307 research outputs found

    Production and mixing of scalar mesons in ηc\eta_c and χc1\chi_{c1} decays

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    We briefly discuss how the chiral unitary approach in coupled channels and SU(3)SU(3) symmetry can be used to describe the production of f0(500)f_0(500), f0(980)f_0(980) and a0(980)a_0(980) in the χc1→ηπ+π−\chi_{c1} \to \eta \pi^+ \pi^- reaction, recently measured by the BESIII collaboration. In this reaction a very strong peak for the a0(980)a_0(980) can be seen in the ηπ\eta\pi invariant mass, while clear signals for the f0(500)f_0(500) and f0(980)f_0(980) appear in the one of π+π−\pi^+\pi^-. Next, we show the predictions made with the same model for the analogous decay ηc→ηπ+π−\eta_c \to \eta \pi^+ \pi^-, which could also be measured experimentally. We discuss the differences of these two reactions which are interesting to test the picture where these scalar mesons are dynamically generated from the interaction of pairs of pseudoscalars. Furthermore, we comment on a new recent work where the same model was used to study the a0(980)−f0(980)a_0(980) - f_0(980) mixing in the χc1→π0π0η\chi_{c1} \to \pi^0 \pi^0 \eta and χc1→π0π+π−\chi_{c1} \to \pi^0 \pi^+ \pi^- reactions, showing that quantitative agreement with the experimental measurement of this mixing, also performed by BESIII, can be obtained, revealing interesting aspects of the dynamics of this process and the importance of coupled channels.Comment: Talk presented at the XVII International Conference on Hadron Spectroscopy and Structure - Hadron2017, 25-29 September, 2017, University of Salamanca, Salamanca, Spain. arXiv admin note: substantial text overlap with arXiv:1707.0722

    Performance Evaluation of Homogeneous Charge Compression Ignition Combustion Engine â A Review

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    The development of HCCI combustion technology has been drawing a great deal of attention from researchers. This survey explains ongoing research methodologies and results. HCCI combustion, other than conventional combustion, is purely based on chemical kinetics. At present the automobile sector faces the problem of emissions and needs to develop clean technologies. However, HCCI operation still has issues such as ignition control, combustion phasing control, operating range control, cold start, and UHC (unburned hydrocarbon) and CO (carbon monoxide) emissions. The challenge is to overcome these problems without compromising other engine parameters and performance. For HCCI, the mixture preparation is especially important, while the compression ratio, IVC (inlet valve closure) timing, inlet pressure, inlet temperature and EGR play a very prominent role in controlling it. This paper will go through a detailed discussion of all the above conditions

    The gΣQΣQπg_{\Sigma_Q\Sigma_Q\pi} Coupling Constant via Light Cone QCD Sum Rules

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    Using the most general form of the interpolating currents, the coupling constants gΣbΣbπg_{\Sigma_b\Sigma_b\pi} and gΣcΣcπg_{\Sigma_c\Sigma_c\pi} are calculated within the light cone QCD sum rules approach. It is found that gΣcΣcπ=−8.0±1.7g_{{\Sigma_{c}\Sigma_{c}\pi}}=-8.0\pm1.7 and gΣbΣbπ=−11.0±2.1g_{{\Sigma_{b}\Sigma_{b}\pi}}=-11.0\pm2.1.Comment: 9 pages, 4 figure

    Botanical and Genetic Identification Followed by Investigation of Chemical Composition and Biological Activities on the Scabiosa atropurpurea L. Stem from Tunisian Flora

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    Scarce information about the phenolic composition of Scabiosa atropurpurea L. is available, and no carotenoid compounds have been reported thus far. In this study the phenolic and carotenoid composition of this plant was both investigated and associated bioactivities were evaluated. Aiming to obtain extracts and volatile fractions of known medicinal plants to valorize them in the pharmaceutical or food industries, two techniques of extraction and five solvents were used to determine the biologically active compounds. Gas chromatography coupled to flame ionization and mass spectrometry and liquid chromatography coupled to photodiode array and atmospheric pressure chemical ionization/electrospray ionization mass spectrometry highlighted the presence of 15 volatiles, 19 phenolic, and 24 natural pigments in Scabiosa atropurpurea L. stem samples; among them, the most abundant were 1,8-cineole, chlorogenic acid, cynaroside, and lutein. Bioactivity was assessed by a set of in vitro tests checking for antioxidant, antibacterial, antifungal, and allelopathic (against Brassica oleracea L. and Lens culinaris Medik) effects. Scabiosa atropurpurea L. stem extracts presented a considerable antioxidant, antibacterial, and allelopathic potential, with less antifungal effectiveness. These results indicate that the volatile fractions and extracts from S. atropurpurea L. stem could be considered as a good source of bioactive agents, with possible applications in food-related, agriculture, and pharmaceutical fields. Genetic investigations showed 97% of similarity with Scabiosa tschiliensis, also called Japanese Scabiosa

    The Bounds on the magnetic moment of the tau-neutrino via the process (e+e-)-->nunu(bar)gamma

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    Bounds on the anamolous magnetic moment of the tau neutrino are calculated through the reaction (e+e-)-->nunu(bar)gamma at the neutral boson pole and in the framework of an extended standard model, a left-right symmetric model and a superstring-inspired model which has one extra low-energy neutral gauge boson. The results are basedComment: 9 pages, 1 figure, 3 Table

    Double-wedged Wollaston-type polarimeter design and integration to RTT150-TFOSC; initial tests, calibration, and characteristics

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    © 2015, Springer Science+Business Media Dordrecht. Photometric and spectroscopic observation capabilities of 1.5-m Russian–Turkish Telescope RTT150 has been broadened with the integration of presented polarimeter. The well-known double-wedged Wollaston-type dual-beam technique was preferred and applied to design and produce it. The designed polarimeter was integrated into the telescope detector TFOSC, and called TFOSC-WP. Its capabilities and limitations were attempted to be determined by a number of observation sets. Non-polarized and strongly polarized stars were observed to determine its limitations as well as its linearity. An instrumental intrinsic polarization was determined for the 1 × 5 arcmin field of view in equatorial coordinate system, the systematic error of polarization degree as 0.2 %, and position angle as 1.9∘. These limitations and capabilities are denoted as good enough to satisfy telescopes’ present and future astrophysical space missions related to GAIA and SRG projects

    Do novel European Headache Federation criteria identify differences in migraine burden?: baseline data of an international real-life study on resistant and refractory migraine (REFINE)

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    Question. We evaluated if EHF criteria for resistant (RES) and refractory (REF) migraine identify patients with more severe migraine burden. Methods. We performed an observational, multi center, international study to compare baseline characteristics, comorbidities, and PROMs of non-resistant and non-refractory (NRNR) migraine, RES and REF individuals in the REFINE study. Results. We included 175 individuals with NRNR migraine, 133 (39.7%) with RES and 27 (8.0%) with REF. Individuals with RES and REF migraine as compared to those with NRNR reported higher monthly migraine days (median=8, IQR=5-14 vs. median=13, IQR=10- 17 and median=15, IQR=10-20; p≤0.001), months of chronification (median=24, IQR=12-72 vs. median=40, IQR=12-108 and median=60, IQR=18-96; p=0.044), monthly days of symptomatic drugs assumption (median=8, IQR=5-15 vs. median=12, IQR=9-20 and median=15, IQR=10-20; p≤0.001), medication overuse (19.4% vs. 45.9% and 40.7%; p≤0.001). They also had more comorbidities such as depression (18.3% vs. 31.1% and 44.4%; p=0.002) and anxiety (13.7% vs. 21.1% and 37%; p=0.009). In these groups, PROMs also revealed a higher presence of anxiety (p≤0.001) and depression (p≤0.001) symptoms and poorer sleep quality (p=0.006). Regarding specific perceptions about migraine, RES and REF individuals reported higher impact of migraine on daily life (p≤0.001) and work, household work, and social life (p≤0.001), along with a lower perception of the effectiveness of their ongoing treatment for migraine (p≤0.001), when compared to NRNR subjects (Table 1). Conclusion. RES and REF migraine is associated with relevant migraine burden considering migraine features, comorbidities and scores at several scales; the severe burdensome condition of RES and REF is confirmed by the median number of monthly migraine days and PROMs.info:eu-repo/semantics/publishedVersio
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