DOCSLIB.ORG

Atomic Electric Dipole Moments and Cp Violation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Atomic Electric Dipole Moments and Cp Violation 261 ATOMIC ELECTRIC DIPOLE MOMENTS AND CP VIOLATION S.M.Barr Bartol Research Institute University of Delaware Newark, DE 19716 USA Abstract The subject of atomic electric dipole moments, the rapid recent progress in searching for them, and their significance for fundamental issues in particle theory is surveyed. particular it is shown how the edms of different kinds of atoms and molecules, as well Inas of the neutron, give vital information on the nature and origin of CP violation. Special stress is laid on supersymmetric theories and their consequences. 262 I. INTRODUCTION In this talk I am going to discuss atomic and molecular electric dipole moments (edms) from a particle theorist's point of view. The first and fundamental point is that permanent electric dipole moments violate both P and T. If we assume, as we are entitled to do, that OPT is conserved then we may speak equivalently of T-violation and OP-violation. I will mostly use the latter designation. That a permanent edm violates T is easily shown. Consider a proton. It has a magnetic dipole moment oriented along its spin axis. Suppose it also has an electric edm oriented, say, parallel to the magnetic dipole. Under T the electric dipole is not changed, as the spatial charge distribution is unaffected. But the magnetic dipole changes sign because current flows are reversed by T. Thus T takes a proton with parallel electric and magnetic dipoles into one with antiparallel moments. Now, if T is assumed to be an exact symmetry these two experimentally distinguishable kinds of proton will have the same mass. But we know that there is only one type of proton in the world, as otherwise the chart of nuclides would look very different. Thus either the proton has no edm or T is not an exact symmetry. The same argument applies to any other elementary particle (that is not "CP doubled" , which includes all the known ones). The same kind of argument shows that edms violate P. Now, CP violation is not well understood. That it is violated has been known since the classic experiment of Christenson, Cronin, Fitch and Turlay in 19641) for which Cronin and Fitch received the Nobel Prize in 1980. What that experiment showed was that CP was violated in the neutral Kaan system; in particular that KL decayed about two times in a thousand into two pions rather than three. It is remarkable that from that time until now - thirty years - CP violation has been observed in the laboratory in no other system than the neutral Kaons. I put in the qualifier "in the laboratory" because according to the currently standard picture of cosmology the cosmological baryon asymmetry (OBA), which is the fancy name for the fact that the matter in the universe is almost entirely matter rather than antimatter, is due to CP­ violating processes in the early universe.2l However, this fact, while it almost certainly points to OP-violating physics beyond the standard mode!3l, is of little help in understanding CP violation because there are so many possible scenarios of cosmological baryon generation. From the neutral kaon system there are two OP-violating quantities which can be measured, and has been known for thirty years [= 2.3 x 10-3), while the situation with 1 ([ E remainsE • murky,E with one experiment showing aE definitely non-zero value4l and the other6l fl being consistent with zero. The Particle Data Book gives the average of the two as 1 / [ = [ E E 2.2 ± x io-3. Withu so little data to work with it is not surprising that CP violation is poorly understood. Our other information about CP violation is in the form of null results. The most important of these is the limit on the neutron edm,6) which is d,. � 1.2 x lQ-25 e-cm. As we shall see, this leads to a major puzzle for particle theory called the Strong CP Problem. As we shall also see, the limits on the edms of atoms and molecules are also theoretically very important and will become greatly more important as they are pushed further, unless, of course atomic or molecular edms are seen, which would be epoch-making. It should be emphasized that the subject of CP violation is not some obscure corner of particle physics. It is a central topic of inquiry. It touches on such diverse issues as the edms of elementary particles and the origin of matter in the universe (as already noted), as well as on the nature of dark matter ("axions" are a prime candidate), the origin of galaxies, and the structure of physics beyond the so-called Standard Model of particle physics, as we shall see. And, of course, it is a question of fundamental interest in itself whether the laws of physics are T invariant and if not why. Fortunately, there are good prospects of learning more about CP violation over the next ten years. The main hope lies in the direction of further progress 263 in atomic and molecular edm experiments and in the study of neutral B mesons (a heavier analogue of the neutral kaons) at either "B factories" or at the LHO. There is also a large and promising effort being made to detect dark-matter axions by a variety of techniques, as is being discussed in other talks at this conference. II. CP VIOLATING PHASES OP violation arises, essentially, because of the presence in the underlying particle theory of non-trivial, physical, complex phases. Not all phases are physical. Some can be "rotated away"; that is, they can be absorbed by field redefinitions. Take, for example, QED, the theory of photons and electrons. In that theory the electron mass parameter can be complex: m.e'8eLeR+ h.c .. The phase Bis not physical as it is possible to eliminate it by redefining the righthanded electron field: ek e'8eR m.eLek+ h.c .. In simple theories there are often few enough parameters that= all the =>phases can be rotated away, as in QED. Such theories automatically conserve OP. But as a theory becomes more complicated the number of OP-violating phases tends to proliferate rapidly. III. CP VIOLATION IN THE STANDARD MODEL The Standard Model of particle physics is so simple that there are only two possible OP­ violating phases in it. They are called ti (or {jKM) and 8. ti is the Kobayashi-Maskawa phase which appears in the charged weak interactions, while 8 is the QOD vacuum angle which appears in the theory of the strong interactions. Let us discuss the latter first. A. The Strong CP Problem The Strong OP Problem, or B Problem, arises due to the fact that the neutron edm gets a contribution of order (10-16 e-cm) x sin 8. The experimental limit, therefore, implies that 8 10-9. The problem is to explain why, given the presumed fact that the weak interactions badly� violate OP (suggested by the neutral Kaon system), the strong interactions conserve OP to at least a part in a billion. Any explanation of this requires going beyond the Standard Model. There are two main approaches to solving this problem, the Peccei- Quinn mechanism7l and models with spontaneous OP breaking8l. The Peccei-Quinn mechanism involves the existence of the particles called "axions" . (Al­ ternatively there could be massless quarks. For example, it is much discussed whether the up quark could in actuality be massless.) In the axion models Ii comes out to be of order 10-15, generally. (In exotic variants it could be different.) This would give a value of order 10-31 e-cm for the 8 contribution to d,., far too small to be interesting experimentally. Axion models are not without difficulties. They are highly constrained by laboratory searches, and astrophysical and cosmological limits. Moreover there are potential problems with cosmic domain walls and with possible quantum gravity effects that have to be faced in constructing such models. Nev­ ertheless, the axion idea still has to be considered the most attractive solution to the strong OP Problem. The alternative approach is based on the idea that 8 is small as the consequence of some symmetry. The most likely possibility is that this symmetry is OP invariance itself. The idea is that OP is a good symmetry of the Lagrangian which is "spontaneously broken" by a OP-non-invariant ground state. In this way some OP-violating parameters may be small as a consequence of the underlying symmetry of the theory, while others may feel the spontaneous 264 OP breaking more directly and have larger values. In many of these models there is some difficulty in making 1J come out as small as 10-9. This may be even more of a problem in the context of supersymmetry. However, this idea has attractive features and quite viable and relatively simple models exist. One would expect that if this solution of the Strong OP Problem is the correct one that would be not far below present limits. We see, therefore, 1Jthat edm experiments already have had a major impact on particle theory. And it should be emphasized that the limits on 1Jcoming from searches for the edms of diamagnetic atoms and molecules are competitive with that coming from the neutron, and it is quite likely that may eventually first be seen in atomic experiments. If an edm of the neutron1J or a diamagnetic atom or molecule is observed, how will we know that it is a consequence of IJ? With just this kind of experiment we will not. There are many kinds of new OP-violating physics that could give rise to these effects.
Load more

Recommended publications
  • Symmetry and Gravity
    universe Article Making a Quantum Universe: Symmetry and Gravity Houri Ziaeepour 1,2 1 Institut UTINAM, CNRS UMR 6213, Observatoire de Besançon, Université de Franche Compté, 41 bis ave. de l’Observatoire, BP 1615, 25010 Besançon, France; [email protected] or [email protected] 2 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking GU5 6NT, UK Received: 05 September 2020; Accepted: 17 October 2020; Published: 23 October 2020 Abstract: So far, none of attempts to quantize gravity has led to a satisfactory model that not only describe gravity in the realm of a quantum world, but also its relation to elementary particles and other fundamental forces. Here, we outline the preliminary results for a model of quantum universe, in which gravity is fundamentally and by construction quantic. The model is based on three well motivated assumptions with compelling observational and theoretical evidence: quantum mechanics is valid at all scales; quantum systems are described by their symmetries; universe has infinite independent degrees of freedom. The last assumption means that the Hilbert space of the Universe has SUpN Ñ 8q – area preserving Diff.pS2q symmetry, which is parameterized by two angular variables. We show that, in the absence of a background spacetime, this Universe is trivial and static. Nonetheless, quantum fluctuations break the symmetry and divide the Universe to subsystems. When a subsystem is singled out as reference—observer—and another as clock, two more continuous parameters arise, which can be interpreted as distance and time. We identify the classical spacetime with parameter space of the Hilbert space of the Universe.
    [Show full text]
  • Consequences of Kaluza-Klein Covariance
    CONSEQUENCES OF KALUZA-KLEIN COVARIANCE Paul S. Wesson Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada Space-Time-Matter Consortium, http://astro.uwaterloo.ca/~wesson PACs: 11.10Kk, 11.25Mj, 0.45-h, 04.20Cv, 98.80Es Key Words: Classical Mechanics, Quantum Mechanics, Gravity, Relativity, Higher Di- mensions Addresses: Mail to Waterloo above; email: [email protected] Abstract The group of coordinate transformations for 5D noncompact Kaluza-Klein theory is broader than the 4D group for Einstein’s general relativity. Therefore, a 4D quantity can take on different forms depending on the choice for the 5D coordinates. We illustrate this by deriving the physical consequences for several forms of the canonical metric, where the fifth coordinate is altered by a translation, an inversion and a change from spacelike to timelike. These cause, respectively, the 4D cosmological ‘constant’ to be- come dependent on the fifth coordinate, the rest mass of a test particle to become measured by its Compton wavelength, and the dynamics to become wave-mechanical with a small mass quantum. These consequences of 5D covariance – whether viewed as positive or negative – help to determine the viability of current attempts to unify gravity with the interactions of particles. 1. Introduction Covariance, or the ability to change coordinates while not affecting the validity of the equations, is an essential property of any modern field theory. It is one of the found- ing principles for Einstein’s theory of gravitation, general relativity. However, that theory is four-dimensional, whereas many theories which seek to unify gravitation with the interactions of particles use higher-dimensional spaces.
    [Show full text]
  • Report of the Supersymmetry Theory Subgroup
    Report of the Supersymmetry Theory Subgroup J. Amundson (Wisconsin), G. Anderson (FNAL), H. Baer (FSU), J. Bagger (Johns Hopkins), R.M. Barnett (LBNL), C.H. Chen (UC Davis), G. Cleaver (OSU), B. Dobrescu (BU), M. Drees (Wisconsin), J.F. Gunion (UC Davis), G.L. Kane (Michigan), B. Kayser (NSF), C. Kolda (IAS), J. Lykken (FNAL), S.P. Martin (Michigan), T. Moroi (LBNL), S. Mrenna (Argonne), M. Nojiri (KEK), D. Pierce (SLAC), X. Tata (Hawaii), S. Thomas (SLAC), J.D. Wells (SLAC), B. Wright (North Carolina), Y. Yamada (Wisconsin) ABSTRACT Spacetime supersymmetry appears to be a fundamental in- gredient of superstring theory. We provide a mini-guide to some of the possible manifesta- tions of weak-scale supersymmetry. For each of six scenarios These motivations say nothing about the scale at which nature we provide might be supersymmetric. Indeed, there are additional motiva- tions for weak-scale supersymmetry. a brief description of the theoretical underpinnings, Incorporation of supersymmetry into the SM leads to a so- the adjustable parameters, lution of the gauge hierarchy problem. Namely, quadratic divergences in loop corrections to the Higgs boson mass a qualitative description of the associated phenomenology at future colliders, will cancel between fermionic and bosonic loops. This mechanism works only if the superpartner particle masses comments on how to simulate each scenario with existing are roughly of order or less than the weak scale. event generators. There exists an experimental hint: the three gauge cou- plings can unify at the Grand Uni®cation scale if there ex- I. INTRODUCTION ist weak-scale supersymmetric particles, with a desert be- The Standard Model (SM) is a theory of spin- 1 matter tween the weak scale and the GUT scale.
    [Show full text]
  • Naturalness and New Approaches to the Hierarchy Problem
    Naturalness and New Approaches to the Hierarchy Problem PiTP 2017 Nathaniel Craig Department of Physics, University of California, Santa Barbara, CA 93106 No warranty expressed or implied. This will eventually grow into a more polished public document, so please don't disseminate beyond the PiTP community, but please do enjoy. Suggestions, clarifications, and comments are welcome. Contents 1 Introduction 2 1.0.1 The proton mass . .3 1.0.2 Flavor hierarchies . .4 2 The Electroweak Hierarchy Problem 5 2.1 A toy model . .8 2.2 The naturalness strategy . 13 3 Old Hierarchy Solutions 16 3.1 Lowered cutoff . 16 3.2 Symmetries . 17 3.2.1 Supersymmetry . 17 3.2.2 Global symmetry . 22 3.3 Vacuum selection . 26 4 New Hierarchy Solutions 28 4.1 Twin Higgs / Neutral naturalness . 28 4.2 Relaxion . 31 4.2.1 QCD/QCD0 Relaxion . 31 4.2.2 Interactive Relaxion . 37 4.3 NNaturalness . 39 5 Rampant Speculation 42 5.1 UV/IR mixing . 42 6 Conclusion 45 1 1 Introduction What are the natural sizes of parameters in a quantum field theory? The original notion is the result of an aggregation of different ideas, starting with Dirac's Large Numbers Hypothesis (\Any two of the very large dimensionless numbers occurring in Nature are connected by a simple mathematical relation, in which the coefficients are of the order of magnitude unity" [1]), which was not quantum in nature, to Gell- Mann's Totalitarian Principle (\Anything that is not compulsory is forbidden." [2]), to refinements by Wilson and 't Hooft in more modern language.
    [Show full text]
  • UC Berkeley UC Berkeley Electronic Theses and Dissertations
    UC Berkeley UC Berkeley Electronic Theses and Dissertations Title Discoverable Matter: an Optimist’s View of Dark Matter and How to Find It Permalink https://escholarship.org/uc/item/2sv8b4x5 Author Mcgehee Jr., Robert Stephen Publication Date 2020 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California Discoverable Matter: an Optimist’s View of Dark Matter and How to Find It by Robert Stephen Mcgehee Jr. A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Hitoshi Murayama, Chair Professor Alexander Givental Professor Yasunori Nomura Summer 2020 Discoverable Matter: an Optimist’s View of Dark Matter and How to Find It Copyright 2020 by Robert Stephen Mcgehee Jr. 1 Abstract Discoverable Matter: an Optimist’s View of Dark Matter and How to Find It by Robert Stephen Mcgehee Jr. Doctor of Philosophy in Physics University of California, Berkeley Professor Hitoshi Murayama, Chair An abundance of evidence from diverse cosmological times and scales demonstrates that 85% of the matter in the Universe is comprised of nonluminous, non-baryonic dark matter. Discovering its fundamental nature has become one of the greatest outstanding problems in modern science. Other persistent problems in physics have lingered for decades, among them the electroweak hierarchy and origin of the baryon asymmetry. Little is known about the solutions to these problems except that they must lie beyond the Standard Model. The first half of this dissertation explores dark matter models motivated by their solution to not only the dark matter conundrum but other issues such as electroweak naturalness and baryon asymmetry.
    [Show full text]
  • Solving the Hierarchy Problem
    solving the hierarchy problem Joseph Lykken Fermilab/U. Chicago puzzle of the day: why is gravity so weak? answer: because there are large or warped extra dimensions about to be discovered at colliders puzzle of the day: why is gravity so weak? real answer: don’t know many possibilities may not even be a well-posed question outline of this lecture • what is the hierarchy problem of the Standard Model • is it really a problem? • what are the ways to solve it? • how is this related to gravity? what is the hierarchy problem of the Standard Model? • discuss concepts of naturalness and UV sensitivity in field theory • discuss Higgs naturalness problem in SM • discuss extra assumptions that lead to the hierarchy problem of SM UV sensitivity • Ken Wilson taught us how to think about field theory: “UV completion” = high energy effective field theory matching scale, Λ low energy effective field theory, e.g. SM energy UV sensitivity • how much do physical parameters of the low energy theory depend on details of the UV matching (i.e. short distance physics)? • if you know both the low and high energy theories, can answer this question precisely • if you don’t know the high energy theory, use a crude estimate: how much do the low energy observables change if, e.g. you let Λ → 2 Λ ? degrees of UV sensitivity parameter UV sensitivity “finite” quantities none -- UV insensitive dimensionless couplings logarithmic -- UV insensitive e.g. gauge or Yukawa couplings dimension-full coefs of higher dimension inverse power of cutoff -- “irrelevant” operators e.g.
    [Show full text]
  • Supersymmetry Breaking and Inflation from Higher Curvature
    Prepared for submission to JHEP Supersymmetry Breaking and Inflation from Higher Curvature Supergravity I. Dalianisa, F. Farakosb, A. Kehagiasa;c, A. Riottoc and R. von Ungeb aPhysics Division, National Technical University of Athens, 15780 Zografou Campus, Athens, Greece bInstitute for Theoretical Physics, Masaryk University, 611 37 Brno, Czech Republic cDepartment of Theoretical Physics and Center for Astroparticle Physics (CAP) 24 quai E. Ansermet, CH-1211 Geneva 4, Switzerland E-mail: [email protected], [email protected], [email protected], [email protected], [email protected] Abstract: The generic embedding of the R + R2 higher curvature theory into old- minimal supergravity leads to models with rich vacuum structure in addition to its well-known inflationary properties. When the model enjoys an exact R-symmetry, there is an inflationary phase with a single supersymmetric Minkowski vacuum. This appears to be a special case of a more generic set-up, which in principle may include R- symmetry violating terms which are still of pure supergravity origin. By including the latter terms, we find new supersymmetry breaking vacua compatible with single-field inflationary trajectories. We discuss explicitly two such models and we illustrate how arXiv:1409.8299v2 [hep-th] 22 Jan 2015 the inflaton is driven towards the supersymmetry breaking vacuum after the inflationary phase. In these models the gravitino mass is of the same order as the inflaton mass. Therefore, pure higher curvature supergravity may not only accommodate the proper inflaton field, but it may also provide the appropriate hidden sector for supersymmetry breaking after inflation has ended.
    [Show full text]
  • TASI 2008 Lectures: Introduction to Supersymmetry And
    TASI 2008 Lectures: Introduction to Supersymmetry and Supersymmetry Breaking Yuri Shirman Department of Physics and Astronomy University of California, Irvine, CA 92697. [email protected] Abstract These lectures, presented at TASI 08 school, provide an introduction to supersymmetry and supersymmetry breaking. We present basic formalism of supersymmetry, super- symmetric non-renormalization theorems, and summarize non-perturbative dynamics of supersymmetric QCD. We then turn to discussion of tree level, non-perturbative, and metastable supersymmetry breaking. We introduce Minimal Supersymmetric Standard Model and discuss soft parameters in the Lagrangian. Finally we discuss several mech- anisms for communicating the supersymmetry breaking between the hidden and visible sectors. arXiv:0907.0039v1 [hep-ph] 1 Jul 2009 Contents 1 Introduction 2 1.1 Motivation..................................... 2 1.2 Weylfermions................................... 4 1.3 Afirstlookatsupersymmetry . .. 5 2 Constructing supersymmetric Lagrangians 6 2.1 Wess-ZuminoModel ............................... 6 2.2 Superfieldformalism .............................. 8 2.3 VectorSuperfield ................................. 12 2.4 Supersymmetric U(1)gaugetheory ....................... 13 2.5 Non-abeliangaugetheory . .. 15 3 Non-renormalization theorems 16 3.1 R-symmetry.................................... 17 3.2 Superpotentialterms . .. .. .. 17 3.3 Gaugecouplingrenormalization . ..... 19 3.4 D-termrenormalization. ... 20 4 Non-perturbative dynamics in SUSY QCD 20 4.1 Affleck-Dine-Seiberg
    [Show full text]
  • Baryogenesis and Dark Matter from B Mesons: B-Mesogenesis
    Baryogenesis and Dark Matter from B Mesons: B-Mesogenesis Miguel Escudero Abenza [email protected] arXiv:1810.00880, PRD 99, 035031 (2019) with: Gilly Elor & Ann Nelson Based on: arXiv:2101.XXXXX with: Gonzalo Alonso-Álvarez & Gilly Elor New Trends in Dark Matter 09-12-2020 The Universe Baryonic Matter 5% 26% Dark Matter 69% Dark Energy Planck 2018 1807.06209 Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !2 Theoretical Understanding? Motivating Question: What fraction of the Energy Density of the Universe comes from Physics Beyond the Standard Model? 99.85%! Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !3 SM Prediction: Neutrinos 40% 60% Photons Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !4 The Universe Baryonic Matter 5% 26% Dark Matter 69% Dark Energy Planck 2018 1807.06209 Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !5 Baryogenesis and Dark Matter from B Mesons: B-Mesogenesis arXiv:1810.00880 Elor, Escudero & Nelson 1) Baryogenesis and Dark Matter are linked 2) Baryon asymmetry directly related to B-Meson observables 3) Leads to unique collider signatures 4) Fully testable at current collider experiments Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !6 Outline 1) B-Mesogenesis 1) C/CP violation 2) Out of equilibrium 3) Baryon number violation? 2) A Minimal Model & Cosmology 3) Implications for Collider Experiments 4) Dark Matter Phenomenology 5) Summary and Outlook Miguel Escudero (TUM) B-Mesogenesis New Trends in DM 09-12-20 !7 Baryogenesis
    [Show full text]
  • What Is Not the Hierarchy Problem (Of the SM Higgs)
    What is not the hierarchy problem (of the SM Higgs) Matěj Hudec Výjezdní seminář ÚČJF Malá Skála, 12 Apr 2019, lunchtime Our ecological footprint he FuFnu wni twhit th the ggs AbAebliealina nH iHiggs mmodoedlel ký MM. M. Maalinlinsský 5 (2013) EEPPJJCC 7 733, ,2 244115 (2013) 660 aarrXXiivv::11221122..44660 12 pgs. 2 Our ecological footprint the Aspects of FuFnu wni twhith the Aspects of ggs renormalization AbAebliealina nH iHiggs renormalization of spontaneously mmodoedlel of spontaneously broken gauge broken gauge theories theories ký MM. M. Maalinlinsský MASTER THESIS MASTER THESIS M. H. M. H. 5 (2013) supervised by M.M. EEPPJJCC 7 733, ,2 244115 (2013) supervised by M.M. iv:1212.4660 2016 aarrXXiv:1212.4660 2016 12 pgs. 56 pgs. 3 Our ecological footprint Aspects of Fun with the H Fun with the Aspects of ierarchy and n Higgs renormalization AbAebliealian Higgs renormalization dHecoup of spontaneously ierarclhing mmodoedlel of spontaneously y and broken gauge decoup broken gauge ling theories theories M. Hudec, M. Malinský M M. Malinský MASTER THESIS .M M. alinský MASTER THESIS Hudec, M. M M. H. alinský M. H. (hopeful 5 (2013) supervised by M.M. ly EPJC) EEPPJJCC 7 733, ,2 244115 (2013) supervised by M.M. arX (hopef iv:190u2lly. 0EPJ 12.4660 2016 4C4) 70 aarrXXiivv::112212.4660 a 2016 rXiv:190 2.04470 12 pgs. 56 pgs. 17 pgs. 4 Hierarchy problem – first thoughts 5 Hierarchy problem – first thoughts In particle physics, the hierarchy problem is the large discrepancy between aspects of the weak force and gravity. 6 Hierarchy problem – first thoughts In particle physics, the hierarchy problem is the large discrepancy between aspects of the weak force and gravity.
    [Show full text]
  • Peering Into the Universe and Its Ele Mentary
    A gigantic detector to explore elementary particle unification theories and the mysteries of the Universe’s evolution Peering into the Universe and its ele mentary particles from underground Ultrasensitive Photodetectors The planned Hyper-Kamiokande detector will consist of an Unified Theory and explain the evolution of the Universe order of magnitude larger tank than the predecessor, Super- through the investigation of proton decay, CP violation (the We have been developing the world’s largest photosensors, which exhibit a photodetection Kamiokande, and will be equipped with ultra high sensitivity difference between neutrinos and antineutrinos), and the efficiency two times greater than that of the photosensors. The Hyper-Kamiokande detector is both a observation of neutrinos from supernova explosions. The Super-Kamiokande photosensors. These new “microscope,” used to observe elementary particles, and a Hyper-Kamiokande experiment is an international research photosensors are able to perform light intensity “telescope”, used to study the Sun and supernovas through project aiming to become operational in the second half of and timing measurements with a much higher neutrinos. Hyper-Kamiokande aims to elucidate the Grand the 2020s. precision. The new Large-Aperture High-Sensitivity Hybrid Photodetector (left), the new Large-Aperture High-Sensitivity Photomultiplier Tube (right). The bottom photographs show the electron multiplication component. A megaton water tank The huge Hyper-Kamiokande tank will be used in order to obtain in only 10 years an amount of data corresponding to 100 years of data collection time using Super-Kamiokande. This Experimental Technique allows the observation of previously unrevealed The photosensors on the tank wall detect the very weak Cherenkov rare phenomena and small values of CP light emitted along its direction of travel by a charged particle violation.
    [Show full text]
  • CP Violation Beyond the Standard Model*
    INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS G: NUCLEAR AND PARTICLE PHYSICS J. Phys. G: Nucl. Part. Phys. 28 (2002) 345–358 PII: S0954-3899(02)30104-X CP violation beyond the standard model* GLKane1 and D D Doyle2 1 Randall Physics Laboratory, University of Michigan, Ann Arbor, MI 48109, USA 2 CPES, University of Sussex, Falmer, Brighton BN1 9QJ, UK E-mail: [email protected] Received 25 October 2001 Published 21 January 2002 Online at stacks.iop.org/JPhysG/28/345 Abstract In this paper a number of broad issues are raised about the origins of CP violation and how to test the ideas. 1. Introduction The fundamental sources of CP violation in theories of physics beyond the standard model is an important issue which has not been sufficiently studied. In this paper, we begin by discussing the possible origins of CP violation in string theory and the potential influence of its phenomenology on string theory. This naturally develops into a consideration of supersymmetry breaking, specifically the soft-breaking supersymmetric Lagrangian, Lsoft. There exist two extreme scenarios which may realistically accommodate CP violation; the first involves small soft phases and a large CKM phase, δCKM, whereas the second contains large soft phases and small δCKM. We argue that there is reasonable motivation for δCKM to be almost zero and that the latter scenario should be taken seriously. Consequently, it is appropriate to consider what CP violating mechanisms could allow for large soft phases, and hence measurements of these soft phases (which can be deduced from collider results, mixings and decays, experiments exploring the Higgs sector or from electric dipole moment values) provide some interesting phenomenological implications for physics beyond the standard model.
    [Show full text]