The majority of QCD states are unstable resonances that couple strongly to multi-particle states, with a significant fraction of these coupling to asymptotic three-particle states. Lattice QCD, being a framework that incorporates all dynamical coupling non-perturbatively, provides a promising pathway toward studying the excited states of the theory. Although challenging, lattice QCD...
Hadronic matrix elements of the QCD energy-momentum tensor can be parametrized in terms of gravitational form factors (GFFs) which, through their dependence on momentum transfer and decomposition into quark and glue contributions, encode information about the distributions of energy, angular momentum, pressure, and shear forces within a hadron spatially and amongst its constituents. GFFs can...
We present the first determination of the hadronic decays of the lightest exotic JPC=1-+ resonance in lattice QCD. Working with SU(3) flavor symmetry, where the up, down and strange-quark masses approximately match the physical strange-quark mass giving mπ∼700 MeV, we compute finite-volume spectra on six lattice volumes which constrain a scattering system featuring eight coupled channels....
I will discuss recent lattice calculations of Gegenbauer moments of twist-two light cone distribution amplitudes (LCDAs) of the RQCD collaboration. There has been a lot of progress, in particular regarding taking the continuum limit and the matching to the modified minumal subtraction scheme. LCDAs play an important role in the physics of exclusive processes.
We show that using renormalization-group summation to generate the QCD radiative corrections
to the $\pi-\gamma$ transition form factor, calculated within lightcone sum rules, leads the
strong coupling free of Landau singularities while preserving the QCD form-factor asymptotics.
This enables a reliable applicability of the LCSR method to momenta well below 1~GeV$^2$.
This way, one can use...
We suggest to probe the pion light-cone distribution amplitude, transforming the
dispersion relation for the pion electromagnetic form factor into
an equation between the spacelike form factor
$F_\pi(Q^2)$ and the integrated modulus of the timelike form factor.
For $F_\pi(Q^2)$, the QCD light-cone sum rule in terms of the
pion light-cone distribution amplitudes is used. From this...
The mathematical method of Padé approximants is put forward to reconstruct the Borel transformed series of the correlator triggering either the tau or the Higgs decay and extract higher-order corrections in a model-independent way. The use of the D-log Padé approximants provides valuable information to its analytic structure and yields, together with the standard Padé approximants, reliable...
An enhanced phenomenological model that includes isospin-symmetry breaking is presented in this letter. The model is then used in a number of statistical fits to the most recent experimental data for the radiative transitions $V\!P\gamma$ ($V=\rho$, $K^*$, $\omega$, $\phi$ and $P=\pi$, $K$, $\eta$, $\eta^{\prime}$) and estimations for the mixing angles amongst the three pseudoscalar states...
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to...
We investigate the single transverse-spin asymmetry with a $sin(2\phi-\phi_S)$ modulation in the pion-induced Drell-Yan process within the theoretical framework of the transverse momentum dependent (TMD) factorization. The asymmetry is contributed by the convolution of the Boer-Mulders function and the transversity. We adopt the model results for the distributions of the pion meson and the...
A complete theoretical analysis of the $C$-conserving semileptonic decays $\eta^{(\prime)}\to\pi^0l^+l^-$ and $\eta^\prime\to\eta l^+l^-$ ($l=e$ or $\mu$) is carried out within the framework of the Vector Meson Dominance (VMD) model. An existing phenomenological model is used to parametrise the VMD coupling constants and the associated numerical values are obtained from an optimisation fit to...
We have recently completed the coupled dispersive analysis of $\pi K$ pi pi -> K anti-K data.
We show that just fitting data fails to satisfy the dispersive representation and leads to inconsistencies with threshold sum-rules as well as unreliable resonance parameterizations.
Our main result is a set of constrained fits to data that satisfy 16 dispersion relations of different kinds and...
High statistics samples from modern experiments triggered an essential work on revisiting theoretical models and tools applied to analyze the resonance phenomena of QCD.
In this talk, I will discuss two exotic-resonance candidates, $a_1(1420)$ and $\pi_1(1600)$ cleared up over the last few years using data of the COMPASS experiment.
With our recent analysis [hep-ph:2006.05342], the...
Hadron spectroscopy is an important tool to study quark dynamics by various hadron properties such as resonance mass, spin, parity, angular momentum, etc. In addition to these, magnetic moments and various possible decay channels are of keen interest to know the intrinsic interaction. A potential model is used to determine these properties for a particular hadron, and the results are compared...
We study the hidden-charm pentaquark states $udsc\bar{c}$ with spins 1/2, 3/2, and 5/2 within the QCD sum-rule approach. We construct the currents for the particular configuration of the pentaquark states that consist of the flavor singlet three-quark cluster $uds$ of spins 1/2 and 3/2 and the two-quark cluster $\bar cc$ of spin 1, where both clusters are in a color-octet state. From the QCD...
rest at LEAR, the CERN-Munich multipoles for $\pi\pi$ elastic scattering, the $S$-wave from BNL data on $\pi\pi$ scattering into $K_SK_S$, and from GAMS data on $\pi\pi\to \pi^0\pi^0, \eta\eta$, and $\eta\eta'$. The analysis reveals the existence of ten scalar isoscalar resonances. The resonances can be grouped into two classes: resonances with a large SU(3) singlet component and those with
a...
New data from BESIII and LHCb indicate the existence of two hidden charm, open strangeness resonances, dubbed Zcs(3985) and Zcs(4003). Their quasi-degeneracy reproduces, in the strange quark sector, the situation observed with X(3872) and Zc(3900) in the u,d quark sector. The Zcs resonances neatly fit into two broken SU(3)f symmetry nonets with JP = 1+ and opposite charge-conjugation. The mass...
Results for the ground states and excited states of glueballs in Yang-Mills theory with $J^{\pm+}$, J=0,1,2,3,4, from Bethe-Salpeter equations are presented. The input comes from parameter-free Dyson-Schwinger calculations of the propagators and vertices. We compare with the corresponding lattice results and add some excited states to the known spectrum.
I summarize recent work pointing towards the existence of a universal holographic light-front wavefunction for light mesons and nucleons. This holographic wavefunction, which describes simultaneously a bound state in light-front QCD and the propagation of string modes in a dilaton-modified 5-dimensional anti de Sitter spacetime, is a specific realization of the gauge-gravity duality. The...
AMBER is a newly proposed fixed-target experiment at the M2 beam line of the SPS, devoted to various fundamental QCD measurements, with a Proposal very recently approved by the CERN Research Board for a Phase-1 program and a Letter of Intent made public for a longer term program.
Such an unrivalled installation would make the experimental hall EHN2 the site for a great variety of measurements...
Recently, jet measurements in DIS events close to Born kinematics have been proposed as a new probe to study transverse-momentum-dependent (TMD) PDFs, TMD fragmentation functions, and TMD evolution. We report measurements of lepton-jet momentum imbalance and hadron-in-jet correlations in high-$Q^2$ DIS events collected with the H1 detector at HERA. The jets are reconstructed with the kT...
I will briefly review the current status of transverse-momentum-dependent (TMD) factorization and related frameworks, focusing on its applicability at the LHC.
