A coupled channel analysis of the D⁎+D0 and D⁎0D+ system is performed to study the doubly charmed Tcc+ state recently discovered by the LHCb collaboration. We use a simple model for the scattering ...amplitude and production mechanism that allows us to describe well the experimental spectrum, and obtain the Tcc+ pole in the coupled channel T-matrix. We find that this bound state has a large molecular component. The isospin (I=0 or I=1) of the state cannot be inferred from the D0D0π+ spectrum alone, although there is some experimental evidence that points to the I=0 interpretation. Therefore, we use the same formalism to predict other DDπ spectra. In the case the Tcc+ has I=1, we also predict the location of the other two members (Tcc++ and Tcc0) of the triplet. Finally, using Heavy-Quark Spin Symmetry, we predict the location of possible heavier D⁎D⁎ (I=0 or I=1) partners.
We discuss a model-independent estimator of the likelihood of the compositeness of a shallow S-wave bound or virtual state. The approach is based on an extension of Weinberg’s relations in Weinberg ...(Phys Rev 137:B672, 1965) and it relies only on the proximity of the energy of the state to the two-hadron threshold to which it significantly couples. The scheme only makes use of the experimental scattering length and the effective range low energy parameters, and it is shown to be fully consistent for predominantly molecular hadrons. As explicit applications, we analyse the case of the deuteron, the
1
S
0
nucleon-nucleon virtual state and the exotic
D
s
0
∗
(
2317
)
±
, and find strong support to the molecular interpretation in all cases. Results are less conclusive for the
D
s
0
∗
(
2317
)
±
, since the binding energy of this state would be significantly higher than that of the deuteron, and the approach employed here is at the limit of its applicability. We also qualitatively address the case of the recently discovered
T
cc
+
state, within the isospin limit to avoid the complexity of the very close thresholds
D
0
D
∗
+
and
D
+
D
∗
0
, which could mask the ingredients of the approach proposed in this work.
Mapping states with explicit gluonic degrees of freedom in the light sector is a challenge, and has led to controversies in the past. In particular, the experiments have reported two different hybrid ...candidates with spin-exotic signature, π_{1}(1400) and π_{1}(1600), which couple separately to ηπ and η^{'}π. This picture is not compatible with recent Lattice QCD estimates for hybrid states, nor with most phenomenological models. We consider the recent partial wave analysis of the η^{(')}π system by the COMPASS Collaboration. We fit the extracted intensities and phases with a coupled-channel amplitude that enforces the unitarity and analyticity of the S matrix. We provide a robust extraction of a single exotic π_{1} resonant pole, with mass and width 1564±24±86 and 492±54±102 MeV, which couples to both η^{(')}π channels. We find no evidence for a second exotic state. We also provide the resonance parameters of the a_{2}(1320) and a_{2}^{'}(1700).
We study the nature of the new signal reported by LHCb in the J/ψp spectrum. Based on the S-matrix principles, we perform a minimum-bias analysis of the underlying reaction amplitude, focusing on the ...analytic properties that can be related to the microscopic origin of the Pc(4312)+ peak. By exploring several amplitude parametrizations, we find evidence for the attractive effect of the Σc+D¯0 channel, which is not strong enough, however, to form a bound state.
We analyze the modifications that a dense nuclear medium induces in the Ds0⁎(2317)± and Ds1(2460)±. In the vacuum, we consider them as isoscalar D(⁎)K and ▪S-wave bound states, which are dynamically ...generated from effective interactions that lead to different Weinberg compositeness scenarios. Matter effects are incorporated through the two-meson loop functions, taking into account the self energies that the D(⁎), ▪, K, and ▪ develop when embedded in a nuclear medium. Although particle-antiparticle Ds0,s1(⁎)(2317,2460)+versusDs0,s1(⁎)(2317,2460)− lineshapes are the same in vacuum, we find extremely different density patterns in matter. This charge-conjugation asymmetry mainly stems from the very different kaon and antikaon interaction with the nucleons of the dense medium. We show that the in-medium lineshapes found for these resonances strongly depend on their D(⁎)K/▪ molecular content, and discuss how this novel feature can be used to better determine/constrain the inner structure of these exotic states.
We perform a coupled channel study of the meson-meson S waves with isospin (I) 0 and 1/2 up to 2 GeV. A new approach is derived that allows one to include the many channels pipi, KKover , etaeta, ...sigmasigma, etaeta; eta; eta; , rhorho, omegaomega, omegavarphi, varphivarphi, a(1)pi, and pipi with still few free parameters. It follows that coupled channel dynamics is strong and cannot be neglected in order to study resonance properties in the region 1.4-1.6 GeV. All the resonances with masses below 2 GeV and I=0 and 1/2 are generated. We identify the f(0)(1710) and an important contribution to the f (0)(1500) as an unmixed glueball. This is based on an accurate agreement of our results with predictions of lattice QCD and the chiral suppression of the coupling of a scalar glueball to qover q. Another pole, mainly corresponding to the f_{0}(1370), is a pure octet state.
We have conducted a study of the femtoscopic correlation functions for the D0D⁎+ and D+D⁎0 channels that build the Tcc state. We develop a formalism that allows us to factorize the scattering ...amplitudes outside the integrals in the formulas, and the integrals involve the range of the strong interaction explicitly. For a source of size of 1 fm, we find values for the correlation functions of the D0D⁎+ and D+D⁎0 channels at the origin around 30 and 2.5, respectively, and we see these observables converging to unity already for relative momenta of the order of 200 MeV. We conduct tests to see the relevance of the different contributions to the correlation function and find that it mostly provides information on the scattering length, but should the correlation functions be measured with the precision of the latest experiments, the effective range of the D0D⁎+ could also be obtained.
The next generation of electron-hadron facilities has the potential for significantly improving our understanding of exotic hadrons. The XYZ states have not been seen in photon-induced reactions so ...far. Their observation in such processes would provide an independent confirmation of their existence and offer new insights into their internal structure. Based on the known experimental data and the well-established quarkonium and Regge phenomenology, we give estimates for the exclusive cross sections of several XYZ states. For energies near threshold we expect cross sections of few nanobarns for the Zc(3900) + and upwards of tens of nanobarns for the X(3872), which are well within reach of new facilities.
We perform a systematic analysis of the
J
/
ψ
→
γ
π
0
π
0
and
→
γ
K
S
0
K
S
0
partial waves measured by BESIII. We use a large set of amplitude parametrizations to reduce the model bias. We determine ...the physical properties of seven scalar and tensor resonances in the 1–
2.5
GeV
mass range. These include the well known
f
0
(
1500
)
and
f
0
(
1710
)
, that are considered to be the primary glueball candidates. The hierarchy of resonance couplings determined from this analysis favors the latter as the one with the largest glueball component.
We study the nature of the new signal reported by LHCb in the $J/Ψp$ spectrum. Based on the S-matrix principles, we perform a minimum-bias analysis of the underlying reaction amplitude, focusing on ...the analytic properties that can be related to the microscopic origin of the $P_c$(4312)+ peak. By exploring several amplitude parameterizations, we find evidence for the attractive effect of the $Σ^+_c$$\bar{D}^0$ channel, that is not strong enough, however, to form a bound state.
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