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, 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, Finland Academy of Sciences, Praha, Czech Republic Warsaw University of Technology, Plock,Poland Penn State University, University Park, USA Brunel University, Uxbridge, UK V. Avati on behalf of the TOTEM Collaboration Physics at LHC Krakow, 2-8 July 2006

V.Avati Physics at LHC Total cross-section with a precision of 1% Elastic pp scattering in the range < t = (pq) 2 < 10 GeV 2 Soft diffraction Soft diffraction Measurement of leading particles Particle and energy flow in the forward direction Soft and hard diffraction in Single and Double Pomeron Exchange production of jets, W, heavy flavours..... Central Exclusive particle production Low-x physics gg and gp physics WIWITHTHCMSCMSWIWITHTHCMSCMS

V.Avati Physics at LHC COMPETE Collaboration : 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 (2002)]

V.Avati Physics at LHC

V.Avati Physics at LHC 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< |h| <4.7 ~3 m 1 arm

V.Avati Physics at LHC

V.Avati Physics at LHC 5.3<|h| < 6.5 GEM (Gas Electron Multiplier) m from IP5 40 cm CASTOR Calorimeter(CMS) Full Telescope Mock up

V.Avati Physics at LHC 256 (width: 80 mm,pitch: 400 mm) strips 1536 pads 54(f) x 22(h) 2x2 - 7x7 mm 2 Dh x Df = 0.06 x 0.017p L1 Trigger pads strips Read-out board

V.Avati Physics at LHC Roman Pot unit: - Measurement of very small p scattering angles (few mrad) - Vertical and horizontal pots mounted as close as possible - BPM fixed to the structure gives precise position of the beam - TOTEM at the RP: s beam ≈ 80 mm - Leading proton detection at distances down to 10 s beam + d - Need “edgeless” detectors that are efficient up to the physical edge to minimize “d” reconstructed track 4 m 10 planes Si edgeless det. SPS Test Beam '04

V.Avati Physics at LHC Lateral Pot Vertical Pots BPM

V.Avati Physics at LHC TOTEM ROMAN POT IN CERN SPS BEAM

V.Avati Physics at LHC Detector’s ID 50 mm 66 μm pitch dead area Pitch adapter on detector Planar technology with CTS (Current Terminating Structure) Test Beam production I2I2 I1I1 + - biasing ring Al p+p+ n+n+ cut edge current terminating ring Al SiO 2 n-type bulk p+p+ 50 mm 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.

V.Avati Physics at LHC high-b* and low e for precise measurement of the few mrad TOTEM needs special/independent short runs at high-b* and low e for precise measurement of the scattering angles of a few mrad As consequence of high b* : large beam size at IP s q* = √e/b* ~ 0.3 mrad s*=√e b* ~ 0.4 mm Require parallel-to-point focusing: trajectories of proton scattered at the same angle but at different vertex locations (  y~ Q * y ) Reduced number of bunches (43, 156) to avoid interactions further downstream Baseline optics b*=1540 m: Parallel-to-point focusing in both transverse planes, allows very low-t detection (-t ~ GeV 2 ) requires special injection optics probably not available at beginning of LHC  Investigation on b*=90 m : paralle-to-point focusing only in vertical plane t detection down to ~ GeV 2 achievable by un-squeezing the standard LHC injection optics

V.Avati Physics at LHC 1.15( ) N of part. per bunch (x ) 2 x Soft & semi-hard diffraction 2.4 x Soft diffraction 3.6 x (7.3) x Peak luminosity [cm -2 s -1 ] (2.3)RMS beam diverg. [mrad] (200)RMS beam size at IP [mm] (3.75)Transv. norm. emitt. [mm rad] 1600Half crossing angle [mrad] N of bunches 18, 2, (90) large |t| elasticlow |t| elastic, s tot, min bias Physics: b*[m]

V.Avati Physics at LHC Good acceptance for high-t values Parallel-to-point focusing b*=1540 b*=2 b*=90 Log(-t) GeV 2

V.Avati Physics at LHC Detector distance to the beam: 1.3 mm (b*=1540) 6 mm (b*=90) b*=1540 b*=2 b*=90 Log(-t) GeV 2

V.Avati Physics at LHC f resolution: test collinearity of particles in the 2 arms -> background reduction 1540m 1o1o

V.Avati Physics at LHC 0.1 %0.2 mradAngular spread 0.08 %20 mmBeam -- detector alignment 0.1 %0.05 %Beam energy uncertainty 0.07 %10 7 eventsResolution, statistics 28 ): Uncertainty in Extrapolation Effect (b=1540 m) Theoretical models indetermination: b=1540 m < 0.1% b=90 m ~ 0.5% At b=90 m some systematcs effects should be less important.... Total < 0.5 %

V.Avati Physics at LHC The inelastic telescopes T1/T2: provide full inclusive trigger reconstruct the primary vertex to discriminate beam-gas and beam-beam interaction Trigger efficiency: NSD : >99% SD: 82% Extrapolation of SD cross section to large 1/M 2 using ds/dM 2 ~ 1/M 2

V.Avati Physics at LHC Elastic Scattering Double Pomeron Double diffractive x single diffractive Minimum bias Uncertainty after extrapolation Single arm Double Double s arm s arm Trigger Losses (mb) Ds tot /s tot ~ 1 % (few % b=90m) work in progress....

V.Avati Physics at LHC b=90 b=2 2E E6 1E6 4E3 1.2E5 5E2 4E4 30 3E pb pb -1 ∫Ldt Number of events (BSW model) 220m

V.Avati Physics at LHC b=1540 b=2,0.5 Log(x) x=Dp/p Log(-t) (GeV 2 ) b=90 b=1540 b=90 b=2,0.5 Log(M) (GeV) diffr. protons detected 1-arm 2-arm (incl. SD) (incl. DPE) (incl. SD) (incl. DPE) ~50% ~30% ~90% ~80% ~90% ~80%

V.Avati Physics at LHC 50% 30% b=1540 m b=90 m Sample of DPE events M=√x 1 x 2 s

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 b=1540 b=2,0.5 b=90 Log(x) x=Dp/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 with vacuum 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, M X 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 b (m) L (cm -2 s -1 ) TOTEM runs Standard runs The accessible physics is a function of the luminosity and b*

Low Luminosity (<10 32 cm -2 s -1 ): low and high b* Measure inclusive SD and DPE cross sections and t, M X dependence Rapidity Gap selection Forward Drell-Yan Validation of Cosmic Ray generators High Luminosity (> cm -2 s -1 ) : low b* (routine CMS data taking) Measure SD and DPE in presence of hard scale (dijets, vector bosons, heavy quarks): dPDF, GPD gg and gp phyics > cm -2 s -1 Discover the SM or MSSM Higgs in central exclusive production Physics menu Running with TOTEM optics: large proton acceptance No pile-up Pile-up not negligible: main source of background Need additional forward proton detector

Example for Central Exclusive Production: H(120)->b bbar 2-jets (E T >40GeV) & single-arm RP 220m Trigger Studies (low b*) 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 to lower 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/T2 SD : 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 b=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(x) s(x)/x ~ 40% Limit of direct x measurement s(x)/x ~ 80%

Inclusive DPE and SD production of B mesons pp -> B+X p (p) J/psi -> m+m- 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->bbqqmn m  ttbar in semileptonic decay channel Event yield in 10 fb -1 DPE ~ depending on theoretical model SD ~ 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 charge of other 2 gluons Vacuum quantum numbers “Double Pomeron Exchange” pp->pHp Extensive study of theoretical models & MC generators H->bbar M H =120 GeV only few events expected in 30fb -1 and S/B ~ H->WW M H >130 GeV N ev ~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 tanb s(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 E lab =10 17 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 b * = 1540 m (Possible early measurement with b*=90 m) Measure elastic scattering in the range < t < 10 GeV 2 In collaboration with CMS: soft diffraction semi-hard diffraction (p T > 10 GeV) hard diffraction Exclusive Double Pomeron Exchange Studies of forward particle production