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Particle Physics Open Day

December 9 2019

(WELCOME!)

The Oxford Particle Physics

Program

Farrukh Azfar

Director of Graduate Studies for

Particle Physics(thanks Prof. Daniela Bortoletto& PP colleagues)

Higgs as a new tool for

discovery

Identify the new

physics of dark

matter

Oxford is addressing the science drivers of particle physics

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The physics of

Neutrino mass

Understanding

cosmic

acceleration

Explore the

unknown: new

particles and

new interactions

Outline

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• Why search for new physics ?

• Particle Physics Groups at Oxford

• ATLAS (Higgs, SUSY, Exotics, PDFs, Detectors, SM)

• LHC-b (CP Violation, Rare Decays, Detectors and more)

• Neutrinos (CP violation, Accelerator, Search for Majorana nus)

• LZ (Dark Matter)

• Mu3e (Lepton flavour violation)

• LSST (Dark Energy)

• Detector based projects

• Talk to us today – come and find us – examine opportunities!!

• For a list of projects look here (these get updated too)

http://www2.physics.ox.ac.uk/study-here/postgraduates/particle-

physics/thesis-topics

The Standard Model

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The Standard Model

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• 1964 SM Theory

• 1984 LHC Design

• 1996 Start LHC construction

• 2009: first collisions

• 2012: Higgs Discovery

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

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The Higgs boson• The discovery of the Higgs Boson raises many questions

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The Higgs boson• The discovery of the Higgs Boson raises many questions

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27km

Circumference

ATLAS

LHCb

The Large Hadron Collider – A Discovery Machine

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Operates above energy scale of SM:

13 TeV in 2015

Probes new physics

ATLAS

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Barr, Bortoletto, Cooper–Sarkar, Gwenlan, Hays,

Huffman, Nickerson, Shipsey, Viehhauser,

Weidberg

The Oxford ATLAS Group• Our goals:

– Shed light on new Higgs boson

• Measure its properties

• Improve our understanding of SM

– Discover new physics beyond SM

• Can we make & discover Dark Matter?

• Are there heavier Higgs bosons?

• Is nature supersymmetric?

• Look for more Exotics signatures

– Build key parts of next generation LHC

detector11

Oxford Higgs Group• 3 academics: Bortoletto, Hays, Shipsey

• 2 Postdocs: Schopf (H→bb) and Artoni

(H→ZZ, H→𝜇𝜇 )

• 9 students: Ambroz, Foti, Karava, Miranova ,

Tosciri, Smith, Windischhofer Wolker, Zgubic

• Measured the Higgs coupling to b-quarks!

• More data will allow us to:

– Probe the Higgs coupling to the second

generation

– Test for physics beyond the SM (using for

example Effective Theory Interpretation)

– Search for new scalar particles

• Advanced analysis techniques (neural networks)

and major contributions to physics objects

• Strong collaborations with theorists

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Higgs in run 2 of the LHC• Oxford recent highlight contributions

• H→bb observed(expected) significance: 5.4(5.5)  

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Higgs in run 2 of the LHC

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Until 6 years ago the

Yukawa coupling was

essentially a conjecture

no such term had ever

been seen in nature

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“SM & beyond” group• SM, Supersymmetry, Dark Matter,…

– 2 Academics: Barr, Gwenlan

– 2 Postdocs: Merlassino (3rd Gen SUSY and

triggers) and Nagai (Tracker ops and Strong

SUSY)

– 6 DPhil Students: Gallardo, O’Neill, Pownall,

Wuerzinger, Harris, Conroy

• Oxford students lead small teams & have many

world-first searches @LHC

– PDFs, W+jets, Squarks, Gluinos, Sleptons,

Higgsinos, Dark Matter, …

• Also contribute to ATLAS experiment

– e.g. triggering on events with Dark Matter

– reconstructing missing momentum

• Possible to combine with theory studies

Supersymmetry

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• New symmetry of

space and time

(extends rotations

and boosts)

• Links fermions and

bosons

• Provides

“superpartner” to

each SM particle

• Lightest partner

Dark Matter

• Path to unification

& string theory

Dark

matter

Supersymmetry example: Gluinos• Gluinos: spin-1/2 partners of gluons

• Masses expected ~ few TeV

• Produced in pairs & frequently

• Decay to (lots of) quarks + Dark Matter

(missing momentum)

1716 jet + missing momentum candidate

Aaron (DPhil student)leading the analysis

SM example: Proton Structure (PDFs)

• PDFs uncertainties feed into ~all LHC

analyses, limiting measurements of Higgs

properties, reach of BSM searches, etc.

• LHC measurements provide strong

constraints on quark and gluon content

• Oxford Group lead the ATLAS analyses

using LHC data to determine PDFs

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Gavin (DPhil student) leading current analyses

A.Cooper-Sarkar,

academic (retired)

Gavin & Eimear (DPhil students) also leading final Run 2 W+jetsmeasurement

BLUE

includes

ATLAS

W+jets

Oxford Higgs (SM) Exotics Group

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• Academic : Huffman

• 2 Fellows: Beresford, Frost

• Post-doc: Balunas

• 6 Students: Celli, Grundy, Paredes,

Stanislaus, Stankaityte, Veliscek

Search for new particles and effects

- Jet final states with b-quark pairs

- Higgs pairs decaying to b quark pairs

Novel techniques : Higgs tagging, NN

Extensive collaboration with theorists

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Instrumentation: Oxford Physics

Microstructure Detector Laboratory (OPMD)

• State-of-the art facility enhancing the development of new radiation sensors in Oxford and the UK

• Development of novel detectors for particle physics, photon science, and astrophysics

• Currently focusing on

– Depleted Monolithic Pixel Detectors for ATLAS

– Ultra Fast Silicon Detectors

– CCD for LSST Sharma

ShipseyBortoletto

Placket

Metodiev

Wood Weatherill

Mironova

Barrel Silicon Tracker for ATLAS Upgrade ITk

• Use unique combination of facilities in Oxford

– Mechanical workshop, CNC & CMM etc.

– Autoclave (carbon fibre sandwich structures)

– Photofabrication

• Assembly of carbon fibre staves for ITk

• Design and testing of high speed electrical tapes

• Detector integration at CERN

• Engineering for barrel strip detector

Wastie

Viehhause

r

Nickerson

Weidberg Jones

Yang

Li

(grad student)

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

23ATLAS CONTROL ROOM START OF RUN 2

LHCb

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• try

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The LHCb experiment

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• 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

• LHCb is a general purpose experiment for

examining the “forward region” of the proton-proton

collisions

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CP violation!

CP-violation in beauty hadrons

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In beauty system, the SM predicts sizable CP-violation.

And this is what we see!

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 !

B0→K+π-

B0bar→K-π+Signal + residual

background

• 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 — one of the key ingredients of a precise ρ,η determination!

• Oxford driven analysis has measured =74+5 -6 deg using B±→D0K± this

already equals the precision of previous measurements. Aiming to reduce

error to ± 3 deg

Precise CKM measurements

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 Academics + 1 RSF (Harnew, Wilkinson, John, Malde)

• 10 D.Phil (Bijorn, Gruberg Cazon, Murphy, Pili. Pullen, Rollings Fischer,

Scantlebury-Smead , Mohammed, Smallwood, Suljk)

The physics of neutrinos• T2K

• HyperK

• PROTODUNE

• DUNE

• SNO+

• MICROBooNE

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T2K Neutrino Oscillation experiment

• Measure disappearance of muon neutrinos to determine θ23 and Δm2

• Measure electron neutrino appearance

• Determine if neutrinos and antineutrinos behave the same. In fact, there is a

chance to find CP violation in THIS experiment.

• The group is also studying future neutrino experiments for CP violation discovery.

T2K results so far

T2K results so far

CP conserving values outside of 2σ region

for both hierarchies

Upgrade SK to Hyper-K Start ~2022Total water mass of 0.99 Mt

Future = Liquid Argon in USA and Water Cherenkov in Japan

DUNE: planned long baseline

experiment. Start ~2022

4x10kT

PROTODUNE

• 770 t LAr mass

• Exposed to H2 (DP)

and H4 (SP) test

beams at CERN (𝑒, K, 𝜇, 𝑝, 𝜋)

• Prototyping

production and

installation

• Validating the design

and long-term

operational stability

• Understanding,

calibration, dE/dx,

PID etc.

• PROTODUNE SP

2018 data taking

Daniela Bortoletto, LISHEP 2018,

Salvador36

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The Dark Universe

LZ

LSST

• 7-tonne two-phase Xenon TPC (5.6t fiducial) to search for xenon

nuclei recoiling in response to collisions with dark matter particles.

• Oxford provides crucial TPC sensors/readout and simulations tools.

• Full exploitation requires significant simulation and analysis effort.

• Oxford group focused on analysis/simulation tasks.

Dark Matter Search with LZ (LUX-ZEPLIN)

Oxford team:Hans Kraus

Amy Cottle

Andrew Stevens

Eilish Gibson

Matthew Tan

Niamh Fearon

Aiham Al Musalhi

LZ at the Sanford Underground Research Facility

Completion of installation and Commissioning in early 2020.

Plenty of D.Phil. opportunities with analysis of early data!

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Exploring the nature of dark energy

Oxford LSST Camera Test Stand

Particle Astro Synergy

PP: Azfar/Tseng/ShipseyAstro:Davies/Dunkley/Fender/Ferriera/Jarvis/Lintott/ Miller

Dark Energy LSST Meeting Oxford July, 2016

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Mu3e• Features

– Charged lepton flavor violating

– Via neutrino mixing

– Suppressed by (𝛥m𝜈2/ mW

2)2

– Expected BR(μ+→e+e-e+) < 10-50

• Importance

– Observable BR only from New

Physics

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Welcome to Oxford Particle Physics