Forward Physics with the TOTEM CMS at the LHC Risto Orava. Forward physics at the LHC Signature studies Experimental layout An example: pp p+H+p Outlook. XIII ISVHECRI Pylos, Greece, 6-12 September 2004 R.Orava.
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TOTEMCMS at the LHC
XIII ISVHECRI Pylos, Greece, 6-12 September 2004 R.Orava
Low-x Workshop, Prague 17 September 2004 Risto Orava
pp collisions at 14 TeV
LHC is built into
27 km the LEP tunnel
23 inelastic events
per bunch crossing
Planned Startup on Spring 2007
Total TOTEM/CMS acceptance (b*=1540m)
microstation at 19m?
Important part of the phase space is not covered by
the generic designs at LHC. TOTEM CMS Covers more
than any previous experiment at a hadron collider.
information value low:
- bulk of the particles crated late
information value high:
- leading particles created early
TOTEM + CMS
In the forward region (|h > 5): few particles with large energies/small
‘wee’ partons lns
Baryonic charge distribution
Valence quarks in a bag with
survival & ”underlying”
event structures are
with a geometrical
view of the scattering
- eikonal approach!
Soft diffractive scattering
Hard diffractive scattering
’Glansing’ scattering of proton fields
How to manage with the high-pT signatures in the environment of an underlying event?
initial/final gluon radiation
secondary semi-hard interactions
How do we control the kinematics (DIS vs. hh)?
Pomeron exchange (~exp Bt)
Ldt = 1033 & 1037 cm2
Studying elastic scattering an soft diffraction requires
special LHC optics. These will yield large statistics.
(* = 1540 m & 18 m)
Rel = sel(s)/stot(s)
Rdiff = [sel(s) + sSD(s) + sDD(s)]/stot(s)
Extrapolation for diffractive events needed
Loss at low masses
TOTEM will measure stot to 1%
Additional forward coverage opens up new complementary physics program at the LHC
– spin-parity of X! (LHC as the e+e- linear collider in gg-mode.)
As a Gluon Factory LHC could deliver... physics program at the LHC
longer Q physics program at the LHC2
Low-x Physics at the LHCGain in x-reach & Q2-range
Relative precision on the measurement of physics program at the LHCHBR for various channels, as function of mH, at Ldt = 300 fb–1. The dominant uncertainty is from Luminosity: 10% (open symbols), 5% (solid symbols).
(ATL-TDR-15, May 1999)
In addition: The signatures of new physics have to be normalized: The Luminosity Measurement
Luminosity relates the cross sectionsof a given process by:
L = N/s
A process with well known, calculable and large s (monitoring!) with a well defined signature? Need complementarity.
Measure simultaneously elastic (Nel) & inelastic rates (Ninel), extrapolateds/dt 0, assumer-parameter to be known:
(1+r2) (Nel + Ninel)2
Ninel = ? Need a hermetic detector.
dNel/dtt=0 = ? Minimal extrapolation to t0: tmin 0.01
Forward Physics Scenarios physics program at the LHC
total cross section
DPE Higgs, SUSY,...
& fwd jets
p± vs. po
Correlation with the CMS Signatures physics program at the LHC
To Reach the Forward Physics Goals We Need: physics program at the LHC
Need to Measure Inelastic Activity and Leading Protons physics program at the LHC
over Extended Acceptance in , , and –t.
Measurement stations (Roman Pots) at locations optimized
vs. the LHC beam optics. Both sides of the IP.
Measure the deviation of the leading proton location from the nominal beam axis () and the angle between the two measurement locations (-t) within a doublet.
Acceptance is limited by the distance of a detector to the beam.
Resolution is limited by the transverse vx location (small ) and by
beam energy spread (large ).
For Higgs, SUSY etc. heavier states need LP4,5 at 300-400m!
TOTEM ROMAN POT IN CERN TEST BEAM physics program at the LHC
Microstation – Next Generation Roman Pot physics program at the LHC
Silicon pixel detectors in
A solution for 19m, 380 & 420m?
Diffraction at high physics program at the LHCb*: Acceptance
Luminosity 1028-1030cm-2s-1 (few days or weeks)
CMS tracking is extended by forward telescopes physics program at the LHC
on both sides of the IP
T1-CSC: 3.1 < h < 4.7
T2-GEM: 5.3 <h< 6.5
T3-MS: 7.0 <h< 8.5 ?
- A microstation (T3) at 19m is an option.
Running Scenarios 1: High & Intemediate physics program at the LHCb*
- low b* physics will follow...
The process: pp physics program at the LHC p + H + p
MH2 = (p1 + p2 – p’ – p”)2 x1x2s (at the limit, where pT’ & pT” are small)
x1 = 1-p’q1/p1q1 1-p’/p1x2 = 1-p”q2/p2q2 1-p”/p2
Leading proton studies at low physics program at the LHC*
A study by the Helsinki group in TOTEM.
Central Diffraction produces two leading protons, physics program at the LHC
two rapidity gaps and a central hadronic system. In the
exclusive process, the background is suppressed and the
central system has selected quantum numbers.
Survival of the rapidity gaps?1
JPC = 0++ (2++, 4++,...)
Measure the parity P = (-1)J:
ds/d 1 + cos2
Mass resolution S/B-ratio
1 V.A.Khoze,A.D.Martin and M.G.Ryskin, hep-ph/0007359
The Experimental Signatures: physics program at the LHC
pp p + X + p
- vertex position in the transverse plane?
- resolution in x ?
-beam energy spread?
Aim at measuring the:
Leading Proton Detection physics program at the LHC
x = 0.02
Jerry & Risto
Mass Acceptance physics program at the LHC
Both protons are seen with 45 % efficiency at MX = 120 GeV
Some acceptance down to: MX = 60 GeV
308m & 420m locations select symmetric proton pairs acceptance decreases.
pp p + X + p
MX = 120 GeV
MX = 60 GeV
Momentum loss resolution at 420 m physics program at the LHC
Resolution improves with increasing momentum loss
Dominant effect: transverse vertex position (at small momentum loss) and beam energy spread (at large momentum loss, 420 m)/detector resolution (at large momentum loss, 215 m & 308/338 m)
proton momentum loss
proton momentum loss
DPE Mass Measurement at 400m physics program at the LHC
Gaussian s(M) vs. central mass
assuming DxF/xF = 10-4
s(M) = (1.5 - 3.0) GeV (DxF/xF = (1-2)10-4)
65% of the data
20 GeV < MX < 160 GeV
(MXmax determined by the aperture of
the last dipole,B11,
MXmin by the minimum deflection = 5mm)
Central Mass (GeV)
Helsinki group/J.Lamsa & R.O.
SUMMARY: physics program at the LHC
TOTEM opens up Forward Physics to the LHC
TOTEMCMS covers more phase space than any previous experiment at a hadron collider.