The CMS/TOTEM Forward Physics Study. Albert De Roeck (CERN) Physics with Forward Proton Taggers at the Tevatron and LHC. Introduction: CMS/TOTEM Study Physics Detectors. The Large Hadron Collider (LHC). PP collisions at s = 14 TeV 5 experiments 25 ns bunch spacing
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Albert De Roeck (CERN)
Physics with Forward Proton Taggers at the Tevatron and LHC
Introduction: CMS/TOTEM Study
23 inelastic events
per bunch crossing
In LEP tunnel
(circonf. 26.7 km)
Planned Startup: April 2007
A Hugeenterprise !
Main program: EWSB, Beyond SM physics…
-t=10-1The TOTEM Experiment
TOTEM physics program: total pp, elastic & diffractive cross sections
Apparatus: Inelastic Detectors & Roman Pots (2 stations)
High * (1540m): Lumi 1028-1030cm-2s-1(few days or weeks)
>90% of all diffractive protons are seen in the Roman Pots.
Proton momentum measured with a resolution ~10-3
Low *: (0.5m): Lumi 1033-1034cm-2s-1
215m: 0.02 < < 0.2
300/400m: 0.002 < < 0.2 (RPs in the cold region)
More on TOTEM & acceptance by R. Orava/K. Osterberg
T1/T2 inelastic event taggers
T1 CSC/RPC tracker (99 LOI)
T2 GEM or Silicon tracker (TOTEM/New)
CASTOR Calorimeter (CMS/New)
T1 3< <5
T2 5< <6.7
CASTOR 9,71 λI
Many of these studies can be done best with L ~1033 (or lower)
< 0.1 O(1) TeV “Pomeron beams“
E.g. Structure of the Pomeron F(,Q2)
down to ~ 10-3 & Q2 ~104 GeV2
Exclusive final states ?
Pt>100 GeV/c for different structure functions
H1 fit 6
H1 fit 5
H1 fit 6
H1 fit 4
=jets ET e-/(s) ; from Roman Pots; ET and from CMS
High region probed/ clear differences between different SFs
Petrov et al.
ET > 100 GeV
ET > 10 GeV
|t| dependence information on shape & size of the interaction region
Evolution in the presence of a short-time perturbation?
Exclusive diffractive Higgs production pp p H p : 3-10 fb
Inclusive diffractive Higgs production pp p+X+H+Y+p : 50-200 fb
E.g. V. Khoze et al
M. Boonekamp et al.
B. Cox et al. …
Jz=0 suppression of ggbb background
Mass measurement via missing mass
~New: Under study by
Kaidalov et al.,
Cross section factor
~ 10 larger in MSSM
between the outgoing
protons to analyse the
spin-parity structure of
the produced boson
See talk of A. Martin
Diffractive production of new heavy states pp p + M + p
Particularly if produced in gluon gluon (or ) fusion processes
Light CP violating Higgs Boson MH < 70 GeV
B. Cox et al.
Light MSSM Higgs hbb at large tan
Light H,A (M<150 GeV) in MSSM with
large tan (~ 30) S/B > 10
Medium H,A (M=150-200 GeV) medium tan ?
V. Khoze et al. (see AD Martin talk)
Radion production - couples strongly to gluons
Exclusive gluino-gluino production?
Only possible if gluino is light (< 200-250 GeV)
V. Khoze et al.
Needs Roman Pots at new positions 320 and/or 420 m
Technical challenge: “cold” region of the machine, Trigger signals…
Mass of Higgs
Detectors in this region requires changes in the machine
Signal understood (cross section)
Needs good understanding of the background (inclusive!)
Needs more complete simulations (resolutions, etc.)
Can we trigger with the central detector only for L1?
Note: L1 2-jet thresholds ET > ~150 GeV
Some Major Concerns:
Of interest for both ATLAS and CMS
No bypass option considered.
TOTEM presently not interested to follow
this up further with the machine.
Common CMS+ATLAS effort needed?
Any change now means paperwork!
LHC: due to the high energy
can reach small values of Bjorken-x
in structure of the proton F(x,Q2)
Prompt photon 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?
Rapidity ranges of jets or leptons vs x range
Dynamics of the
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
Predictions in the forward region within the CMS/TOTEM acceptance
pTwo-photon interactions at the LHC
Relative luminosity S = L/Lpp:: ~ 0.1% for W> 200 GeV
Must tag protons at small |t| with good resolution: TOTEM Roman Pots!
pTwo-photon interactions at the LHC
Sensitivity to Large
total cross section W~1000 GeV?
New studies: p interactions with 10-100x Luminosity
Number of Higgs events for single tags and assuming integrated lumi-nosity of 30, 0.3 and 0.03 fb-1 for pp, pAr and ArAr collisions, respectively.
Significant production rates and very clean signatures available - both transverse and longitudinal missing energy
Range up to 200-250 GeV
for single tags
p interactions at the LHC
Example of a QED process for luminosity monitoring
pp pp e+e-
in forward range
5< < 8
Cross section ~barns
EM calorimetry essential
Can get the luminosity to 1-2%?
So far > 5% from W,Z production
(ADR/ K. Eggert organizing)
Use synergy for e.g. simulation, physics studies & forward detector option studies.
Some of this happened e.g. RP & T2 simulation, detector options
at 150, 215 , add 310 & 420 m ? (cold section!)
T1 CSC trackers of TOTEM (not usable at CMS lumi)
Replace T2 with a compact silicon tracker (~ CMS technology) or GEMs
Add EM/HAD calorimeter (CASTOR) behind T2
Add Zero degree calorimeter (ZDC) at 140 m
Silicon tracker or GEM tracker
Distance from IP: 13570 mm
T2 inner radius: 25 mm + 8 mm = 33mm
Vacuum chamber inner radius: 25 mm
Outer radius: 135mm
Length: 400 mm
CMS TRACKER Silicon Strip detectors :
Single side p+ strips on n-type substrate, thickness=320 mm, AC-coupled, pitch 80~205 mm, Radiation hardness up to 1.6x1014 1MeV equ./cm2, Cold enviroment –20oC.
Or an 8 plan GEM detector?
T2 h range : 5.3 < h < 6.5
Under study by TOTEM…
GEMs usable for CMS pp and HI runs?
A calorimeter in the range 5.3 << 6.8 (CASTOR)
Position of T2 and Castor (7/2/03)
Tungsten and quartz fibres
Length 152 cm~ 9I
8 sectors/ needs extension
ZDC: zero degree calorimeter
Beam pipe splits 140m from IR
Tungsten/ quartz fibre or
EM and HAD section
Funding pending in DOE
Certainly help welcome on simulation tools, detailed physics studies…
Number of overlap events versus LHC luminosity
distribution of number of interactions
1 int. 22% 4%
Doable at startup lumnosity without Roman Pots!
proton for smaller xPOM
xPomeron < 0.03
xPomeron < 0.02
xPomeron < 0.0075
Hard Single diffraction
of minimum- particle per event
rapidity gap trigger study
Detector layout/radiation hardness/occupancy/trigger/integration
Gamma-gamma /gamma-p studies/Low-x studies/Fast simulation.
Physics studies on diffraction and low-x
- Hard (& soft) diffraction, QCD and EWSB (Higgs), New Physics
- Low-x dynamics and proton structure
- Two-photon physics: QCD and New Physics
- Special exotics (centauro’s, DCC’s in the forward region)
- Cosmic Rays, Luminosity measurement, (pA, AA…)
complete forward detectors for initial LHC lumi