We report the measurement of K*0 meson at midrapidity (|y|< 1.0) in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV collected by the STAR experiment during the RHIC beam ...energy scan (BES) program. The transverse momentum spectra, yield, and average transverse momentum of K*0 are presented as functions of collision centrality and beam energy. The K*0/K yield ratios are presented for different collision centrality intervals and beam energies. The K*0/K ratio in heavy-ion collisions are observed to be smaller than that in small system collisions (e+e and p+p). The K*0/K ratio follows a similar centrality dependence to that observed in previous RHIC and LHC measurements. The data favor the scenario of the dominance of hadronic re-scattering over regeneration for K*0 production in the hadronic phase of the medium.
Background
Acute lower respiratory infection (ALRI) is the leading cause of child mortality, especially in the developing world. Polymorphisms in the interleukin 4 (IL‐4) gene have been linked to a ...variety of human diseases.
Objectives
To investigate whether the IL‐4 ‐590C/T (rs2243250) polymorphism could be a genetic marker for susceptibility to ALRIs in young Egyptian children.
Methods
This was a multicenter study conducted on 480 children diagnosed with pneumonia or bronchiolitis, and 480 well‐matched healthy control children. Using PCR‐RFLP analysis, we genotyped a ‐590C/T (rs2243250) single nucleotide polymorphism of the IL‐4 gene promoter, meanwhile the serum IL‐4concentration was measured by ELISA.
Results
The frequency of the IL‐4 ‐590 T/T genotype and T allele were overrepresented in patients with ALRIs in comparison to the control group (OR = 2.0; 95% confidence interval CI: 1.38‐2.96; for the T/T genotype) and (OR: 1.3; 95%CI: 1.07‐1.56; for the T allele; P < 0.01). The IL‐4 ‐590 T/T genotype was associated with significantly higher mean serum IL‐4 concentration (58.7 ± 13.4 pg/mL) compared to the C/T genotype (47.6 ± 11 pg/mL) and the C/C genotype (34.8 ± 9.6 pg/mL); P < 0.01.
Conclusion
The IL‐4 −590C/T (rs2243250) polymorphism may contribute to susceptibility to ALRIs in young Egyptian children.
Here, we report a measurement of cumulants and correlation functions of event-by-event proton multiplicity distributions from fixed-target Au+Au collisions at $\sqrt{s_\text{NN}}$ = 3 GeV measured by ...the STAR experiment. Protons are identified within the rapidity (y) and transverse momentum ($p_T$) region –0:9 < $\textit{y}$ < 0 and 0:4 < pT < 2:0 GeV/c in the center-of-mass frame. A systematic analysis of the proton cumulants and correlation functions up to sixth-order as well as the corresponding ratios as a function of the collision centrality, $p_T$, and $\textit{y}$ are presented. The effect of pileup and initial volume fluctuations on these observables and the respective corrections are discussed in detail. The results are compared to calculations from the hadronic transport UrQMD model as well as a hydrodynamic model. In the most central 5% collisions, the value of proton cumulant ratio $C_4 = C_2$ is negative, drastically different from the values observed in Au+Au collisions at higher energies. Compared to model calculations including Lattice QCD, a hadronic transport model, and a hydrodynamic model, the strong suppression in the ratio of $C_4/C_2$ at 3 GeV Au+Au collisions indicates an energy regime dominated by hadronic interactions.
We report the first multi-differential measurements of strange hadrons of K-, φ and Ξ - yields as well as the ratios of φ/K-and φ/Ξ - in Au+Au collisions at √ sNN = 3 GeV with the STAR experiment ...fixed target configuration at RHIC. The φ mesons and Ξ - hyperons are measured through hadronic decay channels, φ → K+K- and Ξ - → Λπ -. Collision centrality and rapidity dependence of the transverse momentum 3 spectra for these strange hadrons are presented. The 4π yields and ratios are compared to thermal model and hadronic transport model predictions. At this collision energy, thermal model with grand canonical ensemble (GCE) under-predicts the φ/K- and φ/Ξ - ratios while the result of canonical ensemble (CE) calculations reproduce φ/K-, with the correlation length rc ~ 2.7 fm, and φ/Ξ -, rc ~ 4.2 fm, for the 0-10% central collisions. Hadronic transport models including high mass resonance decays could also describe the ratios. While thermal calculations with GCE work well for strangeness production in high energy collisions, the change to CE at 3 GeV implies a rather different medium property at high baryon density.
Measurements of mass and Λ binding energy of $^{4}_{Λ}$H and $^{4}_{Λ}$He in Au+Au collisions at $\sqrt{s_{NN}}$ = 3 GeV are presented, with an aim to address the charge symmetry breaking (CSB) ...problem in hypernuclei systems with atomic number A = 4. The Λ binding energies are measured to be 2.22±0.06(stat.)±0.14(syst.) MeV and 2.38±0.13(stat.)±0.12(syst.) MeV for $^{4}_{Λ}$H and $^{4}_{Λ}$He, respectively. The measured Λ binding-energy difference is 0.16±0.14(stat.)±0.10(syst.) MeV for ground states. Combined with the γ-ray transition energies, the binding-energy difference for excited states is –0.16±0.14(stat.)±0.10(syst.) MeV, which is negative and comparable to the value of the ground states within uncertainties. These new measurements on the Λ binding-energy difference in A = 4 hypernuclei systems are consistent with the theoretical calculations that result in ΔB$^{4}_{Λ}$($1^{+}_{exc}$) ≈ –ΔB$^{4}_{Λ}$($0^{+}_{g.s.}$) < 0 and present a new method for the study of CSB effect using relativistic heavy-ion collisions.
We report a new measurement of the production cross section for inclusive electrons from open heavy-flavor hadron decays as a function of transverse momentum (pT) at midrapidity (|y| < 0.7) in p + p ...collisions at √s = 200 GeV. Overall, the result is presented for 2.5 < PT < 10 GeV/c with an improved precision above 6 GeV/c with respect to the previous measurements, providing more constraints on perturbative QCD calculations. Moreover, this measurement also provides a high-precision reference for measurements of nuclear modification factors for inclusive electrons from open-charm and -bottom hadron decays in heavy-ion collisions.
We report on the measurements of directed flow and elliptic flow $ν_{2}$ for hadrons ($π^{±}$, $Κ^{±}$, $Κ^{0}_{s}$, p, φ, Λ and $Ξ^{-}$) from Au+Au collisions at $ \sqrt{s_{NN}}$ = 3 GeV and for ...($π^{±}$, $Κ^{±}$, $p$ and $\bar{p}$) at 27 and 54.4 GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3 GeV the at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative $ν_{2}$ and positive $ν_{1}$ slope at 3 GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.
