The Cosmological Constant Puzzle Steven D Bass
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The Five Common Particles
The Five Common Particles The world around you consists of only three particles: protons, neutrons, and electrons. Protons and neutrons form the nuclei of atoms, and electrons glue everything together and create chemicals and materials. Along with the photon and the neutrino, these particles are essentially the only ones that exist in our solar system, because all the other subatomic particles have half-lives of typically 10-9 second or less, and vanish almost the instant they are created by nuclear reactions in the Sun, etc. Particles interact via the four fundamental forces of nature. Some basic properties of these forces are summarized below. (Other aspects of the fundamental forces are also discussed in the Summary of Particle Physics document on this web site.) Force Range Common Particles It Affects Conserved Quantity gravity infinite neutron, proton, electron, neutrino, photon mass-energy electromagnetic infinite proton, electron, photon charge -14 strong nuclear force ≈ 10 m neutron, proton baryon number -15 weak nuclear force ≈ 10 m neutron, proton, electron, neutrino lepton number Every particle in nature has specific values of all four of the conserved quantities associated with each force. The values for the five common particles are: Particle Rest Mass1 Charge2 Baryon # Lepton # proton 938.3 MeV/c2 +1 e +1 0 neutron 939.6 MeV/c2 0 +1 0 electron 0.511 MeV/c2 -1 e 0 +1 neutrino ≈ 1 eV/c2 0 0 +1 photon 0 eV/c2 0 0 0 1) MeV = mega-electron-volt = 106 eV. It is customary in particle physics to measure the mass of a particle in terms of how much energy it would represent if it were converted via E = mc2. -
Fundamentals of Particle Physics
Fundamentals of Par0cle Physics Particle Physics Masterclass Emmanuel Olaiya 1 The Universe u The universe is 15 billion years old u Around 150 billion galaxies (150,000,000,000) u Each galaxy has around 300 billion stars (300,000,000,000) u 150 billion x 300 billion stars (that is a lot of stars!) u That is a huge amount of material u That is an unimaginable amount of particles u How do we even begin to understand all of matter? 2 How many elementary particles does it take to describe the matter around us? 3 We can describe the material around us using just 3 particles . 3 Matter Particles +2/3 U Point like elementary particles that protons and neutrons are made from. Quarks Hence we can construct all nuclei using these two particles -1/3 d -1 Electrons orbit the nuclei and are help to e form molecules. These are also point like elementary particles Leptons We can build the world around us with these 3 particles. But how do they interact. To understand their interactions we have to introduce forces! Force carriers g1 g2 g3 g4 g5 g6 g7 g8 The gluon, of which there are 8 is the force carrier for nuclear forces Consider 2 forces: nuclear forces, and electromagnetism The photon, ie light is the force carrier when experiencing forces such and electricity and magnetism γ SOME FAMILAR THE ATOM PARTICLES ≈10-10m electron (-) 0.511 MeV A Fundamental (“pointlike”) Particle THE NUCLEUS proton (+) 938.3 MeV neutron (0) 939.6 MeV E=mc2. Einstein’s equation tells us mass and energy are equivalent Wave/Particle Duality (Quantum Mechanics) Einstein E -
Introduction to Particle Physics
SFB 676 – Projekt B2 Introduction to Particle Physics Christian Sander (Universität Hamburg) DESY Summer Student Lectures – Hamburg – 20th July '11 Outline ● Introduction ● History: From Democrit to Thomson ● The Standard Model ● Gauge Invariance ● The Higgs Mechanism ● Symmetries … Break ● Shortcomings of the Standard Model ● Physics Beyond the Standard Model ● Recent Results from the LHC ● Outlook Disclaimer: Very personal selection of topics and for sure many important things are left out! 20th July '11 Introduction to Particle Physics 2 20th July '11 Introduction to Particle PhysicsX Files: Season 2, Episode 233 … für Chester war das nur ein Weg das Geld für das eigentlich theoretische Zeugs aufzubringen, was ihn interessierte … die Erforschung Dunkler Materie, …ähm… Quantenpartikel, Neutrinos, Gluonen, Mesonen und Quarks. Subatomare Teilchen Die Geheimnisse des Universums! Theoretisch gesehen sind sie sogar die Bausteine der Wirklichkeit ! Aber niemand weiß, ob sie wirklich existieren !? 20th July '11 Introduction to Particle PhysicsX Files: Season 2, Episode 234 The First Particle Physicist? By convention ['nomos'] sweet is sweet, bitter is bitter, hot is hot, cold is cold, color is color; but in truth there are only atoms and the void. Democrit, * ~460 BC, †~360 BC in Abdera Hypothesis: ● Atoms have same constituents ● Atoms different in shape (assumption: geometrical shapes) ● Iron atoms are solid and strong with hooks that lock them into a solid ● Water atoms are smooth and slippery ● Salt atoms, because of their taste, are sharp and pointed ● Air atoms are light and whirling, pervading all other materials 20th July '11 Introduction to Particle Physics 5 Corpuscular Theory of Light Light consist out of particles (Newton et al.) ↕ Light is a wave (Huygens et al.) ● Mainly because of Newtons prestige, the corpuscle theory was widely accepted (more than 100 years) Sir Isaac Newton ● Failing to describe interference, diffraction, and *1643, †1727 polarization (e.g. -
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. -
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.. -
On Particle Physics
On Particle Physics Searching for the Fundamental US ATLAS The continuing search for the basic building blocks of matter is the US ATLAS subject of Particle Physics (also called High Energy Physics). The idea of fundamental building blocks has evolved from the concept of four elements (earth, air, fire and water) of the Ancient Greeks to the nineteenth century picture of atoms as tiny “billiard balls.” The key word here is FUNDAMENTAL — objects which are simple and have no structure — they are not made of anything smaller! Our current understanding of these fundamental constituents began to fall into place around 100 years ago, when experimenters first discovered that the atom was not fundamental at all, but was itself made of smaller building blocks. Using particle probes as “microscopes,” scientists deter- mined that an atom has a dense center, or NUCLEUS, of positive charge surrounded by a dilute “cloud” of light, negatively- charged electrons. In between the nucleus and electrons, most of the atom is empty space! As the particle “microscopes” became more and more powerful, scientists found that the nucleus was composed of two types of yet smaller constituents called protons and neutrons, and that even pro- tons and neutrons are made up of smaller particles called quarks. The quarks inside the nucleus come in two varieties, called “up” or u-quark and “down” or d-quark. As far as we know, quarks and electrons really are fundamental (although experimenters continue to look for evidence to the con- trary). We know that these fundamental building blocks are small, but just how small are they? Using probes that can “see” down to very small distances inside the atom, physicists know that quarks and electrons are smaller than 10-18 (that’s 0.000 000 000 000 000 001! ) meters across. -
The Fifth Force [Franklin 1993], Which Gives a Detailed Annotated History of the fifth Force Effort Along with Extensive References
Eur. Phys. J. H DOI: 10.1140/epjh/e2015-60044-5 THE EUROPEAN PHYSICAL JOURNAL H Personal recollection The fifth force: A personal history Ephraim Fischbacha Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA Received 12 September 2015 / Received in final form 14 September 2015 Published online 22 October 2015 c EDP Sciences, Springer-Verlag 2015 Abstract. On January 6, 1986, a paper written by our group appeared in Physical Review Letters entitled “Reanalysis of the E¨otv¨os Exper- iment”. In that Letter we reanalyzed a well-known 1922 paper by E¨otv¨os, Pek´ar, and Fekete (EPF) which compared the accelerations of samples of different composition to the Earth. Our surprising con- clusion was that “Although the E¨otv¨os experiment has been universally interpreted as having given null results, we find in fact that this is not the case”. Two days later a front page story appeared in the New York Times under the headline “Hints of 5th Force in Universe Challenge Galileo’s Findings”, and so was born the concept of a “fifth force”. In this personal history I review the pre-history which motivated our pa- per, and discuss details of our reanalysis of the EPF paper that have not been presented previously. Our work led to illuminating correspondence with Robert Dicke and Richard Feynman which are presented here for the first time. I also discuss an interesting meeting with T.D. Lee, one of whose papers with C.N. Yang provided part of the theoretical mo- tivation for our work. -
Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 11: Mesons and Baryons
Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 11: Mesons and Baryons !Measuring Jets !Fragmentation !Mesons and Baryons !Isospin and hypercharge !SU(3) flavour symmetry !Heavy Quark states 1 From Tuesday: Summary • In QCD, the coupling strength "S decreases at high momentum transfer (q2) increases at low momentum transfer. • Perturbation theory is only useful at high momentum transfer. • Non-perturbative techniques required at low momentum transfer. • At colliders, hard scatter produces quark, anti-quarks and gluons. • Fragmentation (hadronisation) describes how partons produced in hard scatter become final state hadrons. Need non-perturbative techniques. • Final state hadrons observed in experiments as jets. Measure jet pT, !, ! • Key measurement at lepton collider, evidence for NC=3 colours of quarks. + 2 σ(e e− hadrons) e R = → = N q σ(e+e µ+µ ) c e2 − → − • Next lecture: mesons and baryons! Griffiths chapter 5. 2 6 41. Plots of cross sections and related quantities + σ and R in e e− Collisions -2 10 ω φ J/ψ -3 10 ψ(2S) ρ Υ -4 ρ ! 10 Z -5 10 [mb] σ -6 R 10 -7 10 -8 10 2 1 10 10 Υ 3 10 J/ψ ψ(2S) Z 10 2 φ ω to theR Fermilab accelerator complex. In addition, both the CDF [11] and DØ detectors [12] 10 were upgraded. The resultsρ reported! here utilize an order of magnitude higher integrated luminosity1 than reported previously [5]. ρ -1 10 2 II. PERTURBATIVE1 QCD 10 10 √s [GeV] + + + + Figure 41.6: World data on the total cross section of e e− hadrons and the ratio R(s)=σ(e e− hadrons, s)/σ(e e− µ µ−,s). -
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. -
Vacuum Energy
Vacuum Energy Mark D. Roberts, 117 Queen’s Road, Wimbledon, London SW19 8NS, Email:[email protected] http://cosmology.mth.uct.ac.za/ roberts ∼ February 1, 2008 Eprint: hep-th/0012062 Comments: A comprehensive review of Vacuum Energy, which is an extended version of a poster presented at L¨uderitz (2000). This is not a review of the cosmolog- ical constant per se, but rather vacuum energy in general, my approach to the cosmological constant is not standard. Lots of very small changes and several additions for the second and third versions: constructive feedback still welcome, but the next version will be sometime in coming due to my sporadiac internet access. First Version 153 pages, 368 references. Second Version 161 pages, 399 references. arXiv:hep-th/0012062v3 22 Jul 2001 Third Version 167 pages, 412 references. The 1999 PACS Physics and Astronomy Classification Scheme: http://publish.aps.org/eprint/gateway/pacslist 11.10.+x, 04.62.+v, 98.80.-k, 03.70.+k; The 2000 Mathematical Classification Scheme: http://www.ams.org/msc 81T20, 83E99, 81Q99, 83F05. 3 KEYPHRASES: Vacuum Energy, Inertial Mass, Principle of Equivalence. 1 Abstract There appears to be three, perhaps related, ways of approaching the nature of vacuum energy. The first is to say that it is just the lowest energy state of a given, usually quantum, system. The second is to equate vacuum energy with the Casimir energy. The third is to note that an energy difference from a complete vacuum might have some long range effect, typically this energy difference is interpreted as the cosmological constant. -
Fifth Forces
FIFTH FORCES Symmetry Tests in Nuclei and Atoms KITP, Santa Barbara Jonathan Feng, UC Irvine 19 September 2016 19 Sep 2016 Feng 1 FUNDAMENTAL FORCES • We know of four fundamental forces Gravity Electromagnetism Strong Weak • A fifth one would be a big deal • Forces can be mediated by a host of particles: pions, Higgs boson, dilaton, towers of KK gravitons,... • In this talk, “5th force” refers to a force mediated by a new spin-1 gauge boson 19 Sep 2016 Feng 2 5TH FORCE MOTIVATION: UNIFICATION • Quantum numbers: e.g., SU(3) x SU(2) x U(1) à SO(10) • Unification of couplings: at a perturbative value and at a scale below Mplanck but high enough to satisfy proton decay • Any GUT group SO(10) or bigger has rank > 4, implies 5th force: U(1)B-L , Z’ gauge bosons, etc. 19 Sep 2016 Feng 3 5TH FORCE MOTIVATION: DARK MATTER • All evidence for dark matter is gravitational. Perhaps its in a hidden sector, composed of particles with no SM gauge interactions (electromagnetic, weak, strong) Hidden SM X • This hidden sector may have a rich structure with matter and forces of its own Lee, Yang (1956); Kobsarev, Okun, Pomeranchuk (1966); Blinnikov, Khlopov (1982); Foot, Lew, Volkas (1991); Hodges (1993); Berezhiani, Dolgov, Mohapatra (1995); … 19 Sep 2016 Feng 4 DM PORTALS • Astrophysics is sensitive to DM-DM interactions, but particle and nuclear physics are determined by DM-SM interactions • There are many ways the hidden particles could couple to us. Use effective operators as an organizing principle: where the operators are grouped by their mass dimension, with [scalar] = 1, [fermion] = 3/2, [Fµν] = 2 • M is a (presumably) large “mediator mass,” so start with dimension 4 operators. -
Effects of the Gravivector and Graviscalar Fields in N = 2,8
TTWOOlfiS LABORATORI NAZIONALI Dl FRASCATI SIS - Pubblicazioni LNF-96/026 (P) 30 Maggio 1996 la //" f"" ^ \p” o^Xp Effects of the Gravi vector and Graviscalar Fields in N = 2,8 Supergravity Stefano Bellucci INFN-Laboratori Nazionali di Frascati, P.O. Box 13, 1-00044 Frascati, Roma (Italy) and Valerio Faraoni Department of Physics and Astronomy, University of Victoria P.O. Box 3055, Victoria, B.C. V8W 3P6 (Canada) Abstract The available tests of the equivalence principle constrain the mass of the Higgs- like boson appearing in extended supergravity theories. We determine the con straints imposed by high precision experiments on the antigravity fields (gravivec- tor and graviscalar) arising from N = 2,8 supergravity. iimoN OF THIS DOCUMENT IS UNLIMITED PACS: 04.65+e, 04.80.Cc FOREIGN SALE! PROHIBITED Accepted for publication in Physics Letters B DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document — 2 — The discovery that N > 1 supergravity theories lead to antigravity is due to the work of the late J. Scherk [1, 2]. In a recent paper we have revived the interest for the implications of extended supergravity theories for antigravity [3]. This interest is connected to the high precision experiment at LEAR (CERN) measuring the difference in the gravitational acceleration of the proton and the antiproton [4]. For a review of earlier ideas about antigravity the reader is referred to the extensive article by Nieto and Goldman (5] and the references therein. The supergravity multiplet in the N = 2,8 cases contains, in addition to the graviton (J = 2), a vector field Aj, (J — 1).