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Forward Physics with the TOTEM  CMS at the LHC Risto Orava

Forward Physics with the TOTEM  CMS at the LHC Risto Orava. Forward physics at the LHC Signature studies Experimental layout An example: pp p+H+p Outlook. XIII ISVHECRI Pylos, Greece, 6-12 September 2004 R.Orava.

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Forward Physics with the TOTEM  CMS at the LHC Risto Orava

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  1. Forward Physics with the TOTEMCMS at the LHC Risto Orava • Forward physics at the LHC • Signature studies • Experimental layout • An example: ppp+H+p • Outlook XIII ISVHECRI Pylos, Greece, 6-12 September 2004 R.Orava Low-x Workshop, Prague 17 September 2004 Risto Orava

  2. The Large Hadron Collider (LHC) pp collisions at 14 TeV LHC is built into 27 km the LEP tunnel • 5 experiments • 25 ns bunch spacing •  2835 bunches • 1011 p/bunch • Design Luminosity: • 1033cm-2s-1 -1034cm-2s-1 • 100 fb-1/year 23 inelastic events per bunch crossing CMS/TOTEM ALICE LHC-B ATLAS Planned Startup on Spring 2007

  3. Total TOTEM/CMS acceptance (b*=1540m) RPs microstation at 19m? Important part of the phase space is not covered by the generic designs at LHC. TOTEM  CMS Covers more than any previous experiment at a hadron collider. Charge flow information value low: - bulk of the particles crated late in space-time leading protons leading protons Energy flow information value high: - leading particles created early in space-time TOTEM + CMS In the forward region (|h > 5): few particles with large energies/small transverse momenta.

  4. Diffractive Scattering has distinctive signatures ‘wee’ partons  lns Elastic soft SDE hard SDE hard CD s-channel view p jet lnMX2 Baryonic charge distribution r  0.4fm jet Valence quarks in a bag with r  0.1fm lns h Rapidity gap survival & ”underlying” event structures are intimately connected with a geometrical view of the scattering - eikonal approach! p Soft diffractive scattering Hard diffractive scattering ’Glansing’ scattering of proton fields R.Orava

  5. How to manage with the high-pT signatures in the environment of an underlying event? Min-Bias Min-Bias • LHC: most of collisions are “soft’’, outgoing particles roughly in the same direction as the initial protons. • Occasional “hard’’ interaction results in large transverse momentum outgoing partons. • The “Underlying Event’’ is everything but the two outgoing Jets, including : initial/final gluon radiation beam-beam remnants secondary semi-hard interactions • Unavoidable background to be removed from the jets before comparing to NLO QCD predictions How do we control the kinematics (DIS vs. hh)?

  6. Photon - Pomeron interferencer Pomeron exchange (~exp Bt) diffractive structure pQCD Ldt = 1033 & 1037 cm2 Studying elastic scattering an soft diffraction requires special LHC optics. These will yield large statistics. ds/dt (mb/GeV2) high-t (* = 1540 m & 18 m)

  7. Diffractive Cross Sections are Large Rel = sel(s)/stot(s) Rdiff = [sel(s) + sSD(s) + sDD(s)]/stot(s) 0.30 0.375 • sel  30% of stot at the LHC ? • sSD + sDD  10% of stot (= 100-150mb) at the LHC ?

  8. Inelastic rates are uncertain in the forward region Event selection: • trigger from T1 or T2 (double arm o single arm) • Vertex reconstruction (to eliminate beam-gas bkg.) Extrapolation for diffractive events needed Lost events simulated extrapolated Acceptance Loss at low masses detected

  9. TOTEM will measure stot to 1% TOTEM

  10. Additional forward coverage opens up new complementary physics program at the LHC • Investigate QCD:stot, elastic scattering, soft & hard diffraction, multi- rapidity gap events (see: Hera, Tevatron, RHIC...) - confinement. • Studies with pure gluon jets: gg/qq… - LHC as a gluon factory! • Gluon density at small xBj (10-6 – 10-7) – “hot spots” of glue in vacuum? • Gap survival dynamics, proton parton configurations (pp3jets+p) – underlying event structures • Diffractive structure: Production of jets, W, J/, b, t, hard photons, • Parton saturation, BFKL dynamics, proton structure, multi-parton scattering • Search for signals of new physics based on forward protons + rapidity gaps Threshold scan for JPC = 0++ states in: pp  p+X+p – spin-parity of X! (LHC as the e+e- linear collider in gg-mode.) • Extension of the ‘standard’ physics reach of the CMS experiment into the forward region • Luminosity measurement with DL/L 5 %

  11. As a Gluon Factory LHC could deliver... • О(100k) high purity (q/g = 1/3000) gluon jets with ET >50 GeV • in 1 year; gg-events as “Pomeron-Pomeron” luminosity monitor • Possible new resonant states, e.g. Higgs (О(100) H  bb events per • year with mH = 120 GeV, L=1034)*, glueballs, quarkonia 0++ (b ), • gluinoballs - complementary to inclusive analyses (bb, WW & t+t- decays) • Invisible decay modes of Higgs (and SUSY)?! • CP-odd Higgs • Squark & gluino thresholds well separated • - practically background free signature: multi-jets & ET • - model independence (missing mass!) [expect O(10) events for gluino/squark masses of 250 GeV] • - an interesting scenario: gluino as the LSP with mass window 25-35 GeV(S.Raby) • O(10) events with isolated high mass ggpairs, extra dimensions

  12. longer Q2 extrapolation smaller x Low-x Physics at the LHCGain in x-reach & Q2-range J. Stirling

  13. Relative precision on the measurement of HBR for various channels, as function of mH, at Ldt = 300 fb–1. The dominant uncertainty is from Luminosity: 10% (open symbols), 5% (solid symbols). (ATL-TDR-15, May 1999) In addition: The signatures of new physics have to be normalized: The Luminosity Measurement Luminosity relates the cross sectionsof a given process by: L = N/s A process with well known, calculable and large s (monitoring!) with a well defined signature? Need complementarity. Measure simultaneously elastic (Nel) & inelastic rates (Ninel), extrapolateds/dt  0, assumer-parameter to be known: (1+r2) (Nel + Ninel)2 L = 16p dNel/dt|t=0 Ninel = ?  Need a hermetic detector. dNel/dtt=0 = ?  Minimal extrapolation to t0: tmin 0.01

  14. Forward Physics Scenarios Proton b* (m) rapidity gap L(cm-2s-1) inelastic activity jet g,e,m,t L, D++,... TOTEM & CMS TOTEM & CMS TOTEM & CMS elastic scattering 1540 18 beam halo? 1028 -1032 total cross section inelastic acceptance 1540 1028 -1033 soft diffraction 1540 200-400 gap survival L, K±, ,... 1029 -1031 mini-jets? 200-400 0.5 jet acceptance central & fwd W, Z, J/,... hard diffraction 1031 -1033 200-400 0.5 di-jet backgr central pair b-tag, g, J/,... DPE Higgs, SUSY,... 1031 -1033 trigger 200-400 0.5 mini-jets resolved? central & fwd jets di-leptons jet-g,... low-x physics 1031 -1033 exotics (DCC,...) p± vs. po multiplicity jet anomalies? leptons g’s,...? 0.5 1031 -1033 R.Orava

  15. Correlation with the CMS Signatures • e, g, m, t, and b-jets: • tracking: |h| < 2.5 • calorimetry with fine granularity: |h| < 2.5 • muon: |h| < 2.5 • Jets, ETmiss • calorimetry extension: |h| < 5 • High pT Objects • Higgs, SUSY,... • Precision physics (cross sections...) • energy scale: e & m 0.1%, jets 1% • absolute luminosity vs. parton-parton luminosity via • ”well known” processes such as W/Z production? R.Orava

  16. To Reach the Forward Physics Goals We Need: • Leading Protons • Extended Coverage of Inelastic Activity • CMS

  17. Need to Measure Inelastic Activity and Leading Protons over Extended Acceptance in , ,  and –t. Measurement stations (Roman Pots) at locations optimized vs. the LHC beam optics. Both sides of the IP. LP1 LP2 LP3 147 m 180 m 220 m Measure the deviation of the leading proton location from the nominal beam axis () and the angle between the two measurement locations (-t) within a doublet. Acceptance is limited by the distance of a detector to the beam. Resolution is limited by the transverse vx location (small ) and by beam energy spread (large ). For Higgs, SUSY etc. heavier states need LP4,5 at 300-400m!

  18. TOTEM ROMAN POT IN CERN TEST BEAM

  19. Microstation – Next Generation Roman Pot -station concept (Helsinki proposal) Silicon pixel detectors in vacuum (shielded) Very compact A solution for 19m, 380 & 420m? Movable detector

  20. Diffraction at high b*: Acceptance Luminosity 1028-1030cm-2s-1 (few days or weeks) • more than 90% of all diffractive protons are seen! • proton momentum can be measured with a resolution of few 10-3

  21. CMS tracking is extended by forward telescopes on both sides of the IP CMS T1-CSC: 3.1 < h < 4.7 T2-GEM: 5.3 <h< 6.5 T3-MS: 7.0 <h< 8.5 ? T1 T2 10.5 m CASTOR ~14 m T3? ~19 m - A microstation (T3) at 19m is an option.

  22. Running Scenarios 1: High & Intemediate b* - low b* physics will follow...

  23. The process: pp  p + H + p h p 10 p1 p’ Dh 5 b-jet 0++ q1 b - H 0 q2 b 0++ - b-jet -5 Dh p2 p” -10 p MH2 = (p1 + p2 – p’ – p”)2  x1x2s (at the limit, where pT’ & pT” are small) x1 = 1-p’q1/p1q1  1-p’/p1x2 = 1-p”q2/p2q2  1-p”/p2

  24. Leading proton studies at low * • GOAL: New particle states in Exclusive DPE • L > few 10 32 cm2 s1 for cross sections of ~ fb (like Higgs) • Measure both protons to reduce background from inclusive • Measure jets in central detector to reduce gg background • Challenges: • M  100 GeV  need acceptance down to ’s of a few ‰ • Pile-up events tend to destroy rapidity gaps  L < few 10 33 cm2 s1 • Pair of leading protons  central mass resolution  background • rejection A study by the Helsinki group in TOTEM.

  25. Central Diffraction produces two leading protons, two rapidity gaps and a central hadronic system. In the exclusive process, the background is suppressed and the central system has selected quantum numbers. Survival of the rapidity gaps?1 JPC = 0++ (2++, 4++,...) MX212s Measure the parity P = (-1)J: ds/d 1 + cos2 2p  Gap Jet+Jet Gap 0 hmin h hmax Mass resolution  S/B-ratio R.Orava 1 V.A.Khoze,A.D.Martin and M.G.Ryskin, hep-ph/0007359

  26. The Experimental Signatures: pp  p + X + p - vertex position in the transverse plane? b-jet Detector Detector CMS p2’ p1’ _ - b-jet - resolution in x ? -beam energy spread? Aim at measuring the: • Leading protons on both sides down to D  1‰ • - Rapidity gaps on both sides – forward activity – for |h| > 5 • Central activity in CMS

  27. Leading Proton Detection 0m 147m 180m 220m 308m 338m 420 430m D2 Q4 Q5 Q6 Q7 B8 Q8 B9 Q9 B10 Q10 B11 IP    D1    Q1-3      x = 0.02   Jerry & Risto

  28. Mass Acceptance Both protons are seen with  45 % efficiency at MX = 120 GeV Some acceptance down to: MX = 60 GeV 308m & 420m locations select symmetric proton pairs  acceptance decreases. All pp p + X + p 308 m 420 m MX = 120 GeV e 45% All detectors combined MX = 60 GeV e 30% 308m e 15% 420m MX (GeV)

  29. Momentum loss resolution at 420 m Resolution improves with increasing momentum loss Dominant effect: transverse vertex position (at small momentum loss) and beam energy spread (at large momentum loss, 420 m)/detector resolution (at large momentum loss, 215 m & 308/338 m) proton momentum loss proton momentum loss

  30. DPE Mass Measurement at 400m Gaussian s(M) vs. central mass assuming DxF/xF = 10-4 s(M) = (1.5 - 3.0) GeV (DxF/xF = (1-2)10-4) s(M) (GeV) • Note: s(M)/M = 1.1% s(M) = 1.3 GeV - Gaussian width • To contain 87% of the signal need 3xs(M) = 3.9 GeV symmetric case:  65% of the data 20 GeV < MX < 160 GeV (MXmax determined by the aperture of the last dipole,B11, MXmin by the minimum deflection = 5mm) Central Mass (GeV) Helsinki group/J.Lamsa & R.O.

  31. SUMMARY: TOTEM opens up Forward Physics to the LHC TOTEMCMS covers more phase space than any previous experiment at a hadron collider. • Fundamental precision measurements on elastic scattering, total cross section and QCD: • non-perturbative structure of proton • studies of pure gluon jets – LHC as a gluon factory • gluon densities at very small xBj… • parton configurations in proton • Searches for signals of new physics: • Threshold scan of 0++ states in exclusive central diffraction: Higgs, • SUSY (mass resolution crucial for background rejection) • Extension of the ‘standard’ physics reach of CMS into the fwd region & Precise luminosity measurement

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