1. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 1 LHC Forward Physics Jim Whitmore Penn State University Experiments: ALICE ATLAS CMS FP420 (R&D project) LHCf TOTEM

2. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 2 LHC Forward Physics Total cross-section (and luminosity) with a precision of 1% Elastic pp scattering in the range: 10 -3 < |t| = (p  ) 2 < 10 GeV 2 Forward Physics: Low-x dynamics Diffractive phenomena: Soft and Hard Inclusive and exclusive Double Pomeron Exchange (DPE) Leading particle and energy flow in the forward direction pA, AA,  and  p processes (sorry, I will not cover these topics) Many of these topics can be studied best at startup luminosities

3. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 3 +TOTEM +LHCf +FP420 “We are not studying a possibility of forward physics with LHCb at the moment”

4. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 4 General philosophy: Additional detectors near the IP Proton (Roman Pot) detectors: want to detect small scattering angles (~few  rad:) and the beam divergence so want large values of  *. However, luminosity want small  * So expect a selection of  * values (0.5-1540 m) RP detectors at 140-220 m from IP Need to go to 420 m → the “cold” region Forward Detectors

5. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 5 Roman Pot acceptance Low  *: (0.5m): Lumi 10 33 -10 34 cm -2 s - 1 220m: 0.02 <  < 0.2 300/400m: 0.002 <  < 0.02 Detectors in the 420 m region are needed to access the low  values TOTEM (ATLAS) FP420 - 240 m M2=12sM2=12s  = proton momentum loss =  p/p Reconstruct  with roman pots  < 0.1  O(1) TeV “Pomeron beams“ (A. deRoeck)

6. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 6 T1:  3.1 <  < 4.7 T2: 5.3 <  < 6.5 T1 T2 CASTOR (CMS) RP1 (147 m) RP2 (180 m) (later option) RP3 (220 m) Experimental Apparatus 10.5 m ~14 m TOTEM + CMS CMS Castor 5.25<  <6.5 IP5

7. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 7 ~3 m 5 planes with measurement of three coordinates per plane. 3 degrees rotation and overlap between adjacent planes Primary vertex reconstruction Trigger with CSC wires T1 Telescope 3.1< |  | <4.7 T2 Telescope Digital r/o pads Analog r/o circular strips 5.3< l  l < 6.5 GEM (Gas Electron Multiplier) Telescope: 10 ½ -planes 13.5 m from IP

8. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 8 Roman Pot unit: - Vertical and horizontal pots mounted as close as possible - TOTEM at the RP:  beam ≈ 80  m - Leading proton detection at distances down to 10  beam + d - Need “edgeless” detectors that are efficient up to the physical edge to minimize “d” - Currently two tech. (5-10  m and 40-50  m dead areas) 0 reconstructed track Tracks Roman Pots Test beam data: RP in SPS beam and the detector is measuring the halo u,v info reconstructed tracks in y BPM

9. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 9 Forward Detectors in ATLAS IP1 Roman Pots at 240 m Cerenkov Counter (LUCID) = a lumi monitor at 5.4 <  < 6.1 + neutral energy at zero degrees (I. Efthymiopoulos)

10. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 10 Scenario Physics: 1 low |t| elastic,  tot, min. bias, soft diffraction 2 diffraction 3 large |t| elastic 4 hard diffraction large |t| elastic (under study)  * [m]1540 1890 N of bunches431562808156 N of part. per bunch (x10 11 ) 0.30.6 - 1.151.15 Half crossing angle [  rad] 001600 Transv. norm. emitt. [  m rad] 11 - 3.753.75 RMS beam size at IP [  m] 454454 - 88095200 RMS beam diverg. [  rad]0.290.29 - 0.575.282.4 Peak luminosity [cm -2 s -1 ]1.6 x 10 28 2.4 x 10 29 3.6 x 10 32 2 x 10 30 Running Scenarios TOTEM (V. Avati, M. Deile)

11. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 11 pp total cross section and luminosity monitor TOTEM-CMS ATLAS

12. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 12 pp total Cross-Section Measure the total rate (N el +N inel ),  diff ~ 18 mb and min. bias ~65 mb, with an expected precision of 0.8 % (running for 1 day at L = 1.6 x 10 28 cm -2 s -1 ). Extrapolate the elastic cross-section to t = 0: systematics dominated: 0.5 % (statistical error after 1 day: 0.07 %) ρ = Re f(0)/Im f(0) unknown; using COMPETE pred.: 0.2 % 1 % (  = 0.1361±0.0015 +0.0058 -0.0025 ) pp total cross section Luminosity-independent measurement using the Optical Theorem : (M. Deile)

13. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 13 Current models predictions: 90-130 mb Aim of TOTEM: ~1% accuracy (~1 mb) LHC: COMPETE Collaboration fits all available hadronic data and predicts: pp total Cross-Section [PRL 89 201801 (2002)] Cudell et al.

14. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 14 ATLAS’s Plans: ATLAS submitted a Letter of Intent to complement the experiment with a set of forward detectors for luminosity measurement and monitoring as part of a two stage scenario: 1.Short time scale  Roman Pots at 240 m from IP1 Probe the elastic scattering in the Coulomb interference region  Dedicated detector for luminosity monitoring – LUCID Used also to transfer the calibration from 10 27  10 34 Goal: Determine absolute luminosity at IP1 (2-3% precision) 2. Longer time scale  Study opportunities for diffractive physics with ATLAS  Propose a diffractive physics program using additional detectors (I. Efthymiopoulos)

15. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 15 Physics interest -- ATLAS Luminosity Measurement – Why? Important for (precision) comparison with theory:  e.g.  bb,  tt,  W/Z,  n-jet, … cross-section deviations from SM could be a signal for new physics Systematic error dominated by the luminosity measurement (ATLAS-TDR-15, May 1999) (I. Efthymiopoulos)

16. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 16 pp elastic scattering TOTEM

17. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 17 ~1.5 GeV 2 Elastic scattering – from ISR to Tevatron

18. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 18  * = 1540 m L = 1.6 x 10 28 cm -2 s -1 (1) 10 4 per bin of 10 -3 GeV 2 diffractive structure Photon - Pomeron interference   pQCD pp 14 TeV BSW model Multigluon (“Pomeron”) exchange  e – B |t| -t [GeV 2 ]  t  p 2  2 d  /dt [mb / GeV 2 ] ~1 day (1) (3) wide range of predictions pp elastic scattering cross-section  * =18 m L = 3.6 x 10 32 cm -2 s -1 (3) ~ 1/|t| 8 BSW = Bourrely, Soffer and Wu B(s) = B 0 + 2  P ’ ln (s/s 0 ) ~ 20 GeV -2 at LHC

19. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 19 Observations: fwd diffraction cross section increases diffractive peak shrinks interference dip moves to smaller t at –t  1 GeV 2: d  /dt  1/t 8 (3-gluon exchange) little  s dependence Elastic Scattering Models (eg. Islam et al)  1/t 8 BSW Desgrolard et al Islam et al

20. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 20 0.375 R el =  el (s)/  tot (s) R diff =[  el (s) +  SD (s) +  DD (s)] /  tot (s)  0.30  el  30% of  tot at the LHC ?   SD +  DD  10% of  tot (= 100-150mb) at the LHC ? 0.2 0.4 0.3 0.2 0.3 0.1 Elastic Scattering-  el /  tot 3 45 34 6 5 6 log(s/s 0 ) (M. Deile)

21. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 21 Low-x at the LHC LHC: due to the high energy can reach small values of Bjorken-x in structure of the proton F(x,Q 2 ) Processes:  Drell-Yan  Prompt photon production  Jet production  W production If rapidities below 5 and masses below 10 GeV can be covered  x down to 10 -6 -10 -7 Possible with T2 upgrade in TOTEM (calorimeter, tracker) 5<  < 6.7 ! Proton structure at low-x !! Parton saturation effects? (A. deRoeck)

22. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 22 Diffractive physics ALICE TOTEM CMS F420 project

23. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 23 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 (M. Ruspa)

24. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 24 90% (65%) of all diffractive protons are detected for  * = 1540 (90) m largest acceptance detector ever built at a hadron collider Roman Pots TOTEM+CMS T1,T2 Roman Pots dN ch /d  dE/d  Total TOTEM/CMS acceptance CMS central T1 HCal T2 CASTOR   =90m RPs   =1540m ZDC Pseudorapidity:  = ln tg  /2 Energy flux Charged particles CMS + TOTEM: Acceptance 10 7 min bias events, incl. all diffractive processes, in 1 day with  * =1540 m

25. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 25 Soft Diffractive Event rates DPE: pp  pXp Acc = 27.8% for detecting both protons (  * = 90 m) ALICE is studying the possibility of implementing a trigger requiring a rapidity gap on both sides of a central region of 1.5 units of rapidity. The selection can include EM energy deposition in the PHOS, protons in the HMPID (RICH), or electrons identified with the TRD, opening the possibility to study heavy flavour production in double diffractive events.

26. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 26 Measure > 90 (65)% of leading protons with RPs at  * = 1540 (90) m and diffractive system X with T1, T2 and CMS. Events/GeV-day DPE Scenario (2) (4)  * (m) = 1540 90 Exchange of color singlets (“Pomerons”)  rapidity gaps  diffractive system X proton:p 2 ’ proton:p 1 ’ rapidity gap  min  max  2 = – ln    1 = – ln  

27. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 27 Hard Diffractive Events Diffractive events with high p T particles produced M M hard Double Pomeron Exchange hard p p jet 1 (p T 1 ) jet 2 (p T 2 ) jet 3 (p T 3 ) p gg u d u Single diffraction: pp  p + 3j Double pomeron Ex: pp  pjjXp  = 1  b p T > 10 GeV Acc = 29.3% (for  * =90 m, prel.) (V. Avati)

28. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 28 Exclusive Double Pomeron Exchange TOTEM-CMS FP420 (with ATLAS/CMS) H p p

29. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 29 Exclusive Double Pomeron Exchange Quantum numbers are defined for exclusive particle production Gluonic states  c,  b, Higgs, supersymmetric Higgs,….. M X 2 =     s Motivation from KMR calculations (e.g. hep-ph 0111078) Selection rules mean that central system is (to a good approx) 0 ++ H → b-bbar: QCD b-bbar bkgd suppressed by J z =0 selection rule If you see a new particle produced exclusively with proton tags you know its quantum numbers Tagging the protons means excellent mass resolution (~ GeV) irrespective of the decay products of the central system Proton tagging may be the discovery channel in certain regions of the MSSM Trigger studies were discussed by M. Ruspa

30. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 30 Diffractive: H  bb Yuk. coupling,  M H, 0 ++ Inclusive: H,A   wide bump m H =140 m H =160 L=60 fb -1 55 Tasevsky et al From A. Martin’s parallel session talk SUSY Higgs: h, H, A, (H +, H -- )

31. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 31 From A. Martin’s parallel session talk  (pp  p + H + p) ~ 3 fb at LHC for SM 120 GeV Higgs L(LHC)~60 fb -1 ~10 observable events after cuts + efficiency Alan’s Conclusions There is a very strong case for installing proton taggers at the LHC, far from the IP ---- it is crucial to get the missing mass  M of the Higgs as small as possible The diffractive Higgs signals beautifully complement the conventional signals. Indeed there are significant SUSY Higgs regions where the diffractive signals are advantageous ---determining  M H, Yukawa H  bb coupling, 0 ++ determin n ---searching for CP-violation in the Higgs sector Higgs needs L ~ 10 33 cm -2 s -1, i.e. a running scenario for   = 0.5 m : trigger problems in the presence of overlapping events (see M. Ruspa’s talk) install additional Roman Pots in cold LHC region (420 m) at a later stage

32. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 32 The aim of FP420 is to install high precision silicon tracking and fast timing detectors close to the beams at 420 m from ATLAS and/or CMS. (See B. Cox’s talk in the diffractive parallel session) FP420 Project FP420 turns the LHC into a glue-glue collider where you know the beam energy of the gluons to ~ 2 GeV. With nominal LHC beam optics @ 10 33-34 cm -2 s -1 : 220 m: 0.02 <  < 0.2 420 m: 0.002 <  < 0.02  1  2 s = M 2 With √s = 14TeV, M H = 120 GeV on average:   0.009  1% Hence the need for FP420

33. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 33 Forward physics: connection to cosmic rays ALICE TOTEM LHCf

34. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 34 Issues in UHE cosmic rays 29 th ICRC Pune 1. Spectrum / GZK Cutoff

35. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 35 2. Composition X max (g/cm 2 ) Energy (eV) Measurements of the very forward energy flux (including diffraction) and of the total cross section are essential for the understanding of cosmic ray events At LHC pp energy : 10 4 cosmic events km -2 year -1 > 10 7 events at the LHC in one day p Fe Issues in UHE cosmic rays (O. Adriani)

36. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 36 UHE Cosmic Rays Interpreting cosmic ray data depends on hadronic simulation programs Forward region poorly known/constrained Models differ by factor 2 or more Need forward particle/energy measurements e.g. dE/d  … Cosmic ray showers: Dynamics of the high energy particle spectrum is crucial p  Fe

37. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 37 Model Predictions: pp at the LHC Predictions in the forward region within the CMS/TOTEM acceptance

38. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 38 The dominant contribution to the energy flux is in the very forward region In this forward region the highest energy measurements of  0 cross section were done by UA7 (E=10 14 eV, y = 5÷7) Simulation of an atmospheric shower due to a 10 19 eV proton. The direct measurement of the  production cross section as function of p T is essential to correctly estimate the energy of the primary cosmic rays (LHC: 10 17 eV) Measurement of Photons and Neutral Pions in the Very Forward Region of LHC LHCf (O. Adriani)

39. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 39 INTERACTION POINT Detector II Tungsten Scintillator Silicon  strips Detector I Tungsten Scintillator Scintillating fibers Beam line 140 m Experimental Method: 2 independent detectors on both sides of IP IP1 (ATLAS) LHCf The vacuum tube contains two counter- rotating beams. The beams transition from one beam in each tube to two beams in the same tube. Detectors will be installed in the TAN region, 140 m away from the Interaction Point, in front of luminosity monitors Charged particle are swept away by magnets LHCf will cover up to y → ∞ (O. Adriani)

40. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 40 There are plans at the LHC for a wide range of Forward and Diffractive measurements that can be achieved at a variety of different luminosities: Measure total cross-section  tot with a precision of 1% Measure elastic scattering in the range 10 -3 <|t|< 8 GeV 2 A study of soft and hard diffractive physics:  semi-hard diffraction (p T > 10 GeV)  hard diffraction  Inclusive DPE Studies of Exclusive Double Pomeron Exchange events Studies of very forward particle production  Connection with UHE Cosmic ray phenomena  Special exotics (centauro’s, DCC’s in the forward region) Summary

41. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 41 Extra slides

42. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 42 Elastic Scattering:  = Re f(s,0)/Im f(s,0) TOTEM  Ref + (s,0)/Imf + (s,0) (analyticity of the scattering amplitude via dispersion relations)  constant/lns with s 

43. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 43 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 selection only possible at luminosities below 10 33 cm -2 s -1, where event pile-up is absent

44. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 44 TOTEM Experiment (symmetric about IP5) T1 & T2 RP

45. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 45 FP420 Acceptance and Resolution 3 mm 5 mm 7.5 mm 10 mm 3 mm + 3 mm 22 mm 30 mm 25 mm MB apertures

46. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 46 Planar technology: Testbeam 40  m dead area Detector 1 Detector 2 active edges (“planar/3D”) planar technology CTS (Curr. Termin. Struct.) 50  m dead area10  m dead area 66  m pitch Add here photo of RP Active edges: X-ray measurement  m Signal [a.u.] 5  m dead area Strip 1 Strip 2 Edgeless silicon detectors for the RP 10 planes/pot

47. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 47 Diffraction at  * = 1540 m Acceptance Diffractive protons are observed in a large  -t range:  =  p/p; t=-(p  ) 2  90% are detected  -t > 2.5x10 -3 GeV 2  10 -8 <  < 0.1   resolution ~5x10 -3 kinematically excluded RP at 220 m acc. < 10%

48. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 48 Diffraction at  * = 90 m Acceptance Resolution in  :  = 4x10 -4 (prel.) L<2x10 31 cm -2 s - 1

49. April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/2006 49 Diffraction at  * = 0.5 m