Coupled-channel Effects Research Articles

Lattice spectra of the DDK three-body system with Lorentz covariant kinematic

The DDK system has gained increasing attention in recent research due to its potential to contain a three-hadron bound state. This paper utilizes an extension of the nonrelativistic effective field theory and the finite volume particle-dimer framework to derive Lorentz invariant quantization conditions for the DDK three-body system. Using current model input conditions, the finite volume energy spectrum of the DDK three-body system was calculated. This new calculation incorporates relativistic kinematics, allowing it to be applicable across a broader energy range starting from the threshold. In this work, we present a comprehensive O(p2) calculation. The spurious pole is effectively subtracted within the framework of relativistic kinematics. The spectra in the moving frame are also obtained. These analyses provide a broader testing ground for future lattice simulations. Based on this framework, it is expected to reveal more detailed properties of the DDK system and other three-hadron systems, if various higher-order effects, such as the isospin I=1 DK interactions and the coupled-channel effects are introduced. Published by the American Physical Society 2024

Masses and radiative decay widths of Ds0*(2317) and Ds1′(2460) and their bottom analogs

We study the mass spectra and radiative decays of Ds0*(2317) and Ds1′(2460) in an unquenched framework. In addition to coupled channel effects between the cs¯ cores and D(*)K channels, D(*)K−D(*)K self-interactions are also considered in this work and we succeed to reproduce their mass spectra. Furthermore, we study the radiative decays of the Ds0*(2317) and Ds1′(2460) by simultaneously including the compound structures of conventional cs¯ cores and D(*)K components. We also calculate their bottom analogs with heavy quark symmetry. Our study offers useful insights into the important unquenched effects in the formation of Ds0*(2317), Ds1′(2460), and the bottom counterparts. Published by the American Physical Society 2024

Pole structure of Pψ N(4312)+ via machine learning and uniformized S-matrix

Abstract We probed the pole structure of the Pψ N(4312)+ using a trained deep neural network. The training dataset was generated using uniformized independent S-matrix poles to ensure that the resulting interpretation is as model-independent as possible. To prevent possible ambiguity in the interpretation of the pole structure, we included the contribution from the off-diagonal elements of the S-matrix. Our trained model favors a possible three-pole structure of Pψ N(4312)+ signal, with one pole on each of the unphysical sheets. The two poles on two different Riemann sheets can be associated with a pole-shadow pair which is a characteristic of a true resonance. On the other hand, the last isolated pole is most likely associated with the coupled-channel effect in the meson-baryon system. The combined effect of these poles produced a peak below the ΣcD threshold which mimics the line shape of a hadronic molecule.

Physical coherent cancellation of optical addressing crosstalk in a trapped-ion experiment

Abstract We present an experimental investigation of coherent crosstalk cancellation methods for light delivered to a linear ion chain cryogenic quantum register. The ions are individually addressed using focused laser beams oriented perpendicular to the crystal axis, which are created by imaging each output of a multi-core photonic-crystal fibre waveguide array onto a single ion. The measured nearest-neighbor native crosstalk intensity of this device for ions spaced by 5 µm is found to be ∼ 10 − 2 . We show that we can suppress this intensity crosstalk from waveguide channel coupling and optical diffraction effects by a factor > 10 3 using cancellation light supplied to neighboring channels which destructively interferes with the crosstalk. We measure a rotation error per gate on the order of ϵ x ∼ 10 − 5 on spectator qubits, demonstrating a suppression of crosstalk error by a factor of > 10 2 . We compare the performance to composite pulse methods for crosstalk cancellation, and describe the appropriate calibration methods and procedures to mitigate phase drifts between these different optical paths, including accounting for problems arising due to pulsing of optical modulators.

Investigation on the bottom analogs Tbb− of Tcc+

We investigate the doubly bottom state Tbb− composed of two bottom mesons with JP=1+. The potentials are obtained using the one-boson exchange model. With the heavy quark flavor symmetry, all the parameters in the model are determined by fitting the experimental data of doubly charmed state Tcc+ from our previous work. Our analysis indicates that the isospin symmetry is well preserved. We identify a deeply bound Tbb− state with quantum numbers I(JP)=0(1+), in contrast to the loosely bound Tcc+. Additionally, we discover a resonant Tbb− state with I(JP)=1(1+). Furthermore, our investigation into the B¯B¯*−B¯*B¯* coupled channel effect reveals its important impact. The binding energy of the bound I(JP)=0(1+) states becomes deeper, while the resonant Tbb− state with I(JP)=1(1+) remains nearly unchanged. Published by the American Physical Society 2024

Dynamical channel coupling in strong-field ionization of CO2.

We present a theoretical study employing the time-dependent density functional theory (TDDFT) to explore the effects of angle-resolved channel coupling in strong field ionization of carbon dioxide (CO2) molecules. Our results reveal significant angular sensitivity of both the channel-resolved ionization probabilities and the effects of laser-induced channel couplings. By applying a linearly polarized two-color field scheme, we demonstrate the ability to significantly modify the strength of the laser-induced coupling, evidenced by the changes in the population distributions among the ionic states induced by the strong-field ionization. Importantly, the two-color field optimally modulates the coupling strength at the alignment angle where ionization of the highest occupied molecular orbital (HOMO) electrons is most efficient. This optimization is attributed to the reduction of the electron shielding effect. Our research provides valuable insights into the coherent manipulation of electron distribution within the cation, paving the way for the precise control of ultrafast electron dynamics during strong-field ionization processes.

Exploring the mass spectrum and electromagnetic property of the ΞccK(*) and ΞccK¯(*) molecules

Using the one-boson-exchange model, we investigate the interactions between the doubly charmed baryon Ξcc(3621) and the S wave (anti-)kaon accounting for the S−D wave mixing and coupled-channel effects. We find the coupled ΞccK/ΞccK* state with I(JP)=0(1/2−), the ΞccK* state with 0(1/2−), the ΞccK¯ state with 0(1/2−), and the ΞccK¯* states with 0(1/2−,3/2−) can be recommended as good doubly charmed molecular candidates with strangeness |S|=1. We further examine their M1 radiative decay behaviors and magnetic moments within the constituent quark model framework. This information can enhance our understanding of their inner structures, including the distribution of electric charge and the orientation of the constituent quarks’ spins. Published by the American Physical Society 2024

Predicting possible molecular states of nucleons with Ξc , Ξc* , and Ξc′

In the framework of a one-boson-exchange model, we carry out a comprehensive investigation of the ΞcN/ΛcΣ/Ξc′N/ΣcΛ/Ξc*N/Σc*Λ/ΣcΣ/Σc*Σ interactions. We consider the S−D-wave mixing effects and the coupled-channel effects to derive the relevant effective potentials. Our results can predict several possible charm-strange deuteronlike Ξc(′,*)N hexaquarks, the Ξc′N molecules with I(IP)=0(0+), 0(1+), 1(1+), the Ξc*N molecules with 0(1+), 0(2+), 1(2+), and the coupled ΞcN/Ξc′N/Ξc*N/ΣcΣ/Σc*Σ molecule with 0(1+). We expect the experiments to search for our predictions of the Ξc(′,*)N bound states. Published by the American Physical Society 2024

Charmonia in an unquenched quark model

In this work, we study the charmonium spectrum within an unquenched quark model including coupled-channel effects. In couple-channel calculations, we include all of the opened charmed meson channels with the once-subtracted method, meanwhile we adopt a suppressed factor to soften the hard vertices given by the P03 model in the high momentum region. We obtain a good description of both the masses and widths for the well-established states in the charmonium spectrum. Furthermore, we give predictions for the higher S-, P-, and D-wave charmonium states up to mass region of ∼5.0 GeV. The magnitude of mass shifts due to the coupled-channel effects is estimated to be about 10s MeV. Although many decay channels are opened for the higher charmonium states, they are relatively narrow states. Their widths scatter in the range of ∼10s–100 MeV. Many charmoniumlike states, such as χc1(4274), χc0(3915), χc0(4500), χc0(4700), X(4160), X(4350), Y(4500), and ψ(4660)/Y(4710), can be accommodated by the charmonium spectrum when the unquenched coupled-channel effects are carefully considered. Published by the American Physical Society 2024

Beauty-charm meson family with coupled channel effects and their strong decays* *Supported by the National Natural Science Foundation of China (12322503, 12047503, 12075124), and the Natural Science Foundation of Jiangsu Province, China (BK20211267)

We systematically examined the mass spectra and their two-body hadronic decays of the beauty-charm meson family considering coupled channel effects. Our results can effectively explain the observed meson spectrum, and the prediction of the mass spectrum for unobserved beauty-charm mesons can be tested in future experiments. Compared with previous studies, we systematically examine the beauty-charm meson family within the coupled channel components. The state in beauty-charm meson family has few percent of coupled channel component, while the , , and states have more than ten percent of coupled channel component. The two-body hadronic decay widths of the state is as narrow as 3 MeV. The two-body hadronic decay widths of , , , , , and are approximately 109, 67, 60, 57, 201, and 76 MeV, respectively. Furthermore, the mixing effects between and states are discussed.

How does the X(3872) show up in e+e− collisions: Dip versus peak

We demonstrate that the dip observed near the total energy of 3872 MeV in the recent cross section data from the BESIII Collaboration for e+e−→J/ψπ+π− admits a natural explanation as a coupled-channel effect: it is a consequence of unitarity and a strong S-wave DD¯* attraction that generates the state X(3872). We anticipate the appearance of a similar dip in the e+e−→J/ψπ+π−π0 final state near the D*D¯* threshold driven by the same general mechanism, then to be interpreted as a signature of the predicted spin-2 partner of the X(3872). Published by the American Physical Society 2024

Unified unquenched quark model for heavy-light mesons with chiral dynamics

In this work, an unquenched quark model is proposed for describing the heavy-light mesons by taking into account the coupled-channel effects induced by chiral dynamics. After including a relativistic correction term for the strong transition amplitudes, both the mass spectra and decay widths of the observed heavy-light mesons can be successfully described simultaneously in a unified framework, several long-standing puzzles related to the small masses and broad widths are overcome naturally. We also provide valuable guidance in searching new heavy-light mesons by the detailed predictions of their masses, widths, and branching ratios. The success of the unquenched quark model presented in this work indicates it may be an important step for understanding the hadron spectrum. Published by the American Physical Society 2024

Quantum mechanical treatment of nuclear friction in coupled-channels heavy-ion fusion

Nuclear friction causes energy dissipation in heavy-ion collisions. Its understanding and inclusion in quantum mechanical reaction models are crucial for advancing the physics of heavy-ion reactions forming heavy elements. The effects of nuclear friction on heavy-ion fusion reactions are investigated using the coupled-channels density-matrix method. In this open-quantum-system description, a phenomenological nuclear friction form factor is introduced along with coherent coupled-channels effects. The key nucleus was the 92Zr target, due to its high density of low-lying non-collective excited states, which was recently theorised to be cause of nuclear friction. The calculations using the 16O + 92Zr collision showed that the inclusion of nuclear friction effects increased the fusion probability significantly, and that the agreement between the theoretical and experimental fusion barrier distributions was improved when nuclear friction effects were included.

Role of electromagnetic interactions in the X(3872) and its analogs

We investigate the role of the electromagnetic interaction in the formation and decay of the X(3872). The binding properties of the X(3872) are studied by assuming the molecular nature and considering the S−D wave mixing, isospin breaking, and coupled channel effects, and in particular the correction from the electromagnetic interaction. The radiative decays can better reflect the difference between the charged and neutral DD¯* components, since the electromagnetic interaction explicitly breaks the isospin symmetry. We further study the radiative decay widths with the obtained wave functions for different DD¯* channels. We also explore other similar hidden-charm molecular states. The electromagnetic interaction can make the molecule tighter. Our result of the radiative decay width for X(3872)→γJ/ψ is in agreement with the experiment. The branching ratio Rγψ is less than 1 in our framework, which supports the Belle and BESIII measurements. Published by the American Physical Society 2024

Coupled-channel description of charmed heavy hadronic molecules within the meson-exchange model and its implication

Motivated by the first observation of the double-charm tetraquark Tcc+(3875) by the LHCb Collaboration, we investigate the nature of Tcc+ as an isoscalar DD* hadronic molecule in a meson-exchange potential model incorporated by the coupled-channel effects and three-body unitarity. The D0D0π+ invariant mass spectrum can be well-described and the Tcc+ pole structure can be precisely extracted. Under the hypothesis that the interactions between the heavy flavor hadrons can be saturated by the light meson-exchange potentials, the near-threshold dynamics of Tcc+ can shed light on the binding of its heavy-quark spin symmetry (HQSS) partner D*D* (I=0) and on the nature of other heavy hadronic molecule candidates such as X(3872) and Zc(3900) in the charmed-anticharmed systems. The latter states can be related to Tcc+ in the meson-exchange potential model with limited assumptions based on the SU(3) flavor symmetry relations. The combined analysis, on the one hand, indicates the HQSS breaking effects among those HQSS partners, and on the other hand, highlights the role played by the short and long-distance dynamics for the near threshold D(*)D(*) and D(*)D¯(*)+c.c. systems. Published by the American Physical Society 2024

Compositeness of Tcc and X(3872) by considering decay and coupled-channels effects

The compositeness of weakly bound states is discussed using the effective field theory from the viewpoint of the low-energy universality. We introduce a model with coupling of the single-channel scattering to the bare state, and study the compositeness of the bound state by varying the bare state energy. In contrast to the naive expectation that the near-threshold states are dominated by the molecular structure, we demonstrate that a noncomposite state can always be realized even with a small binding energy. At the same time, however, it is shown that a fine tuning is necessary to obtain the noncomposite weakly bound state. In other words, the probability of finding a model with the composite dominant state becomes larger with the decrease of the binding energy, in accordance with the low-energy universality. For the application to exotic hadrons, we then discuss the modification of the compositeness due to decay and coupled-channels effects. We quantitatively show that these contributions suppress the compositeness, because of the increase of the fraction of other components. Finally, as examples of near-threshold exotic hadrons, the structures of Tcc and X(3872) are studied by evaluating the compositeness. We find the importance of the coupled-channels and decay contributions for the structures of Tcc and X(3872), respectively. Published by the American Physical Society 2024

Investigating the M1 radiative decay behaviors and the magnetic moments of the predicted triple-charm molecular-type pentaquarks

In this work, we systematically study the electromagnetic properties including the M1 radiative decay widths and the magnetic moments of the isoscalar ΞccD(*), ΞccD1, and ΞccD2* triple-charm molecular-type pentaquark candidates, where we adopt the constituent quark model and consider both the S−D wave mixing effect and the coupled channel effect. Our numerical results suggest that the M1 radiative decay widths and the magnetic moments of the isoscalar ΞccD(*), ΞccD1, and ΞccD2* triple-charm molecular-type pentaquark candidates can reflect their inner structures, and the study of the electromagnetic properties is an important step to construct the family of the triple-charm molecular-type pentaquarks. With the accumulation of the experimental data during the high-luminosity phase of LHC, we expect that the present work combined with the corresponding mass spectrum information can encourage the experimental colleagues at LHCb to focus on the isoscalar ΞccD(*), ΞccD1, and ΞccD2* triple-charm molecular-type pentaquark candidates. Published by the American Physical Society 2024

Predictions of the strange partner of Tcc in the quark delocalization color screening model

Inspired by the detection of Tcc tetraquark state by LHCb Collaboration, we perform a systemical investigation of the low-lying doubly heavy charm tetraquark states with strangeness in the quark delocalization color screening model in the present work. Two kinds of configurations, the meson-meson configuration and diquark-antidiquark configuration, are considered in the calculation. Our estimations indicate that the coupled channel effects play important role in the multiquark system, and a bound state with JP=1+ and a resonance state with JP=0+ have been predicted. The mass of the bound state is evaluated to be (3971–3975) MeV, while the mass and width of the resonance are determined to be (4113–4114) MeV and (14.3–16.1) MeV, respectively. Published by the American Physical Society 2024

Surveying the mass spectra and the electromagnetic properties of the Ξc(′,*)D(*) molecular pentaquarks

Motivated by the observed PψsΛ(4459)/PψsΛ(4338) and Tcc(3875)+ states as the ΞcD¯*/ΞcD¯ and DD* molecular candidates, respectively, in this work we investigate the Ξc(′,*)D(*) molecular systems. We obtain the mass spectra and the corresponding spatial wave functions of the Ξc(′,*)D(*)-type double-charm molecular pentaquark candidates with single strangeness, where we utilize the one-boson-exchange model and take into account both the S−D wave-mixing effect and the coupled-channel effect. Our results show that the most promising candidates of the double-charm molecular pentaquarks with single strangeness include the ΞcD state with I(JP)=0(1/2−), the Ξc′D state with I(JP)=0(1/2−), the ΞcD* states with I(JP)=0(1/2−,3/2−), the Ξc*D state with I(JP)=0(3/2−), the Ξc′D* states with I(JP)=0(1/2−,3/2−), and the Ξc*D* states with I(JP)=0(1/2−,3/2−,5/2−). To gain further insight into the inner structures and the properties of the isoscalar Ξc(′,*)D(*) molecular candidates, we utilize the constituent quark model to analyze their M1 radiative decay behaviors and magnetic moments based on the obtained mass spectra and spatial wave functions, which can offer significant information to determine their spin-parity quantum numbers and configurations in the forthcoming experiments. We suggest that our experimental colleagues search for the predicted Ξc(′,*)D(*) molecular states. Published by the American Physical Society 2024

Compositeness of near-threshold exotic hadrons with decay and coupled-channel effects

Abstract. The near-threshold exotic hadrons such as Tcc and X(3872) are naively considered as the hadronic molecular state from the viewpoint of the low-energy universality. However, it is also known that the elementary dominant state is not completely excluded as the internal structure of the near-threshold states. Furthermore, the dominance of molecules is expected to be modified by the decay or coupled channels. We discuss these features of the near-threshold bound states by calculating the compositeness with the effective field theory.