Bsquedas de nueva fsica a travs de ATLAS y CMS M a r c e l l - - PowerPoint PPT Presentation

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• Búsquedas de nueva física

a través de ATLAS y CMS

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X X X I I I R e u n i ó n A n u a l d e l a D i v i s i ó n d e P a r t í c u l a s y C a mp

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• Searches for new physics

at ATLAS and CMS

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Direct searches for BSM phenomena: evidence of new physics

◎ Resonant searches ◎ Non-resonant searches ◎ Weak couplings ◎ Unconventional signatures

All the ways towards new physics

Indirect searches: deviations from the SM in precision measurements

◎ Flavour Physics ◎ Electroweak physics

◉ Higgs boson properties ◉ W and Z bosons ◉ Multibosons

Interference between direct and indirect:

◎ From the all the searches above we know that if new

particles or interactions exist in this kinematic range, they have complex signatures or low rates

◉ room for discovery with sophisticated analyses and at

future upgrades This talk

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Example: scale analysis from global flavour fits

B(s) systems are giving us a rather precise picture

However there is some space for NP Could appear as new contributions in ΔF=2 loop processes

Via loop processes flavour can be sensitive to new physics particles at even higher scales than the direct searches At the low scale, we can use OPE to write the most general effective Hamiltonian with the operators that have different chiralities than the SM NP effects are in the Wilson coefficients C ∝ 1/Λ2 with Λ the new particle mass in case of loop coupling of NP through weak interactions in NMFV models Λ > 2.7 TeV

[0707.0636 hep-ph] Updates on utfit.org

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Some excitement in B physics: B anomalies..

Lepton Universality tests in b to s/c

R(D(*)) = BR(B → D(*)τ ν )/BR(B → D(*)ℓν ) ~3σ effect R(K) → 2.5σ effect R(K(*)) = BR(B → K(*)μ μ )/BR(B → K(*)ee)

b to s anomalies 1-loop processes in the SM The scale of NP can be “high” Λ ~ 30-50 TeV b to c anomalies tree processes in the SM The scale of NP must be “low” Λ ~ TeV

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Leptoquark searches

arXiv:1902.08103

36 fb-1 of Run 2 pair-production of 3rd-generation scalar LQ(u,d) into 3rd-generation SM particles Multiple final states: bτ bτ / tt + ET

miss / ττ b + Et miss / bb + ET miss

Results: masses below 800 GeV are excluded for both LQu

3 and LQd 3 (any BR)

masses below about 1 TeV being excluded for BR equal to zero or unity.

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Direct searches for BSM phenomena: evidence of new physics

◎ Resonant searches ◎ Non-resonant searches ◎ Weak couplings ◎ Unconventional signatures

Dilepton resonant searches Dijet resonant searches Boosted dijet resonance with ISR Resonant searches with dibosons Search for gluinos and squarks Search for Electroweak Processes Extremely Rare Processes: Stau Search Search for Heavy Neutrinos Long Lived Massive Particle Search Disappearing Track Search Dark Matter searches Resonant searches SUSY searches Non conventional signatures

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Resonant searches

Heavy resonances predicted by several BSM theories:

spin-2 Graviton as Kaluza-Klein excitations in models of extra dimensions (Randall-Sundrum) spin-1 W’ and Z’ as in models of compositeness

• r with extended gauge symmetries

(SSM, E6 GUT) can appear as singlet or triplet (eg, Heavy Vector Triplet) spin-0 Radions as in extensions of original RS model or Higgs-like particle as in MSSM excited quarks as in models of compositeness

Can be produced directly at the LHC through gluon fusion, qq annihilation or VBF high discovery potential!

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Resonant searches

Common strategy: reconstruct invariant mass of decay products and search for “bumps” on smoothly falling SM background Main challenge: reconstruction of highly energetic objects in the final state to maximize signal efficiency pileup mitigation, jet substructure, lepton isolation, lepton-in-jet subtraction, ... different approaches in ATLAS and CMS leading to similar or complementary sensitivities Dilepton resonant searches Dijet resonant searches Boosted dijet resonance with ISR Resonant searches with dibosons

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Dilepton Resonance Search

arXiv:1903.06248

Search for bumps in dilepton mass spectrum New with full Run-2 139 fb-1

better lepton reconstruction: new dynamical cell-clustering algorithm for electrons improved inner tracker so better alignment for muons

Sensitivity dominated by dielectrons: better reconstruction, identification efficiency and mass resolution Main backgrounds: Drell-Yan, top, diboson, fake electrons from QCD Background estimated with smooth functional form based on fit studies on MC background template Improved signal description: non-relativistic Breit-Wigner function (various widths) convolved with the detector resolution

225 < mℓℓ < 6000 GeV

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Dilepton Resonance Search

arXiv:1903.06248

Resonances decaying to dilepton excluded below masses of 4-5 TeV Limits and significance provided also as a function of the width (up to ΓX/MX = 10%) Limits also presented on simplified Heavy Vector Triplet (HVT) couplings

Excluded for resonant masses of 3 TeV

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Dijet Resonance Search

ATLAS-CONF-2019-007

New with full Run-2 139 fb-1 Searches for BSM signals up to high masses decaying to a pair of jets QCD predicts a smoothly falling distribution for dijet invariant mass New resonant state may appear as a localised excess near the mass of the resonance Requires two high-pT jets with mjj > 1.1 TeV (limited by online hadronic trigger) Background estimated by a fit to the mjj spectrum in data with empirical smoothly falling parametric function: variable bin width, sliding window method

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Dijet Resonance Search

ATLAS-CONF-2019-007

Extended previous mass exclusion limits for excited quarks from 6 TeV (37 fb-1) to 6.7 TeV Set limits also on hypothetical process that produces a Gaussian contribution of different widths (up to ΓX/MX = 15%)

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Low-mass Dijet Resonance + ISR jet

CMS-EXO-18-012

New with 77 fb-1 of Run-2 Search for a light vector resonance Z’ with masses 50-450 GeV Extend to lower resonance masses, boosted event topology with resonance recoiling against significant ISR jet Extends previous search to higher jet mass by adding a jet clustering algorithm with a larger distance parameter R: R=0.8 (<175 GeV) R=1.5 (>175 GeV) Use jet substructure algorithms to suppress QCD binned maximum likelihood fit to the shape of the mass (mSD) distribution 5 pT categories for AK8 jets and 4 pT categories for CA15 jets,

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Low-mass Dijet Resonance + ISR jet

CMS-EXO-18-012

In previous search with 2016 data local excess of 3.1σ @ 120 GeV, not confirmed by this search Limits set on the coupling to quarks g’q versus Z’ mass Combination with previous analysis that used R=0.8 jets only improvement of 20% ∼20&

EXO-17-001

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D i j e t R e s

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Large effort to search the whole mass range by exploiting new ideas and technologies: use ISR jet/photon to access low masses use novel data scouting (CMS) and trigger level analysis (ATLAS) to access the intermediate range

Jennifer Ngadiuba’s talk @LHCP2019

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X → t t r e s

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All-hadronic final state (largest BR=45.7%) Dedicated top-quark reconstruction and identification techniques to suppress QCD Resolved and boosted event analyses employed in parallel Many event categories (signal and control regions) based on b-tagging, jet substructure, jet mass, top quark compatibility Data-driven estimation of multi-jet and W+jets backgrounds, tt estimated from MC

• Phys. Rev. D 99, 092004

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X → t t r e s

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Companion CMS search with 35.9 fb-1: 3 individual analyses: 0,1,2 lepton channels full combination of the 3 results Similar interpretations for CMS and ATLAS: set limits on various resonance spin and width (up to 40% for gKK)

• Phys. Rev. D 99, 092004

JHEP 04 (2019) 031

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D i b

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New with full Run-2 139 fb-1 2 high-pT merged W/Z→qq jets Improved boson-jet reconstruction with track-calo cluster algorithm combine good calorimeter energy resolution with good tracker angular resolution to resolve jet substructure at high-pT Identification of boosted bosons versus q/g jets based on selection dependent on jet pT 3 V-jet tagging variables simultaneously optimized to account for correlations Multijet background estimated empirically from the observed mjj spectrum in the signal region using parametric function (validated in a control region)

ATLAS-CONF-2019-003

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D i b

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Companion CMS search based on 77 fb-1 Novel background estimation: standard 1D mjj bump-hunt 3D ( m

• jj, mjet1, mjet2 ) bump-hunt

Switched to new more performant boson-jet tagger jet pT/mass-decorrelated N-subjettiness (τ21

DDT)

decorrelation ensures smooth QCD jet mass shapes and reduce 3-variables correlations Modeling of correlations in QCD bkg from smooth MC-based template nominal shape allowed to adjust to data among large alternative shapes Measurement of SM V→qq in the final fit allows to constrain signal syst New strategy improves results by 20-30% beyond the added dataset

B2G-18-002

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D i b

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Same interpretations for ATLAS and CMS for spin-1 W’/Z’ resonances in the heavy vector triplet model excluded below masses of 3-3.8 TeV For spin-2 gravitons, they assumed different widths: 0-width in CMS and larger width for ATLAS

ATLAS-CONF-2019-003 B2G-18-002

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SUSY searches

Gluinos and squarks have largest cross sections Simplified SUSY mass spectrum, representative of certain parameter space. Design analyses targeting all possible models. Comprehensive scans (e.g. pMSSM) provide more generic constraints on SUSY MET in all RPC signatures SUSY partners regulate Higgs mass radiative corrections. Naturalness favours light stop, gluino and Higgsino.

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Third generation searches

Natural SUSY scenarios predict light third generation quarks - can be produced at the LHC Decay to lightest supersymmetric particle (LSP) LSP: light, stable DM candidate Rich in experimental signatures common to other BSM scenarios Direct production Gluino-mediated production

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Stop searches

Increase in LHC energy increased the reach in high stop and neutralino mass with Run 2 data Signal topologies: 0, 1, or 2 leptons Missing transverse momentum (MET) from neutralinos ≥ 2 jets (some b-tagged jets) depends on: decay mode additional jets mass splittings, Δm( t, χ1

0 )

increasing N jets: decreases the boost and gives unmerged products decreasing N jets: increases the boost and the top products are merged

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S t

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ATLAS-CONF-2019-017

New with full Run-2 139 fb-1 3 body decay: complicated topology due to soft decay products and overwhelming background 1 lepton + ≥ 4 jets (≥ 1 b-tagged jets) + MET strong 2nd lepton vetoes additional jets: ISR needed to boost the system so that LSP can be boosted and give high MET

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S t

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ATLAS-CONF-2019-017

10 Signal Regions binned by NN score Control region and validation region created in NN score sidebands No significant excess

• bserved

Large improvement from previous limits: exclusion up to ~700 GeV in stop mass

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S t a u s e a r c h e s

Motivation to search for direct stau production complement searches for models with stau in decay chains Can help obtain relic DM density consistent with astronomical obs. Challenging searches weakly produced→low xsec τhτh final state most sensitive high QCD background difficult to identify hadronic tau decays

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S t a u s e a r c h e s

ATLAS-CONF-2019-018

New with full Run-2 139 fb-1 Only τhτh channel 2 orthogonal SRs to target low and high stau masses Main backgrounds are multi-jet, W+jets and diboson production

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S t a u s e a r c h e s

ATLAS-CONF-2019-018

World’s best stau limits Limits derived in scenarios of direct production of two mass-degenerate staus in simplified models Stau masses from 120 GeV to 390 GeV @95% are excluded for a massless lightest neutralino in the scenario of the combined left- and right-handed τR,LτR,L production. For the left-handed production only, exclusion extends from 160 GeV to 300 GeV.

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C

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ATLAS and CMS have a comprehensive program of searches for new physics Results are starting to become available with the full Run 2 dataset with 137-139 fb-1! No significant excess has been observed yet. Begin to move beyond simplified models, explore more complex decay chains. Going after some of the uncovered and more challenging areas with a new set of tools to analyse (machine learning) and to identify tops, b's and taus. A lot more results to be found here: ATLAS: https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ExoticsPublicResults

CMS: https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSUS

https://cms-results.web.cern.ch/cms-results/public-results/publications/EXO/index.html https://cms-results.web.cern.ch/cms-results/public-results/publications/B2G/index.html

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Back up slides