Search for the Dark Photon at Belle for 0.27 < m A < 3 GeV/c 2

Transcription

1 Sarch for th Dark Photon at Bll for.7 < m A < 3 GV/c Igal Jagl Univrsity of Hawai i at Mānoa for th Bll Collaboration QCD, Montpllir, 6 Juillt BELLE Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

2 Tabl of contnts Introduction Analysis stratgy 3 Background stimation Rsults Conclusion Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

3 )) Motivation rcntly strong intrst in dark sctor modls introduc a vctor boson A, and oftn a dark Higgs h by a Higgs mchanism can xplain th inconsistncis obsrvd in astrophysical data and dark mattr xprimnts positron xcss but no p xcss (PAMELA - figur lft) dirct dtction of dark mattr (DAMA/LIBRA - figur right) - )+ φ( + ) / (φ( + φ( Positron fraction.3... PAMELA Rsiduals (cpd/kg/kv) DAMA/NaI (.9 ton yr) (targt mass = 87.3 kg) -6 kv DAMA/LIBRA (.3 ton yr) (targt mass = 3.8 kg). Enrgy (GV) Tim (day) PAMELA - O. Adriani t al., Natur 8, (9) DAMA/LIBRA - R. Brnabi t al., Eur. Phys. J. C (8) 6: Igal Jagl (UH) Sarch for th Dark photon at Bll QCD 3 / 3

4 Prvious and nw sarchs startd in th lat 8 s rcntly fixd targt xprimnts hav bn approvd and/or commissiond at JLAB and MAMI this yar nw limit from BaBar plot blow shows astrophysical and cosmological constraints, and xprimntal limits BaBar rsults (B. Obrhof talk) (L = fb at Υ(S,3S,S)): + Ah ( AA) with A l + l (l= or µ) or hadrons α D ε - = 9 GV = 7 GV -6-7 = GV = 3 GV = GV m A (GV) α D ε - m A =. GV m A =. GV -6-7 m A = GV m A =. GV m A =.3 GV J. Jackl and A. Ringwald - arxiv:.39v -8 BaBar Collaboration - arxiv:.33 kintic mixing: χ or ǫ - dark photon: γ or A -9 - (GV) Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

5 Sarch for th Dark Photon and Dark Higgs at Bll + Ah AAA with A l + l (l= or µ) or hadrons B. Batll, M. Posplov, and A. Ritz arxiv: (9). Bll Exp. at KEK B-factory L = fb at Υ(S,S,3S,S,S) and continuum channls prsntd today µ + 3µ 3 A A h A A Kurokawa and E. Kikutani, NIM A 99, (3).7 < m A < 3 GV/c. < m h <.86 GV/c Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

6 Particl and final stat idntifications particl idntification plot shows Bll stup lctron ID: E-ECL/p-CDC µ ID: µ/k L masurmnts of pntration dpth and chargd track muon clustr matching K. Hanagaki t al, NIM A 8, 9 (). A. Abashian t al, NIM A 9, 69 (). Bll Collaboration, NIM A 79, 7 (). final stat idntification: 3l + 3l with l = or µ 6 chargd tracks 3 pairs of opposit charg 3/6 lptons to b idntifid, in ordr to maintain high fficincy Igal Jagl (UH) Sarch for th Dark photon at Bll QCD 6 / 3

7 Analysis stratgy Full rconstruction of xclusiv six-lpton final stats from + Ah AAA 3l + 3l (l = or µ) rquir nrgy and momntum consrvation calculat invariant mass for ach combinations of lptons consistnt with thr distinct A l + l kp combinations with thr masss (, m A and m3 A ) qual and m h > m A plots blow show signal Mont Carlo vnts surviving slction with m h = GV/c and m A =.9 GV/c Count [a.u.] 3 Count [a.u.] 6 Count [a.u.] m( ) [GV].. m(µ + µ - ) [GV].. m(π + π - ) [GV] Igal Jagl (UH) Sarch for th Dark photon at Bll QCD 7 / 3

8 Dtction fficincy + Ah AAA 3l + 3l + 3µ+ 3µ µ 6µ [%] [%] 6 mh [GV/c] 8 3 ] /c ] m A [GV /c V ] [G 3 8 =.3 GV/c =. GV/c =. GV/c =. GV/c = 3. GV/c mh /c V 6 mh [GV/c] [G /c ] m A [GV 6 Igal Jagl (UH) [%] =.3 GV/c =. GV/c =. GV/c =. GV/c = 3. GV/c mh [%] [%] [%] mh = GV/c mh = 3 GV/c mh = GV/c mh = 7 GV/c mh = 9 GV/c [GV/c] Sarch for th Dark photon at Bll mh = GV/c mh = 3 GV/c mh = GV/c mh = 7 GV/c mh = 9 GV/c [GV/c] QCD 8 / 3

9 ] ] ] ] Background stimation no ralistic background modl availabl => data drivn background stimation stimat background using sam sign vnts + Ah A(l + l )A(l + l + )A(l l ) ordr masss of lpton pairs m A > m A > m3 A and plot m A m3 A vs. m A µ + 3µ + - data opposit sign data sam sign - data opposit sign - 3µ + 3µ data sam sign [GV/c - m 3 A m A.3.. [GV/c - m 3 A m A.3.. [GV/c - m 3 A m A.3.. [GV/c - m 3 A m A.3.. m A [GV/c ] m A [GV/c ] m A [GV/c ] m A [GV/c ] slct rgion in m A and prdict background thr using sam sign => no count is found in th sam sign for muon final stat Igal Jagl (UH) Sarch for th Dark photon at Bll QCD 9 / 3

10 Background stimation sidband usd to normaliz sam sign to opposit sign background stimatd from th numbr of counts in th signal rgion of th sam sign distributions plot blow shows projction on m A 3 for m A =.9 GV/c count / MV/c 3 signal rgion + - data: 3 3, m =.9 GV/c A data: opposit sign data: sam sign norm. mc signal (opposit sign) sidband m A - m A [GV/c ] Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

11 Background stimation MC tst data: mc background opposit sign mc background sam sign 6 count count m A [GV/c ] m A [GV/c ] background stimation mthod vrifid succssfully with MC for xprimntal data, prdictd BG is > vnts for lctron final stat (s plot) vnt for muon final stat Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

12 Prliminary prdictd snsitivity assum numbr of vnts obsrvd = numbr of background uppr limit (9 % CL) dtrmind by Fldman-Cousins mthod µ + 3µ BF x σ [ab] Prliminary [GV/c ] m A = GV/c = 3 GV/c = GV/c = 7 GV/c = 9 GV/c BF x σ [ab] 6 [GV/c ] m A Prliminary = GV/c = 3 GV/c = GV/c = 7 GV/c = 9 GV/c => snsitivity scals narly linarly with intgratd luminosity Igal Jagl (UH) Sarch for th Dark photon at Bll QCD / 3

13 Conclusion Sarch for Dark photon and Dark Higgs in th mass rangs:.7 < m A < 3 GV/c. < m h <.86 GV/c From our control data sampl, w found that: background is stimatd to b small, implying snsitivity scals narly linarly with intgratd luminosity Rsults will b unblindd soon Thanks for your attntion Igal Jagl (UH) Sarch for th Dark photon at Bll QCD 3 / 3