval that varies with the width of the expected signal.At M e ∗=150GeV ,a width of the mass interval of 30GeV is chosen for the e ∗→eγdecay mode and 60GeV is chosen for the decay channels with two jets.Systematic uncertainties are taken into account as in [8].The limits on the product of the e ∗production cross-section and the decay branching ratio are shown in Fig.2.As stated in the introduction,most experiments give f/Λlimits under the assumptions f =+f ′and f =−f ′.The H1limits for each decay channel and after combi-nation of all decay channels are given as a function of the e ∗mass in Fig.3a,for the assumption f =+f ′.With this hypothesis the main contribution comes from the e ∗→eγchannel.The values of the limits for f/Λvary between 5×10−4and 10−2GeV −1for an e ∗mass ranging from 130GeV to 275GeV .These results improve significantly the previously published H1limits for e +p [8]collisions.The LEP experiments [5,6]and the ZEUS collaboration [7]have also reported on excited electron searches.Their limits are shown in Fig.3b.The LEP 2experiments have shown results in two mass domains.In direct searches for excited electrons limits up to a mass of about 200GeV are given.Above 200GeV their results are derived from indirect searches only.The H1limit extends the excluded region to higher masses than reached in previous direct searches.Figure 2:Upper limits at 95%confi-dence level on the product of the pro-duction cross-section σand the decaybranching ratio BR for excited elec-trons e ∗in the various electroweakdecay channels,e ∗→eγ(dashed line),e ∗→eZ ֒→q ¯q (dotted-dashedline)and e ∗→νW ֒→q ¯q (dotted line)as a function of the excited electronmass.The signal efficiencies used tocompute these limits have been deter-mined with events generated under theassumption f =+f ′.1010110e * mass (GeV)σ*B R (p b )More generally,limits on f/Λas a function of f ′/f are shown in Fig.4for three e ∗masses (150,200and 250GeV ).It is worth noting that excited electrons have vanishing electromag-netic coupling for f =−f ′.In this case the e ∗is produced through pure Z boson exchange.As a consequence the production cross-section for excited electrons at HERA is much smaller in the f =−f ′case than in the f =+f ′case.For e ∗masses between 150and 250GeV the ratio910101010e* mass (GeV)f /Λ (G e V -1)10101010e* mass (GeV)f /Λ (G e V -1)Figure 3:Exclusion limits on the coupling f/Λat 95%confidence level as a function of the mass of excited electrons with the assumption f =+f ′.(a)Limit for each decay channele ∗→eγ(dashed line),e ∗→eZ ֒→q ¯q (thick dotted-dashed line),e ∗→νW ֒→q ¯q (dotted line)and for the combination of the three channels (full line).It must be noted that a part of the data included in the present result were used to obtain the previous H1limit [8].(b)Comparison of this analysis with ZEUS results [7](dashed line)and LEP 2results on direct searches [5](dotted-dashed line)and on indirect searches [6](dotted line).of the cross-sections for f =+f ′and f =−f ′varies between 170and 900.For high e ∗masses and some values of the couplings,no limits are given because the natural width of the e ∗would become extremely large.In summary,a search for excited electron production was performed using all the e +p and e −p data accumulated by H1between 1994and 2000.No indication of a signal was found.New limits have been established as a function of the couplings and the excited electron mass for the conventional relationship between the couplings f =+f ′.The dependence of the f/Λlimit on the ratio f ′/f has been shown for the first time at HERA.The data presented here restrict excited electrons to higher mass values than has been possible previously in direct searches.We are grateful to the HERA machine group whose outstanding efforts have made and continue to make this experiment possible.We thank the engineers and technicians for their work in constructing and now maintaining the H1detector,our funding agencies for financial support,the DESY technical staff for continual assistance and the DESY directorate for the hospitality which they extend to the non-DESY members of the collaboration.10Figure 4:Exclusion lim-its on the coupling f/Λat 95%confidence level as a function of the ratio f ′/f for three different masses of the e ∗:150GeV (full line),200GeV (dotted line)and 250GeV (dashed line).10101010f //ff / Λ (G e V -1)References[1]H.Harari,Phys.Rep.104(1984)159.[2]F.Boudjema,A.Djouadi and J.L.Kneur,Z.Phys.C 57(1993)425.[3]K.Hagiwara,D.Zeppenfeld and S.Komamiya,Z.Phys.C 29(1985)115.[4]U.Baur,M.Spira and P.M.Zerwas,Phys.Rev.D 42(1990)815.[5]G.Abbiendi et al.[OPAL Collaboration],CERN-EP/2002-043,arXiv:hep-ex/0206061.Submitted to Phys.Lett.B [6]P.Abreu et al.[DELPHI Collaboration],Eur.Phys.J.C 8(1999)41[hep-ex/9811005].[7]S.Chekanov et al.[ZEUS Collaboration],DESY-01-132arXiv:hep-ex/0109018.[8]C.Adloff et al.,[H1Collaboration],Eur.Phys.J.C 17(2000)567[hep-ex/0007035].[9]G.A.Schuler and H.Spiesberger,in:Proceedings of Physics at HERA ,Hamburg 1991,V ol.3,pp.1419-1432.[10]A.Kwiatkowski,H.Spiesberger and H.J.M¨o hring,mun.69(1992)155.11[11]L.L¨o nnblad,mun.71(1992)15.[12]B.Andersson,G.Gustafson,L.L¨o nnblad and 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2021最全修订版从爱因斯坦到霍金的宇宙的作业全部答案下【使用方法】Ctrl+f快捷键调出查找对话框，在对话框内输入关键词或句子，即可快速定位答案，本答案分上下两部分，是为了不至于文件信息过于庞大，不好查找定位，好用记得评五星哦！1、第一个测万有引力常数的人是 (30.00分) 卡文迪什2、牛顿与莱布尼茨的矛盾源于：（） (30.00分) 微积分的发明人1、牛顿和莱布尼茨都是微积分独立的发现者。

(20.00分) 是2、海王星是理论预测后发现的，成功的证明了万有引力定律是正确的。

(20.00分) 是1、没有反作用力的是 (30.00分) 惯性力2、狭义相对论发表的时代，当时人们所知道的两种力是什么？ (30.00分) 万有引力和电磁力1、牛顿论证过绝对时间。

(20.00分) 否2、爱因斯坦提出绝对空间不存在。

(20.00分) 是1、首先提出等效原理的人是 (30.00分) 爱因斯坦2、关于单摆实验说法错误的是:（） (30.00分) T=2π(l/g)1、爱因斯坦认为引力场和惯性场是等效的，这就是等效原理，等效原理是广义相对论的基础。

(20.00分) 是2、力是维持运动的原因。

(20.00分) 否1、何时正式提出广义相对论的 (30.00分) 1915年2、被称为“几何之父”的是 (30.00分) 欧几里得1、等效原理是整个相对论的核心。

(20.00分) 是2、强等效原理认为，狭义相对论在其局域惯性参考系中完全成立。

(20.00分) 是1、广义相对论证明了:（） (30.00分) 以上都是2、在哪个几何体系中三角形三内角之和大于180度 (30.00分) 黎曼几何1、球面上两点之间最短的距离是大圆周。

(20.00分) 是2、在天文观测中看到的行星的轨道是封闭的椭圆。

(20.00分) 否1、离太阳最近的行星是 (30.00分) 水星2、下列说法错误的是？ (30.00分) 非匀速曲线运动属于惯性运动1、行星绕太阳运动是万有引力的作用。

宇宙大爆炸理论宇宙大爆炸理论，简称大爆炸理论（Big Bang Theory），是现代宇宙学中描述宇宙起源和演化的主流科学模型。

该理论提出，宇宙在约137亿年前由一个极热、极密的奇点状态开始膨胀和冷却，形成了今天的广阔宇宙。

宇宙的起源大爆炸理论的核心观点认为，宇宙起源于一个“奇点”，在这个奇点处，空间和时间失去了意义，物质和能量的密度无限大。

这个初始状态之后，宇宙经历了一个急剧的膨胀过程，即所谓的“宇宙膨胀”。

在这个过程中，宇宙从一个极端高温高密度的状态迅速扩张并冷却下来。

宇宙的演化随着宇宙的膨胀，温度逐渐降低，使得最初的基本粒子能够结合形成更复杂的原子核。

大约在大爆炸后的三分钟，宇宙冷却到足够低的温度，允许质子和中子结合形成氢和氦等轻元素。

这一时期被称为原初核合成。

随后数十亿年里，宇宙继续膨胀和冷却，引力作用使得物质逐渐聚集形成恒星和星系。

这些天体的形成和演化进一步推动了宇宙的多样化和复杂性。

宇宙的未来关于宇宙的未来，科学家们基于大爆炸理论提出了多种预测。

一种观点是宇宙将继续无限膨胀，最终达到热寂状态，即所有的物质和辐射都将均匀分布且温度极低。

另一种可能性是宇宙的膨胀最终会停止，并开始收缩，最终回到一个高密度状态，这被称为“大坍塌”。

大爆炸理论的证据大爆炸理论得到了多方面的科学证据支持：- 宇宙背景辐射：宇宙微波背景辐射是大爆炸留下的热辐射遗迹，其均匀性和微小的温度波动为宇宙早期状态提供了直接证据。

- 原初核合成：观测到的轻元素丰度与大爆炸理论预测的原初核合成过程相符合。

- 红移观测：遥远星系的光谱向红端移动，表明这些星系正在远离我们，这是宇宙膨胀的直接证据。

尽管大爆炸理论是目前解释宇宙起源和演化最为广泛接受的模型，但科学家们仍在探索更多细节，并寻找可能的新理论或修正以更好地理解我们的宇宙。