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Search for Excited Quark by HERA e-p Collider

Search for Excited Quark by HERA e-p Collider. KUHEP colloquium 22 th Jun, 2009 Maeda Yosuke. contents. HERA e-p collider physics in HERA collider compositeness model H1 detector analysis summary. HERA in myth. HERA e-p collider. Hamburg. ★. (Hadron Elektron Ring Anlage).

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Search for Excited Quark by HERA e-p Collider

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  1. Search for Excited Quarkby HERA e-p Collider KUHEP colloquium22th Jun, 2009 Maeda Yosuke

  2. contents • HERA e-p collider • physics in HERA collider • compositeness model • H1 detector • analysis • summary HERA in myth KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  3. HERA e-p collider Hamburg ★ (Hadron Elektron Ring Anlage) • 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 luminosity475 pb-1 e-p : 184pb-1 e+p : 291pb-1(35pb-1 with low energy) p HERA (6.4km) e+/e- PETRA KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  4. physics in HERA collider • further search for internal structure with larger Q2 • Deep Inelastic Scattering (DIS) • model-dependent new physics • leptoquark • excited fermions (leptons, quarks) • single top production • comparison with SM • W production (We,n) • isolated t event with missing PT • multi-lepton final states Q2 = -q2 = -(k-k’)2 (Q2 ~ 1/l) x = Q2/(2p･q) y=(p･q)/(p･k) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  5. 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 : • L : compositeness scalef, f’,fs : coupling parameter • only right-handed doublet F*R is allowed • In this analysis, assume f=f’, fs=0 SU(2) U(1) SU(3)C KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  6. H1 detector y • concept • accurate lepton identification • high granularity and resolutionfor hadronic jet • asymmetric design • gCM = 2.86 (in p direction) • inner tracker • EM / hadroniccalorimeter • m detector z x p interacion point e+/e- KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  7. 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)srf~170mm, sz~400mm • jet type chamber(CJC1, CJC2) • s(pT)/pT ~ 0.008pT[GeV] • forward part • planar drift chambers, TRD, MWPC q z p e+/e- KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  8. 6m calorimeters • Liquid Argon Calorimeters • acceptance : 4 - 154 deg • electromagnetic section • (20-30)X0 with 2.4mm-thick lead • sEM(E)/E = 12%/√E[GeV] + 1% • hadronic section • (5-8)l with 19mm-thick stainless steal • shad(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 LAr calorimter SpaCal 5.75m 1.15T magnetic field parallel to z axis by superconducting coil KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  9. other detectors SpaCal FNC tracking • tail catcher • measure leak of hadronic showerand penetrating m • ten 7.5cm-thick iron layer and16 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) PLUG p e+/e- VLQ z KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  10. photos of H1 detectors silicon tracker(FDT) SpaCal LAr calorimeter example of event display tracking chamber(CJC1, CJC2) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  11. analysis • decay mode to search here : • q*qg, q*qW/Zqqq, q*qWqln, q*qZqll (l=e,m) • 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, g, m and hadron jet candidates • e,g : 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) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  12. search for q*qg • signal : one isolated EM cluster with high pT and one jet with high pT • background : SM radiative NC DIS and prompt photon • cut condition • 5 deg < qg < 90 deg, pTg>35GeV • 5 deg < qjet < 80 deg, pTjet>20GeV • Bjorken scaling value x=Q2/Mn>0.1(exclude photoproduction events) • reject EM energy deposit of >10GeV in LAr(NC DIS rejection) →44 events remained (SM prediction : 46 +/- 8 events) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

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

  14. search for q*qen, qmn • signal : 1 lepton, 1 jet and missing pT • background : W production(SM DIS, photoproduction and lepton pair production can also be background by mismeasurement) • cut condition () for q*qmn • missing pT > 25GeV • pTe,m>10GeV, 5 deg < qe,m < 100 deg,e cluster must be isolated from any other jetwith R>1 (R=√(Dh2+Df2), h : rapidity) • for e, Vap/Va>0.25 (to reject photoproduction event) • pTjet>20(15)GeV, 5 deg < qjet < 100(160) deg (pTjet>25GeV for qjet<60deg in q*qmn) • invariant mass of e(m) and missing n 55GeV ~ 100GeV (for e), >40GeV (for m) q*qen6 event(SM:6.0+/-0.8) q*qmn5 event(SM:4.4+/-0.7) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

  15. search for q*qee, qmm • signal : 2 high pT leptons and 1 jet • background : SM lepton pair creation • cut condition () for q*qmm • 5 deg < qe < 100(160) deg, pTe>20(15)GeV, 10GeV • for e, associated good quality track in 5 deg < qe < 35 deg • invariant mass : MZ +/- 7GeV (for e), >50GeV (for m) • 5 deg < qjet < 100 deg, pTjet>20GeV →No data remained for both e and m.(SM prediction : 0.44 +/- 0.08 for e, 0.87 +/- 0.11 for m) KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

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

  17. 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*qg, q*qqq, q*qln, q*qll (=q,m) 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 fs=0 • With the assumption above, Mq*<252GeV is excluded. KUHEP colloquiumSearch for Excited Quark by HERA ep Collider

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