Conveners
Hadronic and Nuclear Spectrum and Interactions
- Anthony Francis (National Yang Ming Chiao Tung University)
Hadronic and Nuclear Spectrum and Interactions
- Antonin Portelli (University of Edinburgh)
Hadronic and Nuclear Spectrum and Interactions
- Sinya Aoki (Yukawa Institute for Theoretical Physics)
Hadronic and Nuclear Spectrum and Interactions
- Andre Walker-Loud (LBNL)
Hadronic and Nuclear Spectrum and Interactions
- Fernando Romero-Lopez (MIT)
Hadronic and Nuclear Spectrum and Interactions
- Steve Sharpe (University of Washington)
Hadronic and Nuclear Spectrum and Interactions
- Maxwell Hansen ()
A previous calculation of baryon-baryon scattering using CLS ensembles with nonperturbatively $O(a)$-improved Wilson fermions revealed large discretization effects in the scattering amplitude. It is natural to ask whether other systems with heavy hadrons are affected. Using the same setup and adding valence charm quarks with the same action, we study $DD^*$ scattering and the $T_{cc}$...
We perform a lattice simulation to investigate the doubly charm tetraquark $T^+_{cc}$ observed by the LHCb collaboration with flavor content $cc\bar{u}\bar{d}$, isospin-$0$, and only $0.4$ MeV below the $D^{*+}D^0$ threshold. We implement two-meson interpolators, and additionally also diquark-antidiquark interpolators. This is the first extraction of the scattering amplitude from correlators...
The doubly charmed tetraquark $T_{cc}^+$ recently discovered by the LHCb collaboration is studied on the basis of (2 + 1)-flavor lattice QCD simulations of $D^*D$ system with nearly physical pion mass $m_\pi = 146$ MeV. The interaction of $D^* D$ in the isoscalar and $S$-wave channel, derived from the hadronic spacetime correlation by the HAL QCD method, is attractive for all distances and...
The study of doubly heavy tetraquarks has gained substantial topical interest, primarily boosted by the recent discovery of doubly charmed tetraquark $T_{cc}$ and by its phenomenological prospects. While $T_{cc}^+$ is observed to be $\sim$0.4 MeV below the $DD^*$ threshold, multiple lattice calculations point to a deep binding ($\mathcal{O}(100 MeV)$) in $T_{bb}$. However, the predictions for...
In this talk, we present preliminary results on $\pi\pi$ and $\rho\rho$ coupled-channel scattering with 4 degenerate light quark flavors. We focus on different scattering channels, two of which are attractive and possess the same quantum numbers as the two $X_{0,1}(2900)$ tetraquark candidates recently discovered at LHCb. Using Luscher's formalism, we investigate these resonances in the...
We calculate the leading-order QED corrections to meson masses and bare quark masses. As lattice QCD calculations become more precise, these QED corrections are becoming more important. However, one of the challenges in adding QED effects to QCD calculations is avoiding power-law suppressed finite volume effects. These effects can enter calculations of many observables because QED has massless...
We give an update on an ongoing project in which we calculate the masses of octet and decuplet baryons including isospin-breaking effects. To this end, we employ single- and two-state-fits to effective masses at leading and sub-leading order in the expansion in isospin-breaking parameters. In order to remove objective bias on asymptotic masses we furthermore compute an AIC-based model-average...
The $\Lambda(1405)$ resonance is listed in PDG as a strangeness $S=-1$ baryon with quantum numbers $I(J^P)=0(\frac{1}{2}^-)$. However, most models based on chiral effective theory and unitary suggest two nearby overlapping resonance poles. This two-pole picture for the $\Lambda(1405)$ is disputed by recent phenomenological fits to experimental data which require only a single pole, and...
We perform a numerical study in lattice QCD on $\Lambda(1405)$, an excited $\Lambda$ baryon whose existence is not well explained by the quark model. Since the previous studies using the chiral unitary model suggest that $\Lambda(1405)$ may be explained by two poles in the octet and the singlet channels of the flavor SU(3), we calculate the HAL QCD potentials for the meson-baryon systems in...
We present updated results of the excited and exotic spectra of $B, B_s$ and $B_c$ mesons. The calculations are performed on dynamical, anisotropic lattices with relativistic heavy quarks. A first look at finite volume effects and next steps are also discussed.
We use the method of optimal distillation profiles to compute the low-lying charmonium spectrum in an $N_f = 3+1$ ensemble at the $SU(3)$ light flavor symmetric point ($m_{\pi} \approx 420$ MeV), physical charm quark mass and lattice spacing $a\approx 0.0429$ fm. The spectrum and mass splittings display good agreement with their values in nature and the statistical errors are comparable, if...
It has been demonstrated that distillation profiles can be employed
to build optimized quarkonium interpolators for spectroscopy calculations
in lattice QCD. We test their usefulness for heavy-light systems on
(3+1)-flavor ensembles with mass-degenerate light and a charm quark in
the sea in preparation for a future DDbar-scattering analysis.
The additional cost of light inversions...
Experimentally many exotic charmonium-like mesons have already been discovered, for example, the $Z_c$ mesons. We study the spectrum of such states with isospin 1 focusing on the $\bar cc \bar qq$ channels with $J^{P}=1^{+}$, $C=\pm$. This is the first study of four-quark states with these quantum numbers, where the total momentum is non-zero. The simulations are performed on two...
We present preliminary results of lattice QCD calculations for $D\pi$ scattering with isospin-$\frac{1}{2}$ and $\frac{3}{2}$. Using newly generated $N_f=2+1$ Wilson-Clover configurations by the CLQCD collaboration, we examine two volume extents ($L^3 \times T=32^3 \times 96$ and $48^3 \times 96$) at the same lattice spacing ($a=0.080$ fm) with a pion mass of $m_\pi \approx 290$ MeV. Employing...
We present preliminary results for the $\rho(770)$ and $K^*(892)$ resonances using the Lüscher method. This work employs distillation on an RBC-UKQCD $N_f=2+1$ domain-wall fermion lattice with a physical pion mass. We consider irreducible representations with only leading $P-$wave contributions and extract the associated low-lying energy levels. These are used to parametrise the scattering...
The excited states contamination in the nucleon three-point function is one of the major systematic errors in calculating nucleon form factors. We use Bayesian Reconstruction to study the nucleon excited states in the two-point nucleon and S11 correlators which are constructed from the valence overlap fermions on DWF configurations at the physical pion mass with a lattice size of 5.5 fm. We...
We present an analysis of the $N \pi$ contribution to the determination of the nucleon mass spectrum using constrained fits. Our study involves simultaneous fitting of $N \to N$ and $N \to N \pi$ correlation functions. The analysis is performed on a $24^3 \times 48 \times 24$ lattice with $2 + 1$ dynamical Domain-Wall fermions. We employ a lattice spacing of $a^{-1} = 1.74 \text{ GeV}$ and a...
Neutrino oscillation experiments require accurate reconstructions of neutrino energies, which depend in part on a theoretical understanding of the axial $N \rightarrow \Delta$ transition form factors. A lattice QCD study of this transition will require construction of all hadronic states with energies up to $m_\Delta$, which at the physical point includes $N\pi$ and $N\pi\pi$. Building...
Studies of the $\Delta$ baryon resonance and the $K_0^\ast(700)$ and $a_0(980)$ meson resonances using $N_f=2+1$ lattice QCD for pion masses near 200 MeV are presented. The role of tetraquark operators in the mesonic systems is detailed. The $s$-wave scattering lengths for both the $I=1/2$ $N \pi$ and $I=3/2$ $N \pi$ channels and properties of the $\Delta$ resonance are identified from the...
The Lüscher formalism is a well-known and widely used method for extracting scattering amplitudes from the finite-volume spectrum. Recent lattice QCD calculations involving systems where a lighter particle couples to heavier scattering particles (e.g. baryon-baryon scattering) have highlighted the limitations of the standard formalism below threshold. This is due to the presence of left-hand...
Understanding three-body dynamics is crucial in comprehending the behavior of hadronic states that decay into three or more particles under strong interactions. Recent advances in Lattice QCD techniques allow us to calculate three-particle interactions from QCD and access finite volume energies. Connecting these energies to physical observables involves multiple steps. Firstly, we use the...
The recently discovered I = 0, JP = 1+ doubly-charmed tetraquark Tcc(3875) is an exotic meson that is a candidate for a DD molecule. In nature, it decays to DDπ, since the D is unstable. It has been studied on the lattice for heavier-than-physical quark masses for which the D* is stable, so that two-particle methods can be used. However, a major drawback of this methodology is that the...
The K-matrix parametrizes short-range interactions in the relativistic-field-theory finite-volume formalism. It is related to the infinite-volume scattering amplitude, thus providing a bridge between the lattice and perturbation theory, as well as a handle on finite-volume effects and the pion mass dependence. However, leading-order perturbative calculations agree very poorly with the results...
Many hadronic resonances, including the most intriguing ones (Roper, $\pi_1$(1600), or $T^+_{cc}$(3872)), decay into three or more particles. In principle, one can determine their properties from the multi-body version of the Luscher finite-volume scattering formalism. However, one of the obstacles in specifying their masses from Lattice QCD is the lack of developed three-body amplitude...
We generalize the relativistic field-theoretic (RFT) three-particle finite-volume formalism to systems of three identical, massive, spin-$1/2$ fermions, such as three neutrons. This allows, in principle, for the determination of the three-neutron interaction from the finite-volume spectrum of three-neutron states, which can be obtained from lattice QCD calculations.
We present results for O(1/m) and O(1/m^2) relativistic corrections to the static potential. The potentials are computed using Wilson loops with two colour-field insertions. To renormalize the inserted fields, we applied Gradient flow to the correlator. This also leads to a significant improvement of the signal-to-noise ratio, providing access to loops with large spatial and temporal extent.
We present results for the potential of two static anti-quarks in the presence of two light quarks. We improve on existing results the $\bar b \bar b u d$ tetraquark system by computing the static potential at off-axis separations, significantly increasing the number of data points in the crucial region of small distances. Moreover, we show entirely new results for the static potential of a...
We present a method for computing hybrid static quark-antiquark potentials in lattice QCD based on Laplace trial states. They are formed by eigenvector components of the covariant lattice Laplace operator and their covariant derivatives. The new method does not need complicated gauge link paths between the static quarks and makes off-axis separations easily accessible. We show first results...
The nucleon-hyperon interaction is important to understand the system with strange quarks, for example, the inner region of neutron stars. Although experimental study of the interaction is difficult rather than the nucleon-nucleon interaction, which is so-called nuclear force, theoretical study is possible by using the HAL QCD method in the lattice QCD. In the present contribution, we show our...
I discuss our progress in studying the two-nucleon spectrum at heavy pion mass using various types of interpolating operators to create the correlation functions. These include momentum-space creation and annihilation operators using the stochastic Laplacian Heaviside method both with and without local hexa-quark interpolators, local hexa-quark creation operators and momentum space...
I will present updated results from the NPLQCD collaboration including a variational study of $NN$ systems at $m_\pi\sim800$MeV on two lattice volumes, using a set of interpolating operators that includes non-local products of plane-wave baryons as well as operators spanning the full Hilbert space of local six-quark operators. I will also show a first glance at the results of the same analysis...
The continued generation of $n_f=2+1$ quark flavor gauge configurations using stabilized Wilson fermions by the open lattice initiative (OpenLat) is reported. We present the status of our ongoing production and show updates on increasing statistics at the four lattice spacings $a=0.12, 0.094, 0.077$ and $0.064$ fm. Aside from the flavor symmetric point we discuss advancements in going towards...
The fate of heavy quarkonia states in quark-gluon plasma is encoded in the temperature dependence of their spectral functions. Reconstruction of spectral functions from Euclidean lattice correlators is an ill-posed problem. Despite a variety of techniques developed recently, many questions remain unresolved. It is known that the situation may be improved using anisotropic ensembles that...
Recently, formalism has been derived for obtaining the physical amplitudes for $\gamma^\star \to3\pi$, $K \to3\pi$, and other electroweak three-body decays, from finite-volume matrix elements, which can be obtained from lattice QCD calculations of three-point correlation functions. The relation between the finite-volume quantities and the desired infinite-volume amplitudes requires solving...
We perform a lattice QCD calculation to study the behavior of the electromagnetic form factor of the pion, both in the spacelike and timelike region. At the heavier than physical pion mass of 284 MeV of this lattice, the rho meson is a narrow resonance that drives the pion-pion P-wave elastic interaction. As a preamble for future work studying the timelike form factor in the coupled channel...
Standard lattice calculations of the glueball spectrum rely on effective mass plots and asymptotic exponential fits of two-point correlators, and involve various numerical challenges.
In this work, we propose an alternative procedure to extract glueball masses, based on the computation of the smeared spectral densities that encode information about the towers of states with given quantum...