ATLAS/CMS Upgrades. Yasuyuki Horii Nagoya University on Behalf of the ATLAS and CMS Collaborations

Transcription

1 ATLAS/CMS Upgrades Yasuyuki Horii Nagoya University on Behalf of the ATLAS and CMS Collaborations

2 Outline 2/26 LHC/HL-LHC plan ATLAS/CMS upgrades Physics prospects

3 LHC/HL-LHC Plan

4 Overview 4/26 SM precision studies and BSM searches with 134 TeV and 3000 fb. Peak instantaneous luminosity: 5-7x 34 cm -2 s a lot of challenges. Two upgrade phases: Phase 1 ( ) and Phase 2 ( ).

5 Luminosity levelling 5/26 The average luminosity is almost the same. HL-LHC is designed to operate with levelling. Lower pileup in the experimental detectors Lower energy deposition by the collisions in the interaction region magnets CERN-ACC

6 ATLAS/CMS Upgrades

7 Challenges 7/26 Increased luminosity provides a significant challenge for the experiments. Upgrades are essential to exploit the full potential of LHC and HL-LHC. Higher radiation dose Higher pileup Higher particle rate Higher event rate Replacement of some of the detectors Replacement of the electronics Overall modifications on the trigger and readout scheme

8 Inner tracker ATLAS CMS 8/26 Inner trackers will be in an extreme environment at HL-LHC. 1 MeV neutron equivalent fluence up to 2 x 16 /cm 2. Ionisation dose up to MGy. Particle rates up to 2 GHz/cm 2 high occupancy, high bandwidth. CMS Pileup 140 expected at L = 5 x 34 cm -2 s CERN-LHCC ; LHCC-P-008

9 Inner tracker ATLAS Phase 2 9/26 Entire tracker replacement (all-silicon tracker) at the Phase 2 upgrade. Radiation tolerance, increased granularity, reduced material, extension to forward, Ratio of reconstructed to generated tracks No pileup dependence with 11 hits Channel occupancy [%] for 200 pileups Pixel thickness possibly 150 µm, pixel size possibly 50 x 50 µm 2 CERN-LHCC ; LHCC-I-023. CERN-LHCC ; LHCC-G66.

10 Inner tracker CMS Phase 1/2 /26 Pixel detector replacement in the end of 2016 (as a Phase 1 project). Entire tracker replacement at the Phase 2 upgrade. Strip Pixel +Strip Pixel Pixel size considered: 25x0 µm 2 and 50x50 µm 2 Radiation tolerance, increased granularity, reduced material, extension to forward, CERN-LHCC ; LHCC-P-008

11 Calorimeter CMS Phase 2 11/26 Endcap calorimeter will be replaced longevity and performance issues. Hadron fluence 2 x 14 /cm 2 at η = 2.6. Defects in lead tungstate scintillating crystal of the electromagnetic calorimeter. A high-granularity sampling calorimeter with a tungsten/silicon electromagnetic part (EE) followed by brass/silicon (FH) and brass/scintillator (BH) hadronic parts. Fraction of the response Light transmission loss Response degradation also expected for the hadron calorimeter. High performance at high pileup CERN-LHCC ; LHCC-P-008

12 Muon spectrometer ATLAS Phase 1 12/26 New Small Wheel will be installed to cope with a relatively high hit rate (~15 khz/cm 2 at L = 7 x 34 cm -2 s ) and also to improve muon trigger. Both MM and stgc for precision tracking and trigger. Position resolution per layer: ~0 µm. Segment angle resolution at first-level trigger: ~1 mrad. Coverage: 1.3 < η < 2.7. Micro-mesh gaseous detector (MM) CERN-LHCC ; ATLAS-TDR-020

13 Trigger ATLAS CMS 13/26 More luminosity more interesting events but also more background. Without changes, trigger rates exceed the limits of trigger/readout system. Choice of ATLAS and CMS at Phase 2 upgrades Increase trigger rates. First level: ~0 khz khz Storage level: ~1 khz 5- khz Increase latency improve algorithm. First level: ~3 µs 62.5 µs Simply increasing the threshold would kill the signal. Electronics replacements for all sub-systems. CERN-LHCC ; LHCC-I-023. CERN-LHCC ; LHCC-G65. CERN-LHCC ; LHCC-G66.

14 Trigger CMS Phase 2 14/26 Track trigger implementation in the first-level trigger. Benefits: improved pt determination, better identification of charged leptons, Technologies: studies ongoing for Associative Memories, FPGA, Electron trigger Muon trigger CERN-LHCC ; LHCC-P-008.

15 Trigger ATLAS 15/26 Calorimeter trigger upgrade Higher granularity information provided at first-level trigger. Less sensitive to pileup. Current Muon trigger upgrade Extend muon trigger acceptance in the barrel by additional chambers. Phase 2 Additional RPCs Phase 1 Muon A x ε in barrel could be improved from ~70% to ~95%. Trigger rate reduction for e, γ, CERN-LHCC ; ATLAS-TDR O. Kortner, VCI 2016.

16 Physics Prospects Examples

17 tth 17/26 Direct probe of Higgs-top coupling. Events / ( 2 GeV ) ATLAS Simulation Preliminary L dt = 3000 fb, Simulation Background Fit s=14 TeV Background subtracted events Signal Fit gg H and H γγ indirect (loops). m γ γ [GeV] Observation expected for tth, H γγ. ATLAS expected: 8.2σ (3000 fb ). ATL-PHYS-PUB

18 H bb 18/26 Access to Higgs-bottom coupling. Events / 20 GeV ATLAS Simulation Preliminary s = 14 TeV, 3000 fb, <µ> = lep, 2 jets, 2 tags, p Z > 200 GeV T ZH x Diboson tt Z+bb Z+bl Z+cc Z+cl Z+l Unc. Events / 20 GeV ATLAS Simulation Preliminary s = 14 TeV L dt = 3000 fb <µ> = 140 V 1 lep., 2 jets, p > 200 GeV T VH(bb)x VZ WW Multijet tt t, s+t-chan Wt W+bb W+bl W+cc W+cl W+l Z+bb Unc m bb [GeV] m bb [GeV] Observation expected for VH, H bb (V = Z or W). ATLAS expected significance at 3000 (300) fb : 8.8σ (3.9σ). ATL-PHYS-PUB

19 H µµ 19/26 Access to Higgs-muon coupling. Events / 0.5 GeV ATLAS Simulation Preliminary s = 14 TeV L dt = 3000 fb H µµ, m =125 GeV H Z µµ tt WW µνµν m µµ [GeV] (Data - Background) / 0.5 GeV ATLAS Simulation Preliminary s = 14 TeV L dt = 3000 fb S+B toy Monte Carlo S+B model B-only model m µµ [GeV] Reduction of the material and better spacial resolution for tracking at Phase 2. Mass resolution expected: 40% better with respect to Phase 1 aged (radiation damage for 00 fb assumed). Observation expected for H µµ. ATLAS expected: 7.0σ (3000 fb ). CERN-LHCC ; LHCC-P-008. ATL-PHYS-PUB

20 Higgs couplings 20/26 ATLAS Simulation Preliminary s = 14 TeV: κ gz λ WZ λ tg λ bz Ldt=300 fb ; Ldt=3000 fb Fit with a fully generic parametrisation No assumption on the total width κgz (= κgκz/κh) overall scale parameter common to all signal channels No assumption on new particle contribution through loops λ τz λ µz Hashed areas: current theory systematic uncertainties λ gz λ γz λ (Zγ)Z For various coupling scale factor ratios, the precision of % level expected at 3000 fb κ λ XY = ( κ X ) Y Similar precision expected for ATLAS and CMS. ATL-PHYS-PUB arxiv: [hep-ph].

21 Higgs couplings 21/26 1/2 or (g/2v) λ 1 CMS Projection 68% CL 3000 fb (14 TeV) W Z t -2 τ b -3 µ mass (GeV) Significant improvement expected with 14 TeV, 3000 fb. Precision test of Yukawa terms for various flavors : t, b, τ, and µ. -4 CERN-LHCC ; LHCC-G65

22 Bs,d µµ 22/26 Bs,d µµ decays are only proceed through FCNC processes and are highly suppressed in SM. C. Bobeth, et al., PRL 112, 1801 (2014) B (Bs µµ) = (3.65 ± 0.23) x -9 B (Bd µµ) = (1.06 ± 0.09) x - CMS and LHCb, Nature 522, 68 (2015) B (Bs µµ) = ( ) x -9 B (Bd µµ) = ( ) x - ATLAS, arxiv: [hep-ex] B (Bs µµ) = ( ) x -9 B (Bd µµ) < 4.2 x - (95% CL) Some of new physics scenarios D. M. Straub, arxiv: may boost the Bs,d µµ decay rates. Bs/Bd ratio provides a stringent test of various models beyond SM.

23 Bs,d µµ 23/ fb 3000 fb S/(S+B) Weighted Events / ( 0.02 GeV) CMS Simulation Scaled to L = 300 fb η(µ) <1.4 data full PDF - B s µ + µ - B d µ + µ combinatorial bkg semileptonic bkg peaking bkg S/(S+B) Weighted Events / ( 0.01 GeV) CMS Simulation Scaled to L = 3000 fb η(µ) <1.4 data full PDF - B s µ + µ - B d µ + µ combinatorial bkg semileptonic bkg peaking bkg m µµ (GeV) B (Bs µµ) precision: 13% B (Bd µµ) precision: 48% (2.2σ) m µµ (GeV) B (Bs µµ) precision: 11% B (Bd µµ) precision: 18% (6.8σ) σ x B predicted by SM assumed. CERN-LHCC ; LHCC-P-008. K. F. Chen, EPS-HEP 2015.

24 Bs J/ψφ 24/26 CP violation due to interference between direct decay and decay with Bs-Bs mixing. _ 0 0 _ 0 Bs 0 Bs J/ψφ New physics can show up in the mixing. Phase difference between interfering amplitudes φs extracted from decay time defined on the transverse plane:. Improve decay time resolution στ by 30% with respect to Run 1 at ATLAS. Luminosity 250 fb 3000 fb σ(φs) (Stat.) rad rad Method improvement in arxiv: [hep-ex]. ) [ps] 0 s σ τ (B Run 2, ATLAS 2012 <µ> = 20 IBL Layout, <µ> = 60 ITK Layout, <µ> = 200 ATLAS simulation Preliminary Run φs = p T (B 0 s ) [GeV] SM global fit by CKMfitter rad ATL-PHYS-PUB PRD 91, (2015).

25 t qγ, qz, and qh 25/26 FCNC top quark decays are highly suppressed in SM: B < 3. New physics scenarios may enhance the rate up to B ~ -4. HL-LHC expected limits at 95% CL are B = BR(t qz) 1-2 CDF D0 LEP ATLAS (2 fb ) 95% C.L. EXCLUDED REGIONS CL S 1 L dt = 3 ab, s = 14 TeV Expected, tight jet p T Expected, tight jet p Expected, loose jet p Expected, loose jet p ATLAS Preliminary T T T cuts cuts, conservative bkg cuts cuts, conservative bkg -3 CMS (4.6 fb ) ATLAS preliminary (simulation) extrapolated to 14 TeV: H1 (q=u only) 95% fb (sequential) 3 ab (sequential) 3 ab (discriminant) -3-2 ZEUS (q=u only) 1 BR(t qγ) Br(t ch) (x ) ATL-PHYS-PUB ATLAS-PHYS-PUB CMS PAS FTR3-016.

26 Conclusion 26/26 Aim for SM precision studies and BSM searches with 300 fb (LHC) and 3000 fb (HL-LHC) at ATLAS and CMS. Potential observation of the processes related with flavors : tth, H bb, H µµ, Bd µµ, Potential CP-violation measurement of Bs J/ψφ, Increased luminosity (5-7 x 34 cm -2 s ) provides a significant challenge for the experiments. High radiation dose, pileup, particle rate, and event rate. Overcome the difficulties by the upgrades in various aspects.

27 Backup Slides

28 Calorimeter ATLAS Phase 2 28/26 LAr: radiation hardness Maintain required performance under HL-LHC conditions and therefore do not need replacement with possible exception for FCal. FCal replacement with high-granularity one (0 µm gap) under discussion. Addition of timing detector (intrinsic resolution O() ps) under discussion. CERN-LHCC ; LHCC-G66

29 Calorimeter CMS Phase 2 29/26 Radiation dose at 3000 fb for the scintillating tiles of the endcap hadron calorimeter will reach up to 300 kgy response degradation expected. For the new endcap calorimeter, exploit advances in silicon detectors in terms of cost per unit area and radiation tolerance. The silicon sensors to be used will be simple, large area, and single-sided. CERN-LHCC ; LHCC-P-008

30 Muon spectrometer ATLAS 30/26 Current drift tube chambers: inefficiency and resolution degradation with hit rate above 300 khz/tube. Impact on the endcap inner layer with L > 34 cm -2 s. CERN-LHCC ; ATLAS-TDR-020

31 Muon spectrometer CMS Phase 2 31/26 Possible additional chambers GEM micro-pattern gas amplification detector RPC time resolution of ~0 ps for pileup mitigation (i) new irradiation tests must be performed to confirm that all types of existing muon detectors will survive the harsher conditions. (ii) additional muon detectors in the forward region 1.6 < η < 2.4 to increase redundancy and enhance the trigger and reconstruction capabilities. (iii) extension of muon coverage up to η = 3 or more behind the new endcap calorimeter to take advantage of the pixel tracking coverage extension. CERN-LHCC ; LHCC-P-008

32 Higgs couplings 32/26 i y ATLAS Simulation Preliminary h γ γ, h ZZ* 4l, h WW* lνlν h τ τ, h bb, h µµ, h Zγ [κ Z, κ W, κ t, κ b, κ τ, κ µ ] BR i,u =0 µ b τ s = 14 TeV Z W Ldt = 300 fb Ldt = 3000 fb t Scenario 1: all systematic uncertainties unchanged. Scenario 2: improved theoretical/systematic uncertainties. Ratio to SM [GeV] m i 2 CERN-LHCC ; LHCC-P-008. ATL-PHYS-PUB

33 Bs,d µµ 33/26 Without trigger upgrade, unsustainable event rate at HL-LHC. Track trigger with upgraded CMS detector plays an essential role. Events / (0.02 GeV) 8 CMS Simulation Scaled to L = 3000 fb L1TrkMu (PhaseII) Trigger p (µ) > 3 GeV T η(µ) < 2 p (µµ) > 4 GeV T η(µµ) < 2 d z (µµ) < 1 cm 3.9 < m(µµ) < 6.9 GeV - B s µ + µ - B d µ + µ Background Total signal 2 Invariant mass mµµ resolution at Level trigger expected: ~70 MeV m µµ (GeV) Level trigger rate expected: a few hundred Hz (<< 1 MHz). at Level trigger CERN-LHCC ; LHCC-P-008. K. F. Chen, EPS-HEP 2015.

34 Bs J/ψφ 34/26 Opposite-side tagging studied and calibrated by B ± J/ψK ± (flavor provided by kaon charge). Di-muon trigger with pt > 11 GeV (both muons) assumed at ATLAS at HL-LHC. Systematic error of Run 1 analysis: uncertainties in flavor charge tagging, likelihood fit modelling, trigger efficiency determination, contribution of B J/ψK * decays, inner tracker alignment will benefit from the larger data samples. ) [ps] 0 s σ τ (B Slight στ increase (14%) in Run 2 with number of primary vertices but stable at > 40. Run 1 ATLAS 2012 <µ> = 20 IBL Layout 11,11 <µ> = 60 ITK Layout 11,11 <µ> = 200 ATLAS simulation Preliminary Run 2, Number of reconstructed PV ATL-PHYS-PUB

35 t qh 35/26 Current 95% CL upper limit on the branching ratio at the order of -3. arxiv: v2 [hep-ex]