Nuclear Theory·nucl-th

Wednesday·May 22, 2019

6 papers—1 primary·5 cross-listed

02
[Submitted on 22 Apr 2019] (cross-list from hep-ph)
Hidden-charm pentaquarks and $P_{c}$ states
Xin-Zhen Weng🇨🇳 · Xiao-Lin Chen🇨🇳 · Wei-Zhen Deng🇨🇳 · Shi-Lin Zhu🇨🇳
Recently, the LHCb Collaboration reported three $P_{c}$ states in the $J / ψ p$ channel. We systematically study the mass spectrum of the hidden charm pentaquark in the framework of an extended chromomagnetic model. For the $nnn c c ˉ$ pentaquark with $I = 1/2$ , we find that (i) the lowest state is $P_{c} (4327.0, 1/2, 1/ 2^{-})$ [We use $P_{c} (m, I, J^{P})$ to denote the $nnn c c ˉ$ pentaquark], which corresponds to the $P_{c} (4312)$ . Its dominant decay mode is $Λ_{c} D ˉ^{*}$ . (ii) We find two states in the vicinity of $P_{c} (4380)$ . The first one is $P_{c} (4367.4, 1/2, 3/ 2^{-})$ and decays dominantly to $N J / ψ$ and $Λ_{c} D ˉ^{*}$ . The other one is $P_{c} (4372.4, 1/2, 1/ 2^{-})$ . Its dominant decay mode is $Λ_{c} D ˉ$ , and its partial decay width of $N η_{c}$ channel is comparable to that of $N J / ψ$ . (iii) In higher mass region, we find $P_{c} (4476.3, 1/2, 3/ 2^{-})$ and $P_{c} (4480.9, 1/2, 1/ 2^{-})$ , which correspond to $P_{c} (4440)$ and $P_{c} (4457)$ . In the open charm channels, both of them decay dominantly to the $Λ_{c} D ˉ^{*}$ . (iv) We predict two states above $4.5 GeV$ , namely $P_{c} (4524.5, 1/2, 3/ 2^{-})$ and $P_{c} (4546.0, 1/2, 5/ 2^{-})$ . The masses of the $nnn c c ˉ$ state with $I = 3/2$ are all over $4.6 GeV$ . Moreover, we use the model to explore the $nn sc c ˉ$ , $ss n c c ˉ$ and $sssc c ˉ$ pentaquark states.
Comments:
18 pages, 4 figure; revised version accepted by PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1904.09891 [pdf]
PRD(2019)·119 citations
03
[Submitted on 19 May 2019] (cross-list from cond-mat.stat-mech)
A note on the connection between non-additive entropy and $h$ -derivative
Jin-Wen Kang · Ke-Ming Shen · Ben-Wei Zhang
In order to study as a whole a wide part of entropy measures, we introduce a two-parameter non-extensive entropic form with respect to the $h$ -derivative, which generalizes the conventional Newton--Leibniz calculus. This new entropy, $S_{h, h^{'}}$ , is proved to describe the non-extensive systems and recover several types of well-known non-extensive entropic expressions, such as the Tsallis entropy, the Abe entropy, the Shafee entropy, the Kaniadakis entropy and even the classical Boltzmann--Gibbs one. As a generalized entropy, its corresponding properties are also analyzed.
Comments:
9 pages, 1 figure, accepted for publication in Entropy (MDPI)
Subjects:
Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
1905.07706 [pdf]
Entropy(2023)·0 citations
04
[Submitted on 20 May 2019] (cross-list from quant-ph)
Short-depth circuits for efficient expectation value estimation
Alessandro Roggero🇺🇸 · Alessandro Baroni🇺🇸
The evaluation of expectation values $T r [ρO]$ for some pure state $ρ$ and Hermitian operator $O$ is of central importance in a variety of quantum algorithms. Near optimal techniques developed in the past require a number of measurements $N$ approaching the Heisenberg limit $N = O (1/ ϵ)$ as a function of target accuracy $ϵ$ . The use of Quantum Phase Estimation requires however long circuit depths $C = O (1/ ϵ)$ making their implementation difficult on near term noisy devices. The more direct strategy of Operator Averaging is usually preferred as it can be performed using $N = O (1/ ϵ^{2})$ measurements and no additional gates besides those needed for the state preparation. In this work we use a simple but realistic model to describe the bound state of a neutron and a proton (the deuteron) and show that the latter strategy can require an overly large number of measurement in order to achieve a reasonably small relative target accuracy $ϵ_{r}$ . We propose to overcome this problem using a single step of QPE and classical post-processing. This approach leads to a circuit depth $C = O (ϵ^{μ})$ (with $μ \geq 0$ ) and to a number of measurements $N = O (1/ ϵ^{2 + ν})$ for $0 < ν \leq 1$ . We provide detailed descriptions of two implementations of our strategy for $ν = 1$ and $ν \approx 0.5$ and derive appropriate conditions that a particular problem instance has to satisfy in order for our method to provide an advantage.
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
1905.08383 [pdf]
PRA(2020)·19 citations
05
[Submitted on 21 May 2019] (cross-list from hep-ph)
$P_{c} (4457)^{+}$ , $P_{c} (4440)^{+}$ , and $P_{c} (4312)^{+}$ : molecules or compact pentaquarks?
Jian-Bo Cheng🇨🇳 · Yan-Rui Liu🇨🇳
In a chromomagnetic model, we analyse the properties of the newly observed $P_{c} (4457)^{+}$ , $P_{c} (4440)^{+}$ , and $P_{c} (4312)^{+}$ states. We estimate the masses of the $(uu d)_{8_{c}} (c c ˉ)_{8_{c}}$ and $(u d s)_{8_{c}} (c c ˉ)_{8_{c}}$ pentaquark states by considering the isospin breaking effects. Their values are determined by calculating mass distances from the $Σ_{c}^{++} D^{-}$ and $Ξ_{c}^{' +} D^{-}$ thresholds, respectively. It is found that the isospin breaking effects on the spectrum are small. From the uncertainty consideration and the rearrangement decay properties in a simple model, we find that it is possible to assign the $P_{c} (4457)^{+}$ , $P_{c} (4440)^{+}$ , and $P_{c} (4312)^{+}$ as $J^{P} = 3/ 2^{-}$ , $1/ 2^{-}$ , and $3/ 2^{-}$ pentaquark states, respectively. The assignment in the molecule picture can be different, in particular for the $P_{c} (4312)^{+}$ . The information from open-charm channels, e.g. $B [P_{c} \to Σ_{c}^{++} D^{-}] / B [P_{c} \to J / ψ p]$ , will play an important role in distinguishing the inner structures of the $P_{c}$ states. Discussions and predictions based on the calculations are also given.
Comments:
15 pages, 2 figures, 8 tables. Version accepted by PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1905.08605 [pdf]
PRD(2019)·106 citations
06
[Submitted on 21 May 2019] (cross-list from hep-ph)
Gluon propagator in two-color dense QCD: Massive Yang-Mills approach at one-loop
Daiki Suenaga🇨🇳 · Toru Kojo🇨🇳
We study the Landau gauge gluon propagators in dense two-color QCD at quark chemical potential, $μ_{q}$ , in the range from 0.5 to 1.0 GeV not reachable by the perturbative method at weak coupling. In order to take into account the non-perturbative effects, at tree level we use a massive Yang-Mills model for the Yang-Mills theory (or the Curci-Ferrari model) which has successfully described the lattice results of the gluon and ghost propagators in the Landau gauge. We couple quarks to this theory and compute the one-loop polarization effects in medium. The presence of the gluon mass significantly tempers the medium effects and uncertainties associated with the strong coupling constant $α_{s}$ . The diquark condensate in two-color QCD is color-singlet, for which neither electric nor magnetic screening masses should appear at the scale less than the diquark gap. The presence of the gap helps to explain the lattice results which are not very sensitive to the quark density. Meanwhile we also found the limitation of the one-loop estimate as well as the lack of some physics in perturbative medium corrections.
Comments:
16 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1905.08751 [pdf]
PRD(2019)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE

Hidden-charm pentaquarks and Pc​ states

A note on the connection between non-additive entropy and h-derivative

Short-depth circuits for efficient expectation value estimation

Pc​(4457)+, Pc​(4440)+, and Pc​(4312)+: molecules or compact pentaquarks?

Gluon propagator in two-color dense QCD: Massive Yang-Mills approach at one-loop

Affiliations

Hidden-charm pentaquarks and $P_{c}$ states

A note on the connection between non-additive entropy and $h$ -derivative

$P_{c} (4457)^{+}$ , $P_{c} (4440)^{+}$ , and $P_{c} (4312)^{+}$ : molecules or compact pentaquarks?