p. 1Mario Deile – Physics at LHC Mario Deile CERN PH-TOT Diffractive Physics: What answers do we expect from the LHC? DinoGoulianos

p. 2Mario Deile – ~30 mb ~10 mb ~7 mb ~1 mb M M Double Pomeron Exchange Double Diffraction Single Diffraction Elastic Scattering ~65 mb ~ 58 % << 1 mb Dominant Event Classes in p-p Collisions ~ 42 % Processes with large cross-sections!

p. 3Mario Deile – Signatures of Diffractive Events By rapidity gap: Reconstruct proton momentum loss  =  p/p from diffractive system X (inelastic component): or from rapidity gap:  needs good rapidity coverage By leading protons: needs detectors in beam-pipe insertions far from IP close to the beam (e.g. Roman Pots, moving beam pipes etc.); Already done at ISR, SppS, HERA, RHIC, Tevatron. Particularly strong focus on leading proton measurement at LHC. Roman Pots on both sides of the IPs. X (M X 2 =  1  2 s) Rapidity Gap -ln  2 Rapidity Gap -ln  1  DPE  X (M X 2 =  s) Rapidity Gap -ln   SD p

Mario Deile – LHCf 0m 6m 14m 16m 140m m 420m, ~7 km LHC Experiments: Pseudorapidity Acceptance FP420, IR 3 0m 17m 140m 220m 240m 420m FP420 ALFA (RP240): vertical Roman Pot with scintillating fibres for absolute lumi. meas. LHCf: tracker and calo for forward n,  ,  RP220 project for diffraction: vert. RP and movable beampipe LUCID: Cerenkov tubes for relative lumi. calib. CASTOR: calorimeter (initially on 1 side of IP5) T2: GEM tracker HF: calorimeter T1: CSC tracker TOTEM Roman Pots: horizontal and vertical with ‘edgeless’ Si detectors

p. 5Mario Deile – ALICE: diffractive gap trigger No Roman Pots, but Zero Degree Calorimeter for neutral particles. Identify diffractive events by their rapidity gap and leading neutrals from N * excitations. See presentation on ALICE diffractive physics programme by R. Schicker.

p. 6Mario Deile – Typical range of model predictions: 90 – 130 mb. Aim of TOTEM / ATLAS at the LHC: ~ 1 – 2 % accuracy Total p-p Cross-Section [PRL (2002)] COMPETE: Disagreement E811–CDF: 2.6  ~ ln 2 s or ~ s 0.08 or ~ ln s ? “radius increases”

p. 7Mario Deile –  = fine structure constant  = relative Coulomb-nuclear phase G(t) = nucleon el.-mag. form factor = (1 + |t| / 0.71) -2  = Re / Im T elastic,nuclear (t = 0) Coulomb scattering Nuclear scattering Coulomb-Nuclear interference Total Cross-Section and Elastic Scattering at low |t| Optical Theorem:

p. 8Mario Deile – Total Cross-Section and Elastic Scattering at low |t| TOTEM Approach: Measure the exponential slope B in the t-range GeV 2, extrapolate d  /dt to t=0, measure total inelastic and elastic rates (all TOTEM detectors provide L1 triggers): Optical Theorem:  = fine structure constant  = relative Coulomb-nuclear phase G(t) = nucleon el.-mag. form factor = (1 + |t| / 0.71) -2  = Re / Im T elastic,nuclear (t = 0) Coulomb scattering Nuclear scattering Coulomb-Nuclear interference

p. 9Mario Deile – Total Cross-Section and Elastic Scattering at low |t| TOTEM Approach: Measure the exponential slope B in the t-range GeV 2, extrapolate d  /dt to t=0, measure total inelastic and elastic rates (all TOTEM detectors provide L1 triggers): ATLAS Approach: Measure d  /dt down into Coulomb region and use el.-mag. cross-section for normalisation Optical Theorem:  = fine structure constant  = relative Coulomb-nuclear phase G(t) = nucleon el.-mag. form factor = (1 + |t| / 0.71) -2  = Re / Im T elastic,nuclear (t = 0) Coulomb scattering Nuclear scattering Coulomb-Nuclear interference

p. 10Mario Deile – Elastic pp Scattering at 14 TeV: Model Predictions Big uncertainties at large |t|: Models differ by ~ 3 orders of magnitude! TOTEM will measure the complete range with good statistics 3-gluon exchange at large |t|: Islam Model:  * = 90 m  * = 2 m  * = 1540 m  * = 2625 m (ATLAS)

p. 11Mario Deile – Detection of Diffractively Scattered Protons TOTEM: Proton Acceptance in (t,  ): (contour lines at A = 10 %) RP220  = 0.5m - 2m (x *, y * ): vertex position (  x *,  y * ): emission angle  =  p/p Transport equations: 10  x(mm)‏ x [mm] horizontal Si detector vertical Si detector vertical Si detector y [mm] Example: Hit TOTEM RP220 with  * = 90m t ~ -p 2  * 2   = 1540 m L = – 2 x % of all p seen; all    = 90 m L = – 3 x % of all p seen; all    = 0.5 – 2 m L = – p with  seen; all t Optics properties at RP220:  resolved

p. 12Mario Deile –  Diffraction at  * = 0.5 – 2 m with high Luminosity FP420 RP220 FP420 Project (IP1 and IP5) RP147 Protons seen for  > 2.5 % lg(  ) lg (-t [GeV 2 ]) movable beampipe: 3D Si trackers and timing detectors Alternative idea: put detectors in momentum cleaning region IR3 (  talk by K. Eggert)

p. 13Mario Deile – Measurement of Diffractive Cross-Sections Aim: measurement of all kinematic variables and their correlations. Single Diffraction: (Regge theory) Pomeron flux in proton ~ e b t /  1+2  Pomeron-proton cross-section ~ (s  )   and t dependence experimentally confirmed up to Tevatron, but total SD cross-section lower. [K. Goulianos: Phys. Lett. B 358] Regge pM t  At 14 TeV? Slope parameter at LHC: b ~ 5 – 7 GeV -2 ?  distance of diffractive interaction R ~ 0.5 fm p p Difficulty in Single Diffraction: Mass from proton measurement:  ~ 2 x (principally limited to by beam energy spread!)  Mass resolved for  > 450 GeV  need to calculate M directly from diffractive system

p. 14Mario Deile – Rapidity Gap vs. Proton Momentum Example: Single Diffraction measured with   = 90 m (protons with all  detected). Proton momentum resolution:   = 90 m:  p (  ) = 1.6 x Rapidity gap measurement resolution:  (  ) =  0.8 – 1 Compare the proton momentum loss  with the rapidity gap  : verify  = –ln  proton  M proton resolution limited by LHC energy spread gap edge in T1, T2 gap edge in CMS gap edge in T1, T2 via proton (  * =90m)   = –ln   = 100% gap edge  range M (SD) [GeV] < 1 x < 5proton seen,  not resolved, gap not meas., detectors empty 1 x – 1.6 x – 450 proton seen,  not resolved, gap measured 1.6 x – – 3000  measured, gap measured > 0.045> 3000  measured, gap not seen, detectors full ZDC

p. 15Mario Deile – shape of function F D similar normalisation different (factor 10) difference related to (soft) rescattering effects between spectator partons Rapidity Gap Survival in Hard Diffraction  IP Q2Q2 t ** e e’ pp’ IP Rap. Gap jet  hard scattering Diffractive DIS at HERA gap survival probability Tevatron hard scattering cross-section diffractive structure function

p. 16Mario Deile – Rapidity Gap Survival Probability: 2 gaps vs 1 gap R(SD/ND) R(DPE/SD) Suppression similar for 2 gaps and 1 gap

p. 17Mario Deile – Central Diffraction (DPE) M PP 2 =     s ; normalised DPE Mass Distribution (acceptance corrected) 14  b / GeV 1.4 nb / GeV  50 events / (h cm -2 s -1  sufficient statistics to measure the inclusive mass spectrum   =90m:  (M) = 20 – 70 GeV 5-dimensional differential cross-section: Any correlations? Mass spectrum: change variables (  1,  2 )  (M PP, y PP ):  (M) = 20 – 70 GeV  (M)/M = 2 %

p. 18Mario Deile – Central Production clean signature and redundancy: measure both protons and central system exchange of colour singlets with vacuum quantum numbers  Selection rules for system X: J PC = 0 ++, (2 ++, 4 ++ ) Study the kinematic properties of exclusive production (e.g. t-spectrum and p T distrib. of X), compare with inclusive production (M = X + ?) High gluon fraction in Pomeron (measured by HERA, Tevatron)  Use the LHC as a gluon-gluon collider and look for resonances in d  /dM Special Case: Exclusive production X = , jj,  c0,  b0, H, SUSY H, glueballs? seen at the Tevatron

p. 19Mario Deile – Exclusive Production: Examples System M  excl Decay channelBR Events at L int = 0.3 pb -1 Events at L int = 0.3 fb -1  c0 (3.4 GeV) 3  b [KMRS]  J/     +  –  +  – K + K – 6 x 10 – x 10 6  b0 (9.9 GeV) 4 nb [KMRS]    +  –  1.5x10 -3  0.5  500 jj (     > 1, E > 50 GeV) 0.2 nb  (E > 5 GeV) 600 fb Predictions for the LHC:   = 90 m L = – 3 x   = 0.5 – 2 m L = – 10 34

p. 20Mario Deile – Other Central Production Processes  systems with C = P = – 1 : e.g. J/  Y Pomeron – Photon fusionPomeron – Odderon fusion Odderon = hypothetical analogon to Pomeron with C = -1 QCD: Pomeron = 2 gluons, Odderon = 3 gluons See Photon/Odderon studies by Alice.

p. 21Mario Deile – Detection of Central Production Ideal scenario: reconstruct kinematics from protons AND resonance decay products (  redundancy!) But: Only possible for small production rapidities y i.e. symmetric events     M PP 2 =     s L = < 3 x too low for  b, H  J/     +  –  +  – K + K –    +  –

p. 22Mario Deile – Detection of Central Production Ideal scenario: reconstruct kinematics from protons AND resonance decay products (  redundancy!) But: Only possible for small production rapidities y i.e. symmetric events     M PP 2 =     s  J/     +  –  +  – K + K –    +  –

p. 23Mario Deile – Diffractive Higgs Production Difficulty of diffraction at high luminosity: Pile-up of several events per bunch crossing; L = 1 x : 35 events / bunch crossing Combinations faking DPE signature: e.g. (single diffraction) + (non-diffractive inelastic) + (single diffraction)  Leading protons and central diffractive system have to be matched: timing measurements in leading proton detectors (10 – 20 ps in FP420)  z(vertex) Events / 1 GeV Invariant mass calculated from the two protons Various Higgs studies: SM with m H = 120 GeV:  x BR (H  bb) = 2 fb, S/B ~ 1 MSSM M h max scenario (m A = 120 GeV, tan  = 40)  x BR (h  bb) = 20 fb NMSSM scenario (m h = 93 GeV, m a = 10 GeV)  x BR (h  aa  4  ) = 4.8 fb but S/B  10 ! L int = 60 fb -1  t = 10 ps MSSM [JHEP 0710:090,2007]

p. 24Mario Deile – Summary: Questions on diffraction addressed by the LHC Total p-p cross-section measurement on the ~1% level Differential elastic cross-section measured over 4 orders of magnitude in t with very different scattering mechanisms Event topologies and differential cross-sections of diffractive processes (Tools: leading proton detectors, different specially designed beam optics, good rapidity coverage) Rapidity gap studies based on proton tagging Study of central production with search for resonances: inclusive vs exclusive processes

p. 25Mario Deile –

p. 26Mario Deile –

p. 27Mario Deile – CMS+TOTEM Forward Detectors ~14 m T1:  3.1 <  < 4.7 CSC trackers T2: 5.3 <  < 6.5 GEM trackers 10.5 m T1 T2 HF Symmetric experiment: RPs on both sides!  Unique tool for diffraction Roman Pots: RP220 RP147 CASTOR calorimeter ZDC

p. 28Mario Deile – 90% (65%) of all diffractive protons are detected for  * = 1540 (90) m largest acceptance detector ever built at a hadron collider CMS + TOTEM: Acceptance CMS central T1 HCal T2 CASTOR   =90m RPs   =1540m ZDC  = - ln tg  /2 Roman Pots T1,T2 Roman Pots Charged particles Energy flux dN ch /d  dE/d  CMS

p. 29Mario Deile – Leading Proton Detection: TOTEM Roman Pots Roman Pot Unit Leading proton detection at distances down 10  beam + d Need “edgeless” detectors (efficient up to physical edge) to minimise width d of dead space. TOTEM: specially designed silicon strip detectors (CTS), efficient within 50  m from the edge “edgeless” Si strip detectors (10 planes per pot) Horizontal Pot Vertical Pot BPM

p. 30Mario Deile – Leading Proton Detection: FP420 (IP1 and IP5) and ATLAS RP220 Mechanical design based on movable “Hamburg Pipe”: Proton spectrometers proposed: at 220m and ~420 m from IP1 and at ~420m from IP5 Two (or three) stations for each spectrometer Two pockets for each station: tracking and timing detectors Mobile Plate Gastof Maxon Motor Si Box Moving Pipe Fix Plate LVDT Mechanical stop Si Detector mm STATION Pockets

p. 31Mario Deile – New Idea: Proton Measurement in IP3 Acceptance in Momentum Loss  Detects protons from all interaction points.

p. 32 PMTs LUCID: Cerenkov tubes at |z| ~17 m (5.4< |  | <6.1) for relative lumi. calib. LUCID ZDC ALFA (RP240): vertical Roman Pot with scintillating fibres for absolute lumi. meas. ATLAS + LHCf Forward Detectors RP220 project for diffraction: vert. RP and movable beampipe LHCf: tracker and calo for forward n,  ,  Beam pipe

p. 33Mario Deile – PMT baseplate optical connectors scintillating fibre detectors glued on ceramic supports 10 U/V planes overlap & trigger Roman Pot MAPMTs FE electronics & shield Roman Pot Unit The Experiments: ALFA (IP1) 240 m ATLAS ALFA RP Same configuration on the other side of IP1

p. 34Mario Deile – The Experiments: LHCf (IP1) scintillators tungsten layers scintillating fibers Silicon layers scintillators tungsten layers Arm 1 Arm 2 TAN TAN 140m

p. 35Mario Deile – Characteristics of Diffractive Events P(  ) = e - ,  = dn/d  Exchange of colour: Initial hadrons acquire colour and break up. Rapidity gaps filled in hadronisation  Exponential suppression of rapidity gaps: Non-diffractive events: Exchange of colour singlets with vacuum quantum numbers (“Pomerons”)  rapidity gaps  with P(  ) = const. Many cases: leading proton(s) with momentum loss  p / p     typically  Diffractive events: p p p p P P     p p g g

p. 36Mario Deile – ~1.5 GeV 2 Elastic Scattering - from ISR to Tevatron exponential slope B at low |t| increases: B ~ R 2 ~ 0.7 GeV 2 ~ 1.7 GeV 2 exponential region ds/dt ~ e -B|t|

p. 37Mario Deile – Diffractive minimum: analogous to Fraunhofer diffraction: |t|~p 2  2 Elastic Scattering - from ISR to Tevatron exponential slope B at low |t| increases

p. 38Mario Deile – ~1.5 GeV 2 Diffractive minimum: analogous to Fraunhofer diffraction: |t|~p 2  2 Elastic Scattering - from ISR to Tevatron ~ 0.7 GeV 2 ~ 1.7 GeV 2 exponential slope B at low |t| increases minimum moves to lower |t| with increasing s  interaction region grows (as also seen from  tot ) depth of minimum changes  shape of proton profile changes depth of minimum differs between pp, pˉp  different mix of processes

p. 39Mario Deile – |t| = 6.5 x GeV 2 Coulomb – nuclear cross-over point Elastic Scattering Acceptance 1.3 mm 6 mm Detector distance from beam centre ATLAS:    = 2625 m TOTEM: better extrapolation lever arm with  * = 1540 m than with  * = 90 m. Expected uncertainty in  tot : ~ 1% ~ 5% ATLAS: Expected uncertainty in  tot : ~ 2% if Coulomb region can be reached. Measurements down to lowest |t| need reduced beam emittance and very close detector approach to the beam  difficult  *=1540 m  *=2 m  *=90 m log(-t / GeV 2 ) GeV GeV GeV 2 Acceptance TOTEM:  * = 1540 m, 90 m, 2 m Acceptance for elastically scattered protons depends on machine optics (  * )

p. 40Mario Deile – Measurement of  =  f(0) /  f(0)  is interesting for  tot : prediction of  tot at higher s via dispersion relation: COMPETE Prediction for LHC: Try to reach the interference region: move the detectors closer to the beam than 10  mm run at lower energy  s = 2p < 14 TeV: |t| min = p 2  2  * =1540m,   =1mm rad asymptotic behaviour:  1 / ln s for s  

p. 41Mario Deile –  el /  tot ~ 30% at the LHC ?  el /  tot = 50% : black disk limit The proton not only grows but becomes blacker. Saturation? Elastic and Diffractive Fractions of  tot dependence on  tot,  el SD / total ratio observed to decrease. At 14 TeV? Various models:

p. 42Mario Deile – diffractive vs proton PDF’s: larger gluon content harder gluon structure proton PDF’s diffractive PDF’s u,d,s Interpretation of diffractive PDF’s

p. 43Mario Deile – Measurement of Resonances Ideal scenario: reconstruct kinematics from protons AND resonance decay products (  redundancy!) But: Only possible for small production rapidities y i.e. symmetric events     M PP 2 =     s L = < 3 x too low for  b, H  J/     +  –  +  – K + K –    +  – 110  3 H (120 GeV) Rapidity y 110  3 cc bb

p. 44Mario Deile – Measurement of Resonances Ideal scenario: reconstruct kinematics from protons AND resonance decay products (  redundancy!) But: Only possible for small production rapidities y i.e. symmetric events     M PP 2 =     s 110  3  J/     +  –  +  – K + K –    +  – Rapidity y 110  3 cc bb H (120 GeV)

p. 45Mario Deile – Higgs (SM, MSSM) tan  = 30tan  = 50 m A  x BR (A  bb) 130 GeV 0.07 fb 130 GeV 0.2 fb m h  x BR (h  bb) GeV 5.6 fb GeV 13 fb m H  x BR (H  bb) GeV 8.7 fb GeV 23 fb MSSM Examples: m A = 130 GeV m A = 100 GeV tan  = 30tan  = 50 m A  x BR (A  bb) 100 GeV 0.4 fb 100 GeV 1.1 fb m h  x BR (h  bb) 98 GeV 70 fb 99 GeV 200 fb m H  x BR (H  bb) 133 GeV 8 fb 131 GeV 15 fb [from A. Martin] SM with m H = 120 GeV:  x BR (H  bb) = 2 fb 30 fb -1,  m = 3 GeV: S/B = 11/10  x BR (H  WW*) = 0.4 fb 30 fb -1 : S/B = 8/3 MSSM: