Comparison of strange antibaryon and strange meson production inK + p interactions at 32 GeV/c

New experimental results are presented on inclusive production properties of \(\bar \Sigma ^{ * + } \) (1385) and \(\bar \Sigma ^{ * + } \) (1385) inK ⁺ p interactions at 32 GeV/c. The analysis is based on significantly larger statistics than previously available. A comparison is also made of invariantx-distributions ofK ⁰/ \(\bar K^0 \) , \(\bar \Lambda \) and \(\bar \Xi ^ + \) and of \(\bar \Sigma ^{ * \pm } \) (1385) andK ^*+(892). These spectra exhibit regularities expected from the quark-recombination picture when it is assumed that the strange mesons and antibaryons are produced off the strange \(\bar s\) -valence-quark in the incidentK ⁺ meson. Transverse momentum distributions are also presented forK ^*+(892) and \(\bar \Sigma ^{ * \pm } \) (1385) and found to be very similar. The results on strange antibaryon average multiplicities disagree strongly with a recent version of the additive quark model.     

Charged hadron multiplicities in high energy\bar v_\mu n and\bar v_\mu pinteractions

Charged hadron multiplicity distributions in \(\bar v_\mu n\) and \(\bar v_\mu p\) interactions in the energy range \(5< E_{\bar v}< 150GeV\) GeV are presented. They are obtained from about \(6000\bar v_\mu \) charged current events produced in BEBC filled with deuterium. Multiplicity moments are studied as a function of the invariant mass of the hadronic systemW. Results on multiplicity distributions in the forward and backward directions in the hadronic c.m.s. are presented and discussed within the framework of the quark parton model. Values for the average charge of the forward jet are also determined and compared with other experimental data.     

\bar \Lambda Production inK − p interactions at 32 GeV/c

Antilambda production is studied inK ^? p interactions at 32 GeV/c. Both total and differential cross sections are presented. The inclusive \(\bar \Lambda \) production cross section amounts to 109±7 μb. A remarkable energy dependence is observed, σ( \(\bar \Lambda \) ) increasing by a factor of four between 14.3 and 32 GeV/c. Thep _⊥ ² distribution exhibits an exponential fall-off with a slope of 3.3±0.2 (GeV/c)^?2. Most of the \(\bar \Lambda \) 's are emitted in the forward hemisphere. The invariantx distribution increases between 14.3 and 32 GeV/c. Data are presented for \(\bar \Lambda \) production inK ^- p→Λ \(\bar \Lambda \) +X K ^- p→ \(\bar \Lambda \) K ⁿ +X, andK ^- p→ \(\bar \Lambda \) p+X.     

Status of the scalar singlet dark matter model

One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a \(\mathbb {Z}_2\) symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. We include the dark matter relic density measured by Planck, direct searches with LUX, PandaX, SuperCDMS and XENON100, limits on invisible Higgs decays from the Large Hadron Collider, searches for high-energy neutrinos from dark matter annihilation in the Sun with IceCube, and searches for gamma rays from annihilation in dwarf galaxies with the Fermi-LAT. Viable solutions remain at couplings of order unity, for singlet masses between the Higgs mass and about 300 GeV, and at masses above \(\sim \)1 TeV. Only in the latter case can the scalar singlet constitute all of dark matter. Frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the Higgs, can also account for all of dark matter, and remains viable. However, Bayesian considerations show this region to be rather fine-tuned.     

Solar Modulation of <Superscript>2</Superscript>H/<Superscript>1</Superscript>H and <Superscript>3</Superscript>He/<Superscript>4</Superscript>He according to Data Obtained in the PAMELA Satellite-Borne Experiment between 2006 and 2014

Preliminary results of measurements of the solar modulation of the isotopic hydrogen and helium content in galactic cosmic rays are presented for the first time. These data were obtained between 2006 and 2014 in the PAMELA international orbital experiment via measuring the time of flight of nuclei in the Pamela scintillation telescope and via analyzing, in the multilayered calorimeter of the PAMELA magnetic spectrometer, ionization losses of nuclei whose rigidity was known from trajectory measurements and which traversed the instrument without undergoing nuclear interactions. The results of these measurements are compared with existing experimental and calculated data, which are quite scanty.     

QCD thermodynamics at zero and non-zero density

We present results on the QCD equation of state, obtained with two different improved dynamical staggered fermion actions and almost physical quark masses. Lattice cut-off effects are discussed in detail as results for three different lattice spacings are available now, i.e. results have been obtained on lattices with temporal extent of N_τ = 4, 6 and 8. Furthermore we discuss the Taylor expansion approach to non-zero baryon chemical potential by means of an expansion of the pressure. We use the expansion coefficients to calculate various fluctuations and correlations among hadronic charges. We find that the correlations reproduce the qualitative behavior of the resonance gas model below T_c and start to agree with the free gas predictions for T1.5T_c.     

Temporally controlled modulation of antihydrogen production and the temperature scaling of antiproton-positron recombination

We demonstrate temporally controlled modulation of cold antihydrogen production by periodic RF heating of a positron plasma during antiproton-positron mixing in a Penning trap. Our observations have established a pulsed source of atomic antimatter, with a rise time of about 1 s, and a pulse length ranging from 3 to 100 s. Time-sensitive antihydrogen detection and positron plasma diagnostics, both capabilities of the ATHENA apparatus, allowed detailed studies of the pulsing behavior, which in turn gave information on the dependence of the antihydrogen production process on the positron temperature T. Our data are consistent with power law scaling T (-1.1+/-0.5) for the production rate in the high temperature regime from approximately 100 meV up to 1.5 eV. This is not in accord with the behavior accepted for conventional three-body recombination.     

Multipion systems in lattice QCD and the three-pion interaction

The ground-state energies of 2, 3, 4, and 5 pi(+)'s in a spatial volume V approximately (2.5 fm)(3) are computed with lattice QCD. By eliminating the leading contribution from three-pi(+) interactions, particular combinations of these n-pi(+) ground-state energies provide precise extractions of the pi(+)pi(+) scattering length in agreement with that obtained from calculations involving only two pi(+)'s. The three-pi(+) interaction can be isolated by forming other combinations of the n-pi(+) ground-state energies. We find a result that is consistent with a repulsive three-pi(+) interaction for m_(pi) less, similar352 MeV.     

Roper resonance—Its static and dynamic properties from single- and double-pion production

In most investigations the Roper resonance is sensed only very indirectly via complex partial wave analyses. We find indications for its excitation in the pp→npπ⁺ reaction, where some resonance-like structure is observed in the invariant nπ⁺ mass spectrum at with a width of 150 MeV. The values fit very favorably to the most recent phase shift results as well as to the observations at BES. In near-threshold two-pion production pp→ppπ⁰π⁰ the Roper excitation and its subsequent decay into Nππ is the only dominant process. There we find its decay into the Nσ channel as the dominating decay process — in favor of a monopole nature of the Roper excitation.