The 0 glueball in pure gauge theory is a well defined quantity that can be used to test our understanding and ability to solve theory. It is also interesting to understand how, or if, the 0 glueball contributes to the physical light flavour singlet 0 mesons. Finding glueball degrees of freedom in the flavour singlet mesons is complicated, because other non-perturbative objects such as tetraquar...

The tetraquark assignement for light scalar states below 1 GeV is discussed on the light of strong decays. The next-to-leading order in the large-N expansion for the strong decays is considered. Mixing with quarkonia states above 1 GeV is investigated within a chiral approach and the inclusion of finite-width effects is taken into account. Talk given at the International School of Nuclear Physi...

We derive exact yet practical covariant equations of quantum field theory describing a tetraquark in terms mix four-quark states $2q2\overline{q}$, and two-quark $q\overline{q}$. A feature our approach is that it avoids the overcounting problems usually plague formulations few-body (the only exception being two-body Bethe-Salpeter equation). This achieved by coupling $2q2\overline{q}$ to $q\ove...

We study all-charm tetraquarks in the front form of Hamiltonian dynamics using many-body basis function approach known as light-front quantization. The model contains transverse and longitudinal confining potentials a one-gluon-exchange effective potential. calculate masses two-charm-two-anticharm states focusing on lowest state. also two-quark four-quark estimates meson-meson breakup threshold...

We discuss the production mechanism of a new state, putative fully charm tetraquark, observed recently by LHCb at M = 6.9 GeV in $J/\psi J/\psi$ channel. Both single parton scattering (SPS) and double (DPS) mechanisms are considered. calculate distribution invariant mass four-quark system $M_{4c}$ for SPS DPS $c c \bar c$ $k_t$-factorization approach with modern unintegrated gluon functions (UG...

Motivated by the recently observation of tetraquark Tcc+ state, in this work I revisit Heavy-Meson Effective Theory to perform a simplified field-theoretical study possible deuteron-like D(⁎)D(⁎),B¯(⁎)B¯(⁎) and D(⁎)B¯(⁎) molecules. In particular, using data from as input fix potential associated shallow-bound DD⁎ system with I(JP)=0(1+), conditions for formation other loosely-bound states doubl...

Inspired by the very recently discovered tetraquark states $T_{c\bar s 0}^a(2900)^{0,++}$ from LHCb Collaboration, we predict existence of a new charmed-strange pentaquark system, $c\bar nnn$, which is closely connected to n\bar n$ exchanging $\bar into $nn$ with $n=u,d$. Especially, it suggested experimentally search for predicted system via weak decays $B$ mesons or $b$-baryons, support study...

Frank E. Close Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Keble Road, Oxford, OX1 3NP, United Kingdom (Received 27 February 2008; published 8 May 2008) We propose a search for the newly discovered tetraquark candidate Zð4430Þ in photoproduction. Based on the Belle results, we show that if Zð4430Þ is a genuine resonance, its significantly large coupling to 0 will cause ...

Fragmentation functions of pion, kaon, and nucleon are determined by global analyses of hadronproduction data in ee annihilation. It is particularly important that uncertainties of the fragmentation functions are estimated for the first time. We found that light-quark and gluon fragmentation functions have large uncertainties, so that one should be careful in using these functions for hadron-pr...