Strong Decay Widths Research Articles

Interpretation of recently discovered single bottom baryons in the relativistic flux tube model

Following recent experimental progress in the study of bottom baryons, we systematically calculate the mass spectra of Λb, Ξb, Σb, Ξb′, and Ωb baryons with a quark-diquark picture in the framework of a relativistic flux tube model with spin-dependent interactions in the j-j coupling scheme. Furthermore, we calculate the strong decay width of bottom baryons decaying into a bottom baryon and a light pseudoscalar meson. Good agreement is found between the calculated masses and the experimentally available masses of singly bottom baryons. By analyzing both mass spectra and strong decay widths, we interpret Σb(6097) as a 1P(3/2−) state and Ξb(6100) as a 1P(1/2−) state of the Ξb baryon. The Ξb(6227) is identified to be an orbital excitation 1P of the Ξb′ baryon with JP=3/2−. Further, we determine Ξb(6327) and Ξb(6333) as a 1P(3/2−) state and 1P(5/2−) state, respectively, of Ξb′ baryon. From the obtained mass spectra, we construct the Regge trajectories in the (J,M2) plane, which are found to be essentially linear, parallel, and equidistant. Our predictions for higher orbital and radial excited states can help experimentalists identify missing excited states of singly bottom baryons. Published by the American Physical Society 2024

Detailed derivation of the $\mathbf{^3P_0}$ strong decay model applied to baryons

Abstract We provide an in-detail derivation, through the $^3P_0$ pair creation model, of the transition matrix for a baryon decaying into a meson baryon system. The meson's analysis was successfully conducted in Ref.~\cite{Segovia:2012cd} and we extend the same formalism to the baryon sector, focusing on the $\Delta(1232)\to \pi N$ strong decay width because all hadrons involved in the reaction are very well established, the two hadrons in the final state are stable avoiding further analysis, all quarks are light and so equivalent, and the decay width of the process is relatively well measured. Taking advantage of a very common Rayleigh-Ritz variational method for solving the 2- and 3-body Sch"odinger bound-state equation in which the hadron's radial wave functions are expanded in terms of a Gaussian basis, the expression of the invariant matrix element can be related with the mean-square radii of hadrons involved in the decay. We use their experimental measures in such a way that only the strength of the quark-antiquark pair creation from the vacuum is a free parameter. This is then taken from our previous study of strong decay widths in the meson sector~\cite{Segovia:2012cd}, obtaining a quite compatible result with experiment for the calculated $\Delta(1232)\to \pi N$ decay width and indicating a possible path towards a unified and global description of the baryon and meson strong decay widths within the same constituent quark model framework. Finally, this research work has been developed in setting the stage for a novel raft of applications to exotic hadrons, \emph{i.e.} the description of baryon's coupling to meson-baryon thresholds, one of the mechanism that is thought to be responsible of providing either a large renormalization to naive states or genuine dynamically-generated meson-baryon molecules.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd

Decay property of the X(3842) as the ψ3(1D33) state

In this paper, the new particle X(3842) discovered by the LHCb Collaboration is identified to be the ψ3(13D3) state. We study its strong decays with the combination of the Bethe-Salpeter method and the P30 model. Its electromagnetic (EM) decay is also calculated by the Bethe-Salpeter method within the Mandelstam formalism. The strong decay widths are Γ[X(3842)→D0D¯0]=1.27 MeV and Γ[X(3823)→D+D−]=1.08 MeV, and the ratio is B[X(3842)→D+D−]/B[X(3823)→D0D¯0]=0.84. The EM decay width is Γ[X(3842)→χc2γ]=0.29 MeV. We also estimate the total width to be 2.87 MeV, which is in good agreement with the experimental data 2.79−0.86+0.86 MeV. Since the used relativistic wave functions include different partial waves, we also study the contributions of different partial waves in electromagnetic decay. Published by the American Physical Society 2024

New Conclusions of Strong Decay Widths for η_b (5S) State via Non-Relativistic Quark Model Frame

New Conclusions of Strong Decay Widths for η_b (5S) State via Non-Relativistic Quark Model Frame

Study of the spectra and decay widths of singly heavy baryons

We present a study of the spectra and strong decay widths of singly heavy baryons. The masses of singly heavy baryons up to the D-wave are calculated within a constituent quark model, employing the three-quark and quarkdiquark schemes. In this contribution, we discuss the possible assignment of the recently discovered Ωc(3327)0, Ξb(6327)0, and Ξb(6333)0 as D-wave excited states in the charm and bottom sectors, respectively. Additionally, we discuss why the presence or absence of the ρ-mode excitations in the experimental spectrum is the key to distinguishing between the quark-diquark and three-quark behaviors.

Singly charm baryons with higher-order 𝒪1m2 corrections in hCQM: Revisited

In this study, singly charm baryons [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] have been studied. The known hypercentral Constituent Quark Model (hCQM) has been subjected to an addition of second-order correction term to the mass in spin-dependent term. This has allowed to observe the expected spin-splitting in the correct order and modify the previous findings to a new level. All the other properties have been obtained ranging from magnetic moment to strong decay width along with the linearly observed Regge trajectories.

The strong decay of higher vector Upsilon(11020) state in the framework of non-relativistic quark model

An analytical study of a source of Beauty mesons (B mesons) by the Strong decay of Upsilon(11020) is performed to obtain various modes of B mesons. The non-relativistic quark model framework is used to predict the masses of the bottomonium mesons. The strong decay of the Upsilon(11020) state is calculated utilizing Quark Pair Creation model. In addition, the branching ratio of the strong decay has been calculated for each decay width and using them to estimate the number of B-meson pairs for each strong decay width. The results show reasonable agreement with recent Particle Data Group data, in particular with the total strong decay width of Upsilon(11020). The Upsilon(11020) particle is expected to be a good candidate for the conventional Upsilon(6S) state and provides both types of strange and non-strange B mesons. We found new conclusions for the strong decay widths of the Upsilon(11020) in the relativistic phase space. The strong width of the B^{*}B^{*} channel is predicted to be the highest width by the ratio (cong 51%) concerning higher vector Upsilon(11020) State. In addition, the specific B_{s}B_{s}^{*} channel is expected to be the highest width relative to higher Upsilon resonances.

Strong decays of singly heavy baryons from a chiral effective theory of diquarks

A chiral effective theory of scalar and vector diquarks is formulated, which is based on $SU(3)_R\times SU(3)_L$ chiral symmetry and includes interactions between scalar and vector diquarks with one or two mesons. We find that the diquark interaction term with two mesons breaks the $U(1)_A$ and flavor $SU(3)$ symmetries. To determine the coupling constants of the interaction Lagrangians, we investigate one-pion emission decays of singly heavy baryons $Qqq$ ($Q=c, b$ and $q=u,d,s$), where baryons are regarded as diquark--heavy-quark two-body systems. Using this model, we present predictions of the unobserved decay widths of singly heavy baryons. We also study the change of masses and strong decay widths of singly heavy baryons under partial restoration of chiral symmetry.

Strong decay widths and mass spectra of charmed baryons

The total decay widths of the charmed baryons are calculated by means of the $^{3}{P}_{0}$ model. Our calculations consider in the final states: the charmed baryon-(vector/pseudoscalar) meson pairs and the (octet/decuplet) baryon-(pseudoscalar/vector) charmed meson pairs, within a constituent quark model. Furthermore, we calculate the masses of the charmed baryon ground states and their excitations up to the $D$-wave in a constituent quark model both in the three-quark and in the quark-diquark schemes, utilizing a Hamiltonian model based on a harmonic oscillator potential plus a mass splitting term that encodes the spin, spin-orbit, isospin, and flavor interactions. The parameters of the Hamiltonian model are fitted to the experimental data of the charmed baryon masses and decay widths. As the experimental uncertainties of the data affect the fitted model parameters, we have thoroughly propagated these uncertainties into our predicted charmed baryon masses and decay widths via a Monte Carlo bootstrap approach, which is often absent in other theoretical studies on this subject. Our quantum number assignments and predictions of the masses and strong partial decay widths are in reasonable agreement with the available data. Thus, our results show the ability to guide future measurements in LHCb, Belle and Belle II experiments. Finally, the appendices provide some details of our calculations, in which we include the flavor coupling coefficients, which are useful for further theoretical investigations.

The chiral Lagrangian with three flavors and large-N_c sum rules

We reconsider the chiral Lagrangian with three-flavor baryon fields. A systematic analysis of all low-energy constants (LEC) that contribute to the axial-vector and pseudoscalar currents in the baryon octet and decuplet fields at next-to-leading order in the inverse number of colors (1/N_c) of QCD is performed. We study the correlation function consisting of axial-vector and scalar currents as well. While there are 4 LEC relevant at leading chiral order, the number of relevant LEC at subleading order is 23. For those a leading order large-N_c analysis predicts 3 and 18 sum rules respectively. At the next accuracy level the number of sum rules is reduced to 2 and 8. Our results are illustrated by a tree-level analysis of available axial-vector coupling constants and strong decay widths of the baryon decuplet states.

The solution to the ‘1/2 vs 3/2’ puzzle

Using an almost complete relativistic method based on the Bethe–Salpeter equation, we study the mixing angle theta , the mass splitting bigtriangleup M, the strong decay widths Gamma (D^{({prime })}_1) and the weak production rates Br(Brightarrow D^{({prime })}_1ell nu _{ell }) of the D_1(2420) and D_1^{prime }(2430). We find there is the strong cancellation between the ^1P_1 and ^3P_1 partial waves in D_1^{prime }(2430) with theta sim -,35.3^{circ }, which leads to the ‘1/2 vs 3/2’ puzzle. The puzzle can not be overcome by adding only relativistic corrections since in a large parameter range where bigtriangleup M is linear varying and not small, the theta , Gamma (D^{({prime })}_1) and Br(Brightarrow D^{({prime })}_1ell nu _{ell }) remain almost unchanged but conflict with data. While in a special range around the mass inverse point where bigtriangleup M=0 and theta =pm , 90^{circ }, they change rapidly but we find the windows where bigtriangleup M, Gamma (D^{({prime })}_1) and Br(Brightarrow D^{({prime })}_1ell nu _{ell }) are all consistent with data. The small bigtriangleup M confirmed by experiment, is crucial to solve the ‘1/2 vs 3/2’ puzzle.

Two-body strong decays of the 2P and 3P charmonium states

Two-body open charm strong decays of the $2P$ and $3P$ charmonium states are studied by the Bethe-Salpeter(BS) method combined with the $^3P_0$ model. The wave functions and mass spectra of the $2P$ and $3P$ charmonium states are obtained by solving the BS equation with the relativistic correction. The strong decay widths and relative ratios of the $2P$ and $3P$ charmonium states are calculated. Comparing our results with the experimental data, we obtain some interesting results. Considering the $X^*(3860)$ as the $\chi_{c0}(2P)$, the total strong decay width is smaller than the experimental data. But the strong decay width depends on the parameter $\gamma$ in the $^3P_0$ model, and the mass and width of the $X^*(3860)$ have large errors, we cannot rule out the possibility that the $X^*(3860)$ is the $\chi_{c0}(2P)$. The $X(4160)$ is a good candidate for the $\chi_{c0}(3P)$, not only the strong decay width of the $\chi_{c0}(3P)$ is same as the experimental data, but the relative ratios $\frac{\Gamma(\chi_{c0}(3P)\to D\bar D)}{\Gamma(\chi_{c0}(3P)\to D^*\bar D^*)}\approx0.0019<0.09$, and $\frac{\Gamma({\chi_{c0}(3P)\to D\bar D^*})}{\Gamma({\chi_{c0}(3P)\to D^*\bar D^*})}=0<0.22$ are consistent with the experimental results of the $X(4160)$. Taking the $X(4274)$ as the $\chi_{c1}(3P)$, the strong decay width is consistent with the experimental data, so the $X(4274)$ is a good candidate for the $\chi_{c1}(3P)$. Assigning the $X(4350)$ as the $\chi_{c2}(3P)$, the corresponding strong decay width is slightly larger than the experimental data. To identify if the $X(4350)$ is $\chi_{c2}(3P)$, many more investigations are needed. All of the strong decay widths and relative ratios of the $2P$ and $3P$ charmonium states can provide the useful information to discover and confirm these particles in the future.

Bottomoniumlike tetraquarks in a chiral quark model

The low-lying bottomonium-like tetraquarks $b\bar{b}q\bar{q}$ $(q=u,\,d,\,s)$ with spin-parity $J^P=0^+$, $1^+$ and $2^+$, and isospin $I=0,\,1$ or $\frac{1}{2}$, are systematically investigated within the theoretical framework of real- and complex-scaling range of a chiral quark model, which has already been successfully applied in analysis of several multiquark systems. A complete four-body $S$-wave function, which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color configurations are considered. In the $b\bar{b}q\bar{q}$ $(q=u,\,d)$ tetraquark system, we found resonance states of $B^{(*)} \bar{B}^{(*)}$, $\Upsilon\omega$, $\Upsilon\rho$ and $\eta_b \rho$ nature with all possible $I(J^P)$ quantum numbers. Their masses are generally located in the energy range $11.0-11.3$ GeV and their widths are less than $10$ MeV. In addition, extremely narrow resonances, with two-meson strong decay widths less than $1.5$ MeV, are obtained in both $b\bar{b}u\bar{s}$ and $b\bar{b}s\bar{s}$ tetraquark systems. Particularly, four radial excitations of $\Upsilon K^*$ and $\eta_b K^*$ are found at $\sim11.1$ GeV in $J^P=0^+$, $1^+$ and $2^+$ channels of $b\bar{b}u\bar{s}$ system. One $\Upsilon(1S)\phi(2S)$ resonance state is obtained at $11.28$ GeV in the $J^P=1^+$ sector.

Strong decays of multistrangeness baryon resonances in the quark model

Decay properties of multistrangeness $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ resonances are computed and tested for internal quark configurations to pin down their spin-parity (${J}^{P}$) quantum numbers and internal structures. We found that the Roper-like resonances in the multistrangeness sector have large decay widths bearing resemblances to their siblings in light and heavy baryon sectors. In addition, we obtained the decay ratio for the $\mathrm{\ensuremath{\Omega}}(2012)$ as $\mathrm{\ensuremath{\Gamma}}(\mathrm{\ensuremath{\Omega}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\overline{K}\ensuremath{\pi})/\mathrm{\ensuremath{\Gamma}}(\mathrm{\ensuremath{\Omega}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\overline{K})=4.5%$, which is consistent with the experimental data when ${J}^{P}=3/{2}^{\ensuremath{-}}$ is assigned. This observation holds the possibility that the $\mathrm{\ensuremath{\Omega}}(2012)$ could naturally be explained as a three-quark state in the quark model. The decays of other low-lying $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ resonances are systematically analyzed, which would be useful to unveil the structure of these resonances in future experiments.

Mass spectra and decay properties of singly heavy bottom-strange baryons

In this paper, we enumerated ground and excited state masses of singly heavy bottom-strange baryons using the hypercentral constituent quark model (hCQM). The screening potential is used with color-Coulomb potential, as the confining potential. We determine the possible [Formula: see text] values to recently observed excited states like, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and four [Formula: see text] states. The Regge trajectories are plotted in [Formula: see text] plane to assign the [Formula: see text] values and quantum numbers to recently observed states. Using the calculated spectroscopic data, properties such as magnetic moment, transition magnetic moment, radiative decay width, and strong decay width are also investigated for all singly heavy bottom-strange baryonic system.

Heavy-quark mesons in the diabatic approach: string breaking and the quarkoniumlike spectrum

The Born-Oppenheimer approximation provides a description of heavy-quark mesons firmly based on lattice QCD, but its validity is limited to the lightest states lying far below the first open-flavour meson-meson threshold. This limitation can be overcome in the diabatic framework, a formalism first introduced in molecular physics, where the dynamics is encoded in a potential matrix whose elements can be derived from unquenched lattice QCD studies of string breaking. The off-diagonal elements of the potential matrix provide interaction between heavy quark-antiquark and meson-meson pairs, from which the mixing of quarkonium states with molecular components and the OZI-allowed strong decay widths are directly calculated. This allows for a QCD-based unified description of conventional quarkonium and unconventional mesons containing quark-antiquark and meson-meson components, what has proved to be successful for charmoniumlike and bottomoniumlike resonances.

Revisit the isospin violating decays of X(3872)

In this work, we revisit the isospin violating decays of $X(3872)$ in a coupled-channel effective field theory. In the molecular scheme, the $X(3872)$ is interpreted as the bound state of ${\overline{D}}^{*0}{D}^{0}/{\overline{D}}^{0}{D}^{*0}$ and ${D}^{*\ensuremath{-}}{D}^{+}/{D}^{\ensuremath{-}}{D}^{*+}$ channels. In a cutoff-independent formalism, we relate the coupling constants of $X(3872)$ with the two channels to the molecular wave function. The isospin violating decays of $X(3872)$ are obtained by two equivalent approaches, which amend some deficiencies about this issue in literature. In the quantum field theory approach, the isospin violating decays arise from the coupling constants of $X(3872)$ to two dimeson channels. In the quantum mechanics approach, the isospin violating is attributed to wave functions at the origin. We illustrate that how to cure the insufficient results in literature. Within the comprehensive analysis, we bridge the isospin violating decays of $X(3872)$ to its inner structure. Our results show that the proportion of the neutral channel in $X(3872)$ is over 80%. As a by-product, we calculate the strong decay width of $X(3872)\ensuremath{\rightarrow}{\overline{D}}^{0}{D}^{0}{\ensuremath{\pi}}^{0}$ and radiative one $X(3872)\ensuremath{\rightarrow}{\overline{D}}^{0}{D}^{0}\ensuremath{\gamma}$. The strong decay width and radiative decay width are about 30 keV and 10 keV, respectively, for the binding energy from $\ensuremath{-}300\text{ }\text{ }\mathrm{keV}$ to $\ensuremath{-}50\text{ }\text{ }\mathrm{keV}$.

Strong and electromagnetic decays of the radially excited D_s and B_s mesons in light cone QCD sum rules

Recently, LHCb Collaboration announced the discovery of radial excitations of D_s and B_s mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited D_s(2S) and B_s(2S) mesons within the light cone QCD sum rules method.

Exotic resonances of fully-heavy tetraquarks in a lattice-QCD insipired quark model

Fully-heavy tetraquark states, i.e. $cc\bar{c}\bar{c}$, $bb\bar{b}\bar{b}$, $bb\bar{c}\bar{c}$ ($cc\bar{b}\bar{b}$), $cb\bar{c}\bar{c}$, $cb\bar{b}\bar{b}$, and $cb\bar{c}\bar{b}$, are systematically investigated by means of a non-relativistic quark model based on lattice-QCD studies of the two-body $Q\bar{Q}$ interaction, which exhibits a spin-independent Cornell potential along with a spin-spin term. The four-body problem is solved using the Gaussian expansion method; additionally, the so-called complex scaling technique is employed so that bound, resonance, and scattering states can be treated on the same footing. Moreover, a complete set of four-body configurations, including meson-meson, diquark-antidiquark, and K-type configurations, as well as their couplings, are considered for spin-parity quantum numbers $J^{P(C)}=0^{+(+)}$, $1^{+(\pm)}$, and $2^{+(+)}$ in the $S$-wave channel. Several narrow resonances, with two-meson strong decay widths less than 30 MeV, are found in all of the tetraquark systems studied. Particularly, the fully-charm resonances recently reported by the LHCb Collaboration, at the energy range between 6.2 and 7.2 GeV in the di-$J/\psi$ invariant spectrum, can be well identified in our calculation. Focusing on the fully-bottom tetraquark spectrum, resonances with masses between 18.9 and 19.6 GeV are found. For the remaining charm-bottom cases, the masses are obtained within a energy region from 9.8 GeV to 16.4 GeV. All these predicted resonances can be further examined in future experiments.

Quark Structure of the X (4500), X (4700) and χc(4P,5P) States

We study some of the main properties (masses and open-flavor strong decay widths) of 4P and 5P charmonia. While there are two candidates for the χc0(4P,5P) states, the X(4500) and X(4700), the properties of the other members of the χc(4P,5P) multiplets are still completely unknown. With this in mind, we start to explore the charmonium interpretation for these mesons. Our second goal is to investigate if the apparent mismatch between the Quark Model (QM) predictions for χc0(4P,5P) states and the properties of the X(4500) and X(4700) mesons can be overcome by introducing threshold corrections in the QM formalism. According to our coupled-channel model results for the threshold mass shifts, the χc0(5P)→X(4700) assignment is unacceptable, while the χc0(4P)→X(4500) or X(4700) assignments cannot be completely ruled out.