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Emmanuelle PEREZ DESY & CEA-Saclay

14th International Workshop on Deep Inelastic Scattering. Recent Results from the H1 Experiment. Emmanuelle PEREZ DESY & CEA-Saclay. High Q 2 DIS : inclusive measurements searches for new physics, jets Hadronic Final State in low Q 2 NC DIS Diffraction: vector mesons

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Emmanuelle PEREZ DESY & CEA-Saclay

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  1. 14th International Workshop on Deep Inelastic Scattering Recent Results from the H1 Experiment Emmanuelle PEREZ DESY & CEA-Saclay • High Q2 DIS: inclusive measurements • searches for new physics, jets • Hadronic Final State in low Q2 NC DIS • Diffraction: vector mesons • inclusive diffraction • final states • Rare processes 20 April 2006 DIS ’06, Tsukuba

  2. Polarised leptons 05 99-00 98-99 03-04 94-97 H1 datasets HERA I : ~ 130 pb-1 - mainly e+ p data - several analyses getting finalised on HERA I data HERA II (since 2003) : - 50 pb-1 of e+p - 100 pb-1 of e-p - polarised leptons, P typically 30 -40 % - analysed so far: what benefits from polar, stat, and new capabilities of the H1 detector Analyses presented here : up to 280 pb-1 DIS’ 06, 20 / 04 / 06

  3. Charged Current DIS CC(e,SM) ~ (1  Pe) • e+ p : first publication • on HERAII data • (PLB 634 (2006) 173) e- p • e- p : prelim. measurements with the • full available 05 stat. 69 pb-1 HERA I (syst.) typically 4%, (stat.) from 2% to 8% 30 pb-1 27 pb-1 21 pb-1 e+ p Extrapolations to Pe =  1 consistent with no WR First H1 diff. CC x-section measurements on HERA II data : agreement with H1PDF2000 DIS’ 06, 20 / 04 / 06

  4. Polarised Neutral Current DIS d/dQ2 measured for NC DIS in HERA II polarised data. At high Q2 ( Z interference ) : RH / LH > 1 for e+ p, RH / LH < 1 for e- p e+ p RH / LH Expected polarisation dependence confirmed although with limited precision. e- p RH / LH DIS’ 06, 20 / 04 / 06

  5. Measurement of xF3 ~ ~ Correct for polar. effect : (e-) - (e+) gives access to the non-singlet SF xF3 ~ x ( q – q ) - Combine HERA I (15 pb-1 e-, 100 pb-1 e+) with HERA II (120 pb-1 e-, 50 pb-1 e+) • stat. errors reduced by 20-30 % • Neglect pure Z contribution • (small) and correct for • propagator terms  little • dependence on Q2 • Test the x dependence of valence quarks. ~ 2uv + dv - (if s = s ) DIS’ 06, 20 / 04 / 06

  6. , e e * , Z, W W q q High Q2 NC DIS, several jets H1 Preliminary Jets in high Q2 NC DIS: constraints on * • Excited fermions: signature of a new scale of matter • Can be singly produced in DIS • Excited neutrinos would be produced much more • copiously in e- p than in e+ p f/ • Analysis of 2005 e- data (114 pb-1) All decays analysed (with W/Z  jets) For large M(*) : *  eW dominates No resonance in any of the 3 channels Most stringent constraints so far ! For f/ = 1 /M M > 188 GeV DIS’ 06, 20 / 04 / 06

  7. +0.0046 S(MZ) = 0.1197  0.0016 (exp.) (th.) -0.0048 Jets in High Q2 NC DIS : S measurements 61 pb-1 Inclusive jets in Breit frame Large statistics ! Q2 > 150 GeV2 Fit S(MZ) in each (Q2, ET) bin using NLO calculations. Combined fit leads to: Exp. error ~ 1.3 % Reduced by a factor of 2 w.r.t. 2001 analysis (reduced had. scale uncertainty) but large theo. error (scale uncertainties) DIS’ 06, 20 / 04 / 06

  8. HFS in high Q2 DIS: fragmentation For tracks in the current region of the Breit frame: Norm. charged particle momentum distrib. xp = p / (Q/2) 45 pb-1 (2000) Increased stat. (60k evts) High Q2, <Q> up to ELEP Full xp range 1/Nevents dn/dxp Clear scaling violations observed Q increasing xp Well described by RAPGAP (frag. model tuned to ee data) Good agreement with ee data (a bit softer ?)  quark fragmentation universality Comparison with NLO calculations show sensitivity to  frag. functions.

  9. 0 /  separation in low Q2 DIS e *  e  and q *  q  Measurement of prompt photon in DIS: Q2 > 4 GeV2, ET > 3 GeV, -1.2 <  < 1.8 Extended range ( x 10) w.r.t. previous HERA meas. isolated  with z = E / Ejet > 0.9 Variables based on the shower shape combined into a likelihood discriminator HERA I data, 71 pb-1 MC describes the rate of isolated 0 in the HFS ! e *  e  dominates q *  q  dominates -1.2 <  < -0.6 0.2 <  < 0.9 Cross sections well described by recent O(3) QED calculation First H1 measurement of prompt  in DIS DIS’ 06, 20 / 04 / 06

  10. Jets in low Q2 DIS : QCD at low x Study jets in low x DIS, where DGLAP might be unsufficient to describe g radiation • forward jets : theory & models • too low at low xBj hep-ex/0508055 • search for gluon radiation • unordered in kT in 3-jet events 99-00 data, 44 pb-1 • 3 jets with PT* > 4 GeV 10-4 < x < 10-2, 5 < Q2 < 80 GeV2 ~ 40 000 events Comparison with MC programs: - DGLAP based MC : normalisation too low (60%) shapes are not described - Color Dipole Model (unordered kT): OK Only MC with kT-unordered gluon radiation describes the data. DIS’ 06, 20 / 04 / 06

  11. 3-Jets in low Q2 DIS : QCD at low x Comparison with NLO O(S3): NLO < data at lowest x, largest  • Look separately in 2 subsamples: - 1 forward + 2 central jets - 2 forward + 1 central jets Discrepancy mainly in the “2 forward jets” sample. Huge improvement LO  NLO : O(S3) includes the “first kT-unordered” radiation Strong hints that, in this region of phase space, the effect of kT-unordered gluon radiations is important. DIS’ 06, 20 / 04 / 06

  12. Further BFKL insights: VM at large t At large t : photoproduction of VM described in pQCD by : - LO : exchange of two gluons - beyond LO : exchange of a gluon ladder Different predictions for the t-dependence and for the helicity structure of the interaction. Probability for T  L t 2g Analysis of   , 20 pb-1 (2000) e detected in low-angle electron tagger (trigger…) BFKL • t-dependence • spin density matrix elements hep-ex/0603038 better described by gluon ladder exchange. BFKL interference 2g But no model describes all the features of the data. DIS’ 06, 20 / 04 / 06

  13. + 0.005 - 0.014 0 = 1.106  0.003 + 0.019 - 0.062 ’ = 0.156  0.027  photoproduction at low t VM production with no hard scale expected to be described by Regge phenom. Old H1 meas. (1994 data): ~ 300 events (tagged p) H1 2005 HERA II : Fast Track Trigger trigger on tracks down to PT of 100 MeV ~ 300 K events !  New measurement on 2005 data : d/dt (W) for elastic and p-dissociation - Extraction within a single experiment - No use of low W data (exchange of other trajectories) Assuming (t) = 0 + ’ t : OK with DL ??? ’ much lower than the slope of the soft Pom !!! DIS’ 06, 20 / 04 / 06

  14. The Pomeron Trajectory in diffractive DIS Select diffractive DIS events by tagging the leading proton (carrying a fraction 1-xPom of incoming p momentum) in our Forward Proton Spectrometer (FPS) xPom • Allows t measurement • Study d/dt ~ eBt in bins of xPom p Regge approach: B = B0 – 2 ’ ln(xPom) Low xPom : B ~ 6 GeV-2 ~ 3000 events 28 pb-1 (99-00) Small shrinkage favoured Final results ’ = 0.06 +0.19-0.06 GeV-2 Factorisation of the t-dependence from (Q2, x) P(0) also extracted from the xPom dependence Increased Reggeon contrib. ( = x / xPom) DIS’ 06, 20 / 04 / 06

  15. Diffractive DIS with Large Rapidity Gaps Our final results LRG (max method) xPom = 0.003 =0.017 (x = 5 10-5 ) H1 LRG • Large kinematic domain covered • Precise measurements : syst. typically 5%, • normalisation ~ 6%, stat. 5 – 20% Comparison with FPS data : Amount of p-diss in LRG meas. shows no kinem. dependence on Q2, xPom,  =0.67 (x = 0.002) LRG/FPS = 1.23  0.16 DIS’ 06, 20 / 04 / 06

  16. Diffractive DIS with Large Rapidity Gaps  dependence: driven by quark diff. PDFs xPom = 0.003 Diffractive cross-section remains sizeable up to largest  values. xPom = 0.03 Reggeon contribution important at high xPom and low  DIS’ 06, 20 / 04 / 06

  17. QCD analysis of LRG  : DPDFs (“Proton vertex factorisation” assumed) No kinem. dependence of P(0) observed. IP + Reggeon contributions 2 / ndf = 158 / 183 MRS ansatz: A zB (1-z)C A,B and C necessary for (z) Gluon poorly constrained : Similarly good fits obtained with Ag and Cg, and with Ag only (Fit B) Fitted Reggeon normalisation in very good agreement with that obtained in the FPS data. Gluon carries ~ 70% of the momentum of the colorless exchange DIS’ 06, 20 / 04 / 06

  18. Factorisation in diff. DIS : jets Dijet events with a LRG  2700 evts ( x 6 w.r.t. previous H1 analysis : 50 pb-1 (99-00 data), extended kinematic range ) Overall good agreement with NLO predictions. Fit Fit B Confirmation that factorisation holds. Log10(xPom) Preference for “Fit B” Previous analysis Fit B Differences show up in variables most sensitive to the gluon density at high z xPom DIS’ 06, 20 / 04 / 06

  19. Using jets to better constrain DPDFs Combined fit of F2D and dijet data : 2/ndf (total) = 196 / 217 2/ndf (dijets) = 27 / 36 2/ndf (F2D) = 169 / 190 Both datasets well described by the combined fit. Combined fit ~ close to Fit B; dijets provide important constraints on high z gluon ! DIS’ 06, 20 / 04 / 06

  20. Factorisation in diff. DIS: charm • Use D* to identify c quarks  prel. meas. 50 pb-1 (99-00) • New measurement: exploit the long lifetime of • charmed hadrons : • Use track impact parameters meas. with the SiDet; • inclusive method  no large extrapolations S =  / ()  measurement of F2Dcc in bins in (xPom, Q2, ) Cf H1, EPJ. C45 (2006) 23 Good agreement with the D* x-sections (extrapolation factor ~ 2.5) Q2 = 35 GeV2 xPom = 0.018 Good agreement with NLO QCD using the DPDFs obtained from F2D (complementary to jets since lower PT lower z) Charm production accounts to ~ 20% of the diff. x-section (cf. inclusive case) DIS’ 06, 20 / 04 / 06

  21. F2D on 99-04 data Medium Q2 : 12 < Q2 < 90 GeV2 • 97 : 10 pb-1 • 99-00 : 35 pb-1 • 2004 : 35 pb-1 (fwd det. a bit  ) 99-04: Low Q2 & large  not yet Measurements confirm 97 data with reduced stat. errors Q2 DIS’ 06, 20 / 04 / 06

  22. MX increases Extraction of the diff. component: max vs MX Non-diff exp. fall-off Comparison H1 / ZEUS :  methods used  Try the “MX” method on 99-00 data Result of subtraction Limited lever-arm due to acceptance: MX reco’ed with LAr calorimeter ( < 3.4) • ZEUS: good E meas. up to  = 5 • in contrast, H1 has good taggers • up to   7.5 No bias found with the MX method in the (limited) range where H1 can apply it. DIS’ 06, 20 / 04 / 06

  23. Often not detected Small Q2 Rare processes at HERA : +- production Final states: e, ejet, jet, jetjet Maximal S/B when restricting to elastic production i.e. DIS & p backgrounds mainly from diffractive processes Use of neural networks to separate -jets from hadronic jets Bckgd from diff. dijets at zpom 1 signal hep-ex/0604022 In kinem. range 20o <  < 160o, PT > 2 GeV:  = 13.6  4.4  3.7 pb First observation of  pair production at HERA DIS’ 06, 20 / 04 / 06

  24. Search for W   hep-ex/0604022 Search for W   in HERA-I data completed Isolated  + PT,miss PTX • Effi. x Acc. ~ 8% : • 1-prong had. decays • only (~ 49%) • limited  range • (W prod)  1 pb Combining with prelim. results on HERA-II data : H1 prelim., 278 pb-1 A few events observed at PTX > 25 GeV in HERA II data – but limited statistics… DIS’ 06, 20 / 04 / 06

  25. W Production (e & ) W  e,  : isolated e,  + PT,miss + had. System (PTX) Positrons Electrons Effi. x Acc. ~ 30% Wide  range High W purity (87% at high PTX) excess not seen in e- p ! In e+ p : 3.4  effect… Our best chance for a discovery !

  26. 275 pb-1 H1 Prelim., HERA I+II 2l + 3l Multilepton events at HERA Events with  2 leptons in final state. Mainly produced via  Cross-section when both leptons are central, PT1 > 10 GeV, PT2 > 5 GeV :  < 1 pb H1 data 94-00 : excess of 2e+3e events at high M12 = mass of two highest PT e The H1 evts are not consistent with e  H++ (e)  ee(e) hep-ex/0604027 Significant constraints set on H++ coupling to e- and to e- Analysis extended to include 03-05 data Extended to other 2l & 3l topologies : Now ee, , e, eee, e are considered • no new 2e / 3e evt at M12 > 100 GeV • (but one high mass 3e event …) • one e evt at M > 100 GeV, one at Me > 100 GeV Altogether, at  PT > 100 GeV : Nobs = 4, Nexp = 1.1  0.2 All high mass evts in e+p … DIS’ 06, 20 / 04 / 06 E. Perez

  27. Concluding remarks • Finalisation of analyses on HERA I data: Diffraction: finalisation of analysis using the Forward Proton Spectrometer and of inclusive Large Rapidity Gap analysis Combined fit F2D + dijet data Further tests of factorisation (also D* in photoproduction) Also on hadronic final states and heavy flavor physics • New preliminary results on HERA II data: • *, F2D,  with Fast Track Trigger, also DVCS measurement • First combinations of HERA I & HERA II : xF3 measurement, searches We are entering a new phase of analyses aiming to the highest precision. DIS’ 06, 20 / 04 / 06

  28. H1 talks at DIS’06 Andrei NikiforovNeutral current studies at HERA II Jacek TurnauMeasurement of Event Shape Variables in DIS at HERA Katja KruegerPhotoproduction of di-jets with High Transverse Momenta at HERA Steve MaxfieldInclusive Jet Production in DIS at high Q2 at HERA Dima OzerovSearch for a Narrow Baryonic Resonance Decaying to K0_s p(pbar) Carsten SchmitzPrompt Photons in DIS Christoph WernerParton Dynamics in DIS multi jet events at small x Magnus HanssonDi-jets at low x and low Q2 Dan TraynorScaled Charged Particles Momentum Distributions at high Q2 Lars FinkeProduction of charm and beauty dijets at HERA Ying-Chun ZhuElastic J/Psi production at HERA Biljana AntunovicCharged current studies at HERA II Paul LaycockF2bb/F2cc at HERA Benoit RolandDVCS at HERA Jan OlssonRho Photoproduction at HERA Carl GwilliamRho production at large t at HERA Paul NewmanF2D3 and F2D4 measurements Emmanuel SauvanF2D3 new analysis at medium Q2 Olaf BehnkeDiffractive D* and F2D(cc) Matthias MozerDiffractive di-jets and combined fits Max KleinFL measurements and low energy running Dave South New H1 results on Isolated leptons and Missing PT at HERA Claude Vallee Multi-lepton events and search for H++ at HERA Christian HelebrantLeptoquark searches at HERA Stefania Xella Tau lepton production at HERA Cristinel Diaconu Search for excited neutrinos at HERA Christiane Risler Forward Jet Production in Deep Inelastic Scattering at HERA

  29. Backup & Divers DIS’ 06, 20 / 04 / 06

  30. Azimuthal correlations in dijet low Q2 events Alternative test of DGLAP in low x DIS: Study the  between the two jets closest in  to the e. Large kT of gluon  broadening of  64 pb-1 (99-00) W.r.t. previous analysis : much larger stat, improved resolution on the HFS measurement. - O(S2) unsufficient to describe the data. • O(S3) much better, still low at small  • (but large scale errors on the prediction) • Normalising to the x-section integrated • over  < 170 deg. amplifies the differences • (cf H1, Eur. Phys. J. C33 (2004) 477) i.e. hints that O(S3) not enough DIS’ 06, 20 / 04 / 06

  31. QCD analysis of LRG  No kinem. dependence of P(0) observed. Scaling violations at large  are driven by q  qg and not g splittings. i.e. inclusive diff. DIS not much sensitive to the Dgluon at large Fractional momentum ! DIS’ 06, 20 / 04 / 06

  32. Factorisation in diff. p: D* Diffractive photoproduction of jets: breaking of factorisation both for the resolved  ( ~ expected) and direct  (unexpected ?) processes.  Investigate diff. p of D* (direct process largely dominates) p events : e detected in low angle electron tagger (trigger..)  limited statistics ~ 50 pb-1 D*+ D0 +slow  K- + +slow (+c.c.) Comparison with NLO calculation (FMNR) : Good agreement within the (large) errors. No evidence for a breaking of factorisation in diff. p of D* mesons. DIS’ 06, 20 / 04 / 06

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