Vortex Quantum Droplets under Competing Nonlinearities

This concise review summarizes recent advancements in theoretical studies of vortex quantum droplets(VQDs)in matter-wave fields.These are robust self-trapped vortical states in two-and three-dimensional(2D and 3D)Bose–Einstein condensates(BECs)with intrinsic nonlinearity.Stability of VQDs is provided by additional nonlinearities resulting from quantum fluctuations around mean-field states,often referred to as the Lee–Huang–Yang(LHY)corrections.The basic models are presented,with emphasis on the interplay between the mean-field nonlinearity,LHY correction,and spatial dimension,which determines the structure and stability of VQDs.We embark by delineating fundamental properties of VQDs in the 3D free space,followed by consideration of their counterparts in the 2D setting.Additionally,we address stabilization of matter-wave VQDs by optical potentials.Finally,we summarize results for the study of VQDs in the single-component BEC of atoms carrying magnetic moments.In that case,the anisotropy of the long-range dipole-dipole interactions endows the VQDs with unique characteristics.The results produced by the theoretical studies in this area directly propose experiments for the observation of novel physical effects in the realm of quantum matter,and suggest potential applications to the design of new schemes for processing classical and quantum information.

Two-dimensional anisotropic vortex quantum droplets in dipolar Bose−Einstein condensates

Creation of stable intrinsically anisotropic self-bound states with embedded vorticity is a challenging issue.Previously,no such states in Bose−Einstein condensates(BECs)or other physical settings were known.Dipolar BEC suggests a unique possibility to predict stable two dimensional anisotropic vortex quantum droplets(2D-AVQDs).We demonstrate that they can be created with the vortex axis oriented perpendicular to the polarization of dipoles.The stability area and characteristics of the 2D-AVQDs in the parameter space are revealed by means of analytical and numerical methods.Further,the rotation of the polarizing magnetic field is considered,and the largest angular velocities,up to which spinning 2D-AVQDs can follow the rotation in clockwise and anti-clockwise directions,are found.Collisions between moving 2D-AVQDs are studied too,demonstrating formation of bound states with a vortex−antivortex−vortex structure.A stability domain for such stationary bound states is identified.Unstable dipolar states,that can be readily implemented by means of phase imprinting,quickly transform into robust 2D-AVQDs,which suggests a straightforward possibility for the creation of these states in the experiment.

Driving factors behind multiple populations

Star clusters were historically considered simple stellar populations,with all stars sharing the same age and initial chemical composition.However,the presence of chemical anomalies in globular clusters(GCs),called multiple stellar populations(MPs),has challenged star formation theories in dense environments.Literature studies show that mass,metallicity,and age are likely controlling parameters for the manifestation of MPs.Identifying the limit between clusters with/without MPs in physical parameter space is crucial to reveal the driving mechanism behind their presence.In this study,we look for MP signals in Whiting 1,which is traditionally considered a young GC.Using the Magellan telescope,we obtained low-resolution spectra withinλλ=3850-5500?for eight giants of Whiting 1.We measured the C and N abundances from the CN and CH spectral indices.C and N abundances have variations comparable with their measurement errors(~0.1 dex),suggesting that MPs are absent from Whiting 1.Combining these findings with literature studies,we propose a limit in the metallicity vs.cluster compactness index parameter space,which relatively clearly separates star clusters with/without MPs(GCs/open clusters).This limit is physically motivated.On a larger scale,the galactic environment determines cluster compactness and metallicity,leading to metal-rich,diffuse,old clusters formed ex situ.Our proposed limit also impacts our understanding of the formation of the Sagittarius dwarf galaxy:star clusters formed after the first starburst(age≤8-10 Gyr).These clusters are simple stellar populations because the enriched galactic environment is no longer suitable for MP formation.

Determination of the number ofψ(3686)events taken at BESⅢ

The number ofψ(3686)events collected by the BESⅢdetector during the 2021 run period is determined to be(2259.3±11.1)×10~6 by counting inclusiveψ(3686)hadronic events.The uncertainty is systematic and the statistical uncertainty is negligible.Meanwhile,the numbers ofψ(3686)events collected during the 2009 and 2012run periods are updated to be(107.7±0.6)×10~6 and(345.4±2.6)×10~6,respectively.Both numbers are consistent with the previous measurements within one standard deviation.The total number ofψ(3686)events in the three data samples is(2712.4±14.3)×10~6.

Search for hidden-charm tetraquark with strangeness in e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.

We report a search for a heavier partner of the recently observed Z_(cs)(3985)^(-) state,denoted as Z_(cs)^('-),in the process e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.,based on e^(*)e^(-)collision data collected at the center-of-mass energies of √s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Z_(cs)^('-) is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K^(+)recoil-mass spectra,which are probed for a potential contribution from Z_(cs)^('-)→D_(s)^(∗−) D^(∗0 )+ c.c.We find an excess of Z_(cs)^('-)→D_(s)^(*-)-D^(*0)(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7_(sat)±4.7_(syst.))MeV/c^(2).As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σ^(Borm))and the branching fraction(B)of Z_(cs)^('-)→D_(s)^(*-)-D^(*0),under different assumptions of the Z_(cs)^('-) mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits of σ^(Born).B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Z_(cs)^('-) state and clarify its nature in the coming years.

A new form of liquid matter:Quantum droplets

This brief review summarizes recent theoretical and experimental results which predict and establish the existence of quantum droplets(QDs),i.e.,robust two-and three-dimensional(2D and 3D)self-trapped states in Bose-Einstein condensates(BECs),which are stabilized by effective self-repulsion induced by quantum fluctuations around the mean-field(MF)states[alias the Lee-Huang-Yang(LHY)effect].The basic models are presented,taking special care of the dimension crossover,2D→3D.Recently reported experimental results,which exhibit stable 3D and quasi-2D QDs in binary BECs,with the inter-component attraction slightly exceeding the MF self-repulsion in each component,and in single-component condensates of atoms carrying permanent magnetic moments,are presented in some detail.The summary of theoretical results is focused,chiefly,on 3D and quasi-2D QDs with embedded vorticity,as the possibility to stabilize such states is a remarkable prediction.Stable vortex states are presented both for QDs in free space,and for singular but physically relevant 2D modes pulled to the center by the inverse-square potential,with the quantum collapse suppressed by the LHY effect.

Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at √sNN=200 GeV

High transverse momentum(pT)particle production is suppressed owing to the parton(jet)energy loss in the hot dense medium created in relativistic heavy-ion collisions.Redistribution of energy at low-to-modest pT has been difficult to measure,owing to large anisotropic backgrounds.We report a data-driven method for background evaluation and subtraction,exploiting the away-side pseudorapidity gaps,to measure the jetlike correlation shape in Au+Au collisions at √sNN=200 GeV in the STAR experiment.The correlation shapes,for trigger particles pT>3GeV/c and various associated particle pT ranges within 0.5<pT<10GeV/c,are consistent with Gaussians,and their widths increase with centrality.The results indicate jet broadening in the medium created in central heavy-ion collisions.

Oil emulsions in naturally fractured Porous Media

Most of the studies regarding the formation and stability of emulsions focus on the conditioning and management of crude oil on surface facilities.Since a great deal of the crude oil produced is in the form of stable emulsions,it is often claimed that these emulsions are formed through chokes and other flow constrictions in oil field equipment.However,emulsions are produced in wells,which not only lack these constrictions but also are produced at low flow rates,demonstrating the fact that emulsions can be formed within the well itself.The present work reviews the literature regarding the formation and properties of heavy and extra-heavy oil emulsions in naturally fractured porous media due to the current relevance that these types of crude oil exploitation take,satisfying the hydrocarbon energy demand.Moreover,emulsions have received more attention recently since they can be formed in-situ and improve oil recovery.To understand the flow mechanics of emulsions in porous media,different models to describe their transportation are presented.Finally,the formation of emulsions in the reservoir for enhanced oil recovery purposes,including the use of nanoparticlestabilized emulsions is discussed.