LHC Results in Majid Hashemi IPM, Tehran Wednesday, 11 th May 2011

Transcription

1 LHC Results in Majid Hashemi IPM, Tehran Wednesday, 11 th May

2 LHC results after a year of successful data taking Majid Hashemi IPM, 18th May

3 30 March 2010: Milestones LHC started 3.5 TeV beams circulations The center of mass energy for the first time in HEP is 7 TeV A success and victory one year after the tunnel incident in 2008

4 7 TeV Collisions in CMS In the same day, 7 TeV collisions were observed in CMS

5 14 October 2010: More on the way Reached the desired luminosity for 2010 : cm -2 sec -1 A total collected data of 2/pb in one day in CMS and ATLAS 4 November 2010: Highest amount of data in one day : 5/pb delivered to CMS and ATLAS in one day 5 November 2010: 46/pb data delivered to detectors CMS certifies 75% of recorded data : 34.7/pb certified data is available for analysis End of TeV proton-proton story 5 November 2010: Circulating lead ions at LHC 7 November 2010: First H.I. collisions seen in CMS

6 At the end of 2010 a total integrated luminosity of 46 pb -1 was delivered to CMS! Total luminosity recorded by CMS in

7 Total luminosity recorded by CMS in 2011 A factor of 5 more data taken in 2011 so far, However the largest fraction of this data just produced in 10 days! 7

8 Physics results So far the CMS has done two main jobs: Testing SM and Setting limits (exclusions) However there are significant achievements in variety of searches, From another point of view there is a high potential to verify Higgs and SUSY and exotic models in this year Although no signal of such phenomena yet! 8

9 arxiv: Test of Standard model, top quark search The ttbar fully leptonic final state is used for the cross section measurement, Number of jets is compared between MC and data Data looks to be more than MC! The measured cross section is The NLO theoretical value is /- 23 pb with m(t)=172.5gev 9

10 arxiv: Test of Standard model, W and Z search Distribution of missing E T and transverse mass in single W events Invariant mass distribution of dielectron and di-muon in single Z events 10

11 arxiv: Test of Standard model, W and Z search (2) Cross section values measured in electronic and muonic final states in W+X events Cross sections in ee and mm final states in Z+X events 11

12 arxiv: Test of Standard model, W and Z search (3) Consistent results between CMS measurements and theoretical calculations 12

13 arxiv: Test of Standard model, Z ττ search Z ττ signal has been searched for, The tautau invariant mass is lower than the Z mass due to neutrinos, The measured cross section is consistent results with Z μμ or ee 13

14 arxiv: Exotic models, black holes Mini black holes? In ADD model of large extra dimensions, a mini-black hole is possible to be produced in p-p collisions, The heavy black hole decays isotropically to high p T objects, Therefore the scalar sum of p T s (S T ) is high This is the main signature of the mini-bh However no signal of BH observed so far. Excluded black hole masses in different scenarios: Below each curve is the excluded area. 14

15 arxiv: Exotic models, W Search for the heavy W : A particle (a copy of the W boson in SM) introduced in extensions of SM like leftright symmetric models and super symmetric GUT, The mass scale is ~1TeV so its transverse mass starts to be distinguishable from SM distributions at high values, No observation of this particle yet! W masses below 1.58 TeV excluded. 15

16 arxiv: Exotic models, Z Di-lepton resonances: The di-lepton resonances could be signatures of Z in sequential SM, Klauza-Klein graviton excitations in Randall-Sundrum model of extra dimensions, or GUT models with super strings, No observation of such particles yet! Again setting 95%C.L. : M(Z SSM )< 1140 GeV M(Z y )< 887 GeV M(G KK )<855(1079) GeV for k/m Pl =0.05(0.1) 16

17 arxiv: Exotic models, di-photons with high invariant masses The ADD model of extra dimensions, may produce di-photon signals via KK graviton states, Coupling to fermions is suppressed due to the spin constraints, No signal has been observed for the set of used parameters in simulations, Effective planck scale lower limit is set in the range of TeV 17

18 arxiv: Heavy Ion collisions, jet quenching Jet quenching indicating features of the hot matter produced in heavy ion collisions: Events of di-jet are selected with Df~p The leading jet is the one closer to the matter boundary The sub-leading jet has lost energy in interactions with the matter particles The energy balance is recovered if p T of particles with p T <2 GeV are integrated over DR<0.8 18

19 arxiv: Heavy Ion collisions, new phenomena re-observation 3 Components: 1)Yellow: Contribution from higher p T clusters i.e. processes like jets, 2)Green: Away-side jets or more generally momentum conservation 3)Red: Lower p T clusters, soft QCD fragmentation New Observation: Intermediate momentum regime Long-range (2<Dh<4), near side(df~0) CMS comment: 19

20 arxiv: arxiv: Heavy Ion collisions, new phenomena Effect already observed in RHIC, PHOBOS detector collaboration PHOBOS comment: 20

21 arxiv: Heavy Ion Collisions, Z peak observation Z μμ candidates were also observaed in Pb-Pb collisions with sqrt(s NN )=2.76 TeV 21

22 arxiv: Search for SUSY, MSSM Higgs decay to di-tau Search for H/h/A ττ in MSSM, No 5s signal yet! Constraints on tanb has been obtained Extending previous experiments results 22

23 arxiv: Search for SUSY, jets and missing E T Susy searches: Pair production of squarks and gluinos are signatures of SUSY in CMS, The heavy squarks and gluinos decay To SM quarks and gluons thus producing high energy jets, They also produce LSP (lightest supersymmetric particle) which produces a significant transverse energy imbalance (MET), No hint of SUSY in two working points of LM0 and LM1 was found But the LEP and TeVatron results were extended sizably! 23

24 arxiv: Search for SUSY, same sign di-lepton search Same sign di-lepton search with Large jet multiplicity and missing transverse energy is a potential signature of SUSY events, This search confirms part of Jet- Met search excluded area. 24

25 arxiv: Search for SM Higgs, H WW Higgs boson search in WW final state: If WW comes from a spinless Higgs particle, they have to be both RH or LH, This constraint does not exist if WW is directly produced from proton proton collisions, Therefore leptons from W decays tend to fly collinearly with respect to pp->ww With 36pb -1 (2010 data) a Higgs boson in the four generation scenario, was excluded near the 2W mass region. 25

26 Search for SM Higgs, H WW Internal result on Higgs searches: This plot means that with 49pb -1 of data We are close to exclude m(h)=160 GeV Now we have 3 times larger data, The recently made available data is 150pb -1 As soon as this data is analyzed Tevatron Result on Higgs search is re-produced! 26

27 Exciting observations 27

28 Prospects for the Search for SM Higgs, H WW With 1fb -1 data (June? ) the Higgs boson mass between 130 GeV and 210 GeV can be excluded! 28

29 Two electrons with an invariant mass of more than 900 GeV! Could this be a hint for Z? 29

30 Two muons with invariant mass of 1 TeV! 30

31 The GeV bin shows little excess over SM expectation! A hint for H ϒϒ?! Questions is : Why up to the 3 rd neighboring bin, data and MS coincide but this single bin is higher than SM? 31

32 Conclusions: CMS has been verified and confirmed SM, No strong evidence of new models found yet, The next few months will be exciting, many results to be out! 32