The STAR CollaborationNuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons -composed of an antiproton, antineutron, and antilambda hyperon -produced by colliding gold nuclei at high energy. Our analysis yields 70 ± 17 antihypertritons ( Nuclei are abundant in the universe, but antinuclei that are heavier than the antiproton have been observed only as products of interactions at particle accelerators (1, 2). Collisions of heavy nuclei at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) briefly produce hot and dense matter that has been interpreted as a quark gluon plasma (QGP) (3, 4) with an energy density similar to that of the universe a few microseconds after the Big Bang. This plasma contains roughly equal numbers of quarks and antiquarks. As a result of the high energy density of the QGP phase, many strange-antistrange (ss) quark pairs 1 are liberated from the quantum vacuum. The plasma cools and transitions into a hadron gas, producing nucleons, hyperons, mesons, and their antiparticles.Nucleons (protons and neutrons) contain only up and down valence quarks, while hyperons (Λ, Σ, Ξ, Ω) contain at least one strange quark in its 3-quark valence set. A hypernucleus is a nucleus that contains at least one hyperon in addition to nucleons. All hyperons are unstable, even when bound in nuclei. The lightest bound hypernucleus is the hypertriton ( 3 Λ H), which consists of a Λ hyperon, a proton, and a neutron. The first observation of any hypernucleus was made in 1952 using a nuclear emulsion cosmic ray detector (5). Here, we present the observation of an antimatter hypernucleus. Production of antinuclei:Models of heavy-ion collisions have had good success in explaining the production of nuclei by assuming that a statistical coalescence mechanism is in effect during the late stage of the collision evolution (4, 6). Antinuclei can be produced through the same coalescence mechanism, and are predicted to be present in cosmic rays. An observed high yield could be interpreted as an indirect signature of new physics, such as Dark Matter (7, 8). Heavy-ion collisions at RHIC provide an opportunity for the discovery and study of many antinuclei and antihypernuclei.The ability to produce antihypernuclei allows the study of all populated regions in the 3-dimensional chart of the nuclides. The conventional 2-dimensional chart of the nuclides organizes nuclear isotopes in the (N, Z) plane, where N is the number of neutrons and the Z is the number of protons in the nucleus. This chart can be extended to the negative sector in the (N, Z) plane by including antimatter nuclei. Hypernuclei bring a third dimension into play, based on the strangeness quantum number of the nucleus. The present study probes the territory of antinuclei with non-zero strangeness ( Fig. 1), where proposed ideas (9-12) related to t...

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Abstract.As climate change has occurred over east Asia since the 1950s, intense interest and debate have arisen concerning the contribution of human activities to the observed warming in past decades. In this study, we investigate regional surface temperature change during the boreal cold season using a recently developed methodology that can successfully identify and separate the dynamically induced temperature (DIT) and radiatively forced temperature (RFT) changes in raw surface air temperature (SAT) data. For regional averages, DIT and RFT contribute 44 and 56 % to the SAT over east Asia, respectively. The DIT changes dominate the SAT decadal variability and are mainly determined by internal climate variability, represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). Radiatively forced SAT changes have made a major contribution to the global-scale warming trend and the regionalscale enhanced semi-arid warming (ESAW). Such enhanced warming is also found in radiatively forced daily maximum and minimum SAT. The long-term global-mean SAT warming trend is mainly related to radiative forcing produced by global well-mixed greenhouse gases. The regional anthropogenic radiative forcing, however, caused the enhanced warming in the semi-arid region, which may be closely associated with local human activities. Finally, the relationship between the so-called "global warming hiatus" and regional enhanced warming is discussed.