Future B Physics Program at KEK KEKB upgrade

Future B Physics Program at KEK (KEKB upgrade strategy) - KEK’s Roadmap - BNM 2008 (24 -Jan, Atami) Y. Sakai, KEK based on slides by Masa Yamauchi, KEK 1

Outline n Introduction: KEKB and Belle n Next program of quark flavour physics n KEK’s five year roadmap n KEKB upgrade plan → Onishi’s talk n Detector issues n Organization of new experimental group n Summary 2

KEKB and Belle 3

Belle Detector Cherenkov detector n=1. 015~1. 030 SC solenoid 1. 5 T 3. 5 Ge. V e+ EM calorimeter (Cs. I(Tl)) TOF counter 8 Ge. V e- Central drift chamber He(50%)+C 2 H 6(50%) Si vertex detector m / KL detector 4

The Belle Collaboration BINP Chiba U. U. of Cincinnati Ewha Womans U. Fu-Jen Catholic U. U. of Giessen Gyeongsang Nat’l U. Hanyang U. U. of Hawaii Hiroshima Tech. IHEP, Beijing IHEP, Moscow IHEP, Vienna ITEP Kanagawa U. KEK Korea U. Krakow Inst. of Nucl. Phys. Kyoto U. Kyungpook Nat’l U. EPF Lausanne Jozef Stefan Inst. / U. of Ljubljana / U. of Maribor U. of Melbourne Nagoya U. Nara Women’s U. National Central U. National Taiwan U. National United U. Nihon Dental College Niigata U. Nova Gorica Osaka U. Osaka City U. Panjab U. Peking U. Princeton U. Riken Saga U. USTC Seoul National U. Shinshu U. Sungkyunkwan U. U. of Sydney Tata Institute Toho U. Tohoku U. Tohuku Gakuin U. U. of Tokyo Inst. of Tech. Tokyo Metropolitan U. Tokyo U. of Agri. and Tech. INFN Torino Toyama Nat’l College VPI Yonsei U. 14 countries, 55 institutes, ~400 collaborators 5

Scientific Achievements of B Factories (1) Observation of CPV in the B meson system ACP(t) = G(B f. CP; t) - G(B f. CP; t) = Af cos. Dmt + Sf sin. Dmt G(B f. CP; t) + G(B f. CP; t) Belle, July 05 B 0 J/y. KS Belle, July 05 Af ~ 0 Sf = 0. 652± 0. 039± 0. 020 Consistent with Ba. Bar’s meas. 6

Achievements of the B Factories Quantitative confirmation of the KM model Belle, July 05 B 0 J/y. KS Discovery of CP violation in BB system Af ~ 0 Sf = 0. 652± 0. 039± 0. 020 Belle, July 05 Violation of CP symmetry ! 7

Other highlights Many new resonances AFB in Bg. K*l+l. X(3872) Belle, 2005 D 0 -D 0 mixing Evidence for Bg Z(4430) SM Bgdg transition Bg. D* and more… 8

Another important achievement Asymmetric e+e- collider with L > 1034 n Success of KEKB and PEP-II enabled us to design a new e+e- B factory with much higher Lpeak. 9

What is next with flavour physics? n If new physics at O(1)Te. V… – It is natural to assume that the effects are seen in B/D/t decays. – Flavour structure of new physics? – CP violation in new physics? – These studies will be useful to identify mechanism of SUSY breaking, if NP=SUSY. n Otherwise… – Search for deviations from SM in flavor physics will be one of the best ways to find new physics. 10

KEKB upgrade n Asymmetric energy e+e- collider at ECM=m( (4 S)) to be realized by upgrading the existing KEKB collider. n Super-high luminosity 2 1035/cm 2/sec 2 10 9 BB per yr. (1 st stage: >x 10) 2 10 9 t+t- per yr. Belle with improved rate immunity Higher beam current, more RF, smaller by* and crab crossing L = 2 1035/cm 2/sec final target ~8 1035/cm 2/sec (smooth transition: 50 ab-1) http: //belle. kek. jp/superb/loi 11

Physics at upgraded KEKB New source of CP violation LFV decays New source of flavor mixing Precision test of KM scheme SUSY breaking mechanism Charm physics New resonances, D 0 D 0 mixing… Super-high statistics measurements: a. S, sin 2 q. W, etc. 12

SUSY flavour physics: mass matrix of squark and slepton will be determined by their direct production at the energy frontier and flavour physics measurements. Quark flavor changing processes Diagonal Off-diagonal LHC/ILC SUSY mass spectrum Lepton flavor violation 13 Y. Okada, Nov. 2007

Searches for new sources of quark mixing and CP violation CP asymmetries of penguin dominated B decays Deviation from SM Present upper limits New source of CP violation Measurements at upgraded KEKB （ ab-1 ） Reach of present B factories Reach of upgraded KEKB Relevant to baryogenesis? 14

A possible hint for NP: b→sqq Theory : tends to positive shifts Smaller than bgccs in 7 of 9 modes 15

Precise measurements of t decays Upper limits t->mg New Physics predictions Branching Fraction LFV violating t decay? Integ. Lum. （ ab-1 ） Reach of B factories m->eg t->eg T. Goto et al. , 2007 16 Upgraded KEKB

B decays with more than one n Interactions of H± B n Bgtn decays B H+/W+ Belle, 2006 400 fb-1 e- e+ Υ B t + p D full reconstruction 0. 2~0. 3% for B+ 10 ab-1 Provides a unique method to measure b-H±-u and b-H±-c coupling strength. Search region with Bgtn decays 17

B decays into invisible particles? Light dark matter? _ B K(*)nn [or cc] Model prediction Heavy darm matter is being searched for in direct detection experiments. Light dark matter can be Searched for in the upgraded KEKB. 18

Search for right handed interaction Precision of the measurement Left-right summetry in new physics? CP violation in B KSp 0 g Present exp. precision Sizable CP asymmetry is expected in B 0 Xg decay, if right-handed interaction exists in new physics. U-KEKB Reach of upgraded. KEKB SM 19 T. Goto et al. , 2007

New resonances found at Belle/Ba. Bar Y(4660) Z(4430) Y(4008) Ds. J(2860) Ds. J(2700) Xcx(3090) X(3940), Y(3940) Sc* baryon triplet D 0 *0 & D 1 *0 Y(4320) cc 2’ More than 10 new resonances have been found at B factories Among them X（3872） and Z（4430） are considered to be “exotic” states. Y(4260) X(3872) Ds. J(2317/2460) hc’ & e+e- cccc More and more exotic states will be Observed by the upgraded KEKB. 20

Identification of SUSY breaking scenario Pattern of deviations from the Standard Model SUSY models Observables m. SUGRA SU(5)SUSY GUT + R Bdunitarity D m(Bs) e B->f. Ks B->Msg Y. Okada b->sg indirect CP - - - + ++ ++ ++ ++ (degenerate) SU(5)SUSY GUT + R (nondegenerate) U(2) Flavor symmetry ++: Large, +: sizable, -: small 21

Strong competitors 22

Comparison with LHCb e+e- is advantageous in… LHCb is advantageous in… CPV in B→f. KS, h’KS, … CPV in B→J/y. KS CPV in B→KSp 0 g Most of B decays not including n or g B→Knn, tn, D(*)tn Inclusive b→smm, see t→mg and other LFV D 0 D 0 mixing Time dependent measurements of BS B(s, d)→mm Bc and bottomed baryons These are complementary to each other !! 23

Roadmap -HEPEnergy Frontier ILC R&D Construction Experiment LHC Flavor Physics at Luminosity/Intensity Frontier , K, , . . . at J-PARC b, c, , . . . with upgraded- KEKB/Belle • According to the JAHEP community’s master plan, – Highest priority is given to ILC – Before ILC, promote flavor physics at KEKB and J-PARC • Action before the ILC approval – ILC R&D – Completion/commissioning of J-PARC • Considering the world competition, it is urgent to improve neutrino intensity – Continuation of KEKB/Belle with upgrade 24

KEK Web page (5 Year Plan) 25

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KEK Roadmap : KEKB First 3 years: shutdown • Replace beam pipe (with ante-chamber) • Upgrade interaction region fundamental part • Upgrade ground level RF facility • Improve crab cavities Last 2 years: operation & improvements • Installation of Damping Ring • Installation of additional RF • Reinforcement of cooling facility Onishi’s talk 1 st goal: 2 x 1035 cm-2 sec-1 smooth transition feasible to 8 x 1035 cm-2 sec-1(50 ab-1) 27

KEK Roadmap: Belle Upgrade in 3 years shutdown Issues 4 Higher background ( 20) - radiation damage and occupancy - fake hits and pile-up noise in the EM 4 Higher event rate ( 10) - higher rate trigger, DAQ and computing 4 Require special features - low p m identification f smm recon. eff. - hermeticity f n “reconstruction” Possible solution: 4 Replace inner layers of the vertex detector with a silicon striplet detector. 4 Replace inner part of the central tracker with a silicon strip detector. 4 Better particle identification device 4 Replace endcap calorimeter by pure Cs. I. 4 Faster readout electronics and computing system. 28

Belle detector upgrade Faster calorimeter with Wave sampling and pure Cs. I crystal KL/m detection with scintillator and new generation photon sensors New Dead time free readout and high speed computing systems Super particle identifier with precise Cherenkov device Background tolerant super small cell tracking detector Si vertex detector with high background tolerance New ideas are welcomed !

New experimental group n It will be practical to build new detector by upgrading existing Belle. n However, the experimental group will be a new group, not an extension of the present Belle collaboration. n New participants are all welcomed and have equal opportunities to work on detector construction and physics. n It is welcomed to join the new group, but not Belle. n Interim Steering Committee is being formed. First meeting is scheduled March 2008, inviting potential new collaborators.

2007 10 2008 1 4 7 2009 10 1 4 7 2010 10 1 4 Experiment at KEKB 7 2011 10 1 4 7 2012 10 1 4 KEKB/Belle upgrade TDR Detector Study Report (March 08) Final detector design (April 09) 2007 10 11 2008 12 1 2 3 4 5 6 7 2009 8 9 Detector proposals BNM Pre kick-off (January 08) meeting (19, 20 March 08) 10 11 12 1 2 3 4 Internal review Kick-off meeting (3, 4 July 08) Meeting plan Actions to invite new collaborators One-day general meeting and an IB meeting at every BGM 31

Summary n KEKB/Belle and PEP-II/Ba. Bar have been running very successfully, and brought important scientific and technical achievements. n Next generation e+e- B factory with L~1036 will be very useful to study the new sources of flavor mixing and CP violation. – – – n n Search for new CPV in bgs transition Very precise test of CKM scheme Search for lepton flavor violating t decays Studies of H± interactions with fermions Very precise measurements of a. S(@10 Ge. V), sin 2 q. W(@10 Ge. V)… KEK Roadmap includes KEKB upgrade. KEKB machine upgrade plan Onishi’s talk Detector upgrade necessary to improve BKG/rate immunity. New collaboration to be formed soon. 32

Roadmap: comment Our final goal of the integrated luminosity is 50/ab in the new experiment at the upgraded KEKB. However, we did not include the full upgrade of the machine in the KEK's roadmap, due to the financial constraint in the lab. We will upgrade the fundamental part of the accelerator in the first three years, followed by incremental installation of the RF systems over several years to increase the beam current and the luminosity. The initial goal, 10/ab, will be achieved in the five years of operation after resuming the experiment. It should be noted that the plan up to this point is included in the KEK's roadmap. Then, considering the results of this experiment and LHC as well as progress of ILC and others carefully, we will decide if we propose further installation of the RF system to achieve the final goal, 50/ab, in the next five years. 33

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Precision test of KM scheme M. Pierini CKM 2006 35

Search for new flavor mixing l+ lg, Z 0 b quark ? s quark Possible observables: : Probe the flavor changing process with the “EW probe”. This measurement is especially sensitive to new physics such as SUSY, heavy Higgs and extra dim. Theoretical predictions for l +l - forward-backward charge asymmetry for SM and SUSY model with various parameter sets. 4 Ratio of branching fractions 4 Branching fraction 4 CP asymmetry 4 q 2 distribution 4 Isospin asymmetry 4 Triple product correlation 4 Forward backward asymmetry 4 Forward backward CP asymmetry The F/B asymmetry is a consequence of g-Z 0 interference. 36

Search for new CP phases In general, new physics contains new sources of flavor mixing and CP violation. 4 In SUSY models, for example, SUSY particles contribute to the b s transition, and their CP phases change CPV observed in B f. K, h’K etc. U-KEKB SM SUSY contribution In general, if SUSY is present, the s-quark mixing matrix contains complex phases just as in the Kobayashi-Maskawa matrix. T. Goto et al. , 37 2007

Background & TRG rate in future x 20 Bkg KEK Super B B Luminosity (1034 cm-2 sec-1) x 10 Bkg HER curr. (A) LER curr. (A) vacuum (10 - KEKB Bkg SVD CDC PID / ECL KLM ~1. 7 ~50 1. 2 1. 6 ~1. 5 4. 1 9. 4 5 - x 20 7 Pa) Bkg Shynchrotoron radiation increase Beam-gas scattering (inc. intra-beam scattering) Radiative Bhabha TRG rate