Update on the lattice calculation of K→ππ decays with G-parity boundary conditions on a second lattice spacing
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73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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Results for “Parity”
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Codes with Parity Conditions on Subsets of Coordinates
Binary codes with the constraint that the codes restricted to certain subsets of columns must be contained in particular codes of the shorter lengths are considered. In particular, codes of even length 2k, and of minimum distance approximately greater than d, where in the code obtained by restricting to the first k positions has even weight and at the same time the code obtained by restricting to the last k positions also has even weight are considered. If k = 2n, n odd, and d = 2n, it is proved that the code has at most 8n - 4 codewords, and 8n - 4 is attainable for n = 3. This permits a file-transfer protocol control function assignment for personal computers to be chosen for 20 control functions using essentially just pairs of upper-case alphabetic ASCII characters where the Hamming distance between the binary forms of every two different control functions is at least six.
Posner, E. C.↗
Codes With Parity Conditions on Subsets of Coordinates
New theorems aid search for efficient code alphabets. Paper discusses theory of finding largest binary codes 2k bits in length, in which all words differ from each other in at least d places and in which words truncated by ignoring certain subsets of bit positions belong to shorter linear codes.
Posner, E.↗
Parity-nonconserving transitions in Cs and Tl - A semiempirical treatment of core-polarization effects
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Parpia, F. A.↗
Time-resolved laser-induced fluorescence of selected even-parity 7p states of Xe I
Lifetimes and self-quenching rates have been measured for excited states of Xe I that were populated using simultaneous two-photon absorption. Lifetimes measured in this study are somewhat shorter than those measured using the broadband-excitation technique. Lifetimes reported here are all faster than 100 nsec. Deactivation rates are approximately 2 x 10 to the -10th cu cm/sec per mol.
Mcgee, T. J.↗
Improvements on Low-Density Parity-Check (LDPC) Codes and High-Performance Neuromorphic Engineering for Communication Systems
Belief propagation (BP) on LDPC codes is an iterative decoding algorithm that performs information transfer on the Tanner graph, which represents the code. In each iteration, the algorithm exchanges information (LLR) between variable nodes and check nodes through the edges of the graph. LLR values represent the probability that a given bit in a transmitted codeword equals 0 or 1, given a received word. In the hardware part, recent advancements in intelligent technologies, such as artificial intelligence, big data analytics, autonomous vehicles, and speech/image recognition, have heightened the demand for faster calculations and reduced energy consumption.
Danilo Barrionuevo↗
New Ritz wavelengths and transition probabilities for parity-forbidden, singly ionized nickel [Ni ii ] lines of astrophysical interest
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Christian P Clear↗
New Ritz Wavelengths and Transition Probabilities of Parity-forbidden [Mn II] Lines of Astrophysical Interest
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Florence S. Liggins↗
Measurement of Parity Violating Asymmetry in Elastic Electron Scattering off 48Ca
Atomic nuclei are composed of nucleons governed by the strong nuclear force. Although the proton distributions in nuclei are well measured with electromagnetic probes, the neutron distributions are relatively unconstrained. The nuclear symmetry energy governs the distribution of the excess neutrons in asymmetric nuclei, as well as the dynamics of neutron-rich nuclear matter up to the scale of neutron stars….
Clarke, Cameron↗
Chiral-like doublet band structure and octupole correlations in 104 Ag
The nature of the yrast negative-parity band and its chiral-like partner band in 104 Ag is investigated experimentally and theoretically. Lifetimes of states in the negative-parity yrast band and positive-parity band based on the 4424-keV level are measured using Doppler shift attenuation technique. Lifetimes of three more states have been determined along with the upper limit for the lifetime of the highest observed yrast states. Further, lifetimes known from earlier studies are determined with better precision. The level scheme of 104 Ag has also been extended with the addition of new enhanced E1 transitions linking the positive-parity band based on the 4424-keV levels and the yrast negative-parity and its partner band. B(E1) and/or B(E1)/B(M1) values for the transitions from the positive-parity band to the yrast and its partner band have been determined for the first time; these suggest strong octupole correlation between the positive-parity and the negative-parity bands. Here, calculations based on the triaxial projected shell model (TPSM) and covariant density functional theory (CDFT) have been performed to unravel the intrinsic structures of the partner band and the excited positive-parity band. TPSM calculations predict that doublet bands have significant angular momentum contributions along the three principle axes, suggesting that bands could have chiral symmetry breaking origin. The CDFT calculations predict a π(g 9/2 ) -1 Ⓧν(h 11/2 )(g 7/2 ,d 5/2 ) 2 aligned quasiparticle configuration for the negative-parity doublet bands with deformation parameters β≈0.20 and γ≈5°. The partner band could be interpreted as a chiral vibration mode built on top of the yrast band. The excited positive-parity band is predicted to have aligned four quasiparticle configurations, namely, π(g 9/2 ) -1 Ⓧν(h 11/2 ) 2 (g 7/2 ,d 5/2 ) 1 . Further, these calculations predict significant octupole softness in 104 Ag which could be the reason for enhanced E1 transitions between the four quasiparticle positive-parity bands and the doublet negative-parity bands.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Onset of band structure in 70 Ga
Excited states in the odd-odd nucleus 70 Ga were studied using the 62 Ni( 14 C, αpn) fusion-evaporation reaction at the John D. Fox Superconducting Accelerator Laboratory at Florida State University with a 50 MeV beam. Depopulating γ rays were measured in coincidence with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. Analysis of γ–γ coincidences led to the addition of 16 new transitions to the 70 Ga level scheme, including transitions associated with the onset of a new positive-parity band structure likely based on the πg 9/2 ⊗ νg 9/2 configuration. Spins and parities were assigned using directional correlation of oriented nuclei (DCO) ratios and linear polarization measurements. Shell-model calculations with the JUN45 effective interaction reproduce the excitation energies of the positive-parity states reasonably well but predict negative-parity states that are typically 400–500 keV lower than observed. Furthermore, total Routhian surface calculations for the lowest positive-parity configuration with signature α = 0 indicate significant triaxiality (γ ≈ −20°) and the development of competing non-collective excitations at J = 8, corresponding to the experimentally observed onset of the positive-parity band. Similar features are found in the calculated surfaces for the lowest negative-parity states with α = 0.
59 ≤ A ≤ 89↗
Spacecraft dynamics characterization and control system failure detection. Volume 3: Control system failure monitoring
We discuss the application of Generalized Parity Relations to two experimental flexible space structures, the NASA Langley Mini-Mast and Marshall Space Flight Center ACES mast. We concentrate on the generation of residuals and make no attempt to implement the Decision Function. It should be clear from the examples that are presented whether it would be possible to detect the failure of a specific component. We derive the equations from Generalized Parity Relations. Two special cases are treated: namely, Single Sensor Parity Relations (SSPR) and Double Sensor Parity Relations (DSPR). Generalized Parity Relations for actuators are also derived. The NASA Langley Mini-Mast and the application of SSPR and DSPR to a set of displacement sensors located at the tip of the Mini-Mast are discussed. The performance of a reduced order model that includes the first five models of the mast is compared to a set of parity relations that was identified on a set of input-output data. Both time domain and frequency domain comparisons are made. The effect of the sampling period and model order on the performance of the Residual Generators are also discussed. Failure detection experiments where the sensor set consisted of two gyros and an accelerometer are presented. The effects of model order and sampling frequency are again illustrated. The detection of actuator failures is discussed. We use Generalized Parity Relations to monitor control system component failures on the ACES mast. An overview is given of the Failure Detection Filter and experimental results are discussed. Conclusions and directions for future research are given.
Vanschalkwyk, Christiaan M.↗
Observation of collective modes of excitations in 59 Co, 59 Ni, and 61 Co and the influence of the $g_{9/2}$ orbital
High-spin states in 59 Co (Z = 27), 59 Ni (Z = 28), and 61 Co have been populated by the fusion evaporation reactions, 48 Ti( 14 C, p2n ) 59 Co, 48 Ti( 14 C, 3 n ) 59 Ni, and 50 Ti( 14 C, p2n ) 61 Co. The 9 MV tandem accelerator at the John D. Fox Laboratory, Florida State University (FSU) was used to accelerate the 14 C beam and the deexciting γ rays were detected by the FSU detector array consisting of six high-purity germanium (HPGe) clover detectors and three single crystals. Directional correlation of the $γ$ rays deexciting oriented states (DCO ratios) and polarization asymmetry measurements helped to establish spin and parities of the excited states whenever possible. The level scheme of 59 Co has been expanded with the inclusion of positive-parity states up to 31/2 + at around 11 MeV. The 59 Ni positive-parity states known from previous study were verified with modifications to some of the spins and parities. On the other hand, the negative-parity states were extended to 31/2 at an excitation energy of 12 MeV. No new transition was observed for 61 Co, but one of the major bands has been reassigned as consisting of positive-parity states by reason of this study. Importantly, excitations observed within the f 7/2 , p 3/2 , f 5/2 , and p 1/2 orbitals, and also across the N = 40 subshell closure into the g 9/2 orbital was established by comparison with large-scale shell-model calculations for the three nuclei studied.
59 ≤ A ≤ 89↗
P not PQ
Parity solutions to the strong CP problem are a compelling alternative to approaches based on Peccei-Quinn symmetry, particularly given the expected violation of global symmetries in a theory of quantum gravity. The most natural of these solutions break parity at a low scale, giving rise to a host of experimentally accessible signals. We assess the status of the simplest parity-based solution in light of LHC data and flavor constraints, highlighting the prospects for near-future tests at colliders, tabletop experiments, and gravitational wave observatories. The origin of parity breaking and associated gravitational effects play crucial roles, providing new avenues for discovery through EDMs and gravity waves. These experimental opportunities underline the promise of generalized parity, rather than Peccei-Quinn symmetry, as a robust and testable solution to the strong CP problem.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Fault-tolerant multichannel demultiplexer subsystems
Fault tolerance in future processing and switching communication satellites is addressed by showing new methods for detecting hardware failures in the first major subsystem, the multichannel demultiplexer. An efficient method for demultiplexing frequency slotted channels uses multirate filter banks which contain fast Fourier transform processing. All numerical processing is performed at a lower rate commensurate with the small bandwidth of each bandbase channel. The integrity of the demultiplexing operations is protected by using real number convolutional codes to compute comparable parity values which detect errors at the data sample level. High rate, systematic convolutional codes produce parity values at a much reduced rate, and protection is achieved by generating parity values in two ways and comparing them. Parity values corresponding to each output channel are generated in parallel by a subsystem, operating even slower and in parallel with the demultiplexer that is virtually identical to the original structure. These parity calculations may be time shared with the same processing resources because they are so similar.
Redinbo, Robert↗
Structure of 30 Mg explored via in-beam γ-ray spectroscopy
In the island of inversion, ground states of neutron-rich sd-shell nuclei exhibit strong admixtures of intruder configurations from the fp shell. The nucleus 30 Mg, located at the boundary of the island of inversion, serves as a cornerstone to track the structural evolution as one approaches this region. Spin-parity assignments for excited states in 30 Mg, especially negative-parity levels, have yet to be established. In the present work, the nuclear structure of 30Mg was investigated by in-beam gamma-ray spectroscopy mainly focusing on firm spin-parity determinations. High-intensity rare-isotope beams of 31 Mg, 32 Mg, 34 Si, and 35 P bombarded a Be target to induce nucleon removal reactions populating states in 30 Mg. Gamma rays were detected by the state-of-the-art gamma-ray tracking array GRETINA. For the direct one-neutron removal reaction, final-state exclusive cross sections and parallel momentum distributions were deduced. Multi-nucleon removal reactions from different projectiles were exploited to gain complementary information. With the aid of the parallel momentum distributions, an updated level scheme with revised spin-parity assignments was constructed. Spectroscopic factors associated with each state were also deduced. Results were confronted with large-scale shell-model calculations using two different effective interactions, showing excellent agreement with the present level scheme. Furthermore, a marked difference in the spectroscopic factors indicates that the full delineation of the transition into the island of inversion remains a challenge for theoretical models.
20 ≤ A ≤ 38↗
Structure of the Majorana Clifford group
In quantum information science, Clifford operators and stabilizer codes play a central role for systems of qubits (or qudits). In this study, we study their analogs for systems composed of Majorana fermions. In this case, a crucial role is played by fermion parity symmetry, which is an unbreakable symmetry present in any system with fundamentally fermionic degrees of freedom. We prove that the subgroup of parity-preserving Majorana Cliffords can be represented by the orthogonal group over the binary field 𝔽 2 , and we show how it can be generated by braiding operators and used to construct any (even-parity) Majorana stabilizer code. We also analyze the frame potential for this so-called p-Clifford group when acting on a fixed-parity sector of the Hilbert space, proving that it is equivalent to the frame potential of the ordinary Clifford group acting on the same sector.
Computational complexity↗
Level Structure of {sup 31}S Via {sup 32}S({ital p,d}) {sup 31}S
Background: Properties of proton-unbound S-31 states determine the P-30(p, gamma) S-31 reaction rate, which has a significant impact on explosive hydrogen burning in classical novae and type-I x-ray bursts. Despite several previous studies, uncertainties still remain with respect to the nuclear structure of S-31 near the proton threshold. Purpose: The level structure of S-31 has been presently investigated via a charged-particle spectroscopy experiment using the S-32(p, d) S-31 reaction. Method: Deuterons corresponding to S-31 excited states with 3.285 <= E-x <= 10.8 MeV were momentum analyzed via an Enge split-pole spectrograph at six laboratory angles between 10 degrees and 62 degrees. Differential cross sections of the S-32(p, d)S-31 reaction were measured at E-p = 34.5 MeV. Distorted-wave Born approximation calculations were performed to constrain the spin-parity assignments of several of the observed levels. Results: We have detected 72 excited states of S-31, out of which 17 are within the astrophysical region of interest corresponding to the temperature range of 0.1-1.5 GK. We have resolved the discrepancy in the spin and parity of an excited state with E-x = 6542 keV, showing that is it not J(pi) = 3/2(-), and therefore the contribution of this state to the P-30(p, gamma) reaction rate is likely much less significant than previously thought owing to the larger angular-momentum transfer required to populate this excited state. Moreover, our measurement results help consolidate the spin-parity assignments for the 6377 and 6636 keV states in S-31. Conclusions: This work presents the most comprehensive spin-parity assignments to date from a single-neutron transfer reaction on S-32 to S-31 excited states in the region between 6 to 7 MeV excitation energy. This region is significant for the determination of the P-30(p, gamma)S-30 reaction rate over the temperatures characteristic of explosive hydrogen burning in novae.
Setoodehnia, K.↗