Tau SUSY analysis Taikan Suehara ICEPP The Univ

Tau & SUSY analysis Taikan Suehara ICEPP, The Univ. of Tokyo Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 1

BG suppression cuts results • Backgrounds are suppressed to negligible level. • Signal efficiency is ~23%, quite low but… – Most cut events in first 2 cuts are with hard-photons – Practical signal efficiency is considered ~75% Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 2

Decay modes in Apol analysis t -> enn • Branching ratio: 17. 8% • 3 body decay; pol. info is smeared t -> mnn • Branching ratio: 17. 4% • 3 body decay; same as enn mode t -> pn • Branching ratio: 10. 9% • Pol. can be directly observed by p distribution t -> rn, r -> pp • Branching ratio: 25. 2% • Pol. of r can also be obtained by p distribution in r-rest frame (pol. of r is connected to pol. of t) t -> a 1 n, a 1 -> ppp • Branching ratio: 9. 3% • Currently not used because statistics is low Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 3

t -> pn selection results Selection performance between geometries (look at the 2 nd row from the bottom) • Efficiency: not so different • Purity: LDC’ > GLD’ > J 4 LDC – t -> rn mode (decay 2 p is mis-reconstructed as single) might be the reason (larger is better) – LDC’ has advantage due to high CAL granularity. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 4

Apol calculation (pn mode) Statistical error is almost the same for all geometries Value shifts are larger in GLD’/J 4 LDC due to the lower purity. Stat error in 500 fb-1 Values obtained by signal-only events! Value shift due to the mode BG Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 5

r -> pn selection results • 3 rd row from bottom: used as “no p 0 mass cut”. • 2 nd row from bottom: used as “p 0 mass cut”. – Events with single neutral are survived with this cut. • Most bottom row: used as “tight p 0 mass cut”. – Events with single neutral are eliminated with this cut. • Clear difference by geometries: LDC’s the best, bigger is better in Jupiter’s. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 6

Apol calculation (rn mode) Statistical errors are larger in GLD’/LDC, esp. with mp 0 cut. Value shift is smaller than pn mode, negligible with mp 0 cut. Stat error in 500 fb-1 Values obtained by signal-only events! Value shift due to the mode BG Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 7

イベント数 • Singal : 2. 3 M / 500 fb-1 – 可能？ – Back to backをpreselectしてもよい (半分弱になる) • Bhabha : いまのpreselectionで 20000/0. 2 fb-1 – 5 M / 50 fb-1 • ggtautau: いまのpreselectionならおそらく 500 fb-1可能 – ~0. 1 M / 500 fb-1 • 他のモードはfull scanをやろうとしている Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 8

SM separation cuts • # of SM events becomes comparable to chargino after these cuts. • No difference between geometries in this stage. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 9

Cut statistics (2) chargino neutralino • BG separation is efficient (see W/Z mass cut rows) • Slightly better BG separation performance in GLD but almost within statistical fluctuations. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 10

Chargino mass fit results • Fitting function: 3 rd polynomial (4 param) (center) / 0 (edge) convoluted with a Gaussian with s as linear function of energy (2 param) edge position: 2 param, total # of parameters = 8 • Cheat fitting: 1. fix edge positions at true value, fit other 6 parameters. 2. fix those 6 parameters and fit edge positions. • No significant difference between geometries. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 11

Neutralino mass fit results • Fitting function: Error function (left) x Complementary error function (right) Width of left and right is the same, # of parameters = 4 • Cheat fitting: Same as chargino • J 4 LDC gives slightly larger width than other two. Corresponding fitting error is enhanced. Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 12

イベント数 • SUSY: 500 fb-1可能 (100 kくらい) • WW background – 10000 fb – 4 -jet 標準SMでは 20 fb-1 – Preselectして増やすかどうか考える • 4 -jet + neutrino – まだ考えてない • こちらも全BGスキャン Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 13

今日何を話しますか？ Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 14

Backup Taikan Suehara, ILD opt/soft asia meeting, 1 Oct. 2008 page 15