1. TOTEM Physics s tot TOTEM Collaboration elastic scattering
diffraction (together with CMS)
Politecnico di Bari and Sezione INFN
Bari, Italy
Case Western Reserve University
Cleveland, Ohio,USA
Institut für Luft- und Kältetechnik, Dresden, Germany
CERN, Geneva, Switzerland
Università di Genova and Sezione INFN Genova, Italy
University of Helsinki and HIP,
Helsinki, Finland
Academy of Sciences,
Praha, Czech Republic
Penn State University
University Park, USA
Brunel University, Uxbridge, UK
Karsten Eggert
CERN, PH Department
on behalf of the
TOTEM Collaboration
TOTEM TDR is fully approved by the LHCC and the Research Board

2. TOTEM Physics Total cross-section with a precision of 1%
Elastic pp scattering in the range < t = (p  )2 < 10 GeV2
Particle and energy flow in the forward direction
Measurement of leading particles
Diffractive phenomena with high cross-sections
Different running scenarios (b* = 1540, 170, 18, 0.5 m)

4. TOTEM Experiment

5. Total p-p Cross-Section
Current models predictions: mb
Aim of TOTEM: ~1% accuracy
COMPETE Collaboration fits all available hadronic data and predicts:
LHC:
[PRL (2002)]

6. Experimental apparatus
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.5
Optical Theorem

7. Elastic Scattering Cross-Section
Photon - Pomeron interference  r
Multigluon (“Pomeron”) exchange  e– B |t|
104 per bin
of 10-3 GeV2
ds/dt [mb / GeV2]
 t  p2 q2
diffractive structure
pQCD
wide range of
predictions
pp 14 TeV
BSW model
-t [GeV2]
b* = 1540 m
L = 1.6 x 1028 cm-2 s-1
(1)
b*=18 m
L = 3.6 x 1032 cm-2 s-1
(2)
~1 day
(1) (2)

8. Elastic Scattering at low-t
Coulomb scattering
(1/L) dNel/dt = ds/dt =
[4pa2(c)2G4(t)]/|t|2 + {[a(r-af)stotG2(t)]/|t|}exp(-B|t|/2)
+ [stot2 (1 + r2)/16p(c)2] exp(-B’|t|)
Nuclear scattering
Coulomb-Nuclear interference
- how to calculate? (Kundrat et al.)
L = integrated luminosity
dNel/dt = observed elastic events
a = fine structure constant
= relative Coulomb-nuclear phase: = ln(0.08|t|-1 – 0.577) (see: West & Yennie, PR172(1968)1413.
G(t) = nucleon em form factor: = (1 + |t|/0.71)-2

9. Extrapolation uncertainty due to Coulomb interference
Extrapolation to t=0 model dependent
Error < 0.5 %
ds/dt ~ exp( -Bt)
Coulomb interference
Coulomb scattering
Nuclear scattering
Coulomb-
Nuclear
interference
Change of the slope B
r = Re/Im f(pp)

10. 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

11. Elastic Scattering- From ISR to Tevatron
~1.5 GeV2

12. Elastic Scattering- Models (e.g. Islam et al.)
large impact parameters-
defines the region where
inelastic diffraction occurs
”Reggeon” & ”soft Pomeron”
single gluon exchange
between valence quarks
 1/t8
Observations:
fwd diffraction cross section increases,
diffractive peak shrinks
interference dip moves to smaller t
at –t  1 GeV2
ds/dt  1/t8 , little s dependence
(Donnachie & Landshoff)
 1/t8

13. Elastic Scattering-large t
Possible effect of a hard Pomeron
Elastic Scattering-large t
1-gluon exchange between the three valence quarks:
each with a contribution 1/t2  1/t8!

14. Elastic Scattering- el/tot
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 (= mb) at the LHC ?

15. Experimental apparatus
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.5 T1 T2
CASTOR (CMS)
RP1 (147 m)
RP2 (180 m)
RP3 (220 m)

16. T1 telescope Support 1 arm
5 planes with measurement of three coordinates per plane.
3 degrees rotation and overlap between adjacent planes
Primary vertex reconstruction
Trigger with CSC wires
1 arm
Support

17. Castor Calorimeter(CMS) GEM Telescope: 8 planes 13500 mm from IP
T2 Telescope
5.3< lhl < 6.5
Vacuum Chamber
1800 mm
400 mm
Bellow
Castor Calorimeter(CMS) T2
GEM Telescope: 8 planes mm from IP

18. T2: telescope 8 triple-GEM planes, to cope with high particle fluxes
5.3<||<6.6
54(j) x 22(h) = 1536 pads
Pads: Dh x Dj = 0.06 x 0.018p
~2x2 mm2 __ ~7x7 mm2
Strips: (width: 80 mm,pitch: 400 mm)
Digital r/o pads
Technology used in COMPASS
pads
strips
Analog r/o circular strips

19. GEM for the T2 Telescope Totem GEM Final Design 2005
TOTEM GEM Prototype 2004
Full Telescope Mock up
pads
strips

20. Prototypes of all three detectors tested in X5 test beam in 2004
CSC RP
GEM

21. Planar with 3D edges TRADITIONAL PLANAR DETECTOR
+ DEEP ETCHED EDGE FILLED
WITH POLYSILICON
p + Al
E-field
13keV 6 mm X-ray beam
Insensitive edge = mm
Leakage current = 6 nA at 200V
n + Al
n + Al

22. Edgeless Silicon Detectors for the RPs
Add here photo of RP
Active edges: X-ray measurement
150 mm
Signal [a.u.]
5mm dead area
Strip 1
Strip 2
Planar technology: Testbeam
40 m dead area
66 mm pitch
Detector 1
Detector 2
10 mm dead area
50 mm dead area
active edges
(“planar/3D”)
planar technology CTS
(Curr. Termin. Struct.)

23. TOTEM ROMAN POT IN CERN SPS BEAM

24. Roman Pot Assembly of Silicon Detectors for the SPS test beam BPM
reconstructed track
Tracks
Roman Pot unit (Final Design) :
-Vertical and horizontal pots mounted as close as possible
-BPM fixed to the structure gives precise position of the beam
-Final prototype at the end of 2005
BPM

25.  functions at the LHC for *=0.5 m

26. TOTEM Optics Conditions
LTOTEM ~ 1028 cm-2 s –1
TOTEM needs special/independent short runs at high-b* (1540m) and low e
Scattering angles of a few mrad
High-b optics for precise measurement of the scattering angle s(q*) = e / b* ~ 0.3 mrad
As a consequence large beam size s* =  e b* ~ 0.4 mm
Reduced number of bunches ( 43 and 156 ) to avoid interactions further downstream
Parallel-to-point focusing ( v=0) :
Trajectories of proton scattered at the same angle but at different vertex locations
y = Ly qy*+ vy y* L = (bb*)1/2 sin m(s)
x = Lx qx *+vx x*+x Dx v = (b/b*)1/2 cos m(s)
Maximize L and minimize v

27. L (m) v High b optics ( 1540 m ): lattice functions
v= (b/b*)1/2 cos m(s)
L = (bb*)1/2 sin m(s)
L (m)
Parallel to point focusing in both projections v

28. Elastic Scattering
b* = 1540 m
acceptance

29. Elastic Scattering: Resolution
t-resolution (2-arm measurement)
f-resolution (1-arm measurement)
Test collinearity of particles in the 2 arms
 Background reduction.
f correlation in DPE

30. Elastic Cross section (t=0)
Beam offset (20 mm)
Energy offset (0.1%)
Beam offset (100 mm)
Statistical error
L dt= cm-2
tmax = 0.1 GeV2
Uncertainty Fit error
Beam divergence % %
Energy offset % %
0.05% %
Beam/ detector offset mm /-0.41 %
20mm /-0.08 %
Crossing angle mrad /-0.1%
Theoretical uncertainty (model dependent) ~ 0.5%

31. 1% Accuracy of s tot Trigger Losses (mb) (sinel.~80mb, sel.~30mb)
Double arm
Single arm
After Extrapolation
Minimum bias 58
0.3
0.06
Single diffractive 14 -
2.5
0.6
Double diffractive 7
2.8
0.1
Double Pomeron 1
0.02
Elastic Scattering 30
Inelastic error
t=0 extrapol. error
Vertex extrapolation
simulated
extrapolated
Acceptance
detected

32. Possibilities of r measurement
Try to reach the Coulomb region and measure interference:
move the detectors closer to the beam than 10  mm
run at lower energy √s < 14 TeV

33. CMS + TOTEM: Acceptance
largest acceptance detector ever built at a hadron collider
90% (65%) of all diffractive protons are detected for b* = 1540 (90) m
Total TOTEM/CMS acceptance
CMS
central T1
HCal T2
CASTOR
b*=90m
RPs
b*=1540m
ZDC
Roman Pots
TOTEM+CMS
T1,T2
Charged particles
dNch/dh
dE/dh
Energy
flux
Pseudorapidity:  = ln tg /2

34. min. bias, soft diffraction Semi-hard diffraction
Running Scenarios
Scenario
Physics: 1
low |t| elastic,
stot ,
min. bias, soft diffraction 2
Semi-hard diffraction 3
hard diffraction
large |t| elastic
(under study)
b* [m]
1540 90
N of bunches 43
156
936
N of part. per bunch
0.3 x 1011
1.15 x 1011
Half crossing angle
[mrad]
100
Transv. norm. emitt.
[mm rad]
3.75
RMS beam size at IP
[mm]
450
880
200
RMS beam divergence
0.29
0.57
2.4
Peak luminosity
[cm-2 s-1]
1.6 x 1028
2 x 1029
~ 2 x 1031

35. TOTEM Diffractive protons at *=1540 m Diffractive protons are
log()
log(-t)
Diffractive protons are
observed in a large -t range
> 90% are detected
-t > GeV2
10-8 <  < 0.1
 resolution ~ few ‰

36. Diffractive proton detection at b* = 0.5 m > 2.5 % (mm) (mm) mm
420
(mm)
(mm) mm
Diffractive proton
detection
at b* = 0.5 m
> 2.5 %
(mm)
(mm)
log 
log 
log -t
log -t

37. New optics b*= m Ly large (~270 m)
To optimize diffractive proton detection at L=1031 in the “warm” region at 220m
Lyy
Lxx+vxx*+D =0 -2
10m (CMS)
30mm
Ly large (~270 m)
tmin = 3 x 10-2 GeV2
Lx ~ 0
q independent
10 beam
Vertex measured by CMS
~ 65% of all diffractive protons
are seen
x determination with a precision
of few 10 -4

38. Particle elongation (x) for Lx=0 and different x-values
x(m)
s(m) 
 Lx=0
Example at x= and
different emission angles

39. TOTEM Preliminary =172 m:  resolution ~ 4 10-4 (preliminary)
= 10-3
2 10-3
X220-x216 (mm) 2 2
TOTEM
Preliminary
(x220+x216)/2 (mm)

40. TOTEM Preliminary TOTEM Preliminary Diffractive protons at b*=172 m
420
Log(x) vs Log(-t (GeV2))
TOTEM Preliminary
Log(x) vs Log(-t)
TOTEM
Preliminary

41. CMS/TOTEM Physics
CMS / TOTEM detector ideal for study of diffractive and forward physics:
almost complete rapidity coverage combined with excellent proton measurement
Hard diffractive structure in Single and Double Pomeron Exchange
Production of jets, W, J/y, heavy flavours, hard photons
Double Pomeron exchange as a gluon factory
Production of low mass systems (SUSY, c ,D-Y,jet-jet, …)
Glue balls, …
Higgs production ??? (Susy Higgs)
Low - x dynamics
Proton structure and multi-parton scattering
Color transparency
Parton saturation
Forward physics
particle and energy flow (relevant for cosmic ray interpretation)
New forward phenomena: Centauros, DCC,
gg physics

42. TOTEM+CMS Physics: Diffractive Events
Measure > 90% of leading protons with RPs
and diffractive system ‘X’ with T1, T2 and CMS. X
Double
Pomeron
Exchange
-Triggered by leading proton and
seen in CMS
-Central production of states X:
X = cc, cb, Higgs, dijets, SUSY particles, ...

43. Diffraction M clean case to study gluon-gluon interactions Dh1
Example:
Exchange of colour singlets (“Pomerons”)
 rapidity gaps Dh
Most cases: leading proton(s) with momentum loss Dp / p  x
clean case to study gluon-gluon interactions
gluon - gluon collider
Dh1 M
Dh2
Unlike minimum bias events: p
Exchange of colour triplets or octets:
Gaps filled by colour exchange in hadronisation
 Exponential suppression of rapidity gaps:
g, q
g, q p
P(Dh) = e-r Dh, r = dn/dh

44. Diffractive Deep Inelastic Scattering “Pomeron structure function”Q2 e
xIP = fraction of proton’s momentum
taken by Pomeron
= x in Fermilab jargon
b = Bjorken’s variable for the Pomeron
= fraction of Pomeron’s momentum
carried by struck quark
= x/xIP g*
xIP IP p p’ t
F2D(4)  fIP (xIP,t) F2IP (b,Q2)
Naively, if IP were particle:
[Ingelman, Schlein]
Flux of Pomerons
“Pomeron structure function”

45. Test factorisation in pp events
Factorisation of diffractive PDFs not expected to hold for pp, pp scattering – indeed it does not:
jet b
Normalisation discrepancy (x10)
(depends on s [CDF, D0])
Hard scattering
factorisation violated in pp
(lots more evidence available)
FDJJ (= F2D) ?
(x =xIP)
hard
scattering
LRG IP

46. Double Pomeron Exchange:
Example Processes
Single Diffraction: X p1
ds/dh
proton:p2’
MX2 = x s
diffractive system X
rapidity gap P
Dh =–ln
p2’
hmin
hmax p2
ln(2pL/pT)
Measure leading proton ( x) and rapidity gap ( test gap survival).
Double Pomeron Exchange: p1 p2
p2’
p1’ P
diffractive system X
proton:p2’
proton:p1’
rapidity gap
hmin
hmax X
MX2 = x1 x2 s P
Dh2=– ln x2
Dh1=– ln x1
Measure leading protons ( x1, x2) and compare with MX, Dh1, Dh2

47. Hard Diffractive Events
Diffractive events with high pT particles produced M
hard
Double
Pomeron
Exchange
Probing the hard structure
of the Pomeron
ET > 10 GeV Rates at L = cm-2 s-1
sincl ~1 mb /h
sexcl ~ 7 nb /h
M ( j1,j2) = 120 GeV Rates at L = cm-2 s-1
sexcl ~ 18 pb / M=10 GeV /day

48. Particle production in Double Pomeron Exchange Use the LHC as a clean gluon-gluon collider
Quantum numbers are defined for exclusive particle production
Gluonic states c , b , Higgs, supersymmetric Higgs,…..
Clean gluon-gluon interactions

49. Exclusive Production by DPE: Examples
Advantage: Selection rules: JP = 0+, 2+, 4+; C = +1
 reduced background, determination of quantum numbers.
Good f resolution in TOTEM: determine parity: P = (-1)J+1  ds/df ~ 1 +– cos 2f
Particle
sexcl
Decay channel BR
Rate at
2x1029 cm-2 s-1
1031 cm-2 s-1
(no acceptance / analysis cuts)
c0
(3.4 GeV)
3 mb [KMRS]
g J/y  g m+m–
p+ p– K+ K–
6 x 10-4
0.018
1.5 / h
46 / h
62 / h
1900 / h
b0
(9.9 GeV)
4 nb [KMRS]
g U  g m+m–
< 10-3
0.07 / d
3 / d H
(120 GeV)
0.1  100 fb
assume 3 fb bb
0.68
0.02 / y
1 / y
Higgs needs L ~ 1033 cm-2 s-1, i.e. a running scenario for b* = 0.5 m:
trigger problems in the presence of overlapping events
install additional Roman Pots in cold LHC region at a later stage

50. Exclusive Higgs production
Standard Model Higgs
b jets : MH = 120 GeV s = 2 fb (uncertainty factor ~ 2.5)
MH = 140 GeV s = 0.7 fb
MH = 120 GeV : 11 signal / O(10) background in 30 fb-1 for m=3 GeV
WW* : MH = 120 GeV s = 0.4 fb
MH = 140 GeV s = 1 fb
MH = 140 GeV : 8 signal / O(3) background in 30 fb-1 H
The b jet channel is possible, with a good understanding of detectors and clever level 1 trigger (need trigger from the central detector at Level-1)
The WW* (ZZ*) channel is extremely promising : no trigger problems, better mass resolution at higher masses (even in leptonic / semi-leptonic channel)
If we see SM Higgs + tags - the quantum numbers are 0++
Phenomenology moving on fast
See e.g. J. Forshaw HERA/LHC workshop

51.  and t distributions for 120 GeV Higgs (=90 m)
input
ExHume
Proton acceptance 68%
Detected protons
at 220 m
Uncertain predictions !
log 
log -t
Phojet
Proton acceptance 63%
log 
log -t

52. Preliminary Totem Mass Acceptance in DPE (preliminary) 220 m 420 m
ExHume
Phojet
=0.5 m
ExHume
Phojet
Preliminary
Totem
= 90 m

53. Detection Prospects for Double Pomeron Events
b* = 1540 m:  ~ 0.5% L  2.4 x 1029 cm-2 s-1
b* = m:  ~ L ~ cm-2 s-1
b* = m  ~ ‰ L < 1033 cm-2 s-1
p1’ p1 P
M2 = x1 x2 s
Trigger via Roman Pots x > 2.5 x 10-2
Trigger via rapidity gap x < 2.5 x 10-2 P p2
p2’
Dy = – ln x
ymax = 6.5
b* = 0.5 m
dN/dy
– ln x2
– ln x1 y p
CMS
CMS + TOTEM

54. Rate (kHz) at L= 10 32
Integrated QCD rate for events with at least two jets
Integrated QCD rate for events with at least two jets and which satisfy the ‘loose’ RP condition
R. Croft
Luminosity
Events / bx
25 nsec
Rate at 40GeV (kHz)
Reduction at 40 GeV
1x10^32
2.6 | 7e-3
371
1x10^33
3.5
26 | 4
6.5
2x10^33 7
52 | 14.5
3.6
5x10^33
17.6
130 | 73
1.8
Roman Pot trigger
Effect of adding the ‘loosest’ RP condition in either 220m pot, on the total QCD dijet rate.
Reduction in rate of around 370 at 40GeV.
Caveat: 75 nsec bunch spacing at the LHC start

55. Mass resolution at 420 m and 420+220m
Note:
beam position accuracy
10 m
420m PHOJET
Asym m
420m EXHUME

56. MSSM Higgs is the hope Examples: 1. mA = 130 GeV 2. mA = 100 GeV
tan b = 30
tan b = 50 mA
s x BR (A bb)
130 GeV
0.07 fb
0.2 fb mh
s x BR (h bb)
122.7 GeV
5.6 fb
124.4 GeV
13 fb mH
s x BR (H bb)
134.2 GeV
8.7 fb
133.5 GeV
23 fb
2. mA = 100 GeV
tan b = 30
tan b = 50 mA
s x BR (A bb)
100 GeV
0.4 fb
1.1 fb mh
s x BR (h bb)
98 GeV
70 fb
99 GeV
200 fb mH
s x BR (H bb)
133 GeV
8 fb
131 GeV
15 fb
[from A. Martin]
Comparison:
SM with mH = 120 GeV:
s x BR (H bb) = 2 fb

57. Proton structure at low x
For rapidities above 5 and masses below 10 GeV
 x down to 10-6 ÷ 10-7
Possible with T2 in TOTEM (calorimeter, tracker):
5 <  < 6.7
Proton structure at low-x:
Parton saturation effects?
Saturation or growing proton?

59. Colour Transparency Parton localisation?
pT plane:
Single diffraction: pp  p + 3j
10 GeV j1 j2 j3 p
jet 1 (pT 1)
jet 2 (pT 2)
jet 3 (pT 3) g u d
Example: 3 jets at 10 GeV
polar jet angle ~ 4.3 mrad  h ~ 6.1
jet separation ~ 7 mrad  10 cm in T2
jet width ~ 0.3  3 mrad  0.4  4 cm in T2
Estimated cross-section
, where one of the jets has pT > pT min
1 day at L = 2 x 1031 cm-2 s-1 with pT min = 10 GeV:  800 events

60. Integral flux of high energy cosmic rays
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:
104 cosmic events km-2 year-1
> 107 events at the LHC in one day

61. High Energy Cosmic Rays
Cosmic ray showers:
Dynamics of the
high energy particle
spectrum is crucial
Interpreting cosmic ray data depends
on hadronic simulation programs
Forward region poorly know/constrained
Models differ by factor 2 or more
Need forward particle/energy measurements
e.g. dE/d…

62. Model Predictions: proton-proton at the LHC
Predictions in the forward region within the CMS/TOTEM acceptance

63. Photon - photon physics

64. Conclusions Measure total cross-section stot with a precision of 1 %
L = ~1028 cm-2 s-1 with b* = 1540 m
Measure elastic scattering in the range < t < 8 GeV 2
With the same data study of soft diffraction and forward physics:
~ 107 single diffractive events
~ 106 double Pomeron events
With b* = 1540 m optics at L = 2  1029 cm-2 s-1 :
semi-hard diffraction (pT > 10 GeV)
With b* = 90 m optics (under study) at L ~ cm-2 s-1:
hard diffraction and DPE
Study of rare events (Higgs, Supersymmetry,…) with b* = 0.5 m
using eventually detectors in the cold region (420m) 
Detailed study of the structure of the proton and the parton interactions

66. Exclusive Central Diffraction
The Pomeron has the internal quantum numbers of vacuum.
Signature:
2 Leading Protons &
2 Rapidity Gaps
p1’ p1
PP: C = +, I=0,...
P: JP = 0+, 2+, 4+,...
PP: JPC = 0++ P P
Large mass objects O(1TeV)
c: events before decay
b: events before decay
- a precursor to DPE Higgs, SUSY
p2’ p2 2p 
Gap
Jet+Jet
Gap
diffractive system
proton:p1’
hmin h
hmax
proton:p2’
rapidity gap
rapidity gap
hmin
hmax
Exclusive physics  Gluon factory  Threshold scan for New Physics