Búsquedas de nueva física a través de ATLAS y CMS M a r c e l l a B o n a R e i n a M a r í a U n i v e r s i t a d d e L o n d r e s 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 o s d e l a S o c i e d a d M e x i c a n a d e F í s i c a 2 6 d e M a y o d e 2 0 1 9 P u e b l a , M e x i c o
Searches for new physics at ATLAS and CMS M a r c e l l a B o n a Q u e e n M a r y U n i v e r s i t y o f L o n d o n ( Q M U L ) 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 o s d e l a S o c i e d a d M e x i c a n a d e F í s i c a 2 6 d e M a y o d e 2 0 1 9 P u e b l a , M e x i c o
All the ways towards new physics This talk Indirect searches: deviations from the SM in precision Direct searches for BSM measurements phenomena: evidence of new physics ◎ Flavour Physics ◎ Resonant searches ◎ Electroweak physics ◎ Non-resonant searches ◉ Higgs boson properties ◎ Weak couplings ◉ W and Z bosons ◎ Unconventional signatures ◉ 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 3 Ma r c e l l a B o n a ( Q MU L )
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 [0707.0636 hep-ph] to write the most general effective Updates on utfit.org Hamiltonian with the operators that have different chiralities than the SM NP effects are in the Wilson coefficients C ∝ 1/Λ 2 with Λ the new particle mass in case of loop coupling of NP through weak interactions in NMFV models Λ > 2.7 TeV 4 Ma r c e l l a B o n a ( Q MU L )
Some excitement in B physics: B anomalies.. Lepton Universality tests in b to s/c R(D ( * ) ) = BR(B → D ( * ) τ )/BR(B → D ( * ) ℓ ν ) ν R(K) → 2.5 σ effect ~3 σ effect R(K ( * ) ) = BR(B → K ( * ) μ )/BR(B → K ( * ) ee) μ b to s anomalies b to c anomalies 1-loop processes in the SM tree processes in the SM The scale of NP can be “high” The scale of NP must be “low” ~ 30-50 TeV ~ TeV Λ Λ 5 Ma r c e l l a B o n a ( Q MU L )
arXiv:1902.08103 Leptoquark searches 36 fb -1 of Run 2 pair-production of 3 rd -generation scalar LQ (u,d) into 3 rd -generation SM particles Multiple final states: bτ bτ / tt + E T miss / ττ b + E t miss / bb + E T miss Results: masses below 800 GeV are excluded for both LQ u 3 and LQ d 3 (any BR) masses below about 1 TeV being excluded for BR equal to zero or unity. 6 Ma r c e l l a B o n a ( Q MU L )
Direct searches for BSM phenomena: evidence of new physics Resonant searches ◎ Resonant searches ◎ Non-resonant searches Dilepton resonant searches ◎ Weak couplings Dijet resonant searches ◎ Unconventional signatures Boosted dijet resonance with ISR Resonant searches with dibosons SUSY searches Search for gluinos and squarks Search for Electroweak Processes Non conventional signatures Extremely Rare Processes: Long Lived Massive Stau Search Particle Search Search for Heavy Neutrinos Disappearing Track Search Dark Matter searches 7 Ma r c e l l a B o n a ( Q MU L )
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 or 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! 8 Ma r c e l l a B o n a ( Q MU L )
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 9 Ma r c e l l a B o n a ( Q MU L )
arXiv:1903.06248 Dilepton Resonance Search 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, 225 < m ℓℓ < 6000 GeV 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 10 Ma r c e l l a B o n a ( Q MU L )
arXiv:1903.06248 Dilepton Resonance Search Resonances decaying to dilepton excluded below masses of 4-5 TeV Limits and significance provided also as a function of the width (up to Γ X /M X = 10%) Limits also presented on simplified Heavy Vector Triplet (HVT) couplings Excluded for resonant masses of 3 TeV 11 Ma r c e l l a B o n a ( Q MU L )
ATLAS-CONF-2019-007 Dijet Resonance Search 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-p T jets with m jj > 1.1 TeV (limited by online hadronic trigger) Background estimated by a fit to the m jj spectrum in data with empirical smoothly falling parametric function: variable bin width, sliding window method 12 Ma r c e l l a B o n a ( Q MU L )
ATLAS-CONF-2019-007 Dijet Resonance Search 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 Γ X /M X = 15%) 13 Ma r c e l l a B o n a ( Q MU L )
CMS-EXO-18-012 Low-mass Dijet Resonance + ISR jet 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 (m SD ) distribution 5 p T categories for AK8 jets and 4 p T categories for CA15 jets, 14 Ma r c e l l a B o n a ( Q MU L )
CMS-EXO-18-012 Low-mass Dijet Resonance + ISR jet 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 15 Ma r c e l l a B o n a ( Q MU L )
D i j e t R e s o n a n t s e a r c h e s : s u mma r y 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 16 Ma r c e l l a B o n a ( Q MU L )
Phys. Rev. D 99, 092004 X → t t r e s o n a n c e s e a r c h e s 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 17 Ma r c e l l a B o n a ( Q MU L )
Phys. Rev. D 99, 092004 X → t t r e s o n a n c e s e a r c h e s JHEP 04 (2019) 031 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 g KK ) 18 Ma r c e l l a B o n a ( Q MU L )
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