929 research outputs found

    Approximate k-state solutions to the Dirac-Yukawa problem based on the spin and pseudospin symmetry

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    Using an approximation scheme to deal with the centrifugal (pseudo-centrifugal) term, we solve the Dirac equation with the screened Coulomb (Yukawa) potential for any arbitrary spin-orbit quantum number {\kappa}. Based on the spin and pseudospin symmetry, analytic bound state energy spectrum formulas and their corresponding upper- and lower-spinor components of two Dirac particles are obtained using a shortcut of the Nikiforov-Uvarov method. We find a wide range of permissible values for the spin symmetry constant C_{s} from the valence energy spectrum of particle and also for pseudospin symmetry constant C_{ps} from the hole energy spectrum of antiparticle. Further, we show that the present potential interaction becomes less (more) attractive for a long (short) range screening parameter {\alpha}. To remove the degeneracies in energy levels we consider the spin and pseudospin solution of Dirac equation for Yukawa potential plus a centrifugal-like term. A few special cases such as the exact spin (pseudospin) symmetry Dirac-Yukawa, the Yukawa plus centrifugal-like potentials, the limit when {\alpha} becomes zero (Coulomb potential field) and the non-relativistic limit of our solution are studied. The nonrelativistic solutions are compared with those obtained by other methods.Comment: 21 pages, 6 figure

    B7 Costimulation Molecules Encoded by Replication-Defective, vhs-Deficient HSV-1 Improve Vaccine-Induced Protection against Corneal Disease

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    Herpes simplex virus 1 (HSV-1) causes herpes stromal keratitis (HSK), a sight-threatening disease of the cornea for which no vaccine exists. A replication-defective, HSV-1 prototype vaccine bearing deletions in the genes encoding ICP8 and the virion host shutoff (vhs) protein reduces HSV-1 replication and disease in a mouse model of HSK. Here we demonstrate that combining deletion of ICP8 and vhs with virus-based expression of B7 costimulation molecules created a vaccine strain that enhanced T cell responses to HSV-1 compared with the ICP8−vhs− parental strain, and reduced the incidence of keratitis and acute infection of the nervous system after corneal challenge. Post-challenge T cell infiltration of the trigeminal ganglia and antigen-specific recall responses in local lymph nodes correlated with protection. Thus, B7 costimulation molecules expressed from the genome of a replication-defective, ICP8−vhs− virus enhance vaccine efficacy by further reducing HSK

    An Integrated Transcriptomic and Meta-Analysis of Hepatoma Cells Reveals Factors That Influence Susceptibility to HCV Infection

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    Hepatitis C virus (HCV) is a global problem. To better understand HCV infection researchers employ in vitro HCV cell-culture (HCVcc) systems that use Huh-7 derived hepatoma cells that are particularly permissive to HCV infection. A variety of hyper-permissive cells have been subcloned for this purpose. In addition, subclones of Huh-7 which have evolved resistance to HCV are available. However, the mechanisms of susceptibility or resistance to infection among these cells have not been fully determined. In order to elucidate mechanisms by which hepatoma cells are susceptible or resistant to HCV infection we performed genome-wide expression analyses of six Huh-7 derived cell cultures that have different levels of permissiveness to infection. A great number of genes, representing a wide spectrum of functions are differentially expressed between cells. To focus our investigation, we identify host proteins from HCV replicase complexes, perform gene expression analysis of three HCV infected cells and conduct a detailed analysis of differentially expressed host factors by integrating a variety of data sources. Our results demonstrate that changes relating to susceptibility to HCV infection in hepatoma cells are linked to the innate immune response, secreted signal peptides and host factors that have a role in virus entry and replication. This work identifies both known and novel host factors that may influence HCV infection. Our findings build upon current knowledge of the complex interplay between HCV and the host cell, which could aid development of new antiviral strategies

    50 Years of quantum chromodynamics – Introduction and Review

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    Synaptic integrative mechanisms for spatial cognition

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    Studies of η\eta and η\eta' production in pppp and ppPb collisions

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    The production of η\eta and η\eta' mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.025.02 and 13 TeV13~{\rm TeV}, and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16 TeV8.16~{\rm TeV}. The studies are performed in center-of-mass rapidity regions 2.5<yc.m.<3.52.5<y_{\rm c.m.}<3.5 (forward rapidity) and 4.0<yc.m.<3.0-4.0<y_{\rm c.m.}<-3.0 (backward rapidity) defined relative to the proton beam direction. The η\eta and η\eta' production cross sections are measured differentially as a function of transverse momentum for 1.5<pT<10 GeV1.5<p_{\rm T}<10~{\rm GeV} and 3<pT<10 GeV3<p_{\rm T}<10~{\rm GeV}, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for η\eta and η\eta' mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of η\eta mesons are also used to calculate η/π0\eta/\pi^0 cross section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as η\eta and η\eta' meson fragmentation.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb public pages

    Observation of Cabibbo-suppressed two-body hadronic decays and precision mass measurement of the Ωc0\Omega_{c}^{0} baryon

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    The first observation of the singly Cabibbo-suppressed Ωc0ΩK+\Omega_{c}^{0}\to\Omega^{-}K^{+} and Ωc0Ξπ+\Omega_{c}^{0}\to\Xi^{-}\pi^{+} decays is reported, using proton-proton collision data at a centre-of-mass energy of 13TeV13\,{\rm TeV}, corresponding to an integrated luminosity of 5.4fb15.4\,{\rm fb}^{-1}, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be B(Ωc0ΩK+)B(Ωc0Ωπ+)=0.0608±0.0051(stat)±0.0040(syst)\frac{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}K^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.0608\pm0.0051({\rm stat})\pm 0.0040({\rm syst}), B(Ωc0Ξπ+)B(Ωc0Ωπ+)=0.1581±0.0087(stat)±0.0043(syst)±0.0016(ext)\frac{\mathcal{B}(\Omega_{c}^{0}\to\Xi^{-}\pi^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.1581\pm0.0087({\rm stat})\pm0.0043({\rm syst})\pm0.0016({\rm ext}). In addition, using the Ωc0Ωπ+\Omega_{c}^{0}\to\Omega^{-}\pi^{+} decay channel, the Ωc0\Omega_{c}^{0} baryon mass is measured to be M(Ωc0)=2695.28±0.07(stat)±0.27(syst)±0.30(ext)MeV/c2M(\Omega_{c}^{0})=2695.28\pm0.07({\rm stat})\pm0.27({\rm syst})\pm0.30({\rm ext})\,{\rm MeV}/c^{2}, improving the precision of the previous world average by a factor of four.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-011.html (LHCb public pages

    Fraction of χc\chi_c decays in prompt J/ψJ/\psi production measured in pPb collisions at sNN=8.16\sqrt{s_{NN}}=8.16 TeV

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    The fraction of χc1\chi_{c1} and χc2\chi_{c2} decays in the prompt J/ψJ/\psi yield, Fχc=σχcJ/ψ/σJ/ψF_{\chi c}=\sigma_{\chi_c \to J/\psi}/\sigma_{J/\psi}, is measured by the LHCb detector in pPb collisions at sNN=8.16\sqrt{s_{NN}}=8.16 TeV. The study covers the forward (1.5<y<4.01.5<y^*<4.0) and backward (5.0<y<2.5-5.0<y^*<-2.5) rapidity regions, where yy^* is the J/ψJ/\psi rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples correspond to integrated luminosities of 13.6 ±\pm 0.3 nb1^{-1} and 20.8 ±\pm 0.5 nb1^{-1}, respectively. The result is presented as a function of the J/ψJ/\psi transverse momentum pT,J/ψp_{T,J/\psi} in the range 1<pT,J/ψ<20<p_{T, J/\psi}<20 GeV/cc. The FχcF_{\chi c} fraction at forward rapidity is compatible with the LHCb measurement performed in pppp collisions at s=7\sqrt{s}=7 TeV, whereas the result at backward rapidity is 2.4 σ\sigma larger than in the forward region for 1<pT,J/ψ<31<p_{T, J/\psi}<3 GeV/cc. The increase of FχcF_{\chi c} at low pT,J/ψp_{T, J/\psi} at backward rapidity is compatible with the suppression of the ψ\psi(2S) contribution to the prompt J/ψJ/\psi yield. The lack of in-medium dissociation of χc\chi_c states observed in this study sets an upper limit of 180 MeV on the free energy available in these pPb collisions to dissociate or inhibit charmonium state formation.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-028.html (LHCb public pages
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