Nuclear Theory·nucl-th

Tuesday·August 18, 2020

14 papers—8 primary·6 cross-listed

09
[Submitted on 14 Aug 2020] (cross-list from hep-ph)
Covariantizing Phase Space
Andrew J. Larkoski🇺🇸 · Tom Melia🇯🇵
We covariantize calculations over the manifold of phase space, establishing Stokes' theorem for differential cross sections and providing new definitions of familiar observable properties like infrared and collinear safety. Through the introduction of explicit coordinates and a metric we show phase space is isomorphic to the product space of a simplex and a hypersphere, and we identify geometric phenomena that occur when its dimensions are large. These results have implications for fixed order subtraction schemes, machine learning in particle physics and high-multiplicity heavy ion collisions.
Comments:
6 pages, 1 figure; v2: PRD version, extended discussion of IRC safe and additive observables from Stokes' theorem
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.06508 [pdf]
PRD(2020)·24 citations
10
[Submitted on 14 Aug 2020] (cross-list from hep-lat)
P-Wave Two-Particle Bound and Scattering States in a Finite Volume including QED
Gianluca Stellin🇩🇪 · Ulf-G. Meißner🇩🇪
The mass shifts for two-fermion bound and scattering P-wave states subject to the long-range interactions due to QED in the non-relativistic regime are derived. Introducing a short range force coupling the spinless fermions to one unit of angular momentum in the framework of pionless EFT, we first calculate both perturbatively and non-perturbatively the Coulomb corrections to fermion-fermion scattering in the continuum and infinite volume context. Motivated by the research on particle-antiparticle bound states, we extend the results to fermions of identical mass and opposite charge. Second, we transpose the system onto a cubic lattice with periodic boundary conditions and we calculate the finite volume corrections to the energy of the lowest bound and unbound $T_{1}^{\pm}$ eigenstates. In particular, power law corrections proportional to the fine structure constant and resembling the recent results for S-wave states are found. Higher order contributions in $α$ are neglected, since the gapped nature of the momentum operator in the lattice environnement allows for a perturbative treatment of the QED interactions.
Comments:
73 pages, 7 figures, 0 tables. To be submitted to the European Physical Journal A
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2008.06553 [pdf]
EPJA(2021)·9 citations
11
[Submitted on 16 Aug 2020] (cross-list from hep-ph)
Determination of the masses and decay widths of the well-established $s$ and $p$ baryon resonances below $2$ GeV
Evangelos Matsinos
This study appertains to the extraction of estimates for the masses and for the partial decay widths to pion-nucleon final states of the well-established (four-star) $s$ and $p$ baryon resonances below $2$ GeV. These estimates are exclusively obtained from the data contained in the recent compilation by the Particle Data Group. Only the $N$ ( $S = 0, I = 1/2$ ) and the $Δ$ ( $S = 0, I = 3/2$ ) states are considered, where $S$ and $I$ denote strangeness and total isospin, respectively.
Comments:
17 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.06919 [pdf]
3 citations
12
[Submitted on 17 Aug 2020] (cross-list from hep-ph)
Triangle singularity as the origin of $X_{0} (2900)$ and $X_{1} (2900)$ observed in $B^{+} \to D^{+} D^{-} K^{+}$
Xiao-Hai Liu · Mao-Jun Yan🇨🇳 · Hong-Wei Ke · Gang Li🇨🇳 · Ju-Jun Xie🇨🇳
The LHCb collaboration reported the observation of a narrow peak in the $D^{-} K^{+}$ invariant mass distributions from the $B^{+} \to D^{+} D^{-} K^{+}$ decay. The peak is parameterized in terms of two resonances $X_{0} (2900)$ and $X_{1} (2900)$ with the quark contents $c ˉ s ˉ u d$ , and their spin-parity quantum numbers are $0^{+}$ and $1^{-}$ , respectively. We investigate the rescattering processes which may contribute to the $B^{+} \to D^{+} D^{-} K^{+}$ decays. It is shown that the $D^{*-} K^{*+}$ rescattering via the $χ_{c 1} K^{*+} D^{*-}$ loop or the $D ˉ_{1}^{0} K^{0}$ rescattering via the $D_{s J}^{+} D ˉ_{1}^{0} K^{0}$ loop simulate the $X_{0} (2900)$ and $X_{1} (2900)$ structures. Such phenomena are due to the analytical property of the scattering amplitudes with the triangle singularities located to the vicinity of the physical boundary.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.07190 [pdf]
EPJC(2020)·92 citations
13
[Submitted on 17 Aug 2020] (cross-list from hep-ph)
Open charm and bottom tetraquarks in an extended relativized quark model
Qi-Fang Lü🇨🇳 · Dian-Yong Chen🇨🇳 · Yu-Bing Dong🇨🇳
In present work, we systematically calculate the mass spectra of open charm and bottom tetraquarks $q q q ˉ Q ˉ$ within an extended relativized quark model. The four-body relativized Hamiltonians including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections are solved by using the variational method. It is found that the predicted masses of four $0^{+}$ $u d s ˉ c ˉ$ states are 2765, 3065, 3152, and 3396 MeV, which disfavor the assignment of the newly observed $X_{0} (2900)$ as a compact tetraquark. Moreover, the whole mass spectra of the open charm and bottom tetraquarks show quite similar patterns, which preserve the light flavor SU(3) symmetry and heavy quark symmetry well. In addition, our results suggest that the flavor exotic states $nn s ˉ c ˉ$ , $nn s ˉ b ˉ$ , $ss n ˉ c ˉ$ , and $ss n ˉ b ˉ$ and their antiparticles can be searched in the heavy-light meson plus kaon final states by future experiments. More theoretical and experimental efforts are needed to investigate these singly heavy tetraquarks.
Comments:
11 pages, 3 figures, comments and suggestions are welcome
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2008.07340 [pdf]
PRD(2020)·79 citations
14
[Submitted on 17 Aug 2020] (cross-list from physics.atm-clus)
Efimov effect in non-integer dimensions induced by an external field
E. Garrido · A.S. Jensen
The Efimov effect can be induced by means of an external deformed one-body field that effectively reduces the allowed spatial dimensions to less than three. To understand this new mechanism, conceptually and practically, we employ a formulation using non-integer dimension, which is equivalent to the strength of an external oscillator field. The effect most clearly appears when the crucial two-body systems are unbound in three, but bound in two, dimensions. We discuss energy variation, conditions for occurrence, and number of Efimov states, as functions of the dimension. We use practical examples from cold atom physics of $^{133}$ Cs- $^{133}$ Cs- $^{133}$ Cs, $^{87}$ Rb- $^{87}$ Rb- $^{87}$ Rb, $^{133}$ Cs- $^{133}$ Cs- $^{6}$ Li, and $^{87}$ Rb- $^{87}$ Rb- $^{39}$ K. Laboratory tests of the effect can be performed with two independent parameters, i.e. the external one-body field and the Feshbach two-body tuning. The scaling and (dis)appearance of these Efimov states occur precisely as already found in three dimensions.
Comments:
6 pages, 5 figures. To be published in Physics Letters A
Subjects:
physics.atm-clus (physics.atm-clus); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2008.07392 [pdf]
PLA(2021)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Covariantizing Phase Space

P-Wave Two-Particle Bound and Scattering States in a Finite Volume including QED

Determination of the masses and decay widths of the well-established s and p baryon resonances below 2 GeV

Triangle singularity as the origin of X0​(2900) and X1​(2900) observed in B+→D+D−K+

Open charm and bottom tetraquarks in an extended relativized quark model

Efimov effect in non-integer dimensions induced by an external field

Affiliations

Determination of the masses and decay widths of the well-established $s$ and $p$ baryon resonances below $2$ GeV

Triangle singularity as the origin of $X_{0} (2900)$ and $X_{1} (2900)$ observed in $B^{+} \to D^{+} D^{-} K^{+}$