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Nuclear Theory·nucl-th

Wednesday·September 27, 2017

13 papers—6 primary·7 cross-listed

All13Primary6Cross-lists7
  1. 07

    [Submitted on 25 Sept 2017] (cross-list from hep-ph)

    Dihadron fragmentation functions in the quark-jet model: Transversely polarized quarks

    Hrayr H. Matevosyan🇦🇺 · Aram Kotzinian🇦🇲 · Anthony W. Thomas🇦🇺

    Within the most recent extension of the quark-jet hadronization framework, we explore the transverse-polarization-dependent dihadron fragmentation functions (DiFFs) and of a quark into pairs. Monte Carlo (MC) simulations are employed to model polarized quark hadronization and calculate the corresponding number densities. These, in turn, are used to extract the Fourier cosine moments of the DiFFs and . A notable finding is that there are previously unnoticed apparent discrepancies between the definitions of the so-called interference DiFF (IFF) , entering the cross sections for two-hadron semi-inclusive electroproduction, and those involved in the production of two pairs of hadrons from back-to-back jets in electron-positron annihilation. This manuscript completes the studies of all four leading twist DiFFs for unpolarized hadron pairs within the quark-jet framework, following our previous work on the helicity-dependent DiFF .

    Comments:
    10 pages, 6 figures. V3: Updated to version published in PRD with minor revisions of the text
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1709.08643 [pdf]
    PRD(2018)·23 citations
  2. 08

    [Submitted on 25 Sept 2017] (cross-list from nucl-ex)

    On Nd, Sm and other unexplored 2 decay isotopes

    Francesco Nozzoli🇮🇹

    Nd is one of only four (over a total of 35 existing) 2 decay isotope candidates whose half-lives currently lack experimental limits. The activity of the Sm daughter nuclide allows placement of limits on the 2 decay using the Nd/Nd abundance ratio ( yr) or direct search for Sm with accelerator mass spectrometers ( yr). With a similar approach, a modest ( Gyr) first limit on half-lives for the other unexplored unstable isotopes and competitive limits (few yr) for Mo and Sn are also given. Finally, it is shown how the limit yr for the unexplored Sm decay may be obtained from the data of a GSO crystal scintillator.

    Comments:
    5 pages, 1 figure
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1709.08735 [pdf]
    PRC(2018)·7 citations
  3. 09

    [Submitted on 25 Sept 2017] (cross-list from hep-ph)

    A meson-baryon molecular interpretation for some excited baryons

    Glòria Montaña🇪🇸 · Albert Feijoo🇪🇸 · Àngels Ramos🇪🇸

    We explore the possibility that some of the five narrow resonances recently observed at LHCb could correspond to pentaquark states, structured as meson-baryon bound states or molecules. The interaction of the low-lying pseudoscalar mesons with the ground-state baryons in the charm , strangeness and isospin 0 sector is built from t-channel vector meson exchange, using effective Lagrangians. The resulting s-wave coupled-channel unitarized amplitudes show the presence of two structures with similar masses and widths to those of the observed and . The identification of these resonances with the meson-baryon bound states found in this work would also imply assigning the values for their spin-parity. An experimental determination of the spin-parity of the would help in disentangling its structure, as the quark-based models predict its spin-parity to be either or .

    Comments:
    9 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1709.08737 [pdf]
    EPJA(2018)·76 citations
  4. 10

    [Submitted on 26 Sept 2017] (cross-list from hep-ph)

    The Roper resonance: a genuine quark state or a dynamically generated structure?

    B. Golli🇸🇮 · H. Osmanović🇧🇦 · S. Širca🇸🇮 · A. Švarc🇭🇷

    In view of the recent results of lattice QCD simulation in the P11 partial wave that has found no clear signal for the three-quark Roper state we investigate a different mechanism for the formation of the Roper resonance in a coupled channel approach including the , and channels. We fix the pion-baryon vertices in the underlying quark model while the -wave sigma-baryon interaction is introduced phenomenologically with the coupling strength, the mass and the width of the meson as free parameters. The Laurent-Pietarinen expansion is used to extract the information about the -matrix pole. The Lippmann-Schwinger equation for the matrix with a separable kernel is solved to all orders. For sufficiently strong coupling the kernel becomes singular and a quasi-bound state emerges at around 1.4~GeV, dominated by the component and reflecting itself in a pole of the -matrix. The alternative mechanism involving a quark resonant state is added to the model and the interplay of the dynamically generated state and the three-quark resonant state is studied. It turns out that for the mass of the three-quark resonant state above 1.6~GeV the mass of the resonance is determined solely by the dynamically generated state, nonetheless, the inclusion of the three-quark resonant state is imperative to reproduce the experimental width and the modulus of the resonance pole.

    Comments:
    11 pages, 11 figures; two figures added with some minor modifications of the text. To be published in Phys. Rev. C
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1709.09025 [pdf]
    PRC(2018)·18 citations
  5. 11

    [Submitted on 26 Sept 2017] (cross-list from nucl-ex)

    Quarkonium-photoproduction prospects at a fixed-target experiment at the LHC (AFTER@LHC)

    L. Massacrier🇫🇷 · J.P. Lansberg🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱

    We report on the potentialities offered by a fixed-target experiment at the LHC using the proton and ion LHC beams (AFTER@LHC project) regarding the study of J/psi exclusive-photoproduction in pA and AA collisions. The foreseen usage of polarised targets (hydrogen, deuteron, helium) gives access to measurements of the Single-Transverse-Spin Asymmetries of this exclusive process, therefore allowing one to access the helicity-flip Generalised Parton Distribution (GPD) Eg. We detail the expected yields of photoproduced J/psi in proton-hydrogen and lead-hydrogen collisions and discuss the statistical uncertainties on the asymmetry measurement for one year of data taking at the LHC.

    Comments:
    proceeding of PHOTON 2017, Internation Conference on the Structure and the Interactions of the Photon, international workshop on Photon-Photon collisions, international workshop on high energy photon colliders
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1709.09044 [pdf]
    CERN Proc.(2018)·7 citations
  6. 12

    [Submitted on 26 Sept 2017] (cross-list from hep-ph)

    Note on X(3872) production at hadron colliders and its molecular structure

    Miguel Albaladejo🇪🇸 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Ulf-G. Meißner🇩🇪 · Juan Nieves🇪🇸 · Andreas Nogga🇩🇪 · Zhi Yang🇩🇪

    The production of the X(3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.

    Comments:
    5 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1709.09101 [pdf]
    CPC(2017)·58 citations
  7. 13

    [Submitted on 26 Sept 2017] (cross-list from astro-ph.HE)

    Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra

    J. Nättilä · M. C. Miller · A. W. Steiner · J. J. E. Kajava · V. F. Suleimanov · J. Poutanen

    Observations of thermonuclear X-ray bursts from accreting neutron stars (NSs) in low-mass X-ray binary systems can be used to constrain NS masses and radii. Most previous work of this type has set these constraints using Planck function fits as a proxy: both the models and the data are fit with diluted blackbody functions to yield normalizations and temperatures which are then compared against each other. Here, for the first time, we fit atmosphere models of X-ray bursting NSs directly to the observed spectra. We present a hierarchical Bayesian fitting framework that uses state-of-the-art X-ray bursting NS atmosphere models with realistic opacities and relativistic exact Compton scattering kernels as a model for the surface emission. We test our approach against synthetic data, and find that for data that are well-described by our model we can obtain robust radius, mass, distance, and composition measurements. We then apply our technique to Rossi X-ray Timing Explorer observations of five hard-state X-ray bursts from 4U 1702-429. Our joint fit to all five bursts shows that the theoretical atmosphere models describe the data well but there are still some unmodeled features in the spectrum corresponding to a relative error of 1-5% of the energy flux. After marginalizing over this intrinsic scatter, we find that at 68% credibility the circumferential radius of the NS in 4U 1702-429 is R = 12.4+-0.4 km, the gravitational mass is M=1.9+-0.3 Msun, the distance is 5.1 < D/kpc < 6.2, and the hydrogen mass fraction is X < 0.09.

    Comments:
    15 pages, 11 figures, submitted to A&A
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1709.09120 [pdf]
    Astron.Astrophys.(2017)·219 citations

Affiliations

first authorsco-authorsvia INSPIRE