Nuclear Theory·nucl-th

Monday·March 14, 2022

9 papers—3 primary·6 cross-listed

04
Excited states and precision results for nucleon charges and form factors
Rajan Gupta🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Vincenzo Cirigliano🇺🇸 · Martin Hoferichter🇨🇭 · Yong-Chull Jang🇺🇸 · Balint Joo🇺🇸 · Emanuele Mereghetti🇺🇸 · Santanu Mondal🇺🇸 · Sungwoo Park🇺🇸 · Frank Winter🇺🇸 · Boram Yoon🇺🇸
The exponentially falling signal-to-noise ratio in all nucleon correlation functions, and the presence of towers of multihadron excited states with relatively small mass gaps makes extraction of matrix elements of various operators within the ground state nucleon challenging. Theoretically, the allowed positive parity states with the smallest mass gaps are the $N (p) π (- p)$ , $N (0) π (0) π (0)$ , $N (p) π (0)$ , $N (0) π (p), \dots$ , states. A priori, the contribution of these states arises at one loop in chiral perturbation theory ( $χ$ PT), however, in many cases the contributions are enhanced. In this talk, I will review four such cases: the correlation functions from which the axial form factors, electric and magnetic form factors, the $Θ$ -term contribution to neutron electric dipole moment (nEDM), and the pion-nucleon sigma term are extracted. Including appropriate multihadron states in the analysis can lead to significantly different results compared to standard analyses with the mass gaps taken from fits to 2-point functions. The $χ$ PT case for $N π$ states is the most clear in the axial/pseudoscalar form factors which need to satisfy the PCAC relation between them. Our analyses, supported by $χ$ PT, suggests similarly large effects in the calculations of the $Θ$ -term and the pion-nucleon sigma term that have significant phenomenological implications.
↳ hep-latnucl-thPoS(2022)·1 citation
05
Signatures of gluon saturation from structure-function measurements
Nestor Armesto🇪🇸 · Tuomas Lappi🇫🇮 · Heikki Mäntysaari🇫🇮 · Hannu Paukkunen🇫🇮 · Mirja Tevio🇫🇮
We study experimentally observable signals for nonlinear QCD dynamics in deep inelastic scattering (DIS) at small Bjorken variable $x$ and moderate virtuality $Q^{2}$ , by quantifying differences between the linear Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution and nonlinear evolution with the Balitsky-Kovchegov (BK) equation. To remove the effect of the parametrization freedom in the initial conditions of both equations, we first match the predictions for the DIS structure functions $F_{2}$ and $F_{L}$ from both frameworks in a region in $x, Q^{2}$ where both frameworks should provide an accurate description of the relevant physics. The differences in the dynamics are then quantified by the deviations when one moves away from this matching region. For free protons we find that the differences in $F_{2}$ remain at a few-percent level, while in $F_{L}$ the deviations are larger, up to $10 %$ at the EIC and $40 %$ at the LHeC kinematics. With a heavy nucleus the differences are up to $10 %$ in $F_{2}$ , and can reach $20 %$ and $60 %$ in $F_{L}$ for the EIC and the LHeC, respectively.
↳ hep-phnucl-thPRD(2022)·31 citations
06
Revisiting the chiral effective action in holographic models
Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · Daniel Logares🇪🇸
We obtain the pion decay constant and coefficients of fourth derivative terms in the chiral Lagrangian for massless quarks in the Witten-Sakai-Sugimoto model. We extract these quantities from the two-pion scattering amplitude, which we compute directly in the holographic dual through tree-level Witten diagrams. Identification of the low energy coefficients in the chiral action is subtle as their values will be shifted when the tower of massive vector bosons are integrated out. Indeed, by a direct comparison with the existing standard procedure of constructing the chiral action with radial modes in the gravity dual, we explicitly show that there are finite 't Hooft coupling corrections that have been missed. This suggests that past derivations of effective actions from holographic models may have to be revisited and future derivations more carefully considered.
↳ hep-thhep-phnucl-thPRD(2023)·4 citations
07
Opportunities for new physics searches with heavy ions at colliders
David d'Enterria🇨🇭 · Marco Drewes🇧🇪 · Andrea Giammanco🇧🇪 · Jan Hajer🇵🇹 · Elena Bratkovskaya🇩🇪 · Roderik Bruce🇨🇭 · Nazar Burmasov🇷🇺 · Mateusz Dyndal🇵🇱 · Oliver Gould🇬🇧 · Iwona Grabowska-Bold🇵🇱 · Malgorzata Gumberidze🇩🇪 · Taku Gunji🇯🇵 and 6 other authors
Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in collisions of heavy ions, mostly at the Large Hadron Collider, are summarized. A few concrete selected cases are reviewed including searches for axion-like particles, anomalous $τ$ electromagnetic moments, magnetic monopoles, and dark photons. Expectations for the achievable sensitivities of these searches in the coming years are given. Studies of CP violation in hot and dense QCD matter and connections to ultrahigh-energy cosmic rays physics are also mentioned.
↳ hep-phhep-exnucl-exnucl-thJ.Phys.G(2023)·52 citations
08
Complex scaling flows in the quench dynamics of interacting particles
Tilman Enss🇩🇪 · Noel Cuadra Braatz🇩🇪 · Giacomo Gori🇩🇪
Many-body systems driven out of equilibrium can exhibit scaling flows of the quantum state. For a sudden quench to resonant interactions between particles we construct a new class of analytical scaling solutions for the time evolved wave function with a complex scale parameter. These solutions determine the exact dynamical scaling of observables such as the pair correlation function, the contact and the fidelity. We give explicit examples of the nonequilibrium dynamics for two trapped fermions or bosons quenched to unitarity, for ideal Bose polarons, and for resonantly interacting, Borromean three-body systems. These solutions reveal universal scaling properties of interacting many-body systems that arise from the buildup of correlations at short times after the quench.
↳ cond-mat.quant-gasnucl-thquant-phPRA(2022)·4 citations
09
Hierarchy Configuration Interaction: Combining Seniority Number and Excitation Degree
Fábris Kossoski🇫🇷 · Yann Damour🇫🇷 · Pierre-François Loos🇫🇷
We propose a novel partitioning of the Hilbert space, hierarchy configuration interaction (hCI), where the excitation degree (with respect to a given reference determinant) and the seniority number (i.e., the number of unpaired electrons) are combined in a single hierarchy parameter. The key appealing feature of hCI is that each hierarchy level accounts for all classes of determinants whose number share the same scaling with system size. By surveying the dissociation of multiple molecular systems, we found that the overall performance of hCI usually exceeds or, at least, parallels that of excitation-based CI. For higher orders of hCI and excitation-based CI, the additional computational burden related to orbital optimization usually do not compensate the marginal improvements compared with results obtained with Hartree-Fock orbitals. The exception is orbital-optimized CI with single excitations, a minimally correlated model displaying the qualitatively correct description of single bond breaking, at a very modest computational cost.
↳ physics.chem-phcond-mat.mtrl-scicond-mat.str-elnucl-th+1J.Phys.Chem.Lett.(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Excited states and precision results for nucleon charges and form factors

Signatures of gluon saturation from structure-function measurements

Revisiting the chiral effective action in holographic models

Opportunities for new physics searches with heavy ions at colliders

Complex scaling flows in the quench dynamics of interacting particles

Hierarchy Configuration Interaction: Combining Seniority Number and Excitation Degree

Affiliations