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J. Vijande

Publications and source records attributed to J. Vijande.

At least 19 recordsLinked to original sources
arXiv2025

Open-Flavor Heavy Hadron Production in Heavy-Ion Collisions

We study the production of open-flavor heavy hadrons in relativistic heavy-ion collisions. The hadronization in the quark-gluon plasma is described in the quark coalescence model. We evaluated yields and transverse momentum distributions. A simultaneous study of conventional and exotic hadrons is carried out. The Wigner functions are evaluated using hadron wave functions obtained from a single realistic quark model. Thus, results are presented in a single framework for the production of open-flavor heavy mesons, baryons, and exotic tetraquarks, in particular: $D^{0}$, $B^{0}$, $Λ_{Q}$, $Σ_{Q}$, $Ξ_{Q}$, $Ξ_{QQ^\prime}$, and $T_{QQ^\prime}$ ($Q,Q^\prime=c$ or $b$). The consequences of a partial restoration of chiral symmetry at the hadronization temperature are studied in detail.

hep-ph↗
arXiv2020

Stable bound states of $N$'s, $Λ$'s, and $Ξ$'s

We review our recent work about the stability of strange few-body systems containing $N$'s, $Λ$'s, and $Ξ$'s. We make use of local central Yukawa-type Malfliet-Tjon interactions reproducing the low-energy parameters and phase shifts of the nucleon-nucleon system and the latest updates of the hyperon-nucleon and hyperon-hyperon ESC08c Nijmegen potentials. We solve the three- and four-body bound-state problems by means of Faddeev equations and a generalized Gaussian variational method, respectively. The hypertriton, $Λnp$ $(I)J^P=(1/2)1/2^+$, is bound by 144 keV; the recently discussed $Λnn$ $(I)J^P=(1/2)1/2^+$ system is unbound, as well as the $ΛΛnn$ $(I)J^P=(1)0^+$system, being just above threshold. Our results indicate that the $ΞNN$, $ΞΞN$ and $ΞΞNN$ systems with maximal isospin might be bound.

nucl-th↗
arXiv2020

Neutral baryonic systems with strangeness

We review the status as regards the existence of three- and four-body bound states made of neutrons and $Λ$ hyperons. For interesting cases, the coupling to neutral baryonic systems made of charged particles of different strangeness has been addressed. There are strong arguments showing that the $Λnn$ system has no bound states. $ΛΛnn$ strong stable states are not favored by our current knowledge of the strangeness $-1$ and $-2$ baryon-baryon interactions. However, a possible $Ξ^- t$ quasibound state decaying to $ΛΛnn$ might exist in nature. Similarly, there is a broad agreement about the nonexistence of $ΛΛn$ bound states. However, the coupling to $ΞNN$ states opens the door to a resonance above the $ΛΛn$ threshold.

nucl-th↗
arXiv2019

$Ξ^- t$ quasibound state instead of $ΛΛnn$ bound state

We study the coupled $ΛΛnn-Ξ^- pnn$ system to check whether the inclusion of channel coupling is able to bind the $ΛΛnn$ system. We use a separable potential three-body model of the coupled $ΛΛnn - Ξ^- pnn$ system as well as a variational four-body calculation with realistic interactions. Our results exclude the possibility of a $ΛΛnn$ bound state by a large margin. However, we have found a $Ξ^- t$ quasibound state above the $ΛΛnn$ threshold.

nucl-th↗
arXiv2019

Spectroscopy, lifetime and decay modes of the $T^-_{bb}$ tetraquark

We present the first full-fledged study of the flavor-exotic isoscalar $T_{bb}^-\equiv b b \bar u \bar d$ tetraquark with spin and parity $J^P=1^+$. We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio $M_Q/m_q$ of the heavy to light quark masses. For such a standard constituent model, $T_{bb}^-$ lies approximately 150 MeV below the strong decay threshold $B^-\bar {B^*}^{0}$ and 105 MeV below the electromagnetic decay threshold $B^- \bar B^0 γ$. We evaluate the lifetime of $T_{bb}^-$, identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is $Γ\approx 87 \times 10^{-15}$ GeV and therefore its lifetime $τ\approx$ 7.6 ps. The promising final states are ${B^*}^{-}\, {D^*}^{+} \, \ell^- \, \bar ν_\ell$ and $\bar {B^*}^{0} \, {D^*}^{0} \, \ell^- \, \bar ν_\ell $ among the semileptonic decays, and ${B^*}^{-} \, {D^*}^{+} \, {D_s^*}^-$, $\bar {B^*}^{0} \, {D^*}^{0} \, {D_s^*}^- $, and ${B^*}^{-} \, {D^*}^{+} \, ρ^-$ among the nonleptonic ones. The semileptonic decay to the isoscalar $J^P=0^+$ tetraquark $T_{bc}^0$ is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector.

hep-ph↗
arXiv2019

Production of exotic tetraquarks $QQ\bar{q}\bar{q}$ in heavy-ion collisions at the LHC

We investigate the production of exotic tetraquarks, $QQ\bar{q}\bar{q} \equiv T_{QQ}$ ($Q=c$ or $b$ and $q=u$ or $d$), in relativistic heavy-ion collisions using the quark coalescence model. The $T_{QQ}$ yield is given by the overlap of the density matrix of the constituents in the emission source with the Wigner function of the produced tetraquark. The tetraquark wave function is obtained from exact solutions of the four-body problem using realistic constituent models. The production yields are typically one order of magnitude smaller than previous estimations based on simplified wave functions for the tetraquarks. We also evaluate the consequences of the partial restoration of chiral symmetry at the hadronization temperature on the coalescence probability. Such effects, in addition to increasing the stability of the tetraquarks, lead to an enhancement of the production yields, pointing towards an excellent discovery potential in forthcoming experiments. We discuss further consequences of our findings for the search of exotic tetraquarks in central Pb+Pb collisions at the LHC.

hep-ph↗
arXiv2019

Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap

A vortex in a Bose-Einstein condensate on a ring undergoes quantum dynamics in response to a quantum quench in terms of partial symmetry breaking from a uniform lattice to a biperiodic one. Neither the current, a macroscopic measure, nor fidelity, a microscopic measure, exhibit critical behavior. Instead, the symmetry memory succeeds in identifying the point at which the system begins to forget its initial symmetry state. We further identify a symmetry energy difference in the low lying excited states which trends with the symmetry memory.

cond-mat.quant-gas↗
arXiv2019

Pentaquarks with anticharm or beauty revisited

We use a constituent model to analyze the stability of pentaquark $\bar Q qqqq$ configurations with a heavy antiquark $\bar c$ or $\bar b$, and four light quarks $uuds$, $ddsu$ or $ssud$. The interplay between chromoelectric and chromomagnetic effects is not favorable, and, as a consequence, no bound state is found below the lowest dissociation threshold.

hep-ph↗
arXiv2018

Basics of doubly heavy tetraquarks

We outline the most important results regarding the stability of doubly heavy tetraquarks $QQ\bar q\bar q$ with an adequate treatment of the four-body dynamics. We consider both color-mixing and spin-dependent effects. Our results are straightforwardly applied to the case of all-heavy tetraquarks $QQ\bar Q\bar Q$. We conclude that the stability is favored in the limit $M_Q/m_q \gg 1$ pointing to the stability of the $bb\bar u\bar d$ state and the instability of all-heavy tetraquarks.

hep-ph↗
arXiv2018

Charmed baryons in nuclear matter

We study the temperature and baryon density dependence of the masses of the lightest charmed baryons $Λ_c$, $Σ_c$ and $Σ^*_c$. We also look at the effects of the temperature and baryon density on the binding energies of the $Λ_c N$ and $Λ_c Λ_c$ systems. Baryon masses and baryon-baryon interactions are evaluated within a chiral constituent quark model. Medium effects are incorporated in those parameters of the model related to the dynamical breaking of chiral symmetry, which are the masses of the constituent quarks, the $σ$ and $π$ meson masses, and quark-meson couplings. We find that while the in-medium $Λ_c$ mass decreases monotonically with temperature, those of $Σ_c$ and $Σ^*_c$ have a nonmonotonic dependence. These features can be understood in terms of a simple group theory analysis regarding the one-gluon exchange interaction in those hadrons. The in-medium $Λ_c N$ and $Λ_c Λ_c$ interactions are governed by a delicate balance involving a stronger attraction due to the decrease of the $σ$ meson mass, suppression of coupled-channel effects and lower thresholds, leading to shallow bound states with binding energies of a few~MeV. The $Λ_c$ baryon could possibly be bound to a large nucleus, in qualitative agreement with results based on relativistic mean field models or QCD sum rules. Ongoing experiments at RHIC or LHCb or the planned ones at FAIR and J-PARC may take advantage of the present results.

hep-ph↗
arXiv2017

Stable heavy pentaquarks in constituent models

It is shown that standard constituent quark models produce $(\bar c c qqq)$ hidden-charm pentaquarks, where $c$ denotes the charmed quark and $q$ a light quark, which lie below the lowest threshold for spontaneous dissociation and thus are stable in the limit where the internal $\bar c c$ annihilation is neglected. The binding is a cooperative effect of the chromoelectric and chromomagnetic components of the interaction, and it disappears in the static limit with a pure chromoelectric potential. Their wave function contains color sextet and color octet configurations for the subsystems and can hardly be reduced to a molecular state made of two interacting hadrons. These pentaquark states could be searched for in the experiments having discovered or confirmed the hidden-charm meson and baryon resonances.

hep-ph↗
arXiv2017

The ${}_{ΛΛ}^{\,\,\,\,4}n$ system

Using local central Yukawa-type Malfliet-Tjon interactions reproducing the low-energy parameters and phase shifs of the $nn$ system and the latest updates of the $nΛ$ and $ΛΛ$ Nijmegen ESC08c potentials we study the possible existence of a ${}_{ΛΛ}^{\,\,\,\,4}n$ bound state. Our results indicate that the ${}_{ΛΛ}^{\,\,\,\,4}n$ is unbound, being just above threshold. We discuss the role played by the $^1S_0$ $nn$ repulsive term of the Yukawa-type Malfliet-Tjon interaction.

nucl-th↗
arXiv2017

Workshop on Excited Hyperons in QCD Thermodynamics at Freeze-Out (YSTAR2016) Mini-Proceedings

This Workshop brought top experts, researchers, postdocs, and students from high-energy heavy ion interactions, lattice QCD and hadronic physics communities together. YSTAR2016 discussed the impact of "missing" hyperon resonances on QCD thermodynamics, on freeze-out in heavy ion collisions, on the evolution of early universe, and on the spectroscopy of strange particles. Recent studies that compared lattice QCD predictions of thermodynamic properties of quark-gluon plasma at freeze-out with calculations based on statistical hadron resonance gas models as well as experimentally measured ratios between yields of different hadron species in heavy ion collisions provide indirect evidence for the presence of "missing" resonances in all of these contexts. The aim of the YSTAR2016 Workshop was to sharpen these comparisons and advance our understanding of the formation of strange hadrons from quarks and gluons microseconds after the Big Bang and in todays experiments at LHC and RHIC as well as at future facilities like FAIR, J-PARC and KL at JLab. It was concluded that the new initiative to create a secondary beam of neutral kaons at JLab will make a bridge between the hardron spectroscopy, heavy-ion experiments and lattice QCD studies addressing some major issues related to thermodynamics of the early universe and cosmology in general.

hep-ph↗
arXiv2016

Doubly heavy baryon spectra guided by lattice QCD

This paper provides results for the ground state and excited spectra of three-flavored doubly heavy baryons, $bcn$ and $bcs$. We take advantage of the spin-independent interaction recently obtained to reconcile the lattice SU(3) QCD static potential and the results of nonperturbative lattice QCD for the triply heavy baryon spectra. We show that the spin-dependent potential might be constrained on the basis of nonperturbative lattice QCD results for the spin splittings of three-flavored doubly heavy baryons. Our results may also represent a challenge for future lattice QCD work, because a smaller lattice error could help in distinguishing between different prescriptions for the spin-dependent part of the interaction. Thus, by comparing with the reported baryon spectra obtained with parameters estimated from lattice QCD, one can challenge the precision of lattice calculations. The present work supports a coherent description of singly, doubly and triply heavy baryons with the same Cornell-like interacting potential. The possible experimental measurement of these states at LHCb is an incentive for this study.

hep-ph↗
arXiv2016

Maximal isospin few-body systems of nucleons and $Ξ$ hyperons

By using local central Yukawa-type interactions that reproduce the low-energy parameters of the latest updates of the Nijmegen ESC08c potentials we show that the $NΞ$, $NNΞ$, $NΞΞ$ and $NNΞΞ$ systems with maximal isospin are bound. Since in these states the strong decay $NΞ\toΛΛ$ is forbidden by isospin conservation, these strange few-body systems will be stable under the strong interaction. These results may suggest that other states with different number of $N$'s and $Ξ$'s in the maximal isospin channel could also be bound.

nucl-th↗
arXiv2016

Hadronic molecules with a ${\bar{D}}$ meson in a medium

We study the effect of a hot and dense medium on the binding energy of hadronic molecules with open-charm mesons. We focus on a recent chiral quark-model-based prediction of a molecular state in the $N \bar D$ system. We analyze how the two-body thresholds and the hadron-hadron interactions are modified when quark and meson masses and quark-meson couplings change in a function of the temperature and baryon density according to predictions of the Nambu--Jona-Lasinio model. We find that in some cases the molecular binding is enhanced in medium as compared to their free-space binding. We discuss the consequences of our findings for the search for exotic hadrons in high-energy heavy-ion collisions as well as in the forthcoming facilities FAIR or J-PARC.

hep-ph↗
arXiv2016

Search for doubly-heavy dibaryons in a quark model

We study the stability of hexaquark systems containing two heavy quarks and four light quarks within a simple quark model. No bound or metastable state is found. The reason stems on a delicate interplay between chromoelectric and chromomagnetic effects. Our calculation provides also information about anticharmed pentaquarks that are seemingly unbound in simple quark models.

hep-ph↗