New Physics on Rare and Doubly Cabibbo-Suppressed D Decays Chuan-Hung Chen Department of Physics, National Cheng-Kung U., Tainan, Taiwan pp7@08.06.07.ntu.tw In collaboration with C-Q Geng & S-H Nam Evidence for D0D0bar mixing & the implications New physics on D0   K+ New physics on lifetime difference in mixing Summary

New Physics on Rare and DCS D PPbar oscillations are important In the SM, FCNC induced from loop effects, box diagrams -- GIM mechanism to KKbar mixing, mK -- Heavy top-quark mass enhancement to BBbar mixing, mBq -- Except DDbar mixing, K  Kbar, Bq Bqbar are observed Due to these effects induced from loops, they are sensitive to the new physics, e.g. -- New CP violating phase on -- New Physics on New Physics on Rare and DCS D

Strong GIM cancellation, no heavy quark enhancement, How is D0D0bar mixing ? Strong GIM cancellation, no heavy quark enhancement, short-distance effects are negligible; long-distance effects are dominant CPV is negligible With SU(3)F limit, it vanishes Non-zero contributions are associated with SU(3) breaking, i.e. ( ms )n Heavy-quark effective theory with OPE Georgi (‘92), Bigi & Uraltsev (’01), Exclusive approach, Donoghue, Golowich, Holstein, Trampetic (’86); Petrov (’97); Falk, Grossman, Ligeti, Petrov (’02) with large uncertainity

Evidence for D-Dbar mixing observed by Babar, arXive: hep-ex/0703020, PRL98, 211802 (’07) & Belle, arXive: hep-ex/0703036, PRL98, 211803 (’07) With doubly Cabibbo-suppressed (DCS) decays D0 K+  Interference mixing

No signal for CP violation

New Physics on Rare and DCS D With singly Cabibbo-suppressed decays D0 K+ K No signal for CP violation New Physics on Rare and DCS D

New Physics on Rare and DCS D New physics on doubly Cabibbo-Suppressed (DCS) D0   K+ In the SM The definition of RD With SU(3) limit, New Physics on Rare and DCS D

New Physics on Rare and DCS D Factorization assumption & SU(3) breaking & Data for Factorization assumption Semileptonic decays P FP  K [ Gao, PLB645, 59 (‘07) ] Babar’s result in hep-ex/0703020 Indication of new physics New Physics on Rare and DCS D

New Physics on Rare and DCS D Left-right model on DCS D decay Left-right Model: SU(2)L  SU(2)R  U(1)X -- Two charged gauge bosons WL and WR -- Both will mix to be W1  WL -- Besides CKM matrix for left-handed quark, now we have similar flavor mixing effects for right-handed quark -- LR symmetric model, gL=gR, V(L)=V(R) , the contributions will be much smaller than those in the SM New Physics on Rare and DCS D

New Physics on Rare and DCS D Non-manifest LR model, Langacker & Sankar, PRD40,’89 London & Wyler, PLB232, ‘89 The relative size between SM and LR models all the hadronic effects are the same, if destructive interference happens New Physics on Rare and DCS D

New Physics on Rare and DCS D New physics (NP) on lifetime difference in DDbar mxing Golowich, Pakvasa, Petrov proposed that the lifetime difference could be sensitive to new physics. The idea is as follows: New Physics on Rare and DCS D

effective interactions with Operator product expansion (OPE) The leading term in the OPE is given

New Physics on Rare and DCS D In the SM, only O1 and O2 have the contributions SM result from short-distance is -- proportional to x3s, vanished in SU(3)F limit -- result of x3s displays the strong cancellation from GIM mechanism -- y(LO) ~ 108 New Physics on Rare and DCS D

New Physics on Rare and DCS D Non-manifest Left-right model on lifetime difference in D0 V(L)cs =O(1) V(R)us =O(1) New Physics on Rare and DCS D

New Physics on Rare and DCS D With leading OPE, the result of LR mixing effect With the values of parameters as: World average, A. Schwartz in FPCP New Physics on Rare and DCS D

New Physics on Rare and DCS D Summary Evidence of D-Dbar mixing implies y  O( 102 ) If CP violation in D-Dbar mixing is non-zero, it should be small Improved measurement on RD is necessary for new physics Left-right model has important effects on RD and lifetime difference in DDbar mixing New Physics on Rare and DCS D