TOTEM Physics Scenarios at the LHC; Elastic Scattering, Total Cross section, Diffraction,

$Page 1: TOTEM Physics Scenarios at the LHC; Elastic Scattering, Total Cross section, Diffraction,$
1XXXV ISMD 2005 KROMĚŘÍŽ , CZECH 9.-15.8.2005

TOTEM Physics Scenarios at the LHC; Elastic Scattering, Total Cross section, Diffraction, and beyond ...

Risto Orava HIP & UH

2

TOTEM Experiment

CMS Experimental Area (IP5)

Leading Protons measured at+147m & +220m from the CMS

Leading Protons measured at-220m & -147m from the CMS

(Also CMS is here...)

• Leading protons are detected at 147m & 220m from the IP.• CMS coverage is extended by Totem T1 and T2 spectrometers.• Additional forward calorimetry & veto counters are under planning.

CMS is TOTEMized...

XXXV ISMD 2005, KROMĚŘÍŽ , CZECH Risto Orava 12.8.2005

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Configuration of the Experiment

b-jet

b-jet

CMS

- Leading protons on both sides down to 1‰- Rapidity gaps on both sides – forward activity – for || > 5- Central activity in CMS

-

Aim at measuring the:

Roman PotStation at147 / 220m

Aim at detecting colour singlet exchange processes with the leading protonsscattered at small angles with respect to the beam.

Roman PotStation at147/220mCASTORT1T1T2 T2

Services routing:

From Castor to Racks

Patch Panels

T2 Services routing:


Patch Panels

T2Services routing:


Patch Panels

T2 Services routing:


Patch Panels

T2

CASTOR


4

0-12 -10 -8 -6 -4 -2 +2 +4 +6 +8 +10 +12

pT (

GeV

)

0.1

1

10

100

1000 CMSATLAS

ALIC

E

LH

Cb

Base Line LHC Experiments: pT- coverage

Exp B (T)

pT

(GeV)

ALICE 0.2-0.5 0.1-0.25

ATLAS 2.0 0.5

CMS 4.0 0.75

LHCb 4Tm 0.1

The base line LHC experiments will cover the central rapidity region- TOTEMCMS will complement the coverage in the forward region.

T1T1

T2 T2

RP RP

LHC TOTEMized

mic

rosta

tion

mic

rosta

tion

vetoveto pTmax ~ s exp(-)


5

ATLAS & CMS:• Energy flow in || 5• Minimum bias event structure

• need to sort out the pile-up events at L › 1033

• present MC models differ by large factors

ALICE:• Charged multiplicities in -5 3• Zero Degree Calorimetry (neutral & charged)

TOTEM:• Charged multiplicities: 3 7 • Leading particle measurement:

• Totem sees ~ all diffractively scattered protons

• TOTEM/CMS inelastic coverage is unique: • Holes only at ~ 5 & 7-9 (could be covered with s & veto counters)

Base Line LHC Experiments


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Diffractive scattering is a unique laboratory of confinement & QCD: A hard scale + hadrons which remain intact in the scattering process.

Soft diffractive scattering:-large b

Hard diffractive scattering- small b

Valence quarks in a bag with

r 0.1fm

Baryonic charge distribution-r 0.5fm

Rapidity gapsurvival & ”underlying”event structures areintimately connectedwith a geometricalview of the scattering- eikonal approach!

Longitudinal view- Lorentz contracted – not to scale!

p

p

lnMX2

jet

jet

Elastic soft SDE

hard SDE

hard CD

Totem sees SDE MX 20 GeV

lns

rapid

ity

Cross sections are large.

10mb?25mb? 1mb?

Hard processes:Jet momenta correlated with the initial parton momenta.

Soft processes:Coherentinteractions-impact parameterpicture.

+

Transversal view

‘wee’ parton cloud - grows logarithmically

b b

soft CD


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With the leading protons and additional forward coverage a new physics realm opens up at the

LHC:

• Hard diffraction with multi- rapidity gap events (see: Hera, Tevatron, RHIC...) Problems intimately related to confinement.

– Gluon density at small xBj (10-6 – 10-7) – “hot spots” of glue in vacuum?

– Gap survival dynamics, proton parton configurations (pp3jets+p) – underlying event structures– Diffractive structure: Production of jets, W, J/, b, t, hard photons,– Parton saturation, BFKL dynamics, proton structure, multi-parton scattering– Studies with pure gluon jets: gg/qq… LHC as a gluon factory! (see: KMR EPJC19(2001)477)

• Signals of new physics based on forward protons + rapidity gaps Threshold scan for JPC = 0++ states in: pp p+X+p

– Spin-parity of X ! (LHC as the pre -e+e- linear collider in the -mode.)

• Extend ‘standard’ physics reach of the CMS experiment into the forward region: Full Monty!

• Measure the Luminosity with the precision of L/L 5 % (KMRO EPJC19(2001)313)

0 0c bχ , χ

Elastic scattering, tot and soft diffraction – surely...But also:


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As a Gluon Factory LHC could deliver...• High purity (q/g ~ 1/3000) gluon jets with ET > 50 GeV;

• gg-events as “Pomeron-Pomeron” luminosity monitor

• Possible new resonant states in a background free environment (bb, W+W- & +- decays); (see: KMR EPJC23(2002)311)

• Higgs• glueballs• quarkonia 0++ (b )• gluinoballs• invisible decay modes of Higgs (and SUSY)!?• CP-odd Higgs

• Squark & gluino thresholds are well separated• practically background free signature: multi-jets & ET

• model independence (missing mass!) [expect O(10) events for gluino/squark masses of 250 GeV]• an interesting scenario: gluino as the LSP with mass window 25-35 GeV(S.Raby)

• Events with isolated high mass pairs

• Moreover: Mini-Black Holes, Extra Dimensions – The Brane World !!!... (see: Albrow and Rostovtsev)

gg

-


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Probing Very Small-x Gluons

Instrument region with tracking,calorimetry (em+had), muons,jets, photons ...

0 00.5 3 /J

1Bj T

jets

x E es

1 iT

particles

E es

In SD: If a pair of high ET jets are produced, then:

If the interacting partons have fractional momenta of P, then =xBj/,then (if all hadrons i in the event are measured):

Consider a high momentum proton: Measure gluon distribution G(x,Q2) at fixed Q2 and small x with x››Q probe gluons with the transverse size = |b|~1/Q and longitudinal size = |z|~1/px. gluon saturation, colour-glass condensates, colour-dipoles,....


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Central Diffraction produces two leading protons, two rapidity gaps and a central hadronic system. In the exclusive process, the background is suppressed and the central system has selected quantum numbers.

JPC = 0++ (2++, 4+

+,...)

Gap GapJet+Jet

min max

Survival of the rapidity gaps?1

see: DKMOR EPJC25(2002)391

Measure the parity P = (-1)J:d/d 1 + cos2

Mass resolution S/B-ratio

MX212s

Also: Jet energy scale calibration? – M. AlbrowXXXV ISMD 2005, KROMĚŘÍŽ , CZECH Risto Orava 12.8.2005

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Signatures• Proton (Roman Pots):

• elastic proton (*=1540m: 5 10-4 -t 1 GeV2, *=18m: 310-1 -t 10 GeV2)

• diffractive proton (*=1540m: 90% of all diffractive protons: 10-2 & -t 10-3 GeV2)

• hard diffractive proton (* = 0.5m: excellent coverage in -t space)

• Rapidity Gap (T1 & T2, Castor & ZDC):• rapidity gaps (up to L~ 1033cm-2 s-1: 3 || 7, +veto counters?)

• Very Fwd Objects (T1 & T2, Castor & ZDC):• Jets (up to L~ 1033cm-2 s-1: 3 || 7, +veto counters?)

• , e, (fwd em calorimetry & muons: 3 || 7)

• tracks (vx constraints & pattern recognition: 3 || 7)

• particle ID?

• Correlation with CMS Signatures (central jets, b-tags,...)


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Correlation with the CMS Signatures

• e, , , , and b-jets:• tracking: || < 2.5• calorimetry with fine granularity: || < 2.5• muon: || < 2.5

• Jets, ETmiss

• calorimetry extension: || < 5

• High pT Objects• Higgs, SUSY,...

• Precision physics (cross sections...)• energy scale: e & 0.1%, jets 1% • absolute luminosity vs. parton-parton luminosity via

”well known” processes such as W/Z production?


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• Leading Protons

• Extended Coverage of Inelastic Activity

• CMS

To Reach the Forward Physics Goals Need:


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Leading Protons - Measurement

RP1RP1 RP2RP2 RP3RP3

220 m220 m180 m180 m

147 m147 m

IP5 CMS Interaction PointTAS Beam Absorber for secondaries between the IP and Q1Qi Quadrupole MagnetsTASA Beam Absorber for secondaries between Q1 and Q2TASB Beam Absorber for secondaries between Q2 and Q3DFBx Cryogenic Electrical Feed-Boxfor ArcDi Dipole Magnet iTAN Beam Absorber for neutral secondaries before Q1-Q3BSR Synchrotron Radiation Observation SystemTCL Long Collimator for protecting Quadrupole Magnets

The small-angle protons are detected within the LHC beam pipe at large distances from the IP. To facilitate detection of elastically and diffractively scattered protons, special machine optics are needed * = 1540m (-t down to 10-3 GeV2), 18m (-t up to 10 GeV2)For hard diffraction and low-x physics, nominal – high luminosity – conditions are required * = 0.5m

RPi: Special insertion devices needed for placing the proton detectors within the beam pipe Roman Pots

CMSCMS


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Leading Proton Detection-An Example 147m 180m 220m0m 308m 338m 420 430m

IP

Q1-3

D1

D2 Q4 Q5 Q6 Q7 B8 Q8 B9 Q9 B10 B11Q10

Helsinki group: Jerry Lamsa & RO

= 0.02

Note the magnification x vs. z!


16

Pomeron exchange ~ e–B|t|

diffractive structure

Photon - Pomeron interference

L dt = 1033 and 1037 cm-2

pQCD ~ |t|–8

Elastic Scattering: d/dtd/

dt

(mb/G

eV

2)

-t (GeV2)

-tmin ~ 2 · 10-3 GeV2

-tmax ~ 10 GeV2

extrapolateto – t = 0!


17

Coulomb region 510-4 [lower s, RP closer to beam]Interference, meas. 510-4 510-3 [as above], standard * = 1540 mPomeron exchange 510-3 0.1 * = 1540 mDiffractive structure 0.1 1 * = 1540 m, 18 mLarge |t| – perturb. QCD 1 10 * = 18 m

Region |t| [GeV]2 Running Scenario

Elastic Scattering: Acceptance in -t


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Extrapolation of Elastic Cross-Section to t = 0

Effect Extrapolation uncertainty

Statistics (10h @ 1028): 107 events

0.07 %

Uncertain functional form of d/dt

0.5 %

Beam energy uncertainty

0.05 % 0.1 %

Beam / detector offset 20 m 0.08 %

Crossing angle 0.2 rad 0.1 %

Total 0.53 %Non-exponential d/dt fitted to

Slope parameter

according to BSW Model

tBftf e)( 0

dtdf

tftB

1

see: KMRO EPJ(2001)313


19

~ 90 % of all diffractive protons are seen in the Roman Pots -assuming

= p/p can be measured with a resolution of ~ 5 x 10-3 .

Soft Diffractive Protons (high *)

A < 5 %

A > 95 %

85 - 95 %

* = 1540 m

t

dtd

d 10e1


20

Hard Diffraction (high *): Acceptance


21

Measurement of tot- Luminosity-independent measurement of the total cross-

section by using the Optical Theorem:

02

2

1

16

t

eltot dt

dN

L

ineleltot NN L inelel

teltot NN

dtdN

0

2

)/(

1

16

• Measure the elastic and inelastic rate with a precision better than 1%.• Extrapolate the elastic cross-section to t = 0.

Or conversely:Extract luminosity:

0

22

|/16

1

tel

inelel

dtdN

NN

L


22

T1: 3.1 << 4.7

T2: 5.3 < < 6.5

T1T1T2T2

10.5 m

10.5 m~14 m CASTORCASTOR

Need Extension to Inelastic CoverageTo measure the colour singlet exchange, need to extend central detectorcoverage in the forward direction: > 5.


23

Measurement of the Total Rate Nel + Ninel

[mb]

T1/T2 double arm trigger loss

[mb]

T1/T2 single arm

trigger loss [mb]

Uncertainty after

extrapolation [mb]

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 ~ 0.2(using leading p and CMS)

0.02

Elastic Scattering 30 - - 0.15

Acceptancesingle diffraction

simulated

extrapolateddetectedLoss at low

masses

Extrapolation of diffractive cross-section to large 1/M2 using d/dM2 ~ 1/M2 .

Total: 0.8 %

50% acceptance down to 3.5 (1.5) GeV

Model uncertainties are large!XXXV ISMD 2005, KROMĚŘÍŽ , CZECH Risto Orava 12.8.2005

24

Accuracy of tot

%1005.0008.0005.0 222 tot

tot

Extrapolation to t = 0 Total rate Nel + Ninel = 0.12 ± 0.02


25

Total Cross Section - TOTEM

TOTEM

tot (lns)

as s = 0, 1, 2, or- 0.08 ??


26

Elastic Scattering- TOTEM

TOTEM


27

Diffractive Mass Acceptance

TOTEM ’base line’

+veto counters


28

Towards Hard Diffraction- Tevatron resultsjets, heavy quarks, heavy bosons produced at ~ 1% of the inclusive rate


29

Running ScenariosScenario(goal)

1low |t| elastic,tot , min.

bias

2diffractive physics,large pT

phenomena

3intermediat

e |t|, hard

diffraction

4large |t| elastic

* [m] 1540 1540 200 - 400 18

N of bunches 43 156 936 2808

Half crossing angle [rad]

0 0 100 - 200 160

Transv. norm. emitt. [m

rad]

1 1 3.75 3.75 3.75

N of part. per bunch

0.3 x 1011 0.6 x 1011

1.15 x 1011

1.15 x 1011 1.15 x 1011

RMS beam size at IP

[m]

454 454 880 317 - 448 95

RMS beam diverg. [rad]

0.29 0.29 0.57 1.6 - 1.1 5.28

Peak luminosity[cm-2 s-1]

1.6 x 1028 2.4 x 1029 (1 - 0.5) x 1031

3.6 x 1032

+ Runs at * = 0.5 m, L = (1033 1034) cm-2 s-1 foreseen as an extension to the TOTEM program.XXXV ISMD 2005, KROMĚŘÍŽ , CZECH Risto Orava 12.8.2005

30

Exciting new physics potential in the process: pp p (JPC=0++) p

p

p

jet

jet

p

p

p

p

jet

jet0

5

-5

10

-10

P

P

-Colour singlet exchange process with exclusive priviledges - JPC selection rule e+e- ILC type threshold scan for new physics!

see: KMR EPJ(2002)

- Need to solve the L1 trigger issue at high luminosity (pile-up) conditions.


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Exclusive Production by CED: 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

Particle excl Decay channel BRRate at

2x1029 cm-2 s-1

Rate at

1031 cm-2 s-1

(no acceptance / analysis cuts)

c0

(3.4 GeV)3 b [KMRS]

J/ +–

+ – K+ K–

6 x 10-4

0.018

1.5 / h

46 / h

62 / h

1900 / h

b0

(9.9 GeV)4 nb [KMRS] +– 10-3 0.07 / d 3 / d

H

(120 GeV) 3 fb (2.5fb) bb 0.68 0.02 / y 1 / y

Need L ~ 1033 cm-2 s-1 for Higgs, i.e. a running scenario for * = 0.5 m:• try to modify optics for enhanced dispersion,• try to move detectors closer to the beam,• install additional Roman Pots in cold LHC region at a later stage.XXXV ISMD 2005, KROMĚŘÍŽ , CZECH Risto Orava 12.8.2005

32

Hard Diffractive Protons (Low *)

CMS

Disp

ersio

n in

horizo

nta

l pla

ne

(m)

x

Opti

cal fu

nct

ion

in x

and y

(m

)

For a 2.5 mm offset of a 0.5 % proton, need dispersion 0.5 m.

Proton taggers to be located at > 250 m from the IP (i.e. in a ”cryogenic section” of the LHC).

y

Dx

horizontal offset = Dx ( = momentum

loss)


33

Dispersion suppressor

Matching section

Separation dipoles Final focus

Potential locations for measuring the leading protons in pp p X p with MX ~ O(100 GeV).

420 m 220 m CMS(308/338m)

Cryogenic (”cold”) region (with main dipole magnets)

locations of currently planned TOTEM pots!!


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Leading protons: Hard Central Diffraction

Uncertainties included in the study:

• Initial conditions at the interaction point

• Conditions at detector location

Position resolution of detector (x,y = 10 m) Resolution of beam position determination (x,y = 5 m)

Off-sets at detector locations

• pp p + X + p simulated using PHOJET1.12& ExHuME

• Protons tracked through LHC6.2& 6.5 optics using MAD

Transverse vertex position (x,y = 11 m)

Beam energy spread (E = 10-4) Beam divergence ( = 30 rad)

J.Lamsa, T. Maki, R.Orava, K.Osterberg...

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Acceptance: ExHuME vs. PHOJET

50%

33%

"420+220" calculation: either both protons are detected at 420m, or both protons are detected at 220m, or one proton is detected at 420 [220]m with the other one detected at 220 [420]m.

24%

12%


see Marek Tasevsky’s talk on Monday

36

Resolution: ExHuME vs. PHOJET

ExHuME 420+220m

ExHuME 420m

PHOJET 420m

PHOJET 420+220m

2.8%

0.9%

3.7%

Helsinki group: J.Lamsa (parametrisations of the MAD simulation results of T. Mäki by RO)

420m+220m ExHuME420m ExHuME420m+220m PHOJET420m PHOJET

Helsinki group: Jerry Lamsa et. al.


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TOTEM Physics ScenariosProton

* (m)

rapiditygap L(cm-2s-1)

jetinelasticactivity

,e,, , ++,...

elastic scattering

total cross section

soft diffraction

hard diffraction

’1540’ ’18’

’1540’

’1540’ ’170’

’170’ ’ 0.5’

low-x physics

exotics (DCC,...)

CED Higgs, SUSY,...central pair

central & fwd

inelasticacceptance gap survival

jetacceptance di-jet backgr

b-tag, ,J/,...

1028 -1032

1029 -1031

1028 -1033

1031 -1033

1031 -1033

TOTEM& CMS

TOTEM& CMS

TOTEM& CMS

central& fwd jets

di-leptonsjet-

mini-jetsresolved?

± vs. o

multiplicity

leptons’s

jetanomalies?

W, Z, J/,...

, K±,,...

’0.5’

1031 -1033

1031 -1033

’170’ ’0.5’

’170’ ’0.5’

mini-jets?

beam halo?

trigger


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TOTEM Physics Scenarios at the LHC; Elastic Scattering, Total Cross section, Diffraction,

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