Cross section normalization in proton-proton collisions at s\sqrt{s} = 2.76 TeV and 7 TeV, with ALICE at LHC

Measurements of the cross sections of the reference processes seen by the ALICE trigger system were obtained based on beam properties measured from van der Meer scans. The measurements are essential for absolute cross section determinations of physics processes. The paper focuses on instrumental and technical aspects of detectors and accelerators, including a description of the extraction of beam properties from the van der Meer scan. As a result, cross sections of reference processes seen by the ALICE trigger system are given for proton-proton collisions at two energies; $\sqrt{s}$=2.76 TeV and 7 TeV, together with systematic uncertainties originating from beam intensity measurements and other detector effects. Consistency checks were performed by comparing to data from other experiments in LHC.Comment: Quark Matter 2011 Conference Proceedings, 4 pages, 2 figure

Limits on Interactions between Weakly Interacting Massive Particles and Nucleons Obtained with NaI(Tl) crystal Detectors

Limits on the cross section for weakly interacting massive particles (WIMPs) scattering off nucleons in the NaI(Tl) detectors at the Yangyang Underground Laboratory are obtained with a 2967.4 kg*day data exposure. Nuclei recoiling are identified by the pulse shape of scintillating photon signals. Data are consistent with no nuclear recoil hypothesis, and 90% confidence level upper limits are set. These limits partially exclude the DAMA/LIBRA region of WIMP-sodium interaction with the same NaI(Tl) target detector. This 90% confidence level upper limit on WIMP-nucleon spin-independent cross section is 3.26*10^-4 pb for a WIMP mass at 10 GeV/c^2

On Heavy-Quark Free Energies, Entropies, Polyakov Loop, and AdS/QCD

In this paper we explore some of the features of a heavy quark-antiquark pair at finite temperature using a five-dimensional framework nowadays known as AdS/QCD. We shall show that the resulting behavior is consistent with our qualitative expectations of thermal gauge theory. Some of the results are in good agreement with the lattice data that provides additional evidence for the validity of the proposed model.Comment: 15 pages, 10 figures; v2: comments added, misprints correcte

The highly polarized open cluster Trumpler 27

We have carried out multicolor linear polarimetry (UBVRI) of the brightest stars in the area of the open cluster Trumpler 27. Our data show a high level of polarization in the stellar light with a considerable dispersion, from $P = 4$ to $P = 9.5$. The polarization vectors of the cluster members appear to be aligned. Foreground polarization was estimated from the data of some non-member objects, for which two different components were resolved: the first one associated with a dust cloud close to the Sun producing $P_{\lambda max}=1.3$ and $\theta=146$ degrees, and a second component, the main source of polarization for the cluster members, originated in another dust cloud, which polarizes the light in the direction of $\theta= 29.5$ degrees. From a detailed analysis, we found that the two components have associated values $E_{B-V} < 0.45$ for the first one, and $E_{B-V} > 0.75$ for the other. Due the difference in the orientation of both polarization vectors, almost 90 degrees (180 degrees at the Stokes representation), the first cloud ($\theta \sim 146$ degrees) depolarize the light strongly polarized by the second one ($\theta \sim 29.5$ degrees).Comment: 12 Pages, 6 Figures, 2 tables (9 Pages), accepted for publication in A

Properties of Exotic Matter for Heavy Ion Searches

We examine the properties of both forms of strange matter, small lumps of strange quark matter (strangelets) and of strange hadronic matter (Metastable Exotic Multihypernuclear Objects: MEMOs) and their relevance for present and future heavy ion searches. The strong and weak decays are discussed separately to distinguish between long-lived and short-lived candidates where the former ones are detectable in present heavy ion experiments while the latter ones in future heavy ion experiments, respectively. We find some long-lived strangelet candidates which are highly negatively charged with a mass to charge ratio like a anti deuteron (M/Z=-2) but masses of A=10 to 16. We predict also many short-lived candidates, both in quark and in hadronic form, which can be highly charged. Purely hyperonic nuclei are bound and have a negative charge while carrying a positive baryon number. We demonstrate also that multiply charmed exotics (charmlets) might be bound and can be produced at future heavy ion colliders.Comment: 10 pages, 4 figures, uses IOP style and epsf.sty, to be published in Journal of Physics, Proceedings of the International Symposium on Strangeness in Quark Matter 1997, April 14-18, Thera (Santorini), Hellas. Corrected typos, added comment about bag constant

Reconstructed Jets at RHIC

To precisely measure jets over a large background such as pile up in high luminosity p+p collisions at LHC, a new generation of jet reconstruction algorithms is developed. These algorithms are also applicable to reconstruct jets in the heavy ion environment where large event multiplicities are produced. Energy loss in the medium created in heavy ion collisions are already observed indirectly via inclusive hadron distributions and di-hadron correlations. Jets can be used to study this energy loss in detail with reduced biases. We review the latest results on jet-medium interactions as seen in A+A collisions at RHIC, focusing on the recent progress on jet reconstruction in heavy ion collisions.Comment: Proceedings for the 26th Winter Workshop on Nuclear Dynamic