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Antje Peters

Publications and source records attributed to Antje Peters.

13 recordsLinked to original sources
arXiv2021

Comparing meson-meson and diquark-antidiquark creation operators for a $\bar b \bar b u d$ tetraquark

We compare two frequently discussed competing structures for a stable $\bar b \bar b u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ by considering a meson-meson as well as a diquark-antidiquark creation operator. We treat the heavy antiquarks as static with fixed positions and find diquark-antidiquark dominance for $\bar b \bar b$ separations $r < 0.2 \, \text{fm}$, while for $r > 0.5 \, \text{fm}$ the system essentially corresponds to a pair of $B$ mesons. For the meson-meson to diquark-antidiquark ratio of the tetraquark we obtain around $58\%/42\%$.

hep-lat↗
arXiv2021

Importance of meson-meson and of diquark-antidiquark creation operators for a $\bar{b} \bar{b} u d$ tetraquark

In recent years, the existence of a hadronically stable $\bar{b} \bar{b} u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ was confirmed by first principles lattice QCD computations. In this work we use lattice QCD to compare two frequently discussed competing structures for this tetraquark by considering meson-meson as well as diquark-antidiquark creation operators. We use the static-light approximation, where the two $\bar{b}$ quarks are assumed to be infinitely heavy with frozen positions, while the light $u$ and $d$ quarks are fully relativistic. By minimizing effective energies and by solving generalized eigenvalue problems we determine the importance of the meson-meson and the diquark-antidiquark creation operators with respect to the ground state. It turns out, that the diquark-antidiquark structure dominates for $\bar{b} \bar{b}$ separations $r < 0.25 \, \text{fm}$, whereas it becomes increasingly more irrelevant for larger separations, where the $I(J^P) = 0(1^+)$ tetraquark is mostly a meson-meson state. We also estimate the meson-meson to diquark-antidiquark ratio of this tetraquark and find around $60\% / 40\%$.

hep-lat↗
arXiv2018

$\bar{b}\bar{b}ud$ tetraquark resonances in the Born-Oppenheimer approximation using lattice QCD potentials

We study tetraquark resonances using lattice QCD potentials for a pair of static antiquarks $\bar{b}\bar{b}$ in the presence of two light quarks $ud$. The system is treated in the Born-Oppenheimer approximation and we use the emergent wave method. We focus on the isospin $I=0$ channel, but consider different orbital angular momenta $l$ of the heavy antiquarks $\bar{b}\bar{b}$. We extract the phase shifts and search for $\mbox{S}$ and $\mbox{T}$ matrix poles on the second Riemann sheet. For orbital angular momentum $l=1$ we find a tetraquark resonance with quantum numbers $I(J^P)=0(1^-)$, resonance mass $m=10576^{+4}_{-4} \, \textrm{MeV}$ and decay width $Γ= 112^{+90}_{-103} \textrm{MeV}$, which can decay into two $B$ mesons.

hep-lat↗
arXiv2017

Tetraquark resonances computed with static lattice QCD potentials and scattering theory

We study tetraquark resonances with lattice QCD potentials computed for two static quarks and two dynamical quarks, the Born-Oppenheimer approximation and the emergent wave method of scattering theory. As a proof of concept we focus on systems with isospin $I = 0$, but consider different relative angular momenta $l$ of the heavy $b$ quarks. We compute the phase shifts and search for $\mbox{S}$ and $\mbox{T}$ matrix poles in the second Riemann sheet. We predict a new tetraquark resonance for $l = 1$, decaying into two $B$ mesons, with quantum numbers $I(J^P) = 0(1^-)$, mass $m = 10576_{-4}^{+4} \, \textrm{MeV}$ and decay width $Γ= 112_{-103}^{+90} \, \textrm{MeV}$.

hep-lat↗
arXiv2017

$u d \bar{b} \bar{b}$ tetraquark resonances with lattice QCD potentials and the Born-Oppenheimer approximation

We study tetraquark resonances with lattice QCD potentials computed for a static bbar bbar pair in the presence of two lighter quarks u d, the Born-Oppenheimer approximation and the emergent wave method. As a proof of concept we focus on the system with isospin I = 0, but consider different relative angular momenta l of the heavy quarks bbar bbar. For l=0 a bound state has already been predicted with quantum numbers I(JP) = 0(1+). Exploring various angular momenta we now compute the phase shifts and search for S and T matrix poles in the second Riemann sheet. We predict a tetraquark resonance for l =1, decaying into two B mesons, with quantum numbers I(JP) = 0(1-), mass m = 10 \, 576^{+4}_{-4} MeV} and decay width Gamma = 112^{+90}_{-103} MeV.

hep-lat↗
arXiv2016

Lattice QCD study of heavy-heavy-light-light tetraquark candidates

We investigate heavy-light four-quark systems $ud\bar b \bar b$ with bottom quarks of finite mass which are treated in the framework of NRQCD. We focus on $I(J^P)=0(1^+)$, where we recently found evidence for the existence of a tetraquark state using static bottom quarks. Furthermore, we report on an investigation of the $u \bar d b \bar b$ four-quark system with quantum numbers $I(J^P)=1(1^+)$ again using static bottom quarks.

hep-lat↗
arXiv2016

Investigation of $B\bar B$ four-quark systems using lattice QCD

We investigate $B \bar B$ systems by computing potentials of two static quarks in the presence of two quarks of finite mass using lattice QCD. By solving the Schrödinger equation we check whether these potentials are sufficiently attractive to host bound states. Particular focus is put on the experimentally most promising bottomonium-like tetraquark candidate $Z_b^\pm$ with quantum numbers $I(J^P)=1(1^+)$.

hep-lat↗
arXiv2015

BB interactions with static bottom quarks from Lattice QCD

The isospin, spin and parity dependent potential of a pair of $B$ mesons is computed using Wilson twisted mass lattice QCD with two flavours of degenerate dynamical quarks. The $B$ meson is addressed in the static-light approximation, i.e.\ the $b$ quarks are infinitely heavy. From the results of the $B\,B$ meson-meson potentials, a simple rule can be deduced stating which isospin, spin and parity combinations correspond to attractive and which to repulsive forces. We provide fits to the ground state potentials in the attractive channels and discuss the potentials in the repulsive and excited channels. The attractive channels are most important since they can possibly lead to a bound four-quark state, i.e.\ a $\bar{b}\bar{b}ud$ tetraquark. Using these attractive potentials in the Schrödinger equation, we find indication for such a tetraquark state of two static bottom antiquarks and two light $u/d$ quarks with mass extrapolated down to the physical value.

hep-lat↗
arXiv2015

Exploring possibly existing $q q \bar b \bar b$ tetraquark states with $q q = ud, ss, cc$

We compute potentials of two static antiquarks in the presence of two quarks $qq$ of finite mass using lattice QCD. In a second step we solve the Schrödinger equation, to determine, whether the resulting potentials are sufficiently attractive to host a bound state, which would indicate the existence of a stable $q q \bar b \bar b$ tetraquark. We find a bound state for $qq=(ud-du)/\sqrt{2}$ with corresponding quantum numbers $I(J^ P)=0(1^+)$ and evidence against the existence of bound states with isospin $I=1$ or $qq \in \{cc,ss \}$

hep-lat↗
arXiv2015

Evidence for the existence of $u d \bar{b} \bar{b}$ and the non-existence of $s s \bar{b} \bar{b}$ and $c c \bar{b} \bar{b}$ tetraquarks from lattice QCD

We combine lattice QCD results for the potential of two static antiquarks in the presence of two quarks $q q$ of finite mass and quark model techniques to study possibly existing $q q \bar{b} \bar{b}$ tetraquarks. While there is strong indication for a bound four-quark state for $q q = (ud-du) / \sqrt{2}$, i.e. isospin $I=0$, we find clear evidence against the existence of corresponding tetraquarks with $q q \in \{ uu , (ud+du) / \sqrt{2} , dd \}$, i.e. isospin $I=1$, $q q = s s$ and $q q = c c$.

hep-lat↗
arXiv2014

$Λ_{\bar{\textrm{MS}}}^{(n_f=2)}$ from a momentum space analysis of the quark-antiquark static potential

We determine $Λ_{\bar{\textrm{MS}}}^{(n_f=2)}$ by fitting perturbative expressions for the quark-antiquark static potential to lattice results for QCD with $n_f=2$ dynamical quark flavors. To this end we use the perturbative static potential at the presently best known accuracy, i.e. up to ${\cal O}(α_s^4)$, in momentum space. The lattice potential is computed on a fine lattice with $a \approx 0.042 \, \textrm{fm}$ in position space. To allow for a comparison and matching of both results, the lattice potential is transformed into momentum space by means of a discrete Fourier transform. The value of $Λ_{\bar{\textrm{MS}}}^{(n_f=2)}$ is extracted in momentum space. All sources of statistical and systematic errors are discussed. The uncertainty in the value of $Λ_{\bar{\textrm{MS}}}^{(n_f=2)}$ is found to be smaller than that obtained in a recent position space analysis of the static potential based on the same lattice data.

hep-ph↗
arXiv2012

Interaction of the pseudoscalar glueball with (pseudo)scalar mesons and nucleons

We study the interactions of the pseudoscalar glueball with scalar and pseudoscalar quark-antiquark meson fields and with the nucleon and its chiral partner. In both cases we introduce the corresponding chiral Lagrangian and discuss its properties. We calculate the mesonic and baryonic decays of a pseudoscalar glueball with mass of about 2.6 GeV as predicted by Lattice simulations.

hep-ph↗