DOCSLIB.ORG

Exotic Hadron Searches in Photoproduction GHP2021

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Exotic Hadron Searches in Photoproduction GHP2021 Exotic hadron searches in photoproduction GHP2021 Astrid N. Hiller Blin [email protected] P C J A Phys. Rev. D100 (2019) 034010 1907.09393 [hep-ph] Phys. Rev. D102 (2020) 114010 2008.01001 [hep-ph] April 16, 2021 The family of exotics • Since 2003: discovery of many new unexpected resonance candidates in hadron colliders • E.g. mesons whose PC cannot be matched by content ( ) J qq¯ π1 Guo et al., 1912.07030 • XYZ states Brambilla et al., 1907.07583 Hosaka et al., 1603.09229 • Baryons with exotic flavor content, e.g. positive strangeness or negative charm • Pentaquarks, di-baryons, gluonium, quark-gluon hybrids, … q q q g q q q¯ g g q g q q q g g g g g g q q q g g g q • Lepton beams provide efficient probes of the hadron spectrum, due to their point-like nature, free of kinematical effects from 3-body dynamics • Independent confirmation • Limited statistics so far at COMPASS and JLab (not yet seen in photoproduction): promising for searches with higher-luminosity in electron-ion colliders! A. N. Hiller Blin GHP2021 April 16th, 2021 2 XYZ photoproduction dynamics • t-channel exchanges assumed to give leading contributions • Fixed spin near threshold: full s dependence, but asymptotically sj (exceeds unitarity bound) • Reggeization at high energies: tower of particles with increasing spin • Couplings determined from known experimental branching fractions • VMD assumed for determination of top couplings γ Q V efV α1⋯αj β1⋯βj ! < λ�λN′ |T |λγλN > = � �α ⋯α ;β ⋯β ℬ ! q ∑ λV=λγ,λ� 1 j 1 j λN λN′ q0 mV T V, ℰ k E j−M α(t)−M j −iπα(t) p p0 4 p(t) q(t) dμμ′(! θt) 1 1 + τ e s �j ⟶ − α′! Γ j − α(t) μμ′! (t) 2 ( ) ( s0 ) ξμμ(s, t) t − mℰ [ 2 ] ( s0 ) B N N 0 A. N. Hiller Blin GHP2021 April 16th, 2021 3 Z+ photoproduction: 1+- • Focus on the 3 narrow states with large branching fractions into pion and vector Exotic minimum quark content: • QQ¯q1q¯2 • Pion exchange and VMD • Sizeable cross sections especially at low energies 102 J PAC 1 J PAC + Z c(3900) 10 Z (10610)+ b −1 + 10 Z b'(10650) [nb] [nb] Z n) Z n) −2 → 1 → 10 p p γ γ ( ( σ σ + 10−3 Z c(3900) −1 + 10 Z b(10610) + Z b'(10650) 10−4 5 10 15 20 20 30 40 50 60 70 W [GeV] https://github.com/dwinney/jpacPhoto W [GeV] γ p Albaladejo et al., 2008.01001 [hep-ph] γ p A. N. Hiller Blin GHP2021 April 16th, 2021 4 X and axial vector photoproduction • Focus on the famous X(3872), largely isospin violating, and similar non-exotic �c1 • � and � exchanges give main contributions • Extremely suppressed cross sections at high energies: threshold most promising 1 J PAC J PAC 102 −1 10 χ (1P) c1 X (3872) 10 [nb] [nb] 10−2 X p) X p) 1 → → −3 p p 10 γ γ ( ( σ 10−1 σ χ (1P) c1 10−4 X (3872) 10−2 10−5 4.5 5 5.5 6 6.5 7 20 30 40 50 60 W γ p [GeV] W γ p [GeV] A. N. Hiller Blin GHP2021 April 16th, 2021 5 Y (hybrid?) and vector-meson photoproduction • Known to be well described by Pomeron exchange: we use fits from our previous works to LE (GlueX/SLAC) and HE (HERA/ZEUS); parameters assumed intrinsic to Pomeron ANHB et al., Phys. Rev. D 94 (2016) 034002 Winney et al., Phys. Rev. D 100 (2019) 034019 • Coupling ratio to usual J/� estimated from decay ratios into gg�: R ’ ≈ 0.55 (compatible with HERA/ZEUS ) � σψ′!/σψ ∼ 0.39 RY ≈ 1.5 (suggests affinity to gluons as expected for a hybrid Y) • Good candidates for EIC: diffractive production increases with energy! 20 200 PAC PAC J / ψ J J / ψ J ψ(2S) ψ(2S) 15 Y (4260) 150 Y (4260) [nb] [nb] Y p) 10 Y p) 100 → → p p γ γ ( ( σ σ 5 50 0 0 4 6 8 10 40 60 80 100 W γp [GeV] W γp [GeV] A. N. Hiller Blin GHP2021 April 16th, 2021 6 LHCb discovery • 2015: exotic-like structures in J/ψ p channel found LHCb collaboration, PRL 115 (2015) 072001; PRL 122 (2019) 222001 c b J/ψ c¯ Λ s − b u u¯ K d u u p d Pc ≡ cc¯uud • K−p resonances (Λ: sud content) not sufficient to fit data Compact 5-quark state or weakly-bound (*) • D¯*Σc interpretations possible • Or possibly just kinematic effects A. N. Hiller Blin GHP2021 April 16th, 2021 7 Pentaquarks in J / ψ photoproduction • Confirmation of resonant nature vs kinematic effects • Peak close to threshold: low background • Non-resonant contribution — Pomeron exchange; Resonant amplitude — Breit-Wigner ansatz and VMD assumption GlueX data γ γ J/ψ J/ψ IP 1 Pc(4450) ′ ′ (nb) ppppσ ANHB et al., Phys. Rev. D 94 (2016) 034002 Winney et al., Phys. Rev. D 100 (2019) 034019 10−1 8.5 9.0 9.5 10.0 10.5 11.0 11.5 E γ (GeV) • Fits to GlueX data (no peak evidence) allowed for Pc branching fractions of 1-5% • If photoproduction experiments fail in finding signals, the scenario of LHCb signals being kinematic effects in the final-state is favoured A. N. Hiller Blin GHP2021 April 16th, 2021 8 Discriminatory power of polarization observables • Polarization observables more sensitive to broader or overlapping signals • With sensitivity studies provided by JPAC, Hall A LoI submitted: measuring A(K)LL LoI12-18-001 (PAC 46) C. Fanelli, L. Pentchev, B. Wojtsekhowski 0.8 0.2 PAC KLL ALL J W = 4.45 GeV- - - {3/2-,3/2 ,3/2 } {3/2 ,5/2+,5/2+} 0.1 - - + {3/2-,3/2 ,5/2 -} 0.6 {3/2 ,5/2+,3/2 } Background 0 Σ 0.4 -0.1 Pc 3/2- Pc 3/2+ Pc 5/2+ Pc 5/2- bkg only -0.2 8.5 9 9.5 10 10.5 11 11.5 12 0.2 Preliminary Eγ [GeV] Winney et al., Phys. Rev. D 100 (2019) 034019 https://github.com/dwinney/jpacPhoto dσ( ↑ ↑ ) − dσ( ↑ ↓ ) dσ⊥ − dσ∥ 0 0 20 40 60 80 A(K)LL = Σ = dσ( ↑ ↑ ) + dσ( ↑ ↓ ) dσ⊥ + dσ∥ θ • Beam asymmetries Σ can provide complementary information! A. N. Hiller Blin GHP2021 April 16th, 2021 9 Summary • X and Z states most promising close to threshold; diffractive states such as the Y are good candidates for the EIC • Pc searches require higher luminosity at low energies: polarization observables! Outlook: Albaladejo et al., SNOWMASS21-RF7_RF0-120 Albaladejo et al., SNOWMASS21-RF7_RF0-090 Albaladejo et al., SNOWMASS21-RF7_RF0-081 • Semi-inclusive reactions: though complicating the identification of final states, they have larger cross sections • Electroproduction: better experimental feasibility • Studies trivially extended to other XYZP once information about them is available A. N. Hiller Blin GHP2021 April 16th, 2021 10.
Load more

Recommended publications
  • 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]
  • 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]
  • Exotic Hadronic States
    Exotic Hadronic States Jeff Wheeler May 1, 2018 Abstract Background: The current model of particle physics predicts all hadronic ​ matter in nature to exist in one of two families: baryons or mesons. However, the laws do not forbid larger collections of quarks from existing. Tetraquark and ​ pentaquark particles have long been postulated. Purpose: Advance the particle ​ ​ landscape into a regime including more complex systems of quarks. Studying these systems could help physicists gain greater insight into the nature of the strong force. Methods: Many different particle colliders and detectors of varying ​ ​ energies and sensitivities were used to search for evidence of four- or five-quark states. Results: After a few false alarms, evidence for the existence of both ​ ​ tetraquark and pentaquark was obtained from multiple experiments. Conclusion: ​ Positive results from around the world have shown exotic hadronic states of matter to exist, and extended research will continue to test the leading theories of today and help further our understanding of the laws of physics. I. Introduction Since the discovery of atomic particles, scientists have attempted to determine their individual properties and produce a systematic method of grouping based on those properties. In the early days of particle physics, little was known besides the mere existence of protons and neutrons. With the advent of particle colliders and detectors, however, the collection of known particles grew rapidly. It wasn’t until 1961 that a successful classification system was produced independently by American physicist Murray Gell-Mann and Israeli physicist Yuval Ne’eman. This method was built upon the symmetric representation group SU(3).
    [Show full text]
  • LINE SHAPES of the EXOTIC C¯C MESONS X(3872)
    LINE SHAPES OF THE EXOTIC cc¯ MESONS X(3872) AND Z±(4430) DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Meng Lu, B.S., M.S. ***** The Ohio State University 2008 Dissertation Committee: Approved by Eric Braaten, Adviser Richard J. Furnstahl Adviser Klaus Honscheid Graduate Program in Junko Shigemitsu Physics c Copyright by Meng Lu 2008 ABSTRACT The B-factory experiments have recently discovered a series of new cc¯ mesons, including the X(3872) and the first manifestly exotic meson Z±(4430). The prox- 0 0 imity of the mass of the X to the D∗ D¯ threshold has motivated its identification as a loosely-bound hadronic molecule whose constituents are a superposition of the 0 0 0 0 charm mesons pairs D∗ D¯ and D D¯ ∗ . Factorization formulas for its line shapes are derived by taking advantage of the universality of S-wave resonances near a 2-particle threshold and by including the effects from the nonzero width of D∗ meson and the inelastic scattering channels of the charm mesons. The best fit to the line shapes of + 0 0 0 X in the J/ψπ π− and D D¯ π channels measured by the Belle Collaboration corre- 0 0 sponds to the X being a bound state whose mass is just below the D∗ D¯ threshold. The differences between the line shapes of X produced in B+ decays and B0 decays as + + 0 0 0 0 well as in decay channels J/ψπ π−,J/ψπ π−π , and D D¯ π are further derived by taking into account the effects from the closeby channel composed of charged charm mesons.
    [Show full text]
  • Multiquark Hadrons - Current Status and Issues
    Multiquark Hadrons - Current Status and Issues Ahmed Ali ∗ Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany ∗E-mail: [email protected] DOI: http://dx.doi.org/10.3204/DESY-PROC-2016-04/Ali Multiquark states having four and five valence quarks, called tetraquarks and pentaquarks, respectively, are now firmly established experimentally, with the number of such indepen- dent states increasing steadily over the years. They represent a new facet of QCD, but the underlying dynamics is currently poorly understood. I review some selected aspects of data and discuss several competing phenomenological models put forward to accommodate them. 1 Introduction Ever since the discovery of the state X(3872) by Belle in 2003 [1], a large number of multi- quark states has been discovered in particle physics experiments, conducted at the electron- positron and hadron colliders. They are exotic, having J PC quantum numbers not allowed for qq¯ states, or have too small a decay width for their mass, and, in some cases, their de- cay distributions have unfamiliar features not seen before. Most of them are quarkonium-like states, in that they have a (cc¯) or a (b¯b) component in their Fock space. A good fraction of them are electrically neutral but some are singly-charged. Examples are X(3872)(J PC = 1++), PC P + P + Y (4260)(J = 1−−), Zc(3900)±(J = 1 ), Pc(4450)±(J = 5/2 ), in the hidden charm P + P + sector, and Zb(10610)±(J = 1 ) and Zb(10650)±(J = 1 ), in the hidden bottom sector. P + The numbers in the parentheses are their masses in MeV.
    [Show full text]
  • Group Theoretic Classification of Pentaquarks and Numerical Predictions of Their Masses
    DEGREE PROJECT IN TECHNOLOGY, FIRST CYCLE, 15 CREDITS STOCKHOLM, SWEDEN 2019 Group Theoretic Classification of Pentaquarks and Numerical Predictions of Their Masses PONTUS HOLMA KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES EXAMENSARBETE INOM TEKNIK, GRUNDNIVÅ, 15 HP STOCKHOLM, SVERIGE 2019 Gruppteoretisk klassificering av pentakvarkar och numeriska förutsägelser av deras massor PONTUS HOLMA KTH SKOLAN FÖR ARKITEKTUR OCH SAMHÄLLSBYGGNAD Abstract In this report we investigate the exotic hadrons known as pentaquarks. A brief overview of relevant concepts and theory is initially presented in order to aid the reader. There- after, the history of this field with regards to theory and experiments is discussed. In particular, a group theoretic classification of these states is studied. A simple mass for- mula for pentaquark states is examined and predictions are subsequently made about the composition and mass of possible pentaquark states. Furthermore, this mass formula is modified to examine and predict additional pentaquark states. A number of numerical fits concerning the masses of pentaquarks are performd and studied. Future research is explored with regards to the information presented in this thesis. Sammanfattning I denna uppsats unders¨oker vi de exotiska hadronerna k¨andasom pentakvarkar. En kort ¨overblick av relevanta koncept och teorier ¨arpresenterade med syfte att underl¨atta f¨orl¨asaren. Historia i detta omr˚ademed avseende p˚ab˚adeteori och experiment ¨ar presenterad. Specifikt ing˚aren unders¨okningav gruppteoretisk klassificering av dessa tillst˚and.En enkel formel f¨ormassan hos pentakvarkar unders¨oksoch anv¨andsf¨oratt f¨orutsp˚amassorna och uppbyggnaden av m¨ojligapentakvarktillst˚and. Dessutom modi- fieras denna formel f¨oratt studera och f¨orutsp˚aytterligare pentakvarktillst˚and.Ett antal numeriska anpassningar relaterade till massorna hos pentakvarkarna genomf¨orsoch un- ders¨oks.Framtida forskning unders¨oksi koppling med material presenterat i uppsatsen.
    [Show full text]
  • Exotic Hadron Spectroscopy
    EPJ Web of Conferences 72, 00020 ( 2014) DOI: 10.1051/epjconf/20147200020 C Owned by the authors, published by EDP Sciences, 2014 Exotic Hadron Spectroscopy Alessandro Pilloni1,a 1Dipartimento di Fisica and INFN, “Sapienza” Università di Roma P.le Aldo Moro 2 - I-00185 Roma (Italy) Abstract. Since ten years ago experiments have been observing a host of exotic states decaying into heavy quarkonia. The interpretation of most of them still remains uncertain and, in some cases, controversial. Notwith- standing, a considerable progress has been made on the quality of the experimental information available and a number of ideas and models have been put forward to explain the observations. We will review the most promis- ing theoretical interpretations of exotic states, in particular we will discuss the nature of the charmonium-like resonances in the region 3850−4050 MeV, and propose a new mechanism to explain prompt X(3872) production cross section at hadron colliders. Finally, the phenomenology of doubly charmed states is commented. 1 Introduction • Tetraquarks: a quark pair (diquark) in the 3¯c (attrac- tive) configuration, neutralizing its color with an anti- Heavy quarkonium sector has proved to be extremely use- quark pair [6, 7]. A full nonet of states is predicted for ful for the understanding of QCD. In the limit mQ →∞, each spin-parity, i.e. a large number of states are ex- the gauge field dynamics can be simplified in terms of ef- pected. There is no need for these states to be close to fective potential models [1], or in terms of effective the- any threshold.
    [Show full text]
  • Study of the Strong Decays of Φ(2170) and the Future Charm-Tau Factory
    PHYSICAL REVIEW D 99, 036014 (2019) Study of the strong decays of ϕð2170Þ and the future charm-tau factory † Hong-Wei Ke1,* and Xue-Qian Li2, 1School of Science, Tianjin University, Tianjin 300072, China 2School of Physics, Nankai University, Tianjin 300071, China (Received 30 October 2018; published 19 February 2019) The present data imply that ϕð2170Þ may not be an excited state of ϕ but is a four-quark state with sss¯ s¯ constituents. Furthermore, there are no two mesons of ss¯ available to form a molecule that fits the mass spectrum of ϕð2170Þ; thus, we suggest it should be an sss¯ s¯ tetraquark state. In this scenario, we estimate its decay rates through the fall-apart mechanism. Our theoretical estimates indicate that its main decay modes 0 should be ϕð2170Þ into ϕf0ð980Þ, h1η, h1η , K1ð1270ÞK, and K1ð1400ÞK. Under this hypothesis, the ϕð2170Þ → Ãð890Þ0 ¯ Ãð890Þ0 þ − 0 0 modes K K , K K , and KLKS should be relatively suppressed. Since the width of h1 is rather large, at present, it is hard to gain precise data on BRðϕð2170Þ → h1ηÞ and 0 BRðϕð2170Þ → h1η Þ, the measurements of which may be crucial for drawing a definite conclusion about the inner assignment of ϕð2170Þ. We place our expectations on the proposed charm-tau factory, which will have much larger luminosity and better capacities. DOI: 10.1103/PhysRevD.99.036014 I. INTRODUCTION cannot find two available mesons [1] with ss¯ constituents to form a molecular hadron of which the mass fits the mass Very recently, a meson ϕð2170Þ came into the view of spectrum of ϕð2170Þ.
    [Show full text]
  • Exotics: Heavy Pentaquarks and Tetraquarks Arxiv:1706.00610V2
    DESY 17-071 Exotics: Heavy Pentaquarks and Tetraquarks Ahmed Ali,1 Jens S¨orenLange,2 and Sheldon Stone3 1DESY Theory Group, Notkestrasse 85, D-22607 Hamburg, Germany 2Justus-Liebig-Universit¨atGiessen, II. Physikalisches Institut, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany 3Physics Department, 201 Physics Building, Syracuse University, Syracuse, NY 13244-1130, USA July 31, 2017 Abstract For many decades after the invention of the quark model in 1964 there was no evidence that hadrons are formed from anything other than the simplest pairings of quarks and antiquarks, mesons being formed of a quark-antiquark pair and baryons from three quarks. In the last decade, however, in an explosion of data from both e+e− and hadron colliders, there are many recently observed states that do not fit into this picture. These new particles are called generically \ex- otics". They can be either mesons or baryons. Remarkably, they all decay into at least one meson formed of either a cc or bb pair. In this review, after the introduction, we explore each of these new discoveries in detail first from an experimental point of view, then subsequently give a theo- retical discussion. These exotics can be explained if the new mesons contain two-quarks and two- antiquarks (tetraquarks), while the baryons contain four-quarks plus an antiquark (pentaquarks). The theoretical explanations for these states take three divergent tracks: tightly bound objects, just as in the case of normal hadrons, but with more constituents, or loosely bound \molecules" similar to the deuteron, but formed from two mesons, or a meson or baryon, or more wistfully, they are not multiquark states but appear due to kinematic effects caused by different rescatterings of virtual particles; most of these models have all been post-dictions.
    [Show full text]
  • The Future of Heavy Flavor and Exotic Hadron Production in RHIC and LHC
    The Future of Heavy Flavor and Exotic Hadron Production in RHIC and LHC Xiaojun Yao MIT Snowmass Energy Frontier Preparatory Joint Topical Group Sessions July 8, 2020 Quarkonium Production: Factorization J/ψ Factorization in proton proton collision c c¯ p+p H+X i+j (QQ¯) +X σ ! = f f σ ! n i ⌦ j ⌦ hOni proton PDF short-distance production long-distance matrix element: of heavy quark pair evolution of pair into quarkonium universal QGP effects: dissociation, Heavy ion nuclear PDF (re)combination, energy loss etc In heavy ion, try to understand modifications from nuclear mediums Test universality of LDME in high multi p-p X.Dong July 1 9:50 am !2 Recent Theoretical Insights from Open System In vacuum, quarkonium described by Schrödinger equation @ 2 i (r)= r + V (r) (r) @t − M h i 1.0 Start with 1S, closed system 1S probability is conserved 0.8 0.6 1S wavefunction (t = 0) = 1S | i | i 0.4 1S (t) 2 =1 |h | i| 0.2 0.0 0.0 0.5 1.0 1.5 2.0 r !3 Recent Theoretical Insights from Open System In QGP, quarkonium described by stochastic Schrödinger equation @ 2 i (r)= r + V (r) (r) + iγ(r)+⇠(r, t) (r) @t − M − h i h i 1.0 Start with 1S, open system 1S probability NOT conserved 0.8 Stochastic forces —> wavefunction decoherence (t = 0) = 1S 0.6 | i | i 1S (t) 2 < 1 0.4 |h | i| 0.2 Dissociation of 1S 2 0.0 2S (t) > 0 if 2S exists 0.0 0.5 1.0 1.5 2.0 |h | i| r Recombination of 2S ! Correlated/uncorrelated recombination: from correlated pair from same/differential initial hard vertices !4 Upsilon in 5020 GeV PbPb Collision with cross-talk (correlated) recombination
    [Show full text]
  • Exotic Hadron States at Lhcb Daria Savrina (ITEP & SINP MSU) on Behalf of the Lhcb Collaboration
    Gatchina, Russia, August 6 – 10, 2018 Hadron Structure and QCD Exotic hadron states at LHCb Daria Savrina (ITEP & SINP MSU) on behalf of the LHCb collaboration Outline Why exotic hadrons? Exotic mesons study of the B+ → J/ψφK+ decay search for beautyfull tetraquarks Exotic baryons 0 - search in Λb → J/ψpπ steps towards future studies search for b-flavoured pentaquarks 2/30 Exotic hadrons Exotic hadrons – everything beyond qq-meson and qqq-baryon scheme Could be various multiquark states, hadron molecules, glueballs, hybrids... First predicted in 1964 the original papers by M.Gell-Mann and G.Zweig [CERN-TH-412, Phys.Lett. 8 (1964) 214] First seen by Belle in 2003 [Phys. Rev. Lett. 91, 262001 (2003)] B+ → X(3872)K+ X(3872) → J/ψπ+π- Expected quark content [ccuu] Internal structure is still under discussion 3/30 Exotic zoo „Charmonium-like“ states Not a very strict naming scheme X – neutral, first seen in B-mesons decays, positive parity Y – neutral, first seen in ee annihilation with initial state radiation, negative parity Z – charged (and their isospin partners) P – pentaquarks No clear pattern seen yet [S.Olsen,T.Skwarnicki, D.Zieminska, arXiv:1708.04012] Lots of predictions within different theoretical models Meson Hadro- Quarkonium Tightly bound Diquark-onium tetraquarks molecules quarkonium adjoint meson q q q q q q q q q q q q q q q q q q q q Would like not only to find new exotic hadrons, but also determine their quantum numbers 4/30 Searches for exotics Most of them are not narrow Need amplitude analysis Use Argand diagram to prove their resonance nature Decay quite fast Pentaquark lifetime ~10-23s Decays of b-hadrons Inclusive decays: good understanding of the initial state Relatively long lifetime Decays with charmonium provide a clear signature Direct production B Access to high mass region ~ 1 cm 5/30 The LHCb experiment [JINST 3 (2008) S08005] LHC: Cross-sections in the LHCb acceptance: σpp→bb = 72.0±0.3±6.8 µb @√s = 7TeV σpp→bb =144 ±1 ±21 µb @√s =13TeV [Phys.
    [Show full text]