DOCSLIB.ORG

Fully Heavy Tetraquark Bb¯C¯C: Lifetimes and Weak Decays

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Fully Heavy Tetraquark Bb¯C¯C: Lifetimes and Weak Decays Eur. Phys. J. C (2019) 79:645 https://doi.org/10.1140/epjc/s10052-019-7150-4 Regular Article - Theoretical Physics Fully heavy tetraquark bbc¯c¯: lifetimes and weak decays Gang Li1,a, Xiao-Feng Wang1,YeXing2,b 1 School of Physics and Engineering, Qufu Normal University, Qufu 273165, China 2 INPAC, SKLPPC, MOE Key Laboratory for Particle Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China Received: 30 April 2019 / Accepted: 18 July 2019 / Published online: 7 August 2019 © The Author(s) 2019 Abstract We study the lifetime and weak decays of the valuable. Fully-heavy four-quark state with no light quark + {bb} full-heavy S-wave 0 tetraquark T{¯cc¯} . Using the operator degrees of freedom is of this type and might be an ideal product expansion rooted in heavy quark expansion, we find probe to study the interplay between perturbative QCD and a rather short lifetime, at the order (0.1 − 0.3) × 10−12s non-perturbative QCD. depending on the inputs. With the flavor SU(3) symmetry, we Generally speaking, more heavy quarks correspond to a then construct the effective Hamiltonian at the hadron level, larger mass. For instance, there have been some phenomeno- and derive relations between decay widths of different chan- logical studies to determine the mass and the spectrum prop- nels. According to the electro-weak effective operators, we erties of the fully-heavy tetraquark bcb¯ c¯, including the con- classify different decay modes, and make a collection of the stituent quark and diquark model [38,39], simple quark {bb} → − 0 − golden channels, such as T{¯cc¯} B K Bc for the charm model [40], nonrelativistic effective field theory(NREFT) {bb} → − − [41], QCD sum rules [42,43], and quark potential model [44]. quark decay and T{¯cc¯} B D for the bottom quark decay. Our results for the lifetime and golden channels are helpful to In Ref. [41], the authors utilize the NREFT to determine the . search for the fully-heavy tetraquark in future experiments. mass with the upper bound as 12 58 GeV, consistent with the mass calculated in the simple quark model [40]. Despite of these studies, it is still not conclusive that whether the bcb¯ c¯ (or its charge conjugate cbc¯ b¯) is above or below the B B 1 Introduction c c threshold. It is likely that the bcb¯ c¯ lies below the threshold of the B B pair, which means that such a state is stable against In the past decades, quark model has achieved great suc- c c the strong interaction. In this case, the dominant decay modes cesses in the hadron spectroscopy study. In addition to would be induced by weak interaction. In a diquark-diquark the quark-anti-quark assignment for a meson and three- model [45], the S-wave fully-heavy tetraquark state bcb¯ c¯ can quark interpretation of a baryon, it allows the existence of form 0+ and 2+. In this paper we will mainly focus on the non-standard exotic states [1–6]. Since the observation of lowest lying state 0+, which might be assigned as a weakly- X(3872) in 2003 [1], many exotic candidates have been coupled state. announced on the experimental side in the heavy quarko- In this paper, we will first use the operator product expan- nium sector in various processes [7]. Charged heavy quarko- ± ± ± sion (OPE) technique and calculate the lifetime of the S-wave niumlike states Zc(3900) , Zc(4020) , Zb(10610) , and + ± 0 bcb¯ c¯. The light flavor SU(3) symmetry is a useful tools to Z (10650) observed by BES-III and Belle collaborations b analyze weak decays of a heavy quark, and has been success- [2–4] have already experimentally established as being fully applied to the meson or baryon system [46–61]. Though exotic, since they contain at least two quarks and two anti- the SU(3) breaking effects in charm quark transition might be quarks with the hidden QQ¯ . Until now, extensive theoretical sizable, the results from the flavor symmetry can describe the studies have been carried out to explore their internal struc- experimental data in a global viewpoint. To be more explicit, tures, production and decay behaviors [8–37]. Most of the one can write down the Hamiltonian at the hadron level with established states tend to contain a pair of heavy quark, and hadron fields and transition operators. Some limited amount thus the discovery of exotic states of new categories will be of input parameters will be introduced to describe the non- perturbative transitions. With the SU(3) amplitudes, one can a e-mail: [email protected] obtain relations between decay widths of different processes, b e-mail: [email protected] 123 645 Page 2 of 12 Eur. Phys. J. C (2019) 79 :645 ⎛ −− − − ⎞ which can be examined in experiment. Such an analysis is √1 √1 ⎜ c 2 c 2 c ⎟ also helpful to identify the decay modes that will be mostly ⎜ 1 − 0 1 0 ⎟ (F ¯ ){ } = ⎜ √ √ ⎟ useful to discover the fully-heavy tetraquark state. Since the c6 ij ⎝ 2 c c 2 c ⎠ − SU(3) analysis is based on the light quark flavor symmetry, √1 √1 0 0 2 c 2 c c thus the analytical results can work well in all states with ⎛ ⎞ ¯ ¯ 0 0 the same bcbc flavor constituents but with different quantum 0 b b [ ] ⎜ − ⎟ numbers, even for those molecular states Bc Bcs. Generally, ( ) ij = ⎝ −0 ⎠ , Fb3¯ b 0 b the molecular states may decay against the strong interaction −0 −− b b 0 than the weak interaction. ⎛ ⎞ The rest of this paper is organized as follows. In Sect. 2, + √1 0 √1 0 ⎜ b 2 b 2 b ⎟ we give the particle multiplets under the SU(3) symmetry. { } − − (F ) ij = ⎜ √1 0 √1 ⎟ . (2) Section 3 is devoted to calculate the lifetime of the tetraquark b6 ⎝ 2 b b 2 b ⎠ − − state using the OPE. In Sect. 4, we discuss the weak decays √1 0 √1 2 b 2 b b of many-body final states, including mesonic two-body or three-body decays and baryonic two-body decays. In Sect. In the meson sector, singly heavy mesons form an SU(3) 5, we present a collection of the golden channels. Finally, we triplet or anti-triplet, while the light mesons form an octet provide a short summary. plus a flavor singlet. These multiplets can be written as ⎛ ⎞ π0 η + + ⎛ ⎞ √ + √ π K B− ⎜ 2 6 ⎟ 0 ⎜ 0 ⎟ = ⎜ π − − √π + √η 0 ⎟ , T = ⎝ ⎠ , 2 Particle multiplets in SU(3) M8 ⎝ K ⎠ Bi B 2 6 0 − ¯ 0 √η K K −2 Bs ⎛ ⎞ ⎛ ⎞ 6 The tetraquark with the quark constituents bcb¯ c¯ does not 0 D0 D contain any light quark and thus is an SU(3) singlet. Recalling T = ⎝ + ⎠ , i = ⎝ − ⎠ . Di D D D (3) that diquark [QQ] or [qq] live in Acolor ⊗ Sflavor ⊗ Sspin + D D− spaces, with A and S representing the symmetry and anti- s s symmetry representation respectively, we find the allowed The weight diagrams of the multiplets are given in Figs. 1 ⊗ = ⊕ spin quantum numbers are 1 1 0 2. In this paper, we and 2. will mainly focus on the lowest lying state with J P = 0+, {bb} which is abbreviated as T{¯cc¯} . In the baryon sector, we give the SU(3) representations 3 Lifetime for baryons with different charm quantum numbers (C)or bottom quantum numbers (B) as follows. The triply heavy {bb} In this section we will discuss the lifetime of T{¯cc¯} using the baryon with C =−3 denoted as Fccc can form an SU(3) sin- −− {bb} → =− OPE [63,64]. The decay width of T{¯cc¯} X are as follows: glet ccc . Baryons with doubly heavy quarks(i.e. C 2, , = = B C 1, B 2) are supposed to be an anti-triplet(triplet) 3−→ { } 1 d p given as (T bb → X) = i (2π)4δ4 {¯c1¯c} 2m (2π)32E ⎛ ⎞ T X i i −− ⎛ + ⎞ (¯ ¯ ¯) ( ) { } cc ccu bc bcu ( − ) | |H| bb |2, ⎜ ⎟ ⎜ ⎟ pT pi X T{¯cc¯} (4) ( T ) = ⎜ − (¯ ¯ ¯) ⎟ , i = ⎝ 0 ( ) ⎠ , Fcc i ⎝ cc ccd ⎠ Fbc bc bcd i λ − (¯ ¯¯) 0 (bcs) μ cc ccs bc λ ⎛ ⎞ where mT , pT , and are the mass, four-momentum and spin 0 (bbu) {bb} bb of T{¯cc¯} , respectively. The electro-weak effective Hamilto- ⎜ ⎟ w i = ⎝ − ( ) ⎠ . nian He is given as Fbb bb bbd (1) ef f − ( ) ⎡ ⎤ bb bbs G Hew = √F ⎣ q ( q + q ) − ⎦ Consistently, the singly heavy baryons with C =−1(B = ef f Vc C1 O1 C2 O2 Vp C j O j 2 = , 1) are expected to form a triplet(anti-triplet) and a anti- q u c j=3 sextet(sextet) as [62] (5) ⎛ − − ⎞ 0 here, Ci and Oi are Wilson coefficients and operators. V sare ⎜ c c ⎟ ⎜ − 0 ⎟ the combinations of Cabibbo–Kobayashi–Maskawa(CKM) (F )[ ] = − , c3 ij ⎝ c 0 c ⎠ elements. Using the optical theorem, the total decay width of { } −− −0 ( bb → ) c c 0 T{¯cc¯} X can be rewritten as 123 Eur. Phys. J. C (2019) 79 :645 Page 3 of 12 645 (a) (b) (c) (d) Fig. 1 The weight diagrams for the anti-charmed meson triplet, charmed meson anti-triplet, bottom meson triplet and light meson octet (a) (b) (c) (d) (e) (f) (g) Fig. 2 The weight diagrams for the doubly heavy baryon are given in a–c, which anti-triplet Fcc to be (a), triplet Fbc to be (b), or triplet Fbb to be , , (c). The singly anti-charm baryon multiplets are Fc3 Fc6¯ shown in d, e, and the singly bottom baryon multiplets are given in f, g signed as Fb3¯ Fb6 { } 1 { } { } ( bb → ) = bb |T | bb with G F being the Fermi constant and VCKM being the T{¯cc¯} X T{¯cc¯} T{¯cc¯} (6) 2mT CKM mixing matrix.
Load more

Recommended publications
  • A Generalization of the One-Dimensional Boson-Fermion Duality Through the Path-Integral Formalsim
    A Generalization of the One-Dimensional Boson-Fermion Duality Through the Path-Integral Formalism Satoshi Ohya Institute of Quantum Science, Nihon University, Kanda-Surugadai 1-8-14, Chiyoda, Tokyo 101-8308, Japan [email protected] (Dated: May 11, 2021) Abstract We study boson-fermion dualities in one-dimensional many-body problems of identical parti- cles interacting only through two-body contacts. By using the path-integral formalism as well as the configuration-space approach to indistinguishable particles, we find a generalization of the boson-fermion duality between the Lieb-Liniger model and the Cheon-Shigehara model. We present an explicit construction of n-boson and n-fermion models which are dual to each other and characterized by n−1 distinct (coordinate-dependent) coupling constants. These models enjoy the spectral equivalence, the boson-fermion mapping, and the strong-weak duality. We also discuss a scale-invariant generalization of the boson-fermion duality. arXiv:2105.04288v1 [quant-ph] 10 May 2021 1 1 Introduction Inhisseminalpaper[1] in 1960, Girardeau proved the one-to-one correspondence—the duality—between one-dimensional spinless bosons and fermions with hard-core interparticle interactions. By using this duality, he presented a celebrated example of the spectral equivalence between impenetrable bosons and free fermions. Since then, the one-dimensional boson-fermion duality has been a testing ground for studying strongly-interacting many-body problems, especially in the field of integrable models. So far there have been proposed several generalizations of the Girardeau’s finding, the most promi- nent of which was given by Cheon and Shigehara in 1998 [2]: they discovered the fermionic dual of the Lieb-Liniger model [3] by using the generalized pointlike interactions.
    [Show full text]
  • 1 Standard Model: Successes and Problems
    Searching for new particles at the Large Hadron Collider James Hirschauer (Fermi National Accelerator Laboratory) Sambamurti Memorial Lecture : August 7, 2017 Our current theory of the most fundamental laws of physics, known as the standard model (SM), works very well to explain many aspects of nature. Most recently, the Higgs boson, predicted to exist in the late 1960s, was discovered by the CMS and ATLAS collaborations at the Large Hadron Collider at CERN in 2012 [1] marking the first observation of the full spectrum of predicted SM particles. Despite the great success of this theory, there are several aspects of nature for which the SM description is completely lacking or unsatisfactory, including the identity of the astronomically observed dark matter and the mass of newly discovered Higgs boson. These and other apparent limitations of the SM motivate the search for new phenomena beyond the SM either directly at the LHC or indirectly with lower energy, high precision experiments. In these proceedings, the successes and some of the shortcomings of the SM are described, followed by a description of the methods and status of the search for new phenomena at the LHC, with some focus on supersymmetry (SUSY) [2], a specific theory of physics beyond the standard model (BSM). 1 Standard model: successes and problems The standard model of particle physics describes the interactions of fundamental matter particles (quarks and leptons) via the fundamental forces (mediated by the force carrying particles: the photon, gluon, and weak bosons). The Higgs boson, also a fundamental SM particle, plays a central role in the mechanism that determines the masses of the photon and weak bosons, as well as the rest of the standard model particles.
    [Show full text]
  • A Young Physicist's Guide to the Higgs Boson
    A Young Physicist’s Guide to the Higgs Boson Tel Aviv University Future Scientists – CERN Tour Presented by Stephen Sekula Associate Professor of Experimental Particle Physics SMU, Dallas, TX Programme ● You have a problem in your theory: (why do you need the Higgs Particle?) ● How to Make a Higgs Particle (One-at-a-Time) ● How to See a Higgs Particle (Without fooling yourself too much) ● A View from the Shadows: What are the New Questions? (An Epilogue) Stephen J. Sekula - SMU 2/44 You Have a Problem in Your Theory Credit for the ideas/example in this section goes to Prof. Daniel Stolarski (Carleton University) The Usual Explanation Usual Statement: “You need the Higgs Particle to explain mass.” 2 F=ma F=G m1 m2 /r Most of the mass of matter lies in the nucleus of the atom, and most of the mass of the nucleus arises from “binding energy” - the strength of the force that holds particles together to form nuclei imparts mass-energy to the nucleus (ala E = mc2). Corrected Statement: “You need the Higgs Particle to explain fundamental mass.” (e.g. the electron’s mass) E2=m2 c4+ p2 c2→( p=0)→ E=mc2 Stephen J. Sekula - SMU 4/44 Yes, the Higgs is important for mass, but let’s try this... ● No doubt, the Higgs particle plays a role in fundamental mass (I will come back to this point) ● But, as students who’ve been exposed to introductory physics (mechanics, electricity and magnetism) and some modern physics topics (quantum mechanics and special relativity) you are more familiar with..
    [Show full text]
  • Glueball Searches Using Electron-Positron Annihilations with BESIII
    FAIRNESS2019 IOP Publishing Journal of Physics: Conference Series 1667 (2020) 012019 doi:10.1088/1742-6596/1667/1/012019 Glueball searches using electron-positron annihilations with BESIII R Kappert and J G Messchendorp, for the BESIII collaboration KVI-CART, University of Groningen, Groningen, The Netherlands E-mail: [email protected] Abstract. Using a BESIII-data sample of 1:31 × 109 J= events collected in 2009 and 2012, the glueball-sensitive decay J= ! γpp¯ is analyzed. In the past, an exciting near-threshold enhancement X(pp¯) showed up. Furthermore, the poorly-understood properties of the ηc resonance, its radiative production, and many other interesting dynamics can be studied via this decay. The high statistics provided by BESIII enables to perform a partial-wave analysis (PWA) of the reaction channel. With a PWA, the spin-parity of the possible intermediate glueball state can be determined unambiguously and more information can be gained about the dynamics of other resonances, such as the ηc. The main background contributions are from final-state radiation and from the J= ! π0(γγ)pp¯ channel. In a follow-up study, we will investigate the possibilities to further suppress the background and to use data-driven methods to control them. 1. Introduction The discovery of the Higgs boson has been a breakthrough in the understanding of the origin of mass. However, this boson only explains 1% of the total mass of baryons. The remaining 99% originates, according to quantum chromodynamics (QCD), from the self-interaction of the gluons. The nature of gluons gives rise to the formation of exotic hadronic matter.
    [Show full text]
  • Lectures on BSM and Dark Matter Theory (2Nd Class)
    Lectures on BSM and Dark Matter theory (2nd class) Stefania Gori UC Santa Cruz 15th annual Fermilab - CERN Hadron Collider Physics Summer School August 10-21, 2020 Twin Higgs models & the hierarchy problem SMA x SMB x Z2 Global symmetry of the scalar potential (e.g. SU(4)) The SM Higgs is a (massless) Nambu-Goldstone boson ~SM Higgs doublet Twin Higgs doublet S.Gori 23 Twin Higgs models & the hierarchy problem SMA x SMB x Z2 Global symmetry of the scalar potential (e.g. SU(4)) The SM Higgs is a (massless) Nambu-Goldstone boson ~SM Higgs doublet Twin Higgs doublet Loop corrections to the Higgs mass: HA HA HB HB yA yA yB yB top twin-top Loop corrections to mass are SU(4) symmetric no quadratically divergent corrections! S.Gori 23 Twin Higgs models & the hierarchy problem SMA x SMB x Z2 Global symmetry of the scalar potential (e.g. SU(4)) The SM Higgs is a (massless) Nambu-Goldstone boson ~SM Higgs doublet Twin Higgs doublet Loop corrections to the Higgs mass: HA HA HB HB SU(4) and Z2 are (softly) broken: yA yA yB yB top twin-top Loop corrections to mass are SU(4) symmetric no quadratically divergent corrections! S.Gori 23 Phenomenology of the twin Higgs A typical spectrum: Htwin Twin tops Twin W, Z SM Higgs Twin bottoms Twin taus Glueballs S.Gori 24 Phenomenology of the twin Higgs 1. Production of the twin Higgs The twin Higgs will mix with the 125 GeV Higgs with a mixing angle ~ v2 / f2 Because of this mixing, it can be produced as a SM Higgs boson (reduced rates!) A typical spectrum: Htwin Twin tops Twin W, Z SM Higgs Twin bottoms Twin taus Glueballs S.Gori 24 Phenomenology of the twin Higgs 1.
    [Show full text]
  • Search for a Higgs Boson Decaying Into a Z and a Photon in Pp
    EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2013-037 2015/09/07 CMS-HIG-13-006 Search for a Higgs boson decayingp into a Z and a photon in pp collisions at s = 7 and 8 TeV The CMS Collaboration∗ Abstract A search for a Higgs boson decaying into a Z boson and a photon is described. The analysis is performed using proton-proton collision datasets recorded by the CMS de- tector at the LHC. Events were collected at center-of-mass energies of 7 TeV and 8 TeV, corresponding to integrated luminosities of 5.0 fb−1 and 19.6 fb−1, respectively. The selected events are required to have opposite-sign electron or muon pairs. No excess above standard model predictions has been found in the 120–160 GeV mass range and the first limits on the Higgs boson production cross section times the H ! Zg branch- ing fraction at the LHC have been derived. The observed limits are between about 4 and 25 times the standard model cross section times the branching fraction. The ob- served and expected limits for m``g at 125 GeV are within one order of magnitude of the standard model prediction. Models predicting the Higgs boson production cross section times the H ! Zg branching fraction to be larger than one order of magni- tude of the standard model prediction are excluded for most of the 125–157 GeV mass range. arXiv:1307.5515v3 [hep-ex] 4 Sep 2015 Published in Physics Letters B as doi:10.1016/j.physletb.2013.09.057.
    [Show full text]
  • P-Shell Hyperon Binding Energies
    fruin&£t& P-Shell Hyperon Binding Energies D. Koetsier and K. Amos School of Physics University of Melbourne Parkville, Victoria 3052 Australia A shell model for lambda hypernuclei has been used to determine the binding energy of the hyperon in nuclei throughout the p shell. Conventional (Cohen and Kurath) potential energies for nucleon-nucleon interactions were used with hyperon-nucieon interactions taken from Nijmegen one boson exchange poten­ tials. The hyperon binding energies calculated from these potentials compare well with measured values. Although many studies have been made of hypernuclear structure1, most have been concerned with only a small number of hypernuclei. We consider the mass variation of hyperon binding energies in single hyperon hypernuclei throughout the entire p shell. We do so with the assumption that the ground states of p shell hypernuclei art- described by Os shell hypeions coupled to complex nuclear cores; cores which have closed Os shells and partially filled Op shells. Hypernuclear wavefunctions can then be determined by the diagonalisation of an appropriate Hamiltonian using the basis formed by such coupled states. The Hamiltonian to be considered is described in terms of one and two body matrix elements. The one body matrix elements were those of Cohen and Kurath2 for nucle- ons but were taken from data for the hyperon. The Cohen and Kurath (8-16)2BME potential energies were used for the two nucleon matrix elements, while the two body hyperon-nucleon matrix elements were calculated from the Nijmegen one boson ex­ change potentials3. These hyperon-nucleon potentials include amplitudes associated with several different meson exchanges, but do not allow for medium effects due to the presence of the other particles, for the transfer of more than one boson, or for basis space truncation.
    [Show full text]
  • B Meson Decays Marina Artuso1, Elisabetta Barberio2 and Sheldon Stone*1
    Review Open Access B meson decays Marina Artuso1, Elisabetta Barberio2 and Sheldon Stone*1 Address: 1Department of Physics, Syracuse University, Syracuse, NY 13244, USA and 2School of Physics, University of Melbourne, Victoria 3010, Australia Email: Marina Artuso - [email protected]; Elisabetta Barberio - [email protected]; Sheldon Stone* - [email protected] * Corresponding author Published: 20 February 2009 Received: 20 February 2009 Accepted: 20 February 2009 PMC Physics A 2009, 3:3 doi:10.1186/1754-0410-3-3 This article is available from: http://www.physmathcentral.com/1754-0410/3/3 © 2009 Stone et al This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/ licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract We discuss the most important Physics thus far extracted from studies of B meson decays. Measurements of the four CP violating angles accessible in B decay are reviewed as well as direct CP violation. A detailed discussion of the measurements of the CKM elements Vcb and Vub from semileptonic decays is given, and the differences between resulting values using inclusive decays versus exclusive decays is discussed. Measurements of "rare" decays are also reviewed. We point out where CP violating and rare decays could lead to observations of physics beyond that of the Standard Model in future experiments. If such physics is found by directly observation of new particles, e.g. in LHC experiments, B decays can play a decisive role in interpreting the nature of these particles.
    [Show full text]
  • Arxiv:2106.01179V1 [Hep-Ph] 2 Jun 2021
    The bosonic algebraic approach applied to the [QQ][Q¯Q¯] tetraquarks A. J. Majarshin,1, ∗ Yan-An Luo,1, y Feng Pan,2, 3, z and J. Segovia4, x 1School of Physics, Nankai University, Tianjin 300071, P.R. China 2Department of Physics, Liaoning Normal University, Dalian 116029, P.R. China 3Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001, USA 4Dpto. Sistemas F´ısicos, Qu´ımicos y Naturales, Univ. Pablo de Olavide, 41013 Sevilla, Spain (Dated: June 3, 2021) ¯¯ ¯ The exact eigenenergies of the T4c = [cc][¯cc¯], T4b = [bb][bb], and T2[bc] = [bc][bc¯] tetraquarks are calculated within the extended transitional Hamiltonian approach, in which the so-called Bethe ansatz within an infinite-dimensional Lie algebra is used. We fit the parameters appearing in the transitional region from phenomenology associated with potential candidates of tetraquarks. The rotation and vibration transitional theory seems to provide a better description of heavy tetraquarks than other attempts within the same formalism. Our results indicate that the pairing strengths are large enough to provide binding; an extended comparison with the current literature is also performed. I. INTRODUCTION Fully-heavy tetraquarks have recently received consid- erable attention, both experimentally and theoretically. A system of interacting bosons is a well-studied prob- On the experimental side, it is thought that all-heavy lem. Having its roots in the Bose-Einstein conden- tetraquark states will be very easy to spot because their sates [1{3], the framework has been applied to studies masses should be far away from the typical mass regions of nuclear and molecular structure [4{6], and examples populated by both conventional heavy mesons and the of algebraic methods applied to hadron physics can be XYZ states discovered until now [32].
    [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]
  • Multi-Vector Boson Production Via Gluon-Gluon Fusion
    Multi-Vector Boson Production via Gluon-Gluon Fusion Pankaj Agrawal and Ambresh Shivaji Institute of Physics Sachivalaya Marg Bhubaneswar 751005, INDIA The data is being recorded at the Large Hadron Collider (LHC) for quite some- time. All this data has produced only strong support for the standard model (SM). There does not seem to be any significant evidence for beyond the standard model (BSM) scenarios [1]. Various extensions of the standard model are getting seriously constrained. There also appear to be strong suggestions that the only missing piece of the SM, the Higgs boson exists. However, SM is unsatisfactory in a number of ways. One has to keep looking for any hint for the new physics signal. It would appear that to test the model and look for the directions for the extension, one may need to probe as many SM processes as possible. In particular, one would be looking for the processes that have many particles in the final state or have small cross sections. At the LHC and proposed hadron colliders such as HE-LHC, one of the features is large gluon luminosity. Therefore, some of the gg scattering processes, which occur at the one-loop level and have many particles in the final state, would be important and observable at the LHC. They can also contribute to the backgrounds to the BSM physics scenarios. We are interested in a particular set of processes pp → V V ′g/γX. Here V, V ′ = W,Z,γ. We are particularly interested in the contribution from the gluon-gluon scattering. Since W,Z,γ do not couple to the gluons directly, these processes take place at the one-loop.
    [Show full text]
  • Classification of Elementary Particles
    CLASSIFICATION OF ELEMENTARY PARTICLES #Classification On the basis of “SPIN”: - •Elementary Particles are categorised in two classes i.e. Bosons and Fermions: - BOSONS Introduction: In particle physics boson is the type of particle that obeys the rule of Bose- Einstein statistics. These bosons have quantum spin having integral value 0, +1, -1, +2, -2, etc. •History: The name Boson comes from the surname of Indian physicist Satyendra Nath Bose and physicist Albert Einstein. They develop a method of analysis called Bose-Einstein Statistics. In an effort to understand the Plank's law, Bose proposed a method to analyse the behaviour of photon in 1924.He sent paper to Einstein. One of the most dramatic effect of Bose- Einstein Statistics is the prediction that boson can overlap and coexist with other bosons. Because of this it is possible to become a photon to laser. The name Boson First coined by scientists Paul Dirac in the honour of famous scientists Satyendra Nath Bose and Albert Einstein. Regarding: •Boson are fundamental particle such as gluons ,W ,Z boson, recently discovered Higgs boson aka God particle and Graviton. •Boson may be elementary like Photon or Composite i.e.made with two or more elementary particle. •All observed particles are either fermion or Boson. Types of Bosons- •Bosons are categorised into two categories; Gauge Boson: Gauge Boson are the particle that Carries the interaction of fundamental forces between particles. All known Gauge Boson have spin 1 and therefore all Gauge Boson are vector. •gauge boson is characterized into 5 categories. •Gluons(g): That carries strong nuclear forces between matter particle.
    [Show full text]