Nuclear Theory·nucl-th

Tuesday·July 21, 2015

12 papers—4 primary·8 cross-listed

05
How to reveal the exotic nature of the P_c(4450)
Feng-Kun Guo🇩🇪 · Ulf-G. Meißner🇩🇪 · Wei Wang🇨🇳 · Zhi Yang🇩🇪
The LHCb Collaboration announced two pentaquark-like structures in the $J / ψ p$ invariant mass distribution. We show that the current information on the narrow structure at 4.45 GeV is compatible with kinematical effects of the rescattering from $χ_{c 1} p$ to $J / ψ p$ : First, it is located exactly at the $χ_{c 1} p$ threshold. Second, the mass of the four-star well-established $Λ (1890)$ is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the $χ_{c 1} p$ threshold, and third, there is a narrow structure at the $χ_{c 1} p$ threshold but not at the $χ_{c 0} p$ and $χ_{c 2} p$ thresholds. In order to check whether that structure corresponds to a real exotic resonance, one has to measure the process $Λ_{b}^{0} \to K^{-} χ_{c 1} p$ . If the $P_{c} (4450)$ structure exists in the $χ_{c 1} p$ invariant mass distribution as well, then the structure cannot be just a kinematical effect but is a real resonance, otherwise, one cannot conclude the $P_{c} (4450)$ to be another exotic hadron. In addition, it is also worthwhile to measure the decay $Υ (1 S) \to J / ψ p p ˉ$ : a narrow structure at 4.45 GeV but not at the $χ_{c 0} p$ and $χ_{c 2} p$ thresholds would exclude the possibility of a pure kinematical effect.
↳ hep-phhep-exhep-latnucl-thPRD(2015)·357 citations
06
Magnetotransport in Dirac metals: chiral magnetic effect and quantum oscillations
Gustavo M. Monteiro🇺🇸 · Alexander G. Abanov🇺🇸 · Dmitri E. Kharzeev🇺🇸
Dirac metals are characterized by the linear dispersion of fermionic quasi-particles, with the Dirac point hidden inside a Fermi surface. We study the magnetotransport in these materials using chiral kinetic theory to describe within the same framework both the negative magnetoresistance caused by chiral magnetic effect and quantum oscillations in the magnetoresistance due to the existence of the Fermi surface. We discuss the relevance of obtained results to recent measurements on $C d_{3} A s_{2}$ .
↳ cond-mat.mes-hallhep-phnucl-thPRB(2015)·11 citations
07
The Proton Mass and Scale-Invariant Hidden Local Symmetry for Compressed Baryonic Matter
Mannque Rho🇫🇷
I discuss how to access dense baryonic matter of compact stars by combining hidden local symmetry (HLS) of light-quark vector mesons with spontaneously broken scale invariance of a (pseudo) Nambu-Goldstone boson, dilaton, in a description that parallels the approach to dilatonic Higgs. Some of the surprising observations are that the bulk of proton mass is not Nambu-Goldstonian, parity doubling emerges at high density and the EoS of baryonic matter can be soft enough for heavy-ion processes at low density and stiff enough at high density for $\sim 2$ solar mass neutron stars.
↳ hep-phnucl-thInt.J.Mod.Phys.A(2017)·4 citations
08
$D ˉ Σ_{c}^{*}$ and $D ˉ^{*} Σ_{c}$ interactions and the LHCb hidden-charmed pentaquarks
Jun He🇨🇳
Very recently, two hidden-charmed resonances $P_{c} (4380)$ and $P_{c} (4450)$ consistent with pentaquark states were observed at the LHCb detector. The two $P_{c}$ states locate just below the $D ˉ Σ_{c}^{*}$ and $D ˉ^{*} Σ_{c}$ thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this fact we perform a dynamical investigation about the $D ˉ Σ_{c}^{*} (2520)$ and $D ˉ^{*} Σ_{c} (2455)$ interactions which are described by the meson exchanges. A bound state which carries spin-parity $J^{P} = 3/ 2^{-}$ is produced from the $D ˉ Σ_{c}^{*} (2520)$ interaction, which is consistent with the $P_{c} (4380)$ observed at the LHCb detector. From the $D^{*} Σ_{c} (2455)$ interaction, a bound state with $5/ 2^{+}$ is produced, which can be related to the $P_{c} (4450)$ . The results suggest that the $P_{c} (4380)$ and $P_{c} (4450)$ are good candidates of $D ˉ Σ_{c}^{*} (2520)$ and $D ˉ^{*} Σ_{c} (2455)$ molecular states, respectively.
↳ hep-phhep-exhep-latnucl-ex+1PLB(2016)·256 citations
09
Centrality and transverse momentum dependence of elliptic flow of multi-strange hadrons and $ϕ$ meson in Au+Au collisions at $s_{N N}$ = 200 GeV
STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · A. Aparin · D. Arkhipkin · E. C. Aschenauer · G. S. Averichev · X. Bai · V. Bairathi and 323 other authors
We present high precision measurements of elliptic flow near midrapidity ( $∣ y ∣ < 1.0$ ) for multi-strange hadrons and $ϕ$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $s_{N N} =$ 200 GeV. We observe that the transverse momentum dependence of $ϕ$ and $Ω$ $v_{2}$ is similar to that of $π$ and $p$ , respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30 $%$ and 30-80 $%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $ϕ$ and proton $v_{2}$ at low transverse momentum in the 0-30 $%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$ .
↳ nucl-exhep-exhep-phnucl-thPRL(2016)·120 citations
10
Understanding the newly observed heavy pentaquark candidates
Xiao-Hai Liu🇯🇵 · Qian Wang🇩🇪 · Qiang Zhao🇨🇳
We find that several thresholds can contribute to the enhancements of the newly observed heavy pentaquark candidates $P_{c}^{+} (4380)$ and $P_{c}^{+} (4450)$ via the anomalous triangle singularity (ATS) transitions in the specific kinematics of $Λ_{b} \to J / ψ K^{-} p$ . Apart from the observed two peaks we find that another peaks around 4.5 GeV can also be produced by the ATS. We also show that the $Σ_{c}^{(*)}$ can be produced at leading order in $Λ_{b}$ decay. This process is different from the triangle diagram and its threshold enhancement only appears as CUSP effects if there is no pole structure or the ATS involved. The threshold interaction associated with the presence of the ATS turns out to be a general phenomenon and plays a crucial role in the understanding of candidates for exotic states.
↳ hep-phhep-exnucl-exnucl-thPLB(2016)·288 citations
11
Landau quantization and mass-radius relation of magnetized White Dwarfs in general relativity
Somnath Mukhopadhyay🇮🇳 · Debasis Atta🇮🇳 · D.N. Basu🇮🇳
Recently, several white dwarfs have been proposed with masses significantly above the Chandrasekhar limit, known as Super-Chandrasekhar White Dwarfs, to account for the overluminous Type Ia supernovae. In the present work, Equation of State of a completely degenerate relativistic electron gas in magnetic field based on Landau quantization of charged particles in a magnetic field is developed. The mass-radius relations for magnetized White Dwarfs are obtained by solving the Tolman-Oppenheimer-Volkoff equations. The effects of the magnetic energy density and pressure contributed by a density-dependent magnetic field are treated properly to find the stability configurations of realistic magnetic White Dwarf stars.
↳ astro-ph.SRgr-qcnucl-thRom.Rep.Phys.(2017)·10 citations
12
Initial state fluctuations from mid-peripheral to ultra-central collisions in a event-by-event transport approach
Salvatore Plumari🇮🇹 · Giovanni Luca Guardo🇮🇹 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹
We have developed a relativistic kinetic transport approach that incorporates initial state fluctuations allowing to study the build up of elliptic flow $v_{2}$ and high order harmonics $v_{3}$ , $v_{4}$ and $v_{5}$ for a fluid at fixed $η / s (T)$ . We study the effect of the $η / s$ ratio and its T dependence on the build up of the $v_{n} (p_{T})$ for two different beam energies: RHIC for Au+Au at $s = 200 G e V$ and LHC for $P b + P b$ at $s = 2.76 T e V$ . We find that for the two different beam energies considered the suppression of the $v_{n} (p_{T})$ due to the viscosity of the medium have different contributions coming from the cross over or QGP phase. Our study reveals that only in ultra-central collisions ( $0 - 0.2%$ ) the $v_{n} (p_{T})$ have a stronger sensitivity to the T dependence of $η / s$ in the QGP phase and this sensitivity increases with the order of the harmonic n. Moreover, the study of the correlations between the initial spatial anisotropies $ϵ_{n}$ and the final flow coefficients $v_{n}$ shows that at LHC energies there is more correlation than at RHIC energies. The degree of correlation increases from peripheral to central collisions, but only in ultra-central collisions at LHC, we find that the linear correlation coefficient $C (n, n) \approx 1$ for $n = 2, 3, 4$ and $5$ . This suggests that the final correlations in the ( $v_{n}$ , $v_{m}$ ) space reflect the initial correlations in the ( $ϵ_{n}$ , $ϵ_{m}$ ) space.
↳ hep-phnucl-thPRC(2015)·72 citations

Affiliations

first authorsco-authorsvia INSPIRE