43 research outputs found
Energy dependence of ϕ meson production at forward rapidity in pp collisions at the LHC
The production of mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region . Measurements of the differential cross section are presented as a function of the transverse momentum () at the center-of-mass energies , 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at and 13 TeV are also studied in several rapidity intervals as a function of , and as a function of rapidity in three intervals. A hardening of the -differential cross section with the collision energy is observed, while, for a given energy, spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing . The new results, complementing the published measurements at and 7 TeV, allow one to establish the energy dependence of meson production and to compare the measured cross sections with phenomenological models. None of the considered models manages to describe the evolution of the cross section with and rapidity at all the energies.publishedVersio
Production of omega mesons in pp collisions at s=7 TeV
The invariant differential cross section of inclusive omega (782) meson production at midrapidity (|y| pi+pi-pi 0 decay channel. The measured omega production cross section is compared to various calculations: PYTHIA 8.2 Monash 2013 describes the data, while PYTHIA 8.2 Tune 4C overestimates the data by about 50%. A recent NLO calculation, which includes a model describing the fragmentation of the whole vector-meson nonet, describes the data within uncertainties below 6 GeV/c, while it overestimates the data by up to 50% for higher pT. The omega/pi 0 ratio is in agreement with previous measurements at lower collision energies and the PYTHIA calculations. In addition, the measurement is compatible with transverse mass scaling within the measured pT range and the ratio is constant with C omega/pi 0=0.67 +/- 0.03(stat) +/- 0.04(sys) above a transverse momentum of 2.5 GeV/c.Peer reviewe
First measurement of coherent ρ0 photoproduction in ultra-peripheral Xe–Xe collisions at √sNN = 5.44 TeV
The first measurement of the coherent photoproduction of ρ0 vector mesons in ultra-peripheral Xe–Xe collisions at sNN=5.44 TeV is presented. This result, together with previous HERA γp data and γ–Pb measurements from ALICE, describes the atomic number (A) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hard scale. The cross section of the Xe+Xe→ρ0+Xe+Xe process, measured at midrapidity through the decay channel ρ0→π+π−, is found to be dσ/dy=131.5±5.6(stat.)−16.9+17.5(syst.) mb. The ratio of the continuum to resonant contributions for the production of pion pairs is also measured. In addition, the fraction of events accompanied by electromagnetic dissociation of either one or both colliding nuclei is reported. The dependence on A of cross section for the coherent ρ0 photoproduction at a centre-of-mass energy per nucleon of the γA system of WγA,n=65 GeV is found to be consistent with a power-law behaviour σ(γA→ρ0A)∝Aα with a slope α=0.96±0.02(syst.). This slope signals important shadowing effects, but it is still far from the behaviour expected in the black-disc limit.publishedVersio
ϒ production in p–Pb collisions at sNN=8.16 TeV
ϒproduction in p–Pbinteractions is studied at the centre-of-mass energy per nucleon–nucleon collision √sNN=8.16TeV with the ALICE detector at the CERN LHC. The measurement is performed reconstructing bottomonium resonances via their dimuon decay channel, in the centre-of-mass rapidity intervals 2.03 <3.53and −4.46 <−2.96, down to zero transverse momentum. In this work, results on the ϒ(1S) production cross section as a function of rapidity and transverse momentum are presented. The corresponding nuclear modification factor shows a suppression of the ϒ(1S) yields with respect to ppcollisions, both at forward and backward rapidity. This suppression is stronger in the low transverse momentum region and shows no significant dependence on the centrality of the interactions. Furthermore, the ϒ(2S) nuclear modification factor is evaluated, suggesting a suppression similar to that of the ϒ(1S). A first measurement of the ϒ(3S) has also been performed. Finally, results are compared with previous ALICE measurements in p–Pbcollisions at √sNN=5.02TeV and with theoretical calculations
Probing the chiral magnetic wave with charge-dependent flow measurements in Pb-Pb collisions at the LHC
The Chiral MagneticWave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotropic flow coefficients are studied in Pb-Pb collisions at center-of-mass energy per nucleon-nucleon collision v sNN = 5.02TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic (v2) and triangular (v3) flow coefficients of positively and negatively charged particles as a function of their event-wise normalized number difference, is reported for inclusive and identified particles. The slope rNorm 3 is found to be larger than zero and to have a magnitude similar to rNorm 2, thus pointing to a large background contribution for these measurements. Furthermore, rNorm 2 can be described by a blast wave model calculation that incorporates local charge conservation. In addition, using the event shape engineering technique yields a fraction of CMW (fCMW) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit for fCMW, and in the 10-60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level
Thieno[3,2‑<i>b</i>]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 1: High-Throughput Screening and Preliminary Exploration
Lysine specific demethylase
1 KDM1A (LSD1) regulates histone methylation
and it is increasingly recognized as a potential therapeutic target
in oncology. We report on a high-throughput screening campaign performed
on KDM1A/CoREST, using a time-resolved fluorescence resonance energy
transfer (TR-FRET) technology, to identify reversible inhibitors.
The screening led to 115 hits for which we determined biochemical
IC<sub>50</sub>, thus identifying four chemical series. After data
analysis, we have prioritized the chemical series of <i>N</i>-phenyl-4<i>H</i>-thieno[3, 2-<i>b</i>]pyrrole-5-carboxamide
for which we obtained X-ray structures of the most potent hit (compound <b>19</b>, IC<sub>50</sub> = 2.9 μM) in complex with the enzyme.
Initial expansion of this chemical class, both modifying core structure
and decorating benzamide moiety, was directed toward the definition
of the moieties responsible for the interaction with the enzyme. Preliminary
optimization led to compound <b>90</b>, which inhibited the
enzyme with a submicromolar IC<sub>50</sub> (0.162 μM), capable
of inhibiting the target in cells
Thieno[3,2‑<i>b</i>]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 2: Structure-Based Drug Design and Structure–Activity Relationship
The balance of methylation
levels at histone H3 lysine 4 (H3K4)
is regulated by KDM1A (LSD1). KDM1A is overexpressed in several tumor
types, thus representing an emerging target for the development of
novel cancer therapeutics. We have previously described (Part 1, DOI 10.1021.acs.jmedchem.6b01018) the identification
of thieno[3,2-<i>b</i>]pyrrole-5-carboxamides as novel reversible
inhibitors of KDM1A, whose preliminary exploration resulted in compound <b>2</b> with biochemical IC<sub>50</sub> = 160 nM. We now report
the structure-guided optimization of this chemical series based on
multiple ligand/KDM1A-CoRest cocrystal structures, which led to several
extremely potent inhibitors. In particular, compounds <b>46</b>, <b>49</b>, and <b>50</b> showed single-digit nanomolar
IC<sub>50</sub> values for in vitro inhibition of KDM1A, with high
selectivity in secondary assays. In THP-1 cells, these compounds transcriptionally
affected the expression of genes regulated by KDM1A such as CD14,
CD11b, and CD86. Moreover, <b>49</b> and <b>50</b> showed
a remarkable anticlonogenic cell growth effect on MLL-AF9 human leukemia
cells
The ecological transition of the extreme energy events experiment
The need for reducing the emission of gases, potentially contributing to the greenhouse effect and climate change, has impacted many fields, including scientific research. The Extreme Energy Event (EEE) collaboration started, already several years ago, a series of tests aiming at finding a more eco-friendly replacement for the gases used in the Multigap Resistive Plate Chambers (MRPCs) of its network.
These tests identified a promising binary gas mixture, and data taking has begun with a subset of the telescopes of the EEE network, making EEE the first experiment in the world completely implemented with MRPCs and operating with an eco-friendly gas mixture. Here the results of the tests and a preliminary comparison of the telescope performance measured with the standard (non eco-friendly) and the new eco-friendly gas mixtures are presented and discussed
First measurement of prompt and non-prompt D⁎+ vector meson spin alignment in pp collisions at s=13 TeV
This letter reports the first measurement of spin alignment, with respect to the helicity axis, for ⁎ vector mesons and their charge conjugates from charm-quark hadronisation (prompt) and from beauty-meson decays (non-prompt) in hadron collisions. The measurements were performed at midrapidity () as a function of transverse momentum () in proton–proton (pp) collisions collected by ALICE at the centre-of-mass energy . The diagonal spin density matrix element of ⁎ mesons was measured from the angular distribution of the ⁎ decay products, in the ⁎ rest frame, with respect to the ⁎ momentum direction in the pp centre of mass frame. The value for prompt ⁎ mesons is consistent with 1/3, which implies no spin alignment. However, for non-prompt ⁎ mesons an evidence of larger than 1/3 is found. The measured value of the spin density element is in the interval, which is consistent with a Pythia 8 Monte Carlo simulation coupled with the EvtGen package, which implements the helicity conservation in the decay of ⁎ meson from beauty mesons. In non-central heavy-ion collisions, the spin of the ⁎ mesons may be globally aligned with the direction of the initial angular momentum and magnetic field. Based on the results for pp collisions reported in this letter it is shown that alignment of non-prompt ⁎ mesons due to the helicity conservation coupled to the collective anisotropic expansion may mimic the signal of global spin alignment in heavy-ion collisions
Exclusive and dissociative J/ψ photoproduction, and exclusive dimuon production, in p-Pb collisions at sNN =8.16 TeV
The ALICE Collaboration reports three measurements in ultraperipheral proton-lead collisions at forward rapidity. The exclusive two-photon process γγ→μ+μ− and the exclusive photoproduction of J/ψ are studied. J/ψ photoproduction with proton dissociation is measured for the first time at a hadron collider. The cross section for the two-photon process of dimuons in the invariant mass range from 1 to 2.5 GeV/c2 agrees with leading-order quantum electrodynamics calculations. The exclusive and dissociative cross sections for J/ψ photoproductions are measured for photon-proton center-of-mass energies from 27 to 57 GeV. They are in good agreement with HERA results