LHC: HUNT FOR DARK MATTER

Transcription

1 Sean Connery as Marko Ramius LHC: HUNT FOR DARK MATTER Teruki Kamon 1),2) 1) Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University 2) WCU Collider Physics Research, Kyungpook National University Colloquium, Korea Institute for Advanced Study (KIAS), Korea November 25, OUTLINE Summary 3 1) Dark Matter and SUSY 2) LHC & CMS Detector 3) Re-discoveries SUSY Prologue The LHC started taking data from proton-proton collisions at a center-of-mass energy of 7 TeV on March 30, 2010 and became the energy frontier machine to lead to discoveries of new particles. The Standard Model (SM) is currently well tested up to ~100 GeV, but is expected to break down in the TeV domain where new physics should occur. This is precisely the domain that we will study at the LHC. Teruki Kamon New Physics at CMS 2

2 TAMU-KNU Pheno Projects We have been working on how to determine cosmologically-consistent collider signals. Below are the list of papers. Phys. Lett. B 505 (2001) 161 Phys. Lett. B 538 (2002) 121 Phys. Lett. B 611 (2005) 223 Phys. Lett. B 618 (2005) 182 Eur. Phys. J. C46 (2006) 43 Phys. Lett. B 639 (2006) 46 Phys. Lett. B 649 (2007) 73 Phys. Rev. Lett. 100 (2008) Phys. Rev. D 79 (2009) hep-ph/ , accepted for publication in Phys. Rev. D (2010) Today, I focus on theoretical motivation to search for SUSY dark matter and show a experimental readiness of the CMS detector for 2011 run. 3 Dark Matter in the Universe splitting normal matter and dark matter apart Another Clear Evidence of Dark Matter Ordinary Matter (8/21/06) (NASA s Chandra X Observatory) time Dark Matter (Gravitational Lensing) Approximately the same size as the Milky Way Teruki Kamon PPC at the LHC 4 4

3 The Universe Do we know the content of the universe? Wilkinson Microwave Anisotropy Probe (WMAP) : DM = 23% What is the dark matter? An elementary particle? Teruki Kamon PPC at the LHC 5 Properties of Cold Dark Matter 4 It Doesn t Matter. Right, it doesn t shake hand with anyone easily. Two dark matter clusters (in blue) are just passing each other. It is a long-lived (stable) object. It s a Cold Matter. Yes, it is a relativistically slowly moving ( cold ) object. It s an Invisible Matter. Right, it doesn t respond to your flash light. This means it is a neutral object. So, It s a (CDM). Can it be one of the known particles? Let s check out! Teruki Kamon PPC at the LHC 6

4 CDM in The Standard Model? Quarks, electron, muon, tau particles, and force carriers can not be the dark matter, since their interactions are stronger than what we expect. Neutrinos can, but they have other problems. X X X X XXX XXX XXX XXX We need an new idea beyond the Standard Model. Any guidance? e.g., Supersymmetry (SUSY) Teruki Kamon PPC at the LHC 7 Dark Matter Sandwich I am hungry. Can you make the DM sandwich with any Standard Model particle? No, Sir. But with neutralino? MENU ~SPECIALS~ *Dark Energy Power Drink.. $73 - Chef s choice *Dark Matter Sandwich $23 - Neutral, long-lived *Atomic Soup. $4 - All elements in one Teruki Kamon Probing Supersymmetric Connection with DM 8

5 Texas-style SUSY Hunting S. Kamon Teruki Kamon PPC at the LHC 9 Supersymmetry (SUSY) SUSY is : a) Supersymmetrized Standard Model ( Democratic solution between Fermions and Bosons); + b) An elegant solution to solve the problem associated with the Higgs mass; Unification! c) Beautifully connecting the Standard Model with an ultimate unification of the fundamental interactions; d) Cosmologically consistent with a Dark Matter candidate stable neutralino. SUSY Particle type ~ 0 1 Neutral Lightest Teruki Kamon PPC at the LHC 10

6 Probing Early Universe LHC annihilation combination 11 I am traveling a lot 0 1 Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University

7 My Daughter s Image of Dad S. Kamon WORLD PHYSICS AGENCY WPA Code: XXXX XXXX XXXX 0007 (Dark Matter Hunter) Code Name: SUSY Affiliations: TAMU, KNU Occupation: Professor Current Status: ACTIVE, Traveling Country: Europe, Japan, Korea, USA DOB: unknown Location: unknown High Energy Physics Special Agent TERUKI KAMON I always have to carry on Japanese passport, US residency card, Texas A&M faculty ID card, Texas state drivers license card, and Korean residency card. 13 Large Hadron Collider (LHC) 27 km ring 14

8 The LHC is : Accelerator to provide 7-TeV (*) proton beams from a H bottle; Big (27 km circumference); Cool (1.9K using 60 tons of Liquid Helium); Hot (synchrotron radiation, in media); Enormous and very sophisticated magnetic system; Powerful (14 TeV (*) collisions, Total magnetic energy stored is that of Aerobus A380 flying at 700 km/h). (*) 3.5 TeV/beam in 2010 Teruki Kamon PPC at the LHC 15 Powerful to Create Massive Objects Teruki Kamon PPC at the LHC 16

9 Discovery Path at the LHC 14,000 x mass of proton (14 TeV) = Collision Energy Protons fly at % of speed of light 2808 = Bunches/Beam 100 billion (10 11 ) = Protons/Bunch 7.5 m (25 ns) 14 TeV Proton-Proton Collisions Bunch Crossing 40 million (10 6 ) Hz Proton Collisions 1 billion (10 9 ) Hz Parton Collisions New Particles 1 Hz to 10 micro (10-5 ) Hz (Higgs, SUSY,...) Cosmologically Consistent Signals One discovery event in 10,000,000,000, trillion collisions Teruki Kamon PPC at the LHC 17 Discoveries with Missing ET Standard Model s CV 1973 B.S. Neutral CERN SPS (400 GeV p) 1983 M.S. W/Z discovery W CERN SppS (540 GeV pp ) 1995 Ph.D. Top discovery t W Fermilab Tevatron (1.8 TeV pp ) 20?? Evidence of SUSY-like new physics in the jets + MET final state at the LHC Missing E T (MET) - inferring neutrinos MET - inferring new physics (if the dark matter is like a heavy neutrino.) Cosmology LHC = [Exciting Motivation][Right Place&Timing] Teruki Kamon PPC at the LHC 18

10 b [Ref.] Missing E T b e p visible b p 0 p e detected p b p p slash Experimentally, we measure a momentum imbalance in transverse plane and call it missing miss transverse energy ( or E ). E T Teruki Kamon PPC at the LHC 19 T Compact Muon Solenoid Hubble Space Telescope The CMS (21 m x 15 m x 15 m, 12,500 tonnes) is one of two super-fast & super-sensitive detectors, consisting of 15 heavy elements, collecting debris from the collision and converting a visual image for us. Particle Telescope at CERN vs. Hubble Space Telescope in outer space Teruki Kamon 20

11 : First LHC Beam 21 LHC is Back! (Nov. 23, 2009) : 900 GeV CMS CMS 19:20 pm p p CMS 17:59 pm LHCb LHCb 14:22 pm ATLAS ATLAS ALICE 2.36 TeV 12/06/ TeV 3/30/ TeV in ? Teruki Kamon 22

12 Re-Discoveries K s M=497.7 MeV/c 2 =7.6 MeV/c 2 p M=1.116 GeV/c 2 =3.1 MeV/c 2 KK Charged Particle Multiplicity JHEP 02 (2010) LHC is back! & We are ready!! Teruki Kamon : 7 TeV 7:15 7:46 7:46 7:50 9:11 10:08 10: GeV Sunghyun Chang 3500 GeV 12:33 12:46 12:48 Beam1(c.w.) Beam2(c.c.w.) 12:58 Teruki Kamon 24

13 2010 Run (Mar 30 ~ Oct 29) Teruki Kamon 25 SUSY Searches at CMS It is critical to understand the SM production (e.g., W, Z, top), since they are often dominant backgrounds for new particle searches. I will go through selected topics on the SM analyses and new particle searches: 1) Dilepton resonances; W and Z bosons 2) Top quark ) We have to understand jets see an example in Search for new quark-like or gluon-like particle: X jj 4) We have to understand MET. 5) Remark on particle physics and cosmology Teruki Kamon 26

14 : First 1 pb J nb Z pb -1 (~80 x 10 9 pp collisions) LHC is powerful enough to re-discover those particles in ~4 months. Teruki Kamon 27 W and Z bosons Teruki Kamon 28

15 [ W ] [ Z] p p T T W and Z in Channel 9 GeV ( 2.1) 20 GeV ( 2.4) 1.1 pb -1 Simultaneous fits to backgrounds and signal contributions. QCD background shapes obtained using data. Electroweak background shapes and signal from MC. Teruki Kamon 29 [ W & Z] p T ( , ) W and Z in e Channel 20 GeV 1.1 pb -1 W: 75% efficiency Z: 90% efficiency QCD background shapes from data Electroweak background and signal shapes from MC Teruki Kamon 30

16 W and Z: Results 2.9 pb -1 ATLAS arxiv: pb W s, 179 Z/* s / ~ 5% CMS Soon 2.9 pb -1 Teruki Kamon 31 W and Z: toward Results with 35 pb -1 Teruki Kamon 32

17 Top Precise SM measurements Great tool to calibrate detector (e.g., jet energy scale, b- tagging efficiency) Top is one of dominant BGs in many new physics scenarios (e.g., SUSY). A window to new physics Teruki Kamon 33 Top Dilepton: Event Display μμ +bb + MET Candidate Event E T b 2 b 1 b 1 b 2 j y [cm] z [cm] j Very clean candidate sitting in a region where we expect very little background! Teruki Kamon 34

18 Top Dilepton: Results arxiv: , submitted to PLB Full selection applied: Z-boson Veto, M()-M(Z) > 15 GeV MET>30 (20) GeV in ee,, (e ) ; N(jets) T > 30 GeV) 11 tt _ w/o N(jets) candidates (3e, 3ee, 5) over a negligible background 3.1 pb -1 Teruki Kamon 35 Top Dilepton: Results 3.1 pb -1 Testing with KINematic (KIN) method and Matrix-element Weighting Technique (MWT) Consistent with top pair-production (M top = GeV) Mass measurement with ~40 pb -1 in lepton+jets+met. Teruki Kamon 36

19 Top Dilepton: Results 3.1 pb -1 ATLAS??? CMS (PLB) 3.1 pb -1 / ~ 15% Teruki Kamon 37 Top Lepton+Jets: Event Display e + jj + bb + MET Candidate Event Event passes all cuts: 1 high-momentum electron significant MET GeV 4 high-p T jets, two of which with good/clear b-tags E T b 2 j 2 j 1 b 2 e j 1 b 1 e m T (W) 2 m(jj) 102 GeV/c 2 m(jjj) 208, 232 GeV/c 2 (for the two 3-jet combinations) Teruki Kamon 38 b 1

20 Top Lepton + jj + bb + MET: Results 0.84 pb -1 Requiring at least 1 jet b-tagged secondary vertex tagger with high efficiency with ~1% fake rate N(jets) 3: Observed: 30 e / candidates Predicted background: N(BG,MC) = 5.3 _ Predicted signal: N(tt,MC) = 15 _ Seeing tt events at a rate roughly consistent with NLO cross section, considering experimental (jet energy scale, b-tagging) and theoretical (scale, PDF, ) uncertainties Aggressively preparing the paper! With ~35 pb-1 Teruki Kamon 39 X jj PRL 105 (2010) or arxiv: Dijet mass differential cross section - sensitive to the coupling of any new massive object (narrow resonance) to quarks and gluons. 2.9 pb -1 [Selection] 1,2 < 2.5 and 12 < 1.3 Teruki Kamon 40

21 X jj Model 2.9 pb -1 CMS (2.9 pb -1 ) CDF (1.13 fb -1 ) String q* Axigluon /Coloron Scalar E 6 Diquark Randall-Sundrum (RS) Graviton (G) MORE W DATA Z ATLAS PRL 105 (2010) ; arxiv: ATLAS-CONF pb -1 q* : TeV 3.1 pb -1 q* : TeV Teruki Kamon 41 SUSY Reference Analyses RA1.. Jets.. T RA2.. Jets + MET RA3.. Photon + jets + MET RA4.. Lepton + jets + MET RA5.. OS Dilepton + jets +MET RA6.. LS Dilepton + jets + MET RA7.. Trilepton Teruki Kamon 42

22 Example: RA1 SUS RA1.. T = E T2 /M T(jj) Just using jet topology, avoiding from a direct use of MET. We want to understand MET No QCD! New Physics, here Aggressively preparing the paper with ~35 pb -1 Teruki Kamon 43 u (Absolute) MET Scale / q T ( ) for events with photon p T > 20 GeV 3 different algorithms Type II CaloMET TC MET PF MET Data/MC q T ( ) JME (0.2 pb -1 ) [Goal] Improve a linearity of MET (5% 3% with 35 pb -1 ). The MET scale is insensitive to N PV (JME ). We also need to study with + 3jet events for SUSY-like topology. 44

23 Illustrating CMS Amusement JME MET from W (scaled) ~20 x 10 6 MB 70 mb, corresponding to L MB dt ~0.3 nb -1 (We,, ) ~ 30 nb N EWK = 30 nb x 0.3 nb -1 = 9 events ~0.5 events per 1-GeV bin in the figure, assuming a flat distribution between 25 and 45 GeV. 0.5 events PF MET [GeV] In CDF and D0, we haven t seen the MET distribution closer to a level of Electroweak physics. With ~35 pb -1, we are seeing more rare noses. Further improvements are being made. 45 Example: RA2 Prospects 46

24 Warning! Events/50 GeV/100 pb M eff ( E T ET,i )[GeV] i Background SUSY 600 GeV q ~ An Excess Not Good Enough Teruki Kamon PPC at the LHC ) An inclusive search in Jets + MET using m T2 arxiv: v1 Alan J. Barr and Claire Gwenlan tt QCD Z 2) If we see an excess, we could estimate a mass of the dark matter particle assuming this is SUSY. Teruki Kamon PPC at the LHC 48

25 1) 1 B s 2) 2 Inclusive m T2 3) 3 MET + jets + X WCU Projects Rouzbeh Allahverdi, Bhaskar Dutta, Yudi Santoso arxiv: CDMS II Excluded by 1) a Rare B decay b s 2) b No CDM candidate 3) c Muon magnetic moment Teruki Kamon PPC at the LHC 49 LHC 2011 Roger Bailey s talk at LHCC (Nov 12, 2010) Beam back around 21 st February 2 weeks re-commissioning with beam (at least) 4 day technical stop every 6 weeks Count 1 day to recover from TS (optimistic) 2 days machine development every 2 weeks or so 4 days ions set-up 4 weeks ion run End of run 12 th December ~200 days proton physics LHC status 50

26 2011: Reasonable & Ultimate Numbers 4 TeV (*) 936 bunches (75 ns) 3 micron emittance 1.2 x protons/bunch * = 2.5 m, nominal crossing angle (*) to be discussed at Chamonix) Peak luminosity 6.4 x Integrated per day 11 pb days 2.2 fb -1 Stored energy 72 MJ 4 TeV 1400 bunches (50 ns) 2.5 micron emittance 1.5 x protons/bunch * = 2.0 m, nominal crossing angle Peak luminosity 2.2 x Integrated per day 38 pb days 7.6 fb -1 Stored energy 134 MJ Usual warnings apply see problems, problems above 12/11/10 LHC status 51 Example of Impact on LHC Physics Consistent with SUSY 7 TeV 7 TeV 8 TeV Teruki Kamon 52

27 Tevatron to LHC remark refcolliders/lhc/ Teruki Kamon PPC at the LHC 53 CBS comedy Big Bang Theory (Season 1 Episode 15) 54

28 Summary Remark: PPC Interconnection between Particle Physics and Cosmology PPC 2011 at CERN, June PPC 2012 at??? Teruki Kamon 55 Summary CSI: Supersymmetry at the LHC Collider Scene Investigation LHC keep going! Teruki Kamon 56

29 FYI: ZZ Candidate 57 FYI: Heavy Ion Collision Nov. 8, 2010 Pb-Pb collision 2.76 TeV/nucleon pair (RHIC x 14) 58

30 FYI: Z in Heavy Ion Collision Nov. 14,