Nuclear Theory·nucl-th

Tuesday·February 9, 2021

16 papers—7 primary·9 cross-listed

08
Radiative corrections to nucleon weak charges and Beyond Standard Model impact
Leendert Hayen🇺🇸
The nucleon axial charge is a central ingredient in nuclear and particle physics, and a key observable in precision tests of the electroweak Standard Model sector and beyond. We report on the first complete calculation of its electroweak quantum corrections up to $O (α)$ , using a combination of current algebra techniques and QCD sum rules. We find a substantial enhancement due to the weak magnetism contribution in the elastic channel, and include higher-twist and target mass corrections at low $Q^{2}$ to find $Δ_{R}^{A} = 0.02881 (22)$ . Using analogous methods, we determine a new value for the vector charge renormalization, $Δ_{R}^{V} = 0.02474 (27)$ , and show how the two most recent calculations can be brought into agreement. This allows us to determine a corrected experimental $g_{A}^{0} = 1.2730 (13)$ , which is a $> 2 σ$ shift away from the commonly quoted value. We use this new result to set constraints on exotic right-handed currents by comparing to lattice QCD results, and resolve a double-counting issue in the $∣ V_{u d} ∣$ extraction from mirror decays.
↳ hep-phnucl-exnucl-th11 citations
09
Fermion propagator in a rotating environment
Alejandro Ayala🇲🇽 · L. A. Hernández🇿🇦 · K. Raya🇲🇽 · R. Zamora🇨🇱
We apply the exponential operator method to derive the propagator for a fermion immersed within a rigidly rotating environment with cylindrical geometry. Given that the rotation axis provides a preferred direction, Lorentz symmetry is lost and the general solution is not translationally invariant in the radial coordinate. However, under the approximation that the fermion is completely dragged by the vortical motion, valid for large angular velocities, translation invariance is recovered. The propagator can then be written in momentum space. The result is suited to be used applying ordinary Feynman rules for perturbative calculations in momentum space.
↳ hep-phhep-thnucl-thPRD(2021)·23 citations
10
Critical behaviour of hydrodynamic series
M. Asadi (1)🇮🇷 · H. Soltanpanahi (2 and 3)🇨🇳 · Farid Taghinavaz (1) ((1) IPM, Tehran, (2) South China Normal University, Guangzhou, (3) Jagiellonian University, Krakow)🇮🇷
We investigate the time-dependent perturbations of strongly coupled $N = 4$ SYM theory at finite temperature and finite chemical potential with a second order phase transition. This theory is modelled by a top-down Einstein-Maxwell-dilaton description which is a consistent truncation of the dimensional reduction of type IIB string theory on AdS $_{5} \times$ S $^{5}$ . We focus on spin-1 and spin-2 sectors of perturbations and compute the linearized hydrodynamic transport coefficients up to the third order in gradient expansion. We also determine the radius of convergence of the hydrodynamic mode in spin-1 sector and the lowest non-hydrodynamic modes in spin-2 sector. Analytically, we find that all the hydrodynamic quantities have the same critical exponent near the critical point $θ = 1/2$ . Moreover, we establish a relation between symmetry enhancement of the underlying theory and vanishing the only third order hydrodynamic transport coefficient $θ_{1}$ , which appears in the shear dispersion relation of a conformal theory on a flat background.
↳ hep-thcond-mat.str-elhep-phmath-ph+2JHEP(2021)·16 citations
11
High Energy Behaviour of Light Meson Photoproduction
Moskov J. Amaryan (ODU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Michael G. Ryskin (PNPI)🇷🇺 · Igor I. Strakovsky (GWU)🇺🇸
We evaluated recent CLAS Collaboration measurements for the $9 0^{\circ}$ meson photoproduction off the nucleon using a tagged photon beam spanning the energy interval $s = 3 - 11$ GeV $^{2}$ . The results are compared with the "Quark Counting Rules" predictions.
↳ hep-phhep-exnucl-exnucl-thPRC(2021)·6 citations
12
Condensation of Cooper Triples
Sora Akagami🇯🇵 · Hiroyuki Tajima🇯🇵 · Kei Iida🇯🇵
The condensation of Cooper pairs, originating from the Fermi-surface instability due to a weakly attractive interaction between two fermions, opened a new frontier for exploring many-body physics in interdisciplinary contexts. In this work, we discuss the possible condensation of Cooper triples, which are three-body counterparts of Cooper pairs for three-component fermions with a three-body attraction. Although each composite trimer-like state obeys the Fermi-Dirac statistics, its aggregate can form a condensate at zero center-of-mass momentum in the presence of the internal degrees of freedom associated with the relative momenta of constituent particles of momenta close to the Fermi surface. Such condensation can be regarded as bosonization in infinite-component fermions. We propose a variational wave function for the condensate of Cooper triples in analogy with the Bardeen-Cooper-Schrieffer ground state and obtain the ground-state energy.
↳ cond-mat.quant-gascond-mat.supr-conhep-phnucl-thPRA(2021)·16 citations
13
Electronic width of the $ψ (3770)$ resonance interfering with the background
N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺
Methods for extracting the $ψ (3770) \to e^{+} e^{-}$ decay width from the data on the reaction cross section $e^{+} e^{-} \to D D ˉ$ are discussed. Attention is drawn to the absence of the generally accepted method for determining $Γ_{ψ (3770) e^{+} e^{-}}$ in the presence of interference between the contributions of the $ψ (3770)$ resonance and background. It is shown that the model for the experimentally measured $D$ meson form factor, which satisfies the requirement of the Watson theorem and takes into account the contribution of the complex of the mixed $ψ (3770)$ and $ψ (2 S)$ resonances, allows uniquely determine the value of $Γ_{ψ (3770) e^{+} e^{-}}$ by fitting. The $Γ_{ψ (3770) e^{+} e^{-}}$ values found from the data processing are compared with the estimates in the potential models.
↳ hep-phhep-exnucl-thPRD(2021)·5 citations
14
Relativistic corrections to decays of heavy baryons in the quark model
Ahmad Jafar Arifi🇯🇵 · Daiki Suenaga🇯🇵 · Atsushi Hosaka🇯🇵
We investigate relativistic corrections of order $1/ m^{2}$ , where $m$ is the constituent quark mass, to heavy baryon decays by emitting one pseudoscalar meson in the quark model. This work is motivated by shortcomings in the previous studies in the nonrelativistic quark model for decays of the Roper-like states such as $Λ_{c} (2765)$ . We find that the relativistic corrections due to the internal motion of quarks are essential ingredients in improving their decay properties such that the decay widths are significantly increased. In addition, such corrections can explain a phenomenological suppression of the quark axial-vector coupling constant $g_{A}^{q}$ for the $Σ_{c} (2455)$ and $Σ_{c} (2520)$ decays.
↳ hep-phnucl-thPRD(2021)·36 citations
15
The axial charge of the triton from lattice QCD
Assumpta Parreño🇪🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸 · Frank Winter🇺🇸 · Emmanuel Chang · William Detmold🇺🇸 · Marc Illa🇪🇸
The axial charge of the triton is investigated using lattice quantum chromodynamics (QCD). Extending previous work at heavier quark masses, calculations are performed using three ensembles of gauge field configurations generated with quark masses corresponding to a pion mass of 450 MeV. Finite-volume energy levels for the triton, as well as for the deuteron and diproton systems, are extracted from analysis of correlation functions computed on these ensembles, and the corresponding energies are extrapolated to infinite volume using finite-volume pionless effective field theory (FVEFT). It is found with high likelihood that there is a compact bound state with the quantum numbers of the triton at these quark masses. The axial current matrix elements are computed using background field techniques on one of the ensembles and FVEFT is again used to determine the axial charge of the proton and triton. A simple quark mass extrapolation of these results and earlier calculations at heavier quark masses leads to a value of the ratio of the triton to proton axial charges at the physical quark masses of $g_{A}^{^{3} H} / g_{A}^{p} = 0.91 + 0.07 - 0.09$ . This result is consistent with the ratio determined from experiment and prefers values less than unity (in which case the triton axial charge would be unmodified from that of the proton), thereby demonstrating that QCD can explain the modification of the axial charge of the triton.
↳ hep-lathep-phnucl-thPRD(2021)·23 citations
16
Isochronic evolution and the radioactive decay of r-process nuclei
T. M. Sprouse · G. Wendell Misch · M. R. Mumpower
We report on the creation and application of a novel decay network that uses the latest data from experiment and evaluation. We use the network to simulate the late-time phase of the rapid neutron capture (r) process. In this epoch, the bulk of nuclear reactions, such as radiative capture, have ceased and nuclear decays are the dominant transmutation channels. We find that the decay from short-lived to long-lived species naturally leads to an isochronic evolution in which nuclei with similar half-lives are populated at the same time. We consider random perturbations along each isobaric chain to initial solar-like r-process compositions to demonstrate the isochronic nature of the late-time phase of the r-process. Our analysis shows that detailed knowledge of the final isotopic composition allows for the prediction of late-time evolution with a high degree of confidence despite uncertainties that exist in astrophysical conditions and the nuclear physics properties of the most neutron-rich nuclei. We provide the time-dependent nuclear composition in the Appendix as supplemental material.
↳ astro-ph.HEnucl-thApJ(2022)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE