Tue·Dec 20, 2022Tuesday·December 20, 2022

1. 01*

   Topological features of the deconfinement transition

   Sz. Borsanyi🇩🇪 · Z. Fodor🇩🇪 · D.A. Godzieba🇺🇸 · R. Kara🇩🇪 · P. Parotto🇺🇸 · D. Sexty🇦🇹 · R. Vig🇩🇪

   The first order transition between the confining and the center symmetry breaking phases of the SU(3) Yang-Mills theory is marked by discontinuities in various thermodynamics functions, such as the energy density or the value of the Polyakov loop. We investigate the non-analytical behaviour of the topological susceptibility and its higher cumulant around the transition temperature and make the connection to the curvature of the phase diagram in the $T-\theta$ plane and to the latent heat.

   hep-latPRD(2023)·19 citations
2. 02*

   A lattice QCD study of the $B\to \pi \pi \ell \bar{\nu }$ transition

   Luka Leskovec🇸🇮 · Stefan Meinel🇺🇸 · Marcus Petschlies🇩🇪 · John Negele🇺🇸 · Srijit Paul🇬🇧 · Andrew Pochinsky🇺🇸 · Gumaro Rendon🇺🇸

   $V_{ub}$ is the smallest and least known of all CKM matrix elements; the community currently determines its magnitude primarily through the exclusive process $B\to \pi \ell \bar{\nu }$. Here we present our progress toward a lattice QCD determination of the $V_{ub}$ matrix element from a novel transition -- $B\to \pi \pi \ell \bar{\nu }$ process, where the $\pi \pi$ system is in a $P$ wave and scattering features the $\rho (770)$ resonance as an enhancement. We perform our calculation on $N_f=2+1$ isotropic clover fermions on a lattice of $L\approx 3.6$ fm and a pion mass of $\approx 320$ MeV; for the $b$-quark we use the anisotropic clover action. After a brief overview of the theoretical framework, we will discuss some preliminary results.

   hep-lathep-phPoS(2023)·16 citations
3. 03*

   Equation of state and speed of sound of (2+1)-flavor QCD in strangeness-neutral matter at non-vanishing net baryon-number density

   D. Bollweg🇺🇸 · D. A. Clarke🇺🇸 · J. Goswami🇯🇵 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · Swagato Mukherjee🇺🇸 · P. Petreczky🇺🇸 · C. Schmidt🇩🇪 · Sipaz Sharma🇩🇪

   We update results on the QCD equation of state in (2+1)-flavor QCD with non-zero conserved charge chemical potentials obtained from an eighth-order Taylor series. We present results for basic bulk thermodynamic observables of strangeness-neutral strong-interaction matter, i.e. pressure, number densities, energy and entropy density, and resum Taylor series results using Padé approximants. Furthermore, we calculate the speed of sound as well as the adiabatic compression factor of strangeness-neutral matter on lines of constant entropy per net baryon number. We show that the equation of state ($P(n_B),ϵ(n_B)$) is already well described by the $4^{\mathrm{th}}$-order Taylor series in almost the entire range of temperatures accessible with the beam energy scan in collider mode at the Relativistic Heavy Ion Collider.

   hep-lathep-phnucl-thPRD(2023)·75 citations
4. 04*

   Update on $SU(2)$ with one adjoint Dirac flavor

   Ed Bennett🇬🇧 · Andreas Athenodorou🇨🇾 · Georg Bergner🇩🇪 · Pietro Butti🇪🇸 · Biagio Lucini🇬🇧

   We present an update of our ongoing study of the SU(2) gauge theory with one flavor of Dirac fermion in the adjoint representation. Compared to our previous results we now have data at larger lattice volumes, smaller values of the fermion mass, and also larger values of $\beta$. We present data for the spectrum of mesons, baryons, glueballs, and the hybrid fermion-glue state, as well as new estimates of the mass anomalous dimension from both finite-size hyperscaling and the Dirac mode number, and discuss the implications of these data for the presence or otherwise of chiral symmetry breaking in this theory.

   hep-latPoS(2023)·6 citations
5. 05*

   The Compton amplitude and nucleon structure functions

   K. Utku Can🇦🇺

   Structure functions are the essential objects for understanding the deep inelastic scattering processes, providing valuable insight into the partonic structure of hadrons. A direct calculation of the Compton amplitude provides a complementary way to accessing the structure functions, circumventing the operator mixing and renormalisation issues of the standard operator product expansion approach. We describe the connection between the Compton amplitude and the structure functions, and describe a Feynman-Hellmann approach to calculate the amplitude directly. As an application, we extract the moments of transverse and longitudinal proton structure functions and study the power corrections.

   hep-lathep-phPoS(2023)·7 citations
6. 06*

   Progress applying density of states for gravitational waves

   Felix Springer🇬🇧 · David Schaich🇬🇧

   Many models of composite dark matter feature a first-order confinement transition in the early Universe, which would produce a stochastic background of gravitational waves that will be searched for by future gravitational-wave observatories. We present work in progress using lattice field theory to predict the properties of such first-order transitions. Targeting SU(N) Yang--Mills theories, this work employs the Logarithmic Linear Relaxation (LLR) density of states algorithm to avoid super-critical slowing down at the transition.

   hep-latEPJ Web Conf.(2022)·11 citations
7. 07*

   Lattice Study of Spectator Effects in $b$-hadron Decays

   Joshua Lin🇺🇸 · William Detmold🇺🇸 · Stefan Meinel🇺🇸

   The Heavy Quark Expansion (HQE) gives an expansion of inclusive decay rates of $b$-hadrons as a simultaneous series in ${\alpha }_s$ and $1/m_b$, in terms of perturbatively defined coefficients and non-perturbative matrix elements. Spectator effects arise from the dimension-$6$ operators in the HQE in which along with the heavy quark, a light spectator quark from the hadron participates in the weak decay. In this work, we provide a lattice determination of the bare matrix elements that contribute to the spectator effects for the $B^{+}$-meson, $B_d$-meson and the ${\Lambda }_b$-baryon. The computations were performed on two separate lattice spacings of the RBC-UKQCD (2+1)-flavor Domain Wall Fermion ensembles. Renormalization and continuum extrapolation of the matrix elements have not yet been computed, and are left to future work.

   hep-latPoS(2023)·11 citations
8. 08*

   Time windows of the muon HVP from twisted-mass lattice QCD

   C. Alexandrou · S. Bacchio · P. Dimopoulos · J. Finkenrath · R. Frezzotti · G. Gagliardi · M. Garofalo · K. Hadjiyiannakou · B. Kostrzewa · K. Jansen · V. Lubicz · M. Petschlies and 4 other authors

   We present a lattice determination of the leading-order hadronic vacuum polarization (HVP) contribution to the muon anomalous magnetic moment, $a_{\mu }^{\mathrm{HVP}}$, in the so-called short and intermediate time-distance windows, $a_{\mu }^{\mathrm{SD}}$ and $a_{\mu }^{\mathrm{W}}$. We employ gauge ensembles produced by the Extended Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ flavours of Wilson-clover twisted-mass quarks with masses of all the dynamical quark flavours tuned close to their physical values. The simulations are carried out at three values of the lattice spacing equal to $\simeq 0.057,0.068$ and $0.080$ fm with spatial lattice sizes up to $L\simeq 7.6$~fm. For the short distance window we obtain $a_{\mu }^{\mathrm{SD}}=69.27(34)\cdot 10^{-10}$, in agreement with the dispersive determination based on experimental $e^{+}{e}^{-}$ data. For the intermediate window we get instead $a_{\mu }^{\mathrm{W}}=236.3(1.3)\cdot 10^{-10}$, which is consistent with recent determinations by other lattice collaborations, but disagrees with the dispersive determination at the level of $3.6\sigma$.

   hep-lathep-phPoS(2023)·3 citations
9. 09*

   Charm baryons at finite temperature on anisotropic lattices

   Ryan Bignell🇬🇧 · Gert Aarts🇬🇧 · Chris Allton🇬🇧 · M. Naeem Anwar🇬🇧 · Timothy J. Burns🇬🇧 · Benjamin Jäger🇩🇰

   Singly, doubly and triply charmed baryons are investigated at multiple temperatures using the anisotropic FASTSUM 'Generation 2L' ensembles. We discuss the temperature dependence of these baryons' spectra in both parity channels with a focus on the confining phase. To further qualify the behaviour of these states around the pseudocritical temperature, we investigate the effect of chiral symmetry restoration for light quarks. We find that an estimate of the pseudocritical temperature can still be found from positive and negative-parity charmed baryon correlators, even when parity doubling itself is not very evident (as expected).

   hep-latPoS(2023)·2 citations
10. 10*

    Optimized meson operators for charmonium spectroscopy and mixing with glueballs

    Juan Andrés Urrea-Niño🇩🇪 · Francesco Knechtli🇩🇪 · Tomasz Korzec🇩🇪 · Michael Peardon🇮🇪

    Optimized meson operators in the distillation framework are used to study the charmonium spectrum in two ensembles with two heavy dynamical quarks at half the physical charm quark mass but different lattice spacings. The use of optimal meson distillation profiles is shown to increase the overlap with the ground state significantly, as well as grant access to excited states, for multiple quantum numbers including hybrid states with very little additional cost. These same operators are also employed for the calculation of meson-glueball mixing.

    hep-latPoS(2023)·5 citations
11. 11*

    Position-Space Renormalisation of the Energy-Momentum Tensor

    Henrique Bergallo Rocha🇬🇧 · Luigi Del Debbio🇬🇧 · Andreas Jüttner🇬🇧 · Ben Kitching-Morley🇬🇧 · Joseph K. L. Lee🇬🇧 · Antonin Portelli🇬🇧 · Kostas Skenderis🇬🇧

    There is increasing interest in the study of nonperturbative aspects of three-dimensional quantum field theories (QFT). They appear as holographic dual to theories of (strongly coupled) gravity. For instance, in Holographic Cosmology, the two-point function of the Energy-Momentum Tensor (EMT) of a particular class of three-dimensional QFTs can be mapped into the power spectrum of the Cosmic Microwave Background in the gravitational theory. However, the presence of divergent contact terms poses challenges in extracting a renormalised EMT two-point function on the lattice. Using a ${\varphi }^4$ theory of adjoint scalars valued in the $\mathfrak{su}(N)$ Lie Algebra as a proof-of-concept motivated by Holographic Cosmology, we apply a novel method for filtering out such contact terms by making use of infinitely differentiable "bump" functions which enforce a smooth window that excludes contributions at zero spatial separation. The process effectively removes the local contact terms and allows us to extract the continuum limit behaviour of the renormalised EMT two-point function.

    hep-latPoS(2023)·2 citations
12. 12*

    Digitizing SU(2) Gauge Fields and What to Look Out for When Doing So

    Tobias Hartung🇬🇧 · Timo Jakobs🇩🇪 · Karl Jansen🇩🇪 · Johann Ostmeyer🇬🇧 · Carsten Urbach🇩🇪

    With the long term perspective of using quantum computers and tensor networks for lattice gauge theory simulations, an efficient method of digitizing gauge group elements is needed. We thus present our results for a handful of discretization approaches for the non-trivial example of SU(2), such as its finite subgroups, as well as different classes of finite subsets. We focus our attention on a freezing transition observed towards weak couplings. A generalized version of the Fibonacci spiral appears to be particularly efficient and close to optimal.

    hep-latphysics.comp-phquant-phPoS(2023)·3 citations
13. 13*

    Translating topological benefits in very cold lattice simulations

    Mattia Bruno🇮🇹 · Marco Cè🇨🇭 · Anthony Francis🇹🇼 · Jeremy R. Green🇩🇪 · Max Hansen🇬🇧 · Savvas Zafeiropoulos🇫🇷

    Master-field simulations offer an approach to lattice QCD in which calculations are performed on a small number of large-volume gauge-field configurations. The latter is advantageous for simulations in which the global topological charge is frozen due to a very fine lattice spacing, as the effect of this on observables is suppressed by the spacetime volume. Here we make use of the recently developed Stabilised Wilson Fermions to investigate a variation of this approach in which only the temporal direction ($T$) is taken larger than in traditional calculations. As compared to a hyper-cubic lattice geometry, this has the advantage that finite-$L$ effects can be useful, e.g. for multi-hadron observables, while compared to open boundary conditions, time-translation invariance is not lost. In this proof-of-concept contribution, we study the idea of using very cold (i.e. long-$T$) lattices to topologically "defrost" observables at fine lattice spacing. We identify the scalar-scalar meson two-point correlation function as a useful probe and present first results from $N_f=3$ ensembles with time extents up to $T=2304$ and a lattice spacing of $a=0.055\mathrm{fm}$.

    hep-latPoS(2023)·3 citations
14. 14*

    Finite-Size Effects of the HVP Contribution to the Muon $g-2$ with C${}^{\star }$ Boundary Conditions

    Sofie Martins🇩🇰 · Agostino Patella🇩🇪

    The muon $g-2$ is a compelling quantity due to the current standing tensions among the experimental average, data-driven theoretical results, and lattice results. Matching the final target accuracy of the experiments at Fermilab and J-PARC will constitute a major challenge for the lattice community in the coming years. For this reason, it is worthwhile to consider different options to keep the systematic errors under control. In this proceedings, we discuss finite-volume effects of the leading Hadron Vacuum Polarization (HVP) contribution to the muon $g-2$ in the presence of C${}^{\star }$ boundary conditions. When considering isospin-breaking corrections to the HVP, C${}^{\star }$ boundary conditions provide a possible consistent formulation of $\mathrm{QCD}+\mathrm{QED}$ in finite volume. Even though these boundary conditions can be avoided in the calculation of the leading HVP contribution, we find the interesting result that they remove the leading exponential finite-volume correction. In practice, compared to the periodic case, C${}^{\star }$ boundary conditions cut the finite-size effects in half on a lattice of physical size $M_{\pi }L=4$ and by a factor of almost ten for $M_{\pi }L=8$. We discuss the origin of this reduction and implications for computational efficiency.

    hep-latPoS(2023)·4 citations
15. 15*

    $N_f=1+2+1$ QCD+QED simulations with C${}^{\star }$ boundary conditions

    Anian Altherr🇨🇭 · Lucius Bushnaq🇮🇪 · Isabel Campos🇪🇸 · Marco Catillo🇨🇭 · Alessandro Cotellucci🇩🇪 · Madeleine Dale🇩🇪 · Patrick Fritzsch🇮🇪 · Roman Gruber🇨🇭 · Jens Lücke🇩🇪 · Marina Krstić Marinković🇪🇸 · Agostino Patella🇩🇪 · Nazario Tantalo🇮🇹 · Paola Tavella🇨🇭

    We give an update on the ongoing effort of the RC${}^{\star }$ collaboration to generate fully dynamical QCD+QED configurations with C${}^{\star }$ boundary conditions using the openQ${}^{\star }$D code. The simulations are tuned to the U-symmetric point ($m_d=m_s$) with pions at $m_{{\pi }^{\pm }}\approx 400$ MeV. The splitting of the light mesons is used as one of three tuning observables and fixed to $m_{K^0}-m_{K^{\pm }}\approx 5$ MeV and $m_{K^0}-m_{K^{\pm }}\approx 25$ MeV on ensembles with renormalized electromagnetic coupling ${\alpha }_{\mathrm{R}}\approx {\alpha }_{phys.}$ and ${\alpha }_{\mathrm{R}}\approx 5.5{\alpha }_{phys.}$ respectively. We will discuss some details concerning our tuning strategy and present the calculation of the meson and baryon masses. Finally, we will also present a cost analysis for our simulations. More technical details on finite-volume effects and the tuning can be found in A. Cotellucci's proceedings.

    hep-latPoS(2023)·3 citations
16. 16*

    Nucleon-nucleon scattering from distillation

    Jeremy R. Green🇩🇪 · Andrew D. Hanlon🇺🇸 · Parikshit M. Junnarkar🇩🇪 · Hartmut Wittig (for the Baryon Scattering (BaSc) collaboration)🇩🇪

    We report an ongoing analysis of nucleon-nucleon scattering based on finite-volume spectroscopy. The calculation is performed using the distillation method on eight lattice ensembles at the SU(3)-symmetric point with $m_{\pi }=m_K\approx 420$ MeV generated by CLS, covering a range of lattice spacings and volumes and previously used to study the $H$ dibaryon. We obtain nonzero signals for $S$, $P$, $D$, and $F$ waves as well as the mixing between spin-1 $S$ and $D$ waves. For $S$ waves, lattice artifacts are significant and tend to strengthen baryon-baryon interactions. In the deuteron and dineutron $S$ waves, we find virtual bound states.

    hep-latPoS(2023)·12 citations
17. 17*

    Towards the phase diagram of cold and dense heavy QCD

    Amine Chabane🇩🇪 · Owe Philipsen🇩🇪

    The thermodynamics of QCD with sufficiently heavy dynamical quarks can be described by a three-dimensional Polyakov loop effective theory, obtained after a truncated character and hopping expansion. We investigate the resulting phase diagram for low temperatures by mean field methods. Taking into account chemical potentials for both baryon number and isospin, we obtain clear signals for a liquid-gas type transition to baryon matter at ${\mu }_I=0$ and a Bose-Einstein condensation transition at ${\mu }_B=0$, as well as for their connection when both chemical potentials are non-zero.

    hep-latPoS(2023)·2 citations
18. 18*

    Progress on the exploratory calculation of the rare Hyperon decay ${\Sigma }^{+}\to p{\ell }^{+}{\ell }^{-}$

    Felix Erben🇬🇧 · Vera Gülpers🇬🇧 · Maxwell T. Hansen🇬🇧 · Raoul Hodgson🇬🇧 · Antonin Portelli🇬🇧

    The rare Hyperon decay ${\Sigma }^{+}\to p{\ell }^{+}{\ell }^{-}$ is an $s\to d$ flavour changing neutral current process, which is highly suppressed within the Standard Model, and is therefore sensitive to new physics. Due to recent improvements in experimental measurements of this decay, the Standard Model theory prediction must also be improved in order to identify any new physics in this channel. We present updates on our progress towards the first exploratory lattice calculation of the long-distance part of the form factors of this decay. This pilot calculation is performed on a 340 MeV pion mass ensemble using domain-wall fermions as part of the RBC-UKQCD collaboration.

    hep-latPoS(2023)·4 citations
19. 19*

    Asymptotic lattice spacing dependence of spectral quantities in lattice QCD with Wilson or Ginsparg-Wilson quarks

    Nikolai Husung🇬🇧

    One major systematic uncertainty of lattice QCD results is due to the continuum extrapolation. For an asymptotically free theory like QCD one finds corrections of the form $a^{n_{\min }}[2b_0{\bar{g}}^2(1/a){]}^{{\hat{\Gamma }}_i}$ with lattice spacing $a$, where $\bar{g}(1/a)$ is the running coupling at renormalisation scale $\mu =1/a$ and $n_{\min }$ is a positive integer. ${\hat{\Gamma }}_i$ can take any positive or negative value, but is computable by next-to-leading order perturbation theory. It will impact convergence towards the continuum limit. Balog, Niedermayer and Weisz first pointed out how problematic such corrections can be in their seminal work for the O(3) model. Based on Symanzik Effective Theory for lattice QCD with Ginsparg-Wilson and Wilson quarks, various powers ${\hat{\Gamma }}_i$ are found due to lattice artifacts from the discretised lattice action. Those powers are sufficient when describing spectral quantities, while non-spectral quantities will require additional powers originating from corrections to each of the discretised local fields involved. This new input should be incorporated into ansätze used for the continuum extrapolation.

    hep-latPoS(2023)·1 citation
20. 20*

    Hamiltonian limit of lattice QED in 2+1 dimensions

    L. Funcke🇩🇪 · C. F. Groß🇩🇪 · K. Jansen🇩🇪 · S. Kühn🇩🇪 · S. Romiti🇩🇪 · C. Urbach🇩🇪

    The Hamiltonian limit of lattice gauge theories can be found by extrapolating the results of anisotropic lattice computations, i.e., computations using lattice actions with different temporal and spatial lattice spacings ($a_t\ne a_s$), to the limit of $a_t\to 0$. In this work, we present a study of this Hamiltonian limit for a Euclidean $U(1)$ gauge theory in 2+1 dimensions (QED3), regularized on a toroidal lattice. The limit is found using the renormalized anisotropy ${\xi }_R=a_t/a_s$, by sending ${\xi }_R\to 0$ while keeping the spatial lattice spacing constant. We compute ${\xi }_R$ in $3$ different ways: using both the ``normal'' and the ``sideways'' static quark potential, as well as the gradient flow evolution of gauge fields. The latter approach will be particularly relevant for future investigations of combining quantum computations with classical Monte Carlo computations, which requires the matching of lattice results obtained in the Hamiltonian and Lagrangian formalisms.

    hep-latquant-phPoS(2023)·9 citations
21. 21*

    Monopole and instanton effects on connected and disconnected correlations for scalar density

    Masayasu Hasegawa🇷🇺

    This study investigates the effects on the connected and disconnected correlations for the scalar density that are induced by created monopoles and instantons in the QCD vacuum. To reveal the effects, we add a monopole and anti-monopole pair in the gauge field configurations in \textit{SU}(3) by applying the monopole creation operator to the vacuum. We vary the magnetic charges of the monopole and anti-monopole and increase the number of monopoles and anti-monopoles in the configurations. The Dirac operator of overlap fermions preserves the exact chiral symmetry in lattice gauge theory and exact zero-modes exist in its spectrum. The eigenvalues and eigenvectors of the overlap Dirac operator have been calculated using these configurations, and the numbers of instantons and anti-instantons which are created by these additional monopoles and anti-monopoles have been estimated from the numbers of topological charges in our previous studies. In this study, we demonstrate the preliminary results that instantons and monopoles influence the masses that are evaluated from the connected and disconnected correlation functions for the scalar density using low-lying eigenvalues and eigenvectors of the overlap Dirac operator.

    hep-lathep-phnucl-thPhys.Atom.Nucl.(2023)·0 citations
22. 22*

    LapH interpolating fields with open boundary conditions

    Michele Della Morte🇩🇰 · Olmo Francesconi🇩🇰 · Justus Tobias Tsang🇨🇭

    The stochastic Laplacian Heaviside (LapH) method has proven to be successful in hadronic calculations. In this work, with charm-light spectroscopy in mind, we set up and optimise the LapH procedure limiting ourselves to the evaluation of two-point mesonic correlation functions. The calculations are performed on CLS ensembles with $N_f=2+1$ Wilson-Clover fermions on a $32^3\times 64$ lattice with open boundary conditions. We analyse the interplay between the LapH parameters and the boundary effects, and implement a fitting procedure to isolate excitations coming from the border.

    hep-latPoS(2023)·0 citations
23. 23*

    Nucleon resonances and transition form factors

    Volker D. Burkert🇺🇸

    This is a contribution to the review 50 Years of Quantum Chromodynamics edited by F. Gross and E. Klempt, to be published in Journal EPJC. This contribution reviews the nucleon resonance transition form factors determined from meson electro-production experiments at electron accelerator facilities, i.e. this contribution focuses on space-like transition form factors and amplitudes. Comparisons are made when available to LQCD and to approaches with traceable links to strong QCD and to advanced quark model calculations

    ↳ hep-phhep-latnucl-ex9 citations
24. 24*

    Heavy hybrid decays to quarkonia

    Nora Brambilla🇩🇪 · Wai Kin Lai🇨🇳 · Abhishek Mohapatra🇩🇪 · Antonio Vairo🇩🇪

    The decay rates of the XYZ exotics discovered in the heavy quarkonium sector are crucial observables for identifying the nature of these states. Based on the framework of nonrelativistic effective field theories, we calculate the rates of semi-inclusive decays of heavy quarkonium hybrids into conventional heavy quarkonia. We compute them at leading and subleading power in the inverse of the heavy-quark mass, extending and updating previous results. We compare our predictions with experimental data of inclusive decay rates for candidates of heavy quarkonium hybrids.

    ↳ hep-phhep-exhep-latPRD(2023)·32 citations
25. 25*

    Kaon physics overview

    Jason Aebischer🇨🇭

    The present status of Kaon physics is summarized from a theory point of view. Focus is laid on $\Delta S=2$, $\Delta S=1$ as well as on rare Kaon decays, where progress has been made for instance in the case of ${\epsilon }_K$ and $K_S\to {\mu }^{+}{\mu }^{-}$. Furthermore, several New Physics scenarios are discussed in the context of rare Kaon decays and other Kaon observables.

    ↳ hep-phhep-exhep-latJ.Phys.Conf.Ser.(2023)·2 citations
26. 26*

    Anisotropic fluctuations of angular momentum of heavy quarks in the Glasma

    Pooja🇮🇳 · Santosh K. Das🇮🇳 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹

    We study the evolution of the angular momentum of the heavy quarks in the very early stage of high energy nuclear collisions, in which the background is made of evolving Glasma fields. Given the novelty of the problem, we limit ourselves to the use of toy heavy quarks with a large, unphysical mass, in order to implement the kinetic equations for the angular momentum in the non-relativistic limit. We find that as a consequence of the anisotropy of the background fields, angular momentum fluctuations are also anisotropic: we understand this in simple terms relating the fluctuations of the angular momentum, $L$, to those of linear momentum. While orbital angular momentum diffuses and develops substantial fluctuations and anisotropies, the spin does not. Hence, we can identify the fluctuations of $L$ with those of the total angular momentum $J=L+S$. Therefore, our study suggests that the total angular momentum of the heavy quarks in the early stage of high energy nuclear collisions will present anisotropic fluctuations.

    ↳ hep-phhep-latnucl-thEur.Phys.J.Plus(2023)·18 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.