1 XXXV ISMD 2005 KROMĚŘÍŽ, CZECH TOTEM Physics Scenarios at the LHC; Elastic Scattering, Total Cross section, Diffraction, and beyond... Risto Orava HIP & UH

2 TOTEM Experiment CMS Experimental Area (IP5) Leading Protons measured at +147m & +220m from the CMS Leading Protons measured at -220m & -147m from the CMS (Also CMS is here...) Leading protons are detected at  147m &  220m from the IP. CMS coverage is extended by Totem T1 and T2 spectrometers. Additional forward calorimetry & veto counters are under planning. CMS is TOTEMized... XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

3 Configuration of the Experiment b-jet CMS - Leading protons on both sides down to   1 ‰ - Rapidity gaps on both sides – forward activity – for |  | > 5 - Central activity in CMS - Aim at measuring the: Roman Pot Station at 147 / 220m Aim at detecting colour singlet exchange processes with the leading protons scattered at small angles with respect to the beam. Roman Pot Station at 147/220m CASTOR T1 T2 CASTOR XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

 p T (GeV) CMS ATLAS ALICE LHCb Base Line LHC Experiments: p T -  coverage Exp B (T) p T  (GeV) ALICE ATLAS CMS LHCb 4Tm 0.1 The base line LHC experiments will cover the central rapidity region - TOTEM  CMS will complement the coverage in the forward region. T1 T2 RP LHC TOTEMized microstation veto p T max ~  s exp(-  ) XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

5 ATLAS & CMS: Energy flow in |  |  5 Minimum bias event structure need to sort out the pile-up events at L › present MC models differ by large factors ALICE: Charged multiplicities in -5    3 Zero Degree Calorimetry (neutral & charged) TOTEM: Charged multiplicities: 3    7 Leading particle measurement: Totem sees ~ all diffractively scattered protons TOTEM/CMS inelastic coverage is unique: Holes only at  ~ 5 & 7-9 (could be covered with  s & veto counters) Base Line LHC Experiments XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

6 Diffractive scattering is a unique laboratory of confinement & QCD: A hard scale + hadrons which remain intact in the scattering process. Soft diffractive scattering: -large b Hard diffractive scattering - small b Valence quarks in a bag with r  0.1fm Baryonic charge distribution- r  0.5fm Rapidity gap survival & ”underlying” event structures are intimately connected with a geometrical view of the scattering - eikonal approach! Longitudinal view - Lorentz contracted – not to scale!  p p lnM X 2 jet Elasticsoft SDE hard SDE hard CD Totem sees SDE M X  20 GeV lns rapidity Cross sections are large. 10mb?25mb?1mb? Hard processes: Jet momenta correlated with the initial parton momenta. Soft processes: Coherent interactions -impact parameter picture. + Transversal view ‘wee’ parton cloud - grows logarithmically b b soft CD XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

7 With the leading protons and additional forward coverage a new physics realm opens up at the LHC: Hard diffraction with multi- rapidity gap events (see: Hera, Tevatron, RHIC...)  Problems intimately related to confinement. –Gluon density at small x Bj (10 -6 – ) – “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 –Studies with pure gluon jets: gg/qq…  LHC as a gluon factory! (see: KMR EPJC19(2001)477) Signals of new physics based on forward protons + rapidity gaps  Threshold scan for J PC = 0 ++ states in: pp  p+X+p – Spin-parity of X ! (LHC as the pre -e + e - linear collider in the  -mode.) Extend ‘standard’ physics reach of the CMS experiment into the forward region:  Full Monty! Measure the Luminosity with the precision of  L/L  5 % (KMRO EPJC19(2001)313) Elastic scattering,  tot and soft diffraction – surely... But also: XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

8 As a Gluon Factory LHC could deliver... High purity (q/g ~ 1/3000) gluon jets with E T > 50 GeV ; gg-events as “Pomeron-Pomeron” luminosity monitor Possible new resonant states in a background free environment (bb, W + W - &  +  - decays); (see: KMR EPJC23(2002)311) Higgs glueballs quarkonia 0 ++ (  b ) gluinoballs invisible decay modes of Higgs (and SUSY)!? CP-odd Higgs Squark & gluino thresholds are well separated practically background free signature: multi-jets & E T 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 GeV(S.Raby) Events with isolated high mass  pairs Moreover: Mini-Black Holes, Extra Dimensions – The Brane World !!!... (see: Albrow and Rostovtsev) - XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

9 Probing Very Small-x Gluons Instrument region with tracking, calorimetry (em+had), muons, jets, photons... In SD: If a pair of high E T jets are produced, then: If the interacting partons have fractional momenta  of P, then  =x Bj / , then (if all hadrons i in the event are measured): Consider a high momentum proton: Measure gluon distribution G(x,Q 2 ) at fixed Q 2 and small x with x››Q  probe gluons with the transverse size = |  b|~1/Q and longitudinal size = |  z|~1/px.  gluon saturation, colour-glass condensates, colour-dipoles,.... XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

10 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. J PC = 0 ++ (2 ++, 4 ++,...) Gap Jet+Jet      min  max Survival of the rapidity gaps? 1 see: DKMOR EPJC25(2002)391 Measure the parity P = (-1) J : d  /d   1 + cos2  Mass resolution  S/B-ratio M X 2  1  2 s Also: Jet energy scale calibration? – M. Albrow XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

11 Signatures Proton (Roman Pots): elastic proton (  *=1540m: 5   -t  1 GeV 2,  *=18m: 3   -t  10 GeV 2 ) diffractive proton (  *=1540m: 90% of all diffractive protons:   & -t  GeV 2 ) hard diffractive proton (  * = 0.5m: excellent coverage in  -t space) Rapidity Gap (T1 & T2, Castor & ZDC): rapidity gaps (up to L~ cm -2 s -1 : 3  |  |  7, +veto counters?) Very Fwd Objects (T1 & T2, Castor & ZDC): Jets (up to L~ cm -2 s -1 : 3  |  |  7, +veto counters?) , e,  (fwd em calorimetry & muons: 3  |  |  7) tracks (vx constraints & pattern recognition: 3  |  |  7) particle ID? Correlation with CMS Signatures (central jets, b-tags,...) XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

12 Correlation with the CMS Signatures e, , , , and b-jets: tracking: |  | < 2.5 calorimetry with fine granularity: |  | < 2.5 muon: |  | < 2.5 Jets, E T miss calorimetry extension: |  | < 5 High p T Objects Higgs, SUSY,... Precision physics (cross sections...) energy scale: e &  0.1%, jets 1% absolute luminosity vs. parton-parton luminosity via ”well known” processes such as W/Z production? XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

13 Leading Protons Extended Coverage of Inelastic Activity CMS To Reach the Forward Physics Goals Need: XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

14 Leading Protons - Measurement RP1 RP2 RP3 220 m 180 m 147 m IP5CMS Interaction Point TAS Beam Absorber for secondaries between the IP and Q1 Qi Quadrupole Magnets TASA Beam Absorber for secondaries between Q1 and Q2 TASB Beam Absorber for secondaries between Q2 and Q3 DFBxCryogenic Electrical Feed-Boxfor Arc Di Dipole Magnet i TAN Beam Absorber for neutral secondaries before Q1-Q3 BSRSynchrotron Radiation Observation System TCL Long Collimator for protecting Quadrupole Magnets The small-angle protons are detected within the LHC beam pipe at large distances from the IP. To facilitate detection of elastically and diffractively scattered protons, special machine optics are needed   * = 1540m (-t down to  GeV 2 ), 18m (-t up to  10 GeV 2 ) For hard diffraction and low-x physics, nominal – high luminosity – conditions are required   * = 0.5m RPi: Special insertion devices needed for placing the proton detectors within the beam pipe  Roman Pots CMS XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

15 Leading Proton Detection-An Example 147m180m220m0m308m338m m        IP Q1-3 D1 D2Q4Q5Q6Q7B8Q8B9Q9B10B11Q10     Helsinki group: Jerry Lamsa & RO  = 0.02 Note the magnification x vs. z! XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

16 Pomeron exchange ~ e –B|t| diffractive structure Photon - Pomeron interference   L dt = and cm -2 pQCD ~ |t| –8 Elastic Scattering: d  /dt d  /dt (mb/GeV 2 ) -t (GeV 2 ) -t min ~ 2 · GeV 2 -t max ~ 10 GeV 2 extrapolate to – t = 0! XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

17 Coulomb region  5  [lower s, RP closer to beam] Interference,  meas. 5   5  [as above], standard  * = 1540 m Pomeron exchange 5   0.1  * = 1540 m Diffractive structure 0.1  1  * = 1540 m, 18 m Large |t| – perturb. QCD 1  10  * = 18 m Region |t| [GeV] 2 Running Scenario Elastic Scattering: Acceptance in -t XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

18 Extrapolation of Elastic Cross-Section to t = 0 EffectExtrapolation uncertainty Statistics ):10 7 events 0.07 % Uncertain functional form of d  /dt 0.5 % Beam energy uncertainty0.05 %0.1 % Beam / detector offset20  m0.08 % Crossing angle0.2  rad0.1 % Total0.53 % Non-exponential d  /dt fitted to Slope parameter according to BSW Model see: KMRO EPJ(2001)313 XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

19 ~ 90 % of all diffractive protons are seen in the Roman Pots -assuming  =  p/p can be measured with a resolution of ~ 5 x Soft Diffractive Protons (high  *) A < 5 % A > 95 % %  * = 1540 m XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

20 Hard Diffraction (high  *): Acceptance XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

21 Measurement of  tot -Luminosity-independent measurement of the total cross-section by using the Optical Theorem: Measure the elastic and inelastic rate with a precision better than 1%. Extrapolate the elastic cross-section to t = 0. Or conversely: Extract luminosity: XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

22 T1: 3.1 <  < 4.7 T2: 5.3 <  < 6.5 T1 T m ~14 m CASTOR Need Extension to Inelastic Coverage To measure the colour singlet exchange, need to extend central detector coverage in the forward direction:  > 5. XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

23 Measurement of the Total Rate N el + N inel  [mb] T1/T2 double arm trigger loss [mb] T1/T2 single arm trigger loss [mb] Uncertainty after extrapolation [mb] Minimum bias Single diffractive Double diffractive Double Pomeron1~ 0.2 (using leading p and CMS) 0.02 Elastic Scattering Acceptance single diffraction simulated extrapolated detected Loss at low masses Extrapolation of diffractive cross-section to large 1/M 2 using d  /dM 2 ~ 1/M 2. Total: 0.8 %  50% acceptance down to 3.5 (1.5) GeV Model uncertainties are large! XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

24 Accuracy of  tot Extrapolation to t = 0 Total rate N el + N inel  = 0.12 ± 0.02 XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

25 Total Cross Section - TOTEM TOTEM  tot  (lns)  as s    = 0, 1, 2, or ?? XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

26 Elastic Scattering- TOTEM TOTEM XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

27 Diffractive Mass Acceptance TOTEM ’base line’ +veto counters XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

28 Towards Hard Diffraction - Tevatron results jets, heavy quarks, heavy bosons produced at ~ 1% of the inclusive rate XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

29 Running Scenarios Scenario (goal) 1 low |t| elastic,  tot, min. bias 2 diffractive physics, large p T phenomena 3 intermediate |t|, hard diffraction 4 large |t| elastic  * [m] N of bunches Half crossing angle [  rad] Transv. norm. emitt. [  m rad] N of part. per bunch 0.3 x x x RMS beam size at IP [  m] RMS beam diverg. [  rad] Peak luminosity [cm -2 s -1 ] 1.6 x x ( ) x x Runs at  * = 0.5 m, L = (10 33  ) cm -2 s -1 foreseen as an extension to the TOTEM program. XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

30 Exciting new physics potential in the process: pp  p  (J PC =0 ++ )  p p p jet   p p p p jet P P -Colour singlet exchange process with exclusive priviledges - J PC selection rule  e + e - ILC type threshold scan for new physics! see: KMR EPJ(2002) - Need to solve the L1 trigger issue at high luminosity (pile-up) conditions. XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

31 Exclusive Production by CED: Examples Advantage: Selection rules: J P = 0 +, 2 +, 4 + ; C = +1  reduced background, determination of quantum numbers. Good  resolution in TOTEM: determine parity: P = (-1) J+1  d  /d  ~ 1  cos 2  Particle  excl Decay channelBR Rate at 2x10 29 cm -2 s -1 Rate at cm -2 s -1 (no acceptance / analysis cuts)  c0 (3.4 GeV) 3  b [KMRS]  J/     +  –  +  – K + K – 6 x / h 46 / h 62 / h 1900 / h  b0 (9.9 GeV) 4 nb [KMRS]    +  – / d3 / d H (120 GeV) 3 fb (  2.5fb) bb / y1 / y Need L ~ cm -2 s -1 for Higgs, i.e. a running scenario for  * = 0.5 m: try to modify optics for enhanced dispersion, try to move detectors closer to the beam, install additional Roman Pots in cold LHC region at a later stage. XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

32 Hard Diffractive Protons (Low  *) CMS Dispersion in horizontal plane (m) xx Optical function  in x and y (m) For a 2.5 mm offset of a   0.5 % proton, need dispersion  0.5 m.  Proton taggers to be located at > 250 m from the IP (i.e. in a ”cryogenic section” of the LHC). yy DxDx horizontal offset =  D x (  = momentum loss) XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

33 Dispersion suppressorMatching section Separation dipolesFinal focus Potential locations for measuring the leading protons in pp  p  X  p with M X ~ O(100 GeV). 420 m220 mCMS(308/338m) Cryogenic (”cold”) region (with main dipole magnets) locations of currently planned TOTEM pots!! XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

34 Leading protons: Hard Central Diffraction Uncertainties included in the study: Initial conditions at the interaction point Conditions at detector location Position resolution of detector (  x,y = 10  m) Resolution of beam position determination (  x,y = 5  m) Off-sets at detector locations pp  p + X + p simulated using PHOJET1.12& ExHuME Protons tracked through LHC6.2& 6.5 optics using MAD Transverse vertex position (  x,y = 11  m) Beam energy spread (  E = ) Beam divergence (   = 30  rad) J.Lamsa, T. Maki, R.Orava, K.Osterberg...

35 Acceptance: ExHuME vs. PHOJET 50% 33% " " calculation: either both protons are detected at 420m, or both protons are detected at 220m, or one proton is detected at 420 [220]m with the other one detected at 220 [420]m. 24% 12% XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava see Marek Tasevsky’s talk on Monday

36 Resolution: ExHuME vs. PHOJET ExHuME m ExHuME 420m PHOJET 420m PHOJET m 2.8% 0.9% 3.7% Helsinki group: J.Lamsa (parametrisations of the MAD simulation results of T. Mäki by RO) 420m+220m ExHuME 420m ExHuME 420m+220m PHOJET 420m PHOJET Helsinki group: Jerry Lamsa et. al. XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava

37 TOTEM Physics Scenarios Proton  * (m) rapidity gap L(cm -2 s -1 ) jetinelastic activity ,e, ,  ,  ++,... elastic scattering total cross section soft diffraction hard diffraction ’1540’ ’18’  ’1540’ ’1540’ ’170’ ’ 0.5’ low-x physics exotics (DCC,...) CED Higgs, SUSY,... central pair central & fwd inelastic acceptance gap survival jet acceptance di-jet backgr b-tag, , J/ , TOTEM & CMS TOTEM & CMS TOTEM & CMS central & fwd jets di-leptons jet-  mini-jets resolved?  ± vs.  o multiplicity leptons  ’ s  jet anomalies? W, Z, J/ ,... , K ±,,... ’0.5’ ’170’ ’0.5’ ’170’ ’0.5’ mini-jets? beam halo? trigger XXXV ISMD 2005, KROMĚŘÍŽ, CZECH Risto Orava