The hyperon-nucleon (Y-N) interaction is important for the description of the equation-of-state of high baryon density matter. Hypernuclei, the cluster object of nucleons and hyperons, serve as cornerstones of a full understanding of the Y-N interaction. Recent measurements of the lightest known hypernucleus, the hypertriton's (HΛ3) and anti-hypertriton's (H¯Λ¯3) lifetime, mass and Λ separation energy have attracted interests on the subject. Its cross section and collective flow parameters have also been measured in heavy-ion collisions, which have revealed new features on its production mechanism. In this article we summarise recent measurements of HΛ3, focusing on the heavy-ion collisions. We will discuss their implications for the HΛ3 properties and the constrains on the Y-N interaction models.

The predictions of local realistic theories for the observables concerning the evolution of a $K^0\bar{K}^0$ quantum entangled pair (created in the decay of the $\phi$-meson) are discussed. It is shown, in agreement with Bell's theorem, that the most general local hidden-variable model fails in reproducing the whole set of quantum-mechanical joint probabilities. We achieve these conclusion by employing two different approaches. In a first one the local realistic observables are deduced from the most general premises concerning locality and realism, and Bell-like inequalities are not employed. The other approach makes use of Bell's inequalities. Within the former scheme, under particular conditions for the detection times, the discrepancy between quantum mechanics and local realism for the time-dependent asymmetry turns out to be not less than 20%. The same incompatibility can be made evident by means of a Bell-type test by employing both Wigner's and (once properly normalized probabilities are used) Clauser-Holt-Shimony-Holt's inequalities. Because of the relatively low experimental accuracy, the data obtained by the CPLEAR collaboration for the asymmetry parameter do not allow for a decisive test of local realism. Such a test, both with and without the use of Bell's inequalities, should be feasible in the future at the Frascati $\Phi$-factory.

Marcus Laurence Elwin “Mark” Oliphant, a leader during World War II in both radar development and the separation of uranium-235 for the atomic bomb, died on 14 July 2000 in Canberra, Australia, of natural causes.Oliphant was born in Adelaide, South Australia, on 9 October 1901. In 1927, he received an MSc in physics at Adelaide University and won an 1851 Exhibition scholarship for research abroad. He joined Ernest Rutherford’s group at the Cavendish Laboratory in Cambridge, England. He received a PhD in physics there in 1929; his thesis topic was the interaction of positive ions with metal surfaces. In 1932, Oliphant began nuclear research with Rutherford, using 0.5 milliliters of heavy water given to Rutherford by Gilbert Lewis of the University of California, Berkeley. With a 300-keV accelerator, Oliphant and Rutherford investigated the transmutation of light nuclei, bombarding them with protons and deuterons (heavy hydrogen). Remarkably, with deuterated targets, “protons” of anomalously large range were emitted jointly with very slow protons. Oliphant and Rutherford realized that these “protons” were “still-heavier hydrogen,” which they named “tritium,” and that the “alpha particles” they saw were helium-3. Oliphant joined Birmingham University in 1937 as Poynting Professor of Physics. While visiting primitive radar stations around Britain’s coast, he realized that much finer radar was needed urgently. Early in 1939, he obtained a grant from the British Admiralty to develop radar with a wavelength less than 10 cm; the best available at the time was 150 cm.That same year, he visited the Radiation Laboratory at Berkeley, California, where he met Ernest Lawrence, who would become a major influence in Oliphant’s life. Oliphant was impressed by Lawrence’s 60-inch cyclotron. Lawrence kindly gave him a complete set of specifications. In mid-1939, having gained funding, Oliphant began to build a 60-inch cyclotron at Birmingham. This project progressed slowly because of the war. An internal beam was achieved in 1950.Congratulating Lawrence on his 1939 Nobel Prize in Physics for the invention of the cyclotron, Oliphant wrote, “[Your Nobel] Prize shows that the technical side of the subject is now recognized as of equal importance to the advances that follow from [their use].” This view would soon govern Oliphant’s scientific life.On radar research at Birmingham, John Randall and Harry Boot soon invented the resonant-cavity magnetron. In early 1940, their model achieved the wavelengths needed. The magnetron’s power was soon increased 100-fold, and Birmingham concentrated on magnetron development. The first operational magnetrons were delivered to the US in August 1941.Also at Birmingham, in 1940, Otto Frisch and Rudolf Peierls had calculated that production of a uranium-235 atomic bomb of modest size was quite feasible. Oliphant took their memorandum at once to higher authority. A committee, code-named MAUD, discussed the memo and sent a report to the US “uranium committee” around June 1941; no reply came. When Oliphant visited the US in August, he found that the uranium committee secretary had simply locked the memo in his safe, telling nobody, because the US was “not at war.” Oliphant found little interest in atomic bombs among the physicists, most thinking them improbable. Only when Oliphant visited Lawrence in September did he get any response, which prompted him to give Lawrence a brief summary of the MAUD report. Lawrence then took Oliphant’s story directly to James Conant, chairman of the US National Defense Research Council, and Arthur Compton, provost at the University of Chicago, and convinced them that they should take the British work very seriously.In November 1943, Oliphant moved to work on the Manhattan Project, joining Lawrence’s group on electromagnetic separation of 235U from 238U for the atomic bomb. Most of his time was spent either at Berkeley or at Oak Ridge, Tennessee. He resigned from the Manhattan Project in January 1945, returning to Birmingham. He received funds from the postwar UK atomic energy committee for a 1-GeV proton synchrotron at Birmingham. He later (1950) left Birmingham for Canberra with key technicians. The proton synchrotron’s chief designer died in 1950, and Philip Moon completed its construction in 1953.When Oliphant learned details of the sufferings of the Hiroshima and Nagasaki populations, following the detonation of the two atomic bombs, he was appalled, feeling deeply guilty about his part in constructing the bombs. Concluding that all war was evil, he cut his links with military work. He came to believe that scientists must become more concerned about the social effects of their work. He became a founding member of the Pugwash Movement, attending the first three Pugwash conferences (between 1957 and 1958). He participated in another run of four conferences (1961–64). An impressive individual, tall with thick, white hair, he spoke convincingly and energetically; he described himself as “a belligerent pacifist.”The Australian government wished to found an Australian National University (ANU), dominantly for research, and formed a committee (which included Oliphant) to plan this ANU project. In 1950, Oliphant became the research director for ANU’s physical sciences division and the professor of particle physics. He required funding for a new accelerator there; the funding was granted to him. The purpose of Oliphant’s accelerator was to produce 10-GeV protons at low cost. The high cost of iron magnets favored the choice of an air-cored synchrotron structure; the high magnetic fields needed for accelerating the protons in the synchrotron would be generated by the electric currents resulting from the short-circuiting of a power supply. For this source, he built a homopolar generator (HPG) on-site. The HPG could be energized in 10 minutes by electricity mains, and then short-circuited. The final accelerated proton beam would then emerge in pulses of six per hour, an unusually low repetition rate. Oliphant argued that these 10-GeV protons, although few, would carry vital new information.Quite early, Oliphant believed that the currents received from the HPG would be so large—outside engineering experience—that their collection would require the use of liquid-jet brushes. He opted for a mixture of sodium and potassium, NaK—liquid at room temperature, but a dangerous material. In 1962, the HPG ran regularly, until an explosion occurred, resulting in serious injury even though safety regulations were followed. After an inquiry, in which Oliphant and his coworkers were exonerated, one coworker tried conventional (copper–graphite) brushes, which worked smoothly and have continued to do so.An external report, obtained for ANU, on the accelerator project indicated that the HPG was “hopelessly inadequate” for its original purpose. Oliphant’s group began to go their various ways. He resigned his directorship in 1963. Until his retirement in 1967, he worked as a research professor on ionized gases.In retirement Oliphant remained a public figure. He wrote articles on physics topics, published in the newspapers and in popular journals, and participated with zest in public debates on issues of general interest. He was frequently asked to give funeral and university orations. In 1972, he began a five-year appointment as the governor of South Australia. He was an open-minded governor and became popular with the public. In 1977, he participated in his last Pugwash conference, held in Munich. His activities continued but gradually diminished, although the impulse was always there. Marcus L. E. “Mark” Oliphant PPT|High resolution© 2001 American Institute of Physics.

We have carried out Monte Carlo calculations on two sets of randomly generated QCD events due to p (p) over bar --> t (t) over bar with top mass m(t) = 170 GeV, one set leading to e(+)e(-) or e(+/-)mu(-/+) or mu(+)mu(-) 2-jets (dilepton) and the other leading to e(+/-) or mu(+/-) 4-jets (unilepton) configurations, in order to test the likelihood methods we have proposed for determining the top mass by analyses of these two sets of configurations. For the set of unilepton events, our method gives a very efficient and quite sharp measure of the top mass lying several GeV below the input mass. For the dilepton set, our method gives a much broader and markedly asymmetric distribution for the top mass estimates, 75% of them lying below 170 GeV, but the dilepton data will have much lower background than unilepton data. We then illustrate these methods by applying them to the data available from CDF in 1995 and discuss the results obtained in relation to the results for the sets of Monte Carlo events. The dilepton events from CDF and DO more recently yield masses spread widely, from 130 to 180 GeV, generally lower than the CDF unilepton events, which cluster around 175 +/- 8 GeV. In an appendix, we discuss the nature of the additional 'slow' mu(+) observed in one CDF dilepton event, concluding that it is most probably a 'tertiary lepton' resulting from the decay sequence b --> c + hadrons, followed by c --> s mu(+)nu(mu).

The substitutional states (1p)(h)(1p)(Lambda) are readily formed in (K-,pi(-)) reactions on target p-shell nuclei AZ. By chance, a number of these states can be studied empirically with high precision using the at-rest K- --> pi(-) reaction on C-12 and O-16 nuclei in nuclear emulsion, possible because of a window for the states (A)(Lambda)Z* between the thresholds (Lambda+((A-1)) Z) and (p+((A-1))(Lambda)(Z-1)). We calculate the mean spin-orbit interaction delta(Lambda) for Lambda-C-12 and Lambda-O-16 for three Nijmegen Lambda N potentials, using it to discuss these energy levels, (0(1)(+), 2(1)(+), & 2(2)(+) for C-12(Lambda)*), and (0(1)(+), 2(1)(+) for O-16(Lambda)*) jointly with data on three related levels (0(2)(+), 2(2)(+), & 2(3)(+) for O-16(Lambda)*) lying outside its window.

An analysis of emulsion data on the K- meson capture reaction on oxygen, K-16O --> pi(-) p(Lambda)(15)N reveals the formation of two intermediate states of the hypernucleus O-16(Lambda)* which subsequently decay by proton emission. The states are relatively broad, as expected for e-values of a few MeV, and are attributed to the 0(+) and 2(+) levels of O-16(Lambda) from the configurations [(P-1/2)(N)(-1) (P-1/2,P-3/2)(Lambda)] with it-binding energies equal to 1.54 +/- 0.09 MeV and 3.10 +/- 0.08 MeV, respectively, where B-Lambda for 15(Lambda)N is 13.59 MeV. The 2(+)-0(+) B-Lambda difference is almost independent of the present statistical error (+/-0.15 MeV) on B-Lambda(N-15(Lambda)). Provided the state more abundantly produced is assigned to the 2(+) level, their relative positions and production rates agree well with the theoretical predictions, A comparison with results from counter experiments is made. The extraction of the it spin-orbit splitting from the 2(+)-0(+) energy difference is discussed using calculations for several different Lambda N potentials. (C) 1997 Elsevier Science B.V.

The KNBAR interactions are so strong that the K--helium wavefunctions for at-rest capture have more structure than is commonly assumed. Its effect on the reaction rates and spectra is illustrated for our simplified model of (3N)-Y interactions using Yamaguchi potentials. For (ns) capture (n greater-than-or-equal-to 2), this model gives a fair qualitative fit to the helium bubble chamber data. We conclude that the spectrum observed just below the (3N)-SIGMA threshold does not require a He-4SIGMA bound state, although it calls for some additional attraction. This model actually excludes contributions from such a state, but this may only reflect its simplicity; more flexible models need to be explored. Comparison with the KEK at-rest spectrum and the BNL-KEK in-flight spectrum is briefly discussed.

We have analyzed the available data on $p\bar{p}\,\rightarrow\, t\, \bar{t}$ followed by the decays ($t\rightarrow bW^{+},\: \bar{t}\rightarrow \bar{b}W^{-}$) which lead to $e^{\pm}\mu^{\mp}2 \mathrm{jets}$ or $l^{\pm}4 \mathrm{jets}$ configurations, using a likelihood method we proposed earlier. The outcome is compared with the recent CDF analysis. In an appendix, we discuss the nature of the additional ``slow'' $\mu^{+}$ observed in one CDF dilepton event, concluding that it is most probably a ``tertiary lepton'' resulting from the decay sequence $b\rightarrow c +\mathrm{hadrons}$, followed by $c\rightarrow s \mu^{+} \nu$.

This paper reviews briefly the history of the data and the arguments which led to the conclusion in 1956 that the θ‐ and τ‐modes of K+ decay led to final states which (for the same spin value) did not have the same parity, the puzzle concerning their relationship which led to the Lee‐Yang hypothesis that parity is not conserved in the weak interactions. It discusses also an alternative line of argument and experiment which might have been followed up at that time, and the possible reasons why physicists were so reluctant to embrace parity non‐conservation.

Possibilities are discussed for determining the top quark mass $m_t$ from observations on the decay processes for top-antitop pairs produced in antiproton-proton collisions, assuming that the $t \to bW^+$ decay channel is dominant and much faster than hadronization. The final states $t \bar{t} \to \bar{b} b \mu^\pm e^\mp$ provide the most striking signal, with little background, but they are rare ($\approx 2/81$). If all candidate events prove to be from $t \bar{t}$, an estimate follows for $P(m_t|rate)$, the probability distribution for $m_t$. The one reported configuration allows an independent estimate for $P(m_t|\mu^\pm e^\mp \,2jets)$. These two distributions are compatible,yielding an estimate of about 122 GeV. Decay events ``1 energetic lepton($l$) + 4jets'' should appear twelve times as often as ``$\mu^\pm e^\mp \,2jets$'' events and can be analysed to give estimates for $P(m_t|l\, 4jets)$. There may be background from non-top events but suitable cuts on the data and our analysis procedure together reduce this to a low level. The rate observed for these events does not appear to be as large as this factor 12. Identification of either or both of the $(b \bar{b})$ jets would be a great step forward. We advocate an energetic approach to the analysis of individual events on an event by event basis, with the hope of finding a subgroup of events with a common mass estimate.

A method is introduced for separating top quark production from Standard Model background in the channel in which one top quark decays semi‐leptonically and its anti‐quark decays hadronically into three jets. The method is applied to simulated CDF data and discriminates top (with mt≥120 GeV) from background.