<p>We present a detailed study of the partial decay widths of a spin-parity resonance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>N</mi><mo>*</mo></msup></math> with a mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>≃</mo><mn>2070</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math> obtained from the coupled channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-wave vector-baryon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ω</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>*</mo></msup><mi mathvariant="normal">Λ</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>*</mo></msup><mi mathvariant="normal">Σ</mi></math> dynamics. This state, which couples strongly to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>*</mo></msup><mi mathvariant="normal">Σ</mi></math> channel, corresponds to a nucleon with a hidden strange quark content, in analogy to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mi>c</mi></msub></math> states discovered by the LHCb Collaboration, and we denote it as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mi>s</mi></msub><mo stretchy="false">(</mo><mn>2080</mn><mo stretchy="false">)</mo></math>. A state with such a nature can decay to vector-baryon, pseudoscalar-baryon, and pseudoscalar-baryon resonance channels, involving triangular loops in the latter two cases. As we will show, the partial decay widths to pseudoscalar-baryon resonance channels, like <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi><msup><mi>N</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>1535</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi><msup><mi>N</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>1650</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi mathvariant="normal">Λ</mi><mo stretchy="false">(</mo><mn>1405</mn><mo stretchy="false">)</mo></math>, are comparable to those related to ground state baryons in the final state, like <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi mathvariant="normal">Λ</mi></math>. In this way, reactions involving such lighter baryon resonances in the final state can be used as an alternative source of information on the properties of an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>N</mi><mo>*</mo></msup></math> with hidden strangeness.</p>

Brazil

Breno Agatão

A. Vertel Nieto

K.P. Khemchandani

A. Martínez Torres

South Korea

Seung-il Nam

Bolstering up the existence of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mi>s</mi></msub><mo stretchy="false">(</mo><mn>2080</mn><mo stretchy="false">)</mo></math>

<p>In view of the renewing experimental interest for searching strangeness <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>+</mo><mn>1</mn></math> baryons at J-PARC, we study the existence of light baryon resonances with strangeness <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo>+</mo><mn>1</mn></mrow></math> generated in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>K</mi><mo>−</mo><mo stretchy="false">(</mo><msup><mrow><mi>N</mi></mrow><mrow><mo>*</mo></mrow></msup><mo>/</mo><msup><mrow><mi mathvariant="normal">Δ</mi></mrow><mrow><mo>*</mo></mrow></msup><mo stretchy="false">)</mo></mrow></math> system, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>N</mi><mo>*</mo></msup></math> represents either <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>N</mi></mrow><mrow><mo>*</mo></mrow></msup><mo stretchy="false">(</mo><mn>1535</mn><mo stretchy="false">)</mo><mo>/</mo><msup><mrow><mi>N</mi></mrow><mrow><mo>*</mo></mrow></msup><mo stretchy="false">(</mo><mn>1650</mn><mo stretchy="false">)</mo><mo>/</mo><msup><mrow><mi>N</mi></mrow><mrow><mo>*</mo></mrow></msup><mo stretchy="false">(</mo><mn>1700</mn><mo stretchy="false">)</mo></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">Δ</mi><mo>*</mo></msup></math> corresponds to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mo stretchy="false">(</mo><mn>1620</mn><mo stretchy="false">)</mo></math>. The description of the properties of the aforementioned states requires considering the dynamics involved in the coupled pseudoscalar-baryon (PB) and vector-baryon (VB) systems with strangeness <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mo>=</mo><mn>0</mn></math> in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> wave. For the purpose of our current study, we consider the PB and VB channels to which the mentioned <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>N</mi><mo>*</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">Δ</mi><mo>*</mo></msup></math> resonances couple and solve the Faddeev equations for the coupled channel system <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math>-PB, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math>-VB, with all interactions being in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> wave. Despite some strong attraction present in two of the subsystems, we do not find clear evidence supporting the formation of strangeness <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo>+</mo><mn>1</mn></mrow></math> states, with spin-parity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>+</mo></msup></math>, in the energy region 2000–2200 MeV. However, the case of spin-parity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mn>2</mn><mo>+</mo></msup></math> seems more promising, showing the formation of a resonance with a mass around 2167 MeV, with a width of 90–100 MeV. We suggest that a signal of such a state could be found in processes with final states like <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi>N</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>892</mn><mo stretchy="false">)</mo><mi>N</mi></math>.</p>

Brenda B. Malabarba

Strangeness <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">+</mo><mn>1</mn></mrow></math> light multiquark baryons

The femtoscopic ϕN correlation function is studied within a hadronic effective Lagrangian approach with coupled channels, based on hidden local symmetry. The results are compared with the data recently reported by the ALICE collaboration. We find that the correlation function has very different features for the ϕN system in the spin 1/2 and 3/2 configurations, with the spin-averaged combination matching well with the experimental data. A strong attraction, leading to the formation of a ϕN bound state or a very prominent cusp is found in the spin 3/2 case. The correlation function for spin 1/2, on the other hand, is strongly impacted by the negative parity <math><msup><mrow><mi>N</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>(</mo><mn>1895</mn><mo>)</mo></math> nucleon resonance.

Luciano M. Abreu

Japan

Philipp Gubler

Atsushi Hosaka

A study of the Correlation Function

We study hyperon resonances by solving coupled channel scattering equations. The coupled systems include pseudoscalar- and vector-baryon channels. The parameters of the model are restricted by making a <math><msup><mi>χ</mi><mn>2</mn></msup></math>-fit to the cross-section data on processes: <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi></mrow></math>, <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>n</mi></mrow></math>, <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>η</mi><mi>Λ</mi></mrow></math>, <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msup><mi>π</mi><mn>0</mn></msup><mi>Λ</mi></mrow></math>, <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>Σ</mi><mn>0</mn></msup></mrow></math>, <math><mrow><msup><mi>K</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><msup><mi>π</mi><mo>±</mo></msup><msup><mi>Σ</mi><mo>∓</mo></msup></mrow></math>. Data on the energy-level shift and width of the <math><mrow><mn>1</mn><mi>s</mi></mrow></math> state of the kaonic hydrogen, as well as some cross-section ratios near the threshold are also considered in the fit. Two types of fit are found as a result. In both cases, the properties of <math><mrow><mi>Λ</mi><mo>(</mo><mn>1405</mn><mo>)</mo></mrow></math> are well reproduced. In addition to this, a <math><mi>Σ</mi></math> state is also found with mass around 1400 MeV. Cross sections, obtained with one of the two fits, are found to stay close to the data at energies away from the thresholds too, and as a result resonances with higher masses have also been studied.

Spain

J.A. Oller

Hyperon resonances coupled to pseudoscalar- and vector-baryon channels

Inspired by the recent discovery of the pentaquark states <math><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>(</mo><mn>4450</mn><mo>)</mo></math> and <math><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>(</mo><mn>4380</mn><mo>)</mo></math>, which can be viewed as excited nucleon states with hidden charm, we study the three-body interaction of a kaon and a pair of <math><mi>D</mi><msup><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mo>⁎</mo></mrow></msup></math> in isospin 0 and 1. We show that the two body interactions stringently constrained by the existence of the <math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi><mn>0</mn></mrow><mrow><mo>⁎</mo></mrow></msubsup><mo>(</mo><mn>2317</mn><mo>)</mo></math>, <math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi><mn>1</mn></mrow><mrow><mo>⁎</mo></mrow></msubsup><mo>(</mo><mn>2460</mn><mo>)</mo></math>, <math><mi>X</mi><mo>(</mo><mn>3872</mn><mo>)</mo></math>, and <math><msub><mrow><mi>Z</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>(</mo><mn>3900</mn><mo>)</mo></math>, which are widely believed to contain large DK, <math><msup><mrow><mi>D</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mi>K</mi></math>, and <math><mi>D</mi><msup><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mo>⁎</mo></mrow></msup></math> components, inevitably lead to the existence of a heavy <math><msup><mrow><mi>K</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math> meson with hidden charm. Concrete coupled channel three-body calculations yield its mass and width as <math><mo>(</mo><mn>4307</mn><mo>±</mo><mn>2</mn><mo>)</mo><mo>−</mo><mi>i</mi><mo>(</mo><mn>9</mn><mo>±</mo><mn>2</mn><mo>)</mo><mspace width="0.25em"></mspace><mtext>MeV</mtext></math> with <math><mi>I</mi><mo>(</mo><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo>)</mo><mo>=</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>(</mo><msup><mrow><mn>1</mn></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></math>. This state, if found experimentally, definitely cannot be accommodated in a <math><mi>q</mi><mover><mrow><mi>q</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> picture, and therefore presents a clear case of an exotic hadron.

Germany

Xiu-Lei Ren

China

Li-Sheng Geng

Mesons With Hidden Charm Arising From (3872) and (3900) Dynamics

In heavy-ion collisions, after the quark-gluon plasma there is a hadronic gas phase. Using effective Lagrangians, we study the interactions of charmed mesons which lead to <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> production and absorption in this gas. We update and extend previous calculations introducing strange meson interactions and also including the interactions mediated by the recently measured exotic charmonium resonances <math><mrow><mi>Z</mi><mo>(</mo><mn>3900</mn><mo>)</mo></mrow></math> and <math><mrow><mi>Z</mi><mo>(</mo><mn>4025</mn><mo>)</mo></mrow></math>. These resonances open new reaction channels for the <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math>, which could potentially lead to changes in its multiplicity. We compute the <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> production cross section in processes such as <math><mrow><msubsup><mi>D</mi><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><mo>+</mo><msup><mover><mi>D</mi><mo>¯</mo></mover><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mrow><mo>(</mo><mi>π</mi><mo>,</mo><mi>ρ</mi><mo>,</mo><mi>K</mi><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup><mo>)</mo></mrow></mrow></math> and also the <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> absorption cross section in the corresponding inverse processes. Using the obtained cross sections as input to solve the appropriate rate equation, we conclude that the interactions in the hadron gas phase lead to a 20–24% reduction of the <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> abundance. Within the uncertainties of the calculation, this reduction is the same at the Relativistic Heavy Ion Collider and the large Hadron Collider.

L.M. Abreu

F.S. Navarra

M. Nielsen

Update on <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> regeneration in a hadron gas

We calculate the time evolution of the X(3872) abundance in the hot hadron gas produced in the late stage of heavy ion collisions. We use effective field Lagrangians to obtain the production and dissociation cross sections of X(3872) . In this evaluation we include diagrams involving the anomalous couplings πD⁎D¯⁎ and XD¯⁎D⁎ and also the couplings of the X(3872) with charged D and D⁎ mesons. With these new terms the X(3872) interaction cross sections are much larger than those found in previous works. Using these cross sections as input in rate equations, we conclude that during the expansion and cooling of the hadronic gas, the number of X(3872) , originally produced at the end of the mixed QGP/hadron gas phase, is reduced by a factor of 4.

X (3872) production and absorption in a hot hadron gas

To understand the nature of the X(5568) , recently observed in the mass spectrum of the Bs0ÏÂ± system by the D0 Collaboration, we have investigated, in a previous work, a scalar tetraquark (diquakâantidiquark) structure for it, within the two-point QCD sum rules method. We found that it is possible to obtain a stable value of the mass compatible with the D0 result, although a rigorous QCD sum rule constrained analysis led to a higher value of mass. As a continuation of our investigation, we calculate the width of the tetraquark state with same quark content as X(5568) , to the channel Bs0ÏÂ± , using the three-point QCD sum rule. We obtain a value of (20.4Â±8.7)Â MeV for the mass â¼ 5568 MeV, which is compatible with the experimental value of 21.9Â±6.4(sta)â2.5+5.0(syst)Â MeV/c2 . We find that the decay width to Bs0ÏÂ± does not alter much for a higher mass state.

J.M. Dias

C.M. Zanetti

A QCD sum rule calculation of the X±(5568)→Bs0π± decay width

In this paper, we review results from studies with unconventional many-hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally, systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases, one has experimental counterparts for the states found, while in some other cases, they remain as predictions, which we suggest to be searched in \break BESIII, Belle, LHCb, FAIR and other facilities.