On Quasibound N* Nuclei

The possibility for the existence of unstable bound states of the S11 nucleon resonance N$^*$(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N$^*$ interaction involving a pion and eta meson exchange, N$^*$-nucleus potentials for N*-$^3$He and N*-$^{24}$Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-$^3$He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N$^*$ $\pi$ and N N$^*$ $\eta$ vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with $\Gamma \sim$ 80 and 110 MeV for N*-$^3$He and N*-$^{24}$Mg respectively.Comment: Presented at the Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Cracow, Poland, June 2015; to be published in Acta Physica Polonica B (2016

Possible eta-mesic 3He states within the finite rank approximation

We extend the method of time delay proposed by Eisenbud and Wigner, to search for unstable states formed by eta mesons and the 3He nucleus. Using few body equations to describe eta-3He elastic scattering, we predict resonances and unstable bound states within different models of the eta-N interaction. The eta-3He states predicted within this novel approach are in agreement with the recent claim of the evidence of eta-mesic 3He made by the TAPS collaboration.Comment: 10 pages LaTex, 3 figure

Small eta-N scattering lengths favour eta-d and eta-alpha states

Unstable states of the eta meson and the 3He nucleus predicted using the time delay method were found to be in agreement with a recent claim of eta-mesic 3He states made by the TAPS collaboration. Here, we extend this method to a speculative study of the unstable states occurring in the eta-d and eta-4He elastic scattering. The T-matrix for eta-4He scattering is evaluated within the Finite Rank Approximation (FRA) of few body equations. For the evaluation of time delay in the eta-d case, we use a parameterization of an existing Faddeev calculation and compare the results with those obtained from FRA. With an eta-N scattering length, $a_{\eta N} = (0.42, 0.34)$ fm, we find an eta-d unstable bound state around -16 MeV, within the Faddeev calculation. A similar state within the FRA is found for a low value of $a_{\eta N}$, namely, $a_{\eta N} = (0.28, 0.19)$ fm. The existence of an eta-4He unstable bound state close to threshold is hinted by $a_{\eta N} = (0.28, 0.19)$ fm, but is ruled out by large scattering lengths.Comment: 21 pages, LaTex, 7 Figure

Evidence of Pentaquark States from K+ N Scattering Data?

Motivated by the recent experimental evidence of the exotic B = S = +1 baryonic state Theta(1540), we examine the older existing data on K+ N elastic scattering through the time delay method. We find positive peaks in time delay around 1.545 and 1.6 GeV in the D03 and P01 partial waves of K+ N scattering respectively, in agreement with experiments. We also find an indication of the J=3/2 Theta* spin-orbit partner to the Theta, in the P03 partial wave at 1.6 GeV. We discuss the pros and contras of these findings in support of the interpretation of these peaks as possible exotics.Comment: 10 pages, 4 figure

Comment on "Hadronic 3^3Heη\eta production near threshold"

Measurements of the differential and total cross sections for the $p d \to ^3$He $\eta$ reaction at five energies were recently reported [Phys. Rev. C {\bf 75}, 014004 (2007)] and comparisons with theoretical models were made. We point out that these comparisons involved a model based on ad hoc assumptions and hence the conclusions regarding the reaction mechanism as well as the role of the higher partial waves drawn in the above work are misleading. Revised conclusions based on better model calculations are presented

Expression of the Antisense-to-Latency Transcript Long Noncoding RNA in Kaposi's Sarcoma-Associated Herpesvirus

ABSTRACT The regulation of latency is central to herpesvirus biology. Recent transcriptome-wide surveys have uncovered evidence for promiscuous transcription across the entirety of the Kaposi's sarcoma-associated herpesvirus (KSHV) genome and postulated the existence of multiple viral long noncoding RNAs (lncRNAs). Next-generation sequencing studies are highly dependent on the specific experimental approach and particular algorithms of analysis and therefore benefit from independent confirmation of the results. The antisense-to-latency transcript (ALT) lncRNA was discovered by genome-tiling microarray (Chandriani et al., J Virol 86:7934–7942, 2010, https://doi.org/10.1128/JVI.00645-10 ). To characterize ALT in detail, we physically isolated this lncRNA by a strand-specific hybrid capture assay and then employed transcriptome sequencing and novel reverse transcription-PCR (RT-PCR) assays to distinguish all RNA species in the KSHV latency region. These methods confirm that ALT initiates at positions 120739/121012 and encodes a single splice site, which is shared with the 3′-coterminal K14-vGPCR/ORF74 mRNA, terminating at 130873 (GenBank accession number GQ994935 ), resulting in an ∼10,000-nucleotide transcript. No shorter ALT isoforms were identified. This study also identified a novel intron within the LANA 5′ untranslated region using a splice acceptor at 127888. In summary, ALT joins PAN/nut1/T1.1 as a bona fide lncRNA of KSHV with potentially important roles in viral gene regulation and pathogenesis. IMPORTANCE Increasing data support the importance of noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and lncRNAs, which have been shown to exert critical regulatory functions without coding for recognizable proteins. Defining the sequences of these ncRNAs is essential for future studies aiming to functionally characterize a specific ncRNA. Most lncRNA studies are highly dependent on high-throughput sequencing and bioinformatic analyses, few studies follow up on the initial predictions, and analyses are at times discordant. The manuscript characterizes one key viral lncRNA, ALT, by physically isolating ALT and by a sequencing-independent assay. It provides for a simple assay to monitor lncRNA expression in experimental and clinical samples. ALT is expressed antisense to the major viral latency transcripts encoding LANA as well as the viral miRNAs and thus has the potential to regulate this key part of the viral life cycle