Conveners
Hadronic and nuclear spectrum and interactions: LT1
- Christopher Thomas (University of Cambridge)
Hadronic and nuclear spectrum and interactions: LT1
- Gunnar Bali (University of Regensburg)
Hadronic and nuclear spectrum and interactions: LT1
- Jeremy Green (DESY)
Hadronic and nuclear spectrum and interactions: LT1
- Matthew Wingate (University of Cambridge)
Hadronic and nuclear spectrum and interactions: LT1
- Christine Davies (University of Glasgow)
Hadronic and nuclear spectrum and interactions: LT1
- Sara Collins (University of Regensburg)
Hadronic and nuclear spectrum and interactions: TR5
- Felix Erben (CERN)
Hadronic and nuclear spectrum and interactions: LT1
- Sinya Aoki (Yukawa Institute for Theoretical Physics, Kyoto University)
Hadronic and nuclear spectrum and interactions: LT1
- William Detmold (MIT)
Hadronic and nuclear spectrum and interactions: TR5
- Fernando Romero-Lopez (MIT / Uni Bern)
Hadronic and nuclear spectrum and interactions: LT1
- Colin Morningstar (Carnegie Mellon University)
Hadronic and nuclear spectrum and interactions: LT1
- David Wilson (University of Cambridge)
We collect spectra extracted in the $I=\ell=1$ $\pi\pi$ sector provided by various lattice QCD collaborations and study the $m_\pi$ dependence of $\rho$-meson properties using Hamiltonian Effective Field Theory (HEFT).In this unified analysis, the coupling constant and cutoff mass, characterizing the $\rho - \pi \pi$ vertex, are both found to be weakly dependent on $m_\pi$, while the mass of...
We present our study of the $\rho(770)$ and $K^*(892)$ resonances from lattice QCD employing domain-wall fermions at physical quark masses. We determine the finite-volume energy spectrum in various momentum frames and obtain phase-shift parameterizations via the Lรผscher formalism, and as a final step the complex resonance poles of the $\pi \pi$ and $K \pi$ elastic scattering amplitudes via an...
In this talk, we present a numerical exploration of the relativistic field theory (RFT) formalism for three pions with all possible values of non-maximal isospin, $I_{\pi\pi\pi} = 2$, $1$, and $0$. Using the published generic-isospin extension of the RFT formalism and applying our open-source Python library to implement the formalism, we predict an array of three-pion energies for realistic...
We generalize the three-particle finite-volume formalism to allow for multiple three-particle channels, focussing on the two-channel ฮทฯฯ and (positive G-parity sector of the) KKฯ system in isosymmetric QCD. The formalism we obtain is thus appropriate to study the b1(1235) and ฮท(1295) resonances. The derivation is made in the generic relativistic field theory approach using the time-ordered...
We study systems of two and three mesons composed of pions and kaons at maximal isospin using the E250 CLS ensemble with physical quark masses. Using the stochastic LapH method, we determine the energy spectrum of these systems including many levels in different momentum frames. Using the two- and three-body finite-volume formalism, we constrain the two and three-meson K matrix, including not...
The three-body problem, renowned for its unsolvable nature in celestial mechanics and homonymous science fiction, is not only solvable in the quantum realm regarding spectra but also offers profound insights into QCD. Many hadronic resonances, such as the Roper resonance, $T_{cc}$, and $\omega$, can be thoroughly understood only by studying the underlying three-body dynamics. As a step toward...
The existence of bound doubly heavy tetraquark states was confirmed by the recent LHCb discovery of the doubly charmed $T_{cc}$, less than 1MeV below the meson pair threshold. Other states with two heavy (bottom or charm) quarks could also be bound, perhaps more deeply. Here we discuss our previous work, and the improvements in our current, updated analysis of various heavy-heavy-light-light...
We report our ongoing study of the pole structure of doubly charmed
tetraquark $T_{cc}$. In this work we considered diquark-antidiquark,
molecular and scattering operators in our analysis. Relativistic Heavy
Quark action and clover improved Wilson action have been employed
for charm and light quarks respectively. We varied the light quark
mass to determine the region where three body...
I will present how the DD scattering amplitude and the pole positions in Tcc channel vary with the charm and the light-quark masses. This will be based on our lattice results for five charm quark masses and results by other groups for various light-quark mass. Effective Field Theory for DD interaction mediated by pions implies attraction at short range and a slight repulsion at long range...
The analysis of $DD^*$ scattering, where the exotic state $T_{cc}$ was discovered in 2021, in lattice QCD is complicated by long-range interactions, which make the extraction of the scattering amplitude via the Lรผscher method dubious. We tackle this problem with a multifaceted approach: first, in addition to the relevant scattering operators, we incorporate a diquark-antidiquark interpolator...
We present a strategy for applying the relativistic three-particle scattering formalism to reactions of non-degenerate mesons of arbitrary angular momenta. For concreteness, we focus on the $DD\pi$ system in the charm $C=2$ and isospin $I=0$ sectors, where the $T_{cc}^+$ tetraquark appears as a pole in the elastic $DD\pi \to DD\pi$ scattering amplitude. We solve integral equations for a model...
The discoveries of exotic hadrons with heavy quark degrees of freedom are stimulating theoretical studies to understand their physical mechanism, and lattice QCD calculations of relevant hadron-hadron interactions are expected to play a crucial role.
In this talk, we present lattice QCD studies of hadron interactions with charm quark degrees of freedom by the HAL QCD method. In particular, we...
We determine the energies and decay constants of the lowest-lying positive-parity bottom-strange and charm-strange mesons using lattice QCD. The calculations are performed with domain-wall up, down, and strange quarks and with an anisotropic clover action for the heavy quarks, on seven different RBC/UKQCD ensembles with pion masses ranging from a near physical $m_\pi\approx 139 MeV$ up to...
The spectrum of static-light and static-charm mesons is studied using optimized distillation in two different $N_f=3+1$ QCD ensembles with pion masses of $m_{\pi}\approx 800\,\text{MeV}$ and $m_{\pi}\approx 420\,\text{MeV}$. Local and derivative-based operators are used to access states of multiple quantum numbers. The use of optimal profiles is shown to improve the overlap with the energy...
The masses of the lowest charmonium states are determined on a large set of coordinated lattice simulations (CLS) gauge ensembles with $N_f=2+1$ sea quark flavours of non-perturbatively improved Wilson fermions. The inverse lattice spacing is varied from about 2 GeV up to more than 5 GeV, enabling a controlled continuum limit extrapolation. This allows the impact of the neglected charm quark...
We study the light meson - charmonium - glueball mixing using flavor-singlet meson operators built from optimal distillation profiles together with purely gluonic operators in different $J^{PC}$ channels at two different pion masses ($m_{\pi} \approx 420,\ 800$ MeV) in two $N_f = 3 + 1$ ensembles at almost physical charm quark mass. We observe non-zero mixing correlations between the different...
We present a calculation of exotic tetraquark states with two $\bar{b}$-quarks and of the lowest-energy $J^P=0^+$ and $1^+$ $B_s$-mesons using Lattice NRQCD. The calculations have been performed on the $N_f=2+1$ Wilson-Clover gauge-field configurations from the CLS consortium. For the $ud\bar{b}\bar{b}$ and $us\bar{b}\bar{b}$ tetraquarks we obtain bound states below the respective $BB^*$ and...
We report on our lattice QCD computation of the static-light $\bar Q \bar Q qq$ potentials, using the CLS configurations and the OpenQ*D codebase. We utilize a set of 24 creation operators, corresponding to 12 sectors characterized by isospin, angular momentum and parity quantum numbers for $uu$, $ud$ or $dd$ light quarks and 6 sectors for $us$ or $ds$ light quarks. We include off-axis...
We use existing antistatic-antistatic potentials computed with two flavors of twisted mass fermions to study antiheavy-antiheavy-light-light four-quark systems in the Born-Oppenheimer approximation. We do not only compute masses of bound states, but also search for poles in the scattering amplitude above the lowest meson-meson threshold, to detect resonances and determine their parameters. We...
QCDย permits the existence of hybrid mesons that are made up of both quarks and gluons, including exotic states, i.e., quantum numbers prohibited for pure quark-antiquark states, with possible candidates found in experiments. We present static hybrid potentials measured via Laplace trial states together with static-light meson thresholds on $N_f=3+1$ dynamical fermion ensembles with 420 MeV...
It is now clear that bound multiquark states are possible with heavy quarks. Several tetraquark and a handful of pentaquark states have been observed in experiments. However, most of these are molecular states just below threshold. Lattice QCD holds an advantage over experiment in studying possible states with more heavy quarks. Apart from measuring the mass, it is now interesting to...
Research into doubly heavy tetraquarks has become highly relevant, especially with the recent discovery of the doubly charmed tetraquark $T_{cc}$. In this study, we present a lattice investigation of S-wave $D\bar{B}^{(*)}$ scattering within the isoscalar axial-vector and scalar channels. Both the processes feature the flavor combination $bc\bar u\bar d$, which could potentially host $T_{bc}$...
The timelike pion form factor is a rare example of a form factor that can be measured on the lattice in the timelike region without analytic continuation from the spacelike region. The most precise experimental results disagree near the $\rho$ resonance, leading to diverging estimates of hadronic vacuum polarization. We will present a calculation of the timelike pion form factor using a...
Transition amplitudes to two-hadron states arise in the interactions between hadrons and electromagnetic and weak currents.
From these transitions, we can study internal charge distributions or rare weak decays of hadrons.
In this talk, we present the first calculation of a transition amplitude to a coupled-channel of two-meson states from first principles.
We extract the timelike form...
The finite-volume spectrum of 3-hadron systems on the lattice can be captured by the so-called K-matrix. This scheme-dependent object can be related to the corresponding 3-to-3 scattering amplitude in infinite volume, which can in turn be calculated using a low-energy effective field theory such as chiral perturbation theory (ChPT). We present the next-to-leading-order calculation of the...
We present results for the $N\pi$ finite-volume spectra on three different lattice volumes with fixed lattice spacing $a=0.116$ fm and $m_\pi$ ranging from $249$ MeV to $137$ MeV. The calculations employ $N_f=2+1$ doubly-HEX-smeared clover fermions. We perform the calculations with total momenta up to $\vec{P}=(1,1,1)\frac{2\pi}{L}$ and all relevant irreps. Using the L\"uscher method we fit...
The quantification of lattice artifacts in two-baryon variational bounds is an essential prerequisite for a controlled determination of multi-baryon scattering parameters. Recent work suggests the existence of large lattice artifacts in the SU(3) flavor singlet channel. This channel is phenomenologically interesting because the ground state is the hypothesized H-dibaryon. In this talk I...
$\Lambda_{c}-N$ central and tensor potentials in the spin singlet channel ($^1S_0$) and the spin triplet coupled channel ($^3S_1-{^3D_1}$) from lattice QCD by using HAL QCD method. We perform the first physical point simulation by employing gauge configurations generated by the HAL Collaboration at $m_{\pi}\simeq137$ MeV, $m_{K}\simeq 502$ MeV, and $a \simeq 0.0844$ fm on $96^4$ lattices...
The interaction between the nucleon and charmonia ($J/\psi$ and $\eta_c$) is expected to deepen our understanding of various aspects in nonperturbative QCD ranging from the origin of nucleon mass to $J/\psi$ suppression in heavy ion collisions and properties of hidden-charm pentaquark states. Here, we present the first lattice QCD studies on low-energy $NJ/\psi$ and $N\eta_c$ interactions...
We determined the proton-proton fusion matrix element and constrained the corresponding low energy constant L_{1,A} in the pionless EFT at a pion mass of 432 MeV. To control the systematics, we employed both bilocal and hexaquark interpolation operators. Given that the two-nucleon system at unphysical pion mass is likely to be a shallow bound state or scattering state, the finite volume...
We present lattice gauge theory results for $O(1/m)$ and $O(1/m^2)$ relativistic corrections to the static potential. These results are based on Wilson loops with two field strength insertions, which we renormalize using gradient flow. Moreover, we use tree-level improvement to reduce discretization errors in the Wilson loop at small temporal and spatial separation. We use computations for...
I will discuss scalar and tensor charmonium resonances determined using lattice QCD. Working at $m_\pi\approx 391$ MeV, more than 200 finite-volume energy levels are computed and these are used in extensions of the Lรผscher formalism to determine infinite volume scattering amplitudes. Working in the approximation where charm-annihilation is forbidden, the ground state $\chi_{c0}(1P)$ and...
We explore the decay properties of the isovector and isoscalar $1^{-+}$ light hybrids $\pi_1$ and $\eta_1$ $\pi_1$ in $N_f=2$ lattice QCD at a pion mass $m_\pi\approx 417~\mathrm{MeV}$. The McNeile and Michael method is adopted to extract the effective couplings in $N_f=2$ QCD for the decays.
The $N_f =3$ degenerate QCD result with physical mixing angle is also a partial quench result.
In this talk, we present a study on the behavior of $DD^โ$ scattering phase shifts at low energy using twisted boundary conditions. Although it is natural to use Lรผscherโs method for calculating the scattering phase shift between two hadrons from the energy spectra to address the properties of multiquark states, it is not realistic to calculate a high-resolution scattering phase shift using...
The nature of the lightest open-charm mesons in the scalar ($J^P=0^+$) sector remains elusive despite many years of studies. These mesons do not appear to have properties in line with expectations and many possible explanations have been proposed. In this talk, we report on a study where finite-volume spectra obtained from lattice QCD were used with the Lรผscher method to provide constraints on...
We present progress in the determination of glueball masses and scattering parameters computed using lattice $SU(3)$ Yang-Mills theory. Focusing on the vacuum-quantum-number ($J^{PC} = 0^{++}$) sector, the computation makes use of a number of techniques to improve the extraction of energies from Euclidean correlators, including anisotropic lattices, the multi-level algorithm, and a large set...
The first determination of doubly-charmed isospin-0 coupled-channel $DD^\ast-D^\ast D^\ast$ scattering amplitudes from lattice QCD is presented. The finite-volume spectrum is computed for three lattice volumes with a light-quark mass corresponding to $m_\pi\approx 391$ MeV and is used to extract the scattering amplitudes in $J^P = 1^+$ via the L\"{u}scher quantization condition. By...
Analyzes of astrophysical data provide hints on the self-interactions of dark matter at low energies. Lattice calculations of strongly interacting dark matter (SIMP) theories are needed for motivating these models also from first principles. Sp(4) gauge theory with two fundamental fermions is a candidate SIMP theory. We compute the scattering phase shift for the scattering of two dark pions...
The spectroscopy of open-charm mesons offers new insights into the dynamics of low-energy QCD and a point to connect with both experiment and EFT calculations.
In this talk I present the first extraction of the lowest axial-vector and tensor D-meson resonances from a coupled $D^*\pi$, $D^*\eta$ and $D_s^* \bar{K}$ scattering calculation in $N_f=2+1$ lattice QCD at a pion mass of 391 MeV. The...
In this talk, we present results on the dependence of meson-meson scattering observables on number of colors, $N_\mathrm{c}$. We work in a theory with $N_\mathrm{f}=4$ degenerate light quark flavors, and run lattice simulations with varying $N_\mathrm{c}=3-6$ and pion mass $M_\pi\approx590$ MeV. We focus on three different scattering channels, two of which possess the quantum numbers of some...
We study the $S$-wave $D\bar{D}^*(I=0)$ scattering at four different pion masses $m_\pi$ ranging from 250 MeV to 417 MeV from $N_f=2$ lattice QCD. There exists a state below $D\bar{D}^*$ threshold, which can be related to $X(3872)$ and can be either a bound state or a virtual state up to the analysis strategies applied. This observation is likely unaffected by the possible left-hand cut effect...
We calculate the decay rate for the $\eta_b$ meson to two photons for the first time in lattice QCD, building on our previous accurate calculation of the rate for $\eta_c\to\gamma\gamma$. Using the Highly Improved Staggered Quark formalism for valence and sea quarks, we work at lattice spacings from 0.12 fm down to 0.03 fm. Gluon configurations with the effect of $u,$ $d,$ $s$ and $c$ quarks...
We develope a new method to calculate hadron spectrum including isospin breaking effect on lattice, where we treat ud quark mass spltting and QED effect perturbatively. In this method we define a new value related to a certain hadron mass. This value is irrelevant to quark mass to the first order so that the renormalization of quark mass is no longer needed. We apply this method on a real...
In this talk, we discuss an issue related to the left-hand cut in the scattering amplitude, which has been recently pointed out to be relevant for an analysis on the nature of the tetra quark state $T_{cc}$.
We first discuss a relation between the left-hand cut from the Yukawa potential in non-relativistic quantum field theory and $t$-channel cut in the S-matrix for a relativistic quantum...
Sea-quark isospin-breaking effects (IBE) are difficult to compute since they require the evaluation of all-to-all propagators. However, the quest for high-precision calculations motivates a detailed study of these contributions. There are theoretical arguments that the stochastic error associated with these quantities should diverge in the continuum and infinite-volume limit, resulting in a...
The Lรผscher scattering formalism is a popular method which allows the extraction of two-to-two scattering amplitudes from the finite-volume spectrum. Recent lattice calculations have highlighted the limitations of the formalism in systems in which a lighter particle can be exchanged between the two scatterers (e.g. $NN$ or $DD^*$ scattering). This leads to the presence of a left-hand cut just...
Long-range forces are present in different systems which are studied on the lattice. For example, the role of the long-range force is very prominent in extracting the properties of the $T_{cc}^+\,(3875)$-meson from lattice data. Furthermore, the one-pion exchange provides a very significant contribution to the nucleon-nucleon scattering. In the presence of such a long-range interaction, the...
In the RC* collaboration, we simulate lattice QCD+QED using C-periodic spatial boundary conditions to ensure locality, gauge invariance, and translational invariance are preserved throughout the calculation. In this talk, we present progress in computing isospin-breaking (IB) corrections to the leading hadronic contribution to $(g - 2)_ฮผ$. We compare two ways of computing the IB corrections:...
We present a lattice calculation of dibaryons composed of single-flavor quarks, specifically focusing on baryons made up of either charm or strange quarks. We utilize various set of lattice QCD ensembles with $N_f=2+1+1$ dynamical HISQ fields, two spatial volumes, and three different lattice spacings generated by MILC collaboration. By using an overlap action for the valence charm and strange...
A previous calculation of the binding energy of the H dibaryon in SU(3)-flavour-symmetric lattice QCD showed unexpectedly large discretization effects. To better understand this, we have repeated the calculation using different lattice actions based on $N_f=3$ ensembles from CLS and OpenLat and newly generated $N_f=3+1$ ensembles with highly improved staggered quarks. Results will be shown for...
Quantum chromodynamics (QCD) is the driving mechanism behind the binding of quarks and gluons into nucleons and nuclei. Though rich in physics, the nonperturbative nature of QCD stymies the direct formulation of nuclear physics using quark and gluon degrees of freedom. Instead, perturbative approaches such as chiral effective theory that use pions and nucleons as degrees of freedom have become...
We present a study using the distillation method to analyze the spectra of nucleon, nucleon-pion, and nucleon-pion-pion states in the positive parity sector as well as nucleon and nucleon-pion states in the negative sector. The study involves using five domain wall fermion ensembles with varying pion masses ($m_\pi = 139 - 279 \text{ MeV}$), lattice spacings ($a^{-1} = 1.730 \text{ GeV}$ and...
Chiral unitary models predict an interchange of the two trajectories of the $\Lambda(1380)$ and the $\Lambda(1405)$ away from the SU(3) limit at next-to-leading order. Recently the BaryonScattering collaboration has performed a coupled channel ($\pi\Sigma-\bar{K}N$) lattice spectral analysis in the region of $\Lambda(1405)$ for $m_\pi~\sim 200$MeV pion mass. In the present contribution we...
We perform a numerical study in lattice QCD on $\Lambda(1405)$ in the flavor SU(3) limit. One of the most promising interpretations of $\Lambda(1405)$ is the so-called two-pole structure: the spectrum corresponding to $\Lambda(1405)$ observed in experiments may be explained by two poles. In order to elucidate such a property from lattice QCD, we calculate the HAL QCD potentials for the...
In this study, we develop a deep learning method to learn hadron interactions from Lattice QCD calculated correlations unsupervisedly. We present our approach of using neural networks to model potential functions that are learned from Nambu-Bethe-Salpeter (NBS) wave functions. This allows most general forms of interaction potentials to be incorporated into a Schrรถdinger-like equation for...
The investigation of hadron interactions within lattice QCD has been facilitated by the well-known quantisation condition, linking scattering phase shifts to finite-volume energies. Additionally, the ability to utilise systems at finite total boosts has been pivotal in smoothly charting the energy-dependent behaviour of these phase shifts. The existing implementations of the quantization...
The distillation method in lattice QCD is a smearing method that uses the eigenvectors of the spatial Laplacian to construct an $N$-dimensional subspace in which the Dirac operator can be fully inverted. This approach works well for nonlocal operators such as meson-meson or baryon-baryon interpolators. But when studying exotic hadrons we also want to include local multiquark interpolators with...
Calculations in lattice QCD are typically carried out in Euclidean time. Many quantities of physical interest require analytic continuation from Euclidean to Minkowski spacetime. This Wick rotation enacting a spectral reconstruction presents a difficult challenge in numerical inversion. We report on work to replicate the calculation by Alexandrou, et al. of the smeared R-ratio from lattice...
For long distances in the euclidean time the vector meson () propagator has an exponentially decreasing signal-to-noise ratio.
However, the vector correlator not only consists of the vector meson but also of the propagator of a two-pion system with the same quantum numbers. We measure all two-pion propagators with an energy lower than the mass of the resting vector meson and employ a...
The primary goal of this project is the reconstruction of quarkonium spectral functions from thermal lattice correlators, relevant for the study of Quark-Gluon Plasma in heavy-ion collisions. To this end, we pursue the generation of fully dynamical anisotropic HISQ ensembles, aiming at a physical strange quark and a heavier-than-physical light quark mass, corresponding to a 300 MeV continuum...
