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Claudia-Elisabeth  Wulz New Physics at the LHC Claudia-Elisabeth  Wulz New Physics at the LHC

Claudia-Elisabeth Wulz New Physics at the LHC - PowerPoint Presentation

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Claudia-Elisabeth Wulz New Physics at the LHC - PPT Presentation

CE Wulz Institute of High Energy Physics 1 Institute of High Energy Physics of the Austrian Academy of Sciences New Physics at the LHC Experimental environment 2 ID: 656221

energy physics institute lhc physics energy lhc institute high wulz susy trigger cms muon stop triggering qcd analysis vienna

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Slide1

Claudia-Elisabeth Wulz

New Physics at the LHC

C.-E. Wulz (Institute of High Energy Physics)

1

Institute of High Energy Physics of the Austrian Academy of Sciences

New Physics at the LHCSlide2

Experimental environment

2

C.-E. Wulz (Institute of High Energy Physics)

Students will work within the CMS Collaboration.

Almost 20 fb-1 of integrated luminosity of pp interactions are available (√s

up to 8

TeV

), 300 fb

-1

are expected by 2021 (√s up to 14 TeV). Experience of Vienna CMS group: triggering, tracking, reconstruction of tracks and vertices as well as of muons, b’s and t’s.One thesis showcase is mainly about triggering, the other about searches for new physics in the field of SUSY. Connections between triggering and physics are an important aspect for both.

New Physics at the LHCSlide3

Motivation for New Physics

3

The main motivation for the LHC, after the discovery of a Higgs boson, is the search for new physics.

The Standard Model, though extremely successful, leaves many questions open

.

It

needs to be embedded in an overarching theory, but which theory is it?

C.-E.

Wulz

(Institute of High Energy Physics) New Physics at the LHCConcrete predictions of experimental signatures for new physics exist for many models (SUSY, strong electroweak symmetry breaking, extra dimensions, etc.)Slide4

Scalar top quarks

4

C.-E.

Wulz

(Institute of High Energy Physics)

New Physics at the LHC

and are

expected to have large mixing, due to the large top Yukawa coupling.

The lower mass

eigenstate may be relatively light.Most analyses so far have exploited the decay channels or with as well as Slide5

Showcase 1 – Scalar tops decaying to charm

5

C.-E. Wulz (Institute of High Energy Physics)

Production of in association with two b-jets in the stop-

neutralino coannihilation region .

In this case the branching fraction is close to 100%.

Analysis strategies:

cut-based analysis

multivariate techniques as alternative background estimates from data where possible New Physics at the LHC

LO QCD

contributionLO electroweakcontribution

Signature: 2 b

-jets and missing energy, no leptonsBackgrounds:Slide6

Motivation for an Upgraded Trigger System

6

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHC

Example for improvement in triggering on scalar tops

(e.g. through better

transverse momentum

estimates or pileup subtraction)

The current trigger system has worked very well. It is designed for luminosities up to 10

34 cm-2s-1, average number of pileup events of about 25, and a maximal Level-1 output rate of 100 kHz. For the future, the physics potential of CMS must be maintained or extended, and aging hardware must not become an issue. Luminosity, centre-of-mass energy and pileup will increase. Slide7

Showcase 2 – Muon trigger upgrade

7

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHC

Analysis

-

like, flexible

trigger algorithms already at Level-

1 with new

FPGA’s:e.g. boosted decision tree pT assignmentmore muon candidates than now, with higher precision in p

T

muon isolation information b-tagging of jet candidates through use of muon information.

Currrent

muon

trigger in the CMS cavernSlide8

Synergies within the DK and connections

8

C.-E. Wulz (Institute of High Energy Physics)

Collaboration experiment – theoryA. Hoang (University of Vienna): QCD, SUSY

A. Rebhan (TU Vienna): QCD, SUSY

Theory groups (Institute of High Energy Physics): SUSY, QCD, new Dark Matter group (J.

Pradler

)

Development of trigger and reconstruction algorithms, data analysis in the fields of SUSY and other beyond the Standard Model physics

R. Frühwirth, M. Jeitler, J. Schieck (Institute of High Energy Physics)H. Abele (TU Vienna)ComputingAustrian Tier-2 GRID centreInternational CollaborationsCERN and institutions worldwide

New Physics at the LHCSlide9

Thank you for your attention!

9

C.-E.

Wulz

(Institute of High Energy Physics)

New Physics at the LHCSlide10

BACKUP

10

C.-E.

Wulz

(Institute of High Energy Physics)

New Physics at the LHCSlide11

Added value

SUSY at the LHC

SUSY at the LHC

Students will work in a stimulating environment:

investigation of fundamental physics problems

world’s most powerful particle accelerator

large scientific community but human-sized research groups

international, multidisciplinary

Focus on research activities will shift to physics analyses, after long and important development work in triggering and tracking

Reinforcement of collaboration between theorists and experimentalists

C.-E.

Wulz

(Institute of High Energy Physics)

11

New Physics at the LHCSlide12

SUSY limits from CMS

12

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHCSlide13

ATLAS direct stop limits

13

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHCSlide14

ATLAS direct stop limits in 0-lepton channel

14

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHC

ATLAS-CONF-2013-024Slide15

Stop to charm

15

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHC

Alternative signature:

monojet

if Slide16

Projections for stop

16

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHCSlide17

CMS Trigger upgrade

17

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHCSlide18

Tail clipping

18

C.-E. Wulz (Institute of High Energy Physics)

New Physics at the LHC

The initial pT estimate of about 32 GeV is too large

for the input

D

f

(ME1-ME2) value (50

f-units) according to the 5% tail fraction curve(shown in black). The initial 32 GeV estimate is substituted by the highest pT for which50 f-units is below the 5% tail fraction curve, in this case 12 GeV.