0/11 Precision Measurements of the Standard Model and Searches for New Physics at CDF and ATLAS Aidan Robson Glasgow University

1/11 Hadron collider physics Origin of mass – Higgs mechanism? Beyond the Standard Model – SUSY? Extra dimensions?

2/11 Tevatron / CDF LHC / ATLAS exploit new data at energy frontier  new, unique, precision Standard Model measurement targeted directly at LHC  innovative search for new physics accelerate first physics results  indirectly, through Tevatron measurements  directly, applying techniques from Tevatron to characterise detector and pursue analysis Resulting understanding is essential before LHC ‘discoveries’ now: 10x statistics of top quark discovery; will double or triple by 2007 very exciting prospects Collider Detector at Fermilab A Toroidal LHC ApparatuS

3/11 p pTpT pZpZ antiprotonproton y  1/2 ln E+pzE–pzE+pzE–pz d 2  (pp  Z) dp T dy CDF 0<|y|<11<|y|<22<|y|<3 d  /dp T p T Z CDF: d  /dp T p T Z d  /dp T p T Z [~angular variable] Distribution different for different y?

4/11 p T (Z) / GeV d  /dp T / nb/GeV all y|y| > 2 pp  Z 0 X, Tevatron :√s=1.96TeV d  /dp T / pb/GeV CDF e+e+ e–e– Nadolsky et al:  global fits to HERA and fixed-target data suggest increased intrinsic p T carried by proton constituents, for interactions involving only a small fraction of proton’s momentum  they insert extra factor in differential cross-section ; p T (Z) broadened at high y

5/11 p T (Z) / GeV d  /dp T / nb/GeV d  /dp T / pb/GeV pp  Z 0 X  e + e – X, LHC :√s=14TeV pp  W + X  e +, LHC :√s=14TeV |y e | < 2.5 p T e > 25 GeV |y e | < 2.5 p T e > 25 GeV E T > 25 GeV ATLAS e+e+ e–e–  LHC: beam energies ~7x higher than Tevatron  Probing new part of phase space  Tevatron forward detectors map on to LHC central detectors Problem! W/Z production is a benchmark

6/11 CDF e+e+ e–e– only now have enough statistics – with 1/fb recorded now, have O(35k) events like this; of which O(10k) have |y|>2  statistical uncertainty < 3% p T (Z) / GeV d  /dp T / pb/GeV |y(Z)| > 2 pp  Z 0 X, √s=1.96TeV Challenges at CDF:  knowledge of detector material count, energy scale  uncertainties introduced by proton parton distribution fns  handling backgrounds close to beampipe – I have achieved 2% understanding for 1<|y|<2 – will extend techniques to |y|>2 (Z)

7/11 Precise, high statistics measurement with mature, well-understood detector;  tells us something new about the proton (intrinsic p T )  directs our expectations for LHC startup Will also yield:  – tune theoretical calculations; reduce m W uncertainty; in turn constrain m H  – reduce extrapolation uncertainty between J/  and Z to the W boson; reduce m W uncert. d  (pp  Z) dp T d 2  (pp  Z/  *) dp T dm also use for searches

8/11 d  /dm m ll / GeV d 2  (pp  Z/  *) dp T dm d  /dp T p T ll low mass Z pole high mass d  /dp T p T ll d  /dp T p T ll SUSY? Z ’ / extra dims? New ideas:  Ratios of p T distributions?  Cumulative integrals of p T distributions? Measure in mass bins; search in high-p T tails control dilepton

9/11 ATLAS commissioning and startup W and Z decays to leptons: golden channels for detector understanding Apply skills and techniques from CDF :  calorimeter calibration  development of lepton reconstruction  trigger efficiency measurement – all areas where I have experience and expertise; underlie all physics measurements using leptons Bring together all of these elements in first physics measurements

10/11 First ATLAS physics  Z (&W) production cross-section – foundation measurement  Z rapidity distribution – how well has description of proton extrapolated to 14TeV?  Search for Z ’ decaying to two leptons predicted by many new physics models resonant peak on small background visible even without ultimate detector performance mass of 1-2TeV should be detectable with few months’ data; analysis feasible in time-scale of fellowship starting in 2006.

11/11 Ambitious programme of measurements I am established at CDF:  Thesis was first measurement to rely on absolute scales and acceptances of new forward detectors; cross-section measurements unprecedented in precision for hadron collider. Since then at CDF:  Until recently I have been CDF Offline Operations Manager – calibrations/processing made data available; given me new technical skills that will help analysis  I am co-convener of the W/Z working group  Also in next six months contributing to H  WW analysis At ATLAS:  So far my contribution has been to hardware  Glasgow group is very strong and an ideal environment to start physics – my programme is achievable

12/11 Proposed work:  exploits wealth of new Tevatron data  accelerates understanding of new LHC detectors first LHC physics output  leads us to the major goals of hadron collider physics over the next 5-10 years

13/11

14/11 Tevatron lumi

15/ LHC: first collisions mid-07 l=10 30 cm -2 s -1, L~10pb -1 EW rates still significant: ~10 5 Z, 10 6 W, 10 5 tt, 10 7 jets Commission detector Lepton reconstruction Jet Energy Scale from Ws from top decays 2008 First physics data, l= cm -2 s -1 Commissioning L~0.5fb -1 of good data 2009 l=10 33 cm -2 s -1, L~10fb -1 ATLAS timetable Atlas timetable

16/11  =2  = m tracker had cal hadronic cal EM cal had cal solenoid pre-radiatorshower max silicon EM cal  =1 CDF

17/11 Silicon Tracking Detectors Central Drift Chambers Solenoid Coil EM Calorimeter Hadronic Calorimeter Muon Drift Chambers Muon Scintillator Counters Steel Shielding polar angle    = 1.0  = 0.6  = 2.0 CDF

18/11 Atlas

19/11 Nadolsky

20/11 ‡ Hamberg et al., Nucl.Phys. B359, 343 Harlander et al., Phys.Rev.Lett. 88, . Br(Z/  *  ee) =  3.9 (stat)  5.5 (sys)  15.3 (lum) pb (CDF, 72pb -1, winter 04 ) 66<m ll <116 GeV/c 2 NNLO Z/  * (66<m ll <116) ‡ : 252  9 pb total background 62  18 acceptance 31.9  0.4 % efficiency 71.3  1.2% kinematic/geometric lepton ID, trigger… partly statistical in nature .Br(Z  ee) s.Br(Z->ee)

21/ ±0.024 NNLO (PDG) From LEP: (3.366 ± )% R e =  0.18 (stat)  0.16 (sys) (CDF, 72pb -1, winter 04 ) R =  0.15 (stat)  0.14 (sys) (CDF, 72pb -1, winter 04 ) electrons electrons + muons  (W) = 2071  40 MeV world average: 2092  42 MeV + SM value for  W (l ) NNLO calc  0.4 MeV (PDG) R and extraction of  (W) R and Gamma(W)

22/11 PDF uncertainties – can see uncertainty from truncation of d  /dy – change shape of differential cross-sections d  /dy y central–central only central–central + central–forward different PDF sets ‘integrate out’ PDF differences ‘central– central’ ‘central– forward’ PDF uncertainties

23/11 dsdy at LHC

24/11 Higgs

25/11 p T Z arises from recoil against QCD radiation – significant non-perturbative contribution