Nuclear Theory·nucl-th

Monday·August 29, 2022

7 papers—3 primary·4 cross-listed

04
[Submitted on 22 Aug 2022] (cross-list from quant-ph)
An Alternative Approach to Quantum Imaginary Time Evolution
Pejman Jouzdani🇺🇸 · Calvin W. Johnson🇺🇸 · Eduardo R. Mucciolo🇺🇸 · Ionel Stetcu🇺🇸
There is increasing interest in quantum algorithms that are based on the imaginary-time evolution (ITE), a successful classical numerical approach to obtain ground states. However, most of the proposals so far require heavy post-processing computational steps on a classical computer, such as solving linear equations. Here we provide an alternative approach to implement ITE. A key feature in our approach is the use of an orthogonal basis set: the propagated state is efficiently expressed in terms of orthogonal basis states at every step of the evolution. We argue that the number of basis states needed at those steps to achieve an accurate solution can be kept of the order of $n$ , the number of qubits, by controlling the precision (number of significant digits) and the imaginary-time increment. The number of quantum gates per imaginary-time step is estimated to be polynomial in $n$ . Additionally, while in many QAs the locality of the Hamiltonian is a key assumption, in our algorithm this restriction is not required. This characteristic of our algorithm renders it useful for studying highly nonlocal systems, such as the occupation-representation nuclear shell model. We illustrate our algorithm through numerical implementation on an IBM quantum simulator.
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2208.10535 [pdf]
PRA(2022)·28 citations
05
[Submitted on 25 Aug 2022] (cross-list from hep-ph)
Wave functions of $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryons
Langtian Liu🇨🇳 · Chen Chen🇨🇳 · Craig D. Roberts🇨🇳
Using a Poincaré-covariant quark+diquark Faddeev equation, we provide structural information on the four lightest $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryon multiplets. These systems may contain five distinct types of diquarks; but in order to obtain reliable results, it is sufficient to retain only isoscalar-scalar and isovector-axialvector correlations, with the latter being especially important. Viewed with low resolution, the Faddeev equation description of these states bears some resemblance to the associated quark model pictures; namely, they form a set of states related via orbital angular momentum excitation: the negative parity states are primarily $P$ -wave in character, whereas the positive parity states are $D$ wave. However, a closer look reveals far greater structural complexity than is typical of quark model descriptions, with $P$ , $D$ , $S$ , $F$ waves and interferences between them all playing a large role in forming observables. Large momentum transfer resonance electroexcitation measurements can be used to test these predictions and may thereby provide insights into the nature of emergent hadron mass.
Comments:
13 pages, 7 figures, 7 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2208.12353 [pdf]
PRD(2023)·23 citations
06
[Submitted on 26 Aug 2022] (cross-list from hep-ph)
Kinematical higher-twist corrections in $γ^{*} γ \to π π$
Cédric Lorcé🇫🇷 · Bernard Pire🇫🇷 · Qin-Tao Song🇫🇷
We apply the Braun-Manashov technique to improve the description of $γ^{*} (q_{1}) γ (q_{2}) \to M (p_{1}) M (p_{2})$ amplitudes at large $Q^{2} = - q_{1}^{2}$ and small $s = (q_{1} + q_{2})^{2}$ . We derive the kinematical higher-twist contributions of order $s / Q^{2}$ and $m^{2} / Q^{2}$ to the helicity amplitudes and estimate their sizes in the kinematics accessible at Belle and Belle II.Since pion GPDs cannot be directly measured by experiment, $π π$ GDAs are the best way to investigate the energy-momentum tensor form factors for pions.
Comments:
5 pages, 2 figures, Part of Proceedings, XXIX International Workshop on Deep-Inelastic Scattering and Related Subjects, Santiago de Compostela, Spain, May 2-6 2022
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2208.12532 [pdf]
5 citations
07
[Submitted on 26 Aug 2022] (cross-list from gr-qc)
$I -$ Love $- C$ relation for an anisotropic neutron star
H. C. Das🇮🇳
One of the most common assumptions has been made that the pressure inside the star is isotropic in nature. However, the pressure is locally anisotropic in nature which is a more realistic case. In this study, we investigate certain properties of anisotropic neutron stars with the scalar pressure anisotropy model. Different perfect fluid conditions are tested within the star with the relativistic mean-field model equation of states (EOSs). The anisotropic neutron star properties such as mass ( $M$ ), radius ( $R$ ), compactness ( $C$ ), Love number ( $k_{2}$ ), dimensionless tidal deformability ( $Λ$ ), and the moment of inertia ( $I$ ) are calculated. The magnitude of the quantities as mentioned above increases (decreases) with the positive (negative) value of anisotropy except $k_{2}$ and $Λ$ . The Universal relation $I -$ Love $- C$ is calculated with almost 58 EOSs spans from relativistic to non-relativistic cases. We observed that the relations between them get weaker when we include anisotropicity. With the help of the GW170817 tidal deformability limit and radii constraints from different approaches, we find that the anisotropic parameter is less than 1.0 if one uses the BL model. Using the universal relation and the tidal deformability bound given by the GW170817, we put a theoretical limit for the canonical radius, $R_{1.4} = 10.7 4_{- 1.36}^{+ 1.84}$ km, and the moment of inertia, $I_{1.4} = 1.7 7_{- 0.09}^{+ 0.17} \times 1 0^{45}$ g cm $^{2}$ with 90\% confidence limit for isotropic stars. Similarly, for anisotropic stars with $λ_{BL} = 1.0$ , the values are $R_{1.4} = 11.7 4_{- 1.54}^{+ 2.11}$ km, $I_{1.4} = 2.4 0_{- 0.08}^{+ 0.17} \times 1 0^{45}$ g cm $^{2}$ respectively.
Comments:
12 pages, 15 figures, 4 tables, Published in Phys. rev. D
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2208.12566 [pdf]
PRD(2022)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE

An Alternative Approach to Quantum Imaginary Time Evolution

Wave functions of (I,JP)=(21​,23​∓) baryons

Kinematical higher-twist corrections in γ∗γ→ππ

I−Love−C relation for an anisotropic neutron star

Affiliations

Wave functions of $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryons

Kinematical higher-twist corrections in $γ^{*} γ \to π π$

$I -$ Love $- C$ relation for an anisotropic neutron star