OGLE-2012-BLG-0563Lb: a Saturn-mass planet around an M dwarf with the mass constrained by <i>Subaru</i> AO imaging

We report the discovery of a microlensing exoplanet OGLE-2012-BLG-0563Lb with the planet–star mass ratio of ~1 x 10-3. Intensive photometric observations of a high-magnification microlensing event allow us to detect a clear signal of the planet. Although no parallax signal is detected in the light curve, we instead succeed at detecting the flux from the host star in high-resolution JHK'-band images obtained by the Subaru/AO188 and Infrared Camera and Spectrograph instruments, allowing us to constrain the absolute physical parameters of the planetary system. With the help of spectroscopic information about the source star obtained during the high-magnification state by Bensby et al., we find that the lens system is located at 1.3-0.8+0.6 kpc from us, and consists of an M dwarf (0.34-0.20+0.12M⊙) orbited by a Saturn-mass planet (0.39-0.23+0.14MJup) at the projected separation of 0.74-0.42+0.26 AU (close model) or 4.3-2.5+1.5 AU (wide model). The probability of contamination in the host star's flux, which would reduce the masses by a factor of up to three, is estimated to be 17%. This possibility can be tested by future high-resolution imaging. We also estimate the (J-Ks) and (H-Ks) colors of the host star, which are marginally consistent with a low metallicity mid-to-early M dwarf, although further observations are required for the metallicity to be conclusive. This is the fifth sub-Jupiter-mass (0.2p/MJup< 1) microlensing planet around an M dwarf with the mass well constrained. The relatively rich harvest of sub-Jupiters around M dwarfs is contrasted with a possible paucity of ~1–2 Jupiter-mass planets around the same type of star, which can be explained by the planetary formation process in the core-accretion scheme

Multiplicity dependence of pion, kaon, proton and lambda production in p–Pb collisions at √sNN = 5.02 TeV

Inthis Letter, comprehensive results on π±,K±,K0S, p(pbar) and Λ(Λbar) production at mid-rapidity (0< yCMS < 0.5) in p–Pb collisions at √sNN = 5.02 TeV, measured by the ALICE detector at the LHC, are reported. The transverse momentum distributions exhibit a hardening as a function of event multiplicity, which is stronger for heavier particles. This behavior is similar to what has been observed in pp and Pb–Pb collisions at the LHC. The measured pT distributions are compared to d–Au, Au–Au and Pb–Pb results at lower energy and with predictions based on QCD-inspired and hydrodynamic models

Centrality dependence of the pseudorapidity density distribution for charged particles in Pb\u2013Pb collisions at 1asNN = 2.76 TeV

We present the first wide-range measurement of the charged-particle pseudorapidity density distribution, for different centralities (the 0\u20135%, 5\u201310%, 10\u201320%, and 20\u201330% most central events) in Pb\u2013Pb collisions at 1asNN = 2.76 TeV at the LHC. The measurement is performed using the full coverage of the ALICE detectors, 125.0 < \u3b7 < 5.5, and employing a special analysis technique based on collisions arising from LHC \u2018satellite\u2019 bunches. We present the pseudorapidity density as a function of the number of participating nucleons as well as an extrapolation to the total number of produced charged particles (Nch = 17 165 \ub1 772 for the 0\u20135% most central collisions). From the measured dNch/d\u3b7 distribution we derive the rapidity density distribution, dNch/dy, under simple assumptions. The rapidity density distribution is found to be significantly wider than the predictions of the Landau model. We assess the validity of longitudinal scaling by comparing to lower energy results from RHIC. Finally the mechanisms of the underlying particle production are discussed based on a comparison with various theoretical models