DOCSLIB.ORG

Dark Matter and Collider Phenomenology of Non-Universal Gaugino Masses

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dark Matter and Collider Phenomenology of Non-Universal Gaugino Masses Dark Matter and Collider Phenomenology of Non-Universal Gaugino Masses A dissertation presented by Michael Holmes to The Department of Physics In partial fulfillment of the requirements for the degree of Doctor of Philosophy in the field of Physics Northeastern University Boston, Massachusetts April, 2010 1 c Michael Holmes, 2010 ALL RIGHTS RESERVED 2 Dark Matter and Collider Phenomenology of Non-Universal Gaugino Masses by Michael Holmes ABSTRACT OF DISSERTATION Submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy in Physics in the Graduate School of Arts and Sciences of Northeastern University, April, 2010 3 Abstract Signals of minimal supersymmetric models with non-universalities in the gaugino sector of the theory are analyzed at the CERN Large Hadron Collider (LHC) and in experiments searching for dark matter. Signals of dark matter including direct and indirect detection are investigated at depth in various supersymmetric frameworks. The parameter space of deflected mirage mediation, in which the soft terms receive contributions from the three main supersymmetry breaking mediation mechanisms, is investigated with emphasis on the neutralino sector and dark matter signals. The potential for non-universal gaugino masses to explain the recent CDMS II data is studied and possible implications for indirect dark matter detection experiments and LHC signatures are considered. Collider implications of non- universalities in the gaugino sector are examined with attention paid to specific signatures which are targeted to track the non-universalities. Further, the complementarity of dark matter and collider measurements is discussed with emphasis on breaking model degeneracies which may arise in LHC data. 4 Acknowledgements The work presented here was carried out with my Advisor, Professor Brent Nelson (North- eastern University), and with collaborators Dr. Ismet Altunkaynak (Northeastern Univer- sity), Professor Gordon Kane (University of Michigan) and Dr. Phillip Grajek (University of Michigan and currently at KEK). • I would like to thank my Thesis Committee: Professors Brent Nelson, Pran Nath and Emanuela Barberis for all the help and guidance over the years. • I would also like to thank the Northeastern University Physics department and its members for support and help during my graduate career and in particular Professors Haim Goldberg and George Alverson. • I offer many thanks to my colleague Dr. Ismet Altunkaynak for all the help and useful discussions over the years. • I offer the sincerest thanks and appreciation to Professor Brent Nelson. I have been privileged to have you as my Advisor over the years and I truly appreciate all your guidance and support during my time at Northeastern. • Finally, I would like to thank my family. 5 Contents Abstract 4 Acknowledgements 5 1 Introduction and Overview 9 2 The MSSM 13 2.1 The MSSM framework . 13 2.1.1 Particle content . 14 2.1.2 Review of global and local SUSY . 16 MSSM 2.1.3 WMSSM and Lsoft ............................ 19 2.2 High scale models . 22 2.3 Higgs potential and EWSB . 23 2.4 Superpartner masses . 25 2.5 Gaugino sector . 29 2.6 Signals of SUSY . 31 2.6.1 Dark matter . 31 2.6.2 Colliders . 32 3 Dark matter and the LSP 33 3.1 Relic density . 34 3.2 Direct detection . 36 3.3 Indirect detection . 40 4 Dark matter signals in deflected mirage mediation 45 4.1 DMM parameter space . 45 6 4.2 Survey of DM signatures . 55 4.2.1 Relic density . 55 4.2.2 Direct detection . 58 4.2.3 Gamma rays . 61 4.2.4 Muons . 65 4.2.5 Anti-Matter from cosmic rays . 66 4.2.6 Benchmarks . 68 4.3 Summary . 71 5 Dark matter signals of non-universal gaugino masses? 72 5.1 Benchmark models for CDMS II signal . 73 5.2 Other DM signals . 78 5.3 LHC signatures . 82 5.4 Summary . 84 6 LHC phenomenology of non-universal gaugino masses 86 6.1 Background . 87 6.2 Benchmarks . 89 6.3 Signature lists and distinguishing models . 90 6.4 Benchmark model LHC analysis . 93 6.5 Summary . 101 7 Lifting model degeneracies in LHC data using dark matter observations 102 7.1 LHC inverse problem . 102 7.2 Classifying degenerate pairs . 105 7.3 Direct detection . 108 7.4 Gamma rays . 117 7.5 Summary . 123 7 8 Conclusions 127 9 Appendix 130 Bibliography 133 8 Chapter 1 Introduction and Overview At the time of this writing the high energy community is entering a very exciting era. Up until now the Standard Model (SM) has been our best understanding of Nature which has been rigorously backed up by experimental observations. The SM is not complete however as it does not include neutrino masses (for example) and hence there must be some Beyond-the- Standard Model (BSM) physics. With data taking at the Large Hadron Collider (LHC) on the brink of occurring soon there may be new exciting evidence for BSM physics [1]. There are an array of possibilities for what the BSM physics may be and many are motivated from a high scale theory. Among the possible theories of BSM physics supersymmetry (SUSY) is highly-motivated for reasons such as gauge coupling unification and the existence of a solution to the hierarchy problem. Another intriguing property of SUSY is that the minimal extension of the SM includes a possible explanation for the dark matter (DM) problem, which was discovered after the model was proposed. The general SUSY framework is described in terms of the Minimal Supersymmetric Stan- dard Model (MSSM) and the parameter space is large, of dimension 124. Many possible experimental outcomes may result within the MSSM framework, and in particular the gau- gino sector of the theory is very compelling as it is relevant for the DM properties as well as signatures which may arise at the LHC. By signatures we refer to distinct final state topologies which arise from decays of supersymmetric particles such as trilepton final states, for example. The gaugino sector of SUSY also offers clues as to the nature of SUSY breaking which is very important to understand. It gives insight to the type of string-inspired model or Grand Unified Theory (GUT) which may govern the nature of the SUSY breaking. The 9 gaugino sector of the MSSM is intimately related to the dark matter particle within the MSSM, as well as to understanding the nature of SUSY breaking in general, it is therefore very interesting. In this thesis the work focuses on non-universal guagino masses (NUGM), which result in a rich low scale gaugino sector of the MSSM and therefore of possible dark matter observables along with corresponding LHC signatures which soon may be discovered. From a high scale perspective SUSY is the low scale effective theory of string theory. There are many possible string theories which currently exist and if SUSY is discovered it may offer support in the direction of string theory. String theories generally suffer from a stabilization problem associated with the scalar fields in the theory resulting in unstable vacua. Recent work suggests methods for stabilizing the vacuum in a string theory require the existence of multiple sources of SUSY breaking to contribute to the soft SUSY terms which results in non-universal gaugino masses. One such scenario has recently been introduced called deflected mirage mediation (DMM) in which gravity, anomaly and gauge mediated SUSY breaking mechanisms may be simultaneously present. An analysis is given here on the prospects of neutralino dark matter within the DMM model framework and what possible observations are possible. It is shown that there exist regions of the parameter space where all three mediation mechanisms are present and give a thermal relic abundance of neutralinos in line with the Wilkinson Microwave Anisotropy Probe (WMAP). Direct detection, and indirect detection including gamma ray, muon and anti-matter experiments are considered, and the investigated parameter space is shown to be in line with current experimental bounds. Discovery prospects are discussed for relevant upcoming experiments. Recently a possible signal of dark matter may have been observed by the CDMS II direct detection experimental group. An explanation for the observed dark matter scattering events can be explained quite readily within the context of Minimal Supergravity (mSUGRA) with non-universal gaugino masses. An analysis is given which can explain the possible dark matter signal using the mSURGA + NUGM. Furthermore various other dark matter signals are given along with a basic survey of LHC signatures expected for such models. 10 There exists a string motivated framework, called mirage mediation, in which the gaugino masses can be parametrized by a single non-universality parameter. This scenario is a simplified version of the DMM model in which no gauge mediation contributes. This offers a convenient way to study the effects of such non-universal gaugino masses, specifically the resulting LHC signatures. Two possible string scenarios are parametrized in such a way and the resulting LHC properties are given. The integrated luminosity necessary to differentiate the values of the non-universality parameter are given for the models along with further analysis of LHC signatures and model properties. An important issue is also the so-called LHC inverse problem. This arises when more than one set of model parameters can fit the LHC data, thus resulting in degenerate theory models which describe the data. A analysis is given by which degenerate SUSY models at the LHC are used to investigate the utility of dark matter observables to untangle the model degeneracies. The degenerate pairs can have gaugino sectors which involve non-universalities and hence interesting dark matter signals. Specifically direct detection and indirect gamma ray detection experiments are investigated and it is shown that they can be quite helpful at resolving the inverse problem.
Load more

Recommended publications
  • 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]
  • Supergravity and Its Legacy Prelude and the Play
    Supergravity and its Legacy Prelude and the Play Sergio FERRARA (CERN – LNF INFN) Celebrating Supegravity at 40 CERN, June 24 2016 S. Ferrara - CERN, 2016 1 Supergravity as carved on the Iconic Wall at the «Simons Center for Geometry and Physics», Stony Brook S. Ferrara - CERN, 2016 2 Prelude S. Ferrara - CERN, 2016 3 In the early 1970s I was a staff member at the Frascati National Laboratories of CNEN (then the National Nuclear Energy Agency), and with my colleagues Aurelio Grillo and Giorgio Parisi we were investigating, under the leadership of Raoul Gatto (later Professor at the University of Geneva) the consequences of the application of “Conformal Invariance” to Quantum Field Theory (QFT), stimulated by the ongoing Experiments at SLAC where an unexpected Bjorken Scaling was observed in inclusive electron- proton Cross sections, which was suggesting a larger space-time symmetry in processes dominated by short distance physics. In parallel with Alexander Polyakov, at the time in the Soviet Union, we formulated in those days Conformal invariant Operator Product Expansions (OPE) and proposed the “Conformal Bootstrap” as a non-perturbative approach to QFT. S. Ferrara - CERN, 2016 4 Conformal Invariance, OPEs and Conformal Bootstrap has become again a fashionable subject in recent times, because of the introduction of efficient new methods to solve the “Bootstrap Equations” (Riccardo Rattazzi, Slava Rychkov, Erik Tonni, Alessandro Vichi), and mostly because of their role in the AdS/CFT correspondence. The latter, pioneered by Juan Maldacena, Edward Witten, Steve Gubser, Igor Klebanov and Polyakov, can be regarded, to some extent, as one of the great legacies of higher dimensional Supergravity.
    [Show full text]
  • The Standard Model of Particle Physics and Beyond
    Clases de Master FisyMat, Desarrollos Actuales The Standard Model of particle physics and Beyond Date and time: 02/03 to 07/04/2021 15:30–17:00 Video/Sala CAJAL Organizer and Lecturer: Abdelhak Djouadi ([email protected]) You can find the pdfs of the lectures at: https://www.ugr.es/˜adjouadi/ 6. Supersymmetric theories 6.1 Basics of Supersymmetry 6.2 The minimal Supesymmetric Standard Model 6.3 The constrained MSSM’s 6.4 The superparticle spectrum 6.5 The Higgs sector of the MSSM 6.6 Beyond the MSSM 1 6.1 Basics of Supersymmetry Here, we give only basic facts needed later in the phenomenological discussion. For details on theoretical issues, see basic textbooks like Drees, Godbole, Roy. SUperSYmmetry: is a symmetry that relates scalars/vector bosons and fermions. The SUSY generators transform fermions into bosons and vice–versa, namely: FermionQ > Boson > , Boson > Fermion > Q| | Q| | must be an anti–commuting (and thus rather complicated) object. Q † is also a distinct symmetry generator: Q † Fermion > Boson > , † Boson > Fermion > Q | | Q | | Highly restricted [e.g., no go theorem] theories and in 4-dimension with chiral fermions: 1 , † carry spin– with left- and right- helicities and they should obey Q Q 2 .... The SUSY algebra: which schematically is given by µ , † = P , , =0 , †, † =0, {Qµ Q } µ {Q Q} a {Q Qa } [P , ]=0, [P , †]=0, [T , ]=0, [T , †]=0 Q Q Q Q P µ: is the generator of space–time transformations. T a are the generators of internal (gauge) symmetries. SUSY: unique extension of the Poincar´egroup of space–time symmetry to include ⇒ a four–dimensional Quantum Field Theory..
    [Show full text]
  • Gaugino-Induced Quark and Lepton Masses in a Truly Minimal Left-Right
    UCRHEP-T354 ULB-TH/03-16 NSF-KITP-03-32 May 2003 Gaugino-induced quark and lepton masses in a truly minimal left-right model J.-M. Fr`ere1,3 and Ernest Ma2,3 1 Service de Physique Th´eorique, Universit´eLibre de Bruxelles, B-1050 Brussels, Belgium 2 Physics Department, University of California, Riverside, California 92521, USA 3 Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA arXiv:hep-ph/0305155v2 20 Aug 2003 Abstract It has recently been proposed that all fundamental fermion masses (whether Dirac or Majorana) come from effective dimension-five operators in the context of a truly minimal left-right model. We show how a particularly economical scheme emerges in a supersymmetric framework, where chiral symmetry breaking originates in the gaugino sector. In the Standard Model of particle interactions, the spontaneous breaking of the SU(2)L × U(1)Y gauge symmetry to U(1)em is achieved through the vacuum expectation value of the scalar doublet Φ = (φ+,φ0). At the same time, since left-handed quarks and leptons are doublets under SU(2)L U(1)Y whereas right-handed quarks and leptons are singlets, chiral × symmetry is also broken by φ0 , thus allowing quarks and leptons to acquire the usual Dirac h i masses. The only exception is the neutrino which gets a small Majorana mass through the unique dimension-five operator [1, 2] fij 0 + 0 + Λ = (νiφ eiφ )(νjφ ejφ )+ H.c. (1) L 2Λ − − Suppose we now extend the standard-model gauge symmetry to SU(3)C SU(2)L × × SU(2)R U(1)B L [3], then the spontaneous breaking of SU(2)R U(1)B L to U(1)Y is × − × − simply achieved by the scalar doublet + 0 ΦR =(φ ,φ ) (1, 1, 2, 1), (2) R R ∼ where the notation refers to the dimension of the non-Abelian representation or the value of the Abelian charge B L or Y in the convention − 1 Y Q = I3L + I3R + (B L)= I3L + , (3) 2 − 2 while the corresponding field + 0 ΦL =(φ ,φ ) (1, 2, 1, 1), (4) L L ∼ becomes the same as the usual scalar doublet of the Standard Model, and breaks SU(2)L × U(1)Y in turn to U(1)em.
    [Show full text]
  • Table of Contents (Print)
    PERIODICALS PHYSICAL REVIEW Dä For editorial and subscription correspondence, Postmaster send address changes to: please see inside front cover (ISSN: 1550-7998) APS Subscription Services P.O. Box 41 Annapolis Junction, MD 20701 THIRD SERIES, VOLUME 90, NUMBER 5 CONTENTS D1 SEPTEMBER 2014 RAPID COMMUNICATIONS Measurement of the electric charge of the top quark in tt¯ events (8 pages) ........................................................ 051101(R) V. M. Abazov et al. (D0 Collaboration) BRST-symmetry breaking and Bose-ghost propagator in lattice minimal Landau gauge (5 pages) ............................. 051501(R) Attilio Cucchieri, David Dudal, Tereza Mendes, and Nele Vandersickel ARTICLES pffiffiffi Search for supersymmetry in events with four or more leptons in s ¼ 8 TeV pp collisions with the ATLAS detector (33 pages) ................................................................................................................................. 052001 G. Aad et al. (ATLAS Collaboration) pffiffiffi Low-mass vector-meson production at forward rapidity in p þ p collisions at s ¼ 200 GeV (12 pages) .................. 052002 A. Adare et al. (PHENIX Collaboration) Measurement of Collins asymmetries in inclusive production of charged pion pairs in eþe− annihilation at BABAR (26 pages) 052003 J. P. Lees et al. (BABAR Collaboration) Measurement of the Higgs boson mass from the H → γγ and H → ZZÃ → 4l channels in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector (35 pages) ................................................................... 052004 G. Aad et al. (ATLAS Collaboration) pffiffiffi Search for high-mass dilepton resonances in pp collisions at s ¼ 8 TeV with the ATLAS detector (30 pages) .......... 052005 G. Aad et al. (ATLAS Collaboration) Search for low-mass dark matter with CsI(Tl) crystal detectors (6 pages) .......................................................... 052006 H.
    [Show full text]
  • Hep-Ph/9811291
    CERN-TH/98-354 hep-ph/9811291 Quantum Gravity and Extra Dimensions at High-Energy Colliders Gian F. Giudice, Riccardo Rattazzi, and James D. Wells Theory Division, CERN CH-1211 Geneva 23, Switzerland Abstract Recently it has been pointed out that the characteristic quantum-gravity scale could be as low as the weak scale in theories with gravity propagating in higher dimensions. The observed smallness of Newton’s constant is a consequence of the large compactified volume of the extra dimensions. We investigate the consequences of this supposition for high-energy collider experiments. We do this by first compactifying the higher dimen- sional theory and constructing a 3 + 1-dimensional low-energy effective field theory of the graviton Kaluza-Klein excitations and their interactions with ordinary matter. We then consider graviton production processes, and select γ+ E and jet+ E signatures 6 6 for careful study. We find that both a 1 TeV e+e− collider and the CERN LHC will be able to reliably and perturbatively probe the fundamental gravity scale up to several arXiv:hep-ph/9811291v2 13 Mar 2000 TeV, with the precise value depending on the number of extra dimensions. Similarly, searches at LEP2 and the Tevatron are able to probe this scale up to approximately 1 TeV. We also discuss virtual graviton exchange, which induces local dimension-eight operators associated with the square of the energy-momentum tensor. We estimate the size of such operators and study their effects on ff¯ γγ observables. → CERN-TH/98-354 November 1998 Contents 1 Introduction 1 2 The Kaluza-Klein Excitations of the Graviton 7 3 Feynman Rules 14 4 Graviton Production Processes 18 5 Virtual Graviton Exchange 21 6 Graviton Production and Collider Experiments 24 6.1 e+e− andMuonColliders............................
    [Show full text]
  • Printed Here
    PHYSICAL REVIEW C VOLUME 55, NUMBER 2 FEBRUARY 1997 Selected Abstracts from Physical Review D Abstracts of papers published in Physical Review D which may be of interest to our readers are printed here. Superlight neutralino as a dark matter particle candidate. V. A. Constraints on big bang nucleosynthesis ~BBN! and on cosmo- Bednyakov, Max-Planck-Institut fu¨r Kernphysik, Postfach 103980, logical parameters from conflicting deuterium observations in dif- D-69029, Heidelberg, Germany and Laboratory of Nuclear Prob- ferent high redshift QSO systems are discussed. The high deuterium lems, Joint Institute for Nuclear Research, Moscow region, 141980 observations by Carswell et al., Songaila et al., and Rugers and Dubna, Russia; H. V. Klapdor-Kleingrothaus, Max-Planck-Institut Hogan are consistent with 4He and 7Li observations and standard fu¨r Kernphysik, Postfach 103980, D-69029, Heidelberg, Germany; BBN (Nn 53! and allows Nn<3.6 at 95% C.L., but are inconsistent S. G. Kovalenko, Max-Planck-Institut fu¨r Kernphysik, Postfach with local observations of D and 3He in the context of conventional 103980, D-69029, Heidelberg, Germany and Laboratory of Nuclear theories of stellar and galactic evolution. In contrast, the low deu- Problems, Joint Institute for Nuclear Research, Moscow region, terium observations by Tytler, Fan, and Burles and Burles and 141980 Dubna, Russia. ~Received 2 August 1996! Tytler are consistent with the constraints from local galactic obser- We address the question of how light the lightest supersymmetric vations, but require Nn51.960.3 at 68% C.L., excluding standard particle neutralino can be to be a reliable cold dark matter ~CDM! BBN at 99.9% C.L., unless the systematic uncertainties in the 4 particle candidate.
    [Show full text]
  • Jhep05(1999)013
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Received: March 30, 1999, Accepted: May 11, 1999 HYPER VERSION Sparticle masses from the superconformal anomaly Alex Pomarol∗ Theory Division, CERN CH-1211 Geneva 23, Switzerland JHEP05(1999)013 E-mail: [email protected] Riccardo Rattazzi INFN and Scuola Normale Superiore I-56100 Pisa, Italy E-mail: [email protected] Abstract: We discuss a recently proposed scenario where the sparticle masses are purely mediated by gravity through the superconformal anomaly. This scenario ele- gantly evades the supersymmetric flavor problem since soft masses, like the anomaly, are not directly sensitive to ultraviolet physics. However, its minimal incarnation fails by predicting tachyonic sleptons. We study the conditions for decoupling of heavy threshold effects and how these conditions are evaded. We use these results to build a realistic class of models where the non-decoupling effects of ultra-heavy vectorlike matter fields eliminate the tachyons. These models have a flavor invariant superspectrum similar to that of gauge mediated models. They, however, differ in several aspects: the gaugino masses are not unified, the colored sparticles are not much heavier than the others, the µ problem is less severe and the gravitino mass is well above the weak scale, m3=2 & 10 TeV. We also show that in models where an R-symmetry can be gauged, the associated D-term gives rise to soft terms that are similarly insensitive to the ultraviolet. Keywords: Supersymmetry Breaking, Supergravity Models, Supersymmetric Standard Model. ∗On leave of absence from IFAE, Universitat Aut`onoma de Barcelona, E-08193 Bellaterra, Barcelona.
    [Show full text]
  • Mass Degeneracy of the Higgsinos
    CERN–TH/95–337 Mass Degeneracy of the Higgsinos Gian F. Giudice1 and Alex Pomarol Theory Division, CERN CH-1211 Geneva 23, Switzerland Abstract The search for charginos and neutralinos at LEP2 can become problematic if these particles are almost mass degenerate with the lightest neutralino. Unfortunately this is the case in the region where these particles are higgsino-like. We show that, in this region, radiative corrections to the higgsino mass splittings can be as large as the tree-level values, if the mixing between the two stop states is large. We also show that the degree of degeneracy of the higgsinos substantially increases if a large phase is present in the higgsino mass term µ. CERN–TH/95–337 December 1995 1On leave of absence from INFN Sezione di Padova, Padua, Italy. The search for charginos (˜χ+) at LEP2 is one of the most promising ways of discovering low-energy supersymmetry. If theχ ˜+ decays into the lightest neutralino (˜χ0) and a virtual W +, it can be discovered at LEP2 (with a L = 500 pb−1) whenever its production cross R section is larger than about 0.1–0.3pbandmχ˜0 is within the range mχ˜0 ∼> 20 GeV and mχ˜+ − mχ˜0 ∼> 5–10 GeV [1]. Therefore, the chargino can be discovered almost up to the LEP2 kinematical limit, unless one of the following three conditions occurs: i) The sneutrino (˜ν) is light and the chargino is mainly gaugino-like. In this case theν ˜ t-channel exchange interferes destructively with the gauge-boson exchange and can reduce the chargino production cross section below the minimum values required for observability, 0.1–0.3 pb.
    [Show full text]
  • Arxiv: Instanton Operators and the Higgs Branch at Infinite Coupling
    Published for SISSA by Springer Received: October 26, 2016 Revised: March 14, 2017 Accepted: March 25, 2017 Published: April 10, 2017 Instanton operators and the Higgs branch at infinite JHEP04(2017)042 coupling Stefano Cremonesi,a Giulia Ferlito,b Amihay Hananyb and Noppadol Mekareeyac aDepartment of Mathematics, King's College London, The Strand, London WC2R 2LS, U.K. bTheoretical Physics Group, Imperial College London, Prince Consort Road, London, SW7 2AZ, U.K. cTheory Division, Physics Department, CERN, CH-1211, Geneva 23, Switzerland E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: The richness of 5d N = 1 theories with a UV fixed point at infinite coupling is due to the existence of local disorder operators known as instanton operators. By consid- ering the Higgs branch of SU(2) gauge theories with Nf ≤ 7 flavours at finite and infinite coupling, we write down the explicit chiral ring relations between instanton operators, the glueball superfield and mesons. Exciting phenomena appear at infinite coupling: the glue- ball superfield is no longer nilpotent and the classical chiral ring relations are quantum corrected by instanton operators bilinears. We also find expressions for the dressing of instanton operators of arbitrary charge. The same analysis is performed for USp(2k) with an antisymmetric hypermultiplet and pure SU(N) gauge theories. Keywords: Nonperturbative Effects, Solitons Monopoles and Instantons, Supersymmet- ric Gauge Theory ArXiv ePrint: 1505.06302
    [Show full text]
  • 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) × .
    [Show full text]
  • Loop-Induced CP Violation in the Gaugino and Higgsino Sectors of Supersymmetric Theories
    CERN-TH/99-379 THES-TP/99-xx hep-ph/9912253 December 1999 Loop-Induced CP Violation in the Gaugino and Higgsino Sectors of Supersymmetric Theories Apostolos Pilaftsis Theory Division, CERN, CH-1211 Geneva 23, Switzerland and Department of Theoretical Physics, University of Thessaloniki, GR 54006 Thessaloniki, Greece ABSTRACT We show that the gaugino and higgsino sectors of supersymmetric theories can nat- urally acquire observable CP violation through radiative effects which originate from large CP-violating trilinear couplings of the Higgs bosons to the third-generation scalar quarks. These CP-violating loop effects are not attainable by evolving the supersymmetric renormalization-group equations from a higher unification scale down to the electroweak one. We briefly discuss the phenomenological consequences of such a scenario, and as an example, calculate the two-loop contribution to the neutron electric dipole moment gener- ated by the one-loop chromo-electric dipole moment of the gluino. PACS numbers: 11.30.Er, 14.80.Er 1 Supersymmetric (SUSY) theories, including the minimal supersymmetric Standard Model (MSSM), predict several new unsuppressed CP-violating phases which generally lead to too large contributions to the electric dipole moments (EDM’s) of the neutron and electron [1, 2, 3, 4, 5, 6]. Several suggestions have been made in the literature to overcome such a CP crisis in SUSY theories. Apart from the cancellation mechanism proposed in [5], an interesting solution to the above CP-crisis problem is to assume that the first two generations are either very heavy above the TeV scale [4, 7] or they do not involve CP- violating phases in their trilinear couplings Af to the Higgs bosons [6].
    [Show full text]