Download - Chris Parkes 1 LHC The Energy Frontier Chris Parkes, GridPP 8, April 2012 ATLAS CMS ALICE LHCb

Chris Parkes

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LHC The Energy Frontier

Chris Parkes, GridPP 8, April 2012

ATLASATLAS

CMSCMSALICEALICE

LHCbLHCb

• Direct Production

• Simpler to interpret

• Probes masses

< E

Two Routes to New Physics

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• Indirect Effects

• Model dependent interpretations

• Probes very high mass scales – virtual new particles

E=mc2

b

New particles

Contents: Selected new results• LHC Status

– 2011 data and 2012 expectation

• Heavy Ions (mainly ALICE)– Suppression/enhancement of particle rates

• Direct Production (mainly ATLAS/CMS)– The ‘H’ word– Electroweak / Top physics– SUSY

• Indirect effects (mainly LHCb)– Rare Decays– CP Violation - charm

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Sources:Moriond E’weak,LHCC

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LHC: The New Improved Energy Frontier


75 ns 50 ns

2011 – recap

Increase number of bunches

Increase number of bunches

Reduce beam size

from injectors

Reduce beam size

from injectors

Squeeze further

Squeeze further

Increase bunch

intensity

Increase bunch

intensity

Initialcommissioning

Initialcommissioning

Scr

ubbi

ngS

crub

bing

Mike Lamont, LHCC

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25 ns test

LHC Performance• LHC shows excellent performance• First two years of physics

• Recorded 40 pb-1 in 2010 at 7 TeV + Pb-Pb• Recorded 5 /1 fb-1 in 2011 at 7TeV + Pb-Pb

• 2012 – now restarted at 8 TeV

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Power of Grid:All collected data reconstructed and many results on full samples

Aims for year: ATLAS/CMS – need max luminosity

many interactions per bunch crossing>15 fb-1 (3x 2011)

LHCb – need seconds !small number interactions per bunch

> 1.5fb-1

ALICE – heavy ionsFirst proton – lead collisions

2012 LHC schedule Q1/Q2

First Collisions

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2012 LHC schedule Q3/Q4

Special runs

Special runs

Proton-lead

Proton-lead

Mike Lamont, LHCC

Followed by long shutdown to move to ~14 TeV8

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Heavy Metal FrontierLead Ions


Hadrons suppressed but photons shine !

Hadrons up to pT 100 GeV/c are suppressed

Photons up to ET 80 GeV are not

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LHC: The Energy FrontierDirect Production


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Higgs 1011) The last undiscovered particle in the Standard Model

– Higgs Mechanism gives masses to the W & Z

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Sta

ndar

d M

odel

Par

ticle

s

Higgs boson, spin=0

Electric charge 0

Higgs 1011) The last undiscovered particle in the Standard Model

– Higgs Mechanism gives masses to the W & Z

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Higgs boson

Mass = ?

2) The mass of the Higgs boson is not predicted

– The rate of production (cross-section) is predicted if you know the mass

Higgs 101

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3) The Higgs boson has lots of possible decay modes

– It prefers to decay to the heaviest thing available– Couples to mass

– But easier to find if low background rates– Best channel changes with Higgs mass

BR

Standard Model Higgs ?• Combination of many decay channels with FULL 2011 data sample

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1) Black solid line below 1: excluded. Observed number of events less than would

have if the Higgs had that mass16

Standard Model Higgs ?• Zoom in on interesting region

2) Black dashed line : expected if no Higgs Black solid > black dashed = hint of a Higgs signal

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Standard Model Higgs ?• Black line –

~probability of Higgs at that mass

• Sensitivity comes from ϒϒ channel

• ATLAS/CMS compatible

• New Tevatron result – also compatible

CMS Expected exclusion 114.5 - 543 GeVCMS Observed exclusion 127.5 - 600 GeV

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Narrowing in on the Higgs

• Black line – From Indirect Effects: top mass and (new) Tevatron W mass

• Yellow blocks – excluded by direct searches

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Indirect Effects: Prediction is from Electroweak results-W mass and top mass

Electroweak

LHC status 20

Cross-sections of Electroweak processes

W and Z Production• W/Z cross-section ratio

– sensitive test of SM at LHC

• W Charge Asymmetry – changes sign in LHCb region: constraints on the low x

quark content of the protons at high q2.

€

σW + −σ

W −

σW + +σ

W −

ATLAS/CMS

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Top Quark

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Top Quark

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Top quark spin correlations measured for 1st time

Top Quark

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Top quark mass approaching Tevatron

precision

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Supersymmetry (SUSY) 101

Propose new symmetry of nature: SupersymmetrySpin ½ Fermions (quarks, leptons) spin 0 boson superpartnerSpin 1 Bosons spin ½ fermion superpartner

SUSY not an exact symmetryMass of SUSY particles ≠Mass of normal particles

Since none discovered yet

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SUSY Motivation

4. SUSY provides a theoretical route to include gravity in “standard model”, and needed in string / M-theory

1/S

tren

gth

Log Energy GeV

1. SUSY allows unification of the forces 2. SUSY cancels divergences in SM

SUSY: theoretically beautiful and convenient – but is it true ?

3. Lightest SUSY particle (LSP) is candidate for dark matterMost models LSP is stable neutralino

SUSY + Exotics Searches SummarySUSY + Exotics Searches Summary

F. Cerutti - LNF-INFN 27

Optimal use of delivered data: Enlarge range of “experimental topologies”

look at as many “experimental topologies” as possibleThen make happy our friend theorists:

translate results in constraints to large variety of models

ATLAS – many analyses with FULL 2011 Luminosity

SUSY + Exotics Searches SummarySUSY + Exotics Searches Summary

F. Cerutti - LNF-INFN 28

Optimal use of delivered data: Enlarge range of “experimental topologies”

look at as many “experimental topologies” as possibleThen make happy our friend theorists:

translate results in constraints to large variety of models

Good Fraction of analyses updated with FULL 2011 Luminosity

SUSY is alive but she has a

headache

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InteractionPoint

Muon System

Calorimeters

Tracking System

Vertex Locator

RICH Detectors

Beyond The Energy FrontierIndirect Effects


• Very rare decay – enhanced rate by new physics– LHCb rate < 4.5 x 10–9 (95%CL), CMS rate < 7.7 x 10–9 (95%CL), ATLAS < 22 x 10–9 (95%CL)

• New physics SUSY models with large tan β ~ ruled out

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green – allowed regionsblack/red – exclusion limits from CMSyellow - exclusion region from LHCb Bs→μμ result

SM prediction 3.2 x 10–9 Rare Decays: Bsμ+μ-

N. Mahmoudi

Most rare decay ever seen !• B+ → π+μ+ μ–

– First observation

• 25±6 events

• 5.2 σ significance

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B0 → K*0μ+μ–

- Constraining new physics up to 10TeV

Beyond the Energy Frontier

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C P

CPParity InversionSpatialmirror

Charge InversionParticle-antiparticlemirror

Matter anti-matter (CP violation) 101

CP Violation Discoveries• Strange Quark System (Kaons)

– Discovery of CP Violation

• Beauty Quark systems (B)– CP violation theory in CKM matrix

– Also Bs, see next slide

• Charm System (D)– Is there CP Violation in Charm quarks ?– Predicted to be very small in SM– Good way of searching for New Physics ?

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6σ Asymmetry

Bs Matter Antimatter Asymmetry

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ArXiv:1202.6251v1, Feb 2012

B B

BsBs3.3σ

Asymmetry FIRST CP

CP Violation in Bs → J/ψϕ

• Powerful analysis to look for New Physics• Had been hints from TeVatron – but more precise LHC results give SM value

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1 fb-1, LHCb-CONF-2012-002

LHCb LHCc• LHCb was designed for b-quark studies

• But also ideal for studies of slightly shorter lived c quark, and 20 times more events

• CP Violation in charm sector (was) predicted to be very small in Standard Model < 0.1 %

• Bigger than this New Physics !

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cc

e.g.

CP Violation: Problem 1 – Initial Condition• Technical Scale Drawing of LHC Collision

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Proton (Matter)

Proton (Matter)

• Start with matter and no antimatter• Ending with more matter than antimatter is not a surprise

Take difference in CP Violation between two decays

CP Violation: Problem 2 – Detector

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• So if matter goes to a +ve particle and antimatter to –ve• Go to different parts of detector – can fake CP violation

1)Take difference in CP Violation between two decays

2)Reverse Magnetic Field Periodically

3)Choose a symmetric decay

+ve charge

-ve charge

• Particles bend in magnetic Field

Direct CP Violation in Charm

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€

ACP (K +K −) =Γ(D→K +K −) − Γ(D→K +K −)

Γ(D→K +K −) + Γ(D→K +K −)

€

ACP (π +π −) =Γ(D→π +π −) − Γ(D→π +π −)

Γ(D→π +π −) + Γ(D→π +π −)

€

ARAW ( f ) = ACP ( f ) + ADetector( f ) + AProduction

What we measure

What we want

What we don’t want (1)


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€

ACP (K +K −) =Γ(D→K +K −) − Γ(D→K +K −)

Γ(D→K +K −) + Γ(D→K +K −)

€

ACP (π +π −) =Γ(D→π +π −) − Γ(D→π +π −)

Γ(D→π +π −) + Γ(D→π +π −)

€


What we measure

What we want



Symmetric Final State


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€

ACP (K +K −) =Γ(D→K +K −) − Γ(D→K +K −)

Γ(D→K +K −) + Γ(D→K +K −)

€

ACP (π +π −) =Γ(D→π +π −) − Γ(D→π +π −)

Γ(D→π +π −) + Γ(D→π +π −)

€


What we measure

What we want



Symmetric Final StateMagnetic Field


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€

ΔACP = ACP (K +K −) − ACP (π +π −)

€


What we measure

What we want



Symmetric Final StateMagnetic Field

Take Difference of final states



• High Statistics– 1.4M K+K-, 0.4M π+π-

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€

ΔACPPhys. Rev. Lett. 108, 111602 (2012), 12th March 2012

€

ΔACP = −0.82 ± 0.21(stat.) ± 0.11(syst.) %


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€

ΔACP

€

ΔACP = −0.82 ± 0.21(stat.) ± 0.11(syst.) %

New Prelim Result, 28th February

€

ΔACP = −0.62 ± 0.21(stat.) ± 0.10(syst.) %

• Confirmation of Effect

• World Average 3.7 σ

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• First evidence of CP violation in charm sector

Interpretation: M. Gersabeck, S. Borghi, CP

http://arxiv.org/abs/1111.6515


€

ΔACP

Average: Marco Gersabeck

New Physics ?• CP Violation in charm sector (was) predicted

to be very small in Standard Model < 0.1 %

• We measure 0.82±0.24% (on difference)

• New Physics ?

• Well maybe not…

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• Pb – Pb collisions– Particle suppression / enhancement in new state of matter

• Higgs:– Tantalising hints of SM Higgs around 125 GeV

• We will know this year

• SUSY:– No signs of her yet in direct production or rare decays

• Rare Decays:– Most rare decay ever seen

• CP Violation:– First evidence for CP violation in charm sector

• Compatible with SM ?

2011 Summary

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• Pb – Pb collisions– Particle suppression / enhancement in new state of matter

• Higgs:– Tantalising hints of SM Higgs around 125 GeV

• We will know this year

• SUSY:– No signs of her yet in direct production or rare decays

• Rare Decays:– Most rare decay ever seen

• CP Violation:– First evidence for CP violation in charm sector

• Compatible with SM ?

2011 Summary

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2012New World record energy

Expect lots more data for Grid to reconstruct

New Physics ?

Download - Chris Parkes 1 LHC The Energy Frontier Chris Parkes, GridPP 8, April 2012 ATLAS CMS ALICE LHCb

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