The Next Generation of Axion Helioscopes: The International Axion Observatory (IAXO)

The International Axion Observatory (IAXO) is a proposed 4th-generation axion helioscope with the primary physics research goal to search for solar axions via their Primakoff conversion into photons of 1 \u2013 10 keV energies in a strong magnetic field. IAXO will achieve a sensitivity to the axion-photon coupling ga\u3b3 down to a few 710 1212 GeV 121 for a wide range of axion masses up to 3c 0.25 eV. This is an improvement over the currently best (3rd generation) axion helioscope, the CERN Axion Solar Telescope (CAST), of about 5 orders of magnitude in signal strength, corresponding to a factor 3c 20 in the axion photon coupling. IAXO's sensitivity relies on the construction of a large superconducting 8-coil toroidal magnet of 20 m length optimized for axion research. Each of the eight 60 cm diameter magnet bores is equipped with x-ray optics focusing the signal photons into 3c 0.2 cm2 spots that are imaged by very low background x-ray detectors. The magnet will be built into a structure with elevation and azimuth drives that will allow solar tracking for 12 hours each day. This contribution is a summary of our papers [1], [2] and [3] and we refer to these for further details

Evolution of the longitudinal and azimuthal structure of the near-side jet peak in Pb-Pb collisions at 1asNN = 2.76 TeV

In two-particle angular correlation measurements, jets give rise to a near-side peak, formed by particles associated to a higher-pT trigger particle. Measurements of these correlations as a function of pseudorapidity ( \u3b7) and azimuthal ( \u3c6) differences are used to extract the centrality and pT dependence of the shape of the near-side peak in the pT range 1 < pT < 8 GeV/c in Pb-Pb and pp collisions at 1asNN = 2.76 TeV. A combined fit of the near-side peak and long-range correlations is applied to the data and the peak shape is quantified by the variance of the distributions. While the width of the peak in the \u3c6 direction is almost independent of centrality, a significant broadening in the \u3b7 direction is found from peripheral to central collisions. This feature is prominent for the low-pT region and vanishes above 4 GeV/c. The widths measured in peripheral collisions are equal to those in pp collisions in the \u3c6 direction and above 3 GeV/c in the \u3b7 direction. Furthermore, for the 10% most central collisions and 1 < pT,assoc < 2 GeV/c, 1 < pT,trig < 3 GeV/c, a departure from a Gaussian shape is found: a depletion develops around the center of the peak. The results are compared to A Multi-Phase Transport (AMPT) model simulation as well as other theoretical calculations indicating that the broadening and the development of the depletion are connected to the strength of radial and longitudinal flow

Centrality dependence of inclusive J/\u3c8 production in p-Pb collisions at 1asNN = 5.02 TeV

We present a measurement of inclusive J/\u3c8 production in p-Pb collisions at 1asNN = 5.02TeV as a function of the centrality of the collision, as estimated from the energy deposited in the Zero Degree Calorimeters. The measurement is performed with the ALICE detector down to zero transverse momentum, pT, in the backward ( 124.46 < ycms < 122.96) and forward (2.03 < ycms < 3.53) rapidity intervals in the dimuon decay channel and in the mid-rapidity region ( 121.37 < ycms < 0.43) in the dielectron decay channel. The backward and forward rapidity intervals correspond to the Pb-going and p-going direction, respectively. The pT-differential J/\u3c8 production cross section at backward and forward rapidity is measured for several centrality classes, together with the corresponding average pT and pT2 values. The nuclear modification factor is presented as a function of centrality for the three rapidity intervals, and as a function of pT for several centrality classes at backward and forward rapidity. At mid- and forward rapidity, the J/\u3c8 yield is suppressed up to 40% compared to that in pp interactions scaled by the number of binary collisions. The degree of suppression increases towards central p-Pb collisions at forward rapidity, and with decreasing pT of the J/\u3c8. At backward rapidity, the nuclear modification factor is compatible with unity within the total uncertainties, with an increasing trend from peripheral to central p-Pb collisions

Centrality dependence of high-pT D meson suppression in Pb-Pb collisions at 1asNN = 2.76 TeV

The nuclear modification factor, RAA, of the prompt charmed mesons D0, D+ and D 17+, and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass energy 1asNN = 2.76 TeV in two transverse momentum intervals, 5 < pT < 8GeV/c and 8 < pT < 16GeV/c, and in six collision centrality classes. The RAA shows a maximum suppression of a factor of 5\u20136 in the 10% most central collisions. The suppression and its centrality dependence are compatible within uncertainties with those of charged pions. A comparison with the RAA of non-prompt J/\u3c8 from B meson decays, measured by the CMS Collaboration, hints at a larger suppression of D mesons in the most central collisions

NOTEWORTHY COLLECTIONS

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Pathways systematically associated to Hirschsprung's disease.

Despite it has been reported that several loci are involved in Hirschsprung's disease, the molecular basis of the disease remains yet essentially unknown. The study of collective properties of modules of functionally-related genes provides an efficient and sensitive statistical framework that can overcome sample size limitations in the study of rare diseases. Here, we present the extension of a previous study of a Spanish series of HSCR trios to an international cohort of 162 HSCR trios to validate the generality of the underlying functional basis of the Hirschsprung's disease mechanisms previously found. The Pathway-Based Analysis (PBA) confirms a strong association of gene ontology (GO) modules related to signal transduction and its regulation, enteric nervous system (ENS) formation and other processes related to the disease. In addition, network analysis recovers sub-networks significantly associated to the disease, which contain genes related to the same functionalities, thus providing an independent validation of these findings. The functional profiles of association obtained for patients populations from different countries were compared to each other. While gene associations were different at each series, the main functional associations were identical in all the five populations. These observations would also explain the reported low reproducibility of associations of individual disease genes across populations

Results and perspectives of the solar axion search with the CAST experiment

The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be presented. Recent results obtained by the use of 3He as a buffer gas has allowed us to extend our sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV 64ma 64 0.64 eV. From the absence of an excess of x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of ga\u3b3 642.3 710 1210 GeV 121 at 95% C.L., the exact value depending on the pressure setting. CAST published results represent the best experimental limit on the photon couplings to axions and other similar exotic particles dubbed WISPs (Weakly Interacting Slim Particles) in the considered mass range and for the first time the limit enters the region favored by QCD axion models. Preliminary sensitivities for axion masses up to 1.16 eV will also be shown reaching mean upper limits on the axion-photon coupling of ga\u3b3 643.5 710 1210 GeV 121 at 95% C.L. Expected sensibilities for the extension of the CAST program up to 2014 will be presented. Moreover long term options for a new helioscope experiment will be evoked

Conceptual design of the International Axion Observatory (IAXO)

The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4\u20135 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few 7 10 1212 GeV 121 and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling gae with sensitivity \u2014 for the first time \u2014 to values of gae not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20 m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x-ray optics, able to focus the signal photons into ~ 0.2 cm2 spots that are imaged by ultra-low-background Micromegas x-ray detectors. The magnet is built into a structure with elevation and azimuth drives that will allow for solar tracking for ~ 12 h each day

Studies of J/\u3c8 production at forward rapidity in Pb\u2013Pb collisions at sNNsqrtsmathrmNN sqrts_mathrmNN = 5.02 TeV

The inclusive J/\u3c8 production in Pb\u2013Pb collisions at the center-of-mass energy per nucleon pair sNN 12 12 12 1a = 5.02 TeV, measured with the ALICE detector at the CERN LHC, is reported. The J/\u3c8 meson is reconstructed via the dimuon decay channel at forward rapidity (2.5 < y < 4) down to zero transverse momentum. The suppression of the J/\u3c8 yield in Pb\u2013Pb collisions with respect to binary-scaled pp collisions is quantified by the nuclear modification factor (RAA). The RAA at sNN 12 12 12 1a = 5.02 TeV is presented and compared with previous measurements at sNN 12 12 12 1a = 2.76 TeV as a function of the centrality of the collision, and of the J/\u3c8 transverse momentum and rapidity. The inclusive J/\u3c8 RAA shows a suppression increasing toward higher transverse momentum, with a steeper dependence for central collisions. The modification of the J/\u3c8 average transverse momentum and average squared transverse momentum is also studied. Comparisons with the results of models based on a transport equation and on statistical hadronization are carried out