Beyond the Standard Model: Supersymmetry
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Higgs Bosons and Supersymmetry
Higgs bosons and Supersymmetry 1. The Higgs mechanism in the Standard Model | The story so far | The SM Higgs boson at the LHC | Problems with the SM Higgs boson 2. Supersymmetry | Surpassing Poincar´e | Supersymmetry motivations | The MSSM 3. Conclusions & Summary D.J. Miller, Edinburgh, July 2, 2004 page 1 of 25 1. Electroweak Symmetry Breaking in the Standard Model 1. Electroweak Symmetry Breaking in the Standard Model Observation: Weak nuclear force mediated by W and Z bosons • M = 80:423 0:039GeV M = 91:1876 0:0021GeV W Z W couples only to left{handed fermions • Fermions have non-zero masses • Theory: We would like to describe electroweak physics by an SU(2) U(1) gauge theory. L ⊗ Y Left{handed fermions are SU(2) doublets Chiral theory ) right{handed fermions are SU(2) singlets f There are two problems with this, both concerning mass: gauge symmetry massless gauge bosons • SU(2) forbids m)( ¯ + ¯ ) terms massless fermions • L L R R L ) D.J. Miller, Edinburgh, July 2, 2004 page 2 of 25 1. Electroweak Symmetry Breaking in the Standard Model Higgs Mechanism Introduce new SU(2) doublet scalar field (φ) with potential V (φ) = λ φ 4 µ2 φ 2 j j − j j Minimum of the potential is not at zero 1 0 µ2 φ = with v = h i p2 v r λ Electroweak symmetry is broken Interactions with scalar field provide: Gauge boson masses • 1 1 2 2 MW = gv MZ = g + g0 v 2 2q Fermion masses • Y ¯ φ m = Y v=p2 f R L −! f f 4 degrees of freedom., 3 become longitudinal components of W and Z, one left over the Higgs boson D.J. -
Quantum Field Theory*
Quantum Field Theory y Frank Wilczek Institute for Advanced Study, School of Natural Science, Olden Lane, Princeton, NJ 08540 I discuss the general principles underlying quantum eld theory, and attempt to identify its most profound consequences. The deep est of these consequences result from the in nite number of degrees of freedom invoked to implement lo cality.Imention a few of its most striking successes, b oth achieved and prosp ective. Possible limitation s of quantum eld theory are viewed in the light of its history. I. SURVEY Quantum eld theory is the framework in which the regnant theories of the electroweak and strong interactions, which together form the Standard Mo del, are formulated. Quantum electro dynamics (QED), b esides providing a com- plete foundation for atomic physics and chemistry, has supp orted calculations of physical quantities with unparalleled precision. The exp erimentally measured value of the magnetic dip ole moment of the muon, 11 (g 2) = 233 184 600 (1680) 10 ; (1) exp: for example, should b e compared with the theoretical prediction 11 (g 2) = 233 183 478 (308) 10 : (2) theor: In quantum chromo dynamics (QCD) we cannot, for the forseeable future, aspire to to comparable accuracy.Yet QCD provides di erent, and at least equally impressive, evidence for the validity of the basic principles of quantum eld theory. Indeed, b ecause in QCD the interactions are stronger, QCD manifests a wider variety of phenomena characteristic of quantum eld theory. These include esp ecially running of the e ective coupling with distance or energy scale and the phenomenon of con nement. -
1 Standard Model: Successes and Problems
Searching for new particles at the Large Hadron Collider James Hirschauer (Fermi National Accelerator Laboratory) Sambamurti Memorial Lecture : August 7, 2017 Our current theory of the most fundamental laws of physics, known as the standard model (SM), works very well to explain many aspects of nature. Most recently, the Higgs boson, predicted to exist in the late 1960s, was discovered by the CMS and ATLAS collaborations at the Large Hadron Collider at CERN in 2012 [1] marking the first observation of the full spectrum of predicted SM particles. Despite the great success of this theory, there are several aspects of nature for which the SM description is completely lacking or unsatisfactory, including the identity of the astronomically observed dark matter and the mass of newly discovered Higgs boson. These and other apparent limitations of the SM motivate the search for new phenomena beyond the SM either directly at the LHC or indirectly with lower energy, high precision experiments. In these proceedings, the successes and some of the shortcomings of the SM are described, followed by a description of the methods and status of the search for new phenomena at the LHC, with some focus on supersymmetry (SUSY) [2], a specific theory of physics beyond the standard model (BSM). 1 Standard model: successes and problems The standard model of particle physics describes the interactions of fundamental matter particles (quarks and leptons) via the fundamental forces (mediated by the force carrying particles: the photon, gluon, and weak bosons). The Higgs boson, also a fundamental SM particle, plays a central role in the mechanism that determines the masses of the photon and weak bosons, as well as the rest of the standard model particles. -
A Young Physicist's Guide to the Higgs Boson
A Young Physicist’s Guide to the Higgs Boson Tel Aviv University Future Scientists – CERN Tour Presented by Stephen Sekula Associate Professor of Experimental Particle Physics SMU, Dallas, TX Programme ● You have a problem in your theory: (why do you need the Higgs Particle?) ● How to Make a Higgs Particle (One-at-a-Time) ● How to See a Higgs Particle (Without fooling yourself too much) ● A View from the Shadows: What are the New Questions? (An Epilogue) Stephen J. Sekula - SMU 2/44 You Have a Problem in Your Theory Credit for the ideas/example in this section goes to Prof. Daniel Stolarski (Carleton University) The Usual Explanation Usual Statement: “You need the Higgs Particle to explain mass.” 2 F=ma F=G m1 m2 /r Most of the mass of matter lies in the nucleus of the atom, and most of the mass of the nucleus arises from “binding energy” - the strength of the force that holds particles together to form nuclei imparts mass-energy to the nucleus (ala E = mc2). Corrected Statement: “You need the Higgs Particle to explain fundamental mass.” (e.g. the electron’s mass) E2=m2 c4+ p2 c2→( p=0)→ E=mc2 Stephen J. Sekula - SMU 4/44 Yes, the Higgs is important for mass, but let’s try this... ● No doubt, the Higgs particle plays a role in fundamental mass (I will come back to this point) ● But, as students who’ve been exposed to introductory physics (mechanics, electricity and magnetism) and some modern physics topics (quantum mechanics and special relativity) you are more familiar with.. -
New Physics of Strong Interaction and Dark Universe
universe Review New Physics of Strong Interaction and Dark Universe Vitaly Beylin 1 , Maxim Khlopov 1,2,3,* , Vladimir Kuksa 1 and Nikolay Volchanskiy 1,4 1 Institute of Physics, Southern Federal University, Stachki 194, 344090 Rostov on Don, Russia; [email protected] (V.B.); [email protected] (V.K.); [email protected] (N.V.) 2 CNRS, Astroparticule et Cosmologie, Université de Paris, F-75013 Paris, France 3 National Research Nuclear University “MEPHI” (Moscow State Engineering Physics Institute), 31 Kashirskoe Chaussee, 115409 Moscow, Russia 4 Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia * Correspondence: [email protected]; Tel.:+33-676380567 Received: 18 September 2020; Accepted: 21 October 2020; Published: 26 October 2020 Abstract: The history of dark universe physics can be traced from processes in the very early universe to the modern dominance of dark matter and energy. Here, we review the possible nontrivial role of strong interactions in cosmological effects of new physics. In the case of ordinary QCD interaction, the existence of new stable colored particles such as new stable quarks leads to new exotic forms of matter, some of which can be candidates for dark matter. New QCD-like strong interactions lead to new stable composite candidates bound by QCD-like confinement. We put special emphasis on the effects of interaction between new stable hadrons and ordinary matter, formation of anomalous forms of cosmic rays and exotic forms of matter, like stable fractionally charged particles. The possible correlation of these effects with high energy neutrino and cosmic ray signatures opens the way to study new physics of strong interactions by its indirect multi-messenger astrophysical probes. -
Baryon and Lepton Number Anomalies in the Standard Model
Appendix A Baryon and Lepton Number Anomalies in the Standard Model A.1 Baryon Number Anomalies The introduction of a gauged baryon number leads to the inclusion of quantum anomalies in the theory, refer to Fig. 1.2. The anomalies, for the baryonic current, are given by the following, 2 For SU(3) U(1)B , ⎛ ⎞ 3 A (SU(3)2U(1) ) = Tr[λaλb B]=3 × ⎝ B − B ⎠ = 0. (A.1) 1 B 2 i i lef t right 2 For SU(2) U(1)B , 3 × 3 3 A (SU(2)2U(1) ) = Tr[τ aτ b B]= B = . (A.2) 2 B 2 Q 2 ( )2 ( ) For U 1 Y U 1 B , 3 A (U(1)2 U(1) ) = Tr[YYB]=3 × 3(2Y 2 B − Y 2 B − Y 2 B ) =− . (A.3) 3 Y B Q Q u u d d 2 ( )2 ( ) For U 1 BU 1 Y , A ( ( )2 ( ) ) = [ ]= × ( 2 − 2 − 2 ) = . 4 U 1 BU 1 Y Tr BBY 3 3 2BQYQ Bu Yu Bd Yd 0 (A.4) ( )3 For U 1 B , A ( ( )3 ) = [ ]= × ( 3 − 3 − 3) = . 5 U 1 B Tr BBB 3 3 2BQ Bu Bd 0 (A.5) © Springer International Publishing AG, part of Springer Nature 2018 133 N. D. Barrie, Cosmological Implications of Quantum Anomalies, Springer Theses, https://doi.org/10.1007/978-3-319-94715-0 134 Appendix A: Baryon and Lepton Number Anomalies in the Standard Model 2 Fig. A.1 1-Loop corrections to a SU(2) U(1)B , where the loop contains only left-handed quarks, ( )2 ( ) and b U 1 Y U 1 B where the loop contains only quarks For U(1)B , A6(U(1)B ) = Tr[B]=3 × 3(2BQ − Bu − Bd ) = 0, (A.6) where the factor of 3 × 3 is a result of there being three generations of quarks and three colours for each quark. -
Composite Higgs Sketch
Composite Higgs Sketch Brando Bellazzinia; b, Csaba Cs´akic, Jay Hubiszd, Javi Serrac, John Terninge a Dipartimento di Fisica, Universit`adi Padova and INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy b SISSA, Via Bonomea 265, I-34136 Trieste, Italy c Department of Physics, LEPP, Cornell University, Ithaca, NY 14853 d Department of Physics, Syracuse University, Syracuse, NY 13244 e Department of Physics, University of California, Davis, CA 95616 [email protected], [email protected], [email protected], [email protected], [email protected] Abstract The couplings of a composite Higgs to the standard model fields can deviate substantially from the standard model values. In this case perturbative unitarity might break down before the scale of compositeness, Λ, is reached, which would suggest that additional composites should lie well below Λ. In this paper we account for the presence of an additional spin 1 custodial triplet ρ±;0. We examine the implications of requiring perturbative unitarity up to the scale Λ and find that one has to be close to saturating certain unitarity sum rules involving the Higgs and ρ couplings. Given these restrictions on the parameter space we investigate the main phenomenological consequences of the ρ's. We find that they can substantially enhance the h ! γγ rate at the LHC even with a reduced Higgs coupling to gauge bosons. The main existing LHC bounds arise from di-boson searches, especially in the experimentally clean channel ρ± ! W ±Z ! 3l + ν. We find that a large range of interesting parameter arXiv:1205.4032v4 [hep-ph] 30 Aug 2013 space with 700 GeV . -
MIT at the Large Hadron Collider—Illuminating the High-Energy Frontier
Mit at the large hadron collider—Illuminating the high-energy frontier 40 ) roland | klute mit physics annual 2010 gunther roland and Markus Klute ver the last few decades, teams of physicists and engineers O all over the globe have worked on the components for one of the most complex machines ever built: the Large Hadron Collider (LHC) at the CERN laboratory in Geneva, Switzerland. Collaborations of thousands of scientists have assembled the giant particle detectors used to examine collisions of protons and nuclei at energies never before achieved in a labo- ratory. After initial tests proved successful in late 2009, the LHC physics program was launched in March 2010. Now the race is on to fulfill the LHC’s paradoxical mission: to complete the Stan- dard Model of particle physics by detecting its last missing piece, the Higgs boson, and to discover the building blocks of a more complete theory of nature to finally replace the Standard Model. The MIT team working on the Compact Muon Solenoid (CMS) experiment at the LHC stands at the forefront of this new era of particle and nuclear physics. The High Energy Frontier Our current understanding of the fundamental interactions of nature is encap- sulated in the Standard Model of particle physics. In this theory, the multitude of subatomic particles is explained in terms of just two kinds of basic building blocks: quarks, which form protons and neutrons, and leptons, including the electron and its heavier cousins. From the three basic interactions described by the Standard Model—the strong, electroweak and gravitational forces—arise much of our understanding of the world around us, from the formation of matter in the early universe, to the energy production in the Sun, and the stability of atoms and mit physics annual 2010 roland | klute ( 41 figure 1 A photograph of the interior, central molecules. -
Introduction to Supersymmetry
Introduction to Supersymmetry Pre-SUSY Summer School Corpus Christi, Texas May 15-18, 2019 Stephen P. Martin Northern Illinois University [email protected] 1 Topics: Why: Motivation for supersymmetry (SUSY) • What: SUSY Lagrangians, SUSY breaking and the Minimal • Supersymmetric Standard Model, superpartner decays Who: Sorry, not covered. • For some more details and a slightly better attempt at proper referencing: A supersymmetry primer, hep-ph/9709356, version 7, January 2016 • TASI 2011 lectures notes: two-component fermion notation and • supersymmetry, arXiv:1205.4076. If you find corrections, please do let me know! 2 Lecture 1: Motivation and Introduction to Supersymmetry Motivation: The Hierarchy Problem • Supermultiplets • Particle content of the Minimal Supersymmetric Standard Model • (MSSM) Need for “soft” breaking of supersymmetry • The Wess-Zumino Model • 3 People have cited many reasons why extensions of the Standard Model might involve supersymmetry (SUSY). Some of them are: A possible cold dark matter particle • A light Higgs boson, M = 125 GeV • h Unification of gauge couplings • Mathematical elegance, beauty • ⋆ “What does that even mean? No such thing!” – Some modern pundits ⋆ “We beg to differ.” – Einstein, Dirac, . However, for me, the single compelling reason is: The Hierarchy Problem • 4 An analogy: Coulomb self-energy correction to the electron’s mass A point-like electron would have an infinite classical electrostatic energy. Instead, suppose the electron is a solid sphere of uniform charge density and radius R. An undergraduate problem gives: 3e2 ∆ECoulomb = 20πǫ0R 2 Interpreting this as a correction ∆me = ∆ECoulomb/c to the electron mass: 15 0.86 10− meters m = m + (1 MeV/c2) × . -
The Standard Model and Beyond Maxim Perelstein, LEPP/Cornell U
The Standard Model and Beyond Maxim Perelstein, LEPP/Cornell U. NYSS APS/AAPT Conference, April 19, 2008 The basic question of particle physics: What is the world made of? What is the smallest indivisible building block of matter? Is there such a thing? In the 20th century, we made tremendous progress in observing smaller and smaller objects Today’s accelerators allow us to study matter on length scales as short as 10^(-18) m The world’s largest particle accelerator/collider: the Tevatron (located at Fermilab in suburban Chicago) 4 miles long, accelerates protons and antiprotons to 99.9999% of speed of light and collides them head-on, 2 The CDF million collisions/sec. detector The control room Particle Collider is a Giant Microscope! • Optics: diffraction limit, ∆min ≈ λ • Quantum mechanics: particles waves, λ ≈ h¯/p • Higher energies shorter distances: ∆ ∼ 10−13 cm M c2 ∼ 1 GeV • Nucleus: proton mass p • Colliders today: E ∼ 100 GeV ∆ ∼ 10−16 cm • Colliders in near future: E ∼ 1000 GeV ∼ 1 TeV ∆ ∼ 10−17 cm Particle Colliders Can Create New Particles! • All naturally occuring matter consists of particles of just a few types: protons, neutrons, electrons, photons, neutrinos • Most other known particles are highly unstable (lifetimes << 1 sec) do not occur naturally In Special Relativity, energy and momentum are conserved, • 2 but mass is not: energy-mass transfer is possible! E = mc • So, a collision of 2 protons moving relativistically can result in production of particles that are much heavier than the protons, “made out of” their kinetic -
6 STANDARD MODEL: One-Loop Structure
6 STANDARD MODEL: One-Loop Structure Although the fundamental laws of Nature obey quantum mechanics, mi- croscopically challenged physicists build and use quantum field theories by starting from a classical Lagrangian. The classical approximation, which de- scribes macroscopic objects from physics professors to dinosaurs, has in itself a physical reality, but since it emerges only at later times of cosmological evolution, it is not fundamental. We should therefore not be too surprised if unforeseen special problems and opportunities emerge in the analysis of quantum perturbations away from the classical Lagrangian. The classical Lagrangian is used as input to the path integral, whose eval- uation produces another Lagrangian, the effective Lagrangian, Leff , which encodes all the consequences of the quantum field theory. It contains an infinite series of polynomials in the fields associated with its degrees of free- dom, and their derivatives. The classical Lagrangian is reproduced by this expansion in the lowest power of ~ and of momentum. With the notable exceptions of scale invariance, and of some (anomalous) chiral symmetries, we think that the symmetries of the classical Lagrangian survive the quanti- zation process. Consequently, not all possible polynomials in the fields and their derivatives appear in Leff , only those which respect the symmetries. The terms which are of higher order in ~ yield the quantum corrections to the theory. They are calculated according to a specific, but perilous path, which uses the classical Lagrangian as input. This procedure gener- ates infinities, due to quantum effects at short distances. Fortunately, most fundamental interactions are described by theories where these infinities can be absorbed in a redefinition of the input parameters and fields, i.e. -
Little Higgs Model Limits from LHC Arxiv:1307.5010V2 [Hep-Ph] 5 Sep
DESY 13-114 Little Higgs Model Limits from LHC Input for Snowmass 2013 Jurgen¨ Reuter1a, Marco Tonini2a, Maikel de Vries3a aDESY Theory Group, D{22603 Hamburg, Germany ABSTRACT The status of several prominent model implementations of the Little Higgs paradigm, the Littlest Higgs with and without discrete T-parity as well as the Simplest Little Higgs are reviewed. For this, we are taking into account a fit of 21 electroweak precision observables from LEP, SLC, Tevatron together with the full 25 fb−1 of Higgs data reported by ATLAS and CMS. For the Littlest Higgs with T-parity an outlook on corresponding direct searches at the 8 TeV LHC is included. We compare their competitiveness with the EW and Higgs data in terms of their exclusion potential. This contribution to the Snowmass procedure contains preliminary results of [1] and serves as a guideline for which regions in parameter space of Little Higgs models are still compatible for the upcoming LHC runs and future experiments at arXiv:1307.5010v2 [hep-ph] 5 Sep 2013 the energy frontier. For this purpose we propose two different benchmark scenarios for the Littlest Higgs with T-parity, one with heavy mirror quarks, one with light ones. [email protected] [email protected] [email protected] 1 Introduction: the Little Higgs Paradigm The first run of LHC at 2 TeV, 7 TeV, and 8 TeV centre of mass energies has brought as main results the discovery of a particle compatible with the properties of the Standard Model (SM) Higgs boson as well as with electroweak precision tests (EWPT), and no significant excesses that could be traced to new particles or forces.