KEK-PR0C--95-11 Proceedings JP9607178 of the Fifth Workshop on Japan Linear Collider (JLC) Kavvatabi, Miyagi, Japan, February 16 - 17, 1995 Positrons 10 GeV 1.54 GeV S-band S-band Pre-Accelerator Injector 500 GeV 10-30 GeV X-band Linac S-band Linac for Positron Generation 1.54 GeV Positron Damping Ring NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS, KEK KEK Proceedings 95-11 December 1995 A/H Proceedings of the Fifth Workshop on Japan Linear Collider (JLC) Kawatabi, Miyagi, Japan, February 16 - 17, 1995 Editor: Y. Kurihara National Laboratory for High Energy Physics, 1995 KEK Reports are available from: Technical Information & Library National Laboratory for High Energy Physics 1-1 Oho, Tsukuba-shi Ibaraki-ken, 305 JAPAN Phone: 0298-64-1171 Telex: 3652-534 (Domestic) (0)3652-534 (International) Fax: 0298-64-4604 Cable: KEK OHO E-mail: LIBRARY@JPNKEKVX (Bitnet Address) [email protected] (Internet Address) Contents Physics at LEPII T. Tsukamoto 1 Present Status of 1.54 GeV ATF Linac S.Takeda 12 Button-type beam-position monitor for the ATF damping ring F. Hinode 28 Recent progress on cathode development and gun development at Nagoya and KEK M.Tawada 31 Development of polarized e+ beams for future linear colliders M. Chiba 38 The LASER beams with very long focal depth for photon-photon collider K. Matsukado 78 An interactive version of GRACE and catalogue of e+e- interactions as its application S.Kawabata 92 The GRACE system for SUSY processes M. Jimbo 98 Search for dynamical symmetry breaking physics by using top quark T. Asaka 108 Status of R&D for the vertex detector Y. Sugimoto 121 Progress report of calorimeter subgroup Y. Fujii 123 I NEXT PAGE(S) | left BLANK JLC '95 2 J! 1 6 5 (*) I. %$ 9:00-10:05 (KEK) MM W$- (&] EE5OO 7-^~>3 7 7*^ BB|*J (KEK) 2. WKH io:2o-ii;4O Vs=500GeV"C r ^ - # 7 - fi JL A & ^ ? e+e'->w+w" Kiifc £ £ &t & Vector Resonance KEK Search for Dynamical Symmetry Breaking by Using Top Quark yy ii 7 4 y—tr cOHiggs 7> ^ r-Y - 3. Wk 1:00-2:40 The GRACE System for SUSY Processes GRACE tCATALOGUE KEK JUS Event Generator for Wpain Production KEK ^M Photon Photon Collider Plil^)^C'^, iS^^C IR Issues KEK 4. jDiltf (1)2:50-4:10 ^S JIIM KEK KEK Klystron Modulator <D Wk KEK 5. JMtf (2) 4:20-5:20 Damping Ring i: Vacuum Chamber O|r1^§ KEK Damping Ring ffl Beam Position Monitor CO fn\%fe KEK Alignment ^#i 60 ?l^t KEK ft 1*1 ISffloltT-^t'-f #> KEK Compton — in — 2 M 1 7 B i. iffilfeS 9:00-10:00 JM.& Baft *a#7-?->3 7yMR]tfT KEK }\\ffl VTX Progress Report KEK CAL Progress Report KEK 2. Wm 10:15-11:45 Jig BT£ The Measurment of Weak Boson Properties at Linear and Hadron Collider R. Szalapski Probing the Weak Boson Sector in eY -» zy and 7e-» ze S. Y. Choi Consequences of New Interactions in the EW Boson Sector ftHil&W Higgs Production and Decay in an Extended Supersymmetric Standard Model KEK ||T Precision SUSY Studies at Future Linear Collider KEK SJ'J^, S-quark correction to e+e- w+w-@JLC MJZ HJM = 3. Uffl8frWi ?-U<D$l& 11:45-13:05 Mg M# (^) 3. M 4. Physics at LEP II Toshio Tsukamoto Department of Physics, Saga University, Saga-shi, Saga, 840 Japan Abstract After the successful running as a Z factory, LEP machine is to be upgraded to the second phase with doubling the beam energy in order to operate beyond the W+W~ threshold. Here an overview is presented of the physics topics at LEP II. 1 Introduction It has passed 6 years since the first commissioning of LEP in 1989. The machine performance has been improved year by year and more than 15 millions of Z° events are now recorded. The Standard Model is checked out precisely and systematically through a variety of processes. One of the most fundamental parameter in the Standard Model Mz is measured down to 2 x 10~5 accuracy. The measurements of total width as well as partial decay widths of Z° enable one to determine the number of light neutrino species to be 3 with 5 per mil precision and put strong constraints for the invisible light particles at the same time. The couplings to Z° is derived with ever-improving accuracy using the forward-backward asymmetry of leptons and the r polarization measurements and the lepton universality is found to stand. So far, the Electroweak Standard Model is strongly supported by these LEP measurements. LEP II program will push it further to clarify the gauge structure in the Electroweak Stan- dard Model by studying W boson properties and gauge couplings. On the other hand, LEP has been the highest energy e+e~ collider and provided a unique opportunity in searching for new particles. Direct searches extensively done at LEP I resulted in no evidence at the moment. However, good news is that the properties of unknown particles are estimated indirectly based on the precision measurements of Z°. In fact, LEP I data is sensitive to the electroweak radiative correction and the mass of top has been evaluated assuming the Standard Model (Mtop ~ 176 ± 10t\l GeV). Recent observation of top quark at Fermilab [1] gave consistent values of Miop = 176 ± 8 ± 10 GeV (CDF) and Mtop = 199±" ± 22 GeV (D0) with similar accuracy to the indirect estimation from the Z° measurements. For the yet-unknown Higgs boson, one can also perform a global fit to MH using all the existing electroweak data. The situation is, however, quite different from Mtop case. Only very weak logarithmic dependence to the radiative correction is given for MJJ while Mtop has quadratic dependence. Although the minimum of x2 value indicates lower Higgs mass around 100 GeV [2], it is still premature to extract MH value with meaningful precision. Discussion on the grand unification of running coupling constants implies that the super- symmetric energy scale should be below 1 TeV assuming the minimal SUSY extension of the Standard Model [3]. If this minimal SUSY scenario is true, supersymmetric particles has to be found below 1 TeV. Especially, the lightest Higgs boson predicted by the minimal SUSY can exist below 130 GeV [4] which might be discovered in the near future. Now the LEP is going to increase its energy and one can expect a number of physics outputs from the new phase of LEP. Major physics issues at LEP II can be summarized as follows. • Study of W properties and gauge couplings through e+e~ —> W+W~ as a W pair pro- duction machine • Search for Higgs bosons and new particles as well as new exotic phenomena as a highest energy e+e~ machine 2 Machine upgrades for LEP II To double the beam energy, higher power of RF system has to be installed, because of the significant energy loss due to synchrotron radiation which goes as the 4th power of the energy. It is approved that 176 super conducting cavities are added to the existing 120 copper cavities in the next phase of LEP. With this configuration, a maximum energy of y^ = 175GeV can be accessible. The mass of W can be measured precisely in this first upgrade. Further increased energy is, however, apparently preferable in searching for new particles and new phenomena. By removing half of copper cavities and installing 70 more super conducting cavities, the energy can be increased up to 190 GeV. From the physics point of view, this second upgrades might be crucial since there could be a gap in the Higgs discovery range between LEP and LHC. The scenarios for further upgrades are now under discussion. It is said that 205 GeV can in principle be achieved without civil engineering [5] but is unlikely to be realized at the moment. Target integrated luminosity for LEP II is 500pb-1 within 3 years. Despite of great success of 8 bunch operation by the pretzel scheme started in 1992, it was found to be difficult to achieve the goal. Bunch train schemes were investigated instead. The result of the studies under LEP I operation looks very promising. For 1995 run, LEP will be operated at Z° energy with 4 trains in 4 bunches. Due to the total current limitation, 4 trains in 2 or 3 bunches will be adopted for LEP II. 3 Mw measurement Current available value for Mw from hadron colliders is 80.26 ± 0.16 GeV [6] which agrees quite well with the indirect estimation by LEP data: 80.32 ± 0.06 GeV. The masses of the W and Z are related by the formula: TO M2 L W V2GF(l - M& I Ml) (1 - Ar) where Ar is the radiative correction to the boson mass. Thus the precise measurement of gives another strict check of the radiative correction. The size of the radiative correction is changed by Mtop and MH- Unknown parameter MH can be evaluated indirectly, once Mtop is determined with a good precision by Tevatron. Figure 1 shows the relation between Mw and Mtop for different MJJ. Also shown in the figure are the Mw value from hadron colliders and Mtop from Tevatron measurements [1], Further improvement both on Mw and on Miop measurements could constrain the value of MH- Together with precise results from Z° measurements, the self- consistency of the Standard Model can be checked in a model independent way. Three independent methods are being investigated to measure the mass of W at LEP II [7]: • Direct mass reconstruction of the final state • Excitation curve near WW threshold • End point of lepton energy decayed from W As a result of the Monte Carlo studies, the first one is the most promising in terms of accuracy.