DOCSLIB.ORG

Measurement of Parton Distributions of Strange Quarks from Charged

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measurement of Parton Distributions of Strange Quarks from Charged 102 Annual Report 2008 Measurement of Parton Distributions of Strange Quarks from Charged-kaon Production in Deep-inelastic Scattering on the Deuteron* by W.Augustyniak, B.Maria Lski, A.Trzci Lski, P. aupra Lski [I.4] Parton distribution functions (PDFs) form the basis to the kinematic requirements:Q 2#1GeV 2, for the description of the flavor structure of the W2#10GeV 2 and y $0.85, where -Q 2 is the squared nucleon. The spin-averaged parton distribution four momentum of the virtual photon, W is the functions q(x), of quarks and antiquarks of flavors invariant mass of the photon-nucleon system, and q=(u,d,s) describe the quark momentum distributions, y= */E with * being the photon energy and E the where x is the dimensionless Bjorken scaling variable positron beam energy. The Bjorken x range of representing the momentum fraction carried by the measurement was 0.02 "0.6. The spin averaged PDFs parton in a frame where the target has “infinite” for the strange quarks were determined from the shape longitudinal momentum. They are the sums of the and magnitude of the measured yield of charged kaons number densities of the quarks with the same and for the two beam-target polarization states. The results opposite helicity as that of the nucleon. The are presented in Fig. 1. differences or helicity distributions, denoted here by ! describe the flavor dependent contributions of the quark spins to the spin of the nucleon. The features of the parton distributions reflect the QCD dynamics of the constituents. Because strange quarks are objects which reflect directly properties of the nucleon sea, they are of special interest. Their distributions are also important because of their impact on quantitative calculations of certain key short-distance processes at hadron colliders, and their implications for the Fig. 1 The multiplicity (corrected for spectrometer acceptance) of charged kaons from a deuterium target, as a function of the Bjorken measurement of the Weinberg angle in deep-inelastic scaling variable x. The solid curve is the result of the HERMES scattering (DIS) of neutrinos. analysis. The dashed (dash-dotted) curve is the nonstrange (strange) Much of the information on properties of the quark contribution to the multiplicity for this fit. The dotted curve is the best fit obtained using previously assumed strange quark PDFs. helicity distribution of strange quarks is based on the The error bars are statistical. The band represents the systematic analysis of inclusive DIS and hyperon decay under the uncertainties. The values of (Q 2) for each x bin are shown in the assumption of SU(3) symmetry among the structures lower panel. of the octet baryons. Now for the first time the Hermes In the absence of experimental data for strange experiment has made a direct measurement of the quarks it has been customary to assume that the shape strange quark PDFs. To probe the flavor of of the strange quark PDFs is the average of that for the strangeness one detects, in coincidence with the up and down quarks. Attempts to fit the HERMES scattered lepton, charged K mesons which contain data using this assumption (see dotted curve in Fig. 1) strange and anti-strange quarks. do not provide a reasonable fit to the observed multiplicity curve. However, by taking the strange We report here on a new isoscalar extraction of quark PDF as an unknown, using known values for the s(x)+s "(x) and (s(x)+s "(x)) from polarized DIS on a up and down quark PDFs together with known values deuterium target. The data were recorded with a for the fragmentation functions which describe the longitudinally nuclear polarized gas target internal to conversion of the struck quark into the final kaon, it the E=27.6 GeV HERA positron storage ring at was possible to obtain a good fit to the data. The DESY. The self-induced beam polarization was improved fit (solid curve in Fig. 1) is an indication measured continuously by Compton back scattering of that the actual distribution is substantially different circularly polarized laser beams. The open-ended from those of the nonstrange quarks. target cell was fed by an atomic-beam source based on Stern-Gerlach separation with hyperfine transitions. The differences of the measured multiplicities for The nuclear polarization of the atoms was flipped at the two beam-target polarization states yielded the 90s time intervals, while both this polarization and the helicity distribution of the strange quarks. The results atomic fraction inside the target cell were indicate that, within experimental uncertainty, the continuously measured. The average value of the strange quarks are unpolarized and make no deuteron polarization was 0.845 with a fractional contribution to the spin of the proton. Furthermore, in systematic uncertainty of 3.5%. large measure the strange sea is generated by gluons conversion into quark-antiquark pairs. Consequently, Scattered beam leptons and coincident hadrons the HERMES result suggests that the gluons in the were detected by the HERMES spectrometer. Leptons proton are themselves not strongly polarized. were identified with an efficiency exceeding 98% and * a hadron contamination of less than 1%. A ring- The HERMES collaboration comprises 32 imaging Cerenkov (RICH) detector was used to institutions from 11 countries at the Deutsches identify charged kaons. Events were selected subject Elektronen Synchrotron (DESY) in Hamburg .
Load more

Recommended publications
  • The Particle World
    The Particle World ² What is our Universe made of? This talk: ² Where does it come from? ² particles as we understand them now ² Why does it behave the way it does? (the Standard Model) Particle physics tries to answer these ² prepare you for the exercise questions. Later: future of particle physics. JMF Southampton Masterclass 22–23 Mar 2004 1/26 Beginning of the 20th century: atoms have a nucleus and a surrounding cloud of electrons. The electrons are responsible for almost all behaviour of matter: ² emission of light ² electricity and magnetism ² electronics ² chemistry ² mechanical properties . technology. JMF Southampton Masterclass 22–23 Mar 2004 2/26 Nucleus at the centre of the atom: tiny Subsequently, particle physicists have yet contains almost all the mass of the discovered four more types of quark, two atom. Yet, it’s composite, made up of more pairs of heavier copies of the up protons and neutrons (or nucleons). and down: Open up a nucleon . it contains ² c or charm quark, charge +2=3 quarks. ² s or strange quark, charge ¡1=3 Normal matter can be understood with ² t or top quark, charge +2=3 just two types of quark. ² b or bottom quark, charge ¡1=3 ² + u or up quark, charge 2=3 Existed only in the early stages of the ² ¡ d or down quark, charge 1=3 universe and nowadays created in high energy physics experiments. JMF Southampton Masterclass 22–23 Mar 2004 3/26 But this is not all. The electron has a friend the electron-neutrino, ºe. Needed to ensure energy and momentum are conserved in ¯-decay: ¡ n ! p + e + º¯e Neutrino: no electric charge, (almost) no mass, hardly interacts at all.
    [Show full text]
  • 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.
    [Show full text]
  • Strange Jet Tagging
    1 Strange Jet Tagging Yuichiro Nakai T. D. Lee Institute & Shanghai Jiao Tong U. Based on YN, D. Shih and S. Thomas, 2003.09517 [hep-ph]. Higgs and Flavor, EF02, Snowmass, August 2020 2 Jets at colliders Jet : collimated bunch of hadrons as the signatures of quarks and gluons produced in high-energy collisions ✓ QCD partons are never observed isolated due to confinement. ✓ They give cascades of radiation (parton shower) by QCD processes. ✓ Hadrons are formed at ∼ ΛQCD Understanding jets is a key ingredient of physics measurements and new physics searches at colliders. What initial parton produces a jet ? 3 Quark and Gluon Tagging Top quark Gluon S. Yang, talk slide More constituents with more uniform Jet mass, N-subjettiness, … energy fragmentation and wider. Bottom/Charm Up-type vs Down-type Look for a displaced pT -weighted jet charge (secondary) vertex. 1 Qi Q (p j )κ κ = jet κ ∑ j T (pT ) j∈jet Wikipedia The last missing piece : Strange quark tagging? 4 Tagging Strategy • Strange vs Gluon We can expect the same thing as quark/gluon discrimination. S. Yang, talk slide More constituents with more uniform • Strange vs Up energy fragmentation and wider. We can expect the same thing as up/down discrimination. pT -weighted jet charge 1 Qi = Q (p j )κ κ (p jet )κ ∑ j T • Strange vs Down T j∈jet Possible ?? Main theme of Both are quarks with the same charge. this talk 5 Tagging Strategy CMS experiment at the LHC Tracker : trajectories of charged particles ECAL : energy of electrons and photons HCAL : energy deposits of hadrons 6 Tagging Strategy
    [Show full text]
  • Charm and Strange Quark Contributions to the Proton Structure
    Report series ISSN 0284 - 2769 of SE9900247 THE SVEDBERG LABORATORY and \ DEPARTMENT OF RADIATION SCIENCES UPPSALA UNIVERSITY Box 533, S-75121 Uppsala, Sweden http://www.tsl.uu.se/ TSL/ISV-99-0204 February 1999 Charm and Strange Quark Contributions to the Proton Structure Kristel Torokoff1 Dept. of Radiation Sciences, Uppsala University, Box 535, S-751 21 Uppsala, Sweden Abstract: The possibility to have charm and strange quarks as quantum mechanical fluc- tuations in the proton wave function is investigated based on a model for non-perturbative QCD dynamics. Both hadron and parton basis are examined. A scheme for energy fluctu- ations is constructed and compared with explicit energy-momentum conservation. Resulting momentum distributions for charniand_strange quarks in the proton are derived at the start- ing scale Qo f°r the perturbative QCD evolution. Kinematical constraints are found to be important when comparing to the "intrinsic charm" model. Master of Science Thesis Linkoping University Supervisor: Gunnar Ingelman, Uppsala University 1 kuldsepp@tsl .uu.se 30-37 Contents 1 Introduction 1 2 Standard Model 3 2.1 Introductory QCD 4 2.2 Light-cone variables 5 3 Experiments 7 3.1 The HERA machine 7 3.2 Deep Inelastic Scattering 8 4 Theory 11 4.1 The Parton model 11 4.2 The structure functions 12 4.3 Perturbative QCD corrections 13 4.4 The DGLAP equations 14 5 The Edin-Ingelman Model 15 6 Heavy Quarks in the Proton Wave Function 19 6.1 Extrinsic charm 19 6.2 Intrinsic charm 20 6.3 Hadronisation 22 6.4 The El-model applied to heavy quarks
    [Show full text]
  • Strangeness Content of the Pion in the U(3) Nambu-Jona-Lasinio Model
    Strangeness content of the pion in the U(3) Nambu-Jona-Lasinio model F´abioL. Braghin Instituto de F´ısica,Federal University of Goias, Av. Esperan¸ca,s/n, 74690-900, Goi^ania,GO, Brazil September 6, 2021 Abstract The Nambu-Jona-Lasinio model is considered with flavor-dependent coupling constants ¯ ¯ ¯ ¯ 2 Gij ( λi )( λj ) + ( iγ5λi )( iγ5λj ) for i; j = 0; 1::Nf − 1, and Nf = 3. A self consistent calculation of quark effective masses and coupling constants is performed making the strange quark effective mass to vary considerably. Quantum mechanical mixings between up, down and strange constituent quarks yields a strangeness content of the light u and d quarks constituent and of the pions. DIfferent estimates for the strangeness contribution for the pion mass are provided. 1 Introduction Hadron structure involves a large number of degrees of freedom and intrincated phenomena. Consequently their description with analytical methods in Quantum Chromodynamics presents many difficulties that usually require some approximative schemes being also possible to resort to effective models usually valid within a range of a variable, usually energy, associated to some physical scale. In spite of the limitations of an effective model, when compared to first principles calculations, one might expect that improvements eventually may produce a framework hoppefully comparable to effective field theories (EFT) if fundamental properties of QCD are taken into account by introducing the correct degrees of freedom in a suitable and correct way. Besides that, effective models can show very clearly the main connections between observables and the corresponding relevant degrees of freedom. The quark-level Nambu-Jona-Lasinio model (NJL) arXiv:2108.02748v2 [hep-ph] 3 Sep 2021 [1, 2, 3] captures some important features of quark dynamics and it has shown to be appropriate to describe several aspects of hadrons whenever Dynamical Chiral Symmetry Breaking (DChSB) plays an important role.
    [Show full text]
  • Quarks and Their Discovery
    Quarks and Their Discovery Parashu Ram Poudel Department of Physics, PN Campus, Pokhara Email: [email protected] Introduction charge (e) of one proton. The different fl avors of Quarks are the smallest building blocks of matter. quarks have different charges. The up (u), charm They are the fundamental constituents of all the (c) and top (t) quarks have electric charge +2e/3 hadrons. They have fractional electronic charge. and the down (d), strange (s) and bottom (b) quarks Quarks never exist alone in nature. They are always have charge -e/3; -e is the charge of an electron. The found in combination with other quarks or antiquark masses of these quarks vary greatly, and of the six, in larger particle of matter. By studying these larger only the up and down quarks, which are by far the particles, scientists have determined the properties lightest, appear to play a direct role in normal matter. of quarks. Protons and neutrons, the particles that make up the nuclei of the atoms consist of quarks. There are four forces that act between the quarks. Without quarks there would be no atoms, and without They are strong force, electromagnetic force, atoms, matter would not exist as we know it. Quarks weak force and gravitational force. The quantum only form triplets called baryons such as proton and of strong force is gluon. Gluons bind quarks or neutron or doublets called mesons such as Kaons and quark and antiquark together to form hadrons. The pi mesons. Quarks exist in six varieties: up (u), down electromagnetic force has photon as quantum that (d), charm (c), strange (s), bottom (b), and top (t) couples the quarks charge.
    [Show full text]
  • 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.
    [Show full text]
  • Masses of Scalar and Axial-Vector B Mesons Revisited
    Eur. Phys. J. C (2017) 77:668 DOI 10.1140/epjc/s10052-017-5252-4 Regular Article - Theoretical Physics Masses of scalar and axial-vector B mesons revisited Hai-Yang Cheng1, Fu-Sheng Yu2,a 1 Institute of Physics, Academia Sinica, Taipei 115, Taiwan, Republic of China 2 School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, People’s Republic of China Received: 2 August 2017 / Accepted: 22 September 2017 / Published online: 7 October 2017 © The Author(s) 2017. This article is an open access publication Abstract The SU(3) quark model encounters a great chal- 1 Introduction lenge in describing even-parity mesons. Specifically, the qq¯ quark model has difficulties in understanding the light Although the SU(3) quark model has been applied success- scalar mesons below 1 GeV, scalar and axial-vector charmed fully to describe the properties of hadrons such as pseu- mesons and 1+ charmonium-like state X(3872). A common doscalar and vector mesons, octet and decuplet baryons, it wisdom for the resolution of these difficulties lies on the often encounters a great challenge in understanding even- coupled channel effects which will distort the quark model parity mesons, especially scalar ones. Take vector mesons as calculations. In this work, we focus on the near mass degen- an example and consider the octet vector ones: ρ,ω, K ∗,φ. ∗ ∗0 eracy of scalar charmed mesons, Ds0 and D0 , and its impli- Since the constituent strange quark is heavier than the up or cations. Within the framework of heavy meson chiral pertur- down quark by 150 MeV, one will expect the mass hierarchy bation theory, we show that near degeneracy can be quali- pattern mφ > m K ∗ > mρ ∼ mω, which is borne out by tatively understood as a consequence of self-energy effects experiment.
    [Show full text]
  • Quark Masses 1 66
    66. Quark masses 1 66. Quark Masses Updated August 2019 by A.V. Manohar (UC, San Diego), L.P. Lellouch (CNRS & Aix-Marseille U.), and R.M. Barnett (LBNL). 66.1. Introduction This note discusses some of the theoretical issues relevant for the determination of quark masses, which are fundamental parameters of the Standard Model of particle physics. Unlike the leptons, quarks are confined inside hadrons and are not observed as physical particles. Quark masses therefore cannot be measured directly, but must be determined indirectly through their influence on hadronic properties. Although one often speaks loosely of quark masses as one would of the mass of the electron or muon, any quantitative statement about the value of a quark mass must make careful reference to the particular theoretical framework that is used to define it. It is important to keep this scheme dependence in mind when using the quark mass values tabulated in the data listings. Historically, the first determinations of quark masses were performed using quark models. These are usually called constituent quark masses and are of order 350MeV for the u and d quarks. Constituent quark masses model the effects of dynamical chiral symmetry breaking discussed below, and are not directly related to the quark mass parameters mq of the QCD Lagrangian of Eq. (66.1). The resulting masses only make sense in the limited context of a particular quark model, and cannot be related to the quark mass parameters, mq, of the Standard Model. In order to discuss quark masses at a fundamental level, definitions based on quantum field theory must be used, and the purpose of this note is to discuss these definitions and the corresponding determinations of the values of the masses.
    [Show full text]
  • Higgs Bosons with Large Couplings to Light Quarks
    YITP-SB-19-25 Higgs bosons with large couplings to light quarks Daniel Egana-Ugrinovic1;2, Samuel Homiller1;3 and Patrick Meade1 1C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, New York 11794, USA 2Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada 3Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA Abstract A common lore has arisen that beyond the Standard Model (BSM) particles, which can be searched for at current and proposed experiments, should have flavorless or mostly third-generation interactions with Standard Model quarks. This theoretical bias severely limits the exploration of BSM phenomenology, and is especially con- straining for extended Higgs sectors. Such limitations can be avoided in the context of Spontaneous Flavor Violation (SFV), a robust and UV complete framework that allows for significant couplings to any up or down-type quark, while suppressing flavor- changing neutral currents via flavor alignment. In this work we study the theory and phenomenology of extended SFV Higgs sectors with large couplings to any quark generation. We perform a comprehensive analysis of flavor and collider constraints of extended SFV Higgs sectors, and demonstrate that new Higgs bosons with large arXiv:1908.11376v2 [hep-ph] 31 Dec 2019 couplings to the light quarks may be found at the electroweak scale. In particular, we find that new Higgses as light as 100 GeV with order ∼ 0.1 couplings to first- or second-generation quarks, which are copiously produced at the LHC via quark fusion, are allowed by current constraints. Furthermore, the additional SFV Higgses can mix with the SM Higgs, providing strong theory motivation for an experimental program looking for deviations in the light quark{Higgs couplings.
    [Show full text]
  • THE STRANGE QUARK GLUON PLASMA Johann Rafelski
    621 THE STRANGE QUARK GLUON PLASMA Johann Rafelski", U. Heinzb, J. Letessierc, J. Sollfrankb and A. Tounsic "Department of Physics, University of Arizona, Tucson, AZ 85721 binstitut fiir Theoretische Physik der Universitiit,D-93040 Regensburg CLPTHE, Universite Paris 7, Tour 24, 5e et, 2 Place Jussieu, F-75251 CEDEX 05 ABSTRACT The mechanisms producing the strange quark flavor in high energy nuclear collisions are discussed and a dynamical picture developed for the build up of strangeness. The parameters characterizing strangeness phase space population are discussed and are related to measurable quantities. Circumstantial evidence for the formation of the deconfined phase (quark- gluon plasma, QGP) is presented, based on anomalous strange antibaryon abundances seen. It is argued that further experimental data will make the identificationof QGP definitive. 1. STRANGENESS AS AN OBSERVABLE OF QGP: Finding uncompromising signs of the transitory presence of the Quark-Gluon Plasma phase in the debris of the high energy nuclear collision has become the obsessive preoccupation of the high energy heavy ion theorists. The idea to use for this purpose the strange particles is not new and in the past dozen years strange particle production in heavy ion collisions and in particular their importance as diagnostic tool has been discussed a few times already at Rencontres de Moriond [l]; in the past 18 months considerable progress has occurred which allows us to return to the topic again, both in this report and in the parallel presentation of U. Heinz [2]. In order to appreciate these developments in full it is necessary to recall that the dynamical processes of strangeness production were from the beginning recognized as an essential element in the understanding of the high density matter in the central fireball.
    [Show full text]
  • Muon Bundles from the Universe* Maciej Rybczyński Institute of Physics, Jan Kochanowski University, Kielce, Poland
    Muon bundles from the Universe* Maciej Rybczyński Institute of Physics, Jan Kochanowski University, Kielce, Poland 17th International Conference on Strangeness in Quark Matter 10-15 July 2017 Utrecht, the Netherlands *based on P. Kankiewicz, MR, G. Wilk, and Z. Włodarczyk, ApJ 839 (2017) 31 [arXiv:1612.04749] Introduction ✓ Cosmic rays (CR) are particles coming from the Galaxy or outside the Galaxy reaching the Earth’s atmosphere. ✓ 90% protons, 9% He nuclei, 1% heavier nuclei ✓ Gammas, neutrinos ✓ Rate ~1000 particles hits the atmosphere per m2s CR are characterized by: ✓ Identity of the particle ✓ Energy (109 – 1020 eV) ✓ All arrival directions Cosmic ray physics with CERN experiments ✓Small detectors with respect to EAS experimets ✓ Low underground ✓ Detection of muons (only!) crossing the rock ✓ Short time of data taking These detectors are not designed to cosmic ray physics! Advantages: ▪ Detectors with very high performance ▪ Presence of magnetic field Detection of CR by CERN LEP experiments ALEPH: 130 m of rock, momentum muon threshold p > 70/cosθ ✓ underground scintillators, HCAL (horizontal area ~ 50 m2 ), TPC projected area ~ 16 m2 DELPHI: 100 m of rock, momentum muon threshold p > 52/cosθ ✓ Hadron calorimeter (horizontal area ~ 75 m2), muon barrel, TPC, ToF and outer detectors L3+C: 30 m of rock, momentum muon threshold p > 20/cosθ + surface array ✓ Scintillator surface array (200 m2), trigger, muon barrel (100 m2), hadron calorimeter, etc. COSMIC RAY ENERGY COVERAGE FROM 1014 – 1018 eV LEP results: muon multiplicity spectra ✔ These muon bundles are not well described (more than an order of magnitude above ALEPH: V. Avati et al., Astr. Phys.
    [Show full text]