Isospin: an Approximate Symmetry on the Quark Level
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Spin and Parity of the Λ(1405) Baryon
Spin and Parity of the (1405) Baryon here [1], precisely because of the difficulty in producing it, and in particular because it must be produced spin polarized for a measurement to be made. We used photoproduction data from the CLAS detector at Jefferson Lab. The reaction + p K+ + (1405) was analyzed in the decay channel (1405) + + , where the decay distribution to + and the variation of the + polarization with respect to the (1405) polarization direction determined the spin and parity. The (1405) was produced in the c.m. energy range K 2.55 < W < 2.85 GeV and for 0.6 coscm.. 0.9 . The decay angular distribution of the (1405) in its rest Every subatomic particle has a set of properties that frame was found to be isotropic, which means the define its identity. Beyond mass, charge, and magnetic particle is consistent with spin J = ½. The first figure moment, each particle has discrete quantum numbers illustrates how the polarization P of a parent particle that include its spin angular momentum J and its with spin ½, in this case the (1405), transfers intrinsic parity P. The spin comes in integer steps of + starting from ½ for 3-quark objects (baryons). The polarization Q to the daughter baryon, in this case the , depending on whether the decay is in a spatial S wave parity is either positive (“+”) or negative (“”) (L=0) or P wave (L=1). This distinction is what depending on the inversion symmetry of its spatial wave determines the parity of the final state, and hence of the function. For example, the familiar proton and neutron parent. -
Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays
Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays !Resonances !Heavy Meson and Baryons !Decays and Quantum numbers !CKM matrix 1 Announcements •No lecture on Friday. •Remaining lectures: •Tuesday 13 March •Friday 16 March •Tuesday 20 March •Friday 23 March •Tuesday 27 March •Friday 30 March •Tuesday 3 April •Remaining Tutorials: •Monday 26 March •Monday 2 April 2 From Friday: Mesons and Baryons Summary • Quarks are confined to colourless bound states, collectively known as hadrons: " mesons: quark and anti-quark. Bosons (s=0, 1) with a symmetric colour wavefunction. " baryons: three quarks. Fermions (s=1/2, 3/2) with antisymmetric colour wavefunction. " anti-baryons: three anti-quarks. • Lightest mesons & baryons described by isospin (I, I3), strangeness (S) and hypercharge Y " isospin I=! for u and d quarks; (isospin combined as for spin) " I3=+! (isospin up) for up quarks; I3="! (isospin down) for down quarks " S=+1 for strange quarks (additive quantum number) " hypercharge Y = S + B • Hadrons display SU(3) flavour symmetry between u d and s quarks. Used to predict the allowed meson and baryon states. • As baryons are fermions, the overall wavefunction must be anti-symmetric. The wavefunction is product of colour, flavour, spin and spatial parts: ! = "c "f "S "L an odd number of these must be anti-symmetric. • consequences: no uuu, ddd or sss baryons with total spin J=# (S=#, L=0) • Residual strong force interactions between colourless hadrons propagated by mesons. 3 Resonances • Hadrons which decay due to the strong force have very short lifetime # ~ 10"24 s • Evidence for the existence of these states are resonances in the experimental data Γ2/4 σ = σ • Shape is Breit-Wigner distribution: max (E M)2 + Γ2/4 14 41. -
Arxiv:1502.07763V2 [Hep-Ph] 1 Apr 2015
Constraints on Dark Photon from Neutrino-Electron Scattering Experiments S. Bilmi¸s,1 I. Turan,1 T.M. Aliev,1 M. Deniz,2, 3 L. Singh,2, 4 and H.T. Wong2 1Department of Physics, Middle East Technical University, Ankara 06531, Turkey. 2Institute of Physics, Academia Sinica, Taipei 11529, Taiwan. 3Department of Physics, Dokuz Eyl¨ulUniversity, Izmir,_ Turkey. 4Department of Physics, Banaras Hindu University, Varanasi, 221005, India. (Dated: April 2, 2015) Abstract A possible manifestation of an additional light gauge boson A0, named as Dark Photon, associated with a group U(1)B−L is studied in neutrino electron scattering experiments. The exclusion plot on the coupling constant gB−L and the dark photon mass MA0 is obtained. It is shown that contributions of interference term between the dark photon and the Standard Model are important. The interference effects are studied and compared with for data sets from TEXONO, GEMMA, BOREXINO, LSND as well as CHARM II experiments. Our results provide more stringent bounds to some regions of parameter space. PACS numbers: 13.15.+g,12.60.+i,14.70.Pw arXiv:1502.07763v2 [hep-ph] 1 Apr 2015 1 CONTENTS I. Introduction 2 II. Hidden Sector as a beyond the Standard Model Scenario 3 III. Neutrino-Electron Scattering 6 A. Standard Model Expressions 6 B. Very Light Vector Boson Contributions 7 IV. Experimental Constraints 9 A. Neutrino-Electron Scattering Experiments 9 B. Roles of Interference 13 C. Results 14 V. Conclusions 17 Acknowledgments 19 References 20 I. INTRODUCTION The recent discovery of the Standard Model (SM) long-sought Higgs at the Large Hadron Collider is the last missing piece of the SM which is strengthened its success even further. -
The Subatomic Particle Mass Spectrum
The Subatomic Particle Mass Spectrum Robert L. Oldershaw 12 Emily Lane Amherst, MA 01002 USA [email protected] Key Words: Subatomic Particles; Particle Mass Spectrum; General Relativity; Kerr Metric; Discrete Self-Similarity; Discrete Scale Relativity 1 Abstract: Representative members of the subatomic particle mass spectrum in the 100 MeV to 7,000 MeV range are retrodicted to a first approximation using the Kerr solution of General Relativity. The particle masses appear to form a restricted set of quantized values of a Kerr- based angular momentum-mass relation: M = n1/2 M, where values of n are a set of discrete integers and M is a revised Planck mass. A fractal paradigm manifesting global discrete self- similarity is critical to a proper determination of M, which differs from the conventional Planck mass by a factor of roughly 1019. This exceedingly simple and generic mass equation retrodicts the masses of a representative set of 27 well-known particles with an average relative error of 1.6%. A more rigorous mass formula, which includes the total spin angular momentum rule of Quantum Mechanics, the canonical spin values of the particles, and the dimensionless rotational parameter of the Kerr angular momentum-mass relation, is able to retrodict the masses of the 8 dominant baryons in the 900 MeV to 1700 MeV range at the < 99.7% > level. 2 “There remains one especially unsatisfactory feature [of the Standard Model of particle physics]: the observed masses of the particles, m. There is no theory that adequately explains these numbers. We use the numbers in all our theories, but we do not understand them – what they are, or where they come from. -
FUNDAMENTAL PARTICLES Year 14 Physics Erin Hannigan
FUNDAMENTAL PARTICLES Year 14 Physics Erin Hannigan 1 Key Word List ■ Natural Philosophy – the science of matter and energy and their interactions. ■ Hadron – any elementary particle that interacts strongly with other particles. ■ Lepton – an elementary particle that participates in weak interactions. ■ Subatomic Particle – a body having finite mass and internal structure but negligible dimensions. ■ Quark – any of a number f subatomic particles carrying a fractional electric charge, postulated as building blocks of the hadrons. Quarks have not been directly observed but theoretical predictions based on their existence have been confirmed experimentally. ■ Atom – the smallest component of an element having the chemical properties of the element. 2 Fundamental Particles ■ Fundamental particles (also called elementary particles) are the smallest building blocks of the universe. The key characteristic of fundamental particles is that they have no internal structure. ■ There are two type of fundamental particles: – Particles that make up all matter, called fermions – Particles that carry force, called bosons ■ The four fundamental forces include: – Gravity – The weak force – Electromagnetism – The strong force 3 The Four Fundamental Forces ■ The four fundamental forces of nature govern everything that happens in the universe. ■ Gravity – The attraction between two objects that have mass or energy ■ The weak force – Responsible for particle decay – Physicists describe this interaction through the exchange of force-carrying particles called -
Introduction to Subatomic- Particle Spectrometers∗
IIT-CAPP-15/2 Introduction to Subatomic- Particle Spectrometers∗ Daniel M. Kaplan Illinois Institute of Technology Chicago, IL 60616 Charles E. Lane Drexel University Philadelphia, PA 19104 Kenneth S. Nelsony University of Virginia Charlottesville, VA 22901 Abstract An introductory review, suitable for the beginning student of high-energy physics or professionals from other fields who may desire familiarity with subatomic-particle detection techniques. Subatomic-particle fundamentals and the basics of particle in- teractions with matter are summarized, after which we review particle detectors. We conclude with three examples that illustrate the variety of subatomic-particle spectrom- eters and exemplify the combined use of several detection techniques to characterize interaction events more-or-less completely. arXiv:physics/9805026v3 [physics.ins-det] 17 Jul 2015 ∗To appear in the Wiley Encyclopedia of Electrical and Electronics Engineering. yNow at Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723. 1 Contents 1 Introduction 5 2 Overview of Subatomic Particles 5 2.1 Leptons, Hadrons, Gauge and Higgs Bosons . 5 2.2 Neutrinos . 6 2.3 Quarks . 8 3 Overview of Particle Detection 9 3.1 Position Measurement: Hodoscopes and Telescopes . 9 3.2 Momentum and Energy Measurement . 9 3.2.1 Magnetic Spectrometry . 9 3.2.2 Calorimeters . 10 3.3 Particle Identification . 10 3.3.1 Calorimetric Electron (and Photon) Identification . 10 3.3.2 Muon Identification . 11 3.3.3 Time of Flight and Ionization . 11 3.3.4 Cherenkov Detectors . 11 3.3.5 Transition-Radiation Detectors . 12 3.4 Neutrino Detection . 12 3.4.1 Reactor Neutrinos . 12 3.4.2 Detection of High Energy Neutrinos . -
The Ghost Particle 1 Ask Students If They Can Think of Some Things They Cannot Directly See but They Know Exist
Original broadcast: February 21, 2006 BEFORE WATCHING The Ghost Particle 1 Ask students if they can think of some things they cannot directly see but they know exist. Have them provide examples and reasoning for PROGRAM OVERVIEW how they know these things exist. NOVA explores the 70–year struggle so (Some examples and evidence of their existence include: [bacteria and virus- far to understand the most elusive of all es—illnesses], [energy—heat from the elementary particles, the neutrino. sun], [magnetism—effect on a com- pass], and [gravity—objects falling The program: towards Earth].) How do scientists • relates how the neutrino first came to be theorized by physicist observe and measure things that cannot be seen with the naked eye? Wolfgang Pauli in 1930. (They use instruments such as • notes the challenge of studying a particle with no electric charge. microscopes and telescopes, and • describes the first experiment that confirmed the existence of the they look at how unseen things neutrino in 1956. affect other objects.) • recounts how scientists came to believe that neutrinos—which are 2 Review the structure of an atom, produced during radioactive decay—would also be involved in including protons, neutrons, and nuclear fusion, a process suspected as the fuel source for the sun. electrons. Ask students what they know about subatomic particles, • tells how theoretician John Bahcall and chemist Ray Davis began i.e., any of the various units of mat- studying neutrinos to better understand how stars shine—Bahcall ter below the size of an atom. To created the first mathematical model predicting the sun’s solar help students better understand the neutrino production and Davis designed an experiment to measure size of some subatomic particles, solar neutrinos. -
Detection of a Hypercharge Axion in ATLAS
Detection of a Hypercharge Axion in ATLAS a Monte-Carlo Simulation of a Pseudo-Scalar Particle (Hypercharge Axion) with Electroweak Interactions for the ATLAS Detector in the Large Hadron Collider at CERN Erik Elfgren [email protected] December, 2000 Division of Physics Lule˚aUniversity of Technology Lule˚a, SE-971 87, Sweden http://www.luth.se/depts/mt/fy/ Abstract This Master of Science thesis treats the hypercharge axion, which is a hy- pothetical pseudo-scalar particle with electroweak interactions. First, the theoretical context and the motivations for this study are discussed. In short, the hypercharge axion is introduced to explain the dominance of matter over antimatter in the universe and the existence of large-scale magnetic fields. Second, the phenomenological properties are analyzed and the distin- guishing marks are underlined. These are basically the products of photons and Z0swithhightransversemomentaandinvariantmassequaltothatof the axion. Third, the simulation is carried out with two photons producing the axion which decays into Z0s and/or photons. The event simulation is run through the simulator ATLFAST of ATLAS (A Toroidal Large Hadron Col- lider ApparatuS) at CERN. Finally, the characteristics of the axion decay are analyzed and the crite- ria for detection are presented. A study of the background is also included. The result is that for certain values of the axion mass and the mass scale (both in the order of a TeV), the hypercharge axion could be detected in ATLAS. Preface This is a Master of Science thesis at the Lule˚a University of Technology, Sweden. The research has been done at Universit´edeMontr´eal, Canada, under the supervision of Professor Georges Azuelos. -
11. the Cabibbo-Kobayashi-Maskawa Mixing Matrix
11. CKM mixing matrix 103 11. THE CABIBBO-KOBAYASHI-MASKAWA MIXING MATRIX Revised 1997 by F.J. Gilman (Carnegie-Mellon University), where ci =cosθi and si =sinθi for i =1,2,3. In the limit K. Kleinknecht and B. Renk (Johannes-Gutenberg Universit¨at θ2 = θ3 = 0, this reduces to the usual Cabibbo mixing with θ1 Mainz). identified (up to a sign) with the Cabibbo angle [2]. Several different forms of the Kobayashi-Maskawa parametrization are found in the In the Standard Model with SU(2) × U(1) as the gauge group of literature. Since all these parametrizations are referred to as “the” electroweak interactions, both the quarks and leptons are assigned to Kobayashi-Maskawa form, some care about which one is being used is be left-handed doublets and right-handed singlets. The quark mass needed when the quadrant in which δ lies is under discussion. eigenstates are not the same as the weak eigenstates, and the matrix relating these bases was defined for six quarks and given an explicit A popular approximation that emphasizes the hierarchy in the size parametrization by Kobayashi and Maskawa [1] in 1973. It generalizes of the angles, s12 s23 s13 , is due to Wolfenstein [4], where one ≡ the four-quark case, where the matrix is parametrized by a single sets λ s12 , the sine of the Cabibbo angle, and then writes the other angle, the Cabibbo angle [2]. elements in terms of powers of λ: × By convention, the mixing is often expressed in terms of a 3 3 1 − λ2/2 λAλ3(ρ−iη) − unitary matrix V operating on the charge e/3 quarks (d, s,andb): V = −λ 1 − λ2/2 Aλ2 . -
Charm Meson Molecules and the X(3872)
Charm Meson Molecules and the X(3872) DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Masaoki Kusunoki, B.S. ***** The Ohio State University 2005 Dissertation Committee: Approved by Professor Eric Braaten, Adviser Professor Richard J. Furnstahl Adviser Professor Junko Shigemitsu Graduate Program in Professor Brian L. Winer Physics Abstract The recently discovered resonance X(3872) is interpreted as a loosely-bound S- wave charm meson molecule whose constituents are a superposition of the charm mesons D0D¯ ¤0 and D¤0D¯ 0. The unnaturally small binding energy of the molecule implies that it has some universal properties that depend only on its binding energy and its width. The existence of such a small energy scale motivates the separation of scales that leads to factorization formulas for production rates and decay rates of the X(3872). Factorization formulas are applied to predict that the line shape of the X(3872) differs significantly from that of a Breit-Wigner resonance and that there should be a peak in the invariant mass distribution for B ! D0D¯ ¤0K near the D0D¯ ¤0 threshold. An analysis of data by the Babar collaboration on B ! D(¤)D¯ (¤)K is used to predict that the decay B0 ! XK0 should be suppressed compared to B+ ! XK+. The differential decay rates of the X(3872) into J=Ã and light hadrons are also calculated up to multiplicative constants. If the X(3872) is indeed an S-wave charm meson molecule, it will provide a beautiful example of the predictive power of universality. -
06.08.2010 Yuming Wang the Charm-Loop Effect in B → K () L
The Charm-loop effect in B K( )`+` ! ∗ − Yu-Ming Wang Theoretische Physik I , Universitat¨ Siegen A. Khodjamirian, Th. Mannel,A. Pivovarov and Y.M.W. arXiv:1006.4945 Workshop on QCD and hadron physics, Weihai, August, 2010 1 0 2 4 6 8 10 12 14 16 18 20 0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 25 0 2 4 6 8 10 12 14 16 18 20 I. Motivation and introduction ( ) + B K ∗ ` `− induced by b s FCNC current: • prospectiv! e channels for the search! for new physics, a multitude of non-trival observables, Available measurements from BaBar, Belle, and CDF. Current averages (from HFAG, Sep., 2009): • BR(B Kl+l ) = (0:45 0:04) 10 6 ! − × − BR(B K l+l ) = (1:08+0:12) 10 6 : ! ∗ − 0:11 × − Invariant mass distribution and FBA (Belle,−2009): ) 2 1.2 /c 1 2 1 L / GeV 0.5 0.8 F -7 (10 0.6 2 0 0.4 1 0.2 dBF/dq 0.5 ) 0 FB 2 A /c 2 0.5 0 0.4 / GeV -7 0.3 (10 1 2 0.2 I A 0 0.1 dBF/dq 0 -1 0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 25 0 2 4 6 8 10 12 14 16 18 20 q2(GeV2/c2) q2(GeV2/c2) Yu-Ming Wang Workshop on QCD and hadron physics, Weihai, August, 2010 2 q2(GeV2/c2) q2(GeV2/c2) Decay amplitudes in SM: • A(B K( )`+` ) = K( )`+` H B ; ! ∗ − −h ∗ − j eff j i 4G 10 H = F V V C (µ)O (µ) ; eff p tb ts∗ i i − 2 iX=1 Leading contributions from O and O can be reduced to B K( ) 9;10 7γ ! ∗ form factors. -
Electro-Weak Interactions
Electro-weak interactions Marcello Fanti Physics Dept. | University of Milan M. Fanti (Physics Dep., UniMi) Fundamental Interactions 1 / 36 The ElectroWeak model M. Fanti (Physics Dep., UniMi) Fundamental Interactions 2 / 36 Electromagnetic vs weak interaction Electromagnetic interactions mediated by a photon, treat left/right fermions in the same way g M = [¯u (eγµ)u ] − µν [¯u (eγν)u ] 3 1 q2 4 2 1 − γ5 Weak charged interactions only apply to left-handed component: = L 2 Fermi theory (effective low-energy theory): GF µ 5 ν 5 M = p u¯3γ (1 − γ )u1 gµν u¯4γ (1 − γ )u2 2 Complete theory with a vector boson W mediator: g 1 − γ5 g g 1 − γ5 p µ µν p ν M = u¯3 γ u1 − 2 2 u¯4 γ u2 2 2 q − MW 2 2 2 g µ 5 ν 5 −−−! u¯3γ (1 − γ )u1 gµν u¯4γ (1 − γ )u2 2 2 low q 8 MW p 2 2 g −5 −2 ) GF = | and from weak decays GF = (1:1663787 ± 0:0000006) · 10 GeV 8 MW M. Fanti (Physics Dep., UniMi) Fundamental Interactions 3 / 36 Experimental facts e e Electromagnetic interactions γ Conserves charge along fermion lines ¡ Perfectly left/right symmetric e e Long-range interaction electromagnetic µ ) neutral mass-less mediator field A (the photon, γ) currents eL νL Weak charged current interactions Produces charge variation in the fermions, ∆Q = ±1 W ± Acts only on left-handed component, !! ¡ L u Short-range interaction L dL ) charged massive mediator field (W ±)µ weak charged − − − currents E.g.