v.avati physics at lhc totem and diffractive physics at the lhc infn sezione di bari and politecnico...

$: V.Avati Physics at LHC TOTEM and Diffractive Physics at the LHC INFN Sezione di Bari and Politecnico di Bari, Bari, Italy Case Western Reserve University,$
V.AvatiPhysics at LHC

TOTEM and Diffractive Physics at the LHC

INFN Sezione di Bari and Politecnico di Bari, Bari, Italy Case Western Reserve University, Cleveland, Ohio,USA

CERN, Geneva, Switzerland

Estonian Academy of Sciences, Tallinn, Estonia

Università di Genova and Sezione INFN, Genova, Italy

Università di Siena and Sezione INFN-Pisa, Italy University of Helsinki and HIP, Helsinki, FinlandAcademy of Sciences, Praha, Czech RepublicWarsaw University of Technology, Plock,Poland Penn State University, University Park, USABrunel University, Uxbridge, UK

V. Avati

on behalf of the

TOTEM Collaboration

Physics at LHC

Krakow, 2-8 July 2006


Physics programPhysics program

Total cross-section with a precision of 1%Total cross-section with a precision of 1%

Elastic pp scattering in the range 10 Elastic pp scattering in the range 10 -3-3 < t = (p < t = (p))22 < 10 GeV < 10 GeV22

Soft diffractionSoft diffraction

Measurement of leading particlesMeasurement of leading particles

Particle and energy flow in the forward directionParticle and energy flow in the forward direction

Soft and hard diffraction in Single and Double Pomeron ExchangeSoft and hard diffraction in Single and Double Pomeron Exchangeproduction of jets, W, heavy flavours.....production of jets, W, heavy flavours.....

Central Exclusive particle production Central Exclusive particle production

Low-x physicsLow-x physics

and and p physicsp physics

WWIITTHH

CCM M S S


COMPETE Collaboration:

pp Total Cross-Sectionpp Total Cross-Section

Current models predict for

14 TeV: 90 – 130 mb

Aim of TOTEM: ~ 1% accuracy

Luminosity independent method:

COMPETE Collaboration fits all available hadronic data

and predicts at LHC:

PRL 89 201801 (2002)]


Experimental apparatusExperimental apparatus


• 5 planes with measurement of three coordinates per plane.

• 3 degrees rotation and overlap between adjacent planes

• Primary vertex reconstruction• Trigger with wires

3.1< || <4.7

~3 m1 arm

T1 TelescopeT1 Telescope


5.3<|| < 6.5

GEM (Gas Electron Multiplier)

10 half-planes @ 13.5m from IP5

40 cm

T2 TelescopeT2 Telescope

CASTOR Calorimeter(CMS)

Full Telescope Mock up


256 (width: 80 m,pitch: 400 m) strips

1536 pads 54() x 22() 2x2 - 7x7 mm2

x= 0.06 x 0.017L1 Trigger

pads

stripsRead-out board


Roman Pot unit:- Measurement of very small p scattering angles (few rad)- Vertical and horizontal pots mounted as close as possible- BPM fixed to the structure gives precise position of the beam- TOTEM at the RP: beam ≈ 80 m- Leading proton detection at distances down to 10 beam + d- Need “edgeless” detectors that are efficient up to the physical edge to minimize “d”

reconstructed track

Roman PotRoman Pot

4 m

10 planesSi edgeless det.

SPS Test Beam '04


Lateral Pot Vertical Pots BPM


TOTEM ROMAN POT IN CERN SPS BEAM


Detector’s ID50

m

66 μm pitch

dead

are

a

Pitch adapter on detector

Si Edgeless Detectors for RPSi Edgeless Detectors for RP

Planar technology with CTS(Current Terminating

Structure)

Test Beam 2003

2006 production

I2I1

+-

biasing ring Al

p+

n+

cut edge

current terminating

ring

Al

SiO2

n-type bulkp+

50m

AC coupled microstrips made in planar technology with

specific guard-ring design and biasing scheme. Full production by the end of 2007

First measurement of leakage current at CERN:

60 nA at 200 V (excellent)

Strong improvements on the cut at the sensitive edge

Also available another technology: 3D/planar edgeless Si-det.


Totem OpticsTotem Optics TOTEM needs special/independent short runs at high-high-* * and and low low for precise for precise measurement of the measurement of the scattering angles of a few few radrad

As consequence of high * : large beam size at IP *= √* ~ 0.3 rad

√* ~ 0.4 mm

Require parallel-to-point focusing: trajectories of proton scattered at the same angle but at different vertex locations ( y~

y)

Reduced number of bunches (43, 156) to avoid interactions further downstream

Baseline optics *=1540 m: Parallel-to-point focusing in both transverse planes, allows

very low-t detection (-t ~ 2 10-3 GeV2)

requires special injection optics

probably not available at beginning of LHC

Investigation on *=90 m : paralle-to-point focusing only in vertical plane

t detection down to ~ 2 10-2 GeV2

achievable by un-squeezing the standard LHC injection optics


1.15 (0.6 - 1.15) 1.150.3 N of part. per bunch

(x 1011)

2 x 1030

2.3

200

3.75

0

156

90

Soft &

semi-hard diffraction

2.4 x 1029

0.29 - 0.57

454 - 880

1 - 3.75

0

156

1540

Soft diffraction

3.6 x 10321.6 (7.3) x 1028Peak luminosity

[cm-2 s-1]

5.280.29 (2.3)RMS beam diverg.

[rad]

95454 (200)RMS beam size at IP [m]

3.751 (3.75)Transv. norm. emitt. [m rad]

1600Half crossing angle

[rad]

280843N of bunches

18, 2, 0.51540 (90)

large |t| elasticlow |t| elastic,

tot ,

min bias

Physics:

*[m]

Running ScenarioRunning Scenario


Elastic ScatteringElastic Scattering

Good acceptance for high-t values Parallel-to-point focusing

*=1540

*=2*=90

Log(-t) GeV2Log(-t) GeV2


Elastic ScatteringElastic Scattering

Detector distance to the beam: 1.3 mm (*=1540) 6 mm (*=90)

*=1540

*=2*=90

Log(-t) GeV2Log(-t) GeV2


Elastic scattering: resolutionElastic scattering: resolution

resolution: test collinearity of particles in the 2 arms -> background reduction

1540m

1o


Extrapolation of Elastic Cross Section to t=0Extrapolation of Elastic Cross Section to t=0

0.1 %0.2 radAngular spread

0.08 %20 mBeam -- detector alignment

0.1 %0.05 %Beam energy uncertainty

0.07 %107 eventsResolution, statistics (10h@1028):

Uncertainty inExtrapolation

Effect(=1540 m)

Theoretical models indetermination:

=1540 m < 0.1%=90 m ~ 0.5%

At =90 m some systematcs effects should be less important....

Total < 0.5 %


Inelastic Cross SectionInelastic Cross Section

The inelastic telescopes T1/T2:The inelastic telescopes T1/T2:

provide full inclusive trigger

reconstruct the primary vertex to discriminatebeam-gas and beam-beam interaction

Trigger efficiency:Trigger efficiency:

NSD : >99% SD: 82%

Extrapolation of SD cross section to large 1/M2 using d/dM2 ~ 1/M2


Total cross sectionTotal cross section

0.10.1----3030Elastic Elastic ScatteringScattering

0.020.02----11Double Double PomeronPomeron

0.10.10.30.32.82.877Double Double diffractivediffractive

0.60.62.52.5--14142 x single 2 x single diffractivediffractive

0.060.060.060.060.30.35858Minimum Minimum biasbias

Uncertainty Uncertainty after after

extrapolationextrapolation

Single Single armarm

DoubleDouble

armarm

Trigger Losses (mb)

tot/tot ~ 1 % (few % =90m) work in progress....


Elastic Scattering Cross SectionElastic Scattering Cross Section =90 =2

2E9 -

1.5E6 1E6

4E3 1.2E5

5E2 4E4

30 3E3

1 160

0.3 50

0.3pb-1 10 pb-1 ∫Ldt

Num

ber o

f even

ts (BSW

model) 2

20m


Diffractive protonsDiffractive protons

=1540

=2,0.5

Log

p/

pLog(-t) (GeV2)

=90

=1540

=90

=2,0.5

Log(M) (GeV)

diffr. protons detected 1-arm 2-armdiffr. protons detected 1-arm 2-arm (incl. SD) (incl. DPE)(incl. SD) (incl. DPE) ~50% ~30% ~50% ~30% ~90% ~80% ~90% ~80%


50%

Central Mass resolution (from protons)Central Mass resolution (from protons)

30%=1540 m =90 m

Sample of DPE events M=√12s

CMS/TOTEM common physics program

The combined coverage of CMS/Totem makes it possible to study a wide range of physics subjects in diffractive interactions – from QCD and the low-x structure of the proton, to the production of SM and MSSM Higgs.

A document describing the program is foreseen in autumn

Wide coverage in pseudorapidity + Proton(s) detection

RP 220m

FP420

=1540

=2,0.5

=90Lo

g

p/p

TOTEM CMS TOTEM

NB: Don’t be scared by the old nomenclature – diffraction, Pomeron… All of this now understood in terms of quarks, gluons and QCD

Single Diffraction

Double Pomeron Exchange

X

X

Processes characterized by 2 gluon exchange withvacuum quantum numbers (“Pomeron”)

Large Rapidity Gap(s) between the proton(s) and X

X measured by central detectors

Scattered proton(s) may be measured by Roman Pots

X=anything : dominated by soft physics SD and DPE inclusive cross sections, their s, t, MX

dependences are fundamental parameters of non-perturbative QCD. Must be measured at LHC !

X includes jets, W’s, Z’s, Higgs (!): hard processes calculable in pQCD Give info on proton structure (dPDFs and GPDs), QCD at high parton densities, multi-parton interactions etc, discovery physics some of this can only be obtained in diffractive interactions

Physics Motivation

Running scenario

pp->pX pp->pjjX pp->pjj (vector bosons pp->pXp pp->pjjXp pp->pjjp heavy quarks,Higgs...)

soft diffraction (semi)-hard diffraction hard diffraction

Cross section Luminosity

m1540 90 2 0.5

L (cm-2 s-1) 1029 1030 1032 1034

TOTEM runs Standard runs

The accessible physics is a function of the luminosity and *

Low Luminosity (<10Low Luminosity (<103232 cm cm-2-2ss-1-1): low and high ): low and high ** Measure inclusive SD and DPE

cross sections and t, MX dependence Rapidity Gap selection Forward Drell-Yan Validation of Cosmic Ray generators

High Luminosity (> 10High Luminosity (> 103232 cm cm-2-2ss-1-1) : low) : low** (routine CMS data taking)

Measure SD and DPE in presence of hard scale (dijets, vector bosons, heavy quarks): dPDF, GPD

• and p phyics

> 10> 103333 cm cm-2-2ss-1-1

Discover the SM or MSSM Higgs in central exclusive production

Physics menu

Running with TOTEM optics: large Running with TOTEM optics: large proton acceptanceproton acceptance

No pile-upNo pile-up

Pile-up not negligible:Pile-up not negligible:main source of backgroundmain source of background

Need additional forward protonNeed additional forward protondetectordetector

Example for Central Exclusive Production: H(120)->b bbar

2-jets (ET>40GeV) & single-arm RP 220m

Trigger Studies (low *) Trigger is an important limiting factor to select diffractive events (“low” pT processes)

CMS trigger bandwith limits: L1 : O(1) kHz ; HLT : O (1) Hz

Combinations of TOTEM RP with the standard CMS trigger conditions (jets, muons) : it is possible tolower the jet/muon thresholds substantially and stay in the limits

The CMS trigger menus now foresee 1% of the trigger bandwidth 12%on L1 and HLT for a dedicated diffractive trigger stream

M. Grothe et al., proceedings HERA-LHC workshop '05,and CMS Note 2006/054 & TOTEM Note 2006/01

Low luminosity: soft DPE & SD

Trigger (special optics): DPE : 2 proton trigger (anti collinearity condition) +T1/T2SD : 1 p + T1/T2 opposite

Measure cross sections, t, M dependence

Measure the central Mass via: proton(s)rap-gap relation calorimeters

• Transition from soft to semi-hard scale: in the soft sample, “contamination” of (low pT)-dijets events

=90 m in 0.3pb-1

~10M events of inclusive DPE/SD ~1K events of DPE-dijets (low pT) ~10K events of SD-dijets “

GAP (T1/T2/Calorimeter) vs ln()

Limit of direct measurement

Inclusive DPE and SD production of B mesons

pp -> B+X p (p) J/psi -> Event yields in 10 fb-1 : DPE ~ 10 SD ~ 2K

Background and pile-up effect under study

Muon trigger thresholds one limiting factor in event yield

Inclusive SD and DPE ttbar production pp->p+X+(tt)+X+p tt->bbqqttbar in semileptonic decay channel

Event yield in 10 fb-1

DPE ~ 1-100 depending on theoretical modelSD ~ 30 times larger cross-section

Heavy flavour diffractive production

Di-muon mass, signal+back., SD

Light SM/MSSM Higgs in central exclusive production

shields color chargeof other 2 gluons

Vacuum quantumnumbers “DoublePomeron Exchange”

pp->pHp

Extensive study of theoretical models & MC generators

H->bbar MH=120 GeV only few events expected in 30fb-1 and S/B ~ 0.1-1

H->WW MH>130 GeV Nev~3-6 for 30 fb-1

Background and pile-up studies in progress

Cross-section is expected to be orders of magnitude higher in MSSM model for high tan

(M)/M

4%

1.5%

Cosmic rays connection

Interpreting cosmic ray data depends on hadronic simulation programs Forward region poorly known/constrained Models differ up to a factor 2 or more

Need forward particle/energy measurements: LHC center-of-mass energy corresponds to Elab=1017 eV

Achievable at low luminosity

T1/T2/Castor

Summary

TOTEM will be ready for data-taking at the LHC start:

Measure total pp cross-section (and luminosity) with a precision of 1 % with * = 1540 m

(Possible early measurement with *=90 m)

Measure elastic scattering in the range 10-3< t < 10 GeV 2

In collaboration with CMS:

soft diffractionsemi-hard diffraction (pT > 10 GeV)

hard diffractionExclusive Double Pomeron Exchange

Studies of forward particle production

v.avati physics at lhc totem and diffractive physics at the lhc infn sezione di bari and politecnico...

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