0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN 16th - PowerPoint PPT Presentation

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN 16th March 2016 Moriond EW 1 / 63

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN Introduction ◮ Supersymmetry is one of the most favoured extensions of the Standard Model (SM) of particle physics. ◮ It postulates the existance of partner particles for all the SM particles. ◮ There have been many searches for such particles and here I will cover the latest results from ATLAS and CMS in channels without leptons. ◮ These are some of the most sensitive channels for many supersymmetric models as seen from the parameter scans performed after Run I [1][2]. ◮ ATLAS has produced 3 separate results for 3 different signatures; 1. 0-lep. + ≥ 2-6 jets + E miss [ATLAS-CONF-2015-062] T 2. 0-lep. + ≥ 7-10 jets + E miss [1602.06194] T 3. 0/1-lep. + ≥ 3-b-jets + E miss [ATLAS-CONF-2015-067] T ◮ CMS have produced 4 separate results utilizing different approaches; 1. H T and H miss search [1602.06581] T 2. M T2 based search [1603.04053] 3. α T based search [CMS-PAS-SUS-15-005] 4. Razor variables based search [CMS-PAS-SUS-15-004] 2 / 63

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN Contents ◮ As the ATLAS and CMS analyses are similar in nature and look for similar models I will go through them in parallel; 1. The signatures that we search for 2. Variables used to define signal regions 3. Estimating the W and t ¯ t backgrounds 4. Estimating the Z → νν background 5. Estimating the Multi-jet background 6. Estimating the background in the Razor analysis 7. Results and Statistical interpretation 8. Limits on models 3 / 63

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN The Signatures We Search For ◮ The focus at the start of Run I has been searches for gluino production in R-parity conserving models due to the large x-section increase. ◮ The lightest supersymmetric particle is neutral and passes through the detector undetected in these models → E miss . T ◮ The searches are all therefore characterised by jets + E miss . T Main background Signal 4 / 63

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN Variables used to define signal regions (ATLAS) The ATLAS ≥ 2-6 jets and ≥ 3-b-jet analyses are both largely based around the variable; m eff = E miss � p jet + T T and also use cuts on ∆ φ ( jet , E miss ) to reduce the multi-jet background. T They also use m min ( b - jets , E miss g → t ¯ χ 0 For ˜ t ˜ 1 , ≥ 3-b-jets also cuts on the ) which T T has an end-point for semi-lep. t ¯ number of high mass large radius jets. t . 6 5 10 10 Events Events / 25 GeV Data 2015 Data 2015 ATLAS Preliminary ATLAS Preliminary Total background Total background 5 s = 13 TeV, 3.3 fb -1 s = 13 TeV, 3.3 fb -1 10 t t 4 t t 10 Gtt 0-lepton pre-selection Single top Gtt 0-lepton pre-selection Single top t t + W/Z/h t t + W/Z/h σ × σ × 10 4 Gtt: m , m = 1600, 200 ( 100) Gtt: m , m = 1600, 200 ( 100) ~ g χ ∼ 0 Z+jets g ~ χ ∼ 0 Z+jets 3 1 10 1 Gtt: m , m = 1400, 800 ( σ × 100) W+jets Gtt: m , m = 1400, 800 ( σ × 100) W+jets ~ ∼ 0 ~ ∼ 0 g χ g χ 1 Diboson 1 Diboson 3 10 10 2 2 10 10 10 1 1 2 2 Data / SM Data / SM 1 1 0 0 0 1 2 3 4 0 50 100 150 200 250 300 350 400 miss Number of top-tagged jets m min (b-jets,E ) [GeV] T T The ATLAS ≥ 7-10 jet search counts the number of jets p T > 50 , 80 GeV with | η | < 2, √ H T > 4 GeV 1 / 2 motivated by the bins in the number of b -jets, and requires E miss / T 5 / 63 multijet background estimation (see later).

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN ATLAS Signal Regions (for reference) The 7 ≥ 2-6 jet search signal regions: Signal Region Requirement 2jl 2jm 2jt 4jt 5j 6jm 6jt E miss [GeV] > 200 T p T ( j 1 ) [GeV] > 200 300 200 p T ( j 2 ) [GeV] > 200 50 200 100 p T ( j 3 ) [GeV] > – 100 p T ( j 4 ) [GeV] > – 100 p T ( j 5 ) [GeV] > – 100 p T ( j 6 ) [GeV] > – 100 ∆ φ (jet 1 , 2 , (3) , E miss ) min > 0.8 0.4 0.8 0.4 T ∆ φ (jet i> 3 , E miss ) min > – 0.2 T E miss / √ H T [GeV 1 / 2 ] > 15 20 – T Aplanarity > – 0.04 E miss /m eff ( N j ) > – 0.2 0.25 0.2 T m eff (incl . ) [GeV] > 1200 1600 2000 2200 1600 1600 2000 The 15 ≥ 7-10 jet search signal regions: 8j50 8j50-1b 8j50-2b 9j50 9j50-1b 9j50-2b 10j50 10j50-1b 10j50-2b n 50 ≥ 8 ≥ 9 ≥ 10 n b − jet — ≥ 1 ≥ 2 — ≥ 1 ≥ 2 — ≥ 1 ≥ 2 / √ H T E miss > 4 GeV 1 / 2 T 7j80 7j80-1b 7j80-2b 8j80 8j80-1b 8j80-2b n 80 ≥ 7 ≥ 8 n b − jet — ≥ 1 ≥ 2 — ≥ 1 ≥ 2 / √ H T E miss > 4 GeV 1 / 2 6 / 63 T

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN ATLAS Signal Regions (for reference) g → b ¯ χ 0 g → t ¯ χ 0 The 3 ˜ b ˜ 1 and 3 ˜ t ˜ 1 , ≥ 3-b-jet search signal regions (1-lepton regions are also used in this analysis): Criteria common to all Gtt 0-lepton regions: p Tjet > 30 GeV Variable Signal region Control region VR1L VR0L Lepton 0 signal = 1 signal = 1 signal 0 signal Criteria common to all Gbb regions: ≥ 4 signal jets, ≥ 3 b -jets ∆ φ 4j > 0 . 4 > 0 . 4 − − Criteria common min Variable Signal region Control region Validation region to all regions of the N jet ≥ 8 ≥ 7 ≥ 7 ≥ 8 same type Lepton Candidate veto = 1 signal Candidate veto m b − jets > 80 > 80 < 80 − T , min ∆ φ 4j > 0 . 4 − > 0 . 4 m T − < 150 < 150 − Criteria common min to all regions of the m b − jets − − < 160 E miss T , min > 400 > 250 > 250 > 200 T same type < 150 m T − − m incl > 1700 > 1350 > 1350 > 1400 Region A eff (Large mass splitting) p Tjet > 90 > 90 > 90 N b − jet ≥ 3 ≥ 3 ≥ 3 ≥ 2 Region A E miss > 350 > 250 > 250 N top ≥ 1 ≥ 1 ≥ 1 ≥ 1 (Large mass splitting) T m 4j > 1600 > 1200 < 1400 E miss eff > 350 > 200 > 200 > 200 T p Tjet > 90 > 90 > 90 m incl > 1250 > 1000 > 1000 > 1100 Region B eff Region B (Moderate mass splitting) E miss > 450 > 300 > 300 N b − jet ≥ 4 ≥ 4 ≥ 4 ≥ 3 (Moderate mass splitting) T m 4j > 1400 > 1000 < 1400 N top ≥ 1 ≥ 1 ≥ 1 ≥ 1 eff p Tjet > 30 > 30 > 30 E miss > 350 > 200 > 200 > 200 T Region C Region C E miss m incl > 500 > 400 > 400 > 1250 > 1000 > 1000 > 1250 (Small mass splitting) (Small mass splitting) T eff m 4j > 1400 > 1200 < 1400 N b − jet ≥ 4 ≥ 4 ≥ 4 ≥ 3 eff 7 / 63

0-lep. SUSY Searches from ATLAS and CMS Chris Young, CERN ATLAS Signal Regions (for reference) g → b ¯ χ 0 g → t ¯ χ 0 The 3 ˜ b ˜ 1 and 3 ˜ t ˜ 1 , ≥ 3-b-jet search signal regions (1-lepton regions are also used in this analysis): Criteria common to all Gtt 0-lepton regions: p Tjet > 30 GeV Variable Signal region Control region VR1L VR0L Lepton 0 signal = 1 signal = 1 signal 0 signal Criteria common to all Gtt 1-lepton regions: ≥ 1 signal lepton, p Tjet > 30 GeV Criteria common to all Gbb regions: ≥ 4 signal jets, ≥ 3 b -jets ∆ φ 4j > 0 . 4 > 0 . 4 − − Criteria common min Variable Signal region Control region Validation region VR-m b − jets Variable Signal region Control region to all regions of the VR- m T N jet ≥ 8 ≥ 7 ≥ 7 ≥ 8 T , min same type Lepton Candidate veto = 1 signal Candidate veto m b − jets > 80 > 80 < 80 − > 150 < 150 > 150 T , min < 150 m T Criteria common ∆ φ 4j > 0 . 4 − > 0 . 4 m T − < 150 < 150 − Criteria common min to all regions of the N jet ≥ 6 ≥ 6 ≥ 5 ≥ 6 to all regions of the m b − jets − − < 160 E miss T , min same type > 400 > 250 > 250 > 200 T same type N b − jet < 150 ≥ 3 ≥ 3 = 3 = 3 m T − − m incl > 1700 > 1350 > 1350 > 1400 Region A eff (Large mass splitting) p Tjet > 90 > 90 > 90 N b − jet E miss > 200 > 200 > 200 > 200 ≥ 3 ≥ 3 ≥ 3 ≥ 2 Region A T E miss > 350 Region A > 250 > 250 N top ≥ 1 ≥ 1 ≥ 1 ≥ 1 (Large mass splitting) T m incl > 1100 > 1100 > 600 > 600 m 4j eff > 1600 (Large mass > 1200 < 1400 E miss eff > 350 > 200 > 200 > 200 m b − jets T splitting) > 160 − < 160 > 140 T , min p Tjet > 90 > 90 > 90 m incl > 1250 > 1000 > 1000 > 1100 Region B eff Region B N top ≥ 1 (Moderate mass splitting) ≥ 1 ≥ 1 ≥ 1 E miss > 450 > 300 > 300 N b − jet ≥ 4 ≥ 4 ≥ 4 ≥ 3 (Moderate mass splitting) T m 4j > 1400 > 1000 < 1400 N top ≥ 1 ≥ 1 ≥ 1 ≥ 1 E miss > 300 > 300 > 200 > 200 eff Region B T p Tjet > 30 > 30 > 30 E miss > 350 > 200 > 200 > 200 (Moderate to small m incl > 900 > 900 > 600 T > 600 Region C eff Region C E miss mass splitting) m incl > 500 > 400 > 400 > 1250 > 1000 > 1000 > 1250 (Small mass splitting) (Small mass splitting) T m b − jets eff > 160 − < 160 > 160 m 4j T , min > 1400 > 1200 < 1400 N b − jet ≥ 4 ≥ 4 ≥ 4 ≥ 3 eff 8 / 63