Searches for Higgs Bosons Beyond the Standard Model with the CMS Experiment at the LHC Roger Wolf 18./19. November 2014 INSTITUTE OF EXPERIMENTAL PARTICLE PHYSICS (IEKP) – PHYSICS FACULTY KIT – University of the State of Baden-Wuerttemberg and www.kit.edu National Research Center of the Helmholtz Association
Road map... ● Short recap: ● Higgs bosons – what it is about? ● What do we know about the Higgs boson and how much space is still left for new physics in the Higgs sector? ● Higgs decays to invisible ( ) and related statement on DM interactions. ● Search for additional supersymmetric Higgs bosons: ● In the MSSM there are five Higgs bosons and we make strong statements on all of them! ● There is one detour in this, on an analysis of LFV in the Higgs sector. Disclaimer: This is a personal choice and by no means complete. Institute of Experimental Particle Physics (IEKP) 2
About Higgs: a short recap... ● Need Higgs mechanism to explain how particles can have mass and at the same time symmetry can be source of electroweak interactions. Institute of Experimental Particle Physics (IEKP) 3
About Higgs: a short recap... ● Need Higgs mechanism to explain how particles can have mass and at the same time symmetry can be source of electroweak interactions. ● Symmetry inherent to a system but not to its energy ground state ( → quantum vacuum ). ● In a quantum field theory ( QFT ) this can create new physical particles ( → Higgs boson(s) ). Non-zero vacuum expectation value Institute of Experimental Particle Physics (IEKP) 4
About Higgs: a short recap... ● Need Higgs mechanism to explain how particles can have mass and at the same time symmetry can be source of electroweak interactions. ● Symmetry inherent to a system but not to its energy ground state ( → quantum vacuum ). ● In a quantum field theory ( QFT ) this can create new physical particles ( → Higgs boson(s) ). Non-zero vacuum expectation value ● A Higgs boson has very a peculiar coupling structure, needed to fulfill the symmetry of the system ( example for fermions ): Institute of Experimental Particle Physics (IEKP) 5
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 Institute of Experimental Particle Physics (IEKP) 6
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. arXiv:1407.0558 arXiv:1312.5353 Institute of Experimental Particle Physics (IEKP) 7
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. ● We know its mass ( ): CMS-PAS-HIG-14-009 arXiv:1407.0558 arXiv:1407.3792 Overall fit of arXiv:1312.5353 electroweak precision observables Institute of Experimental Particle Physics (IEKP) 8
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. ● We know its mass ( ): CMS-PAS-HIG-14-009 arXiv:1401.6527 ● We have strong evidence that it couples to fermions ( ). arXiv:1401.6527 arXiv:1401.5041 Institute of Experimental Particle Physics (IEKP) 9
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. ● We know its mass ( ): CMS-PAS-HIG-14-009 ● We have strong evidence that it couples to fermions ( ). arXiv:1401.6527 ● We have reasons to believe that it is a spin 0 even object ( ). arXiv:1312.5353 arXiv:1312.5353 Institute of Experimental Particle Physics (IEKP) 10
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. ● We know its mass ( ): CMS-PAS-HIG-14-009 ● We have strong evidence that it couples to for fermions fermions ( ). arXiv:1401.6527 for vector bosons ● We have reasons to believe that it is a spin 0 even object ( ). arXiv:1312.5353 ● We know it's a Higgs boson! Institute of Experimental Particle Physics (IEKP) 11
Higgs: a known suspect ● We know it exists ( )! arXiv:1207.7235 4 th of July 2012 ● We know its a boson. ( of the ● We know its mass ( ): SM ) or is it just A Higgs boson? CMS-PAS-HIG-14-009 n o s o b s ● We have strong evidence that it couples to for fermions g g i fermions ( ). H arXiv:1401.6527 for vector bosons E H ● We have reasons to believe that it is a T s spin 0 even object ( ). i arXiv:1312.5353 h t s I ● We know it's a Higgs boson! Institute of Experimental Particle Physics (IEKP) 12
Why it is not THE Higgs boson ( of the SM ) (1) ● Gravity is not included in the SM. ● The SM suffers from the hierarchy problem. ● Dark matter is not included in the SM. ● Neutrino masses are not included in the SM. ● There are known deviations in from the SM expectation ( unresolved). (1) Arguments stolen from S. Heinemeyer (HH Higgs workshop 2014) Institute of Experimental Particle Physics (IEKP) 13
Why it is not THE Higgs boson ( of the SM ) (1) ● Gravity is not included in the SM. arXiv:hep-ph/0003170 ● The SM suffers from the hierarchy problem. ● Dark matter is not included in the SM. ● Neutrino masses are not included in the SM. ● There are known deviations in from the SM expectation ( unresolved). ● There must be physics beyond the SM! ● At what scale does it set in? ● (How) Does it influence the Higgs sector? (1) Arguments stolen from S. Heinemeyer (HH Higgs workshop 2014) Institute of Experimental Particle Physics (IEKP) 14
Space left for new physics in the Higgs sector ● Couplings are determined within to accuracy. CMS-PAS-HIG-14-009 Institute of Experimental Particle Physics (IEKP) 15
Space left for new physics in the Higgs sector ● Couplings are determined within to accuracy. ● Fixing all tree-level couplings to the SM ( ) & introducing effective couplings for loop induced processes ( ) leaves room for @ 95% CL. CMS-PAS-HIG-14-009 Institute of Experimental Particle Physics (IEKP) 16
Space left for new physics in the Higgs sector ● Couplings are determined within to accuracy. ● Fixing all tree-level couplings to the SM ( ) & introducing effective couplings for loop induced processes ( ) leaves room for @ 95% CL. ● Adding maximal freedom to the fit leaves room for @ 95% CL. CMS-PAS-HIG-14-009 Institute of Experimental Particle Physics (IEKP) 17
Direct searches for ( ) arXiv:1404.1344 Institute of Experimental Particle Physics (IEKP) 18
Direct searches for ( ) arXiv:1404.1344 s-channel 58% (obs) 44% (exp) Institute of Experimental Particle Physics (IEKP) 19
Direct searches for ( ) arXiv:1404.1344 s-channel t-channel 58% (obs) 44% (exp) q q Institute of Experimental Particle Physics (IEKP) 20
Direct searches for ( ) arXiv:1404.1344 s-channel t-channel q q Institute of Experimental Particle Physics (IEKP) 21
SUSY particles as DM candidates ● Extension of SM by a last remaining, non-trivial, symmetry operation (boson ↔ fermion), SUSY, can cure many shortcomings of SM: ● E.g. lightest SUSY particle (LSP) perfect candidate for . ● Problem: SUSY itself is broken! Institute of Experimental Particle Physics (IEKP) 22
Higgs sector in the MSSM ● Five neutral Higgs bosons predicted: ● MSSM mass requirements at tree level: two free parameters: , arXiv:hep-ph/0503173 Institute of Experimental Particle Physics (IEKP) 23
Enhancement of down-type couplings ● In MSSM coupling to down-type fermions enhanced for . ● Interesting decay channels: ● ( ) ( ) ● ● Interesting production modes: (“ ”) (“ ”) expect MSSM here! CMS-PAS-HIG-14-009 Institute of Experimental Particle Physics (IEKP) 24
Search for ( ) arXiv:1408.3316 of all decay modes. ● Search for 2 isolated high leptons ( , , ). ● Reduce obvious backgrounds (use on ) & reconstruct . ● Exploit characteristics of production Six decay modes: mode to increase sensitivity. Institute of Experimental Particle Physics (IEKP) 25
Reconstruction of hadronic ● Exploit particle flow algorithm: distinguish between , and . ● Isolation (based on energy deposits in vicinity of reconstructed candidate). ● Discrimination against electrons (based on shower shape & ). ● Discrimination against muons. ● Allows for independent cross check of energy calibration ( use 3% uncert. ). ● Efficiency ( fakerate), flat as function of and . Compatible w/ mass requirements Institute of Experimental Particle Physics (IEKP) 26
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