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Register a new user$bar{b}bar{b}ud$ tetraquark resonances in the Born-Oppenheimer approximation using lattice QCD potentials
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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 $Gamma= 112^{+90}_{-103} textrm{MeV}$, which can decay into two $B$ mesons.
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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.
We use lattice QCD to investigate the spectrum of the $bar{b} bar{b} u d$ four-quark system with quantum numbers $I(J^P) = 0(1^+)$. We use five different gauge-link ensembles with $2+1$ flavors of domain-wall fermions, including one at the physical pion mass, and treat the heavy $bar{b}$ quark within the framework of lattice nonrelativistic QCD. Our work improves upon previous similar computations by considering in addition to local four-quark interpolators also nonlocal two-meson interpolators and by performing a Luscher analysis to extrapolate our results to infinite volume. We obtain a binding energy of $(-128 pm 24 pm 10) , textrm{MeV}$, corresponding to the mass $(10476 pm 24 pm 10) , textrm{MeV}$, which confirms the existence of a $bar{b} bar{b} u d$ tetraquark that is stable with respect to the strong and electromagnetic interactions.
We determine hadronic matrix elements relevant for the mass and width differences, $Delta M_s$ & $Delta Gamma_s$ in the $B^0_s - bar{B^0_s}$ meson system using fully unquenched lattice QCD. We employ the MILC collaboration gauge configurations that include $u$, $d$ and $s$ sea quarks using the improved staggered quark (AsqTad) action and a highly improved gluon action. We implement the valence $s$ quark also with the AsqTad action and use Nonrelativistic QCD for the valence $b$ quark. For the nonperturbative QCD input into the Standard Model expression for $Delta M_s$ we find $f_{B_s} sqrt{hat{B}_{B_s}} = 0.281(21)$GeV. Results for four-fermion operator matrix elements entering Standard Model formulas for $Delta Gamma_s$ are also presented.
We compute the mass-spectra of all bottom tetraquarks [$bb][bar{b}bar{b}$] and heavy-light bottom tetraquarks [$bq][bar{b}bar{q}$] (q=u,d), that are considered to be compact and made up of diquark-antidiquark pairs. The fully bottom tetraquark [$bb][bar{b}bar{b}$] has been studied in $eta_{b}(1S)eta_{b}(1S)$, $eta_{b}(1S)Upsilon(1S)$ and $Upsilon(1S)Upsilon(1S)$ S-wave channels, as well as a few orbitally excited channels, with masses ranging from 18.7 GeV to 19.8 GeV. The masses of heavy-light bottom tetraquarks are studied in the $B^{pm}B^{pm}$, $B^{pm}B^{*}$ and $B^{*}B^{*}$ channels, with masses ranging from 10.4 GeV to 10.5 GeV. Two charged resonances, $Z_{b}(10610)$ and $Z_{b}(10650)$, both with the quantum number $1^{+-}$, have also been investigated.
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 $58%/42%$.
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