Predição da solubilidade de sólidos em CO2 supercrítico utilizando o modelo COSMO-SAC-Phi

A solubilidade de sólidos em dióxido de carbono supercrítico é uma informação importante para o projeto e otimização de processos nas indústrias alimentícia, farmacêutica e têxtil. O objetivo deste trabalho é investigar sistematicamente a precisão do modelo COSMO-SAC-Phi (CSP) em prever a solubilidade de sólidos em dióxido de carbono supercrítico. Os resultados obtidos através dos modelos PR + COSMOSAC EOS (PRCS), PSRK e Soave Redlich Kwong com a função alfa de Mathias Copeman com a clássica regra de mistura de Van der Waals (SRK-MC + vdW) foram comparados com o obtido através do modelo CSP. A solubilidade de 99 sólidos foi examinada. Uma grande variedade de compostos são considerados: ácidos alifáticos, álcoois alifáticos, hidrocarbonetos aromáticos, ácidos aromáticos, álcoois aromáticos, esteroides, estatinas e compostos aromáticos contendo átomos de nitrogênio, halogênio e/ou enxofre. A maioria destes compostos possuem moléculas semelhantes a fármacos. Um total de 2.450 pontos experimentais, cobrindo uma faixa de pressão de 45-500 bar e uma faixa de temperatura de 298-473 K, foram coletados para comparação com os resultados calculados. O banco de dados preditos para compostos puros Mol-Instincts foi usado para obter a pressão de saturação e o volume do líquido à pressão atmosfé- rica dos compostos estudados. A equação de estado CSP foi capaz de correlacionar os dados de pressão de saturação e volume do líquido com desvios médios de 5,32 % e 1,40 %, respectivamente. Com apenas dados de compostos puros, o CSP pôde predizer o equilíbrio sólido–fluido supercrítico das misturas. Quando a solubilidade calculada é comparada com dados experimentais, o desvio logarítmico médio da fração molar (ALDy) foi de 0,46 e 0,51 para as versões CSP (2021) e CSP (2019), respectivamente. Comparado aos modelos PSRK, PRCS e SRK-MC+vdW, a equação CSP (2021) teve um desempenho 27 %, 48 % e 64 % melhor, respectivamente, em termos de ALDy médio. Boas predições do ponto de cruzamento das isotermas de solubilidade foram também observadas. Isso indica que o modelo CSP pode fornecer uma primeira estimativa útil para a solubilidade, especialmente quando não há dados experimentais disponíveis.The solubility of solids in supercritical carbon dioxide is an important information for the design and optimization of processes in food, pharmaceutical and textile industries. The aim of this work is to systematically investigate the accuracy of COSMOSAC-Phi (CSP) model in predicting the solubility of solids in supercritical carbon dioxide. The results obtained through the PR + COSMOSAC EOS (PRCS), PSRK and Soave Redlich Kwong models with Mathias Copeman alpha function using the classic Van der Waals mixing rule (SRK-MC + vdW) were compared with those obtained from CSP model. The solubility of 99 solids was examined. A wide variety of compounds are considered, such as aliphatic acids, aliphatic alcohols, aromatic hydrocarbons, aromatic acids, aromatic alcohols, steroids, statins and aromatic compounds containing nitrogen, halogen and/or sulfur atoms, most of them are drug-like molecules. A total of 2450 experimental points covering a pressure range of 45-500 bar and a temperature range of 298-473 K obtained from the literature were compared with the calculated results. The Mol-Instincts database of predicted data from pure compounds was used to obtain the saturation pressure and the liquid volume at atmospheric pressure of the solids. The CSP equation of state was able to correlate the saturation pressure and the liquid volume at atmospheric pressure of the pure substances with average deviations of 5.32 % and 1.40 %, respectively. With only pure compound data, CSP could predict the behavior in mixture. When the calculated solubility is compared with experimental data, the average logarithmic deviation in molar fraction (ALDy) was 0.46 and 0.51 for the CSP (2021) and CSP (2019) versions, respectively. Compared to PSRK, PRCS and SRK-MC+vdW, the CSP (2021) model performed 27 %, 48 % and 64 % better, respectively, in terms of average ALDy. Good predictions of the crossover point of solubility isotherms were also observed. This indicates that the CSP model can provide a useful first estimate for solubility, especially when experimental data are not available

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Search for dark matter in events with a leptoquark and missing transverse momentum in proton-proton collisions at 13 TeV

A search is presented for dark matter in proton-proton collisions at a center-of-mass energy of root s= 13 TeV using events with at least one high transverse momentum (p(T)) muon, at least one high-p(T) jet, and large missing transverse momentum. The data were collected with the CMS detector at the CERN LHC in 2016 and 2017, and correspond to an integrated luminosity of 77.4 fb(-1). In the examined scenario, a pair of scalar leptoquarks is assumed to be produced. One leptoquark decays to a muon and a jet while the other decays to dark matter and low-p(T) standard model particles. The signature for signal events would be significant missing transverse momentum from the dark matter in conjunction with a peak at the leptoquark mass in the invariant mass distribution of the highest p(T) muon and jet. The data are observed to be consistent with the background predicted by the standard model. For the first benchmark scenario considered, dark matter masses up to 500 GeV are excluded for leptoquark masses m(LQ) approximate to 1400 GeV, and up to 300 GeV for m(LQ) approximate to 1500 GeV. For the second benchmark scenario, dark matter masses up to 600 GeV are excluded for m(LQ) approximate to 1400 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s\sqrt s = 13 TeV

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s}$ = 7 TeV, as well as with theoretical predictions.[graphic not available: see fulltext]Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s} =$ 7 TeV, as well as with theoretical predictions

Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV

A search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

Studies of Beauty Suppression via Nonprompt D-0 Mesons in Pb-Pb Collisions at root s(NN)=5.02 TeV

The transverse momentum spectra of D-0 mesons from b hadron decays are measured at midrapidity (vertical bar y vertical bar D-0 yield is found to be suppressed in the measured p(T) range from 2 to 100 GeV/c as compared to pp collisions. The suppression is weaker than that of prompt D-0 mesons and charged hadrons for p(T) around 10 GeV/c. While theoretical calculations incorporating partonic energy loss in the quark-gluon plasma can successfully describe the measured B -> D-0 suppression at higher p(T), the data show an indication of larger suppression than the model predictions in the range of 2 <p(T) <5 GeV/c.Peer reviewe