DOCSLIB.ORG

A Study of Cascade and Strange Baryon Production in Sulphur-Sulphur Interactions at 200 Gev/C Per Nucleon S

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Fysisk institutt NO9800037 NEI-NO--895 Strange and non-strange baryon and antibaryon production in sulphur-tungsten and sulphur-sulphur interactions at 200 A GeV/c by Alv Kjetil Holme November 1995 Universitetet i Bergen Bergen, Norway Fysisk institutt Strange and non-strange baryon and antibaryon production in sulphur-tungsten and sulphur-sulphur interactions at 200 A GeV/c by Alv Kjetil Holme a thesis submitted to Fysisk institutt, Universitetet i Bergen, in partial fulfilment of the requirements for the degree of Doctor Scientiarum November 1995 Universitetet i Bergen Bergen, Norway And since these things are so, it is necessary to think that in all the objects that are compound there existed many things of all sorts, and germs of all objects, having all sorts of forms and colours and flavours. - Anaxagoras Abstract A new phase of strongly interacting matter, the quark-gluon plasma, is predicted to exist at extreme energy densities. In this plasma, quarks and gluons are no longer confined inside hadrons. A relativistic heavy-ion collision is one likely way to produce the required energy density in a sufficiently large volume. The production of strange baryons and antibaryons is considered to be an important diagnostic tool for understanding the dynamics of matter under these extreme conditions. The WA85 collaboration has measured the production of strange particles (A, E~, Q~, and kaons) and antiparticles at central rapidities and high transverse momentum in central sulphur-tungsten collisions at 200 AGeV/c. The main results are the high E+/A ratio and the first observation of the Q~ and the Q+ in heavy-ion collisions. The WA94 collaboration has extended the strange particle studies of WA85 to sulphur- sulphur collisions. In addition, a Ring Imaging Cerenkov detector has been used to identify charged particles in order to determine the production of protons and antiprotons, and charged kaons and pions. The results on As and Es are very similar to the WA85 results. In particular, the E+/A ratio is still high. The particle identification in the RICH worked well, but the low efficiency of other detectors has prevented the extraction of physical results. The WA97 collaboration measures production of strange particles in lead-lead colli- sions at 160 A GeV/c. It is the first experiment to use silicon pixel detectors. The first lead-beam data were taken in the autumn of 1994. The analysis is not finished, but some preliminary results are available. NEXT PAGE(S) toft BLANK Acknowledgements I should like to thank the administration of Fysisk Institutt, Universitetet i Bergen, for providing an office and computer facilities, and the people of the nuclear physics group for creating a stimulating research environment. First and foremost I would like to thank my supervisor, Professor Gunnar L0vh0iden, and my group leader, Professor Tor Fredrik Thorsteinsen, for their support and advice, for their patience, and for all the help they provided when I was fed up with writing on my thesis. I would also like to thank Drs. Erling Andersen and Havard Helstrup for interesting discussions about physics and other subjects and for several nice walks in the Juras. I am grateful to Erling for help on computer problems and for reading a draft of my thesis and suggesting valuable improvements. I have highly appreciated the help from Havard in communicating with French speaking people and I have ignored his frequent hints about the nominal time needed to write a thesis. I am grateful to Dr. Larisa Bravina for several suggestions on theoretical papers I ought to read. It is a pleasure to thank the students in the nuclear physics groups in Bergen and Oslo, for enjoyable Student Seminars and for lots of fun during the Nordic conferences at Graftavallen and in Ronneby. I have appreciated all the questions from Kristin Fanebust, Tryggve Storas, J0rgen Lien, and Per Sennels, because they gave me lots of excuses to work in "interesting problems" instead of writing my thesis. I have enjoyed working in the WA85, WA94, and WA97 collaborations. I am grateful to the members of the collaborations for the work they have done in order to make these experiments successful. However, I will not mention everybody by name, since there were over 120 authors on the latest WA97 paper. I began my work in the collaborations as a summer student way back in 1989. I would like to thank my summer student supervisor, Dr. Emanuele Quercigh, for his continued support and valuable suggestions and for his ability to invent money. I was the first person from Bergen to work in WA85, and I would like to thank all the people who helped us join the collaboration in a smooth manner. I am grateful to the members of the group from the University of Birmingham, in particular, Professor John Kinson and Drs. Orlando Villalobos Baillie and David Evans, who introduced me to the world of detector hardware and on-line software, and arranged some entertaining barbecue parties. I gratefully acknowledge the help I have received from Drs. Federico Antinori, Domenico Elia, Adam Jacholkowski, Vassili Katchanov, Jean-Claude Lassalle, and Raymond Sene, during data taking and analysis, and when writing this thesis. I would also like to thank Dr. Kai Martens of the WA89 collaboration for teaching me how the RICH worked and how to set it up, and for some nice evenings in Geneva. iii This work was supported by Norges Allmennvitenskapelige Forskningsrad (grant 422.91 /013), Norges Forskningsrad (grant 100129/432), and Universitetet i Bergen ("avslut- ningsstipend" 94/3204). Additional financial support has been received from CERN, NATO, NorFA/Nordplus, Universitetet i Bergen, and Universitetet i Oslo. Finally, I am greatly indebted to my family and especially my parents and brothers for their continual love, support, and encouragement. Bergen, November 1995 Alv Kjetil Holme IV Contents Abstract i Acknowledgements iii Introduction 1 1 The Quark-Gluon Plasma and Relativistic Heavy-Ion Collisions 3 1.1 Quarks and Gluons 3 1.2 The QCD Phase Transition and the Quark-Gluon Plasma 5 1.3 Heavy-Ion Collisions 6 1.3.1 The language of high energy heavy-ion collisions 8 1.4 Signatures 9 1.4.1 Thermqdynamic variables 10 1.4.2 Chiral symmetry restoration 11 1.4.3 Colour response function 12 1.4.4 Electromagnetic signals 13 1.4.5 Exotica 14 1.5 Strangeness 14 1.5.1 Strangeness production 14 1.5.2 Particle ratios in a thermal model 16 1.6 Overview of Accelerators and Experiments 18 2 The WA85 Experiment 21 2.1 Experimental Setup 21 2.1.1 The Omega magnet 23 2.1.2 The beam 23 2.1.3 The beam counters 23 2.1.4 The target 23 2.1.5 The multiplicity microstrips 24 2.1.6 The A chambers 24 2.1.7 The hodoscopes 25 2.1.8 The Cerenkov detector 25 2.1.9 The calorimeter 26 2.1.10 The trigger 26 2.2 Data Analysis 26 2.2.1 Track finding 26 2.2.2 Finding V°s 27 2.2.3 Finding As 28 2.2.4 Finding charged Es 29 2.2.5 Finding fi" . : 31 2.2.6 Summary of raw particle yields 35 2.3 Corrections 36 2.4 Results 38 2.4.1 Transverse mass distributions 38 2.4.2 Particle ratios 39 2.5 Summary 40 The WA94 Experiment 41 3.1 Experimental Setup 41 3.1.1 The beam counters 41 3.1.2 The target 43 3.1.3 The multiplicity counters 43 3.1.4 The multiplicity microstrips 43 3.1.5 The A chambers in the 1991 run 43 3.1.6 The hadron calorimeter 43 3.1.7 The trigger in the 1991 run 45 3.1.8 The silicon telescope in the 1992 run 45 3.1.9 The iron wall in the 1992 run 46 3.1.10 The RICH in the 1992 run 46 3.1.11 The B chambers in the 1992 run 46 3.1.12 The trigger in the 1992 run 46 3.2 Data Analysis 47 3.3 Results 48 3.3.1 Transverse mass distributions 48 3.3.2 Particle ratios 48 3.4 Interpretation of the WA85 and WA94 Results 50 3.5 Summary 52 Particle Identification in the Omega RICH 53 4.1 The Ring Imaging Cerenkov Detector 53 4.1.1 Cerenkov radiation 53 4.1.2 Ring imaging 55 4.1.3 The Omega RICH 56 4.2 Track finding 61 4.2.1 Track finding in the silicon telescope 61 4.2.2 Track finding in the B chambers 61 4.2.3 Track matching 62 4.3 Analysis of the RICH Data 62 4.3.1 The RICH coordinate system 62 4.3.2 Alignment and calibration 63 4.3.3 Background pattern recognition 66 4.3.4 Ring finding and fitting 66 vi 4.3.5 Particle identification 66 4.4 Preliminary Results 72 4.5 Summary 72 5 The WA97 Experiment 75 5.1 Experimental Setup 75 5.2 Data Analysis and Preliminary Results 78 5.3 Summary 81 6 Summary and Outlook 83 A Published Papers 85 B The Butterfly Geometry 105 C Decay Kinematics 107 C.I Transverse momentum distribution of daughter particles from A decay . 107 C.2 The distance between cowboy and sailor crossings in a constant magnetic field 107 C.2.1 V° decay 107 C.2.2 Cascade decay 109 C.3 Podolanski-Armenteros plot 110 C.3.1 V° decay 110 C.3.2 Cascade, decay 112 D The Ring Imaging Geometry 115 D.I The deviation from the ideal impact point 116 References 119 NEXT PAGE(S) toft BLANK List of Figures 1.1 Effective quark-antiquark potential in QCD 4 1.2 Energy density and pressure as function of temperature in lattice QCD.
Recommended publications
  • The Role of Strangeness in Ultrarelativistic Nuclear

    The Role of Strangeness in Ultrarelativistic Nuclear

    HUTFT THE ROLE OF STRANGENESS IN a ULTRARELATIVISTIC NUCLEAR COLLISIONS Josef Sollfrank Research Institute for Theoretical Physics PO Box FIN University of Helsinki Finland and Ulrich Heinz Institut f ur Theoretische Physik Universitat Regensburg D Regensburg Germany ABSTRACT We review the progress in understanding the strange particle yields in nuclear colli sions and their role in signalling quarkgluon plasma formation We rep ort on new insights into the formation mechanisms of strange particles during ultrarelativistic heavyion collisions and discuss interesting new details of the strangeness phase di agram In the main part of the review we show how the measured multistrange particle abundances can b e used as a testing ground for chemical equilibration in nuclear collisions and how the results of such an analysis lead to imp ortant con straints on the collision dynamics and spacetime evolution of high energy heavyion reactions a To b e published in QuarkGluon Plasma RC Hwa Eds World Scientic Contents Introduction Strangeness Pro duction Mechanisms QuarkGluon Pro duction Mechanisms Hadronic Pro duction Mechanisms Thermal Mo dels Thermal Parameters Relative and Absolute Chemical Equilibrium The Partition Function The Phase Diagram of Strange Matter The Strange Matter Iglo o Isentropic Expansion Trajectories The T ! Limit of the Phase Diagram
  • Strange Particle Theory in the Cosmic Ray Period R

    Strange Particle Theory in the Cosmic Ray Period R

    STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD R. Dalitz To cite this version: R. Dalitz. STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD. Journal de Physique Colloques, 1982, 43 (C8), pp.C8-195-C8-205. 10.1051/jphyscol:1982811. jpa-00222371 HAL Id: jpa-00222371 https://hal.archives-ouvertes.fr/jpa-00222371 Submitted on 1 Jan 1982 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL DE PHYSIQUE Colloque C8, suppldment au no 12, Tome 43, ddcembre 1982 page ~8-195 STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD R.H. Dalitz Department of Theoretical Physics, 2 KebZe Road, Oxford OX1 3NP, U.K. What role did theoretical physicists play concerning elementary particle physics in the cosmic ray period? The short answer is that it was the nuclear forces which were the central topic of their attention at that time. These were considered to be due primarily to the exchange of pions between nucleons, and the study of all aspects of the pion-nucleon interactions was the most direct contribution they could make to this problem. Of course, this was indeed a most important topic, and much significant understanding of the pion-nucleon interaction resulted from these studies, although the precise nature of the nucleonnucleon force is not settled even to this day.
  • Detection of a Strange Particle

    Detection of a Strange Particle

    10 extraordinary papers Within days, Watson and Crick had built a identify the full set of codons was completed in forensics, and research into more-futuristic new model of DNA from metal parts. Wilkins by 1966, with Har Gobind Khorana contributing applications, such as DNA-based computing, immediately accepted that it was correct. It the sequences of bases in several codons from is well advanced. was agreed between the two groups that they his experiments with synthetic polynucleotides Paradoxically, Watson and Crick’s iconic would publish three papers simultaneously in (see go.nature.com/2hebk3k). structure has also made it possible to recog- Nature, with the King’s researchers comment- With Fred Sanger and colleagues’ publica- nize the shortcomings of the central dogma, ing on the fit of Watson and Crick’s structure tion16 of an efficient method for sequencing with the discovery of small RNAs that can reg- to the experimental data, and Franklin and DNA in 1977, the way was open for the com- ulate gene expression, and of environmental Gosling publishing Photograph 51 for the plete reading of the genetic information in factors that induce heritable epigenetic first time7,8. any species. The task was completed for the change. No doubt, the concept of the double The Cambridge pair acknowledged in their human genome by 2003, another milestone helix will continue to underpin discoveries in paper that they knew of “the general nature in the history of DNA. biology for decades to come. of the unpublished experimental results and Watson devoted most of the rest of his ideas” of the King’s workers, but it wasn’t until career to education and scientific administra- Georgina Ferry is a science writer based in The Double Helix, Watson’s explosive account tion as head of the Cold Spring Harbor Labo- Oxford, UK.
  • Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions

    Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions

    Available online at www.sciencedirect.com Nuclear Physics A 967 (2017) 760–763 www.elsevier.com/locate/nuclphysa Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions Isaac Upsal for the STAR Collaboration1 Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210 Abstract Collisions between heavy nuclei at ultra-relativistic energies form a color-deconfined state of matter known as the quark-gluon plasma. This state is well described by hydrodynamics, and non-central collisions are expected to produce a fluid characterized by strong vorticity in the presence of strong external magnetic fields. The STAR Collaboration at Brookhaven National Laboratory’s√ Relativistic Heavy Ion Collider (RHIC) has measured collisions between gold nuclei at center of mass energies sNN = 7.7 − 200 GeV. We report the first observation of globally polarized Λ and Λ hyperons, aligned with the angular momentum of the colliding system. These measurements provide important information on partonic spin-orbit coupling, the vorticity of the quark-gluon plasma, and the magnetic field generated in the collision. 1. Introduction Collisions of nuclei at ultra-relativistic energies create a system of deconfined colored quarks and glu- ons, called the quark-gluon plasma (QGP). The large angular momentum (∼104−5) present in non-central collisions may produce a polarized QGP, in which quarks are polarized through spin-orbit coupling in QCD [1, 2, 3]. The polarization would be transmitted to hadrons in the final state and could be detectable through global hyperon polarization. Global hyperon polarization refers to the phenomenon in which the spin of Λ (and Λ) hyperons is corre- lated with the net angular momentum of the QGP which is perpendicular to the reaction plane, spanned by pbeam and b, where b is the impact parameter vector of the collision and pbeam is the beam momentum.
  • Light Higgs Production in Hyperon Decay

    Light Higgs Production in Hyperon Decay

    Light Higgs Production in Hyperon Decay Xiao-Gang He∗ Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei. Jusak Tandean† Department of Mathematics/Physics/Computer Science, University of La Verne, La Verne, CA 91750, USA G. Valencia‡ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA (Dated: July 8, 2018) Abstract A recent HyperCP observation of three events in the decay Σ+ pµ+µ− is suggestive of a new particle → with mass 214.3 MeV. In order to confront models that contain a light Higgs boson with this observation, it is necessary to know the Higgs production rate in hyperon decay. The contribution to this rate from penguin-like two-quark operators has been considered before and found to be too large. We point out that there are additional four-quark contributions to this rate that could be comparable in size to the two-quark contributions, and that could bring the total rate to the observed level in some models. To this effect we implement the low-energy theorems that dictate the couplings of light Higgs bosons to hyperons at leading order in chiral perturbation theory. We consider the cases of scalar and pseudoscalar Higgs bosons in the standard model and in its two-Higgs-doublet extensions to illustrate the challenges posed by existing experimental constraints and suggest possible avenues for models to satisfy them. arXiv:hep-ph/0610274v3 16 Apr 2008 ∗Electronic address: [email protected] †Electronic address: [email protected] ‡Electronic address: [email protected] 1 I. INTRODUCTION Three events for the decay mode Σ+ pµ+µ− with a dimuon invariant mass of 214.3 0.5 MeV → ± have been recently observed by the HyperCP Collaboration [1].
  • Negative Strange Quark-Chemical Potential a Necessary and Sufficient Observable of the Deconfinement Phase Transition in a Finite-Baryon Equilibrated State*

    Negative Strange Quark-Chemical Potential a Necessary and Sufficient Observable of the Deconfinement Phase Transition in a Finite-Baryon Equilibrated State*

    Negative strange quark-chemical potential A necessary and sufficient observable of the deconfinement phase transition in a finite-baryon equilibrated state* Apostolos D. Panagiotou and Panayiotis Katsas University of Athens, Physics Department Nuclear & Particle Physics Division Panepistimiopolis, GR-157 71 Athens, Hellas Abstract We consider the variation of the strange quark-chemical potential in the phase diagramme of nuclear matter, employing the order parameters and mass-scaled partition functions in each domain and enforcing flavour conservation. Assuming the region beyond the hadronic phase to be described by massive, correlated and interacting quarks, in the spirit of lattice and N−J-L calculations, we find the strange quark-chemical potential to attain large negative values in this domain. We propose that this change in the sign of the strange quark- chemical potential, from positive in the hadronic phase to negative in the partonic, to be a unique, concise and well-defined indication of the quark-deconfinement phase transition in nuclear matter. We propose also that, for a chemically equilibrated state in the deconfined region, which follows an isentropic expansion to hadronization via a second order phase transition, the fugacities of the equilibrated quark flavours, once fixed in the primordial state, remain constant throughout the hadronization process. PACS codes: 25.75.+r,12.38.Mh,24.84.+p Key words: Quark-chemical potential, phase transition, deconfined quark matter, HG, QGP e-mail: [email protected] * Work supported in part by the Research Secretariat of the University of Athens. 1. Introduction It is generally expected that ultra-relativistic nucleus-nucleus collisions will provide the basis for strong interaction thermodynamics, which will lead to new physics.
  • The Mar (E) K of QGP: Strangeness

    The Mar (E) K of QGP: Strangeness

    The Mar(e)k of QGP: Strangeness∗ Jan Rafelski Department of Physics, The University of Arizona Tucson, AZ 85721, USA Strangeness signature of of quark-gluon plasma (QGP) is central to the exploration of baryon-dense matter: the search for the critical point and onset of deconfinement. I report on the discovery of QGP by means of strangeness: The key historical figures and their roles in this quest are introduced and the experimental results obtained are discussed. The im- portant role of antihyperons is emphasized. The statistical hadronization model, and sudden hadronization are described. Results of present day data analysis: strangeness and entropy content of a large fireball, and the universal hadronization condition describing key features of all explored collision systems are presented. PACS numbers: 25.75.-qRelativistic heavy-ion collisions 12.38.MhQuark-gluon plasma 24.10.PaThermal and statistical models 1. Introduction The introduction in 1964 of the new quark paradigm [1] `happened' nearly in parallel to the rise of the thermal model of hadron production pre- cipitated by Hagedorn's invention of the statistical bootstrap model, for a review of Hagedorn's work, see Ref. [2]. The paradigm of quarks explained a large number of properties of elementary particles, allowing at the time one prediction, a new particle, the triple-strange Ω−(sss). On the other hand Hagedorn was following fragmentary experimental data on particle produc- tion; these data were not in agreement with the rudimentary statistical arXiv:1701.00296v2 [hep-ph] 6 Feb 2017 particle production models proposed by Koppe [3] and Fermi [4]. Hage- dorn's work is a classic example of a discovery case where theory preceded experiment, focusing the direction of future experimental work.
  • Before Matter As We Know It Emerged, the Universe Was Filled with The

    Before Matter As We Know It Emerged, the Universe Was Filled with The

    Cambridge University Press 0521385369 - Hadrons and Quark–Gluon Plasma Jean Letessier and Johann Rafelski Frontmatter More information HADRONS AND QUARK–GLUON PLASMA Before matter as we know it emerged, the universe was filled with the primordial state of hadronic matter called quark–gluon plasma. This hot soup of quarks and gluons is effectively an inescapable consequence of our current knowledge about the fundamental hadronic interactions: quantum chromodynamics. This book covers the ongoing search to verify the prediction experimentally and discusses the physical properties of this novel form of matter. It provides an accessible introduction to the recent developments in this interdisciplinary field, covering the basics as well as more advanced material. It begins with an overview of the subject, followed by discussion of experimental methods and results. The second half of the book covers hadronic matter in confined and deconfined form, and strangeness as a signature of the quark–gluon phase. A firm background in quantum mechanics, special relativity, and statistical physics is assumed, as well as some familiarity with particle and nuclear physics. However, the essential introductory elements from these fields are presented as needed. This text is suitable as an introduction for graduate students, as well as pro- viding a valuable reference for researchers already working in this and related fields. JEAN LETESSIER has been CNRS researcher at the University of Paris since 1978. Prior to that he worked at the Institut de Physique Nucleaire, Orsay, where he wrote his thesis on hyperon–nucleon interaction in 1970, under the direction of Professor R. Vinh Mau, and was a teaching assistant at the University of Bordeaux.
  • Mass Generation Via the Higgs Boson and the Quark Condensate of the QCD Vacuum

    Mass Generation Via the Higgs Boson and the Quark Condensate of the QCD Vacuum

    Pramana – J. Phys. (2016) 87: 44 c Indian Academy of Sciences DOI 10.1007/s12043-016-1256-0 Mass generation via the Higgs boson and the quark condensate of the QCD vacuum MARTIN SCHUMACHER II. Physikalisches Institut der Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany E-mail: [email protected] Published online 24 August 2016 Abstract. The Higgs boson, recently discovered with a mass of 125.7 GeV is known to mediate the masses of elementary particles, but only 2% of the mass of the nucleon. Extending a previous investigation (Schumacher, Ann. Phys. (Berlin) 526, 215 (2014)) and including the strange-quark sector, hadron masses are derived from the quark condensate of the QCD vacuum and from the effects of the Higgs boson. These calculations include the π meson, the nucleon and the scalar mesons σ(600), κ(800), a0(980), f0(980) and f0(1370). The predicted second σ meson, σ (1344) =|ss¯, is investigated and identified with the f0(1370) meson. An outlook is given on the hyperons , 0,± and 0,−. Keywords. Higgs boson; sigma meson; mass generation; quark condensate. PACS Nos 12.15.y; 12.38.Lg; 13.60.Fz; 14.20.Jn 1. Introduction adds a small additional part to the total constituent- quark mass leading to mu = 331 MeV and md = In the Standard Model, the masses of elementary parti- 335 MeV for the up- and down-quark, respectively [9]. cles arise from the Higgs field acting on the originally These constituent quarks are the building blocks of the massless particles. When applied to the visible matter nucleon in a similar way as the nucleons are in the case of the Universe, this explanation remains unsatisfac- of nuclei.
  • Pentaquark and Tetraquark States Arxiv:1903.11976V2 [Hep-Ph]

    Pentaquark and Tetraquark States Arxiv:1903.11976V2 [Hep-Ph]

    Pentaquark and Tetraquark states 1 2 3 4;5 6;7;8 Yan-Rui Liu, ∗ Hua-Xing Chen, ∗ Wei Chen, ∗ Xiang Liu, y Shi-Lin Zhu z 1School of Physics, Shandong University, Jinan 250100, China 2School of Physics, Beihang University, Beijing 100191, China 3School of Physics, Sun Yat-Sen University, Guangzhou 510275, China 4School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China 5Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, Lanzhou 730000, China 6School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China 7Collaborative Innovation Center of Quantum Matter, Beijing 100871, China 8Center of High Energy Physics, Peking University, Beijing 100871, China April 2, 2019 Abstract The past seventeen years have witnessed tremendous progress on the experimental and theo- retical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in Ref. [1]. In this article, we shall update the experimental and theoretical efforts on the hidden heavy flavor multiquark systems in the past three years. Espe- cially the LHCb collaboration not only confirmed the existence of the hidden-charm pentaquarks but also provided strong evidence of the molecular picture. Besides the well-known XYZ and Pc states, we shall discuss more interesting tetraquark and pentaquark systems either with one, two, three or even four heavy quarks. Some very intriguing states include the fully heavy exotic arXiv:1903.11976v2 [hep-ph] 1 Apr 2019 tetraquark states QQQ¯Q¯ and doubly heavy tetraquark states QQq¯q¯, where Q is a heavy quark.
  • Charged Current Events with Neutral Strange Particles in High-Energy Antineutrino Interactions

    Charged Current Events with Neutral Strange Particles in High-Energy Antineutrino Interactions

    Nuclear Physics B177 (1981) 365-381 O North-Holland Publishing Company CHARGED CURRENT EVENTS WITH NEUTRAL STRANGE PARTICLES IN HIGH-ENERGY ANTINEUTRINO INTERACTIONS V.V. AMMOSOV, A.G. DENISOV, P.F. ERMOLOV, G.S. GAPIENKO, V.A. GAPIENKO, V.I. KLUKHIN, V.I. KORESHEV, P.V. PITUKHIN, V.I. SIROTENKO, E.A. SLOBODYUK, Z.V. USUBOV and V.G. ZAETZ Institute of High Energy Physics, Serpukhov, U$SR J.P. BERGE, D. BOGERT, R. ENDORF 1, R. HANFT, J.A. MALKO, G.I. MOFFATT 1, F.A. NEZRICK, R. ORAVA and J. WOLFSON Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA V.I. EFREMENKO, A.V. FEDOTOV, P.A. GORICHEV, V.S. KAFTANOV, G.K. KLIGER, V.Z. KOLGANOV, S.P. KRUTCHININ, M.A. KUBANTSEV, I.V. MAKHLJUEVA, V.I. SHEKELJAN and V.G. SHEVCHENKO Institute for Theoretical and Experimental Physics, MosCow, USSR J. BELL, C.T. COFFIN, B.P. ROE, A.A. SEIDL, D. SINCLAIR and E. WANG University of Michigan, Ann Arbor, Michigan 48104, USA Received 23 May 1980 (Revised 5 August 1980) The results of a study of strange particle production in charged current 77,N interactions in the Fermilab 15 ft bubble chamber filled with a heavy Ne-H2 mixture are presented. Production rates and average multiplicities of K°'s and A's as functions of W 2 and Q2 are given. The experimental data agree well with the quark-parton model predictions if a yield of 0.06 + 0.02 of K°'s and A's from charm production is included. Upper limits for D-meson production are given and the shape of the charmed quark fragmentation function is discussed.
  • The Quark Model and Deep Inelastic Scattering

    The Quark Model and Deep Inelastic Scattering

    The quark model and deep inelastic scattering Contents 1 Introduction 2 1.1 Pions . 2 1.2 Baryon number conservation . 3 1.3 Delta baryons . 3 2 Linear Accelerators 4 3 Symmetries 5 3.1 Baryons . 5 3.2 Mesons . 6 3.3 Quark flow diagrams . 7 3.4 Strangeness . 8 3.5 Pseudoscalar octet . 9 3.6 Baryon octet . 9 4 Colour 10 5 Heavier quarks 13 6 Charmonium 14 7 Hadron decays 16 Appendices 18 .A Isospin x 18 .B Discovery of the Omega x 19 1 The quark model and deep inelastic scattering 1 Symmetry, patterns and substructure The proton and the neutron have rather similar masses. They are distinguished from 2 one another by at least their different electromagnetic interactions, since the proton mp = 938:3 MeV=c is charged, while the neutron is electrically neutral, but they have identical properties 2 mn = 939:6 MeV=c under the strong interaction. This provokes the question as to whether the proton and neutron might have some sort of common substructure. The substructure hypothesis can be investigated by searching for other similar patterns of multiplets of particles. There exists a zoo of other strongly-interacting particles. Exotic particles are ob- served coming from the upper atmosphere in cosmic rays. They can also be created in the labortatory, provided that we can create beams of sufficient energy. The Quark Model allows us to apply a classification to those many strongly interacting states, and to understand the constituents from which they are made. 1.1 Pions The lightest strongly interacting particles are the pions (π).