KET-BSM meeting Aachen, April 2006

KET-BSM meeting Aachen, April 2006KET-BSM meeting Aachen, April 2006

View from the Schauinsland in Freiburg a couple of weeks agoView from the Schauinsland in Freiburg a couple of weeks ago

Sascha Caron

University of Freiburg

How does nature behave at How does nature behave at 1TeV ?1TeV ?

A search strategy for SUSY et al. A search strategy for SUSY et al.

Outline: 1Outline: 1stst Motivation, 2 Motivation, 2ndnd Strategy, 3 Strategy, 3rdrd Questions Questions

The situation in 2006The situation in 2006

• We still don’t know the origin of EW symmetry breaking We still don’t know the origin of EW symmetry breaking The Higgs boson is not discovered yetThe Higgs boson is not discovered yet

• Even with the SM Higgs: Even with the SM Higgs: ‘‘fine tuning’ is required in the model to remain valid to high energies?,fine tuning’ is required in the model to remain valid to high energies?, Gravity is not included?, Fermion masses? What is Dark Matter?,…Gravity is not included?, Fermion masses? What is Dark Matter?,…

typical solutions by increasing the number oftypical solutions by increasing the number of symmetries, dimensions, forces, …symmetries, dimensions, forces, …

Higgs ? Something else?Higgs ? Something else?

Sascha Caron page 1Sascha Caron page 1

Investigate if there is Investigate if there is other physics beyond the other physics beyond the Standard ModelStandard Model

Investigate if there is Investigate if there is other physics beyond the other physics beyond the Standard ModelStandard Model

Investigate if EW Investigate if EW symmetry breaking symmetry breaking is caused by a Higgs.is caused by a Higgs.

Investigate if EW Investigate if EW symmetry breaking symmetry breaking is caused by a Higgs.is caused by a Higgs.

Part 1Part 1Higgs working groupsHiggs working groupsat ATLAS and CMSat ATLAS and CMS

Part 1Part 1Higgs working groupsHiggs working groupsat ATLAS and CMSat ATLAS and CMS

Part 2Part 2This approach:This approach:

Data mining strategies Data mining strategies How to find anything potentially How to find anything potentially

interesting and previously interesting and previously unexpected in the data?unexpected in the data?

Part 2Part 2This approach:This approach:

Data mining strategies Data mining strategies How to find anything potentially How to find anything potentially

interesting and previously interesting and previously unexpected in the data?unexpected in the data?




Sascha Caron page 2bSascha Caron page 2b

Number of Higgs doubletsNumber of Higgs doublets

Nu

mb

er

of m

od

els

Nu

mb

er

of m

od

els

303055

Worried about Worried about your search strategy?your search strategy?

hep-th 0411129 SUSY spectra from special string vacuahep-th 0411129 SUSY spectra from special string vacua

What do we expect to find at the LHC?What do we expect to find at the LHC?


One physicist's schematic view of particle physics in the 21st centuryOne physicist's schematic view of particle physics in the 21st century (Courtesy of Hitoshi Murayama)(Courtesy of Hitoshi Murayama)Sascha Caron page 3Sascha Caron page 3

MSSM

CMSSM

SUSY VERSIONSOF THE SM NMSSM

(an additional Higgssinglet)

MN2SSM

SUSY with extra DimSUSY with extra forcesSUSY+ little Higgs,…


Choose this point,Choose this point,look at the LHC data,look at the LHC data,

exclude or not!exclude or not!


We found no deviation We have excluded this point/area which

is epsilon of the parameter space

We found a deviation

Does this mean that the ‘real’ modelis this parameter point?

Is it efficient to work like this?Is it efficient to work like this?

Examples:Examples:General Search for new Phenomena at H1 (2004) andGeneral Search for new Phenomena at H1 (2004) andD0 Sleuth approach (2002 but only top final states)D0 Sleuth approach (2002 but only top final states)

Finding the unexpected – explaining the originFinding the unexpected – explaining the origin

The other strategy: START FROM THE DATAThe other strategy: START FROM THE DATA

1)1) Search for deviations in (almost )Search for deviations in (almost )allall final states final states(they are all interesting either as signal or to understand background)(they are all interesting either as signal or to understand background)

2)2) Determine ‘deviation(s)’ or ‘inconsistencies’ (e.g. all muon finalDetermine ‘deviation(s)’ or ‘inconsistencies’ (e.g. all muon final states have problems)states have problems)3) Determine their origin (detector effect, Monte Carlo? , new physics?)3) Determine their origin (detector effect, Monte Carlo? , new physics?)

4)4) Re-determine expectation and Re-determine expectation and repeat step 1-4) until publication in journal repeat step 1-4) until publication in journal


• Event yields for HERA 1 data

First time a HEP experimentanalyzed all final states

Example: H1 General SearchExample: H1 General Search


Channels which have Channels which have not been syst. studied beforenot been syst. studied before

We investigatedall Mall and ΣPT

distributions


We developed We developed a a simple and simple and

powerfulpowerful algorithm algorithmto to find and find and quantifyquantify

deviations deviations automaticallyautomatically

Is this approach sensitive to New Physics?


H1 tested various models and found compatible sensitivity H1 tested various models and found compatible sensitivity to direct searches in all of them (without tuning a cut)!to direct searches in all of them (without tuning a cut)!

Next step for me: Sensitivity tests of such an approach forNext step for me: Sensitivity tests of such an approach forCMSSM points at ATLAS CMSSM points at ATLAS

Martin Wessels Ph.D. thesis RWTH AachenMartin Wessels Ph.D. thesis RWTH Aachen

MC

SM

exp

erim

ents

with

larg

er d

evia

tion

MC

SM

exp

erim

ents

with

larg

er d

evia

tion

1010

100000100000

10001000

Is this possible at LHC? Is this possible at LHC?

Is this the best strategy for an Is this the best strategy for an

‘ ‘early discovery’?early discovery’?

What do we need for this search?What do we need for this search?

What can we learn from theory?What can we learn from theory?

Is this possible at LHC ? Is this possible at LHC ?

Yes ! (H1 has made the Yes ! (H1 has made the ‘proof of principle’)‘proof of principle’)


Is this the best strategy for Is this the best strategy for

‘ ‘early discovery’?early discovery’?

Answer 1 : DEPENDS ON THE PHYSICSAnswer 1 : DEPENDS ON THE PHYSICS

Answer 2 :Answer 2 : I’M NOT 100% SURE TO BE HONESTI’M NOT 100% SURE TO BE HONEST

We like to start from a ‘simpler’ scenario and to extend We like to start from a ‘simpler’ scenario and to extend (after we know some of the detector response and of physics at 1 TeV)(after we know some of the detector response and of physics at 1 TeV)

Our attemptOur attempt : :

Start from channels where one might expect something new Start from channels where one might expect something new and you don’t know exactly what and where you can and you don’t know exactly what and where you can predict some of the background from data predict some of the background from data

pT_miss channelspT_miss channels (Dark Matter…?) (Dark Matter…?)

Idea: Idea: ““less model dependent” SUSY/DM searchesless model dependent” SUSY/DM searches

What do we need for this?What do we need for this?

SM prediction (with complete uncertainty) in (finally) all channelsSM prediction (with complete uncertainty) in (finally) all channels (Multi purpose event generators)(Multi purpose event generators)

A multi-purpose analysis framework (as in H1)A multi-purpose analysis framework (as in H1) (I thought it would (I thought it would be nice to run a simple version of this even on-line)be nice to run a simple version of this even on-line)

Uncertainties and fudge factors from dataUncertainties and fudge factors from data (calibration with data candles, use data without pt_miss, use fits to (calibration with data candles, use data without pt_miss, use fits to fudge factors, use a global background determination strategy, make fudge factors, use a global background determination strategy, make ‘fake data’ for each channel, use fast ways to go from 1-4)‘fake data’ for each channel, use fast ways to go from 1-4)

Later: A way to learn what we have foundLater: A way to learn what we have found


What can What can

we learn we learn

from theory?from theory?

- - What are ‘model independent’ the best variables to determine the What are ‘model independent’ the best variables to determine the underlying physics (Et, mass, endpoints?, spin information, something underlying physics (Et, mass, endpoints?, spin information, something else?)else?)

- What do you need to determine the nature@1TeV Lagrangian? Do you - What do you need to determine the nature@1TeV Lagrangian? Do you know already how to do this?know already how to do this?Would it be helpful to publish a ‘pseudo’ ATLAS/CMS signal?Would it be helpful to publish a ‘pseudo’ ATLAS/CMS signal?

- Tune QCD radiation: Best MC tunes via fits to almost all published dataTune QCD radiation: Best MC tunes via fits to almost all published data

- How can we best use Jet+X events to determine Jet+Ptmiss+Y events? How can we best use Jet+X events to determine Jet+Ptmiss+Y events? (e.g. include fit procedure into Generators to determine some QCD (e.g. include fit procedure into Generators to determine some QCD radiation weight factors instead of predicting e.g. W+jets events with radiation weight factors instead of predicting e.g. W+jets events with Z+jet events?)Z+jet events?)

What can What can

we learn we learn

from theory?from theory?

Attempts to determine LHC signals:Attempts to determine LHC signals:- LHC olympics (a signal only ‘fun’ analysis)- LHC olympics (a signal only ‘fun’ analysis)- LHC inverse problemLHC inverse problem- BARD (automizing ME calculations of Madgraph and fitting to BARD (automizing ME calculations of Madgraph and fitting to signals)signals)Any interest from german theory to start something better? Any interest from german theory to start something better?

Determine a general LHC Standard Model:Determine a general LHC Standard Model:Madgraph/event, Sherpa/Amegic, …. Madgraph/event, Sherpa/Amegic, ….

General BSM Model Generators to determine the efficiency of General BSM Model Generators to determine the efficiency of such an approach for any model such an approach for any model (can we be more general?)(can we be more general?)

A General analysis of LHC dataA General analysis of LHC data

Theory and ‘Going the way into the other direction’…Theory and ‘Going the way into the other direction’…

SummarySummary

I’ve tried to illustrate I’ve tried to illustrate what we like to dowhat we like to do

and why and why (build such a framework for ATLAS)(build such a framework for ATLAS)

Somebody interested in joining a generalSomebody interested in joining a generaldata analysis strategy in germany ?data analysis strategy in germany ?

The SUSY search strategy

Examples of SUSY searches at LHC:jjjjv channel cuts optimized on specific CMSSM points

• 1 jet with pT >100 GeV, 4 jets (pT>50 GeV) • ET

MISS > max(100 GeV ,0.2Meff)• Transverse sfericity ST>0.2• No isolated muon or electron (pT>20 GeV)• better signal to background with a extra lepton• + scanning on E_T distributions

I think we can gain sensitivity by exploring more channels (or by subdividing the data instead of cutting)

Does the true signal slip through our harsh cuts?

A bit more motivationA bit more motivation

Sascha Caron page ?Sascha Caron page ?

A significant danger is finding correlations and signalsA significant danger is finding correlations and signals that do not really exist. that do not really exist.

Many examples in particle physics historyMany examples in particle physics history

We are looking for deviations …We are looking for deviations …How surprised should we be to find some?How surprised should we be to find some?

How likely is a 4-5 sigma deviation at LHCHow likely is a 4-5 sigma deviation at LHCeven if there is nothing in the data?even if there is nothing in the data?

Sascha Caron page 20Sascha Caron page 20 Unsolvable problem if you use 2000 PhD studentsUnsolvable problem if you use 2000 PhD students

Step 1: Repeat the whole analysis with a pseudo data experiment(dice your own MC data) many times.

Quantify the deviationsQuantify the deviations

3%3%


Step 2: Count how manytimes you find deviations bigger than in those in your real data.

3%3% of the of the ““Pseudo H1 experiments”Pseudo H1 experiments”

have found have found a bigger deviation a bigger deviation

Num

ber

of c

hann

els

Num

ber

of c

hann

els

1 101 10-1-1 10 10-2-2 ProbabilityProbabilityto find to find

deviation indeviation inthis channelthis channel

I know that this is not a new idea, but we do not often use itI know that this is not a new idea, but we do not often use it

What are the numbers for ATLAS or CMS?What are the numbers for ATLAS or CMS?

KET-BSM meeting Aachen, April 2006

Documents

Transcript of KET-BSM meeting Aachen, April 2006