Nuclear Theory·nucl-th

Friday·November 6, 2020

9 papers—2 primary·7 cross-listed

03
Quantum Interference in Jet Substructure from Spinning Gluons
Hao Chen🇨🇳 · Ian Moult🇺🇸 · Hua Xing Zhu🇨🇳
Collimated sprays of hadrons, called jets, are an emergent phenomenon of Quantum Chromodynamics (QCD) at collider experiments, whose detailed internal structure encodes valuable information about the interactions of high energy quarks and gluons, and their confinement into color-neutral hadrons. The flow of energy within jets is characterized by correlation functions of energy flow operators, with the three-point correlator, being the first correlator with non-trivial shape dependence, playing a special role in unravelling the dynamics of QCD. In this Letter we initiate a study of the three-point energy correlator to all orders in the strong coupling constant, in the limit where two of the detectors are squeezed together. We show that by rotating the two squeezed detectors with respect to the third by an angle $ϕ$ , a $cos (2 ϕ)$ dependence arising from the quantum interference between intermediate virtual gluons with $+ / -$ helicity is imprinted on the detector. This can be regarded as a double slit experiment performed with jet substructure, and it provides a direct probe of the ultimately quantum nature of the substructure of jets, and of transverse spin physics in QCD. To facilitate our all-orders analysis, we adopt the Operator Product Expansion (OPE) for light-ray operators in conformal field theory and develop it in QCD. Our application of the light-ray OPE in real world QCD establishes it as a powerful theoretical tool with broad applications for the study of jet substructure.
↳ hep-phhep-exhep-thnucl-ex+1PRL(2021)·116 citations
04
CP violating effects in $^{210}$ Fr and prospects for new physics beyond the Standard Model
Nanako Shitara🇯🇵 · Nodoka Yamanaka🇺🇸 · Bijaya Kumar Sahoo🇮🇳 · Toshio Watanabe🇯🇵 · Bhanu Pratap Das🇯🇵
We report theoretical results of the electric dipole moment (EDM) of $^{210}$ Fr which arises from the interaction of the EDM of an electron with the internal electric field in an atom and the scalar-pseudoscalar electron-nucleus interaction; the two dominant sources of CP violation in this atom. Employing the relativistic coupled-cluster theory, we evaluate the enhancement factors for these two CP violating interactions to an accuracy of about 3% and analyze the contributions of the many-body effects. These two quantities in combination with the projected sensitivity of the $^{210}$ Fr EDM experiment provide constraints on new physics beyond the Standard Model. Particularly, we demonstrate that their precise values are necessary to account for the effect of the bottom quark in models in which the Higgs sector is augmented by nonstandard Yukawa interactions such as the two-Higgs doublet model.
↳ hep-phnucl-thphysics.atom-phJHEP(2021)·14 citations
05
Weinberg operator contribution to the nucleon electric dipole moment in the quark model
Nodoka Yamanaka🇺🇸 · Emiko Hiyama🇯🇵
We evaluate the contribution of the CP violating gluon chromo-electric dipole moment (the so-called Weinberg operator, denoted as $w$ ) to the electric dipole moment (EDM) of nucleons in the nonrelativistic quark model. The CP-odd interquark potential is modeled by the perturbative one-loop level gluon exchange generated by the Weinberg operator with massive quarks and gluons. The nucleon EDM is obtained by solving the nonrelativistic Schrödinger equation of the three-quark system using the Gaussian expansion method. It is found that the resulting nucleon EDM, which may reasonably be considered as the irreducible contribution, is smaller than the one obtained after $γ_{5}$ -rotating the anomalous magnetic moment using the CP-odd mass calculated with QCD sum rules. We estimate the total contribution to be $d_{n} = w \times 20 e MeV$ and $d_{p} = - w \times 18 e MeV$ with 60% of theoretical uncertainty.
↳ hep-phhep-exnucl-exnucl-thPRD(2021)·39 citations
06
Quantum kinetic theory for spin-1/2 fermions in Wigner function formalism
Jian-Hua Gao🇨🇳 · Zuo-Tang Liang🇨🇳 · Qun Wang🇨🇳
We give a brief overview of the kinetic theory for spin-1/2 fermions in Wigner function formulism. The chiral and spin kinetic equations can be derived from equations for Wigner functions. A general Wigner function has 16 components which satisfy 32 coupled equations. For massless fermions, the number of independent equations can be significantly reduced due to the decoupling of left-handed and right-handed particles. It can be proved that out of many components of Wigner functions and their coupled equations, only one kinetic equation for the distribution function is independent. This is called the disentanglement theorem for Wigner functions of chiral fermions. For massive fermions, it turns out that one particle distribution function and three spin distribution functions are independent and satisfy four kinetic equations. Various chiral and spin effects such as chiral magnetic and votical effects, the chiral seperation effect, spin polarization effects can be consistently described in the formalism.
↳ hep-phhep-thnucl-thInt.J.Mod.Phys.A(2021)·34 citations
07
Cumulative effects of collision integral, strong magnetic field, and quasiparticle description on charge and heat transport in thermal QCD medium
Salman Ahamad Khan🇮🇳 · Binoy Krishna Patra🇮🇳
Our first aim is to explore the effect of the collision integral with the insurance of instantaneous conservation of particle number on charge and heat transport in a thermal QCD medium. The second aim is to see how the dimensional reduction due to strong magnetic field (B) modulates the transport through the entangled effects, {\em such as} collision-time and occupation probability etc. in collision integral. The final aim is to check how the quasiparticle description through dispersion relation of thermal QCD in strong B, alters the aforesaid conclusions. We observe that modified collision term expedites both transport, which is manifested by large magnitudes of electrical ( $σ_{el}$ ) and thermal ( $κ$ ) conductivities, in comparison to relaxation-collision term. As a corollary, Lorenz number is dominated by the later and Knudsen number is by the former. However, strong B not only flips the dominance of collision term in heat transport, it also causes drastic enhancement of both $σ_{el}$ and $κ$ and reduction in specific heat. As a result, the equilibration factor, Knudsen number becomes much larger than one, which defies physical interpretation. Finally, quasiparticle description in the absence of strong B impedes the transport of charge and heat, resulting in the meagre decrease of conductivities, however, strong B does noticeable observations: conductivities now gets reduced to physically plausible values, T-dependence of $σ_{el}$ gets reversed, {\em i.e.} it now decreases with T, effect of collision integral gets smeared in $κ$ etc. Knudsen number thus becomes much smaller than one, implying that the system be remained in equilibrium. These findings attribute to the fact that the collective modes in the dispersion relation of thermal QCD in strong B sets in much larger scale, manifested by large in-medium masses.
↳ hep-phcond-mat.softcond-mat.stat-mechcond-mat.str-el+1PRD(2021)·16 citations
08
Comparing conserved charge fluctuations from lattice QCD to HRG model calculations
Jishnu Goswami🇩🇪 · Frithjof Karsch🇩🇪 · Christian Schmidt🇩🇪 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸
We present results from lattice QCD calculations for $2^{n d}$ and $4^{t h}$ order cumulants of conserved charge fluctuations and correlations, and compare these with various HRG model calculations. We show that differences between HRG and QCD calculations already show up in the second order cumulants close to the pseudo-critical temperature for the chiral transition in (2+1)-flavor QCD and quickly grow large at higher temperatures. We also show that QCD results for strangeness fluctuations are enhanced over HRG model calculations which are based only on particles listed in the Particle Data Group tables as 3-star resonances. This suggests the importance of contributions from additional strange hadron resonances. We furthermore argue that additional (repulsive) interactions, introduced either through excluded volume (mean field) HRG models or the S-matrix approach, do not improve the quantitative agreement with $2^{n d}$ and $4^{t h}$ order cumulants calculated in lattice QCD. HRG based approaches fail to describe the thermodynamics of strongly interacting matter at or shortly above the pseudo-critical temperature of QCD.
↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·21 citations
09
Superconducting phases in a two-component microscale model of neutron star cores
Toby S. Wood · Vanessa Graber · William G. Newton
We identify the possible ground states for a mixture of two superfluid condensates (one neutral, the other electrically charged) using a phenomenological Ginzburg-Landau model. While this framework is applicable to any interacting condensed-matter mixture of a charged and a neutral component, we focus on nuclear matter in neutron star cores, where proton and neutron condensates are coupled via non-dissipative entrainment. We employ the Skyrme interaction to determine the neutron star's equilibrium composition, and hence obtain realistic coefficients for our Ginzburg-Landau model at each depth within the star's core. We then use the Ginzburg-Landau model to determine the ground state in the presence of a magnetic field. In this way, we obtain superconducting phase diagrams for six representative Skyrme models, revealing the microphysical magnetic flux distribution throughout the neutron star core. The phase diagrams are rather complex and the locations of most of the phase transitions can only be determined through numerical calculations. Nonetheless, we find that for all equations of state considered in this work, much of the outer core exhibits type-1.5 superconductivity, rather than type-II superconductivity as is generally assumed. For local magnetic field strengths $≲ 1 0^{14} G$ , the magnetic flux is distributed inhomogeneously, with bundles of magnetic fluxtubes separated by flux-free Meissner regions. We provide an approximate criterion to determine the transition between this type-1.5 phase and the type-I region in the inner core.
↳ cond-mat.supr-conastro-ph.HEastro-ph.SRnucl-th13 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum Interference in Jet Substructure from Spinning Gluons

CP violating effects in 210Fr and prospects for new physics beyond the Standard Model

Weinberg operator contribution to the nucleon electric dipole moment in the quark model

Quantum kinetic theory for spin-1/2 fermions in Wigner function formalism

Cumulative effects of collision integral, strong magnetic field, and quasiparticle description on charge and heat transport in thermal QCD medium

Comparing conserved charge fluctuations from lattice QCD to HRG model calculations

Superconducting phases in a two-component microscale model of neutron star cores

Affiliations

CP violating effects in $^{210}$ Fr and prospects for new physics beyond the Standard Model