Measurement of quarkonium production at forward rapidity in pp collisions at √s=7 TeV

The inclusive production cross sections at forward rapidity of J/ψ , ψ(2S) , Υ (1S) and Υ (2S) are measured in pp collisions at s√=7 TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.35 pb‾¹ . Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ+μ− invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pT and rapidity y , over the ranges 0<pT<20 GeV/c for J/ψ , 0<pT<12 GeV/c for all other resonances and for \(2.5 . The measured cross sections integrated over pT and y , and assuming unpolarized quarkonia, are: σJ/ψ=6.69±0.04±0.63 μ b, σψ(2S)=1.13±0.07±0.19 μ b, σΥ(1S)=54.2±5.0±6.7 nb and σΥ(2S)=18.4±3.7±2.9 nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models

The Behavior, onḂ0,11, of an Oscillatory Integral with Polynomial Phase Function

AbstractWe study the convolution oscillatory singular integral operatorTf=p.v.Ω∗f, with Ω(x)=eiq(x)K(x), whereqis a real-valued polynomial of a real variable, of degreed≥2, andKis a Calderón–Zygmund-type kernel. We prove that this operator extends to an operator that maps the Besov spaceḂ0,11into the Hardy-type spaceH10

Transverse momentum dependence of inclusive primary charged-particle production in p–Pb collisions at √sNN=5.02 TeV

The transverse momentum ( pT ) distribution of primary charged particles is measured at midrapidity in minimum-bias p–Pb collisions at sNN−−−√=5.02 TeV with the ALICE detector at the LHC in the range \(0.15 GeV/ c . The spectra are compared to the expectation based on binary collision scaling of particle production in pp collisions, leading to a nuclear modification factor consistent with unity for pT larger than 2 GeV/ c , with a weak indication of a Cronin-like enhancement for pT around 4 GeV/c . The measurement is compared to theoretical calculations and to data in Pb–Pb collisions at sNN−−−√=2.76 TeV

Dehydroepiandrosterone sulfate mediates activation of transcription factors CREB and ATF-1 via a Gα11-coupled receptor in the spermatogenic cell line GC-2

AbstractDehydroepiandrosterone sulfate (DHEAS) is a circulating steroid produced in the adrenal cortex, brain, and gonads. Whereas a series of investigations attest to neuroprotective effects of the steroid in the brain, surprisingly little is known about the physiological effects of DHEAS on cells of the reproductive system. Here we demonstrate that DHEAS acting on the spermatogenic cell line GC-2 induces a time- and concentration-dependent phosphorylation of c-Src and Erk1/2 and activates the transcription factors activating transforming factor-1 (ATF-1) and cyclic AMP-responsive element binding protein (CREB). These actions are consistent with the non-classical signaling pathway of testosterone and suggest that DHEAS is a pro-androgen that is converted into testosterone in order to exert its biological activity. The fact, however, that steroid sulfatase mRNA was not detected in the GC-2 cells and the clear demonstration of DHEAS-induced activation of Erk1/2, ATF-1 and CREB after silencing the androgen receptor by small interfering RNA (siRNA) clearly contradict this assumption and make it appear unlikely that DHEAS has to be converted in the cytosol into a different steroid in order to activate the kinases and transcription factors mentioned. Instead, it is likely that the DHEAS-induced signaling is mediated through the interaction of the steroid with a membrane-bound G-protein-coupled receptor, since silencing of Guanine nucleotide-binding protein subunit alpha-11 (Gnα11) leads to the abolition of the DHEAS-induced stimulation of Erk1/2, ATF-1, and CREB. The investigation presented here shows a hormone-like activity of DHEAS on a spermatogenic cell line. Since DHEAS is produced in male and female reproductive organs, these findings could help to define new roles for DHEAS in the physiology of reproduction

Measurement of charm and beauty production at central rapidity versus charged-particle multiplicity in proton-proton collisions at s\sqrt{s} = 7 TeV

Prompt D meson and non-prompt J/$\psi$ yields are studied as a function of the multiplicity of charged particles produced in inelastic proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The results are reported as a ratio between yields in a given multiplicity interval normalised to the multiplicity-integrated ones (relative yields). They are shown as a function of the multiplicity of charged particles normalised to the average value for inelastic collisions (relative charged-particle multiplicity). D\)^0\), D\)^+\) and D\)^{*+}\) mesons are measured in five $p_{\rm T}$ intervals from 1 to 20 GeV/$c$ and for $|y|1.3$ GeV/$c$ and $|y|0$, The fraction of non-prompt J/$\psi$ in the inclusive J/$\psi$ yields shows no dependence on the charged-particle multiplicity at central rapidity. Charm and beauty hadron relative yields exhibit a similar increase with increasing charged-particle multiplicity. The measurements are compared to PYTHIA 8, EPOS 3 and percolation calculations.publishedVersio

Charmonium and e+e−e^+e^- pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV

The ALICE Collaboration at the LHC has measured the $J/\psi$ and $\psi$' photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The charmonium is identified via its leptonic decay 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 23 ${\mu}b^{-1}$, The cross section for coherent and incoherent $J/\psi$ production in the rapidity interval -0.9 < y < 0.9, are $d\sigma_{J/\psi}^{coh}/dy = 2.38^{+0.34}_{-0.24}(sta+sys)$ mb and $d\sigma_{J/\psi}^{inc}/dy = 0.98^{+0.19}_{-0.17}(sta+sys)$ mb, respectively. The results are compared to theoretical models for $J/\psi$ production and the coherent cross section is found to be in good agreement with those models which include nuclear gluon shadowing consistent with EPS09 parametrization. In addition the cross section for the process $\gamma\gamma \to e^+e^-$ has been measured and found to be in agreement with the STARLIGHT Monte Carlo predictions.publishedVersio

Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC

The average transverse momentum versus the charged-particle multiplicity $N_{ch}$ was measured in p-Pb collisions at a collision energy per nucleon-nucleon pair $\sqrt{s_{NN}}$ = 5.02 TeV and in pp collisions at collision energies of $\sqrt{s}$ = 0.9, 2.76, and 7 Tev in the kinematic range 0.15 with $N_{ch}$ is observed, which is much stronger than that measured in Pb-Pb collisions. For pp collisions, this could be attributed, within a model of hadronizing strings, to multiple-parton interactions and to a final-state color reconnection mechanism. The data in p-Pb and Pb-Pb collisions cannot be described by an incoherent superposition of nucleon-nucleon collisions and pose a challenge to most of the event generators.publishedVersio

Energy dependence of the transverse momentum distributions of charged particles in pp collisions measured by ALICE

Differential cross sections of charged particles in inelastic pp collisions as a function of $p_T$ have been measured at $\sqrt{s}$ = 0.9, 2.76 and 7 TeV at the LHC. The $p_T$ spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual $\sqrt{s}$ cannot be described by NLO-pQCD, the relative increase of cross section with $\sqrt{s}$ is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at $\sqrt{s}$ = 2.76 and 5.02 TeV up to $p_T$ = 50 GeV/c as required for the calculation of the nuclear modification factor in nucleus-nucleus and proton-nucleus collisions.publishedVersio

Mid-rapidity anti-baryon to baryon ratios in pp collisions at s\sqrt{s} = 0.9, 2.76 and 7 TeV measured by ALICE

The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for anti-proton/proton, anti-$\Lambda/\Lambda$, anti-$\Xi^{+}/\Xi^{-}$ and anti-$\Omega^{+}/\Omega^{-}$ in pp collisions at $\sqrt{s}$ = 0.9, 2.76 and 7 TeV, measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING/B, that are used to model the particle production in pp collisions. The energy dependence of anti-proton/proton, anti-$\Lambda/\Lambda$, anti-$\Xi^{+}/\Xi^{-}$ and anti-$\Omega^{+}/\Omega^{-}$, reaching values compatible with unity for $\sqrt{s}$ = 7 TeV, complement the earlier anti-proton/proton measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of $\alpha_J$ ≈ 0.5, which are suppressed with increasing rapidity interval $\Delta y$, Any significant contribution of an exchange not suppressed at large $\Delta y$ (reached at LHC energies) is disfavoured.publishedVersio

Jet shapes in pp and Pb–Pb collisions at ALICE

The aim of this work is to explore possible medium modifications to the substructure of inclusive charged jets in Pb-Pb relative to proton-proton collisions by measuring a set of jet shapes. The set of shapes includes the radial moment, g, and the momentum dispersion pTD. They provide complementary information on the fragmentation and can help to discriminate between two different scenarios: intra-jet broadening or collimation as a result of jet quenching. The shapes are measured in Pb–Pb collisions at √sNN = 2.76 TeV with a constituent cutoff of 0.15 GeV/c and jet resolution R = 0.2. New techniques for background subtraction are applied and a two-dimensional unfolding is performed to correct the shapes to particle level. The corrected jet shapes for jet pT 40 ≤ pT,jet ≤ 60 GeV/c are presented and discussed. The observed jet shape modifications suggest that the in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by a PYTHIA calculation. The PYTHIA calculation is validated with proton-proton data at 7 TeV.publishedVersio