K.Eggert/CERN
TOTEM PhysicsTOTEM Physics tot
elastic scattering diffraction (together with
CMS) Karsten Eggert
CERN, PH Department
on behalf of the
TOTEM Collaborationhttp://totem.web.cern.ch/Totem/
Politecnico di Bari and Sezione INFNBari, ItalyCase Western Reserve UniversityCleveland, 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 UniversityUniversity Park, USA
Brunel University, Uxbridge, UK
TOTEM TDR is fully approved by the LHCC and the Research Board
K.Eggert/CERN
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 (* = 1540, 170, 18, 0.5 m)
K.Eggert/CERN
K.Eggert/CERN
TOTEM Experiment
K.Eggert/CERN
• Current models predictions: 90-130 mb
• Aim of TOTEM: ~1% accuracy
Total p-p Cross-SectionTotal p-p Cross-Section
mb 1.41.2 2.1 5.111 +
−±=totLHC:
COMPETE Collaboration fits all available hadronic data and predicts:
[PRL 89 201801 (2002)]
K.Eggert/CERN
02
2
116L
=
×+
=t
tot dtdN
ρπ
inelasticelastictot NN +=L inelel
ttot NN
dtdN+
×+
= =02
)/(
116ρπ
Optical Theorem
T1:3.1 << 4.7
T2: 5.3 < < 6.5
Experimental apparatus
K.Eggert/CERN
Elastic Scattering Cross-SectionElastic Scattering Cross-Section
diffractive structure
Photon - Pomeron interference ρ
pQCD
* = 1540 mL = 1.6 x 1028 cm-2 s-
1
(1)
*=18 mL = 3.6 x 1032 cm-2 s-1
(2)
pp 14 TeVBSW model
Multigluon (“Pomeron”) exchange e– B |t|
-t [GeV2]
t p2 2
d/d
t [m
b / G
eV2 ]
~1 day(1) (2)
wide range of predictions
104 per binof 10-3 GeV2
K.Eggert/CERN
Elastic Scattering at low-t
(1/L) dNel/dt = d/dt =
[4π2(c)2G4(t)]/|t|2 + {[(ρ-)totG2(t)]/|t|}exp(-B|t|/2)
+ [tot2 (1 + ρ2)/16π(c)2] exp(-B’|t|)
Coulomb scattering
Coulomb-Nuclear interference - how to calculate? (Kundrat et al.)
Nuclear scattering
L = integrated luminositydNel/dt = observed elastic events = 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
K.Eggert/CERN
Extrapolation uncertainty due to Coulomb interference
Change of the slope B
Extrapolation to t=0 model dependent
Error < 0.5 % d/dt ~ exp( -Bt)
Coulomb interference
Coulomb scattering
Nuclear scattering
Coulomb-Nuclear
interferenceρ = Re/Im f(pp)
K.Eggert/CERN
Elastic Scattering: ρ = Re f(s,0)/Im f(s,0)
TOTEM
ρ Ref+(s,0)/Imf+
(s,0)
(analyticity of thescattering amplitude via dispersion relations)
constant/lns with s
K.Eggert/CERN
Elastic Scattering- From ISR to TevatronElastic Scattering- From ISR to Tevatron
~1.5 GeV2
K.Eggert/CERN
Elastic Scattering- Models (e.g. Islam et al.)
Observations:
• fwd diffraction cross section increases, diffractive peak shrinks interference dip moves to smaller t
• at –t 1 GeV2
d/dt 1/t8 , little s dependence (Donnachie & Landshoff)
1/t8
large impact parameters-defines the region whereinelastic diffraction occurs”Reggeon” & ”soft Pomeron”
single gluon exchange between valence quarks 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- el/tot
0.375
Rel = el(s)/tot(s) Rdiff = [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 ?
K.Eggert/CERN
T1:3.1 << 4.7
T2: 5.3 < < 6.5
T1 T2 CASTOR (CMS)
RP1 (147 m) RP2 (180 m) RP3 (220 m)
Experimental apparatus
K.Eggert/CERN
T1 telescopeT1 telescope 5 planes with measurement of three 5 planes with measurement of three
coordinates per plane.coordinates per plane. 3 degrees rotation and overlap 3 degrees rotation and overlap
between adjacent planesbetween adjacent planes Primary vertex reconstructionPrimary vertex reconstruction Trigger with CSC wiresTrigger with CSC wires
Support1 arm
K.Eggert/CERN
T2GEM Telescope: 8 planes
13500 mm from IP
Castor Calorimeter
(CMS)
Vacuum Chamber
1800 mm
400 mm
Bellow
T2 Telescope5.3< ll < 6.5
K.Eggert/CERN
T2: telescopeT2: telescope
54() x 22()= 1536 padsPads: x = 0.06 x 0.018π ~2x2 mm2 __ ~7x7 mm2
Strips: 256 (width: 80 m,pitch: 400 m)
Analog r/o circular strips
Digital r/o pads
8 triple-GEM planes, to cope with high particle fluxes5.3<||<6.6
Technology used in COMPASS
pads
strips
K.Eggert/CERN
GEM for the T2 TelescopeGEM for the T2 Telescope
pads
strips
Totem GEM Final Design 2005TOTEM GEM Prototype 2004
Full Telescope Mock up
K.Eggert/CERN
Prototypes of all three detectors Prototypes of all three detectors tested in X5 test beam in 2004tested in X5 test beam in 2004
K.Eggert/CERN
Planar with 3D edgesPlanar with 3D edges
13keV 6 mm X-ray beam
Insensitive edge = 5 + 2 m
Leakage current = 6 nA at 200V
TRADITIONAL PLANAR DETECTOR + DEEP ETCHED EDGE FILLED WITH POLYSILICON
E-fieldp + Al
n + Aln + Al
K.Eggert/CERN
Planar technology: Testbeam 40 m dead area
Detector 1Detector 1 Detector 2Detector 2
Edgeless Silicon Detectors for the RPsEdgeless Silicon Detectors for the RPs
active edges(“planar/3D”)
planar technology CTS(Curr. Termin. Struct.)
50
m d
ead
area
10
m d
ead
area
66 m pitch
Add here photo of RP
Active edges: X-ray measurement
10m
Sign
al [a
.u.]
5m deadarea
Strip 1 Strip 2
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TOTEM ROMAN POT IN CERN SPS BEAM
K.Eggert/CERN
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
BPMBPM
Roman PotRoman Pot
0reconstructed track
Tracks
Assembly of Silicon Detectorsfor the SPS test beam
K.Eggert/CERN
functions at the LHC for *=0.5 m
K.Eggert/CERN
TOTEM Optics ConditionsTOTEM Optics Conditions
High- optics for precise measurement of the scattering angle (*) = / * ~ 0.3 rad
As a consequence large beam size * = * ~ 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
LTOTEM ~ 1028 cm-2 s –1
TOTEM needs special/independent short runs at high-**((1540m1540m))and and lowlowScattering angles of a few rad
y = Ly y*+ vy y* L = ()1/2 sin (s)
x = Lx x *+vx x*+Dx v = (/)1/2 cos (s)Maximize L and minimize v
K.Eggert/CERN
v= (/)1/2 cos (s)
L = ()1/2 sin (s)
High optics ( 1540 m ): lattice functions
DxvLx
yvLy
xxx
yy y
++=
+=**
**
L (m)
v
Parallel to point focusing in both projections
K.Eggert/CERN
Elastic Scattering* = 1540 m
acceptance
K.Eggert/CERN
Elastic Scattering: ResolutionElastic Scattering: Resolutiont-resolution (2-arm measurement) -resolution (1-arm measurement)
Test collinearity of particles in the 2 arms Background reduction.
correlation in DPE
K.Eggert/CERN
Elastic Cross section (t=0)
Uncertainty Fit error
Beam divergence 10% -0.05%Energy offset 0.1% -0.25% 0.05% -0.1%Beam/ detector offset 100m -0.32/-0.41 % 20m -0.06/-0.08 %Crossing angle 0.2rad -0.08/-0.1%
Theoretical uncertainty (model dependent) ~ 0.5%Beam offset (20 m)
Energy offset (0.1%)
Beam offset (100 m)
Statistical error
L dt=4 1032 cm-2
tmax = 0.1 GeV2
K.Eggert/CERN
Accuracy of tot (inel.~80mb, el.~30mb)
(mb)(mb) Double Double armarm
Single armSingle arm After ExtrapolationAfter Extrapolation
Minimum biasMinimum bias 5858 0.30.3 0.060.06 0.060.06
Single diffractiveSingle diffractive 1414 -- 2.52.5 0.60.6
Double diffractiveDouble diffractive 77 2.82.8 0.30.3 0.10.1
Double PomeronDouble Pomeron 11 -- -- 0.020.02
Elastic ScatteringElastic Scattering 3030 -- -- 0.10.1
Trigger Losses (mb)
Acceptance
Vertex extrapolation
01.0005.00.008 22 ≈+≈
tot
tot
simulated
extrapolated
detected
Inelastic error t=0 extrapol. error
K.Eggert/CERN
Try to reach the Coulomb region and measure interference:
• move the detectors closer to the beam than 10 + 0.5 mm• run at lower energy √s < 14 TeV
Possibilities of Possibilities of ρρ measurement measurement
K.Eggert/CERN
90% (65%) of all diffractive protons are detected for * = 1540 (90) m
largest acceptance detector ever built at a hadron collider
Rom
an Pots
TOTEM+CMS
T1,T2 T1,T2
Rom
an Pots
Charged particles
Energyflux
CMS + TOTEM: AcceptanceCMS + TOTEM: AcceptancedNdN
chch/d/d
dE/d
dE/d
Total TOTEM/CMS acceptance
CMScentral
T1
HCal T2 CASTOR
=90m=90m
RPs
=1540m=1540m
ZDC
Pseudorapidity: = ln tg /2
K.Eggert/CERN
Running ScenariosRunning Scenarios
ScenarioScenarioPhysics:Physics:
11low |t| elastic,low |t| elastic,
tot tot ,,min. bias, min. bias,
soft diffractionsoft diffraction
22
Semi-hard Semi-hard diffractiondiffraction
33hard hard
diffractiondiffractionlarge |t| elasticlarge |t| elastic(under study)(under study)
** [m] [m] 15401540 15401540 9090
N of bunchesN of bunches 4343 156156 936936
N of part. per bunchN of part. per bunch 0.3 x 100.3 x 101111 1.15 x 101.15 x 101111 1.15 x 101.15 x 101111
Half crossing angleHalf crossing angle[[rad]rad]
00 00 100100
Transv. norm. emitt. Transv. norm. emitt. [[m rad]m rad]
11 3.753.75 3.753.75
RMS beam size at IP RMS beam size at IP [[m]m]
450450 880880 200200
RMS beam divergence RMS beam divergence [[rad]rad]
0.290.29 0.570.57 2.42.4
Peak luminosityPeak luminosity[cm[cm-2-2 s s-1-1]]
1.6 x 101.6 x 102828 2 x 102 x 102929 ~ 2 x 10~ 2 x 103131
K.Eggert/CERN
TOTEM
log()
log(-t)
Diffractive protons are observed in a large -t range> 90% are detected
-t > 2.5 10 -3 GeV2
10-8 < < 0.1
resolution ~ few ‰
Diffractive protons at *=1540 m
K.Eggert/CERN
Diffractive proton detection at =0.5 m> 2.5 %
mm
log
log -t
420
(mm)
(mm)(mm)
(mm)
log -t
log
K.Eggert/CERN
New optics =0m
• Ly large (~270 m) tmin = 3 x 10-2 GeV2
• Lx ~ 0 independent
• Vertex measured by CMS
determination with a precision of few 10 -4
To optimize diffractive proton detection at L=1031 in the “warm” region at 220m
Lyy Lxx+vxx*+D
=0 -210m (CMS)
30mm
~ 65% of all diffractive protons are seen
10 beam
K.Eggert/CERN
Particle elongation (x) for Lx=0 and different -values
Lx = 0
x(m)x(m)
s(m) s(m)
Example at =0.007 and different emission angles
Lx=0
Lx
K.Eggert/CERN
X22
0-x 2
16 (
m)
(x220+x216)/2 (mm)
2
2
=172 m: resolution ~ 4 10-4 (preliminary)
TOTEM
Prelim
inary
= 10-3 2 10-3
K.Eggert/CERN
Diffractive protons at =172 m
Log() vs Log(-t (GeV2))
TOTEM
Prel
iminar
y
Log() vs Log(-t)
TOTEM
Prelim
inary
420
K.Eggert/CERN
CMS/TOTEM PhysicsCMS/TOTEM Physics
CMS / TOTEM detector ideal for study of diffractive and forward physics:CMS / TOTEM detector ideal for study of diffractive and forward physics:
almost complete rapidity coverage combined with excellent proton measurementalmost complete rapidity coverage combined with excellent proton measurement
Hard diffractive structure in Single and Double Pomeron ExchangeHard diffractive structure in Single and Double Pomeron Exchange
Production of jets, W, J/, heavy flavours, hard photons
Double Pomeron exchange as a gluon factoryDouble Pomeron exchange as a gluon factory
Production of low mass systems (SUSY, ,D-Y,jet-jet, …) Glue balls, … Higgs production ??? (Susy Higgs)
Low - x dynamicsLow - x dynamics
Proton structure and multi-parton scattering
Color transparency
Parton saturation
Forward physicsForward physics
particle and energy flow (relevant for cosmic ray interpretation)
New forward phenomena: Centauros, DCC,
physicsphysics
K.Eggert/CERN
TOTEM+CMS Physics: Diffractive EventsTOTEM+CMS Physics: Diffractive Events
X
XDoublePomeronExchange
-Triggered by leading proton and seen in CMS-Central production of states X: X = c, b, Higgs, dijets, SUSY particles, ...
Measure > 90% of leading protons with RPs and diffractive system ‘X’ with T1, T2 and CMS.
K.Eggert/CERN
DiffractionDiffraction
Exchange of colour singlets (“Pomerons”) rapidity gaps Most cases: leading proton(s) with momentum loss p / p
clean case to study gluon-gluon interactionsgluon - gluon collider
P() = e-ρ, ρ = dn/d
p
p
g, qg, q
Exchange of colour triplets or octets:Gaps filled by colour exchange in hadronisation
Exponential suppression of rapidity gaps:
Unlike minimum bias events:
Example:
1
2
M
K.Eggert/CERN
Diffractive Deep Inelastic Scattering
xIP = fraction of proton’s momentum taken by Pomeron = inFermilab jargon= Bjorken’s variable for the Pomeron = fraction of Pomeron’s momentum carried by struck quark = x/xIP
Flux of Pomerons
),,,()1(2
14 2)4(2)4(
2
4
2
2
4
txQFRyy
QdtdxdQdd
IPD
DIP
π
⎭⎬⎫
⎩⎨⎧ +
+−=
“Pomeron structure function”
F2D(4) fIP (xIP,t) F2
IP (,Q2)Naively, if IP were particle:
[Ingelman, Schlein]
xIP IP
Q2
t
*
e
e’
p p’
K.Eggert/CERN
jet
jet
hard scattering
IPLRG
Test factorisation in pp events
Normalisation discrepancy (x10)(depends on s [CDF, D0])
Hard scattering factorisation violated in pp(lots more evidence available)
FDJJ
(= F
2D)
?
(=xIP)
Factorisation of diffractive PDFs not expected to hold for pp, pp scattering – indeed it does not:
K.Eggert/CERN
Example ProcessesExample Processes
2
22 'ppp −
=
P
p1
p2p2’
X d/dproton:p2’
diffractive system Xrapidity gap =–ln
min 0ln(2pL/pT) max
Measure leading proton ( ) and rapidity gap ( test gap survival).
Single Diffraction:
2=– ln 2 1=– ln 1
p1
p2 p2’
p1’
PMX
2 = 12s
PX
diffractive system Xproton:p2’proton:p1’
rapidity gaprapidity gap
min max
Double Pomeron Exchange:
Measure leading protons ( 1, 2) and compare with MX, 1, 2
MX2 = s
K.Eggert/CERN
Hard Diffractive EventsHard Diffractive Events
Diffractive events with high pT particles produced
M
M
hard
hard
DoublePomeronExchange
hard
ET > 10 GeV Rates at L = 2 1029 cm-2 s-1
incl ~1 b 720/h
excl ~ 7 nb 5/h
M ( j1,j2) = 120 GeV Rates at L = 2 1031 cm-2 s-1
excl ~ 18 pb / M=10 GeV 30/day
Probing the hard structure
of the Pomeron
K.Eggert/CERN
Particle production in Double Pomeron ExchangeParticle production in Double Pomeron Exchange
Use the LHC as a clean gluon-gluon colliderUse 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
K.Eggert/CERN
Exclusive Production by DPE: ExamplesExclusive Production by DPE: Examples
Advantage: Selection rules: JP = 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
ParticleParticle exclexcl Decay channelDecay channel BRBR Rate at Rate at 22xx10102929 cm cm-2-2 s s-1-1
Rate at Rate at 10103131 cm cm-2-2 s s-1-1
(no acceptance / analysis cuts)(no acceptance / analysis cuts)
c0c0
(3.4 GeV)(3.4 GeV) 3 3 b b [KMRS][KMRS] J/J/ ++––
ππ+ + ππ– – KK+ + KK––
6 x 106 x 10-4-4
0.0180.0181.5 / h1.5 / h46 / h46 / h
62 / h62 / h1900 / h1900 / h
b0b0
(9.9 GeV)(9.9 GeV) 4 nb 4 nb [KMRS][KMRS] ++–– < 10< 10-3-3 0.07 / d0.07 / d 3 / d3 / d
HH(120 GeV)(120 GeV)
0.1 0.1 100 fb 100 fbassume 3 fbassume 3 fb bbbb 0.680.68 0.02 / y0.02 / y 1 / y1 / y
Higgs needs L ~ 1033 cm-2 s-1, i.e. a running scenario for = 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
H
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 dm=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
Standard Model Higgs
•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++
Exclusive Higgs productionExclusive Higgs production
Phenomenology moving on fast See e.g. J. Forshaw HERA/LHC workshop
K.Eggert/CERN
ExHume
Phojet
log -t
log -t
log
log
input
and t distributions for 120 GeV Higgs (=90 m)
Proton acceptance 68%
Proton acceptance 63%
Detected protons at 220 m
Uncertain predictions !
K.Eggert/CERN
ExHume
Phojet
Mass Acceptance in DPE (preliminary)
= 90 m
=0.5 m
220 m
420 m
420 + 220 m
ExHume
PhojetTotem
Prelim
inary
K.Eggert/CERN
y = – ln
ymax = 6.5
Trigger via Roman Pots > 2.5 x 10-2
Trigger via rapidity gap < 2.5 x 10-2
* = 1540 m: ~ 0.5% L 2.4 x 1029 cm-2 s-1
* = 90 m: ~ 4 10 -4 L ~ 0.2 1032 cm-2 s-1
* = 0.5 m ~ 0.2-0.6 ‰ L < 1033 cm-2 s-1
Detection Prospects for Double Pomeron EventsDetection Prospects for Double Pomeron Events
dN/dy
– ln 2– ln 1
y
pp
CMS
CMS + TOTEM
p1
p2 p2’
p1’
PM2 = 12s
P* = 0.5 m
K.Eggert/CERN
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
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
LuminosityLuminosity Events / bxEvents / bx25 nsec25 nsec
Rate at 40GeV Rate at 40GeV (kHz)(kHz)
Reduction at Reduction at 40 GeV40 GeV
1x10^321x10^32 00 2.6 | 7e-32.6 | 7e-3 371371
1x10^331x10^33 3.53.5 26 | 426 | 4 6.56.5
2x10^332x10^33 77 52 | 14.552 | 14.5 3.63.6
5x10^335x10^33 17.617.6 130 | 73130 | 73 1.81.8
Rate (kHz) at L= 10 32
R. Croft
Roman Pot trigger
K.Eggert/CERN
420m PHOJETAsym. 420+215 m420m EXHUME
Mass resolution at 420 m and 420+220m
Note:beam position accuracy 10 m
K.Eggert/CERN
MSSM Higgs is the hopeMSSM Higgs is the hope
tan tan = 30 = 30 tan tan = 50 = 50
mmAA
x BR (Ax BR (A bb) bb)130 GeV130 GeV0.07 fb0.07 fb
130 GeV130 GeV0.2 fb0.2 fb
mmhh
x BR (hx BR (h bb) bb)122.7 GeV122.7 GeV5.6 fb5.6 fb
124.4 GeV124.4 GeV13 fb13 fb
mmHH
x BR (Hx BR (H bb) bb)134.2 GeV134.2 GeV8.7 fb8.7 fb
133.5 GeV133.5 GeV23 fb23 fb
Examples:1. mA = 130 GeV
2. mA = 100 GeVtan tan = 30 = 30 tan tan = 50 = 50
mmAA
x BR (Ax BR (A bb) bb)100 GeV100 GeV0.4 fb0.4 fb
100 GeV100 GeV1.1 fb1.1 fb
mmhh
x BR (hx BR (h bb) bb)98 GeV98 GeV70 fb70 fb
99 GeV99 GeV200 fb200 fb
mmHH
x BR (Hx BR (H bb) bb)133 GeV133 GeV8 fb8 fb
131 GeV131 GeV15 fb15 fb
[from A. Martin]
Comparison:SM with mH = 120 GeV: x BR (H bb) = 2 fb
K.Eggert/CERN
For rapidities above 5 and masses below 10 GeV For rapidities above 5 and masses below 10 GeV x down to 10x down to 10-6 -6 ÷ ÷ 1010-7-7
Possible with T2 in TOTEM (calorimeter, tracker):Possible with T2 in TOTEM (calorimeter, tracker):5 5 < < < < 6.76.7
Proton structure at low-x:Parton saturation effects?
( ) 222 , RQxgx
Qs πα >
Saturation or growing proton?
spxx t
2
214
>
Proton structure at low x
K.Eggert/CERN
K.Eggert/CERN
Colour TransparencyColour Transparency
Parton localisation?
p
pjet 1 (pT 1)jet 2 (pT 2)jet 3 (pT 3)p
gg
u
du
Single diffraction: pp p + 3j
( )nb 10010GeV 58
3 ÷⎟⎟⎠
⎞⎜⎜⎝
⎛≈
minTjets p
σ
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: 80 800 events
Example: 3 jets at 10 GeVpolar jet angle ~ 4.3 mrad ~ 6.1jet separation ~ 7 mrad 10 cm in T2jet width ~ 0.3 3 mrad 0.4 4 cm in T2
10 GeV
10 GeV10 GeV
j1
j2 j3
pT plane:
K.Eggert/CERN
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 RaysHigh Energy Cosmic Rays
Interpreting cosmic ray data dependson hadronic simulation programsForward region poorly know/constrainedModels differ by factor 2 or moreNeed forward particle/energy measurements e.g. dE/d…
Cosmic ray showers:Dynamics of thehigh energy particle spectrum is crucial
K.Eggert/CERN
Model Predictions: proton-proton at the LHCModel 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
ConclusionsConclusionsMeasure Measure total cross-section total cross-section tot tot with a precision of with a precision of 1 % 1 % LL = ~10 = ~1028 28 cmcm-2-2 s s-1-1 with with * * = 1540 m= 1540 m
Measure Measure elastic scatteringelastic scattering in the range in the range 10 10 -3-3 < t < 8 GeV < t < 8 GeV 22
With the same dataWith the same data study of study of soft diffraction and forward physicssoft diffraction and forward physics::~ 10~ 1077 single diffractivesingle diffractive events events~ 10~ 1066 double Pomerondouble Pomeron events events
With With * * = 1540 m optics at = 1540 m optics at LL = 2 = 2 10 1029 29 cmcm-2-2 s s-1-1 : :semi-hard diffraction (psemi-hard diffraction (pTT > 10 GeV) > 10 GeV)
With With * * = 90 m optics (under study) at = 90 m optics (under study) at LL ~ 0.2 10 ~ 0.2 1032 32 cmcm-2-2 s s-1-1::hard diffraction and DPEhard diffraction and DPE
Study of rare events (Higgs, Supersymmetry,…) with Study of rare events (Higgs, Supersymmetry,…) with * = 0.5 m* = 0.5 musing eventually detectors in the cold region (420m)using eventually detectors in the cold region (420m)
Detailed study of the structure of the proton and the parton interactionsDetailed study of the structure of the proton and the parton interactions
K.Eggert/CERN
K.Eggert/CERN
Exclusive Central DiffractionThe Pomeron has the internal quantum numbers of vacuum.
PP: C = +, I=0,...
P: JP = 0+, 2+, 4+,...
PP: JPC = 0++
Gap GapJet+Jet
0
2π
p1
p2p2’
p1’
P
P
diffractive systemproton:p2’ proton:p1’
rapidity gaprapidity gap
min max
min max
Signature:2 Leading Protons &2 Rapidity Gaps
Exclusive physics Gluon factory Threshold scan for New Physics
Large mass objects O(1TeV)
c: 10 6-7 events before decay
b: 10 3-4 events before decay
- a precursor to DPE Higgs, SUSY
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