Nuclear Theory·nucl-th

Friday·January 3, 2020

11 papers—2 primary·9 cross-listed

03
The hidden-charm strong decays of the $Z_{c}$ states
Li-Ye Xiao🇨🇳 · Guang-Juan Wang🇨🇳 · Shi-Lin Zhu🇨🇳
Inspired by BESIII's measurement of the decay $Z_{c} (3900)^{\pm} \to ρ^{\pm} η_{c}$ , we calculate the branching fraction ratio between the $ρ η_{c}$ and $π J / ψ$ decay modes for the charged states $Z_{c} (3900)$ , $Z_{c} (4020)$ and $Z_{c} (4430)$ using a quark interchange model. Our results show that (i) the ratio $R_{Z_{c} (3900)} = \frac{B ( Z _{c} ( 3900 ) ^{\pm} \to ρ ^{\pm} η _{c} )}{B ( Z _{c} ( 3900 ) ^{\pm} \to π ^{\pm} J / ψ )}$ is 1.3 and 1.6 in the molecular and tetraquark scenarios respectively, which is roughly consistent with the experimental data $R^{exp} = 2.2 \pm 0.9$ . (ii) The ratios $\frac{Γ [ Z _{c} ( 3900 ) \to ρ η _{c} ]}{Γ [ Z _{c} ( 4020 ) \to ρ η _{c} ]}$ and $\frac{Γ [ Z _{c} ( 3900 ) \to π J / ψ ]}{Γ [ Z _{c} ( 4020 ) \to π J / ψ ]}$ are about 12.5 and 24.2, respectively in the molecular scenario. In contrast, these ratios are about 1.2 in the tetraquark scenario. The non-observation of the $Z_{c} (4020)$ signal in the $π J / ψ$ decay mode strongly indicates that $Z_{c} (3900)$ and $Z_{c} (4020)$ are molecule-like signals which arise from the $D^{(*)} D ˉ^{(*)}$ hadronic interactions.
↳ hep-phhep-exhep-latnucl-thPRD(2020)·28 citations
04
The multilayer structure of protons
I.M. Dremin🇷🇺
It is argued that the dynamics of the elastic scattering of high-energy protons at intermediate transferred momenta changes with the energy increase. It evolves from the multiple scattering at the external layer for energies about 10 GeV to the double scattering at the two subsequent layers within the colliding protons for energies about 10 TeV. The problem of the unitarity is considered in this context.
↳ hep-phhep-exnucl-exnucl-thEPJC(2020)·10 citations
05
The 2020 Skyrmionics Roadmap
C. Back · V. Cros · H. Ebert · K. Everschor-Sitte · A. Fert · M. Garst · Tianping Ma · S. Mankovsky · T. L. Monchesky · M. Mostovoy · N. Nagaosa · S.S.P. Parkin and 7 other authors
The notion of non-trivial topological winding in condensed matter systems represents a major area of present-day theoretical and experimental research. Magnetic materials offer a versatile platform that is particularly amenable for the exploration of topological spin solitons in real space such as skyrmions. First identified in non-centrosymmetric bulk materials, the rapidly growing zoology of materials systems hosting skyrmions and related topological spin solitons includes bulk compounds, surfaces, thin films, heterostructures, nano-wires and nano-dots. This underscores an exceptional potential for major breakthroughs ranging from fundamental questions to applications as driven by an interdisciplinary exchange of ideas between areas in magnetism which traditionally have been pursued rather independently. The skyrmionics roadmap provides a review of the present state of the art and the wide range of research directions and strategies currently under way. These are, for instance, motivated by the identification of the fundamental structural properties of skyrmions and related textures, processes of nucleation and annihilation in the presence of non-trivial topological winding, an exceptionally efficient coupling to spin currents generating spin transfer torques at tiny current densities, as well as the capability to purpose-design broad-band spin dynamic and logic devices.
↳ cond-mat.str-elcond-mat.mes-hallhep-phnucl-th41 citations
06
Randall-Sundrum Model with a Dilaton Field at Finite Temperature
Aditya Dhumuntarao🇺🇸 · Joseph I. Kapusta🇺🇸 · Christopher Plumberg🇸🇪
We find exact finite temperature solutions to $d = 5$ Einstein-dilaton gravity with black branes and a Randall--Sundrum 3-brane. We show that there exists a unique generating superpotential for these models. The location of the black brane and the associated Hawking temperature depend on the value of the the 3-brane tension while other parameters are held fixed. The thermodynamics of these solutions are presented, from which we show that the entropy satisfies $S < Vol (R^{3}) /4 G_{5}$ . We demonstrate that in a certain limit the gauge dual of this theory effectively reduces to $N = 4$ SYM at finite temperature on $S^{1} \times R^{3}$
↳ hep-thnucl-thPRD(2020)·2 citations
07
Do Proton-Proton collisions at the LHC energies produce Droplets of Quark-Gluon Plasma?
Raghunath Sahoo🇮🇳
The proton-proton ( $pp$ ) collisions at the Large Hadron Collider (LHC), CERN, Switzerland has brought up new challenges and opportunities in understanding the experimental findings in contrast to the conventional lower energy $pp$ collisions. Usually $pp$ collisions are used as the baseline measurement at the GeV and TeV energies in order to understand a possible high density QCD medium formation in heavy-ion collisions. However, the TeV $pp$ collisions have created a new domain of research, where scientists have started observing heavy-ion-like features (signatures) in high-multiplicity $pp$ collisions. This warrants a relook into TeV $pp$ collisions, if at all QGP-droplets are produced in such collisions. In this presentation, I discuss some of the new findings and concepts emerging out in $pp$ collisions at the LHC energies along with some of the new emergent phenomena in particle production.
↳ hep-phhep-exnucl-exnucl-thSpringer Proc.Phys.(2020)·3 citations
08
Ernest Henley and the shape of baryons
Alfons J. Buchmann🇩🇪
Calculations of pion-baryon couplings, baryon quadrupole and octupole moments, baryon spin and orbital angular momentum done in collaboration with Ernest Henley are reviewed. A common theme of this work is the shape of baryons. Also, a personal account of my work with Ernest Henley during the period 1999-2013 is given.
↳ hep-phnucl-thIJMPE(2019)·2 citations
09
Thermomagnetic properties and Debye Screening for magnetized quark-gluon Plasma using the extended self-consistent quasiparticle model
Sebastian Koothottil🇮🇳 · Vishnu M. Bannur🇮🇳
The thermomagnetic behavior of quark-gluon plasma has recently received a lot of attention. In this work, we make use of the extended self-consistent quasiparticle model to study the thermodynamic properties of magnetized (2+1) flavor quark-gluon plasma. The system is considered as a non-interacting system of quasiparticles with masses depending on both temperature and magnetic field. This allows obtaining the equation of state of the system and the other thermodynamic properties such as the speed of sound. We use the extended self-consistent model to obtain the magnetization and show that QGP has a paramagnetic nature. In addition, we study the pressure anisotropy and calculate the transverse pressure. The obtained anisotropic pressure may be used in hydrodynamic studies of magnetized QGP produced in heavy-ion collisions. Finally, we examine the screening properties of magnetized QGP in the longitudinal direction by calculating the Debye screening mass.
↳ hep-phhep-thnucl-thPRC(2020)·18 citations
10
Structure and EM form factors of purely relativistic systems
V.A. Karmanov🇷🇺 · J. Carbonell🇫🇷 · H. Sazdjian🇫🇷
The Bethe-Salpeter equation for two massive scalar particles interacting by scalar massless exchange has solutions of two types, which differ from each other by their behavior in the non-relativistic limit: the normal solutions which turn into the Coulomb ones and the "abnormal" solutions. The latter ones have no non-relativistic counterparts and disappear in the non-relativistic limit. We studied the composition of all these states. It turns out that the normal states, even for large binding energy, are dominated by two massive particles. Whereas, the contribution of the two-body sector into the abnormal states, even for small binding energy, is of the order of 1% only; they are dominated by an indefinite number of the massless particles. The elastic electromagnetic form factors for both normal and abnormal states, as well as the transition ones between them, are calculated.
↳ hep-phhep-thnucl-thPoS(2020)·4 citations
11
Electromagnetic character of the competitive $γ γ / γ$ -decay from $^{137 m}$ Ba
P.-A. Söderström · L. Capponi · E. Açıksöz · T. Otsuka · N. Tsoneva · Y. Tsunoda · D. L. Balabanski · N. Pietralla · G. L. Guardo · D. Lattuada · H. Lenske · C. Matei and 3 other authors
Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double- $β$ decay, and stimulated atomic two-photon transitions. For the electromagnetic nuclear interaction, the observation of the competitive double- $γ$ decay from $^{137 m}$ Ba has opened up the nuclear structure field for detailed investigation of second-order processes through the manifestation of off-diagonal nuclear polarizability. Here we confirm this observation with an $8.7 σ$ significance, and an improved value on the double-photon versus single-photon branching ratio as $2.62 \times 1 0^{- 6} (30)$ . Our results, however, contradict the conclusions from the original experiment, where the decay was interpreted to be dominated by a quadrupole-quadrupole component. Here, we find a substantial enhancement in the energy distribution consistent with a dominating octupole-dipole character and a rather small quadrupole-quadrupole element in the decay, hindered due to an evolution of the internal nuclear structure. The implied strongly hindered double-photon branching in $^{137 m}$ Ba opens up the possibility of the double-photon branching as a feasible tool for nuclear-structure studies on off-diagonal polarizability in nuclei where this hindrance is not present.
↳ nucl-exnucl-thNature Commun.(2020)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE