Search results for "Bound state"

Deeply bound levels in kaonic atoms

2000

Using a microscopic antikaon-nucleus optical potential recently developed by Ramos and Oset (nucl-th/9906016, in print in Nuclear Physics A) from a chiral model, we calculate strong interaction shifts and widths for $K^-$ atoms. This purely theoretical potential gives an acceptable description of the measured data ($\chi^2/{\rm num.data}= 3.8$), though it turns out to be less attractive than what can be inferred from the existing kaon atomic data. We also use a modified potential, obtained by adding to the latter theoretical one a s-wave term which is fitted to known experimental kaonic data ($\chi^2/{\rm degree of freedom}= 1.6$), to predict deeply bound $K^-$ atomic levels, not detected y…

Quasielastic proton knockout from 16O.

1994

The spectral function of the $^{16}\mathrm{O}$(e,e'p${)}^{15}$N reaction has been measured in quasielastic parallel kinematics. Momentum distributions are extracted for transitions to several discrete states, with emphasis on the low-lying positive parity states of $^{15}\mathrm{N}$. Spectroscopic factors and bound state wave functions are deduced from a DWIA analysis employing five different optical potentials. Coupled channels effects are investigated for the first four states of $^{15}\mathrm{N}$ and are found to be minimal. The spectroscopic results of the 1/${2}^{\mathrm{\ensuremath{-}}}$ ground state and the first 3/${2}^{\mathrm{\ensuremath{-}}}$ excited state indicate a 28%\ifmmode\…

Unraveling the pattern of the XYZ mesons

2014

We present a plausible mechanism for the origin of the $XYZ$ mesons in the heavy meson spectra within a standard quark-model picture. We discuss the conditions required for the existence of four--quark bound states or resonances contributing to the heavy meson spectra, being either compact or molecular. We concentrate on charmonium and bottomonium spectra, where several new states, difficult to understand as simple quark-antiquark pairs, have been reported by different experimental collaborations. The pivotal role played by entangled meson-meson thresholds is emphasized.

LHCb pentaquarks in constituent quark models

2016

The recently discovered $P_c(4380)^+$ and $P_c(4450)^+$ states at LHCb have masses close to the $\bar D\Sigma_c^*$ and $\bar D^*\Sigma_c$ thresholds, respectively, which suggest that they may have significant meson-baryon molecular components. We analyze these states in the framework of a constituent quark model which has been applied to a wide range of hadronic observables, being the model parameters, therefore, completely constrained. The $P_c(4380)^+$ and $P_c(4450)^+$ are studied as molecular states composed by charmed baryons and open charm mesons. Several bound states with the proper binding energy are found in the $\bar D\Sigma_c^*$ and $\bar D^*\Sigma_c$ channels. We discuss the pos…

Lattice QCD study of the $H$ dibaryon using hexaquark and two-baryon interpolators

2019

Physical review / D 99(7), 074505 (2019). doi:10.1103/PhysRevD.99.074505

Density distributions in the $B$ meson

2016

We report on a two-flavor lattice QCD study of the axial, charge and matter distributions of the $B$ meson and its first radial excitation. As our framework is the static limit of Heavy Quark Effective Theory (HQET), taking their Fourier transform gives access to several form factors at the kinematical point $q^2=0$. Moreover they provide some useful information on the nature of an excited state, i.e. a radial excitation of a quark-antiquark bound state or a multihadron state.

Polymorphic and regular localized activity structures in a two-dimensional two-component reaction–diffusion lattice with complex threshold excitation

2010

Abstract Space–time dynamics of the system modeling collective behaviour of electrically coupled nonlinear units is investigated. The dynamics of a local cell is described by the FitzHugh–Nagumo system with complex threshold excitation. It is shown that such a system supports formation of two distinct kinds of stable two-dimensional spatially localized moving structures without any external stabilizing actions. These are regular and polymorphic structures. The regular structures preserve their shape and velocity under propagation while the shape and velocity as well as other integral characteristics of polymorphic structures show rather complex temporal behaviour. Both kinds of structures r…

2019

The atomic spectrum of neutral promethium has been studied extensively by laser resonance ionization spectroscopy. We report on more than 1000 atomic transitions in the blue and near infrared spectral ranges, most of them between high excited energy levels. As Rydberg convergences could not be assigned unambiguously in the dense spectrum at high excitation energies, the first ionization potential (IP) was determined via field ionization of weakly bound states within a static electric field. By applying the saddle-point model, a value of ${\mathrm{IP}}_{(\mathrm{Pm})}=45\phantom{\rule{0.16em}{0ex}}020.8(3)\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1} [5.58188(4)\phantom{\rule{0.16…

Quantum screened interactions in moderately dense plasmas and atomic contributions to thermodynamics

2017

Systematic analysis of the peripherality of the Be10(d,p)Be11 transfer reaction and extraction of the asymptotic normalization coefficient of Be11 bo…

2018

We reanalyze the experiment of Schmitt et al. on the $^{10}\mathrm{Be}(d,p)^{11}\mathrm{Be}$ transfer reaction [Phys. Rev. Lett. 108, 192701 (2012)] by exploring the beam-energy and angular ranges at which the reaction is strictly peripheral. We consider the adiabatic distorted wave approximation (ADWA) to model the reaction and use a Halo-EFT description of $^{11}\mathrm{Be}$ to systematically explore the sensitivity of our calculations to the short-range physics of the $^{10}\mathrm{Be}\ensuremath{-}n$ wave function. We find that by selecting the data at low beam energy and forward scattering angle the calculated cross sections scale nearly perfectly with the asymptotic normalization coef…