Fri·Nov 10, 2017Friday·November 10, 2017

1. 01*

   Formation of $\Sigma \pi$ pairs in nuclear captures of K${}^{-}$ mesons

   Raffaele Del Grande🇮🇹 · Kristian Piscicchia🇮🇹 · Slawomir Wycech

   The capture of K${}^{-}$ mesons on nucleons bound in nuclei offer a chance to study the $\Sigma \pi$ pairs below the kinematic threshold of the $\bar{\mathrm{K}}$N systems. Various hyperon-pion charged combination are presently under investigation by AMADEUS. These data allow to test both isospin 0 and 1 amplitudes giving the possibility to detect the structure of resonant $\Lambda$(1405) state. Contrasted against similar electro-production data, it is possible to detect changes of $\Lambda$(1405) in nuclear media. Expected spectra and their uncertainties are calculated.

   nucl-exnucl-thActa Phys.Polon.B(2017)·15 citations
2. 02*

   Structure of the nucleon's low-lying excitations

   Chen Chen🇧🇷 · Bruno El-Bennich🇧🇷 · Craig D. Roberts🇺🇸 · Sebastian M. Schmidt🇩🇪 · Jorge Segovia🇪🇸 · Shaolong Wan🇨🇳

   A continuum approach to the three valence-quark bound-state problem in quantum field theory is used to perform a comparative study of the four lightest $(I=1/2,J^P=1/2^{\pm })$ baryon isospin-doublets in order to elucidate their structural similarities and differences. Such analyses predict the presence of nonpointlike, electromagnetically-active quark-quark (diquark) correlations within all baryons; and in these doublets, isoscalar-scalar, isovector-pseudovector, isoscalar-pseudoscalar, and vector diquarks can all play a role. In the two lightest $(1/2,1/2^{+})$ doublets, however, scalar and pseudovector diquarks are overwhelmingly dominant. The associated rest-frame wave functions are largely $S$-wave in nature; and the first excited state in this $1/2^{+}$ channel has the appearance of a radial excitation of the ground state. The two lightest $(1/2,1/2^{-})$ doublets fit a different picture: accurate estimates of their masses are obtained by retaining only pseudovector diquarks; in their rest frames, the amplitudes describing their dressed-quark cores contain roughly equal fractions of even- and odd-parity diquarks; and the associated wave functions are predominantly $P$-wave in nature, but possess measurable $S$-wave components. Moreover, the first excited state in each negative-parity channel has little of the appearance of a radial excitation. In quantum field theory, all differences between positive- and negative-parity channels must owe to chiral symmetry breaking, which is overwhelmingly dynamical in the light-quark sector. Consequently, experiments that can validate the contrasts drawn herein between the structure of the four lightest $(1/2,1/2^{\pm })$ doublets will prove valuable in testing links between emergent mass generation and observable phenomena and, plausibly, thereby revealing dynamical features of confinement.

   ↳ nucl-thhep-lathep-phnucl-exPRD(2018)·69 citations
3. 03*

   Spectral analysis for the Majorana Demonstrator experiment

   L. Hehn🇺🇸 · N. Abgrall🇺🇸 · S. I. Alvis🇺🇸 · I. J. Arnquist🇺🇸 · F. T. Avignone III🇺🇸 · A. S. Barabash🇷🇺 · C. J. Barton🇺🇸 · F. E. Bertrand🇺🇸 · T. Bode🇩🇪 · A. W. Bradley🇺🇸 · V. Brudanin🇷🇺 · M. Busch🇬🇧 and 59 other authors

   The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a ton-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and ${}^{76}\text{Ge}$-enriched germanium detectors totaling 44.1 kg (29.7 kg enriched detectors), located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Data taken with this setup since summer 2015 at different construction stages of the experiment show a clear reduction of the observed background index around the ROI for $0\nu \beta \beta$-decay search due to improvements in shielding. We discuss the statistical approaches to search for a $0\nu \beta \beta$-signal and derive the physics sensitivity for an expected exposure of $10\text{kg}\cdot \text{y}$ from enriched detectors using a profile likelihood based hypothesis test in combination with toy Monte Carlo data.

   ↳ physics.ins-detnucl-exJ.Phys.Conf.Ser.(2020)·2 citations
4. 04*

   $T$-matrix Approach to Quark-Gluon Plasma

   Shuai Y.F. Liu🇺🇸 · Ralf Rapp🇺🇸

   A selfconsistent thermodynamic $T$-matrix approach is deployed to study the microscopic properties of the quark-gluon plasma (QGP), encompassing both light- and heavy-parton degrees of freedom in a unified framework. The starting point is a relativistic effective Hamiltonian with a universal color force. The input in-medium potential is quantitatively constrained by computing the heavy-quark (HQ) free energy from the static $T$-matrix and fitting it to pertinent lattice-QCD (lQCD) data. The corresponding $T$-matrix is then applied to compute the equation of state (EoS) of the QGP in a two-particle irreducible formalism including the full off-shell properties of the selfconsistent single-parton spectral functions and their two-body interaction. In particular, the skeleton diagram functional is fully resummed to account for emerging bound and scattering states as the critical temperature is approached from above. We find that the solution satisfying three sets of lQCD data (EoS, HQ free energy and quarkonium correlator ratios) is not unique. As limiting cases we discuss a weakly-coupled solution (WCS) which features color-potentials close to the free energy, relatively sharp quasiparticle spectral functions and weak hadronic resonances near $T_{\mathrm{c}}$, and a strongly-coupled solution (SCS) with a strong color potential (much larger than the free energy) resulting in broad non-quasiparticle parton spectral functions and strong hadronic resonance states which dominate the EoS when approaching $T_{\mathrm{c}}$.

   ↳ nucl-thcond-mat.quant-gashep-lathep-ph+1PRC(2018)·94 citations
5. 05*

   Longitudinal decorrelation measures of flow magnitude and event-plane angles in ultra-relativistic nuclear collisions

   Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱

   We discuss the forward-backward correlations of harmonic flow in Pb+Pb collisions at the CERN Large Hadron Collider (LHC), applying standard multibin measures, as well as proposed here new measures. We illustrate the methods with hydrodynamic model simulations based on event-by-event initial conditions from the wounded quark model with asymmetric rapidity emission profiles. Within the model we examine independently the event-plane angle and the flow magnitude decorrelations. We find specific hierarchy between various flow decorrelation measures and confirm certain factorization relations. We find qualitative agreement of the model and the data from the ATLAS and CMS Collaborations.

   ↳ nucl-thhep-phnucl-exPRC(2018)·57 citations
6. 06*

   Dynamical and many-body correlation effects in the kinetic energy spectra of isotopes produced in nuclear multifragmentation

   S.R. Souza🇧🇷 · R. Donangelo🇧🇷 · M.B. Tsang🇺🇸 · W.G. Lynch🇺🇸

   The properties of the kinetic energy spectra of light isotopes produced in the breakup of a nuclear source and during the deexcitation of its products are examined. The initial stage, at which the hot fragments are created, is modeled by the Statistical Multifragmentation Model, whereas the Weisskopf-Ewing evaporation treatment is adopted to describe the subsequent fragment deexcita- tion, as they follow their classical trajectories dictated by the Coulomb repulsion among them. The energy spectra obtained are compared to available experimental data. The influence of the fusion cross-section entering into the evaporation treatment is investigated and its influence on the qual- itative aspects of the energy spectra turns out to be small. Although these aspects can be fairly well described by the model, the underlying physics associated with the quantitative discrepancies remains to be understood.

   ↳ nucl-thnucl-exPRC(2018)·6 citations
7. 07*

   Recent results of search for solar axions using resonant absorption by ${}^{83}$Kr nuclei

   A.V. Derbin🇷🇺 · I.S. Drachnev🇷🇺 · A.M. Gangapshev🇷🇺 · Yu.M. Gavrilyuk🇷🇺 · V.V. Kazalov🇷🇺 · V.V.Kobychev · V.V. Kuzminov🇷🇺 · V.N. Muratova🇷🇺 · S.I. Panasenko · S.S. Ratkevich🇺🇦 · D.A. Tekueva🇷🇺 · E.V. Unzhakov🇷🇺 · S.P. Yakimenko🇷🇺

   A search for resonant absorption of the solar axion by ${}^{83}\mathrm{Kr}$ nuclei was performed using the proportional counter installed inside the low-background setup at the Baksan Neutrino Observatory. The obtained model independent upper limit on the combination of isoscalar and isovector axion-nucleon couplings $|g_3-g_0|\le 8.4\times 10^{-7}$ allowed us to set the new upper limit on the hadronic axion mass of $m_A\le 65$ eV (95\% C.L.) with the generally accepted values $S$=0.5 and $z$=0.56.

   ↳ hep-exhep-phnucl-exJ.Phys.Conf.Ser.(2017)·3 citations
8. 08*

   ALICE Overview

   Alessandro Grelli (for the ALICE Collaboration)🇳🇱

   An overview of the recent results obtained by the ALICE Collaboration from the analysis of the pp, p-Pb and Pb-Pb data samples collected during LHC run I and the first half of run II is presented.

   ↳ hep-exnucl-exEPJ Web Conf.(2018)·7 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.