Moriond EW 2017 La Thuile. Wouter Hulsbergen (Nikhef, LHCb) on behalf of the ATLAS, CMS and LHCb collaboraeons

Transcription

1 Moriond EW 07 La Thuile Wouter Hulsbergen (Nikhef, LHCb) on behalf of the ATLAS, CMS and LHCb collaboraeons

2 Long-lived parecles at the LHC apple long-lived parecles (LLPs): resonances that live long enough to escape the detector P decay in the detector, but far enough from the PinteracEon point that the decay length can be measured ± L & mm LLPs at the LHC necessarily have lifeeme τ > ~ ps characterisec of weak decays narrow resonances (as Γ = h/τ)

3 Long-lived parecles in the Standard Model ] mass [ GeV/c leptons strange hadrons charm hadrons beauty hadrons τ ± KS ± K KL neutron 0 π π ± µ ± lifetime [ s ] weak decays are backgrounds for LLP searches LHC experiments look for parecles that do not fit this picture 3

4 DetecEon signatures at the LHC stable massive charged large de/dx slow (large Eme-of-flight) see talk by Aniello Spiezia stable neutral missing energy see SUSY and LHC DM talks meta-stable charged disappearing track see talk by Toshiaki Kaji meta-stable neutral displaced vertex/tracks jets without tracks main subject of this talk 4

5 What makes a parecle long-lived? textbook formula for lifeeme of the charged pion: small coupling constant r small mass spli`ng h = = f 56 m 6 4 g M W m µ m m m µ heavy messenger helicity suppression many examples in SUSY: small couplings: R-parity violaeng couplings, graviton LSP small mass spli`ng: Next-to-Lightest-SP heavy messenger: heavy squarks, Z-prime 5

6 One popular scenario: Hidden Valley quarks and leptons dark sector energy conneceon via heavy messenger or kineec mixing new long-lived parecle stable DM candidate scenario got renewed interest because of neutral/uncolored naturalness top partner coloured under a different SU(3) gauge group dark sector has its own hadronizaeon/confinement Higgs mixes with dark sector scalar and decays to dark sector parecles (see e.g. CurEn and Verhaaren, arxiv: ; Craig e.a., arxiv:50.053v, 6

7 Hidden Valley via a Higgs Portal SM Higgs mixes with scalar in hidden sector meta-stable dark sector parecle f t H 0 V f t V f Higgs-like coupling kinemaecs known (e.g. SM Higgs produceon) LLP decays prefereneally to heavy fermions (b,c,τ) f three parameters: m(h), m(π v ), τ(π v ) signature most studied: displaced jets alternaeve: fragmentaeon in hidden sector à emerging jets 7

8 LLP searches at the LHC wide program: see e.g. program of LHC LLP workshops ATLAS and CMS are well suited: large luminosity, efficient triggers, excellent tracking/calorimetry new in run-: topological triggers LHCb collects less luminosity, but is more efficient at low mass and lifeeme 53*((&3 "/% 7&35&9 3&$0/4536$5*0/ modest p T requirements; vertex triggers at very high rate common experimental issues, e.g. backgrounds: weak decays of heavy flavour material interaceons cosmic muons beam halo muons b b 8

9 Selected results ATLAS at 3 TeV: neutral LLP in calo (ATLAS-CONF-06-3) displaced lepton jets (ATLAS-CONF-06-04) CMS at 3 TeV,.6/t: displaced e-mu pairs (CMS PAS-EXO-06-0) inclusive displaced jets (CMS PAS-EXO ) LHCb at 7/8 TeV: displaced vertex with muon (LHCb-PAPER ) hidden valley pions decaying to di-jets (LHCb-PAPER ) scalar resonances in B Kμμ (LHCb-PAPER-06-5) 9

10 Inclusive displaced jets at 3 TeV at CMS CMS-PAS-EXO two models: Jet-Jet : H π V π V 4 quarks B-lepton : top squark pair produceon with lepton number violaeng decays t b µ + signature: 4 displaced hadronic jets displaced hadronic jets + evt. tau jets t analysis exploits topological triggers : high-p T jets with tracks compaeble with beam-line b Jets / 0.0 CMS Preliminary -.6 fb (3 TeV) mm mm 0mm 00mm QCD Data off-line seleceon uses several observables to enhance fraceon of displaced jets, e.g. max of sum p T associated to single PV Jet α max

11 Inclusive displaced jets at 3 TeV at CMS q CMS-PAS-EXO events with tagged jet used apple to esemate mistag probability as funceon of #tracks à allows to esemate per-event background yield in signal region in.6/t at 3 TeV: P P tracks N tags observed expected.09 ± (4.9 ±.0) 4 interpretaeon in models: T Jet-Jet model B-tau model (top squark) top squark results are most constraining for long-lived stops to date

12 Heavy Higgs decays to track-less jets at ATLAS ATLAS-CONF-06-3 model: heavy Higgs mixing with dark sector scalar signature: events with hadronic jets without tracks finite region in decay length: barrel:.0 < R xy < 3.6 m end-cap: 4. < R z < 5.4 m search tuned for LLPs with mass 0-50 GeV, pair produced in the decay of a scalar of GeV p p s s f f f f main backgrounds mule-jet background cosmics beam-halo muons main discriminants fraceon of hadronic energy ( CalRaEo ) jet width proximity of high-pt tracks to jet axis calo cluster Eme

13 Heavy Higgs decays to track-less jets at ATLAS ATLAS-CONF % CL Upper on σ BR [pb] 95% CL Upper Limit on σ x BR [pb] event yield in 3./; at 3 TeV: 4 observed 8.0 ± 6.3 expected background limits as funceon of lifeeme for different values of m φ and m S -I s = 3 TeV 3. fb m Φ = 400 GeV m s = 50 GeV m s = 0 GeV ATLAS Preliminary m φ =400 GeV BR [pb] 95% CL Upper Limit on σ s proper decay length [m] -I s = 3 TeV 3. fb m Φ = 600 GeV m s = 50 GeV m s = 50 GeV ATLAS Preliminary m φ =600 GeV BR [pb] 95% CL Upper Limit on σ s proper decay length [m] -I s = 3 TeV 3. fb m Φ = 00 GeV m s = 50 GeV m s = 50 GeV m s = 400 GeV ATLAS Preliminary in sensieve region 95%CL upper limits in range 0.- pb best sensievity obtained for lifeemes in range ns BR [pb] 95% CL Upper Limit on σ m φ =00 GeV -I s = 3 TeV 3. fb s proper decay length [m] m Φ = 00 GeV m s = 50 GeV m s = 50 GeV m s = 400 GeV ATLAS Prelimina 3

14 Hidden Valley v-pions decaying to jet pairs at LHCb model: Higgs decay to two LLPs each decaying to two fermions LHCb-PAPER H 0 V V b b b b LHCb signature: single displaced vertex with two associated jets (LHCb acceptance for all 4 jets is small, only few %) QCD background analysis strategy trigger on displaced vertex find two associated jets extract signal from fit to di-jet mass in bins of distance to beam axis (R xy ) Candidates / (GeV/c ) 4 3 LHCb,.0/t, 7,8 TeV preliminary LHCb 3.0 < R xy < 5.0 mm hypotheecal 35 GeV signal Mass (GeV/c ) 4

15 LHCb Hidden Valley v-pions decaying to jet pairs at LHCb no excess above background in.0/t of 7/8 TeV data place 95% CL upper limits on BR( H 0 (5) π V π V, π V bb ) for 5 < m < 50 GeV and < τ < 500 ps most sensieve point (m=50 GeV, t= ps) exclude BR > % 95% CL Upper Limit on σ / σ SM arxiv: m π m π m π = GeV V =5 GeV V =40 GeV V ATLAS - - s = 8 TeV, 9.5 fb, 0.3 fb m H = 5 GeV π v arxiv: m π m π m π = GeV V =5 GeV V =40 GeV V (σ/σ SM gg H 0) (H0 π v π v ) BR 5% BR 5% BR % proper lifetime (cτ) [m] 3 m πv = 5 GeV/c m πv = 35 GeV/c m πv = 43 GeV/c m πv = 50 GeV/c m πv m πv = 35 GeV/c, π v cc = 35 GeV/c, π v ss LHCb-PAPER LHCb.0/t, LHCb 7,8 TeV preliminary 3 lifetime (ps) compared to similar analyses from ATLAS (le ) and CMS, LHCb is more sensieve in region with small mass and lifeeme 5

16 Displaced lepton jets at 3 TeV at ATLAS (see also V. MarEnez Outschoorn in Sunday session!) FRVZ (*) model: Higgs decays to dark sector fermions, that radiate dark photons decaying to lepton pairs lightest stable dark parecle dark sector fermion HLSP photon portal ATLAS-CONF γ d H f d f d HLSP l + l - collimated leptons Higgs portal γ d search strategy: look for events with or 4 jets consiseng of pairs of muons, electrons or pions without tracks l - l + (*) Falkowski-Ruerman-Volansky-Zupan, JHEP05(0)077, PRL5(0)480 6

17 Displaced lepton jets at 3 TeV at ATLAS ATLAS-CONF observed event yields in 3.4/t compaeble with background observed exp.bkg. H(5) γ d + X H(5) 4 γ d + X 46 3 ± 9 ± 96 ± results interpreted in FRVZ model with dark photon mass of 400 MeV: RFVZ +X) [pb] 95% CL Limit on σ BR(H γ d ATLAS Preliminary fb, s = 3 TeV FRVZ γ model BR(H γ +X) = 0% d BR(H γ +X) = % d d m H = 5 GeV m γ = 400 MeV d +X) [pb] 95% CL Limit on σ BR(H 4γ d ATLAS Preliminary fb, s = 3 TeV FRVZ 4γ model d m H = 5 GeV m γ = 400 MeV BR(H 4γ +X) = 0% d BR(H 4γ +X) = % d d 95%CL limit on BR(H (4) γ d +X) versus dark photon lifefme observed limit expected limit expected ± σ expected ± σ observed limit expected limit expected ± σ expected ± σ Dark photon cτ [mm] Dark photon cτ [mm] Higgs branching fraceon larger than % excluded for < cτ < mm see paper for limits on model with Higgs of 800 GeV 3 7

18 Displaced e-mu pairs at 3 TeV at CMS model: top squark pair produceon with lepton number violaeng R-parity violaeon signature: displaced, non-vertexed muon-electron pairs t t CMS-PAS-EXO-6-0 b e + µ electron impact parameter main background: semileptonic b and c decays e d0 [μm] shape esemated using B-tagged tag-and-probe method yield esemated with ABCD method CR I CR III CR II SR I SR II CR IV μ d 0 [μm] SR III muon impact parameter control region (electron replaced with B-tagged jet) < Entries / µm > (Bkgd. Scaled to Data) CMS Preliminary muon d [µm] 0 b pb (3 TeV) Data stat. errors HF tt W lν Single top + - Z l l diboson muon impact parameter 8

19 Displaced e-mu pairs at 3 TeV at CMS CMS-PAS-EXO-6-0 event yield in different signal regions in.6 t - at 3 TeV e d0 [μm] CR I CR III CR II SR I SR II CR IV SR III μ d 0 [μm] SR esemated background observed expected stop (cm,700 GeV) III < ± 0.3 II < ± 0.3 I < ± 0.4 interpretaeon in context of stop pair produceon, for simplified model with decoupled squarks and gluinos: similar displaced di-lepton analyses in RUN- data: CMS, PRL4(5)0680 ATLAS,PRD9(05)07004 top squark cτ [cm] [cm] top squark cτ - - CMS Preliminary ± std. deviation ± std. deviation Expected Observed -.6 fb (3 TeV) top squark mass [GeV] top squark mass [GeV] exclusion limit at 95% CL 9

20 Entries/( G Semi-leptonic LLP decays at LHCb at 7 and 8 TeV Entries/(.5 GeV/c ) model: msugra neutralino decaying to a lepton and quarks signature: single displaced vertex with muon LHCb Data 8 TeV Fit: total background signal c) m χ = 38 GeV LLP mass [GeV/c ] Entries/( GeV/c ) LHCb H 0 0 Data 8 TeV Fit: total background signal d) LLP mass [GeV/c ] result: no excess above background, at 7 and 8 TeV one example of H(5) χχ limit Figure 3: Reconstructed mass of the LLP candidate from the 8 TeV dataset. The two top plots correspond interpretaeon to eventsin with various candidates models, selecteda.o. from the background region of the muon isolation variable. They are fitted with the sum of two exponential functions. In the bottom row the candidates non-resonant from thesignal neutralino region areproduceon fitted including LHCba specific signal shape, added to p the background produceon component. in Subfigures squark a) decays and c) correspond s =8 to TeV the analysis which assumes the LV38 5 ps signal model, b) and d) are for LV98 ps. Cross-section [pb] produceon in Higgs decays (see right) as funceon of χ mass and lifeeme LLP =5ps at most sensieve - point (~50GeV, ~ps) reject BR(H χχ) > % LLP mass signal yield extracted from fit to vertex invariant mass [GeV/c ] Cross-section [pb] - LLP =ps LHCb-PAPER LLP mass u d µ LHCb p s =8 TeV 0 [GeV/c ]

21 B + Long lifetime: Hidden sector χ μ + μ - b in B + K + μ + μ - at LHCb t b s quark transieons give access to new light narrow scalar resonances (prompt) axion (e.g. Freytsis, LigeE and Thaler, arxiv: ) (long-lived) inflaton (e.g. Bezrukov and Gorbunov, arxiv: ) t via mixing with SM Higgs u u b t s H 0 µ e + b µ + K + 5of3 Inflaton [JHEP05(0)0] Displaced vertex Almost background free Lower reconstruction e LHCb-PAPER K μ ciency μ experimental method: search for narrow peak in μμ invariant mass in B Kμμ decays, in 3 different μμ lifeeme bins normalize to 6 B J/ψ K decays ) Candidates / ( 3.3 MeV/c LHCb Data Signal Background m(b ) [MeV/c ]

22 ] [rad θ Hidden sector χ μ + μ - in B + K + μ + μ - at LHCb no signal above background in 3.0/t of 7/8 TeV data obtained 95% CL on branching fraceon as funceon of m χ and τ χ white areas excluded because of backgrounds from Ks, φ(40), J/ψ, ψ(s) and ψ(460) 4 5 Theory CHARM LHCb 95% CL B 0 K * 0 χ + + B K χ ~ = = 8 m 4M W f m µ m m µ = = f 56 m jet (PV) = apple g M W m µ m PtracksPV ptracks T Ptracks ptracks T N tags observed expected.09 ± (4.9 ±.0) 4 L & mm & ps interpretaeon in inflaton model: LHCb-PAPER m m µ B(B +! K + ) / Higgs-inflaton ( ) / / mixing Theory Cosmological constraints [GeV/c ] m χ à most of parameter space excluded similar searches for LLPs in B decays: χ μμ in B K*μμ (PRL 5, 680 (05)) N μπ in B πμμ (PRL,380 (04))

23 Summary long-lived parecle signature is well-moevated and gaining in popularity R-parity violaeng SUSY, sterile neutrinos, hidden valleys wide variety of searches this talk: new results on signatures with a displaced vertex for other signatures, see talks by Spiezia and Kaji no discovery so far but we keep looking! next LHC LLP workshop (CERN, 4-6 April 07) hžps://indico.cern.ch/event/60734/ missing signatures triggers recaseng 3

24 BACKUP 4

25 ATLAS Long-lived Particle Searches* - 95% CL Exclusion Status: July 05 Model Signature L dt[fb ] Lifetime limit Reference RPV χ 0 eeν/eµν/µµν displaced lepton pair 0.3 χ mm m( g) =.3TeV, m(χ0 )=.0TeV lifetime ATLAS Preliminary L dt =( )fb s =8TeV GGM χ 0 Z G displaced vtx + jets 0.3 χ mm m( g) =.TeV, m(χ 0 )=.0TeV lifetime SUSY AMSB pp χ ± χ0, χ+ χ disappearing track 0.3 χ ± m(χ ± lifetime m )=450GeV AMSB pp χ ± χ0, χ+ χ large pixel de/dx 8.4 χ ± m(χ ± lifetime m )=450GeV GMSB non-pointing or delayed γ 0.3 χ m SPS8 with Λ=00TeV lifetime Stealth SUSY ID/MSvertices 9.5 S lifetime m m( g) =500GeV Hidden Valley H π vπ v low-emftracklessjets 0.3 π v lifetime m m(π v)=5gev Higgs BR = % Hidden Valley H π vπ v ID/MSvertices 9.5 π v lifetime m m(π v)=5gev FRVZ H γ d + X e, µ, π jets 0.3 γ d lifetime 4-40 mm H γ d + X, m(γ d )=400MeV FRVZ H 4γ d + X e, µ, π jets 0.3 γ d lifetime 5-60 mm H 4γ d + X, m(γ d )=400MeV Higgs BR = 5% 300 GeV scalar Hidden Valley H π vπ v low-emftracklessjets 0.3 π v lifetime m m(π v)=5gev Hidden Valley H π vπ v ID/MSvertices 9.5 π v lifetime m m(π v)=5gev FRVZ H 4γ d + X e, µ, π jets 0.3 γ d lifetime 8-60 mm H 4γ d + X, m(γ d )=400MeV Hidden Valley Φ π vπ v low-emftracklessjets 0.3 π v lifetime m σ BR = pb, m(π v)=50gev Hidden Valley Φ π vπ v ID/MSvertices 9.5 π v lifetime m σ BR = pb, m(π v)=50gev GeV scalar Hidden Valley Φ π vπ v low-emftracklessjets 0.3 π v lifetime m σ BR = pb, m(π v)=50gev Hidden Valley Φ π vπ v ID/MSvertices 9.5 π v lifetime m σ BR = pb, m(π v)=50gev Other HV Z ( TeV) q vq v ID/MSvertices 0.3 π v lifetime m σ BR = pb, m(π v)=50gev HV Z ( TeV) q vq v ID/MSvertices 0.3 π v lifetime 0.-. m σ BR = pb, m(π v)=50gev s =8TeV cτ [m] *Only a selection of the available lifetime limits on new states is shown. hžps://twiki.cern.ch/twiki/bin/view/atlaspublic/exoecspublicresults hžps://twiki.cern.ch/twiki/bin/view/atlaspublic/supersymmetrypublicresults 5

26 ~ ~ RPV SUSY, t bl, m( t) = 40 GeV - 8 TeV, 9.7 fb (displaced leptons) CMS long-lived particle searches, lifetime exclusions at 95% CL H XX (%), X ee, m(h) = 5 GeV, m(x) = 0 GeV - 8 TeV, 9.6 fb H XX (%), X µµ, m(h) = 5 GeV, m(x) = 0 GeV - 8 TeV, 0.5 fb 0 0 GMSB SPS8, χ G ~ γ, m( χ ) = 50 GeV ~ 0 RPV SUSY, m( q) = 00 GeV, m( χ ) = 50 GeV ~ 0 RPV SUSY, m( q) = 00 GeV, m( χ ) = 500 GeV ± ± 0 ± AMSB χ, χ χ + π ±, m( χ ) = 00 GeV cloud model R-hadron, m( ~ g) = 00 GeV ± ± AMSB χ, tan(β) = 5, µ > 0, m( χ ) = 800 GeV ± ± AMSB χ, tan(β) = 5, µ > 0, m( χ ) = 00 GeV - 8 TeV, 8.5 fb - 8 TeV, 8.5 fb 8 TeV, 9.7 fb 0 0 GMSB SPS8, χ G ~ γ, m( χ ) = 50 GeV 8 TeV, 9. fb - 8 TeV, 9.5 fb TeV, 8.6 fb - 8 TeV, 8.8 fb - 8 TeV, 8.8 fb (displaced leptons) (displaced leptons) (disp. photon conv.) (disp. photon timing) (displaced dijets) (displaced dijets) (disappearing tracks) (stopped particle) (tracker + TOF) (tracker + TOF) cτ [m] hžps://twiki.cern.ch/twiki/bin/view/cmspublic/physicsresultsexo 6

27 CMS-PAS-EXO CMS Preliminary -.7 fb ~ ~ Long-lived t t llbb reinterpretation of (3 TeV) scalar LQ LQ µµjj (CMS EXO-6-007) ) [cm] ~ t cτ( Expected 95% CL upper limit Observed 95% CL upper limit CMS EXO-6-0 Observed limit M ~ [GeV] t Example of reinterpretaeon in CMS: constraints on long-lived stop pair produceon from a lepto-quark analysis 7