DOCSLIB.ORG

Lhcb Results on Penta(Tetra)-Quark Search

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lhcb Results on Penta(Tetra)-Quark Search LHCb results on penta(tetra)-quark search Marcin Kucharczyk1 (on behalf of the LHCb collaboration) 1Henryk Niewodniczanski Institute of Nuclear Physics PAN, Krakow, Poland E-mail: [email protected] (Received October 17, 2016) The LHCb experiment is designed to study the properties and decays of heavy flavored hadrons produced in pp collisions at the LHC. The data collected in the LHC Run I enables precision spec- troscopy studies of beauty and charm hadrons. The latest results on spectroscopy of conventional and exotic hadrons are reviewed, such as the discovery of the first charmonium pentaquark states in the J/ψp system or the confirmation of resonant nature of the Z(4430)− mesonic state. LHCb has also made significant contributions to determination of the quantum numbers for the X(3872) state and to exclude the existence of the X(5568) tetraquark candidate. The LHCb results described in the present document have dramatically increased the interest on spectroscopy of heavy hadrons. KEYWORDS: pentaquarks, heavy flavor spectroscopy, exotic states 1. Introduction In the simple quark model, only two types of quark combinations are required to account for the existing hadrons, i.e. qq¯ combinations form mesons, while baryons are made up of three quarks. How- ever, in the quark model proposed by Gell-Mann and Zweig in 1960s [1] other SU(3) color-neutral combinations of quarks and gluons such as gg glueballs, qqg¯ hybrids, qqq¯ q¯ tetraquarks,qqqqq ¯ pen- taquarks etc. were predicted. The world’s largest data sample of beauty and charm hadrons collected by LHCb during LHC Run I provides great opportunities for studying the production and properties of heavy hadrons. Since such exotic states are experimentally hard to find in the light quark sector, the first discovery of the narrow exotic tetraquark state X(3872) by the Belle collaboration [2] was made only in 2003, leading to a revolution in the exotic hadron spectroscopy. Up to now several other exotic states have been observed, all involving heavy quark systems. The LHCb experiment has al- ready collected an impressive set of results on exotic heavy flavour states, with the first unambiguous spin-parity assignments of the X(3872) [3], confirmation of resonant nature of the Z(4430)− [4] or ob- + + Λ0 → − servation of two resonant states, Pc(4380) and Pc(4450) in the decay b J/ψpK [5], which are consistent with charmonium pentaquarks. The present document describes some recent results from LHCb in exotic hadron spectroscopy. For all the studies the LHCb data corresponding to 3 fb−1of integrated luminosity in 7 and 8 TeV pp collisions has been used. 2. Pentaquark candidates in Λ0 → J/ψpK− b Λ0 → − −1 First observation of the b J/ψpK with 1 f b had unexpected large yield. It was orig- Λ0 ± inally used to precisely measure the b lifetime [6]. The sample of 26,007 166 signal candidates subtracted of 5.4% background candidates within ±15 MeV of the J/ψK− p mass peak has been se- lected using full Run I dataset. An anomalous peaking structure in the J/ψp invariant mass spectrum might be observed on the Dalitz plot shown in Fig. 1. Since the contribution of Λ∗ → K− p reso- 2 nances corresponding to the vertical bands only dominates the low mKp region, it is unlikely that the 1.
Load more

Recommended publications
  • Observation of Structure in the J/Ψ-Pair Mass Spectrum
    EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-EP-2020-115 LHCb-PAPER-2020-011 November 10, 2020 Observation of structure in the J= -pair mass spectrum LHCb collaboration† Abstract p Using proton-proton collision data at centre-of-mass energies of s = 7, 8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb−1, the invariant mass spectrum of J= pairs is studied. A narrow structure around 6:9 GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J= mass are observed. The deviation of the data from nonresonant J= -pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit{Wigner lineshape. arXiv:2006.16957v2 [hep-ex] 10 Nov 2020 Keywords: QCD; exotics; tetraquark; spectroscopy; quarkonium; particle and resonance production Published in Science Bulletin 2020 65(23)1983-1993 © 2020 CERN for the benefit of the LHCb collaboration. CC BY 4.0 licence. †Authors are listed at the end of this paper. ii 1 Introduction The strong interaction is one of the fundamental forces of nature and it governs the dynamics of quarks and gluons. According to quantum chromodynamics (QCD), the theory describing the strong interaction, quarks are confined into hadrons, in agreement with experimental observations. The quark model [1,2] classifies hadrons into conventional mesons (qq) and baryons (qqq or qqq), and also allows for the existence of exotic hadrons such as tetraquarks (qqqq) and pentaquarks (qqqqq).
    [Show full text]
  • Slides Lecture 1
    Advanced Topics in Particle Physics Probing the High Energy Frontier at the LHC Ulrich Husemann, Klaus Reygers, Ulrich Uwer University of Heidelberg Winter Semester 2009/2010 CERN = European Laboratory for Partice Physics the world’s largest particle physics laboratory, founded 1954 Historic name: “Conseil Européen pour la Recherche Nucléaire” Lake Geneva Proton-proton2500 employees, collider almost 10000 guest scientists from 85 nations Jura Mountains 8.5 km Accelerator complex Prévessin site (approx. 100 m underground) (France) Meyrin site (Switzerland) Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 2 Large Hadron Collider: CMS Experiment: Proton-Proton and Multi Purpose Detector Lead-Lead Collisions LHCb Experiment: B Physics and CP Violation ALICE-Experiment: ATLAS Experiment: Heavy Ion Physics Multi Purpose Detector Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 3 The Lecture “Probing the High Energy Frontier at the LHC” Large Hadron Collider (LHC) at CERN: premier address in experimental particle physics for the next 10+ years LHC restart this fall: first beam scheduled for mid-November LHC and Heidelberg Experimental groups from Heidelberg participate in three out of four large LHC experiments (ALICE, ATLAS, LHCb) Theory groups working on LHC physics → Cornerstone of physics research in Heidelberg → Lots of exciting opportunities for young people Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 4 Scope
    [Show full text]
  • Department of High Energy Physics: Overview
    DEPARTMENT OF HIGH ENERGY PHYSICS 93 6 DEPARTMENT OF HIGH ENERGY PHYSICS PLO401707 Head of Department: Assoc. Professor Helena Balkowska phone: (22) 621-28-04 e-mail: Lena.Bialkowskafuw.edu.pl Overview The activities of the Department f Hgh Energy Physics are centered around experiments performed at accelerators in the following laboratories: • At CERN, the European Laboratory for Particle Physics in Geneva, Switzerland: DELPHI* at LEP ee- stora(Te rina - the tests of the Standard Model, b-quark physics, gamina-gami-na interactions and search for Higgs boson and supersymmetric particles - NA48 - the CP-violation and are K decays - COMPASS (Compact Muon and Proton Apparatus for Structure and Spectroscopy) - studies the gluon polarization in the nucleon - NA49* and WA98 - heavy ion physics, looking for possible effects of the phase transition to te quark- - gluon plasma state • At CELSIUS Storage Ring in Uppsala, Sweden: - WASA - a precise study of near threshold resonance poduction. • At RHIC - study of pp elastic scatterin.g. • At DESY in Hamburg, Germany: - ZEUS - deep inelastic scattering f elections and protons, proton structure functions, dffractive poton- proton interactions. • Super-Karniokande and K2K - a study of neutrino oscillations. The Groups fi-om our Department participated in the construction phase of te experiments, both in hardware and in development of the software used in data analysis. Presently they take part in te data collection, detector performance supervision and data analysis. The Department is also involved
    [Show full text]
  • Photon Detectors for the Ring Imaging Cherenkov Counters of the Lhcb Experiment
    Photon Detectors for the Ring Imaging Cherenkov Counters of the LHCb Experiment Richard W. R. Plackett Imperial College, London A thesis submitted for the degree of Doctor of Philosophy in the University of London July 2006 c R. Plackett 2006 ABSTRACT This thesis reports on the author’s contribution to the development of the Ring Imaging Cherenkov(RICH) detectors in the LHCb experiment due to take data at the CERN Large Hadron Collider in 2007. The first chapter summarises the physics to be explored by the LHCb experiment; measurements of CP violating asymmetries and a study of rare B decay modes. A brief overview of other experiments studying B-physics is presented. The experiment itself is then described, focussing on the RICH system used for particle identification, with particular emphasis on the photon detectors. The thesis then reports on the work done by the author on the design of the RICH1 Magnetic Shield, that allows the photon detectors to operate in the fringe field of the LHCb dipole magnet, while fulfilling the conflicting requirement to provide additional magnetic bending power to aid the LHCb charged particle trigger. The design of all of the many sections of the shield are described in depth and the results of finite element simulations performed by the author are reported. The results of measurements the author took of the field produced by the completed magnetic shield are then evaluated and compared with the simulation. Next follows a study undertaken by the author on the electronic readout of the RICH Hybrid Photon Detectors (HPD). Two related mesurments were made, a novel series of timing tests on the HPD’s analogue readout in an assembled tube and a series of experiments using a pulsed laser to simulate the charge deposition of a photoelectron.
    [Show full text]
  • Study and Design of the Readout Unit Module for the Lhcb Experiment CERN-THESIS-2002-036 31/12/2001 José Francisco Toledo Alarcón
    Study and Design of the Readout Unit Module for the LHCb Experiment CERN-THESIS-2002-036 31/12/2001 José Francisco Toledo Alarcón Under the direction of Dr. Francisco José Mora Más Doctoral Thesis Electronics Engineering Department Universidad Politécnica de Valencia, 2001 To Hans, with gratitude. I couldn’t have got this far without your experience, support and leading. i List of acronyms xi Preface 1 Introduction 1 Objectives 2 Thesis structure 4 Contributions by other engineers and physicists 6 CHAPTER 1 Data acquisition in high-energy physics experiments 9 Particle accelerators 9 Particle detectors 11 Particle detector readout 12 Evolution of DAQ systems 13 Instrumentation buses for HEP in the 60’s and in the 70’s 14 DAQ and trigger systems in the 80’s 16 New trends in the 90’s 18 Trends in DAQ systems for the 21st century 20 The PCI Flexible I/O Card (PCI-FLIC) 22 Conclusions 24 CHAPTER 2 DAQ and Trigger systems in LHCb 27 The LHCb experiment at CERN 27 LHC: A new accelerator for new physics 27 A Large Hadron Collider Beauty Experiment (LHCb) 28 Front-end electronics overview 30 LHCb trigger and DAQ architecture 31 Trigger system 32 Data Acquisition (DAQ) system 34 Flow control in LHCb 35 CHAPTER 3 The Readout Unit for the LHCb experiment 39 Target applications in the LHCb experiment 39 The Readout Unit as input stage to the LHCb DAQ system 40 The Readout Unit as Front-end Multiplexer for the Level-1 Electronics 43 The Readout Unit as readout module for the Level-1 Vertex Locator Trigger 45 Design criteria and parameters 47 DAQ Readout
    [Show full text]
  • The Aim of the Lhcb Experiment 1 at the Large Hadron Collider at CERN Is to Perform Precise Tests of the Standard Model (SM) In
    Latest results from LHCb on B�s) ---+µµ and other very rare decays A. Sarti on behalf of the LHCb collaboration Rome University "La Sapienza", Department of Basic and applied sciences for engineering, Via Antonio Scarpa 14/16, 00161 Roma, Italy In this review I present the latest updates on the searches for very rare decays to muonic final states performed within the LHCb collaboration using pp collisions at 7 and 8 TeV centre of mass energy. Flavour changing neutral current processes, such as K� µ+ µ-, - - - Bf,) -+ µ+µ and Bf,) -+ µ+ µ µ+µ are highly suppressed in the Standard Model (SM) and arc therefore excellent probes of New Physics (NP) processes or heavy particles---+ that can significantly modify the expected SM rates. Out of the many interesting results obtained by the LHCb collaboration in the study of rare decays, this review covers in detail the searches for K� -+ µ+µ-, B� -+ µ+µ-and Bf,) -+ µ+µ-µ+µ-decays and the first evidence for the B� -+ µ+µ-decay. 1 Introduction The aim of the LHCb experiment 1 at the Large Hadron Collider at CERN is to performprecise tests of the Standard Model (SM) in the flavour sector, in order to disentangle possible New Physics (NP) effects. While the direct evidence of NP processes, like the measurement of the masses and properties of new particles, will provide an indisputable proof of existence, the accurate analysis of the transitions occurring in the flavour sector can be a powerful discovery tool, in scenarios where the NP energy scale is not completely decoupled from theflavour one.
    [Show full text]
  • Observation of Structure in the -Pair Mass Spectrum
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2020 Observation of structure in the J/ψ-pair mass spectrum LHCb Collaboration ; Bernet, R ; Müller, K ; Owen, P ; Serra, N ; Steinkamp, O ; et al DOI: https://doi.org/10.1016/j.scib.2020.08.032 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-196709 Journal Article Published Version The following work is licensed under a Creative Commons: Attribution 4.0 International (CC BY 4.0) License. Originally published at: LHCb Collaboration; Bernet, R; Müller, K; Owen, P; Serra, N; Steinkamp, O; et al (2020). Observation of structure in the J/ψ-pair mass spectrum. Science Bulletin, 2020:65. DOI: https://doi.org/10.1016/j.scib.2020.08.032 Science Bulletin 65 (2020) 1983–1993 Contents lists available at ScienceDirect Science Bulletin journal homepage: www.elsevier.com/locate/scib Article Observation of structure in the J/w-pair mass spectrum LHCb collaboration 1 article info abstract Article history: Using proton-proton collision data at centre-of-mass energies of ps 7; 8 and 13 TeV recorded by the ffiffi ¼ 1 Received 1 July 2020 LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fbÀ , the Received in revised form 28 July 2020 invariant mass spectrum of J/w pairs is studied. A narrow structure around 6:9 GeV=c2 matching the line- Accepted 19 August 2020 shape of a resonance and a broad structure just above twice the J/w mass are observed.
    [Show full text]
  • Lambda and Anti-Labmda Production in the ALICE Experiment at the LHC
    LLNL-TR-643836 Lambda and Anti-Labmda production in the ALICE experiment at the LHC. R. Carmona, R. Soltz September 12, 2013 Disclaimer This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Strangeness Production in Jets with ALICE at the LHC Rodney Carmona, Mike Tyler II, Ron Soltz, Austin Harton, Edmundo Garcia Chicago State University, Lawrence Livermore National Laboratory Cern (European Organization for Nuclear Research) At this laboratory Physicists and Engineers study fundamental particles using the world’s largest and most complex instruments. Here particles are made to collide at close to the speed of light to see how they interact and help to discover the basic laws of nature.
    [Show full text]
  • Test of Lepton Universality in Beauty-Quark Decays
    EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-EP-2021-042 LHCb-PAPER-2021-004 23 March 2021 Test of lepton universality in beauty-quark decays LHCb collaboration† Abstract The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton-proton collision data collected with the LHCb detector at CERN's Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the Standard Model, such as a new fundamental interaction between quarks arXiv:2103.11769v1 [hep-ex] 22 Mar 2021 and leptons. Submitted to Nature Physics © 2021 CERN for the benefit of the LHCb collaboration. CC BY 4.0 licence. †Authors are listed at the end of this paper. ii The Standard Model (SM) of particle physics provides precise predictions for the properties and interactions of fundamental particles, which have been confirmed by numerous experiments since the inception of the model in the 1960's. However, it is clear that the model is incomplete. The SM is unable to explain cosmological observations of the dominance of matter over antimatter, the apparent dark-matter content of the Universe, or explain the patterns seen in the interaction strengths of the particles.
    [Show full text]
  • LHC@Home Status BOINC Workshop 2013, Grenoble
    LHC@home status BOINC workshop 2013, Grenoble Nils Høimyr & Pete Jones, on behalf the LHC@home team at CERN CERN IT Department CH-1211 Genève 23 Switzerland www.cern.ch/it Contents ● Introduction, CERN and the LHC ● Status of LHC@home – LHC@home Classic - SixTrack – LHC@home VM - Test4Theory – Beauty@LHC - B-physics for LHCb experiment – Other activities around volunteer computing – New LHC@home Web portal – Plans for BOINC server consoldiation – BOINC issues/wish list – Questions CERN IT Department CH-1211 Genève 23 Switzerland www.cern.ch/it PESCERN was founded 1954: 12 European States “Science for Peace” Today: 20 Member States ~ 2300 staff ~ 1050 other paid personnel > 11000 users Budget (2012) ~1000 MCHF Member States: Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom Candidate for Accession: Romania Associate Members in the Pre-Stage to Membership: Israel, Serbia Applicant States: Cyprus, Slovenia, Turkey Observers to Council: India, Japan, the Russian Federation, the United CERN IT Department CH-1211 Genève 23 States of America, Turkey, the European Commission and UNESCO Switzerland www.cern.ch/it 3 LHC accelerator and experiments LHCb CMS ATLAS Exploration of a new energy frontier in p-p and Pb-Pb collisions ALICE LHC ring: 27 km circumference CERN IT Department CH-1211 Genève 23 Switzerland www.cern.ch/it The LHC Data Challenge •The accelerator will run for 20 years •Experiments
    [Show full text]
  • "Status of the Lhcb Experiment"
    StatusStatusStatus ofofof thethethe LHCbLHCbLHCb ExperimentExperimentExperiment o Introduction o Detector Status – VELO – RICH – ECAL – Trigger o Physics o Conclusions Beauty 2000 Sea of Galilee Franz Muheim 13. 9. 2000 University of Edinburgh DedicationDedication Tom Ypsilantis o conceived RICH detectors 1928 - 2000 in 1977 (with J. Seguinot) o a founding member of LHCb, totally dedicated to the RICH project o a colleague always eager to discuss new ideas o was a good friend for many of us o He will be missed Sea of Galilee, 13. 9. 2000 Beauty 2000 2 IntroductionIntroduction o CPV only observed in UnitarityTrianglesUnitarityTriangles neutral kaon system Vud Vub* + Vcd Vcb* + Vtd Vtb* = 0 – theoretical uncertainties o Standard Model – 3 generation CKM matrix allows for CPV if h¹0 – predicts large CPV asymmetries for B mesons o No real understanding Vud* Vtd + Vus* Vts + Vub* Vtb = 0 – Baryogenesis: additional source of CPV needed arg Vub = -g arg Vtd = -b – why is strong CPV small? arg Vts = p+ dg Ô New physics around the corner? Sea of Galilee, 13. 9. 2000 Beauty 2000 3 inin BB MesonMeson SystemSystem o Ideal to search for new physics Peskin, EPS 1999 o SM makes accurate predictions – precision tests o CPV in many decays – consistency o Examples – Vub & BB-mixing – sin 2b & sin 2a – g & dg with Bs mesons – compare to kaon sector eK & K-> pnn o Can extract parameters of SM and new physics Sea of Galilee, 13. 9. 2000 Beauty 2000 4 LargeLarge HadronHadron ColliderCollider o By 2005: BABAR, BELLE, CLEO-III, CDF, D0, HERA-B Ô 1st test of CKM matrix (r,h) vs sin 2b o LHCb is a 2nd generation experiment Ô precision measurements of CP overconstrain CKM elements LHCLHC Ô large statistics, Bs mesons o LHC is the most intensive source of B mesons (Bd, Bu, Bs, Bc) – sbb = 500 mb sinelastic = 80 mb 32 -2 -1 – Luminosity <L>LHCb = 2 x10 cm s 34 -2 -1 <L>LHC = 10 cm s Ô 1012 bb / 107 s Sea of Galilee, 13.
    [Show full text]
  • Upgrade of the Global Muon Trigger for the Compact Muon Solenoid Experiment at CERN
    DISSERTATION/DOCTORAL THESIS Titel der Dissertation/Title of the Doctoral Thesis “Upgrade of the Global Muon Trigger for the Compact Muon Solenoid experiment at CERN” verfasst von/submitted by Mag. Dinyar Sebastian Rabady angestrebter akademischer Grad/in partial fulfilment of the requirements for the degree of Doktor der Naturwissenschaften (Dr. rer. nat.) CERN-THESIS-2018-033 25/04/2018 Wien, im Jänner 2018/Vienna, in January 2018 Studienkennzahl lt. Studienblatt/ A 796 605 411 degree programme code as it appears on the student record sheet: Studienrichtung lt. Studienblatt/ Physik field of study as it appears onthe student record sheet: Betreut von/Supervisor: Dipl.-Ing. Dr. Claudia-Elisabeth Wulz Hon.-Prof. Dipl.-Phys. Dr. Eberhard Widmann Für meinen Großvater. Abstract The Large Hadron Collider is a large particle accelerator at the CERN research labo- ratory, designed to provide particle physics experiments with collisions at unprece- dented centre-of-mass energies. For its second running period both the number of colliding particles and their collision energy were increased. To cope with these more challenging conditions and maintain the excellent performance seen during the first running period, the Level-1 trigger of the Compact Muon Solenoid experiment — a so- phisticated electronics system designed to filter events in real-time — was upgraded. This upgrade consisted of the complete replacement of the trigger electronics andafull redesign of the system’s architecture. While the calorimeter trigger path now follows a time-multiplexed processing model where the entire trigger data for a collision are received by a single processing board, the muon trigger path was split into regional track finding systems where each newly introduced track finder receives data from all three muon subdetectors for a certain geometric detector slice and reconstructs fully formed muon tracks from this.
    [Show full text]