TOTEM Physics
 s tot
Politecnico di Bari and Sezione INFN

elastic scattering
Bari, Italy
Case Western Reserve University

diffraction (together with CMS)
Cleveland, Ohio,USA
Institut für Luft- und Kältetechnik,
Dresden, Germany
CERN, Geneva, Switzerland
Karsten Eggert
CERN, PH Department
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
TOTEM TDR is fully approved by the
LHCC and the Research Board
K.Eggert/CERN
on behalf of the
TOTEM Collaboration
http://totem.web.cern.ch/Totem/
TOTEM Physics
Total cross-section with a precision of 1%
Elastic pp scattering in the range 10 -3 < 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)
K.Eggert/CERN
K.Eggert/CERN
TOTEM Experiment
K.Eggert/CERN
Total p-p Cross-Section
• Current models predictions:
90-130 mb
• Aim of TOTEM:
~1% accuracy
COMPETE Collaboration fits all available hadronic data and predicts:
LHC:
K.Eggert/CERN
s tot  111.5  1.2  4.1 mb
 2.1
[PRL 89 201801 (2002)]
Experimental apparatus
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.5
2
Ls tot

16 dN

2
1 
dt
Optical
Theorem
t 0
Ls tot  N elastic  Ninelastic
K.Eggert/CERN
s tot
(dN / dt ) t 0
16


2
1 
N el  N inel
Elastic Scattering Cross-Section
Photon - Pomeron interference  
Multigluon (“Pomeron”) exchange  e– B |t|
 t  p2 2
104 per bin
of 10-3 GeV2
diffractive structure
pQCD
wide range of
predictions
pp 14 TeV
BSW model
1540 m
L = 1.6 x 1028 cm-2 s-1
b*=18 m
L = 3.6 x 1032 cm-2 s-1
(1)
(2)
b* =
K.Eggert/CERN
-t [GeV2]
~1 day
(1)
(2)
Elastic Scattering at low-t
Coulomb scattering
(1/L) dNel/dt = ds/dt =
[4a2(c)2G4(t)]/|t|2 + {[a(-af)stotG2(t)]/|t|}exp(-B|t|/2)
+ [stot2 (1 + 2)/16(c)2] exp(-B’|t|)
Nuclear scattering
L
dNel/dt
a
f
G(t)
K.Eggert/CERN
Coulomb-Nuclear interference
- how to calculate? (Kundrat et al.)
= integrated luminosity
= observed elastic events
= fine structure constant
= relative Coulomb-nuclear phase: = ln(0.08|t|-1 – 0.577) (see: West & Yennie, PR172(1968)1413.
= nucleon em form factor: = (1 + |t|/0.71)-2
Extrapolation uncertainty due to Coulomb interference
Extrapolation to t=0 model dependent
Error < 0.5 %
Coulomb interference
Coulomb scattering
CoulombNuclear  = Re/Im f(pp)
interference
Nuclear scattering
K.Eggert/CERN
ds/dt ~ exp( -Bt)
Change of the slope B
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
K.Eggert/CERN
Elastic Scattering- From ISR to Tevatron
~1.5 GeV2
K.Eggert/CERN
Elastic Scattering- Models (e.g. Islam et al.)
Observations:
large impact parametersdefines the region where
inelastic diffraction occurs
”Reggeon” & ”soft Pomeron”
single gluon exchange
between valence quarks
 1/t8
• 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
K.Eggert/CERN
Elastic Scattering-large t
1-gluon exchange between the three valence quarks:
each with a contribution 1/t2  1/t8!
Possible effect of a hard Pomeron
K.Eggert/CERN
Elastic Scattering- sel/stot
Rel = sel(s)/stot(s)
Rdiff = [sel(s) + sSD(s) + sDD(s)]/stot(s)
0.30
 sel  30% of stot at the LHC ?
 sSD + sDD  10% of stot (= 100-150mb) at the LHC ?
K.Eggert/CERN
0.375
Experimental apparatus
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.5
T1
K.Eggert/CERN
T2
RP1 (147 m)
CASTOR (CMS)
RP2 (180 m)
RP3 (220 m)
T1 telescope




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
K.Eggert/CERN
T2 Telescope
5.3< lhl < 6.5
Vacuum Chamber
1800 mm
400 mm
Bellow
T2
GEM Telescope: 8 planes
13500 mm from IP
K.Eggert/CERN
Castor
Calorimeter
(CMS)
T2: telescope
8 triple-GEM planes, to cope with high particle fluxes
5.3<|h|<6.6
Pads:
54(j) x 22(h) = 1536 pads
Dh x Dj = 0.06 x 0.018
~2x2 mm2 __ ~7x7 mm2
Strips:
256 (width: 80 mm,pitch: 400 mm)
Digital r/o pads
strips
pads
Technology used in COMPASS
Analog r/o circular strips
K.Eggert/CERN
GEM for the T2 Telescope
TOTEM GEM Prototype 2004
Totem GEM Final Design 2005
Full Telescope Mock up
strips
pads
K.Eggert/CERN
Prototypes of all three detectors tested in X5
test beam in 2004
K.Eggert/CERN
TRADITIONAL PLANAR DETECTOR
+ DEEP ETCHED EDGE FILLED
WITH POLYSILICON
E-field
Planar with 3D edges
p + Al
13keV 6 mm X-ray beam
n + Al
n + Al
Insensitive edge = 5 + 2 mm
Leakage current = 6 nA at 200V
K.Eggert/CERN
Edgeless Silicon Detectors for the RPs
Active edges: X-ray measurement
Signal (a.u.)
Signal [a.u.]
1.6
1.4
1.2
Add here photo of RP
1
0.8
Strip 1
5mm dead
area
0.6
0.4
Strip 2
0.2
0
0
50
100
150
200
250
300
350
400
Position (microns)
150 mm
Strip 1
Strip 2
Planar technology: Testbeam
40 mm dead area
K.Eggert/CERN
50 mm dead area
active edges
(“planar/3D”)
10 mm dead area
66 mm pitch
planar technology CTS
(Curr. Termin. Struct.)
Detector 1
Detector 2
TOTEM ROMAN POT IN CERN SPS BEAM
K.Eggert/CERN
Roman Pot
Assembly of Silicon Detectors
for the SPS test beam
Roman Pot unit (Final Design) :
Tracks
K.Eggert/CERN
0
BPM
-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
b functions at the LHC for b*=0.5 m
K.Eggert/CERN
TOTEM Optics Conditions
L
TOTEM
~ 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(*) = 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 y*+ vy y*
L = (bb*)1/2 sin m(s)
x = Lx x *+vx x*+x Dx
v = (b/b*)1/2 cos m(s)
Maximize L and minimize v
K.Eggert/CERN
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
y  Ly *y  v y y *
x  L   vx x  Dx
*
x x
K.Eggert/CERN
*
Elastic Scattering
b* = 1540 m
acceptance
K.Eggert/CERN
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
K.Eggert/CERN
Elastic Cross section (t=0)
tmax = 0.1 GeV2
Statistical error
L dt=4 1032 cm-2
Uncertainty
Beam divergence
Energy offset
Beam/ detector offset
Beam offset (100 mm)
Crossing angle
10%
0.1%
0.05%
100mm
20mm
0.2mrad
Fit error
-0.05%
-0.25%
-0.1%
-0.32/-0.41 %
-0.06/-0.08 %
-0.08/-0.1%
Energy offset (0.1%)
Theoretical uncertainty (model dependent) ~ 0.5%
Beam offset (20 mm)
K.Eggert/CERN
Accuracy of s tot
(sinel.~80mb, sel.~30mb)
Trigger Losses (mb)
s(mb)
Double
arm
Single arm
After Extrapolation
Minimum bias
58
0.3
0.06
0.06
Single diffractive
14
-
2.5
0.6
Double diffractive
7
2.8
0.3
0.1
Double Pomeron
1
-
-
0.02
Elastic Scattering
30
-
-
0.1
Ds tot
s tot
 0.0082  0.0052  0.01
Inelastic error
t=0 extrapol. error
Vertex extrapolation
simulated
Acceptance
extrapolated
detected
K.Eggert/CERN
Possibilities of  measurement
Try to reach the Coulomb region and measure interference:
• move the detectors closer to the beam than 10 s + 0.5 mm
• run at lower energy √s < 14 TeV
K.Eggert/CERN
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
T1,T2
T1,T2
Roman Pots
Roman Pots
dNch/dh
Total TOTEM/CMS acceptance
Charged
particles
b *=90m
ZDC
CMS
dE/dh
central
TOTEM+CMS
T1
HCal
T2
CASTOR
Energy
flux
b *=1540m
Pseudorapidity:
K.Eggert/CERN
RPs
h = ln tg /2
Running Scenarios
Scenario
Physics:
K.Eggert/CERN
1
low |t| elastic,
stot ,
min. bias,
soft diffraction
2
Semi-hard
diffraction
3
hard
diffraction
large |t| elastic
(under study)
b* [m]
1540
1540
90
N of bunches
43
156
936
N of part. per bunch
0.3 x 1011
1.15 x 1011
1.15 x 1011
Half crossing angle
[mrad]
0
0
100
Transv. norm. emitt.
[mm rad]
1
3.75
3.75
RMS beam size at IP
[mm]
450
880
200
RMS beam divergence
[mrad]
0.29
0.57
2.4
Peak luminosity
[cm-2 s-1]
1.6 x 1028
2 x 1029
~ 2 x 1031
Diffractive protons at b*=1540 m
log(x)
Diffractive protons are
observed in a large x-t range
> 90% are detected
-t > 2.5 10 -3 GeV2
10-8 < x < 0.1
x resolution ~ few ‰
log(-t)
K.Eggert/CERN
420
(mm)
(mm)
mm
Diffractive proton
detection
at b*  0.5 m
x > 2.5 %
(mm)
(mm)
log x
log x
log -t
K.Eggert/CERN
log -t
New optics b* 0 m
To optimize diffractive proton detection at L=1031 in the “warm” region at 220m
• Ly large (~270 m)
Lyy
Lxx+vxx*+xD
tmin = 3 x 10-2 GeV2
30mm
• Lx ~ 0
 independent
10mm (CMS)
=0
10s beam
• Vertex measured by CMS
~ 65% of all diffractive protons
are seen
K.Eggert/CERN
x determination with a precision
of few 10 -4
-2
Particle elongation (x) for Lx=0 and different x-values
Lx
x(m)
x(m)
Lx = 0
x
 Lx=0
Example at x=0.007 and
different emission angles
s(m)
K.Eggert/CERN
s(m)
X220-x216 (mm)
b*=172 m: x resolution ~ 4 10-4 (preliminary)
x= 10-3
2 10-3
2s
2s
(x220+x216)/2 (mm)
K.Eggert/CERN
Diffractive protons at b*=172 m
420
Log(x) vs Log(-t (GeV2))
K.Eggert/CERN
Log(x) vs Log(-t)
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





K.Eggert/CERN
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
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
X
-Triggered by leading proton and
seen in CMS
-Central production of states X:
X = cc, cb, Higgs, dijets,
SUSY particles, ...
K.Eggert/CERN
Diffraction
Example:
Dh1
M
Dh2
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
Unlike minimum bias events:
p
g, q
g, q
p
K.Eggert/CERN
Exchange of colour triplets or octets:
Gaps filled by colour exchange in hadronisation
 Exponential suppression of rapidity gaps:
P(Dh) = e- Dh,
 = dn/dh
Diffractive Deep Inelastic Scattering
e’
Q2
xIP = fraction of proton’s momentum
e
taken by Pomeron
g*
b
xIP
p
IP
t
d 4s
4a 2

2
dbdQ dxIP dt
bQ 4
Naively, if IP were particle:
[Ingelman, Schlein]
K.Eggert/CERN
p’
= x in Fermilab jargon
= Bjorken’s variable for the Pomeron
= fraction of Pomeron’s momentum
carried by struck quark
= x/xIP

 D ( 4)
y2
2
1

y

F
(
b
,
Q
, xIP , t )

D ( 4)  2
2(1  R
)

F2D(4)  fIP (xIP,t) F2IP (b,Q2)
Flux of Pomerons
“Pomeron structure function”
Test factorisation in pp events
hard
scattering
FDJJ ?(= F2D)
Factorisation of diffractive PDFs not expected to hold for
pp, pp scattering – indeed it does not:
jet
b
jet
LRG
IP
Normalisation discrepancy (x10)
(depends on s [CDF, D0])
Hard scattering
factorisation violated in pp
(lots more evidence available)
K.Eggert/CERN
(x =xIP)
Example Processes
Single Diffraction:
X
p1
MX2 = x s
P
p2
x
p2’
p2  p2 '
p2
ds/dh
proton:p2’
rapidity gap
Dh =–lnx
diffractive system X
hmin 0
ln(2pL/pT)
hmax
Measure leading proton ( x) and rapidity gap ( test gap survival).
Double Pomeron Exchange:
p1’
p1
P
X
p2
P
diffractive system X
proton:p2’
MX2 = x1 x2 s
p2’
rapidity gap
Dh2=– ln x2
hmin
rapidity gap
Dh1=– ln x1
hmax
Measure leading protons ( x1, x2) and compare with MX, Dh1, Dh2
K.Eggert/CERN
proton:p1’
Hard Diffractive Events
Diffractive events with high pT particles produced
hard
M
Probing the hard structure
hard
hard
Double
Pomeron
Exchange
K.Eggert/CERN
of the Pomeron
M
ET > 10 GeV
Rates at L = 2 1029 cm-2 s-1
sincl ~1 mb
sexcl ~ 7 nb
720/h
5/h
M ( j1,j2) = 120 GeV
Rates at L = 2 1031 cm-2 s-1
sexcl ~ 18 pb / DM=10 GeV
30/day
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 cc , cb , Higgs, supersymmetric Higgs,…..
Clean gluon-gluon interactions
K.Eggert/CERN
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
Rate at
1031 cm-2 s-1
(no acceptance / analysis cuts)
[KMRS]
g J/y  g m+m–
+ – K+ K–
6 x 10-4
0.018
1.5 / h
46 / h
62 / h
1900 / h
[KMRS]
g U  g m+m–
< 10-3
0.07 / d
3/d
bb
0.68
0.02 / y
1/y
cc0
(3.4 GeV)
3 mb
cb0
(9.9 GeV)
4 nb
H
(120 GeV)
0.1  100 fb
assume 3 fb
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
K.Eggert/CERN
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* :
H
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
•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
K.Eggert/CERN
See e.g. J. Forshaw HERA/LHC workshop
x and t distributions for 120 GeV Higgs (b*=90 m)
input
ExHume
Proton acceptance 68%
Detected protons
at 220 m
Uncertain predictions !
log x
log -t
log x
log -t
Phojet
Proton acceptance 63%
K.Eggert/CERN
Mass Acceptance in DPE (preliminary)
b=0.5 m
420 + 220 m
Phojet
ExHume
ExHume
b= 90 m
220 m
420 m
K.Eggert/CERN
Phojet
Detection Prospects for Double Pomeron Events
p1’
p1
P
p2
p
P
b* = 1540 m:
sx ~ 0.5%
b* =
sx ~ 4 10 -4
90 m:
b* = 0.5 m
M2 = x1 x2 s
– ln x1
L < 1033 cm-2 s-1
Trigger via rapidity gap x < 2.5 x 10-2
Dy = – ln x
p
– ln x2
ymax = 6.5
CMS + TOTEM
CMS
y
K.Eggert/CERN
L ~ 0.2 1032 cm-2 s-1
Trigger via Roman Pots x > 2.5 x 10-2
p2’
dN/dy
sx ~ 0.2-0.6 ‰
L  2.4 x 1029 cm-2 s-1
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
0
2.6 | 7e-3
371
1x10^33
3.5
26 | 4
6.5
2x10^33
7
52 | 14.5
3.6
Effect of adding the ‘loosest’ RP condition in
either 220m pot, on the total QCD dijet rate.
5x10^33
17.6
130 | 73
1.8
Reduction in rate of around 370 at 40GeV.
Roman Pot trigger
Caveat: 75 nsec bunch spacing at the LHC start
K.Eggert/CERN
Mass resolution at 420 m and 420+220m
Note:
beam position accuracy
10 mm
420m PHOJET
Asym. 420+215 m
420m EXHUME
K.Eggert/CERN
MSSM Higgs is the hope
Examples:
1. mA = 130 GeV
tan b = 30
tan b = 50
mA
s x BR (A bb)
130 GeV
0.07 fb
130 GeV
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
tan b = 30
tan b = 50
mA
s x BR (A bb)
100 GeV
0.4 fb
100 GeV
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
2. mA = 100 GeV
[from A. Martin]
Comparison:
SM with mH = 120 GeV:
s x BR (H bb) = 2 fb
K.Eggert/CERN
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 < h < 6.7
4 pt2
x1 x2 
s
Proton structure at low-x:
Parton saturation effects?
as
Q
2
(
)
x g x, Q 2   R 2
Saturation or growing
proton?
K.Eggert/CERN
K.Eggert/CERN
Colour Transparency
Parton localisation?
pT plane:
Single diffraction: pp  p + 3j
u
p
g
g
d
u
p
Estimated cross-section
jet 1 (pT 1)
jet 2 (pT 2)
jet 3 (pT 3)
p
10 GeV
j1
j2
10 GeV
K.Eggert/CERN
10 GeV
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
8
s3 jets
j3
 5 GeV 
 (10  100) nb , where one of the jets has p > p

T
T min
 pT min 


1 day at L = 2 x 1031 cm-2 s-1 with pT min = 10 GeV:
80  800 events
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
K.Eggert/CERN
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/dh…
K.Eggert/CERN
Model Predictions: proton-proton at the LHC
Predictions in the forward region within the CMS/TOTEM acceptance
K.Eggert/CERN
Photon - photon physics
K.Eggert/CERN
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 10 -3 < 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 ~ 0.2 1032 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
K.Eggert/CERN
K.Eggert/CERN
Exclusive Central Diffraction
The Pomeron has the internal quantum numbers of vacuum.
p1’
p1
P
PP: C = +, I=0,...
P: JP = 0+, 2+, 4+,...
P
p2’  PP:
p2
JPC
=
Large mass objects O(1TeV)
0++
2
Gap
f
0
Jet+Jet
hmin
h
Signature:
2 Leading Protons &
2 Rapidity Gaps
hmax
cc: 10
6-7
events before decay
cb: 10
3-4
events before decay
- a precursor to DPE Higgs, SUSY
Gap
diffractive system
proton:p2’
rapidity gap
hmin
proton:p1’
rapidity gap
hmax
Exclusive physics  Gluon factory  Threshold scan for New Physics
K.Eggert/CERN