1. Diffractive studies and forward physics at CMS Marta Ruspa, Univ. Piemonte Orientale-Novara & INFN-Torino XIV International Workshop on Deep Inelastic Scattering April 20-24, 2006, Tsukuba (Japan)

2. 2 DIS06, 20-24/04/06, M. Ruspa CMS detectors along beam line: Cal with |  | ≤ 3, HF with 3 ≤|  | ≤ 5 Castor calorimeter, behind T2 with 5.2 ≤|  | ≤ 6.5 Beam Scintillation counters BSC Zero-degree calorimeter ZDC Forward detectors at CMS CMS IP T1/T2, Castor, BSC ZDC RPs@150m RPs@220m 420m TOTEM detectors: T1 (CSC) in CMS endcaps T2 (GEM) in shielding behind HF T1 + T2: 3 ≤ |  | ≤ 6.8 Roman pots with Si detectors on 2 sides at up to 220 m Possible addition: FP420 Unprecedented rapidity coverage at a hadron collider

3. 3 DIS06, 20-24/04/06, M. Ruspa Roman pot acceptance High  * (1540m) @ 10 28 - 10 29 cm -2 s -1 : 90% of all diffractive protons are seen in TOTEM RPs Low  * (0.5 m) - nominal LHC beam optics @ 10 33 - 10 34 cm -2 s -1 : 220 m: 0.02 <  < 0.2 420 m: 0.002 <  < 0.02 Standard optics  * = 0.5 m assumed from now on TOTEM FP420 see J. Whitmore’s talk X L = 1 -  : longitudinal momentum loss Unprecedented ξ coverage at a hadron collider

4. 4 DIS06, 20-24/04/06, M. Ruspa CMS/TOTEM diffractive physics program TOTEM and CMS pursue a common diffractive and forward physics program to be described in a common document A wealth of results already available [see HERA-LHC Workshop proceedings] Thanks to TOTEM people and to all contributors! The results presented in the following do not depend on the specific hardware implementation of the T1 and T2 detectors or of the roman pots; they hold for any tracker system with the T1, T2 rapidity coverage in conjunction with RPs at 220 m and 420 m from the IP.

5. 5 DIS06, 20-24/04/06, M. Ruspa The accessible physics is a function of the integrated luminosity 2 gluon exchange with vacuum quantum numbers “Pomeron” X Double Pomeron exchange: X Single diffraction: p p  p X p p  p X p X Y Double diffraction: p p  X Y

6. 6 DIS06, 20-24/04/06, M. Ruspa Low lumi Rapidity gap selection possible HF, Castor, BSCs, T1, T2 Proton tag selection optional RPs at 220m and 420 m Diffraction is about 1/4 of  tot High cross section processes “Soft” diffraction Interesting for start-up running Important for understanding pile-up Low lumi High lumi Map to diffractive/forward physics in CMS

7. 7 DIS06, 20-24/04/06, M. Ruspa Number of pileup events per bunch crossing = = Lumi* cross section * bunch time width * total lhc bunches / filled bunches = = 10 34 cm -2 s -1 * 10 4 (cm^ 2 /m^ 2 ) * 10 -28 (m 2 / b) * 110 mb * 10 -3 (b/mb) * 25 (ns) * 10 -9 (s/ns) * 3564 / 2808  35  1x10 32  0  1x10 33  3.5  2x10 33  7 Pile-up: numbers! 1 mb = 100 events/s @ 10 29 cm -2 s -1 PHOJET: ALL PROCESSES 110 mb NONDIF.INELASTIC 51 mb ELASTIC 33 mb DOUBLE POMERON 1.95 mb SINGLE DIFFR.(1) 7.66 mb SINGLE DIFFR.(2) 7.52 mb DOUBLE DIFFRACT. 9.3 mb Number of pileup events per bunch crossing = = Lumi* cross section * bunch time width * total lhc bunches / filled bunches = = 10 34 cm -2 s -1 * 10 4 (cm^ 2 /m^ 2 ) * 10 -28 (m 2 / b) * 51 mb * 10 -3 (b/mb) * 25 (ns) * 10 -9 (s/ns) * 3564 / 2808  17 This number is valid in the central detector region, but must be corrected for the elastic and diffractive cross section in the forward region! Selection of diffractive events with rapidity gap only possible at luminosities below 10 33 cm -2 s -1, where event pile-up is absent

8. 8 DIS06, 20-24/04/06, M. Ruspa Low lumi Rapidity gap selection possible HF, Castor, BSCs, T1, T2 Proton tag selection optional RPs at 220m and 420 m Diffraction is about 1/4 of  tot High cross section processes “Soft” diffraction Interesting for start-up running Important for understanding pile-up QCD: SD and DPE production of vector bosons, heavy quarks, high E T jets Diff PDFs and generalized PDFs Low-x structure of the proton High-density regime γ γ and γp interactions (QED) Forward energy flow - input to cosmics shower simulation Low lumi High lumi Map to diffractive/forward physics in CMS

9. 9 DIS06, 20-24/04/06, M. Ruspa Low lumi Rapidity gap selection possible HF, Castor, BSCs, T1, T2 Proton tag selection optional RPs at 220m and 420 m Diffraction is about 1/4 of  tot High cross section processes “Soft” diffraction Interesting for start-up running Important for understanding pile-up QCD: SD and DPE production of vector bosons, heavy quarks, high E T jets Diff PDFs and generalized PDFs Low-x structure of the proton High-density regime γ γ and γp interactions (QED) Forward energy flow - input to cosmics shower simulation Low lumi High lumi Map to diffractive/forward physics in CMS High lumi No Rapidity gap selection possible Proton tag selection indispensable RPs at 220 m and 420 m Central exclusive production Discovery physics: Light SM Higgs MSSM Higgs

10. 10 DIS06, 20-24/04/06, M. Ruspa Selection rules result in the central system being (to good approx) J PC = 0 ++ I.e. a particle produced with proton tags has known quantum numbers Excellent mass resolution (~GeV) from the protons, independent of the decay products of the central system CP violation in the Higgs sector manifests itself as azimuthal asymmetry of the protons Proton tagging may be the discovery channel in certain regions in the MSSM Vacuum quantum numbers “Double Pomeron exchange” shields color charge of other two gluons The physics interest of DPE Higgs production As the delivered luminosity reaches tens of fb -1 the central exclusive production (CEP) processes become a tool to search for new physics See B. Cox’s talk

11. 11 DIS06, 20-24/04/06, M. Ruspa Vacuum quantum numbers “Double Pomeron exchange” shields color charge of other two gluons The physics interest of DPE Higgs production  b jets : M H = 120 GeV  · BR = 2 fb (uncertainty factor ~ 2.5) M H = 140 GeV  ·  = 0.7 fb M H = 120 GeV : 11 signal / O(10) background in 30 fb -1 after detector cuts  WW * : M H = 120 GeV  · BR = 0.4 fb M H = 140 GeV  · BR = 1 fb M H = 140 GeV : 8 signal / O(3) background in 30 fb -1 after detector cuts  b-jet channel very important in “intense coupling regime” of MSSM, cross section factor 10-20 larger, discovery channel? See B. Cox’s talk As the delivered luminosity reaches tens of fb -1 the central exclusive production (CEP) processes become a tool to search for new physics

12. 12 DIS06, 20-24/04/06, M. Ruspa  1  2 s = M 2 With √s = 14TeV, M H = 120 GeV on average:   0.009  1% DPE Higgs production: necessary ingredients Nominal LHC beam optics @ 10 33 - 10 34 cm -2 s -1 : 220 m: 0.02 <  < 0.2 420m: 0.002 <  < 0.02 beam p’ roman pots dipole

13. 13 DIS06, 20-24/04/06, M. Ruspa Trigger studies “Diffractive Higgs: CMS/TOTEM level-1 trigger studies” M. Arneodo, V. Avati, R. Croft, F. Ferro, M. Grothe, C. Hogg, F. Oljemark, K. Osterberg, M. Ruspa Proceedings of “ HERA and the LHC: A Workshop on the Implications of HERA for LHC Physics", CERN-DESY 2004/2005, p. 455-460; hep-ph/0601013  Semileptonic WW and tau tau decay channels (or any final state with high-p T leptons, missing E T ): trigger not a problem!  Most challenging case is H (120 GeV)  bb

14. 14 DIS06, 20-24/04/06, M. Ruspa < 100 Hz < 100 kHz 40 MHz collision High-Level Trigger HLT Level-1 trigger Calo Muon no tracking! Triggering jets at CMS ECAL HCAL PbWO4 crystal  veto patterns Trigger tower  4x4 trigger towers = region  Search for jets with a sliding 3x3 regions window  Jet = 3x3 region with local energy max in middle  Reconstructed L1 jet E T on average ~ 60% of real jet E T, thus need for jet E T calibration  Jet = 144 trigger towers, with typical jet dimensions: Dh x Df = 1 x 1

15. 15 DIS06, 20-24/04/06, M. Ruspa L1 jet trigger signature for a 120 GeV Higgs: 2 jets in CMS Cal, E T < 60 GeV each  Measured L1 jet E T on average only ~60% of true jet E T  L1 trigger applies jet E T calibration and cuts on calibrated value  Thus: 40 GeV (calibrated) ~ 20 to 25 GeV measured  Cannot go much lower because of noise The difficulty of triggering on a light Higgs while considered acceptable: O(1Khz)  Need additional conditions in trigger Use rate/efficiency @ L1 jet E T cutoff of 40 GeV as benchmark

16. 16 DIS06, 20-24/04/06, M. Ruspa + H T condition = isolation condition for jets: 2 jets in central Cal (|η| threshold H T = scalar sum of E T of all jets in the event with E T (jet) > threshold  factor 2 rate reduction L1 2-jet trigger +…

17. 17 DIS06, 20-24/04/06, M. Ruspa + H T condition = isolation condition for jets: 2 jets in central Cal (|η| threshold H T = scalar sum of E T of all jets in the event with E T (jet) > threshold  factor 2 rate reduction + Conditions based on TOTEM detectors T1 e T2: excellent suppression of QCD bacground useless as soon as pile-up events are present as also signal events are vetoed (non-diff. component in pile-up events tends to quickly fill in the rapidity gaps). L1 2-jet trigger +…

18. 18 DIS06, 20-24/04/06, M. Ruspa + H T condition = isolation condition for jets: 2 jets in central Cal (|η| threshold H T = scalar sum of E T of all jets in the event with E T (jet) > threshold  factor 2 rate reduction + Conditions based on TOTEM detectors T1 e T2: excellent suppression of QCD background useless as soon as pile-up events are present as also signal events are vetoed (non-diff. component in pile-up events tends to quickly fill in the rapidity gaps). + Topological condition: 2 jets required to be in the same η hemisphere as the RP detectors that see tthe proton  factor 2 rate reduction L1 2-jet trigger +…

19. 19 DIS06, 20-24/04/06, M. Ruspa L1 2-jet trigger +… + Single-arm 220 m condition:  mass resolution for CEP Higgs is worst than with 420 m tag Integrated QCD rate for events with at least two jets Integrated QCD rate for events with at least two jets and which satisfy the single-arm 220 m RP condition kHz L=10 32 cm -2 s -1 Plot: Richard Croft

20. 20 DIS06, 20-24/04/06, M. Ruspa L1 2-jet trigger +… + Single-arm 220 m condition:  very good reduction of rate in absence of pile-up  reduction decreases substantially in the presence of pile-up + Single-arm 220 m condition with  cut TOTEM will provide implementation of a  cut at L1 (e.g.  < 0.1, recall acceptance is 0.02 <  < 0.2). Implementation and achievable resolution under study..  Achievable total reduction: 10 x 2 (HT cond.) x 2 (topological cond.) = 40!

21. 21 DIS06, 20-24/04/06, M. Ruspa For H (120 GeV, DPE)  b bbar, adding L1 conditions on the RPs at 220m is likely to provide a rate reduction sufficient to meet the CMS L1 bandwidth limits at luminosities up to 2x 10 33 cm -1 s -1 To go even further up in luminosity need additional handle to stay within bandwidth limits... So what about triggering with the 420 m RPs ? At the current CMS L1 latency of 3.2  s they are too far away from IP for inclusion in L1 Note: This is a hardware limit - cannot be changed without replacing trigger pipelines of CMS tracker and preshower detectors with deeper ones Should this however happen (under discussion for SLHC: L1 latency 6.4  s, determined by ECAL pipeline depth) then.... Triggering on a light Higgs

22. 22 DIS06, 20-24/04/06, M. Ruspa L1 2-jet trigger +…  Achievable total reduction: 75 x 2 (HT cond.) x 2 (topological cond.) = 300! + Asymmetric 220 & 420 condition:  in effect means on opposite sides events where  values of 2 protons are very different  can be used either in L1 after increase in L1 latency or on HLT!

23. 23 DIS06, 20-24/04/06, M. Ruspa L1 efficiency – RP condition How much is left of our signal? Without RP condition Various RP conditions Plots: Richard Croft

24. 24 DIS06, 20-24/04/06, M. Ruspa H  bb (120 GeV): relatively muon-rich final state from B-decays - about 20% of events have at least one muon in the final state How many signal events are being retained by the already foreseen CMS trigger streams, notably the muon trigger? L1 signal efficiency – muon condition  Half of events with a muon in the final state can be triggered with aa 1 muon + 1 jet trigger (to be implemented) H  WW(140 GeV): about 23% of events have at least one muon in the final state:  70% of events with CMS L1 single muon trigger Numbers: F. Oljemark

25. 25 DIS06, 20-24/04/06, M. Ruspa Single diffractive production of W, Z, dijets DPE processes constitute only a small part of the diffractive cross section that can be explored by CMS and TOTEM. Exemplary of any process that deposits low E T in the central detector.

26. 26 DIS06, 20-24/04/06, M. Ruspa Recall: RP acceptances at  * = 0.5 m: 220m - 0.02 <  < 0.2 420m – 0.002 <  < 0.02 Lowest threshold for L1 jet trigger is E T > 40 GeV Typical loss of factor 2 in efficiency when using 220 m RP cond. (RP acceptance) Map the parameter space (bandwidth vs efficiency) with ultimate goal of defining a trigger table for a dedicated diffractive trigger stream with target output rates of 1 kHz (L1) and 1 Hz (HLT) Use POMWIG Monte Carlo Single diffractive production of W, Z, dijets Plot: Richard Croft

27. 27 DIS06, 20-24/04/06, M. Ruspa  At LHC startup, where the luminosity will be low, and where no pile-up is present, CMS can pursue a rich program of rapidity-gap based diffractive and fwd physics  Should the FP420 R&D project result in upgrading CMS with detectors 420 m away from the IP, proton-tag based program and discovery physics becomes possible  Wide proton-tag based program ranging from QCD to the low-x structure of the proton to photon physics already possible by way of a collaboration of CMS with TOTEM Summary  Key element is trigger, notably at high lumi, when amount of pile-up collisions overlaid to the interesting hard event becomes high. Pile-up events are themselves largely diffractive

28. 28 DIS06, 20-24/04/06, M. Ruspa  Triggering in absence of pile-up: no problem.  L1 2-jet rate for central with L1 jet E T cutoff of 40 GeV must be reduced to O(1Khz) to accomplish with CMS L1 bandwith restrictions. Therefore using L1 jet trigger alone not an option in the presence of pile-up.  Can trigger with the central detector alone by using the muon trigger Efficiencies with already foreseen CMS L1 thresholds: 10% for H(120GeV)  bb, 20% for H(140GeV)  WW*  Can also use the L1 jet trigger when combining it with RP condition at (rate of a few kHz achievable at 2x10 33 cm -1 s -1 ). Requires defining a new CMS trigger stream; efficiencies around 10%.  L1 efficiencies for SD production of W’s, Z’s, die-jets available.  A dedicated trigger stream hence feasible, with output rates of O(1) kHz L1, efficient for selecting CEP, a potential discovery channel for a light Higgs boson, and hard single diffractive processes. Triggering diffraction at CMS: summary

29. 29 DIS06, 20-24/04/06, M. Ruspa BACKUP

30. 30 DIS06, 20-24/04/06, M. Ruspa Beam-halo/beam-gas level numbers produced by TOTEM not a problem as soon as central CMS detector condition is used in L1 Find from PYTHIA pile-up sample: @220m: 0.012 protons per pile-up event on average, i.e. at 10 34 cm -2 s -1 : 35*0.055=1.93  @220m: In worst case on average 1.93 tracks from pile-up in addition to track from signal event @420m: 0.055 protons per pile-up event on average, i.e. at 10 34 cm -2 s -1 : 35*0.012=0.42  @420m: In worst case on average 0.42 tracks from pile-up in addition to track from signal event Background in RPs The reduction factors in the presence of pile-up obtained by scaling the probability per pile-up event to satisfy the relevant RP condition, determined separately, by the average number of pile-up events at the luminosity in question.

31. 31 DIS06, 20-24/04/06, M. Ruspa No problem for processes with a lepton in the final state H (120 GeV)  bbbar  For luminosities up to 2x10 33 cm -2 s -1 possible to keep a reasonable fraction of events  At higher luminosities ~ 10% can always be kept by triggering on muons MSSM scenario:  discovery can be made with lumi at or below 1x10 33 cm -2 s -1  at higher luminosities triggering on muons from b-decay

32. 32 DIS06, 20-24/04/06, M. Ruspa Other L1 conditions  Effect of combining aready foreseen L1 trigger conditions with conditions on the RP detectors  Large rapidity gap cut at L1 (jets veto in forward calorimeter)  Further rate reduction (approx. factor 2) at lumi where pile-up is negligible Estimated 1kHz Jet Thresholds for various Central / RP conditions S: single-sided, D: double-sided C:  <0.1 of the leading proton

33. 33 DIS06, 20-24/04/06, M. Ruspa L1 2-jet trigger +… + Double-arm 420 condition:  only possible after increase of L1 latency  would allow to select events that are gold plated wrt mass resolution  note: single-sided 220 m cond. and asymmetric cond. select events with worst possible mass resolution At 420 m & 420 m 500 150 30 10  Achievable total reduction: 30 x 2 (HT cond.) x 2 (topological cond.) = 120!

34. 34 DIS06, 20-24/04/06, M. Ruspa A)L1: 220 m single-arm condition with a  cut B) Back-to-backness of jets (2.8 < ΔΦ< 2.48 rad) and (E 1 T –E 2 T )/(E 1 T + E 2 T ) 40 GeV C)  reconstructed from jets in the central detector  +(-) = s-½∑E T i exp(-(+)η i ); cut: difference between 2  values larger than 2σ. No simulation of RP reconstruction available so far. Assumed  resolution of 15% (20%) at 220 (420) m D) Either one of the 2 jets b-tagged E) A proton seen at 420 m No pile-up case: no QCD bgd survives selection. HLT selection cond.A+B+CA+B+DA+B+C+E HLT rate L=1x10 33 cm -2 s -1 15 Hz20 Hz< 1Hz HLT rate L=2x10 33 cm -2 s -1 60 Hz80 Hz1 Hz Signal eff. H  bb (120 GeV)11%7%6% Desired target output rate; no loss in efficiency compared to L1 HLT studies

35. 35 DIS06, 20-24/04/06, M. Ruspa FAMOS (Fast CMS Simulation) + RPs acceptance tables DPEMC MC: tt production  inclusive DPE for the semileptonic channel (tt  bb qq μ ν )  good rejection of QCD background obtained  for SD the cross section should increase by a factor 30-40 B production  SD and DPE production of B-mesons with B  J/psi  μ μ  tens of events for 10 fb -1 in DPE case and several hundreds in SD case W and WW production  DPE inclusive W production: abundant process can be studies at lumi where pile up is small  DPE exclusive WW production: 10 events in 10 fb -1 N.B.: 10 fb -1 collected in  60 days of LHC running @ 2x10 33 cm -2 s -1 Hard diffractive QCD studies

36. 36 DIS06, 20-24/04/06, M. Ruspa Inclusive dijet production pp  pXjjp  Was used by CDF to measure diffractive structure function of the proton: similar measurement possible at CMS, with wider kinematic coverage (  > 0.02 (0.002) compared to  > 0.035 at CDF); statistical accuracy of CDF measurement could be reached within a few days of running at ~10 32 cm -2 s -1  Comparison of DPE and SD rates for dijet production would give information on the hard diffractive factorisation breaking at the LHC Exclusive dijet production pp  pjjp  Cross section for central exclusive production of dijets order of 1 nb  high rate allows precise determination of the off-diagonal un-integrated gluon densities  uncertainties in exclusive production cross section of Higgs to be reduced to 1% level Hard diffractive dijet prod.

37. 37 DIS06, 20-24/04/06, M. Ruspa Events with a fast proton in the final state can also originate from the exchange of a vector boson. In particular, tagging one leading proton allows the selection of photon-proton events with known photon energy; likewise tagging two leading protons gives access to photon-photon interactions of well known center of mass energy [PRD 63 070152, hep-ex/0201027]. γp and γγ physics p p  e.g.: exclusive 2- γ production of lepton pairs is an important calibration process (forward e+e- pairs in Castor with proton tag, observed cross section 3 pb, μ+μ- would double the statistics)

38. 38 DIS06, 20-24/04/06, M. Ruspa SM Higgs with ~120 GeV: gg  H, H  b bbar mode has highest BR But signal swamped by gg  b bbar Best bet with CMS: H  , where in 30 fb -1 S/√B  4.4 Light SM Higgs at the LHC (I)

39. 39 DIS06, 20-24/04/06, M. Ruspa Production cross section times branching ratio for CEP From implementation of KMR model in Exhume MC Light SM Higgs at the LHC (II)

40. 40 DIS06, 20-24/04/06, M. Ruspa Intense-coupling regime of the MSSM: M h ~M A ~ M H ~ O(100GeV): their coupling to , WW*, ZZ* strongly suppressed  discovery very challenging at the LHC Cross section of two scalar (0+) Higgs bosons enhanced compared to SM Higgs  CEP as discovery channel see Kaidalov et al, hep-ph/0307064, hep-ph/0311023 100 fb 1 fb 120 140 - “3-way mixing” scenario of CP-violating MSSM: the 3 neutral Higgs bosons are nearly degenerate, mix strongly and have masses close to 120 GeV Superior mass resolution from tagged proton allows disentangling the Higgs bosons by measuring their production line shape Explicit CP-violation in Higgs sector visible as asymmetry in the azimuthal distribution of tagged protons (interference of P- and P+ amplitudes) (Khoze et al., hep-ph/0401078)  CEP as CP and line-shape analyzer ! MSSM and proton tagging

41. 41 DIS06, 20-24/04/06, M. Ruspa Difference between DPEMC and (EDDE/ExHuMe) is an effect of Sudakov suppression factor growing as the available phase space for gluon emission increases with increasing mass of the central system Models predict different physics potentials ! DPE Higgs production: models (I)

42. 42 DIS06, 20-24/04/06, M. Ruspa Diffractive Higgs productions: models (II) Different models give different predictions for  The cross sections  The mass/energy dependence of the cross sections J. Forshaw BL Bialas Landshof (soft Pomeron) KMR: Khoze Martin Ryskin Tevatron can test these models Almost all calculations now converge to a cross section of 2-10 fb for a light Higgs DPEMC ExHume

43. 43 DIS06, 20-24/04/06, M. Ruspa More central rapidity in ExHuMe due to gluon distr. falling more sharply than the Pomeron parameterisation in DPEMC N.B: acceptance of forward proton taggers sensitive to the rapidity distribution of central system. Cut ξ = 0.1 applied in DPEMC as required by Bialas-Landshoff appr. DPE Higgs production: models (III)

44. 44 DIS06, 20-24/04/06, M. Ruspa DPE Higgs event generators 1. DPEMC 2.4 (M.Boonekamp, T.Kucs) - Bialas-Landshof model for Pomeron flux within proton - Rap. gap survival probability = 0.03 - HERWIG for hadronization 2. EDDE 1.2 (V.Petrov, R.Ryutin) - Regge-eikonal approach to calculate soft proton vertices - Sudakov factor to suppress radiation into rap.gap - PYTHIA for hadronization 3. ExHuMe 1.3 (J.Monk, A.Pilkington) - Durham model for exclusive diffraction (pert. calc. by KMR) - Improved unintegrated gluon pdfs - Sudakov factor to suppress radiation into rap.gap + rap.gap survival prob.= 0.03 - PYTHIA for hadronization All three models available in the fast CMS simulation

45. 45 DIS06, 20-24/04/06, M. Ruspa DPE Higgs production studies Models: EDDE, EXHUME, DPEMC, all in FAMOS; RPs acceptance tables H  bb in SM: back-to-backness of the jets, b-tag, two final state protons, consistency of mass reconstruction between RPs and central detector:  2-4 signal events per 30 fb -1  suppression of backgrounds rely on resolution of RP H  WW* in SM [EPJ C45 (2006) 401]:  1-7 events depending on mass range per 30 fb -1  suppression of background does not rely on resolution of RPs  irreducible backgrounds small and controllable N.B.: 30 fb -1 collected in  30 days of LHC running @ 10 34 cm -2 s -1

46. 46 DIS06, 20-24/04/06, M. Ruspa - Recent versions of DPEMC, EDDE and ExHuMe generators as well as new RP acceptances available in CMS fast simulation - H->bb: Difficult channel. Cross sections, RP and b-tag efficiencies for signal well established but the selection cuts still being tuned. BG = ISSUE ! None of the models treats bg properly. The bg issue needs an input from theory side. - Comparison of generators: Rich resource in HERA-LHC proceedings Non-negligible differences in basic quantities ( ξ and yH) influencing RP acceptances - Comparison to data: Hard task to make a comparison to the only avail. data (Rjj distr. from RunII). Hope to get a good description, though. DPE Higgs production studies

47. 47 DIS06, 20-24/04/06, M. Ruspa - H->WW in SM: Solid numbers for signal including L1-trigger Bg is small and controllable Promising channel for mh>130 GeV - H->WW (bb,tautau) in MSSM: Idea of Durham group (V.Khoze et al.). In some scenarios and in some regions of (mA,tan β ) a much higher yield than in SM case. Especially promising for Higgs -> bb and Higgs -> tautau channels DPE Higgs production studies

48. 48 DIS06, 20-24/04/06, M. Ruspa Photon fluxes introduced in CALCHEP/COMPHEP, photon events then fed to PYTHIA for decays and hadronization CMS full detector simulation + RPs acceptance tables γγ interactions:  2-γ production of W pairs: studies of quartic gauge couplings γγWW (LEP limits are weak due to limited cms energy)  Exclusive 2- γ production of lepton pairs is an important calibration process (forward e+e- pairs in Castor with proton tag, observed cross section 3 pb) γp interactions:  photoproduction of H: significant cross-section at LHC and good signal-to-background ratio; low mass region with Higgs decaying to bb,  and W;  W boson production at high transverse momentum, top pair production via photon-gluon fusion, … DY: qqbar  ll gammagamma  ll γp and γγ physics

49. 49 DIS06, 20-24/04/06, M. Ruspa Drell-Yan

50. 50 DIS06, 20-24/04/06, M. Ruspa HERA  x down to 10 -5 ; LHC can probe very low x down to 10 -6, 10 -7 Low-x studies Drell-Yan: pp  qq   */Z  e + e - X  Sensitive to very low-x partons in the proton (x~10 -6 to 10 -7 )  Detect electrons in CASTOR (5.2 < |  | < 6.6)  Can enhance signal/background ratio by requiring track in T2

51. 51 DIS06, 20-24/04/06, M. Ruspa Survey of accessible diff/fwd processes (III) Inclusive DPE prod of t tbar: (A. Vilela Pereira)  semileptonic decay channel: pp  p+X+(tt)+X+p; tt  bbqq    DPEMC and Pomwig generators  Require 2 protons in 220m and/or 420m detectors  Event yield 1-10 per 10fb -1, depending on theoretical model, but taking supression factor of 0.03 into account DPE and SD prod of B  J/    (D. Damiao) DPEMC MC Event yields per 10 pb -1 : DPE: tens of events SD: several hundreds of events SD and DPE with hard scale: Production of heavy quarks

52. 52 DIS06, 20-24/04/06, M. Ruspa Survey of accessible diff/fwd processes (IV) DPE pp  pYWp DPE excl prod pp  pWWp dominated by QED  DPEMC MC  require 2 protons, in 220m and/or 420m detectors  several thousand events of type W  eand W  expected per 1 fb -1  together with SD prod of W can be used to measure hard diffractive factorisation breaking with LHC data alone DPE with hard scale: DPE prod of W and W-pairs (A. Loginov)  DPE prod of W-pairs relatively rare process  dominated by QED  require 2 protons, in 220m and/or 420m detectors  expects about 1 event per fb -1  this small SM expectation would allow detection of anomalous WW prod, as e.g. predicted in theory of supercritical pomeron