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The Oxford Particle Physics Program The Oxford Particle Physics Program D. Bortoletto 30.11.2016 Graduate Opportunities 1 Oxford is addressing the science drivers of particle physics Higgs as a new tool for Identify the new discovery physics of dark matter The physics of Explore the unknown: new particles and new interactions Understanding cosmic Neutrino mass acceleration 2 Outline • Particle Physics Groups @ Oxford addresses these drivers through: – ATLAS Experiment – LHCb Experiment – Neutrino Experiments – Dark Matter Searches – Many detector based projects – For full list, look here: http://www2.physics.ox.ac.uk/study- here/postgraduates/particle-physics/thesis-topics 3 The Standard Model • 1964 SM Theory • 1984 LHC Design • 1996 Start LHC construction • 2009: first collisions 2013 4 Why look beyond the Standard Model? § Experimental Evidence § Non-baryonic dark matter (~23%) § Inferred from gravitational effects § Rotational speed of galaxies § Orbital velocities of galaxies in clusters § Gravitational lensing § ….. § Dark Energy (~73%) § Accelerated Expansion of the Universe § Neutrinos have mass and mix § Baryon asymmetry § ….. 5 Why look beyond the Standard Model? § Experimental Evidence § Non-baryonic dark matter (~23%) § Inferred from gravitational effects § Rotational speed of galaxies § Orbital velocities of galaxies in clusters § Gravitational lensing § ….. § Dark Energy (~73%) § Accelerated Expansion of the Universe § Neutrinos have mass and mix § Baryon asymmetry § ….. 6 Why look beyond the Standard Model? § Aesthetic/Theoretical Reasons § Hierarchy problem § Gravity is not included § No neutrino mass or mixing § Why 3 families? § .... § …. § …. 7 The Higgs boson • ATLAS and CMS discovered a Higgs-like boson 2012 • ONLY spin 0 elementary particle • Couplings are NOT dictated by gauge symmetry – Why do they take the values that they take? • SMall Higgs boson Mass must be protected by – New symMetry (Maybe SUSY) – Not eleMentary particle (Exotic Physics) • Symmetry breaking – What is the underlying reason? Higgs boson raises many more questions Why this shape? 8 If the next scale is the Plank scale 19 Ep= 1.2 x 10 GeV 13/12/2016 D. Bortoletto, Nottingham 9 SUSY • SUSY postulates “superpartners” to each SM particles • Higgs sector extended to 5 Higgs 10 SUSY • Why? Naturalness of Higgs Mass Unification Dark matter 11 The Large Hadron Collider Big (27km circumference) to explore distances of 1.5 x 10-20 m Cold (1.9K) reaching the highest energies (now at 13 TeV, T=1.15 x 1017 K) Recreating conditions when universe was a billionth of a second old … 27 km≈ 16 miles An unprecedented accelerator: 1232 superconducting dipole magnets operating at 8.3 T ©© CERN CERN field 12 Barr, Bortoletto, Cooper–Sarkar Gwenlan, Hays, ATLAS Huffman, Issever, Nickerson, Shipsey, Viehhauser, Weidberg 13 The Oxford ATLAS Group • Our goals: – Shed light on the Higgs boson • Measure its properties • Improve our understanding of SM – Discover new physics beyond SM • Are there heavier Higgs bosons? • What is dark matter ? Does it couple to the Higgs? • Is nature supersymmetric? • Look for more Exotics signatures – Build key parts of next generation LHC detector 14 LHC at 13 TeV • try Ratio of cross sections at 13TeV/8TeV 15 Higgs in run 1 of the LHC PRD 92, 012006 (2015), arxiv: 1412.2641 JHEP 04 (2015) 117, arxiv:1501.04943 • The Higgs coupling are proportional to mass • Oxford main contributions – H→WW ➞ the most precise measurement of any Higgs decay channel at the LHC – H→ττ ➞ the first evidence of Higgs decay to leptons David’s (winner of the Springer thesis award) H→WW , Jacob H→ττ 16 Higgs in run 2 • Oxford goals is to look for new physics in precision Higgs measurements: – H→WW in gluon fusion and vector boson fusion production • pT differential Higgs cross section in H→WW which is sensitive to new physics – Off-shell measurements in H→ZZ →2l2ν : • Measure the Higgs width (Luigi M) • Search for higher mass Higgs (Mariyan) • Invisible Higgs decays HZ→2l+inv probing dark matter (Luigi V) – H →bb • Largest decay mode, but very poor S/B mbb – H →µµ • Very rare decay in the SM, probes Yukawa-coupling to 2nd generation 17 Search SupersyMMetry in run 2 with multijets • First search for SUSY with the 13 TeV data arXiv:1602.06194 RUN 2 RUN 1 • LHC @ 13 TeV critical to extend searches for SUSY 18 Beyond the SM with Higgs pairs (→4b or 2W2b) Oxford Exotics Group ATLAS-CONF-2016-035 Phys.Rev. D94 (2016) no.5, 052002 Important for Higgs self-coupling : Eur.Phys.J. C76 (2016) no.7, 386 ; arXiv:1606.09408 Improve jet mass • Calibration NEW • New algorithms & ideas Novel b-tagging algorithms • Variable R track jets • B-tagging without tracks J.Phys. G43 (2016) no.8, 085001 ATL-PHYS-PUB-2016-013 19 Instrumentation: Oxford Physics Microstructure Detector Laboratory (OPMD) • A state-of-the art facility enhancing the development of new radiation sensors in Oxford and the UK that will: – Strengthen UK role in construction of large Particle Physics Detectors for the Large Hadron Collider and other future international facilities enabling the discovery of new phenomena in the Universe – Allow the development of novel silicon sensors that can be used not only for particle physics but also in astrophysics, photon science (for example Diamond) and other areas of applied science – Train the next generation of young physicists in the development of new instruments and tools for applications in fundamental physics research and technological spin-offs. Daniela Bortoletto and Ian Shipsey Only a few exaMples shown….. – More information at http://www2.physics.ox.ac.uk/research/atlas – Physics Groups • Standard Model Group • Higgs Group • SUSY Group • Exotics Group – Hardware Groups • Strip tracker upgrade mechanics • HL-LHC R&D on Optoelectronics • New HV CMOS detectors (new Laboratory for detector development) – Computing Groups • ATLAS Metadata and Databases • … 21 What to expect as a Student in ATLAS • Students work in small friendly teams • Have a big impact • Gain high visibility in ATLAS • Take responsibility for projects or detectors • Long term stay at CERN • Shifts at the detector ATLAS COTROL ROOM START OF RUN 2 22 What to expect as a Student in ATLAS • Students work in small friendly teams • Have a big impact • Gain high visibility in ATLAS • Take responsibility for projects or detectors • Long term stay at CERN • Shifts at the detector ATLAS COTROL ROOM START OF RUN 2 23 The Oxford ATLAS Group • An important ingredient of our success in Run1 and now in Run 2 of the LHC OUR STUDENTS! • Broad range of expertise in many areas in group • We are very well plugged into ATLAS • Enthusiastic and supportive work environMent 24 SoMe StateMents froM our Students…. • “…. which makes our work cutting edge as well as extremely exciting for all of us involved.” • “….but never before have studies been done using the actual detector output so this again is another first which I feel very lucky to be involved in.” • “I think what I enjoy the most about the DPhil at Oxford is the interesting mix of experimental and theoretical physics.“ • “It is satisfying to produce results which are both of interest and use to the experiment. “ 25 LHCB • try 26 The LHCb experiMent • LHCb is a general purpose experiment for examining the “forward region” of the proton-proton collisions • Several trillion B hadrons have so far been produced at LHCb. – to make precision measurements of CP violation – to search for New Physics in rare B decays • Critical for allowing this physics are particle identification and excellent vertex reconstruction. – The RICH detectors were designed and build in Oxford – VELO is a major Oxford activity 27 CP violation! 28 CP-violation in beauty hadrons In beauty system, the SM predicts sizable CP-violation. And this is what we see! B0→K+π- 0 -π+ Signal + B bar→K residual background Rate of decay and CP-conjugated process are clearly different ! Often, the SM predictions are precise. The goal then is to make Correspondingly precise measurements. Any Inconsistencies would indicate New Physics at work ! 29 Hunting for SUSY with Bs→μμ Very rare, and very well predicted in In SM In SUSY Standard Model (BR ~ 3 x 10-9 !) But in supersymmetry (SUSY) significant enhancements can occur ! 30 Precise CKM measurements • The apex of the CKM triangle is the world average measurement of their value (from pre-LHC measurements of the triangle’s sides and angles). • Large error on γ — one of the key ingredients of a precise ρ,η determination! • Oxford driven analysis has measured γ =71 ± 16 deg using B±→D0K± this already equals the precision of previous measurements. Aiming to reduce error to ± 4 deg LHCb offers fantastic opportunities for graduate students • All graduate students are working on high-profile analyses of LHC data. • Graduate students participate fully in the running of the experiment at CERN. • BELOW: 3rd yr D.Phil. in the LHCb control room • The Oxford LHCb Oxford enjoys an great position in the international collaboration. • 3 faculty, 5 research staff, 12 D.Phil. So there can be CP violation in the neutrino sector 33 The physics of neutrinos • T2K • HyperK • MicroBooNE • SBND • DUNE • SNO+ 34 T2K Neutrino Oscillation experiMent Start with muon neutrino beam in Tokai 50 Kt Look for electron neutrino appearance in Kamioka 2 • Measure disappearance of muon neutrinos to determine θ23 and Δm • Have found electron neutrino appearance • Do neutrinos and antineutrinos behave the same? • Measure as accurately as possible – a chance to find CP violation in THIS experiment. • The group is also studying
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