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J/ψ Elliptic Flow in Pb-Pb Collisions at sNN=5.02 TeV
Acharya, S.,Adamová,, D.,Adolfsson, J.,Aggarwal, M. M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahn, S. U.,Aiola, S.,Akindinov, A.,Al-Turany, M.,Alam, S. N.,Albuquerque, D. S. D. American Physical Society 2017 Physical Review Letters Vol.119 No.24
<P>We report a precise measurement of the J/psi elliptic flow in Pb-Pb collisions at root s(NN) = 5.02 TeV with the ALICE detector at the LHC. The J/psi mesons are reconstructed at midrapidity (|y| < 0.9) in the dielectron decay channel and at forward rapidity (2.5 < y < 4.0) in the dimuon channel, both down to zero transverse momentum. At forward rapidity, the elliptic flow v(2) of the J/psi is studied as a function of the transverse momentum and centrality. A positive v(2) is observed in the transverse momentum range 2<p(T)<8GeV/c in the three centrality classes studied and confirms with higher statistics our earlier results at root s(NN) = 2.76 TeV in semicentral collisions. At midrapidity, the J/psi v(2) is investigated as a function of the transverse momentum in semicentral collisions and found to be in agreement with the measurements at forward rapidity. These results are compared to transport model calculations. The comparison supports the idea that at low p(T) the elliptic flow of the J/psi originates from the thermalization of charm quarks in the deconfined medium but suggests that additional mechanisms might be missing in the models.</P>
Acharya, S.,Adamová,, D.,Adhya, S.P.,Adler, A.,Adolfsson, J.,Aggarwal, M.M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahmad, S.,Ahn, S.U.,Aiola, S.,Akindinov, A.,Al-Turany, M.,Alam North-Holland Pub. Co 2019 Physics letters. Section B Vol.798 No.-
<P><B>Abstract</B></P> <P>The ALICE collaboration performed the first rapidity-differential measurement of coherent J / ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy <SUB> s NN </SUB> = 5.02 TeV. The J / ψ is detected via its dimuon decay in the forward rapidity region ( − 4.0 < y < − 2.5 ) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 μb<SUP>−1</SUP>. The cross section for coherent J / ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J / ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of <SUP> ψ ′ </SUP> to J / ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons.</P>
Measurement of an Excess in the Yield ofJ/ψat Very LowpTin Pb-Pb Collisions atsNN=2.76 TeV
Adam, J.,Adamová,, D.,Aggarwal, M. M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahn, S. U.,Aiola, S.,Akindinov, A.,Alam, S. N.,Aleksandrov, D.,Alessandro, B.,Alexandre, D.,Alfaro M American Physical Society 2016 Physical review letters Vol.116 No.22
<P>We report on the first measurement of an excess in the yield of J/psi at very low transverse momentum (pT < 0.3 GeV/c) in peripheral hadronic Pb-Pb collisions at root s(NN) = 2.76 TeV, performed by ALICE at the CERN LHC. Remarkably, the measured nuclear modification factor of J/psi in the rapidity range 2.5 < y < 4 reaches about 7 (2) in the p(T) range 0-0.3 GeV/c in the 70%-90% (50%-70%) centrality class. The J/psi production cross section associated with the observed excess is obtained under the hypothesis that coherent photoproduction of J/psi is the underlying physics mechanism. If confirmed, the observation of J/psi coherent photoproduction in Pb-Pb collisions at impact parameters smaller than twice the nuclear radius opens new theoretical and experimental challenges and opportunities. In particular, coherent photoproduction accompanying hadronic collisions may provide insight into the dynamics of photoproduction and nuclear reactions, as well as become a novel probe of the quark-gluon plasma.</P>
Acharya, S.,Adamová,, D.,Adolfsson, J.,Aggarwal, M.M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahn, S.U.,Aiola, S.,Akindinov, A.,Al-Turany, M.,Alam, S.N.,Albuquerque, D.S.D.,Aleks North-Holland Pub. Co 2018 Physics letters. Section B Vol.780 No.-
<P><B>Abstract</B></P> <P>We present a measurement of azimuthal correlations between inclusive J/<I>ψ</I> and charged hadrons in p–Pb collisions recorded with the ALICE detector at the CERN LHC. The J/<I>ψ</I> are reconstructed at forward (p-going, 2.03 < y < 3.53 ) and backward (Pb-going, − 4.46 < y < − 2.96 ) rapidity via their <SUP> μ + </SUP> <SUP> μ − </SUP> decay channel, while the charged hadrons are reconstructed at mid-rapidity ( | η | < 1.8 ). The correlations are expressed in terms of associated charged-hadron yields per J/<I>ψ</I> trigger. A rapidity gap of at least 1.5 units is required between the trigger J/<I>ψ</I> and the associated charged hadrons. Possible correlations due to collective effects are assessed by subtracting the associated per-trigger yields in the low-multiplicity collisions from those in the high-multiplicity collisions. After the subtraction, we observe a strong indication of remaining symmetric structures at Δ φ ≈ 0 and Δ φ ≈ π , similar to those previously found in two-particle correlations at middle and forward rapidity. The corresponding second-order Fourier coefficient ( <SUB> v 2 </SUB> ) in the transverse momentum interval between 3 and 6 GeV/<I>c</I> is found to be positive with a significance of about 5<I>σ</I>. The obtained results are similar to the J/<I>ψ</I> <SUB> v 2 </SUB> coefficients measured in Pb–Pb collisions at <SUB> s NN </SUB> = 5.02 TeV, suggesting a common mechanism at the origin of the J/<I>ψ</I> <SUB> v 2 </SUB> .</P>
Observation of Exclusive Charmonium Production andγγ→μ+μ−inpp¯Collisions ats=1.96 TeV
Aaltonen, T.,Adelman, J.,Akimoto, T.,Albrow, M. G.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashm American Physical Society 2009 Physical Review Letters Vol.102 No.24
<P>In CDF we have observed the reactions p + p[over] --> p + X + p[over], with X being a centrally produced J/psi, psi(2S), or chi_{c0}, and gammagamma-->micro;{+}micro;{-} in pp[over] collisions at sqrt[s] = 1.96 TeV. The event signature requires two oppositely charged central muons, and either no other particles or one additional photon detected. Exclusive vector meson production is as expected for elastic photoproduction, gamma + p --> J/psi(psi(2S)) + p, observed here for the first time in hadron-hadron collisions. We also observe exclusive chi_{c0} --> J/psi + gamma. The cross sections dsigma/dy|_{y = 0} for J/psi, psi(2S), and chi_{c0} are 3.92 +/- 0.25(stat) +/- 0.52(syst) nb, 0.53 +/- 0.09(stat) +/- 0.10(syst) nb, and 76 +/- 10(stat) +/- 10(syst) nb, respectively, and the continuum is consistent with QED. We put an upper limit on the cross section for Odderon exchange in exclusive J/psi production.</P>
Jä,ger, K.,Bartó,k, T.,Ö,rdö,g, V.,Barnabá,s, B. Elsevier 2010 South African journal of botany : official journal Vol.76 No.3
<P><B>Abstract</B></P><P>This is the first report on the beneficial effect of microalgal and cyanobacterial biomass on anther cultures of maize (<I>Zea mays</I> L.). Investigations were made on the cytokinin- and auxin-like activity and content of terrestrial and fresh-water living microalgal and cyanobacterial strains. The influence of media supplemented with biomass from four selected strains on the anther induction, the frequency of microspore-derived embryo-like structures, and regeneration capacity in anther cultures of maize was also studied. The addition of cyanobacterial and microalgal biomass to the induction and regeneration media in concentrations of 1 or 2g/L improved the androgenic response, and was able to reduce the quantity of the synthetic auxin 2,4-dichlorophenoxy-acetic acid (2,4-D) required, or replace it completely.</P>
Adriá,n-Martí,nez, S.,Albert, A.,André,, M.,Anton, G.,Ardid, M.,Aubert, J.-J.,Baret, B.,Barrios-Martí,, J.,Basa, S.,Bertin, V.,Biagi, S.,Bormuth, R.,Bouwhuis, M. C.,Bruijn, R. American Astronomical Society 2016 The Astrophysical journal Vol.823 No.1
<P>We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E-2.5 and E-2 power-law spectra with different energy cut-offs.</P>
Inclusive J/<i>ψ</i> production in Xe–Xe collisions at <sub> s NN </sub> = 5.44 TeV
Acharya, S.,Acosta, F.T.-.,Adamová,, D.,Adolfsson, J.,Aggarwal, M.M.,Aglieri Rinella, G.,Agnello, M.,Agrawal, N.,Ahammed, Z.,Ahn, S.U.,Aiola, S.,Akindinov, A.,Al-Turany, M.,Alam, S.N.,Albuquerqu North-Holland Pub. Co 2018 Physics letters. Section B Vol.785 No.-
<P><B>Abstract</B></P> <P>Inclusive J/<I>ψ</I> production is studied in Xe–Xe interactions at a centre-of-mass energy per nucleon pair of <SUB> s NN </SUB> = 5.44 TeV, using the ALICE detector at the CERN LHC. The J/<I>ψ</I> meson is reconstructed via its decay into a muon pair, in the centre-of-mass rapidity interval 2.5 < y < 4 and down to zero transverse momentum. In this Letter, the nuclear modification factors <SUB> R AA </SUB> for inclusive J/<I>ψ</I>, measured in the centrality range 0–90% as well as in the centrality intervals 0–20% and 20–90% are presented. The <SUB> R AA </SUB> values are compared to previously published results for Pb–Pb collisions at <SUB> s NN </SUB> = 5.02 TeV and to the calculation of a transport model. A good agreement is found between Xe–Xe and Pb–Pb results as well as between data and the model.</P>
Ferreira, Má,rio F S,Castro-Camus, Enrique,Ottaway, David J,Ló,pez-Higuera, José,Miguel,Feng, Xian,Jin, Wei,Jeong, Yoonchan,Picqué,, Nathalie,Tong, Limin,Reinhard, Bjö,rn M IOP 2017 Journal of optics Vol.19 No.8
<P>Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light−matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers. Several other sections are dedicated to micro- and nano-engineered sensors, including whispering-gallery mode and plasmonic sensors. The uses of optical sensors in chemical, biological and biomedical areas are described in other sections. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed. Advances in science and technology required to meet challenges faced in each of these areas are addressed, together with suggestions on how the field could evolve in the near future.</P>