DOCSLIB.ORG

Hunting for Exotic QQ ¯ Q ¯ Q Tetraquark States

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hunting for Exotic QQ ¯ Q ¯ Q Tetraquark States Hunting for exotic QQQ¯Q¯ tetraquark states Wei Chen Sun Yat-Sen University ICNFP 2017, Kolymbari, Crete, Greece August 17 { 26, 2017 Wei Chen QQQ¯Q¯ states August 23, 2017 1 / 25 Outline 1 Background of the exotic hadron states 2 Briefly Introduction of QCD Sum Rules 3 Moment sum rule analyses for mass spectra 4 Decay properties of the QQQ¯Q¯ tetraquarks 5 Summary Wei Chen QQQ¯Q¯ states August 23, 2017 2 / 25 Why hadron spectroscopy? Three generations of quarks: up, down, strange, charm, bottom, top. Hadrons are bound states of quarks, via strong interaction. The mass of the universe is mainly due to hadrons (95% are baryonic matter): nucleons forming nuclei! Wei Chen QQQ¯Q¯ states August 23, 2017 3 / 25 Why hadron spectroscopy? Quark masses only accounts for a small fraction of the nucleon mass: 99% is generated by dynamics of QCD confinement Light quark visible mass is dominated by QCD effects Hadron spectroscopy: revealing the nature of the hadron masses Quantitative understand the QCD confinement and spontaneous chiral symmetry breaking. Important for understanding the QCD vacuum. Wei Chen QQQ¯Q¯ states August 23, 2017 4 / 25 Exotic Hadrons in QCD meson(qq¯) baryon(qqq) Quark model is established to classify hadrons:JPC quantum numbers and flavour quantum numbers. However, the hadron structures are more complicated in QCD. It may allow for hadrons which lie outside the naive quark model. Mesons with exotic JPC quantum numbers: JPC = 0−−; 0+−; 1−+; 2+−; ::: Baryons with exotic flavour quantum numbers: dibaryon, pentaquark,... Wei Chen QQQ¯Q¯ states August 23, 2017 5 / 25 Different configurations of exotic hadrons: d u s u d c π u u s d u¯ u c c¯ c¯ dibaryon pentaquark molecule g c¯ u u¯ c q¯ q g g tetraquark glueball hybrid Wei Chen QQQ¯Q¯ states August 23, 2017 6 / 25 Overview of XYZ States Experiments: Belle, BaBar, BESIII, CLEO, D0, LHCb... s γ − − c γ e c e ∓ c c π γ * γ * c Y (4260) b c Z ± c c + + γ q q e c e J /ψ X (3872) Y (4260) X (3940) X (3915) Zc (3900) Y (4008) X (4160) Y (3940) X (4350) Zc (4025) Z + (4430) Y (4360) Z(3930) Zc (4020) Z + (4051) Y (4630) Zc (3885) Z + (4248) Y (4660) Y (4140) Y (4274) + Zc (4200) Z + (4240) X (3823) H.X.Chen, W.Chen, X.Liu, S.L.Zhu, Phys.Rept.639(2016) 1-121. Wei Chen QQQ¯Q¯ states August 23, 2017 7 / 25 Overview of XYZ States S. L. Olsen, Front. Phys. 10 (2015) 101401 Many charmonium-like states were discovered above the open-charm thresholds. Their masses and decay modes are different from the pure cc¯ charmonium states. Some charged Zc states were observed, which are evidences for four-quark states (ccu¯ d¯). They are good candidates for exotic hadron states! Wei Chen QQQ¯Q¯ states August 23, 2017 8 / 25 Theoretical Models Theoretical configurations: tetraquark, molecule, hybrid,... Zc states: tetraquark, molecule It is difficult to distinguish these two intepretations. c π u c d¯ c¯ ¯ c¯ u d Wei Chen QQQ¯Q¯ states August 23, 2017 9 / 25 Pentaquarks: Pc (4380) and Pc (4450) In 2015, LHCb reported two hidden-charm pentaquark states 800 Pc (4380) and Pc (4450) in J= p 700 (b) LHCb invariant mass distribution via 600 Λ0 J= K −p decay (PRL115, b 500 072001(2015)! ) Events/(15 MeV) 400 300 M1 = (4380 8 29) MeV ; ± ± 200 Γ1 = (205 18 86) MeV ; ± ± 100 M2 = (4449:8 1:7 2:5) MeV ; 0 ± ± 4 4.2 4.4 4.6 4.8 5 m [GeV] Γ2 = (39 5 19) MeV : J/ψp ± ± P 3 − 5 + 3 + 5 − 5 + 3 − J (Pc (4380); Pc (4450)) = 2 ; 2 ; 2 ; 2 or 2 ; 2 Wei Chen QQQ¯Q¯ states August 23, 2017 10 / 25 Pentaquarks: Pc (4380) and Pc (4450) Two possible configurations: ?? It is the time to search for more exotic multiquark states! Wei Chen QQQ¯Q¯ states August 23, 2017 11 / 25 Doubly hidden-flavor tetraquarks: QQQ¯Q¯ QQQ¯Q¯ Tetraquarks: They are far away from the mass range of the observed conventional qq¯ hadrons. Can be clearly distinguished experimentally from the normal states. The light mesons (π; ρ, !; σ...) can not be exchanged between two charmonia/bottomonia. The binding force comes from the short-range gluon exchange. A molecule configuration is not favored and thus the QQQ¯Q¯ is a good candidate for compact tetraquark. Q¯ Q ¯ Q Q Wei Chen QQQ¯Q¯ states August 23, 2017 12 / 25 Theoretical works: Quark-Gluon models: Prog. Theor. Phys. 54, 492 (1975); Zeit. Phys. C7, 317 (1981). Potential model: Phys.Rev. D25, 2370 (1982); Phys. Lett. B123, 449 (1983). MIT bag model: Phys. Rev. D32, 755 (1985). Hyperspherical harmonic formalism: Phys. Rev. D73, 054004 (2006). BS or Schroedinger Eqs: Phys.Rev.D86, 034004 (2012); Phys.Lett.B718, 545 (2012). Recent studies: arXiv:1605.01134; 1605.01647; 1612.00012; PRD95, 034011 (2017); EPJC77, 432 (2017); arXiv:1706.07553. Experiments: J= J= pairs: Phys. Lett. B707, 52 (2012) (LHCb); JHEP 1409, 094(2014) (CMS); Phys. Rev. D90, 111101 (2014) (D0). J= Υ(1S) events: Phys. Rev. Lett. 116, 082002 (2016) (D0); K. Dilsiz's talk at APS April Meeting 2016 on behalf of CMS, see https://absuploads.aps.org/presentation.cfm?pid=11931. Υ(1S)Υ(1S) pairs: JHEP 05, 013 (2017) (CMS). Wei Chen QQQ¯Q¯ states August 23, 2017 13 / 25 Tetraquark Sum Rules Study two-point correlation function of current J(x) with the same quantum numbers with hadron state: Z Π(q2) = i d4xeiq·x Ω T [J(x)Jy(0)] Ω h j j i Classify states X by coupling to current Ω J(x) X = 0 j i h j j i 6 Currents are probes of spectrum and might not overlap with state Interpolating currents with JPC = 0++: Q¯ Q T ¯ ¯T J1 = Qa Cγ5QbQaγ5CQb ; ¯ Q T ¯ µ ¯T Q J2 = Qa Cγµγ5QbQaγ γ5CQb ; T ¯ µν ¯T J3 = Qa CσµνQbQaσ CQb ; T ¯ µ ¯T J4 = Qa CγµQbQaγ CQb ; T ¯ ¯T J5 = Qa CQbQaCQb ; Wei Chen QQQ¯Q¯ states August 23, 2017 14 / 25 Hadron level: described by the dispersion relation N−1 (q2)N Z ImΠ(s) X Π(q2) = ds + b (q2)n; π sN (s q2 i) n − − n=0 1 X ρ(s) = ImΠ(s) = δ(s m2) 0 J n n Jy 0 π n n − h j j ih j j i = f 2δ(s m2 ) + continuum; X − X Quark-gluon level: evaluated via operator product expansion(OPE) Π(s) = Πpert (s) + ΠhGGi(s) + :::; Wei Chen QQQ¯Q¯ states August 23, 2017 15 / 25 Define moments in Euclidean region Q2 = q2 > 0: − n 2 1 d 2 Mn(Q0 ) = Π(Q ) Q2=Q2 n! − dQ2 j 0 Z 1 2 ρ(s) fX 2 = 2 ds = 2 2 1 + δn(Q0 ) ; 2 (s + Q )n+1 (m + Q )n+1 mH 0 X 0 2 where δn(Q0 ) contains the higher states and continuum. Ratio of the moments 2 2 2 Mn(Q0 ) 2 2 1 + δn(Q0 ) r(n; Q0 ) 2 = mX + Q0 2 : ≡ Mn+1(Q0 ) 1 + δn+1(Q0 ) Predict hadron mass q 2 2 mX = r(n; Q ) Q 0 − 0 2 2 for sufficiently large n when δn(Q0 ) ∼= δn+1(Q0 ) for convergence. Wei Chen QQQ¯Q¯ states August 23, 2017 16 / 25 Limitations for (n; ξ) parameter space: 2 2 ξ = Q0 =16mc ; for ccc¯c¯ system; 2 2 ¯¯ ξ = Q0 =mb; for bbbb system: Small ξ: higher dimensional condensates give large contributions to 2 Mn(Q0 ), leading to bad OPE convergence. 2 Large ξ: slower convergence of δn(Q0 ). This can be compensated by taking higher derivative n for the lowest lying resonance to dominate. Large n: moving further away from the asymptotically free region. The OPE convergence would also become bad. hGGi pert Requiring Π (s) Π (s) to obtain an upper limit nmax , which will increase with respect≤ to ξ. Good (n; ξ) region: the lowest lying resonance dominates the moments while the OPE series has good convergence. nmax = 75; 76; 77; 78 for ξ = 0:2; 0:4; 0:6; 0:8 Wei Chen QQQ¯Q¯ states August 23, 2017 17 / 25 H¨older'sinequality: 2 2 Mn(Q0 ) R = 2 2 1 ; Mr (Q0 )M2n−r (Q0 ) ≤ R 1.000 80 0.995 60 0.990 0 n 1 40 Ξ 2 20 3 The boundary gives( n; ξ) = (48; 0:2); (49; 0:4); (49; 0:6); (50; 0:8). Wei Chen QQQ¯Q¯ states August 23, 2017 18 / 25 Mass for scalar bbb¯b¯ tetraquark: mass curves have plateaus at (n; ξ) = (48; 0:2); (49; 0:4); (49; 0:6); (50; 0:8) 20.1 Ξ=0.2 19.7 Ξ=0.4 Ξ=0.6 D 19.3 Ξ=0.8 GeV @ X 18.9 m 18.5 18.45 18.1 12 20 28 36 44 52 60 68 76 n mX = (18:45 0:15) GeV: b ± Wei Chen QQQ¯Q¯ states August 23, 2017 19 / 25 Mass spectra for the ccc¯c¯ and bbb¯b¯ tetraquarks: PC J Currents mXc (GeV) mXb (GeV) ++ 0 J1 6:44 0:15 18:45 0:15 ± ± J2 6:59 0:17 18:59 0:17 ± ± J3 6:47 0:16 18:49 0:16 ± ± J4 6:46 0:16 18:46 0:14 ± ± J5 6:82 0:18 19:64 0:14 ± ± 1++ J+ 6:40 0:19 18:33 0:17 1µ ± ± J+ 6:34 0:19 18:32 0:18 2µ ± ± 1+− J− 6:37 0:18 18:32 0:17 1µ ± ± J+ 6:51 0:15 18:54 0:15 2µ ± ± ++ 2 J1µν 6:51 0:15 18:53 0:15 ± ± J2µν 6:37 0:19 18:32 0:17 ± ± −+ + 0 J1 6:84 0:18 18:77 0:18 J+ 6:85 ± 0:18 18:79 ±0:18 2 ± ± 0−− J− 6:84 0:18 18:77 0:18 1 ± ± 1−+ J+ 6:84 0:18 18:80 0:18 1µ ± ± J+ 6:88 0:18 18:83 0:18 2µ ± ± 1−− J− 6:84 0:18 18:77 0:18 1µ ± ± J− 6:83 0:18 18:77 0:16 2µ ± ± Wei Chen QQQ¯Q¯ states August 23, 2017 20 / 25 24.00 20.00 16.00 12.00 Mass (GeV) 8.00 4.00 0 + ++ ++ + ++ + 0− 0 1−− 1 1 − 2 0−− 1− Wei Chen QQQ¯Q¯ states August 23, 2017 21 / 25 Decay behavior: ccc¯c¯ tetraquarks ccc¯c¯ (ccq) + (¯cc¯q¯): kinematically forbidden.
Load more

Recommended publications
  • Fully Strange Tetraquark Sss¯S¯ Spectrum and Possible Experimental Evidence
    PHYSICAL REVIEW D 103, 016016 (2021) Fully strange tetraquark sss¯s¯ spectrum and possible experimental evidence † Feng-Xiao Liu ,1,2 Ming-Sheng Liu,1,2 Xian-Hui Zhong,1,2,* and Qiang Zhao3,4,2, 1Department of Physics, Hunan Normal University, and Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Changsha 410081, China 2Synergetic Innovation Center for Quantum Effects and Applications (SICQEA), Hunan Normal University, Changsha 410081, China 3Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China 4University of Chinese Academy of Sciences, Beijing 100049, China (Received 21 August 2020; accepted 5 January 2021; published 26 January 2021) In this work, we construct 36 tetraquark configurations for the 1S-, 1P-, and 2S-wave states, and make a prediction of the mass spectrum for the tetraquark sss¯s¯ system in the framework of a nonrelativistic potential quark model without the diquark-antidiquark approximation. The model parameters are well determined by our previous study of the strangeonium spectrum. We find that the resonances f0ð2200Þ and 2340 2218 2378 f2ð Þ may favor the assignments of ground states Tðsss¯s¯Þ0þþ ð Þ and Tðsss¯s¯Þ2þþ ð Þ, respectively, and the newly observed Xð2500Þ at BESIII may be a candidate of the lowest mass 1P-wave 0−þ state − 2481 0þþ 2440 Tðsss¯s¯Þ0 þ ð Þ. Signals for the other ground state Tðsss¯s¯Þ0þþ ð Þ may also have been observed in PC −− the ϕϕ invariant mass spectrum in J=ψ → γϕϕ at BESIII. The masses of the J ¼ 1 Tsss¯s¯ states are predicted to be in the range of ∼2.44–2.99 GeV, which indicates that the ϕð2170Þ resonance may not be a good candidate of the Tsss¯s¯ state.
    [Show full text]
  • Pos(LATTICE2014)106 ∗ [email protected] Speaker
    Flavored tetraquark spectroscopy PoS(LATTICE2014)106 Andrea L. Guerrieri∗ Dipartimento di Fisica and INFN, Università di Roma ’Tor Vergata’ Via della Ricerca Scientifica 1, I-00133 Roma, Italy E-mail: [email protected] Mauro Papinutto, Alessandro Pilloni, Antonio D. Polosa Dipartimento di Fisica and INFN, ’Sapienza’ Università di Roma P.le Aldo Moro 5, I-00185 Roma, Italy Nazario Tantalo CERN, PH-TH, Geneva, Switzerland and Dipartimento di Fisica and INFN, Università di Roma ’Tor Vergata’ Via della Ricerca Scientifica 1, I-00133 Roma, Italy The recent confirmation of the charged charmonium like resonance Z(4430) by the LHCb ex- periment strongly suggests the existence of QCD multi quark bound states. Some preliminary results about hypothetical flavored tetraquark mesons are reported. Such states are particularly amenable to Lattice QCD studies as their interpolating operators do not overlap with those of ordinary hidden-charm mesons. The 32nd International Symposium on Lattice Field Theory, 23-28 June, 2014 Columbia University New York, NY ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Flavored tetraquark spectroscopy Andrea L. Guerrieri 1. Introduction The recent confirmation of the charged resonant state Z(4430) by LHCb [1] strongly suggests the existence of genuine compact tetraquark mesons in the QCD spectrum. Among the many phenomenological models, it seems that only the diquark-antidiquark model in its type-II version can accomodate in a unified description the puzzling spectrum of the exotics [2]. Although diquark- antidiquark model has success in describing the observed exotic spectrum, it also predicts a number of unobserved exotic partners.
    [Show full text]
  • Physics Letters B 816 (2021) 136227
    Physics Letters B 816 (2021) 136227 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Scalar isoscalar mesons and the scalar glueball from radiative J/ψ decays ∗ A.V. Sarantsev a,b, I. Denisenko c, U. Thoma a, E. Klempt a, a Helmholtz–Institut für Strahlen– und Kernphysik, Universität Bonn, Germany b NRC “Kurchatov Institute”, PNPI, Gatchina 188300, Russia c Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow region, Russia a r t i c l e i n f o a b s t r a c t ¯ Article history: A coupled-channel analysis of BESIII data on radiative J/ψ decays into ππ, K K , ηη and ωφ has been Received 12 January 2021 performed. The partial-wave amplitude is constrained by a large number of further data. The analysis Received in revised form 16 March 2021 finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar Accepted 16 March 2021 mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states Available online xxxx are observed with significant yields only in the 1500-2100 MeV mass region. Singlet scalar mesons are Editor: M. Doser produced over a wide mass range but their yield peaks in the same mass region. The peak is interpreted = ± +10 = ± +30 as scalar glueball. Its mass and width are determined to M 1865 25−30 MeV and 370 50−20 MeV, − its yield in radiative J/ψ decays to (5.8 ± 1.0) 10 3. © 2021 The Author(s).
    [Show full text]
  • New Physics of Strong Interaction and Dark Universe
    universe Review New Physics of Strong Interaction and Dark Universe Vitaly Beylin 1 , Maxim Khlopov 1,2,3,* , Vladimir Kuksa 1 and Nikolay Volchanskiy 1,4 1 Institute of Physics, Southern Federal University, Stachki 194, 344090 Rostov on Don, Russia; [email protected] (V.B.); [email protected] (V.K.); [email protected] (N.V.) 2 CNRS, Astroparticule et Cosmologie, Université de Paris, F-75013 Paris, France 3 National Research Nuclear University “MEPHI” (Moscow State Engineering Physics Institute), 31 Kashirskoe Chaussee, 115409 Moscow, Russia 4 Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia * Correspondence: [email protected]; Tel.:+33-676380567 Received: 18 September 2020; Accepted: 21 October 2020; Published: 26 October 2020 Abstract: The history of dark universe physics can be traced from processes in the very early universe to the modern dominance of dark matter and energy. Here, we review the possible nontrivial role of strong interactions in cosmological effects of new physics. In the case of ordinary QCD interaction, the existence of new stable colored particles such as new stable quarks leads to new exotic forms of matter, some of which can be candidates for dark matter. New QCD-like strong interactions lead to new stable composite candidates bound by QCD-like confinement. We put special emphasis on the effects of interaction between new stable hadrons and ordinary matter, formation of anomalous forms of cosmic rays and exotic forms of matter, like stable fractionally charged particles. The possible correlation of these effects with high energy neutrino and cosmic ray signatures opens the way to study new physics of strong interactions by its indirect multi-messenger astrophysical probes.
    [Show full text]
  • Discovery Potential for the Lhcb Fully Charm Tetraquark X(6900) State Via P¯P Annihilation Reaction
    PHYSICAL REVIEW D 102, 116014 (2020) Discovery potential for the LHCb fully charm tetraquark Xð6900Þ state via pp¯ annihilation reaction † ‡ Xiao-Yun Wang,1,* Qing-Yong Lin,2, Hao Xu,3 Ya-Ping Xie,4 Yin Huang,5 and Xurong Chen4,6,7, 1Department of physics, Lanzhou University of Technology, Lanzhou 730050, China 2Department of Physics, Jimei University, Xiamen 361021, China 3Department of Applied Physics, School of Science, Northwestern Polytechnical University, Xi’an 710129, China 4Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China 5School of Physical Science and Technology, Southwest Jiaotong University, Chendu 610031, China 6University of Chinese Academy of Sciences, Beijing 100049, China 7Guangdong Provincial Key Laboratory of Nuclear Science, Institute of Quantum Matter, South China Normal University, Guangzhou 510006, China (Received 2 August 2020; accepted 16 November 2020; published 18 December 2020) Inspired by the observation of the fully-charm tetraquark Xð6900Þ state at LHCb, the production of Xð6900Þ in pp¯ → J=ψJ=ψ reaction is studied within an effective Lagrangian approach and Breit-Wigner formula. The numerical results show that the cross section of Xð6900Þ at the c.m. energy of 6.9 GeV is much larger than that from the background contribution. Moreover, we estimate dozens of signal events can be detected by the D0 experiment, which indicates that searching for the Xð6900Þ via antiproton-proton scattering may be a very important and promising way. Therefore, related experiments are suggested to be carried out. DOI: 10.1103/PhysRevD.102.116014 I. INTRODUCTION Γ ¼ 168 Æ 33 Æ 69 MeV; ð2Þ In recent decades, more and more exotic hadron states have been observed [1].
    [Show full text]
  • Observation of Structure in the J/Ψ-Pair Mass Spectrum
    EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-EP-2020-115 LHCb-PAPER-2020-011 CERN-EP-2020-115June 30, 2020 22 June 2020 Observation of structure in the J= -pair mass spectrum LHCb collaborationy 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. Submitted to Science Bulletin c 2020 CERN for the benefit of the LHCb collaboration. CC BY 4.0 licence. yAuthors are listed at the end of this paper. ii 1 1 Introduction 2 The strong interaction is one of the fundamental forces of nature and it governs the 3 dynamics of quarks and gluons. According to quantum chromodynamics (QCD), the 4 theory describing the strong interaction, quarks are confined into hadrons, in agreement 5 with experimental observations. The quark model [1,2] classifies hadrons into conventional 6 mesons (qq) and baryons (qqq or qqq), and also allows for the existence of exotic hadrons 7 such as tetraquarks (qqqq) and pentaquarks (qqqqq).
    [Show full text]
  • Deciphering the Recently Discovered Tetraquark Candidates Around 6.9 Gev
    Eur. Phys. J. C (2021) 81:25 https://doi.org/10.1140/epjc/s10052-020-08818-7 Regular Article - Theoretical Physics Deciphering the recently discovered tetraquark candidates around 6.9 GeV Jacob Sonnenschein1,a, Dorin Weissman2,b 1 The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel 2 Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan Received: 6 October 2020 / Accepted: 28 December 2020 © The Author(s) 2021 Abstract Recently a novel hadronic state of mass 6.9 GeV, or, using a second fitting model that decays mainly to a pair of charmonia, was observed in [ ( )]= ± ± LHCb. The data also reveals a broader structure centered M X 6900 6886 11 11 around 6490 MeV and suggests another unconfirmed reso- [X(6900)]=168 ± 33 ± 69 (1.2) nance centered at around 7240 MeV, very near to the thresh- The data also reveals a broader structure centered around old of two doubly charmed cc baryons. We argue in this note that these exotic hadrons are genuine tetraquarks and 6490 MeV, referred to as a “threshold enhancement” in [1], not molecules of charmonia. It is conjectured that they are and also suggests the existence of another resonance centered V-baryonium , namely, have an inner structure of a baryonic at around 7240 MeV,very near to the threshold of two doubly vertex with a cc diquark attached to it, which is connected by charmed cc baryons. See Fig. 1. The higher state, which we ( ) a string to an anti-baryonic vertex with a c¯c¯ anti-diquark.
    [Show full text]
  • Model-Independent Evidence for Exotic Hadron Contributions To#[Subscript B][Superscript 0]→J/#Pπ−Decays
    Model-Independent Evidence for Exotic Hadron Contributions to#[subscript b][superscript 0]→J/#pπ−Decays The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Aaij, R., C. Abellán Beteta, B. Adeva, M. Adinolfi, Z. Ajaltouni, S. Akar, J. Albrecht, et al. "Model-Independent Evidence for Exotic Hadron Contributions toΛ[subscript b][superscript 0]→J/ψpπ−Decays." Physical Review Letters 117, 082002 (August 2016): 1-9 © 2016 CERN for the LHCb Collaboration As Published http://dx.doi.org/10.1103/PhysRevLett.117.082002 Publisher American Physical Society Version Final published version Citable link http://hdl.handle.net/1721.1/110294 Terms of Use Creative Commons Attribution Detailed Terms http://creativecommons.org/licenses/by/3.0 week ending PRL 117, 082002 (2016) PHYSICAL REVIEW LETTERS 19 AUGUST 2016 0 − Model-Independent Evidence for J=ψp Contributions to Λb → J=ψpK Decays R. Aaij et al.* (LHCb Collaboration) (Received 19 April 2016; published 18 August 2016) 0 − The data sample of Λb → J=ψpK decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1, is inspected for the presence of J=ψp or J=ψK− contributions with minimal assumptions about K−p contributions. It is demonstrated at more than 0 − − nine standard deviations that Λb → J=ψpK decays cannot be described with K p contributions alone, and that J=ψp contributions play a dominant role in this incompatibility. These model-independent results þ support the previously obtained model-dependent evidence for Pc → J=ψp charmonium-pentaquark states in the same data sample.
    [Show full text]
  • Scalar Tetraquark Candidates on the Lattice
    Scalar tetraquark candidates on the lattice Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften vorgelegt beim Fachbereich Physik der Johann Wolfgang Goethe-Universität in Frankfurt am Main von Joshua Berlin Frankfurt am Main 2017 D30 vom Fachbereich Physik der Johann Wolfgang Goethe-Universität als Dissertation angenommen. Dekan: Prof. Dr. O. Philipsen Gutachter: Prof. Dr. M. Wagner Prof. Dr. C. Alexandrou Datum der Disputation: Contents Deutsche Zusammenfassung vii 1 Introduction1 2 QCD on the lattice5 2.1 The classical theory . .5 2.2 Lattice gauge action . .7 2.3 Wilson fermions . .8 2.4 Path integrals from the lattice . 12 2.4.1 Fermion contraction . 12 2.4.2 Gauge field Configurations . 13 2.5 Correlation functions . 16 2.6 Towards the continuum . 17 2.6.1 Infinite volume limit . 17 2.6.2 Continuum limit . 17 2.6.3 Chiral limit . 18 2.7 Setting the scale . 19 3 Meson spectroscopy 21 3.1 Multi-particle correlators . 21 3.2 The variational method . 23 3.3 Interpolating operators . 26 3.3.1 Four-quark interpolators . 27 3.4 Techniques for propagator computation . 32 3.4.1 Point-to-all propagators . 33 3.4.2 Stochastic timeslice-to-all propagators . 34 3.4.3 The one-end trick . 36 3.4.4 Sequential propagators . 37 3.5 Smearing Techniques . 39 3.5.1 Gauge link smearing . 39 3.5.2 Smeared quark sources and sinks . 40 iii iv Contents 4 Technical aspects 41 4.1 Simulation details . 41 4.1.1 Fixing a charm quark mass . 42 4.2 Computation of the correlation matrix .
    [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]
  • The Quantum Chromodynamics Theory of Tetraquarks and Mesomesonic Particles Unfinished Draft Version
    The Quantum Chromodynamics Theory Of Tetraquarks And Mesomesonic Particles Unfinished draft version Based on a generalized particle diagram of baryons and anti-baryons which, in turn, is based on symmetry principles, this theory predicts the existence of all the tetraquarks and dimeson molecules (mesomesonic particles) there exist in nature. by R. A. Frino Electronics Engineer - Degree from the University of Mar del Plata. March 4th, 2016 (v1) Keywords: mirror symmetry, parity, P symmetry, charge conjugation, C symmetry, time reversal, T symmetry, CP symmetry, CPT symmetry, PC+ symmetry, Q symmetry, quantum electrodynamics, quantum chromodynamics, quark, antiquark, up quark, down quark, strange quark, charm quark, bottom quark, top quark, anti-up quark, anti-down quark, anti-strange quark, anti-charm quark, anti-bottom quark, anti-top quark, tetraquark, pentaquark, antitetraquark, non-strange tetraquark, colour charge, anticolour, anticolour charge, strangeness, charmness, bottomness, topness, fermion, hadron, baryon, meson, boson, photon, gluon, mesobaryonic particle, meso-baryonic particle, mesobaryonic molecule, meso-mesonic molecule, meso-mesonic particle, dimeson particle, dimeson molecule, Pauli exclusion principle, force carrier, omega- minus particle, matter-antimatter way, quadruply flavoured tetraquark, MAW, MMP, MMM, LHC. (see next page) The Quantum Chromodynamics Theory Of Tetraquarks And Mesomesonic Particles - v1. Copyright © 2016 Rodolfo A. Frino. All rights reserved. 1 1. Introduction Quantum Chromodynamics (QCD) [1, 2, 3, 4] is a quantum mechanical description of the strong nuclear force. The strong force is mediated by gluons [4, 5] which are spin 1ℏ bosons (spin is quoted in units of reduced Plank's constant: ℏ =h/2π ). Gluons act on quarks only (only quarks feel the strong force).
    [Show full text]
  • Tetraquark Spectroscopy: a Symmetry Analysis
    Symmetry 2009, 1, 155-179; doi:10.3390/sym1020155 OPEN ACCESS symmetry ISSN 2073-8994 www.mdpi.com/journal/symmetry Article Tetraquark Spectroscopy: A Symmetry Analysis Javier Vijande 1;¤ and Alfredo Valcarce 2 1 Departamento de F´ısica Atomica,´ Molecular y Nuclear, Universidad de Valencia (UV) and IFIC (UV-CSIC), Valencia, Spain 2 Departamento de F´ısica Fundamental, Universidad de Salamanca, Salamanca, Spain; E-Mail: [email protected] ? Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +34-963543883. Received: 23 October 2009 / Accepted: 13 November 2009 / Published: 23 November 2009 Abstract: We present a detailed analysis of the symmetry properties of a four-quark wave function and its solution by means of a variational approach for simple Hamiltonians. We discuss several examples in the light and heavy-light meson sector. Keywords: Hadron spectroscopy; group theory 1. Introduction The potentiality of the quark model for hadron physics in the low-energy regime became first manifest when it was used to classify the known hadron states. Describing hadrons as qq¹ or qqq configurations, their quantum numbers were correctly explained. This assignment was based on the comment by Gell-Mann [1] introducing the notion of quark: “It is assuming that the lowest baryon configuration (qqq) gives just the representations 1, 8 and 10, that have been observed, while the lowest meson configuration (qq¹) similarly gives just 1 and 8”. Since then, it has been assumed that these are the only two configurations involved in the description of physical hadrons. However, color confinement is also compatible with other multiquark structures like the tetraquark qqq¹q¹ first introduced by Jaffe [2].
    [Show full text]