1. Search for Excited Quark by HERA e-p Collider KUHEP colloquium 22 th Jun, 2009 Maeda Yosuke

2. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 2/total contents HERA e-p collider physics in HERA collider compositeness model H1 detector analysis summary HERA in myth

3. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 3/total HERA e-p collider DESY in Hamburg, Germany only e-p collider in the world 27.6GeV e + /e -, 920(820)GeV p (√s = 319(301)GeV) data taking 1992-2000(HERA-I) 2002-2007(HERA-II) integrated luminosity 475 pb -1 e - p : 184pb -1 e + p : 291pb -1 (35pb -1 with low energy) (Hadron Elektron Ring Anlage) Hamburg ★ e + /e - p HERA (6.4km) PETRA

4. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 4/total physics in HERA collider further search for internal structure with larger Q 2 –Deep Inelastic Scattering (DIS) model-dependent new physics –leptoquark –excited fermions (leptons, quarks) –single top production comparison with SM –W production (W  e, ) –isolated  event with missing P T –multi-lepton final states Q 2 = -q 2 = -(k-k’) 2 (Q 2 ~ 1/ ) x = Q 2 /(2p ･ q) y= (p ･ q)/(p ･ k)

5. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 5/total compositeness model Leptons and quarks are composite of more fundamental constituents. –explanation of 3 generations of quarks and leptons –excited fermions as a natural consequence of this model excited quarks –energy region : TeV, a few hundred GeV possible –interaction with ordinary fermions : –  : compositeness scale f, f’,f s : coupling parameter –only right-handed doublet F* R is allowed –In this analysis, assume f=f’, f s =0 SU(2)U(1)SU(3) C

6. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 6/total H1 detector concept –accurate lepton identification –high granularity and resolution for hadronic jet asymmetric design –  CM = 2.86 (in p direction) inner tracker EM / hadronic calorimeter  detector e + /e - p z y x interacion point

7. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 7/total inner tracking detectors measure momenta and angle of charged particle provide fast trigger signal central part –acceptance : 15 - 165 deg –silicon tracker –MWPC (CIP, COP, CIZ, COZ)  r  ~170  m,  z ~400  m –jet type chamber(CJC1, CJC2) –  (p T )/p T ~ 0.008p T [GeV] forward part –planar drift chambers, TRD, MWPC p e + /e - z 

8. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 8/total calorimeters Liquid Argon Calorimeters –acceptance : 4 - 154 deg –electromagnetic section (20-30)X 0 with 2.4mm-thick lead  EM (E)/E = 12%/√E[GeV] + 1% –hadronic section (5-8) with 19mm-thick stainless steal  had (E)/E = 50%/√E[GeV] + 2% –total 44354 channels SpaCal / sandwich (lead and scintillation fiber) –acceptance : 153 - 177.5 deg (measurement in the backward region) –divided into EM section and hadronic section 1.15T magnetic field parallel to z axis by superconducting coil 5.75m 6m SpaCal LAr calorimter

9. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 9/total other detectors tail catcher –measure leak of hadronic shower and penetrating  –ten 7.5cm-thick iron layer and 16 layers of streamer tube –5 - 15mm spatial resolution luminosity measurement –use Bethe-Heitler process of small angle bremsstrahlung (The cross section is well calculated) –detectors : electron tagger (ET) @ z=-33.4m, photon detector (PD) @ z=-102.9m (segmented crystal Cerenkov counter) tracking SpaCal FNC PLUG VLQ z e + /e - p

10. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 10/total photos of H1 detectors LAr calorimeter tracking chamber (CJC1, CJC2) silicon tracker (FDT) SpaCal example of event display

11. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 11/total analysis decay mode to search here : –q*  q , q*  qW/Z  qqq, q*  qW  ql, q*  qZ  qll (l=e,  ) trigger : EM or hadronic energy deposit in LAr or missing transverse energy (rate : 10-20MHz) require reconstructed z vertex to be within 35cm from the nominal interaction point find e, ,  and hadron jet candidates –e,  : compact and iolated shower in EM section of calorimeters (further require small hadronic energy deposit, to be isolated from any other jet and association with inner tracks) –m : inner track and signal in muon detectors (less than 5GeV deposit in a cylinder) –hadron jet : energy deposit in calorimeters except above (associated with inner tracks)

12. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 12/total search for q*  q  signal : one isolated EM cluster with high p T and one jet with high p T background : SM radiative NC DIS and prompt photon cut condition –5 deg 35GeV –5 deg 20GeV –Bjorken scaling value x=Q 2 /M >0.1 (exclude photoproduction events) –reject EM energy deposit of >10GeV in LAr (NC DIS rejection) →44 events remained (SM prediction : 46 +/- 8 events)

13. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 13/total search for q*  qqq signal : 3 high p T jets (q*  qW  qqq, q*  qZ  qqq) background : multi-jet photoproduction and NC DIS cut condition –at least 3 jets with 5 deg <  jet < 120 deg –p T >50GeV, 30GeV, 15GeV –invariant mass of 2 jets with low p T close to W or Z mass (70GeV~100GeV) →341 events remained (SM prediction : 326 +/- 78 events)

14. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 14/total search for q*  qe, q  signal : 1 lepton, 1 jet and missing p T background : W production (SM DIS, photoproduction and lepton pair production can also be background by mismeasurement) cut condition () for q*  q  –missing p T > 25GeV –p T e,  >10GeV, 5 deg 1 (R=√(  2 +  2 ),  : rapidity) –for e, V ap /V a >0.25 (to reject photoproduction event) –p T jet >20(15)GeV, 5 deg 25GeV for  jet <60deg in q*  q  ) –invariant mass of e(m) and missing 55GeV ~ 100GeV (for e), >40GeV (for  ) q*  q  5 event (SM:4.4+/-0.7) q*  qe 6 event (SM:6.0+/-0.8)

15. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 15/total search for q*  qee, q  signal : 2 high p T leptons and 1 jet background : SM lepton pair creation cut condition () for q*  q  –5 deg 20(15)GeV, 10GeV –for e, associated good quality track in 5 deg <  e < 35 deg –invariant mass : M Z +/- 7GeV (for e), >50GeV (for  ) –5 deg 20GeV →No data remained for both e and . (SM prediction : 0.44 +/- 0.08 for e, 0.87 +/- 0.11 for  )

16. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 16/total setting upper limits f=f’, f s =0 –branching ratio of q*(95% C.L.) –q* mass (assume f/  ~ 1/M q* )  exclude <252GeV –limit on f/   exclude wider region than the result of DELPHI at LEP effect of non-zero f s –large SM dijet background –Mq*<190 –complement result with CDF

17. 22 th Jun, 2009KUHEP colloquium Search for Excited Quark by HERA ep Collider 17/total summary Excited quarks are searched for using the full data of e-p collision by H1 detector at HERA. (L=475fb -1 ) H1 is designed as a multi-purpose detector, and focused on good lepton identification and energy resolution by using LAr. The decay modes of excited quark q*  q , q*  qqq, q*  ql, q*  qll (=q,  ) are examined. Results are in good agreement with SM prediction, and there is no evidence of q* existence with the assumption of f=f’ and f s =0 With the assumption above, M q* <252GeV is excluded.