Nuclear Theory·nucl-th

Tuesday·October 27, 2015

17 papers—9 primary·8 cross-listed

10
R-mode astronomy
Kostas D. Kokkotas🇩🇪 · Kai Schwenzer🇩🇪
Next generation gravitational wave detectors will start taking data in the near future. Here we discuss the chances to detect the continuous emission from r-mode oscillations in compact stars and study which properties of compact stars we can infer from such novel data. In particular we show that the combination of the gravitational wave data with electromagnetic multi-messenger observations could give us detailed insight into compact star properties, ranging from precise mass-radius measurements to the determination of the equation of state and the phase structure of dense matter.
↳ gr-qcastro-ph.HEastro-ph.SRnucl-thEPJA(2016)·35 citations
11
Coupled-Channel Model for $K ˉ N$ Scattering in the Resonant Region
C. Fernandez-Ramirez🇺🇸 · I. V. Danilkin🇺🇸 · D. M. Manley🇺🇸 · V. Mathieu🇺🇸 · A. P. Szczepaniak🇺🇸
We present a unitary multichannel model for $K ˉ N$ scattering in the resonance region that fulfills unitarity. It has the correct analytical properties for the amplitudes once they are extended to the complex- $s$ plane and the partial waves have the right threshold behavior. To determine the parameters of the model, we have fitted single-energy partial waves up to $J = 7/2$ and up to 2.15 GeV of energy in the center-of-mass reference frame obtaining the poles of the $Λ^{*}$ and $Σ^{*}$ resonances, which are compared to previous analyses. We provide the most comprehensive picture of the $S = - 1$ hyperon spectrum to date. Important differences are found between the available analyses making the gathering of further experimental information on $K ˉ N$ scattering mandatory to make progress in the assessment of the hyperon spectrum.
↳ hep-phnucl-thPRD(2016)·72 citations
12
Finite-temperature phase transition of $N_{f} = 3$ QCD with exact center symmetry
Tatsuhiro Misumi🇯🇵 · Takumi Iritani🇺🇸 · Etsuko Itou🇯🇵
For the $Z_{3}$ -symmetric lattice QCD-like theory ( $Z_{3}$ -QCD), in which $S U (3)$ gauge theory is coupled with three fundamental Wilson quarks with flavor-dependent twisted boundary conditions, we calculate the expectation values of Polyakov loop and chiral condensate as functions of temperature on $1 6^{3} \times 4$ and $2 0^{3} \times 4$ lattices with $m_{P S} / m_{V} = 0.70$ fixed. We find the first-order phase transition with respect to the $Z_{3}$ center symmetry, where the Polyakov loop exhibits a hysteresis depending on the initial condition of thermalization process. We also show that the crossover behavior of chiral condensate around the critical temperature of the center transition and the manifestation of flavor symmetry breaking in the high-temperature phase.
↳ hep-lathep-phnucl-thPoS(2016)·15 citations
13
Towards nature of the X(3872) resonance
N.N. Achasov🇷🇺 · E.V. Rogozina🇷🇺
We construct spectra of decays of the resonance X(3872) with good analytical and unitary properties which allows to define the branching ratio of the X(3872) \to D^{*0}\bar D^0 + c.c. decay studying only one more decay, for example, the X(3872)\to\pi^+\pi^- J/\psi(1S) decay, and show that our spectra are effective means of selection of models for the resonance X(3872). Then we discuss the scenario where the X(3872 resonance is the c\bar c = \chi_{c1}(2P) charmonium which "sits on" the D^{*0}\bar D^0 threshold. We explain the shift of the mass of the X(3872) resonance with respect to the prediction of a potential model for the mass of the \chi_{c1}(2P) charmonium by the contribution of the virtual D^*\bar D+c.c. intermediate states into the self energy of the X(3872) resonance. This allows us to estimate the coupling constant of the X(7872) resonance with the D^{*0}\bar D^0 channel, the branching ratio of the X(3872) \to D^{*0}\bar D^0 + c.c. decay, and the branching ratio of the X(3872) decay into all non-D^{*0}\bar D^0 + c.c. states. We predict a significant number of unknown decays of X(3872) via two gluons:X(3872)\to gluons\ gluon\to hadrons.
↳ hep-phhep-exnucl-thJ.Univ.Sci.Tech.China(2016)·8 citations
14
Strange meson-baryon interaction in hot and dense medium: recent progress for a road to GSI/FAIR
Daniel Cabrera🇩🇪 · Laura Tolos🇩🇪 · Jörg Aichelin🇫🇷 · Elena bratkovskaya🇩🇪
We report recent results on the dynamics of strange hadrons in two-body reactions relevant for near-threshold production in heavy-ion collisions at GSI/FAIR and NICA-Dubna. In particular, $K ˉ N$ scattering in hot and dense nuclear matter is studied within a chiral unitary framework in coupled channels, setting up the starting point for implementations in microscopic off-shell transport approaches. We focus on the calculation of transition rates with special attention to the excitation of hyperon resonances and isospin effects. Additionally, we explore "unconventional" strangeness generation by meson-meson and meson-baryon interactions in connection with recent HADES observations of deep sub-threshold $ϕ$ and $Ξ$ production.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2016)·7 citations
15
Chiral symmetry breaking and monopoles
Adriano Di Giacomo🇮🇹 · Masayasu Hasegawa🇷🇺 · Fabrizio Pucci🇧🇪
To understand the relation between the chiral symmetry breaking and monopoles, the chiral condensate which is the order parameter of the chiral symmetry breaking is calculated in the $\mbox M S$ scheme at 2 [GeV]. First, we add one pair of monopoles, varying the monopole charges $m_{c}$ from zero to four, to SU(3) quenched configurations by a monopole creation operator. The low-lying eigenvalues of the Overlap Dirac operator are computed from the gauge links of the normal configurations and the configurations with additional monopoles. Next, we compare the distributions of the nearest-neighbor spacing of the low-lying eigenvalues with the prediction of the random matrix theory. The low-lying eigenvalues not depending on the scale parameter $Σ$ are compared to the prediction of the random matrix theory. The results show the consistency with the random matrix theory. Thus, the additional monopoles do not affect the low-lying eigenvalues. Moreover, we discover that the additional monopoles increase the scale parameter $Σ$ . We then evaluate the chiral condensate in the $\mbox M S$ scheme at 2 [GeV] from the scale parameter $Σ$ and the renormalization constant $Z_{S}$ . The final results clearly show that the chiral condensate linearly decreases by increasing the monopole charges.
↳ hep-lathep-phhep-thnucl-thPoS(2016)·3 citations
16
Neutron Star Radii, Universal Relations, and the Role of Prior Distributions
A.W. Steiner🇺🇸 · J.M. Lattimer🇺🇸 · E.F. Brown🇺🇸
We investigate constraints on neutron star structure arising from the assumptions that neutron stars have crusts, that recent calculations of pure neutron matter limit the equation of state of neutron star matter near the nuclear saturation density, that the high-density equation of state is limited by causality and the largest high-accuracy neutron star mass measurement, and that general relativity is the correct theory of gravity. We explore the role of prior assumptions by considering two classes of equation of state models. In a first, the intermediate- and high-density behavior of the equation of state is parameterized by piecewise polytropes. In the second class, the high-density behavior of the equation of state is parameterized by piecewise continuous line segments. The smallest density at which high-density matter appears is varied in order to allow for strong phase transitions above the nuclear saturation density. We critically examine correlations among the pressure of matter, radii, maximum masses, the binding energy, the moment of inertia, and the tidal deformability, paying special attention to the sensitivity of these correlations to prior assumptions about the equation of state. It is possible to constrain the radii of $1.4 M_{⊙}$ neutron stars to a be larger than 10 km, even without consideration of additional astrophysical observations, for example, those from photospheric radius expansion bursts or quiescent low-mass X-ray binaries. We are able to improve the accuracy of known correlations between the moment of inertia and compactness as well as the binding energy and compactness. We also demonstrate the existence of a correlation between the neutron star binding energy and the moment of inertia.
↳ astro-ph.HEastro-ph.SRnucl-thEPJA(2016)·117 citations
17
Constraints on the $η η^{'}$ decay rate of a scalar glueball from gauge/gravity duality
Frederic Brünner🇦🇹 · Anton Rebhan🇦🇹
Predictions of glueball decay rates in the holographic Witten-Sakai-Sugimoto model for low-energy QCD can be uniquely extended to include finite quark masses up to an as yet undetermined parameter in the coupling of glueballs to the nonanomalous part of the pseudoscalar mass terms. The assumption of a universal coupling of glueballs to mass terms of the full nonet of pseudoscalar mesons leads to flavor asymmetries in the decay rates of scalar glueballs that agree well with experimental data for the glueball candidate $f_{0} (1710)$ and implies a vanishing decay rate into $η η^{'}$ pairs, for which only upper bounds for the $f_{0} (1710)$ meson are known at present from experiment. Relaxing this assumption, the holographic model gives a tight correlation between the decay rates into pairs of pseudo-Goldstone bosons of same type and $η η^{'}$ pairs. If $Γ (G \to K K) /Γ (G \to π π)$ is kept within the range reported currently by the Particle Data Group for the $f_{0} (1710)$ meson, the rate $Γ (G \to η η^{'}) /Γ (G \to π π)$ is predicted to be $≲ 0.04$ . The corresponding situation for $f_{0} (1500)$ is also discussed, which however is found to be much less compatible with the interpretation of a largely unmixed glueball.
↳ hep-phhep-thnucl-thPRD(2015)·38 citations

Affiliations

first authorsco-authorsvia INSPIRE