MSSM A/H →

Paper published with first Run 2 data (3.2 fb^-1) The result improves previous searches for the mass range m_A > 500 GeV

Later analysis were done for ICHEP’16 (13.3 fb^-1) and 2015+2016 luminosity (36.1 fb^-1)

Conclusions

- This thesis was performed during the Runs 1 and 2 of the LHC, and the Long Shutdown, both in physics analyses and technical tasks of the Tile Calorimeter of the ATLAS detector

- The work of this thesis has contributed to obtain strong evidence of the direct coupling of the Higgs boson to fermions, a result which is fully compatible with the Standard Model

- In addition, it has contributed to expand the non-allowed space of

parameters of one extension beyond the Standard Model, the MSSM, and to prepare the field to the upcoming data of Run 2

Thank you for your attention!

Backup

Enhancement of the Pulse Simulator

Simulation of high pile-up conditions

Old version: one out-of-time pulse

New version: seven out-of-time pulses (bunch-space configurable)

- Previous version, only one out-of-time pulse was allowed

- Improvement: added one additional pulse per bunch-crossing

Extended pulse shape

Pulse shape Blue → old version Red→ full available

New version: pulses with full shape

- Previous version: Pulse shape only implemented in range [-75ns, +75ns]

- Improvement: Implemented all available range [-75ns, +130ns]

- This allows to study effect of more ‘distant’ pulses and study set-back phase

(negative values for amplitude for t > 100ns)

Old version:

HG → mis reconstructed saturated pulses LG → excess of events

Implementing a mono-gain system

- Previous version: PS was implemented in bi-gain system → not correct behaviour - Improvement: Implemented gain-switch and mono-gain system

- Same behavior as real detector

- Better handling of saturating event (no duplicated) and mis-reconstructed

New version:

HG → No mis-reco saturated pulses LG → only saturating pulses

SM H → analysis

Object reconstruction

- Particles produced during collisions leave traces in different detectors

- Several algorithms are used to combine information to reconstruct the original particle that produced the detector response

Reconstruction of particles for the analyses

( → e → → jet )

- Tracking and vertexing: points in silicon detectors are used to generate tracks.

Iterative combination of tracks is used to reconstruct the vertices

- Electrons (e): energy deposits in EM calorimeter and matching track. Cut-based (Run 1) and likelihood discriminant (Run 2) are used to set efficiency working points.

- Muons ( ): track segments from ID and Muon Spectrometer - Jets: calibrated clusters of energy deposits in calorimeter

a special algorithm tags the jets coming from a b-quark

- Tau ( ): only visible part of hadronic-decaying is reconstructed as stand-alone object Seed from jets, calibrated, with charge (±1) and prong (1,3) conditions

The -ID is done with a BDT with 3 working points (tight, medium, loose) - E_T^miss: neutrinos ( ) are reconstructed as missing energy in the transverse plane

- Used the data collected during the full Run 1 of LHC

- An integrated luminosity of L = 4.5 fb

⁻¹

at e.c.m 7 TeV in 2011 - An integrated luminosity of L = 20.3 fb

⁻¹

at e.c.m. 8 TeV in 2012.

Datasets

Accumulated luminosity Number of interactions per

bunch-crossing ⁵⁶

- Used the data collected during the first year (2015) of the Run 2 of LHC - An integrated luminosity of L = 3.2 fb

⁻¹

at an e.c.m of 13 TeV and a bunch-spacing of 25 ns - First analysis with Run 2 data!

Datasets

Accumulated luminosity Number of interactions per

bunch-crossing ⁵⁷

- The Higgs boson is produced by three main processes - gluon-fusion (ggH): most abundant process ( 〜 _85%)

- Vector Boson Fusion (VBF):

clear signature with two back-to-back jets

- Vector-associated production (VH): small contribution ( 〜 5%)

Higgs production

ggH VBF VH

ggH VBF WH ZH

σ x BR [pb] 1.22 0.100 0.0445 0.0262

Order NNLO+NNLL (N)NLO NNLO NNLO

- Visible mass (m

_ll

): Invariant mass of the di-lepton system

- Collinear mass (m ): computed assuming the collinear approximation

- The taus are boosted, so their decay products move in same direction

- The system of unknown variables can be resolved if taus are not back-to-back - Since tau are considered massless, approximation is reasonable valid

- Missing Mass Calculator (MMC): algorithm that computes the mass by estimating the exact direction of the neutrinos

- Not all topologies are equally probable

- Using extra info as PDFs e.g. ∆R( ) from Z → process - MMC depends greatly on the E_T^miss accuracy and resolution

Reconstruction of di-tau mass

backup

- Contribution of two light leptons without relevant

^E_T^miss

- Only relevant in Same Flavour events (SF)

- Estimation with MC

- A Control Region (CR) for this bkg is defined under the Z peak

(80-100 GeV)

- A

E_T^miss

correction is derived from CR and applied to Signal Region (SR)

Background: Z → ll

- tt and (single-top) can be source of two light leptons - Events with high

E_T^miss

and several jets, especially b-jets - Estimation with MC

- Background is reduced by vetoing events with a b-tagged jet - A CR for this bkg is defined asking for a b-jet

Background: Top-quark processes

➢ Aim: prove the background are well understood and modeled

● Control Regions: also used in the analysis (normalization for the fit)

- Zll CR: same selection as SR but inverting m_ll condition and only in SF channel - Top CR: same selection as SR but inverting b-veto condition

- Ztt VR: Ztt bkg cannot be separated from signal

● A low-contaminated region can be defined using HP_TO, asking m^HPTO( ) < 100 GeV - Di-boson VR: a OS events, jet-free region

Control and Validation regions (CR / VR)

Ztt VR

At main selection

di-boson VR

Background: Control Regions

VBF Top CR

Boosted Top CR VBF

Zll CR Boosted

Zll CR

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

Control plots of the background modeling

First stage

(cuts 1-6)

Before categorization

(cuts 1-7) ⁶⁴

Agreement between background model and data!

● Distribution of p_T (L2) in Signal Regions of VBF and Boosted categories

Control plots of the background modeling

VBF SR Boosted SR

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

● HERE: Zll CR of VBF and Boosted categories

Control plots of the background modeling

VBF Zll CR Boosted Zll CR

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

● HERE: Top CR of VBF and Boosted categories

Control plots of the background modeling

VBF Zll CR Boosted Zll CR

MVA analysis

MVA Overtraining

Variables definition: Centralities

Variables definition: Sphericity

Variables: VBF

Variables: Boosted

MVA: Cross-checks

Additional Results

- BDT Score for SR, Zll CR and Top CR for VBF and Boosted cats

● BDT Score: value in range [-1, +1] representing compatibility of event with Bkg (-1) or Signal (+1)

● BKG: If there is agreement in low-score region, bkg is well modelled

● SIG: signal is concentrated in last bins, expected as an excess of events over bkg

Results of the _{lep lep} channel: Control Regions

VBF: Zll CR

Plots in backup

VBF: Top CR ⁸⁶

- BDT Score for SR, Zll CR and Top CR for VBF and Boosted cats

● BDT Score: value in range [-1, +1] representing compatibility of event with Bkg (-1) or Signal (+1)

● BKG: If there is agreement in low-score region, bkg is well modelled

● SIG: signal is concentrated in last bins, expected as an excess of events over bkg

Results _{lep lep} channel: Control Regions

Boosted: Zll CR

Plots in backup

Boosted: Top CR ⁸⁷

Results channel: BDT Results: LL

⁸⁸

Results channel: BDT Results: LH

⁸⁹

Results channel: BDT Results: HH

⁹⁰

Results _{lep lep} channel: ^Yields

Results _{lep had} channel: ^Yields

Results _{had had} channel: ^Yields

Results channel: Systematics

⁹⁴

Results channel: ^Results

⁹⁵

Results channel: ^Cut-based

⁹⁶

Results channel: ^Cut-based

For 8 TeV only

MSSM A/H → analysis

MMC Optimization

Example of deviation distribution Events with jets

mH=600, sqrt(sumET) in [32,34]

100

- MET Resolution → Deviation = MET (Reco) - MET (Truth)

- Distributions of deviation for slices of sqrt(sumET), for events with and without jets - Distributions are fitted with gaussian → sigma extracted

- Done for mass points from mH=200 GeV to mH=1400 GeV

Example of deviation distribution Events without jets

mH=600, sqrt(sumET) in [32,34]

MMC Optimization

101

- Sigmas of different slices are plotted together

- Distribution is fitted with linear function, slope is extracted - Fit done for each mass point

MMC Optimization

- Slopes for different masses are reasonable compatible (check table!) - So, repeat study combining mass points

MMC Optimization

103

- Slopes for different masses are reasonable compatible (table!) - So, repeat study combining mass points

MMC Optimization

- Combining mass points: Linear fit and function

MMC Optimization

105

- Comparison of old and new reconstructions

MMC Optimization

Mass discriminant

107

- Comparison of MMC, visible, MOSAIC, mTtot with Asimov Significance

Mass discriminant

109

Additional results

Distributions of m_T^tot for each category in the SR - No excess observed

Results of the _{lep had} : Signal Region

SR b-tag SR b-veto

111

Results _{lep had} channel: ^Yields

Distributions of m_T^tot for inclusive category in the SR No significant excess is observed

Results of the Z’ : Signal Region

Z’ lephad Z’ hadhad

113

Results of the Z’ : Signal Region

Results of the : Systematics

115

Results of the : Extra scenarios

mh mod- mh max

Results of the : Extra scenarios

light stau light stop 117

Results of the : Extra scenarios

tauphobic

In document Measurement of the Higgs boson coupling with tau leptons and search for an additional neutral MSSM Higgs boson with the ATLAS detector (página 46-119)

Conclusions

- This thesis was performed during the Runs 1 and 2 of the LHC, and the Long Shutdown, both in physics analyses and technical tasks of the Tile Calorimeter of the ATLAS detector

- The work of this thesis has contributed to obtain strong evidence of the direct coupling of the Higgs boson to fermions, a result which is fully compatible with the Standard Model

- In addition, it has contributed to expand the non-allowed space of

parameters of one extension beyond the Standard Model, the MSSM, and to prepare the field to the upcoming data of Run 2

Thank you for your attention!

Backup

Enhancement of the Pulse Simulator

Simulation of high pile-up conditions

Extended pulse shape

Implementing a mono-gain system

SM H → analysis

Object reconstruction

Reconstruction of particles for the analyses

- Used the data collected during the full Run 1 of LHC

- An integrated luminosity of L = 4.5 fb

at e.c.m 7 TeV in 2011 - An integrated luminosity of L = 20.3 fb

at e.c.m. 8 TeV in 2012.

Datasets

- Used the data collected during the first year (2015) of the Run 2 of LHC - An integrated luminosity of L = 3.2 fb

Datasets

- The Higgs boson is produced by three main processes - gluon-fusion (ggH): most abundant process ( 〜 85%)

- Vector Boson Fusion (VBF):

- Vector-associated production (VH): small contribution ( 〜 5%)

Higgs production

- Visible mass (m

): Invariant mass of the di-lepton system

- Collinear mass (m ): computed assuming the collinear approximation

- Missing Mass Calculator (MMC): algorithm that computes the mass by estimating the exact direction of the neutrinos

Reconstruction of di-tau mass

- Contribution of two light leptons without relevant

- Only relevant in Same Flavour events (SF)

- Estimation with MC

- A Control Region (CR) for this bkg is defined under the Z peak

- A

correction is derived from CR and applied to Signal Region (SR)

Background: Z → ll

- tt and (single-top) can be source of two light leptons - Events with high

and several jets, especially b-jets - Estimation with MC

- Background is reduced by vetoing events with a b-tagged jet - A CR for this bkg is defined asking for a b-jet

Background: Top-quark processes

➢ Aim: prove the background are well understood and modeled

Control and Validation regions (CR / VR)

Background: Control Regions

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

Control plots of the background modeling

Agreement between background model and data!

Control plots of the background modeling

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

● HERE: Zll CR of VBF and Boosted categories

Control plots of the background modeling

Agreement between background model and data!

● Distribution of p

(L2) at different stages!

● HERE: Top CR of VBF and Boosted categories

Control plots of the background modeling

MVA analysis

MVA Overtraining

Variables definition: Centralities

Variables definition: Sphericity

Variables: VBF

Variables: VBF

Variables: Boosted

Variables: Boosted

Variables: Boosted

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

MVA: Cross-checks

Additional Results

Results of the lep lep channel: Control Regions

- The Higgs boson is produced by three main processes - gluon-fusion (ggH): most abundant process ( 〜 _85%)

Results of the _{lep lep} channel: Control Regions

Results _{lep lep} channel: Control Regions

Results _{lep lep} channel: ^Yields

Results _{lep had} channel: ^Yields

Results _{had had} channel: ^Yields

Results channel: ^Results

Results channel: ^Cut-based

Results channel: ^Cut-based

Results of the _{lep had} : Signal Region

Results _{lep had} channel: ^Yields