Conveners
Hadronic and nuclear spectrum and interactions
- Urs Heller (Physical Review D, American Physical Society)
Hadronic and nuclear spectrum and interactions
- Maxim Mai (University of Bern)
Hadronic and nuclear spectrum and interactions
- Felix Benjamin Erben
Hadronic and nuclear spectrum and interactions
- Fernando Romero Lรณpez (Uni Bern)
Hadronic and nuclear spectrum and interactions
- Srijit Paul
Hadronic and nuclear spectrum and interactions
- Jeremy Green (DESY, Zeuthen)
Hadronic and nuclear spectrum and interactions
- Amy Nicholson (UNC Chapel Hill)
Hadronic and nuclear spectrum and interactions
- Robert Perry (Massachusetts Institute of Technology)
We present the most precise determination to date of the ground-state masses of the triply charmed baryons with both parities, obtained by continuum extrapolation from two complementary lattice setups and thus fully addressing the systematic uncertainties. The calculations are performed on six $N_f=2+1+1$ HISQ ensembles generated by the MILC collaboration. In the valence sector we use HISQ...
We present preliminary lattice QCD results for the ground-state spectrum of hadrons containing bottom, charm, and strange quarks. Using relativistic highly improved staggered quarks (HISQ) for all three flavorsโbottom, charm, and strangeโon $2{+}1{+}1$ ensembles, we compute meson and spin-$3/2$ baryon masses. While some states have been observed experimentally, much in the bottom sector...
The masses of the lowest charmonium states are determined on a set of over 50 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, whereas various combinations of pion and kaon masses cover the quark mass plane, with the pion mass...
We study the mass spectra of heavy hadrons containing one or more bottom quarks, along with their hyperfine splittings and mass differences, using MILC's Nf = 2+1+1 HISQ gauge ensembles at three lattice spacings. To simulate the valence quark flavors, we employ a combination of lattice actions adapted to their masses: the NRQCD action is used for bottom quarks, the anisotropic Clover action is...
We investigate the mixing between S-wave flavor-singlet light meson and charmonium operators in two $N_f = 3 + 1$ ensembles at different pion masses ($m_{\pi} \approx 420, 800$ MeV). By solving a GEVP we find both types of operators have non-zero overlaps with all states we look at. We also compare the resulting spectrum with the one coming from separate GEVPs including either only light meson...
I will summarize various lattice investigations of charmed and charmonium tetraquarks using CLS lattice QCD ensembles that we have performed in the past one year.
In this work, we investigate the possible existence of a strange partner of the $T_{cc}$ tetraquark with flavor content $cc\bar{u}\bar{s}$ using lattice QCD. We determine the coupled-channel $DD_s^* - D^*D_s$ scattering amplitudes in the axialvector ($J^P = 1^+$) channel, as well as the elastic $DD_s$ scattering amplitude in the scalar ($J^P = 0^+$) channel. The calculations are performed on...
The doubly charmed tetraquark $T_{cc}(3875)^+$ observed at LHCb has attracted considerable interest in recent years. To accurately determine its finite-volume spectrum, a variational analysis using a large basis of operators, including bilocal scattering operators but also local tetraquark operators, should be used. Using Wilson-clover fermions at the $SU(3)$-flavour-symmetric point, we...
The recent discovery of $T_{cc}$ has attracted several lattice QCD
as well as other studies of $T_{cc}$ pole. Though for $T_{bb}$ there
is a consensus about the existence of a deeply bound state, no such
consensus have been reached for $T_{cc}$. On top of that the discovery
of Left Hand Cut made the pole analysis using Lรผscherโs method
difficult. In this situation it is desirable to study...
We present our recent investigation on doubly bottom and bottom-strange tetraquarks in the isoscalar channel in search of a possible tetraquark bound state. The calculations are performed on four ensembles with dynamical quark fields up to the charm quark generated by the MILC Collaboration with various lattice spacings. Multiple volumes have been used to account for finite volume effects....
In this work we investigate the time-like pion form factor from lattice QCD, a quantity interesting for its physics content and its phenomenological reach. This observable can be calculated in the elastic region using the finite-volume approach, up to the first (four-particle) open channel. With the goal of accessing the exclusive two-pion form factor in the inelastic region, starting from a...
Scattering processes featuring the strong interactions can be studied using lattice QCD by means of the Lรผscher formalism. This approach relies on analyticity and unitarity of the $S$-matrix to relate infinite-volume scattering amplitudes to finite-volume energy levels. However, lattice QCD simulations employing rooted staggered fermions manifest unitarity violation as an $\mathcal{O}(a^2)$...
Resonant hadrons, and some loosely bound states, can be studied by looking at the energy dependence of the reaction rate of the multi-particle asymptotic states associated to them. For instance, the form factors of these states can be found via analytic continuation of the two-particle transition rate induced by the current of interest. These transitions, in turn, can be constrained from...
We present a novel procedure for analyzing the lattice-QCD spectrum via the finite-volume formalism to obtain constraints on multi-hadron scattering amplitudes at both real and complex energies. This approach combines a Bayesian reconstruction of the scattering amplitude on the real axis with Nevanlinna interpolation for analytic continuation to complex-valued energies. The method is...
Four-particle intermediate and final states pose major challenges for lattice calculations of scattering and decay amplitudes, as well as long-distance matrix elements. As a step toward addressing these challenges, we present preliminary results from a perturbative study of four-pion effects in finite-volume spectra and in the relation between finite-volume matrix elements and decay...
The discovery of XYZ exotic states in the hadronic sector, particularly those containing two heavy quarks, remains one of the most intriguing open problems in particle physics. In this talk, I present the Born-Oppenheimer Effective Field Theory (BOEFT), a framework derived from QCD, capable of describing exotic hadrons of any composition. I present results on the key nonperturbative...
The pole structure of the $\Lambda(1405)$ has been a topic of debate for a long time. Chiral perturbation theory predicts that its experimental spectrum may be explained by a two pole structure originating in the $SU(3)$ chiral dynamics of the baryon-meson interaction. The $SU(3)$-symmetric flavor point is readily accessible in lattice QCD, in this work we study the baryon-meson states...
The double-pole structure of the strangeness S=-1 isoscalar baryon resonance has become a poster child for the complicated, non-perturbative structure of QCD at low energies. Traditionally, the most successful theoretical approach to study this state has been based on the extensions of Chiral Perturbation Theory. This remains so far the primary methodology underlying the pole positions quoted...
The experimentally challenging J^P=1/2^- hyperons are investigated by computing meson-baryon scattering on the lattice. An ensemble with 2+1 flavours from the CLS consortium with m_pi=285 MeV, m_K=460 MeV is employed. This is possible thanks to the stochastic Laplacian Heaviside smearing. Both single hadron and scattering operators are considered in different irreps and moving frames. We will...
Isospin-breaking corrections pose a significant challenge to lattice simulations, both because of the splitting between the up and down quark masses and, in particular, the need to include QED effects. The RC$*$ collaboration has developed the openQxD code, based on openQCD, which enables fully dynamical QCD+QED simulations through the implementation of C-periodic boundary conditions.
We use...
We present first-principles lattice QCD results for the strangeness $S = -1$ sector of baryon-baryon interactions with the physical masses for the first time. Employing the (2+1)-flavor gauge configurations (HAL-conf-2023) [1] generated on the physical point, $(m_\pi , m_K) = (137, 502)~\mathrm{MeV}$, we calculate baryon-baryon correlation functions using the supercomputer Fugaku and extract...
We present preliminary results on the $I=0$, $S=-2$ $H$ dibaryon in $N_f=2+1$ QCD. The calculation is performed with heavier-than-physical quarks ($m_\pi \approx 280$ MeV) on a single CLS ensemble. Correlation matrices are constructed using the distillation technique and the three relevant channels, $\Lambda\Lambda$, $N\Xi$, $\Sigma\Sigma$, are investigated to determine the interacting...
Excited-state effects lead to hard-to-quantify systematic uncertainties in spectroscopy calculations when imaginary times are smaller than inverse excitation gaps. The recently proposed Lanczos/Rayleigh-Ritz framework provides a set of two-sided constraints on energy levels that hold regardless of the size of excited-state effects. In this talk I discuss the application of these newly...
We present preliminary results from a lattice QCD study of the lowest energy levels of light nucleiโspecifically the deuteron, dineutron, helium-3, and helium-4 systemsโand compare those with their respective thresholds for investigating their binding energies. We utilize a set of $N_f=2+1$ flavor gauge ensembles, generated by the HotQCD Collaboration with the HISQ action at the physical sea...
We use lattice QCD calculations of the finite-volume spectra of systems of two and three mesons to determine, for the first time, three-particle scattering amplitudes with physical quark masses. Our results are for combinations of $\pi^+$ and $K^+$, at a lattice spacing $a = 0.063 ,\text{fm}$, and in the isospin-symmetric limit. We also obtain accurate results for maximal-isospin two-meson...
In this talk, I discuss an ongoing first lattice study of the doubly-charmed tetraquark $T_{cc}^+(3875)$ via a fully three-body approach. We investigate the $DD\pi$ system in the $I = 0$, $C = 2$ sector, where the $T_{cc}^+$ appears as a pole in the $J^P = 1^+$ $DD\pi$ elastic scattering amplitude. The approach automatically incorporates two-body $DD^*$ and three-body $DD\pi$ effects and...
We describe the extension of the relativistic field theoretic finite-volume formalism to $N \pi \pi$ scattering states at maximal isospin, $I=5/2$, focusing on the new features that arise in this system.
We illustrate the application of the formalism by providing a sample numerical application that includes the $\Delta$ resonance in the $N\pi$ subchannel.
We study the singularities in...
What is the pattern and mechanisms behind the labyrinthine spectrum of excited hadrons?
Many open questions in this regard hinge on a precise understanding of the three-body dynamics in continuum and in finite-volume settings. One curious case is that of the lightest hadron โ the pion โ with the mass of 1/7th of that of the nucleon. Its excited state (pi(1300)) is nearly as heavy as the...
The nature of low-lying scalar and axial-vector charmed mesons has long been debated, specifically whether they are best explained by hadronic molecular or compact tetraquark models. These two models predict quite different features for the accessible SU(3) multiplets in the scalar and axial-vector sectors.
We performed N_f=3+1 lattice simulations and calculate the energy levels of of the...
