Department of Physics LHC physics Dr Alan J Barr For the TeV-scale physics group

22nd June 2011 LHC Physics Oxford: Synonymous with subatomic physics  Frederic Soddy (1877–1956)  Transmutation: “The interpretation of Radium”  Dick Dalitz ( )  “I used to know all the data; at one time I knew every event…”  Denys Wilkinson (1922-)  Creation of the Nuclear physics laboratory 1964  International cadre of Oxford-trained physicists Page 2

Oxford’s international standing  Global experimental leadership in:  Detectors  Tracker R&D  Construction & upgrade  Monte Carlo Simulation  Triggering / selection algorithms  Calibration  Exploitation / analysis 22nd June 2011 LHC Physics Stellar international reputation (Even before talking about accelerators & theory…) Page 3

Large Hadron Collider 22nd June 2011 LHC Physics 1 MJ melts 1.5 kg Cu Page 4

The accelerator… 1232 x 14.3 m dipoles Superconducting Superfluid Liquid Helium Cooled 22nd June 2011 LHC Physics Page 5

LHC Physics ATLAS Segment of 4π detector 22nd June 2011 Page 6

Semiconductor Tracker…  Robotic assembly of precision silicon tracker 2004  nd June 2011 LHC Physics Page 7

22nd June 2011 LHC Physics 8

The LHCb spectrometer  Vertex Locator (Silicon) RICH detectors Tracking Calorimeters 4Tm Dipole Muon System 22nd June 2011 LHC Physics Page 9

22nd June 2011 LHC Physics Page 10 RICH1 Front-end electronics Johan Fopma, Phil Sullivan & the electronics workshop team PIXEL anodes Level-0 board Kaptons

RICH1 Mechanics Mike Tacon & the workshop team Design and constructed the lower HPD mounting system Designed the upper system Designed the RICH gas enclosure

22nd June 2011 LHC Physics 2009: Cosmic rays Precision alignment Calibrations Data acquisition Combined tests Page 12

13 March 2010: first collisions 22nd June 2011 LHC Physics

First B + → J/  K + candidate 5 April 2010, 01:30:09 22nd June 2011 LHC Physics Page 14

22nd June 2011 LHC Physics Page  fb -1 Huge reach even then 2010  fb -1 Huge reach even then LAST WEEK

The Standard Model 22nd June 2011 LHC Physics Fields (Maxwell, Weak, Strong) Fermions (Dirac…) Masses & potentials. (Untested) Page 16

Sure things  Strong interaction  Weak interaction  Higgs Sector or other EWSB  Flavours 3 rd generation quarks (t and b)  CP violation 22nd June 2011 LHC Physics 45 physics publications from ATLAS on last year’s beam data Page 17

Strong interactions  Self-interacting force carriers  Perturbative regime  Jets of hadrons  Radiation from accelerated colour  Backgrounds to all other searches  Non-perturbative  Quark-gluon plasma  Nucleon structure 22nd June 2011 LHC Physics Page 18

muliti-TeV 22nd June 2011 LHC Physics Excited quarks Quantum Black Holes Contact interactions CM Energy = 4 TeV Page 19

Weak interactions  Masses and couplings well known  Self-interactions under study  Cross-sections diverge without new physics 22nd June 2011 LHC Physics ZZ WW Page 20

W charge asymmetry  Vector – Axial couplings (Chiral couplings)  Probe proton structure (Parton distributions)  Cancellation of systematic uncertainties 22nd June 2011 LHC Physics Page 21

Higgs sector – the model  Field couples to mass  Scalar potential  Vacuum expectation value  W, Z masses via Higgs/gauge interactions  Fermion masses via Higgs/Yukawa coupling  Field excitation = Higgs boson(s) 22nd June 2011 LHC Physics LHC sensitivity to almost all SM Higgs masses Page 22

Higgs boson production and decay  Coupling  mass  Production  Gluon fusion  Weak boson fusion  Decay  To heaviest allowed states 22nd June 2011 Page 23 LHC Physics

22nd June 2011 LHC Physics Last week: full ATLAS search Higgs analysis of 2010 data Page 24

22nd June 2011 LHC Physics Higgs search status Page 25

22nd June 2011 LHC Physics Page 26

3 rd Generation: t and b  Three generations needed for CP violation  Nearly decoupled from first two generations  Long lived b-quark hadrons  Standard Model: top Higgs coupling ~unity  Radiative corrections from top on m H  Role in electroweak symmetry breaking? 22nd June 2011 LHC Physics Page 27

22nd June 2011 LHC Physics Page 28

Using quantum corrections  For example:  Tree and penguin-level determinations of CKM angle   Charmless charged two-body B decays  B s mixing phase  s from B s → J/   Branching fraction of B s →      Angular distributions in B 0 → K*      B s →  and other radiative decays 22nd June 2011 LHC Physics Page 29 Over-constrain SM parameters Hunt for rare processes

Effect of Particle ID on  → K+ K   Early 900 GeV data  Hard-ish RICH cut on each kaon track DLL(K-pi)>15

Example of CP violation measurement  2010 data  Separate samples into B 0 and B 0 using particle ID  Raw asymmetries clearly visible in data: direct CP Violation > 3   Central values consistent with expectations and previous measurements  NB: corrections from production and detector asymmetry not yet corrected for

More speculative (perhaps?)…  Further generations  Unification of forces  Supersymmetry  WIMPs  Compositeness / substructure  New gauge forces / particles  Strong gravity  Extra dimensions  Something else? 22nd June 2011 LHC Physics Page 32

Supersymmetry  Partner particles  Spin differ by ½  Stabilise m H  Dark Matter candidates  “Missing” momentum  Huge reach at LHC 22nd June 2011 LHC Physics Page 33

Results 22nd June 2011 Page 34 LHC Physics 3 June Feb 2011 “Missing” momentum Scalar sum of momentum

Interpretation... 22nd June 2011 LHC Physics ATLAS 0 lepton CMS  T G. Ross et al 2010 data  approach cosmologically interesting region Page 35

LHC and ATLAS upgrade schedules LHC  Phase-0 Shutdown:  End 2012-mid 2013  Physics resumes 2014  Phase-I shutdown  End of 2017  Physics resumes end of of 2018  Phase-II  End of 2021 ATLAS  Phase-0  IBL installation  Repairs/consolidation  Phase-I shut down  Muon small wheels  Mini-FCAL  L1 calo topological trigger  Calorimeter readout  NewPix  Phase-II  Tracker  ready on surface end of 2020  TDAQ 22nd June 2011 LHC Physics Page 36

22nd June 2011 LHC Physics Unique Oxford capabilities Page 37 Existing tracker All Si-upgrade

Detector & Upgrade Grid Operations Computing Software 22nd June 2011 LHC Physics Page 38 Hardware

EXTRA SLIDES AJB 22nd June 2011 LHC Physics Page 39

Semiconductor Tracker close-up 22nd June 2011 LHC Physics Page 40

22nd June 2011 LHC Physics Page 41

42 CMS LHCb ATLAS ALICE Four Detectors inelastic 20 MHz crossing rate Record ~100 events/s 1 MB per event Micron-scale precision 22nd June 2011 LHC Physics

Higgs  diphoton 22nd June 2011 LHC Physics Page 43

December nd June 2011 LHC Physics Page 44

PDFs are determined in Deep Inelastic Scattering- STRONG Oxford involvement in HERAPDF- But can be used to predict cross sections for the LHC. Early LHC data, using 36pb -1, are well predicted using HERAPDFs ATLAS jets These data can also be input to the fit to reduce the uncertainties The CMS muon asymmetry data already reduces the uncertainties on the low-x u and d- valence PDFs These improvements allow us to predict Standard Model cross sections with greater certainty so that the signal/background for Beyond Standard Model physics is enhanced CMS μ asymmetry

Search for the ultra-rare decays B 0 s & B 0 d →  +  - The upper limits on the branching ratios are BR(B 0 s →  +  - ) < 5.6 x and BR(B 0 d →  +  - ) < 1.5 x at 95% confidence level. Standard model expectations BR(B 0 s →  +  - ) < 0.32 x and BR(B 0 d →  +  - ) < 0.01 x Approacing the world’s best measurement already with 2010 data

B 0 s → J/   (Early 2011 data) Important for measurement of weak mixing phase in B s system Amazingly small background