1. Source: ref. [18]

2. The Standard Model Developed in the 1970’s Currently consists of 17 named particles and 3 of the 4 fundamental forces: strong nuclear force; weak nuclear force and electromagnetic force Combines elements of Albert Einstein’s theory of relativity and quantum theory Not complete!! Does not include force of gravity Latest addition = 2012, Higgs Boson Indicates that the fundamental forces behave similarly when in a high-energy environment, with the omission of gravity

3. Dark Matter

4. 1.Clockwise 2.Anticlockwise Proton is created Enters LINAC2 Beams created Fired into PS Booster Accelerated!!!Injected into Super Proton Synchrotron Gathers speed Divides into bunchesInjected into LHC Bunches divide Gather speed and collide At the LHC Source: http://imgur.com/gallery/5gxPH0d Important to note that we have used 8TeV instead of 7TeV

5. Proton-Proton Collisions Collision = new products formed The new products are the “debris” of the collision Study the debris to determine events Use of Feynman diagrams and reconstruction to determine if a dark matter candidate may have been found Higgs Boson = product of proton-proton collisions Recoil may imply dark matter present Source: Madgraph, Process generation, html page

6. Rapidity Incident velocities of particles taking part in the collision are along the beam axis (z-axis) Rapidity and angle ϕ are very closely related and expressed as ordered pair (γ; ϕ ) This represents the emission of a particle from an interaction point Rapidity: Alternative to the velocity – measure of the rate of motion y ------>

7. Transverse Momentum

8. Heavy Higgs Dark Matter (HHDM) Model Developed by the wits HEP team Proposes a dark matter candidate: 55-60GeV Proposes a heavy scalar Higgs Boson: 275-285GeV Aims to fit any excesses from LHC first run data Dark matter candidate – electrically neutral and non-interacting particle which may cause other particles to experience a recoil Dark matter candidate denoted χ (chi) Basis = Standard Model, HHDM Model proposes an extension of the Standard Model

9. [16] Measurements of the Total and Differential Higgs Boson Production Cross Sections Combining the H -> γγ and H -> ZZ* -> 4l Decay Channels at √s=8TeV with the ATLAS Detector, The ATLAS Collaboration, arXiv:1504.05833v1 [hep-ex] 21 Apr 2015 ATLAS Data – Comparison between run 1 data and SM prediction

10. Specifics MadGraph5 – simulations, 10000 events per parameter Pythia – decay particles Root – plot Rapidity

11. Higgs and Chi Production in HHDM Source: Madgraph, Process generation, html page

12. Parameters ( mass r, mass χ, branching ratio) Cross Section (pb – picobarn) mr275mχ55br50 mr275mχ55br60 mr275mχ55br70 mr275mχ60br50 mr275mχ60br60 mr275mχ60br70 mr285mχ55br50 mr285mχ55br60 mr285mχ55br70 mr285mχ60br50 mr285mχ60br60 mr285mχ60br70 Cross Sections per 10000 events HHDM Model Standard Model

13. Histogram showing the Higgs boson rapidity for 10000 events as per the Standard Model. Created on ROOT SM Higgs Rapidity Distribution Number of Events

14. Histograms comparing the Standard Model with the HHDM with parameters mr- 275GeV, mχ-55GeV and branching ratios of 50%, 60% and 70%. Histograms comparing the Standard Model with the HHDM with parameters mr- 275GeV, mχ-60GeV and branching ratios of 50%, 60% and 70%. Number of Events Comparison of the Higgs Rapidity Distribution between HHDM and SM HHDM Higgs Rapidity Distributions with branching ratios of 50; 60 and 70% SM Higgs Rapidity Distribution HHDM Higgs Rapidity Distributions with branching ratios of 50; 60 and 70% SM Higgs Rapidity Distribution

15. Histograms comparing the Standard Model with the HHDM with parameters mr- 285GeV, mχ-55GeV and branching ratios of 50%, 60% and 70%. Histograms comparing the Standard Model with the HHDM with parameters mr- 285GeV, mχ-60GeV and branching ratios of 50%, 60% and 70%. Number of Events Comparison of the Higgs Rapidity Distribution between HHDM and SM HHDM Higgs Rapidity Distributions with branching ratios of 50; 60 and 70% SM Higgs Rapidity Distribution HHDM Higgs Rapidity Distributions with branching ratios of 50; 60 and 70% SM Higgs Rapidity Distribution

16. Conclusions Similar results for each of the 12 parameters run Therefore a similar trend in comparison to the Standard Model Between the rapidity of -2 and +2 we see a drop in the Standard Model and an increase in the HHDM model – Higgs production is more central Fluctuations are very small when compared to the Standard Model The excess in cross sections seen in the ATLAS data can be accounted for by the HHDM model LHC run 2 may present more accurate data to test against

17. References [1] CERN, Dark Matter, http://home.web.cern.ch/about/physics/dark-matter, 2015 [2] Investigating Dark Matter Production in the LHC using the ATLAS Detector, MSc Research Proposal, Stefan von Buddenbrock, University of the Witwatersrand, 2015 [3] The Physics Hypertextbook, The Standard Model, http://physics.info/standard/, 2015 [4] University of Oregon, Elementary Particles, http://abyss.uoregon.edu/js/ast123/lectures/lec07, 2015 [5]The Standard Model, Elementary Particles electron6.phys.utk.edu/phys250/modules/module%206 [6] How the Large Hadron Collider works, Jonathan Strickland, http://science.howstuffworks.com/science-vs-myth/everyday-myths/large-hadron-collider4.htm [7] IT Infrastructure: Higgs Boson, LHC and Other Wonders of CERN, Nathan Eddy, http://www.eweek.com/c/a/IT-Infrastructure/Higgs-Boson-LHC-and-Other- Wonders-of-CERN-539468, 06 July 2012 [8] Experiments, LHC experiments, CERN, http://home.web.cern.ch/about/experiments [9] Rapidity and Pseudo-rapidity, E. Daw, 23 March 2012, http://www.hep.shef.ac.uk/edaw/PHY206 [10] Cross Section, Fermilab Today, Jim Pivarski, 01 March 2013, http://www.fnal.gov/pub/today/archive/archive_2013/today13-03-01.html [11] Higgs, Electroweak Physics and QCD-1, Deepak Kar, University of Glasgow, 15 December 2014 [12] Monte Carlo method or Monte Carlo analysis, David Tobiano, March 2011, http://whatis.techtarget.com/definition/Monte-Carlo-method-or-Monte-Carlo- analysis [13] MadGraph5_aMC@NLO, CTEQ School, 14 July 2014 [14] The Fourth Level of Learning Paper #17: Leaving the Cosmic Battlefield, Wes Penre, Written on Saturday, December 28, 2013. Posted on Friday, January 10, 2014. Edited by Professor Bob Stannard, http://wespenre.com/4/paper17-leaving-the-cosmic-battlefield.htm [15] Cross Section and Branching Ratio calculations, Computing Methods in High-Energy Physics, S. Lehti and V. Karimaki, 2010 [16] Measurements of the Total and Differential Higgs Boson Production Cross Sections Combining the H -> γγ and H -> ZZ* -> 4l Decay Channels at √s=8TeV with the ATLAS Detector, The ATLAS Collaboration, arXiv:1504.05833v1 [hep-ex] 21 Apr 2015 [17] Explaining the Higgs boson pT distributions with a new heavy scalar boson and a dark matter candidate. Stefan von Buddenbrock, Nabarun Chakrabarty, Alan S. Cornell, Deepak Kar, Mukesh Kumar, Tanumoy Mandal, Bruce Mellado, Biswarup Mukhopadhyaya and Robert G. Reed, School of Physics, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa, Regional Centre for Accelerator-based Particle Physics, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad - 211 019, India. June 2, 2015) [18] Will the Large Hadron Collider find dark matter? Atom smasher could soon solve one the universe's greatest mysteries, claims scientist, http://www.dailymail.co.uk/sciencetech/article-2891468/Will-Large-Hadron-Collider-dark-matter-Atom-smasher-soon-solve-one-universe-s-greatest-mysteries- claims-scientist.html [19] Frank Jordans, The Associated Press, Meet the pentaquark, a new kind of subatomic particle detected for the first time by Large Hadron Collider, 14 July 2015

18. THANK YOU!!

19. Detection of missing Energy in a Detector with Proton-Proton Collisions SUSY Parton-Parton Interaction Parton Proton Proton Remnants Partons (quark and gluons) in protons collide at high energies and produce heavy particles E=mc 2

20. Jets Electrons Muons Low P T particles High P T Particle escaping detection We cannot detect how much energy is lost with the proton remnant. But because protons bring very little transverse momentum, weakly interacting particles balance in the transverse plane with other particles, which are seen in the detectors Detection of missing Energy in a Detector with Proton-Proton Collisions

21. Cross Section The probability of a particular collision occurring with specified resulting products. The cross section can characterize the probability of a particular reaction taking place and/or the statistical nature of any scattering events, the cross section is normally conveyed in units of area (usually in barn). For the purposes of this project the cross section is measured in picobarn (denoted pb). Branching Ratio The branching ratio is the fraction, or ratio of events that decay in a certain way and is particle specific. This means that for a chosen particle’s decay there will be a specified ratio. Particles will decay in order to reach the most stable state available and therefore some particles will decay very quickly due to their unstable energies and momenta.

22. Interaction Points of Feynman Diagrams Gluons and photons = massless Only particles with mass will couple to Higgs Bosons Therefore gluons and photons will only couple to the Higgs Boson through loops

23. Measurement of Matter in the Universe Fluctuations in the cosmic microwave temperature traces fluctuations in the density of matter Fluctuations were imprinted shortly after the Big Bang Reveals not only important information about matter but also large scale structure of universe WMAP (Wilkinson Microwave Anisotropy Probe) – NASA Explorer mission Fundamental measurements of cosmology