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Nuclear Theory·nucl-th

Thursday·October 20, 2022

8 papers—2 primary·6 cross-listed

All8Primary2Cross-lists6
  1. 03

    Exciting the long-lived Higgs mode in superfluid Fermi gases with particle removal

    Guitao Lyu · Kui-Tian Xi · Sukjin Yoon · Qijin Chen · Gentaro Watanabe

    Experimental evidence of the Higgs mode in strongly interacting superfluid Fermi gases had not been observed until recently [Behrle et al., Nat. Phys. 14, 781 (2018)]. Due to the coupling with other collective modes and quasiparticle excitations, generating stable Higgs-mode oscillations is challenging. We study how to excite long-lived Higgs-mode oscillations in a homogeneous superfluid Fermi gas in the BCS-BEC crossover. We find that the Higgs mode can be excited by time-periodically modulating the scattering length at an appropriate amplitude and frequency. However, even for a modulation frequency below twice the pairing-gap energy, quasiparticles are still excited through the generation of higher harmonics due to nonlinearity in the superfluid. More importantly, we find that persistent Higgs-mode oscillations with almost constant amplitude can be produced by removing particles at an appropriate momentum, and the oscillation amplitude can be controlled by the number of removed particles. Finally, we propose two ways to experimentally realize particle removal.

    ↳ cond-mat.quant-gascond-mat.supr-connucl-thquant-phPRA(2023)·5 citations
  2. 04

    Multi-Collinear Splitting Kernels for Track Function Evolution

    Hao Chen🇨🇳 · Max Jaarsma🇳🇱 · Yibei Li🇨🇳 · Ian Moult🇺🇸 · Wouter J. Waalewijn🇳🇱 · Hua Xing Zhu🇨🇳

    Jets and their substructure play a central role in many analyses at the Large Hadron Collider (LHC). To improve the precision of measurements, as well as to enable measurement of jet substructure at increasingly small angular scales, tracking information is often used due to its superior angular resolution and robustness to pile-up. Calculations of track-based observables involve non-perturbative track functions, that absorb infrared divergences in perturbative calculations and describe the transition to charged hadrons. The infrared divergences are directly related to the renormalization group evolution (RGE), and can be systematically computed in perturbation theory. Unlike the standard DGLAP evolution, the RGE of the track functions is non-linear, encoding correlations in the fragmentation process. We compute the next-to-leading order (NLO) evolution of the track functions, which involves in its kernel the full splitting function. We discuss in detail how how we implement the evolution equation numerically, and illustrate the size of the NLO corrections. We also show that our equation can be viewed as a master equation for collinear evolution at NLO, by illustrating that by integrating out specific terms, one can derive the evolution for any -hadron fragmentation function. Our results provide a crucial ingredient for obtaining track-based predictions for generic measurements at the LHC, and for improving the description of the collinear dynamics of jets.

    ↳ hep-phhep-exnucl-thJHEP(2023)·46 citations
  3. 05

    Collinear Parton Dynamics Beyond DGLAP

    Hao Chen🇨🇳 · Max Jaarsma🇳🇱 · Yibei Li🇨🇳 · Ian Moult🇺🇸 · Wouter J. Waalewijn🇳🇱 · Hua Xing Zhu🇨🇳

    Renormalization group evolution equations describing the scale dependence of quantities in quantum chromodynamics (QCD) play a central role in the interpretation of experimental data. Arguably the most important evolution equations for collider physics applications are the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations, which describe the evolution of a quark or gluon fragmenting into hadrons, with only a single hadron identified at a time. In recent years, the study of the correlations of energy flow within jets has come to play a central role at collider experiments, necessitating an understanding of correlations, going beyond the standard DGLAP paradigm. In this Letter we derive a general renormalization group equation describing the collinear dynamics that account for correlations in the fragmentation. We compute the kernel of this evolution equation at next-to-leading order (NLO), where it involves the splitting functions, and develop techniques to solve it numerically. We show that our equation encompasses all previously-known collinear evolution equations, namely DGLAP and the evolution of multi-hadron fragmentation functions. As an application of our results, we consider the phenomenologically-relevant example of energy flow on charged particles, computing the energy fraction in charged particles in hadrons at NNLO. Our results are an important step towards improving the understanding of the collinear dynamics of jets, with broad applications in jet substructure, ranging from the study of multi-hadron correlations, to the description of inclusive (sub)jet production, and the advancement of modern parton showers.

    ↳ hep-phhep-exnucl-thPRD(2025)·49 citations
  4. 06

    Different Coalescence Sources of Light Nuclei Production in Au-Au Collisions at GeV

    Rui-Qin Wang🇨🇳 · Ji-Peng Lv🇨🇳 · Yan-Hao Li🇨🇳 · Jun Song🇨🇳 · Feng-Lan Shao🇨🇳

    We study the production of light nuclei in the coalescence mechanism in Au-Au collisions at midrapidity at GeV. We derive analytic formulas of momentum distributions of two bodies, three bodies and four nucleons coalescing into light nuclei, respectively. We naturally explain the transverse momentum spectra of the deuteron (), triton (), helium-3 (He) and helium-4 (He). We reproduce the data of yield rapidity densities and averaged transverse momenta of , , He and He. We give proportions of contributions from different coalescence sources for , He and He in their productions. We find that besides nucleon coalescence, nucleonnucleus coalescence and nucleusnucleus coalescence may play requisite roles in light nuclei production in Au-Au collisions at GeV.

    ↳ hep-phnucl-thCPC(2024)·6 citations
  5. 07

    Dilepton production in the photodisintegration of the deuteron

    Mengchu Cai🇨🇳 · Tianbo Liu🇨🇳 · Bo-Qiang Ma🇨🇳

    We study the lepton pair production in the photodisintegration of the deuteron process. The complete seven-fold differential cross section is calculated via the Bethe-Heitler mechanism with final state interactions taken into account. The deuteron bound state is described by a relativistic covariant deuteron-nucleon vertex. With numerical results, we find that the differential cross section has strong dependence on the lepton azimuthal angle in the small polar angle region and sharp peaks appear in the dependence on the invariant mass of the produced lepton pair or the two nucleons in the final state. We demonstrate that such nearly singular feature originates from the collinearity between the produced lepton or antilepton and the incident photon, and it is physically regularized by the lepton mass in our calculation. The final state interaction between the knocked-out nucleon and the recoil nucleon redistributes the differential cross section over the missing momentum, with a significant enhancement at large missing momentum and a suppression in the intermediate region. With a further decomposition of the final state interaction contribution, it is found that the on-shell term dominates the near quasi-elastic region while the off-shell term dominates the other end. In addition, we examine the contribution from the interference between the proton amplitude and the neutron amplitude, which as expected is found negligible even if the proton-neutron rescattering is included. The result in this work can serve as an input for the analysis and background estimation of multiple exclusive measurements at Jefferson Lab and future electron-ion colliders.

    ↳ hep-phhep-exnucl-exnucl-thCPC(2024)·1 citation
  6. 08

    Odd-odd neutron-rich rhodium isotopes studied with the double Penning trap JYFLTRAP

    M. Hukkanen🇫🇮 · W. Ryssens🇧🇪 · P. Ascher🇫🇷 · M. Bender🇫🇷 · T. Eronen🇫🇮 · S. Grévy🇫🇷 · A. Kankainen🇫🇮 · M. Stryjczyk🇫🇮 · L. Al Ayoubi🇫🇮 · S. Ayet🇩🇪 · O. Beliuskina🇫🇮 · C. Delafosse🇫🇮 and 10 other authors

    Precision mass measurements of neutron-rich rhodium isotopes have been performed at the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. We report results on ground- and isomeric-state masses in Rh and the very first mass measurement of Rh. The isomeric states were separated and measured for the first time using the phase-imaging ion-cyclotron-resonance (PI-ICR) technique. For Rh, we also report new half-lives for both the ground state and the isomer. The results are compared to theoretical predictions using the BSkG1 mass model and discussed in terms of triaxial deformation.

    ↳ nucl-exnucl-thPRC(2023)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE