PaperPanorama

HEP Lattice·hep-lat

Wed·Aug 26, 2026

7 papers—1 primary·6 cross-listed

All7Primary1Cross-lists6
  1. 01

    Direct lattice QCD calculation of the -induced CP-violating pion-nucleon coupling

    Chuan-Yang Li🇨🇳 · Jun Hua🇨🇳 · Jian Liang🇨🇳 · Keh-Fei Liu🇺🇸 · Long-cheng Gui🇨🇳 · Jun Shi🇨🇳 · Nan Wang🇨🇳

    We present the first direct lattice QCD determination of the -induced CP-violating pion-nucleon-nucleon coupling . Using overlap valence fermions on three -flavor domain-wall ensembles at a single lattice spacing, we calculate the forward proton matrix element of the isovector pseudoscalar density in the -vacuum to first order in . The parity-mixing effect in the external nucleon states is included in the extraction. The cluster-decomposition error-reduction method is used to improve the statistical precision. A simultaneous extrapolation in the valence- and sea-pion masses, with model averaging over 7 forms based on the Akaike information criterion, gives at the physical point. The first uncertainty includes the statistical and matrix-element-fit systematic uncertainties, whereas the second reflects the spread among the extrapolation forms. Within these uncertainties, the result is consistent with the indirect determination based on the strong neutron-proton mass splitting. The present precision is limited primarily by the extrapolation from the relatively heavy sea-pion masses.

    hep-lathep-ph1 citation
  2. 02

    Cluster Representation of Renormalization Group Transformations and a Rigorous Proof for Convergence of the RG-Flow of the Ising Model to Trivial Fixed Points away from Criticality

    Fabio Arz

    Many rigorous results in the modern era of statistical mechanics have been obtained through geometrical representations. A much studied tool in this setting is the random cluster representation of lattice spin models. Another area of statistical mechanics that is of great interest but lacking rigorous results is the theory of the renormalization group. This paper investigates the idea to find a common ground between these two concepts in order to obtain rigorous results on the renormalization group flow. A need for negative cluster-weights weakens the success of this approach. Nevertheless, we managed to establish a relation between the scaling limit of the renormalization group flow of the nearest-neighbour Ising model away from criticality with a simple one-dimensional dynamical system that follows the cluster connectivity of the renormalization group transformation. This allows for a rigorous proof of the convergence of this flow to the zero- and infinite-temperature fixed point respectively for a large family of renormalization group transformations. Explicit results will be established on followed by a discussion of the available generalizations to higher dimensions.

    ↳ math-phcond-mat.stat-mechhep-latmath.MP0 citations
  3. 03

    Non-perturbative news from the conformal window

    Álvaro Pastor-Gutiérrez🇯🇵

    Dynamical symmetry breaking plays a crucial role in mass and scale generation. In QCD-like theories, its dependence on the number of fermion flavours determines the phase structure and the transition to the conformal regime. In this work, we employ the functional renormalisation group and the generalised flow equation to compute non-perturbative corrections, including momentum dependencies and field invariants essential for an adequate realisation of the global symmetry. As a consequence, the critical gauge coupling required for dynamical chiral symmetry breaking acquires a strong dependence on the number of flavours and increases sharply at for . This establishes a new picture of the conformal phase transition that challenges Miransky/BKT scaling and the existence of walking regimes, favours a first-order quantum phase transition, and points towards a critical region with exotic dynamics and symmetric fermion mass gaps.

    ↳ hep-thhep-lathep-ph0 citations
  4. 04

    Femtoscale imaging of the proton with Ioffe-time distributions

    Robert G. Edwards🇺🇸 · Joe Karpie🇺🇸 · Christopher Monahan🇺🇸 · Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · David Richards🇺🇸 · Eloy Romero🇺🇸 · Savvas Zafeiropoulos🇫🇷

    Mapping how strongly interacting constituents are distributed within protons is a key goal of nuclear physics and a major direction of the future Electron Ion Collider program. We propose a novel space-time description of hadron structure in terms of impact-parameter Ioffe-time distributions, relating spatial density in the plane transverse to the proton momentum and the time between the probe's absorption and the product's emission in the longitudinal direction. Using lattice Quantum Chromodynamics, we perform the first calculation of the Ioffe-time-dependent mean squared proton radii and compare our results with estimates in the Goloskokov-Kroll model. We derive a relationship between the experimentally measurable Compton form factor and the generalized Ioffe-time distribution, which allows us to perform the first extraction of the Compton form factor from lattice calculations.

    ↳ hep-phhep-latnucl-th0 citations
  5. 05

    Photon and gluon gravitational form factors of proton in QCD

    Z. Asmaee🇮🇷 · K. Azizi🇮🇷

    The energy-momentum tensor provides a unique insight into the internal gravitational structure of the proton by revealing how energy, momentum, and mechanical properties are distributed among its different QCD components. The gravitational form factors associated with different components of the QCD energy-momentum tensor allow us to investigate the individual contributions of these sectors to the gravitational properties of the proton. In this work, we calculate the photon and gluon gravitational form factors of the proton within the framework of QCD sum rules. Using the photon and gluon components of the QCD energy-momentum tensor, we derive the corresponding sum rules for four independent gravitational form factors. Their momentum transfer dependence is analyzed within the validity region of the method and extrapolated to zero momentum transfer using a multipole parametrization. The resulting parametrizations of the form factors are used to extract the mass and scalar radii associated with the photon and gluon sectors. Our results indicate that the gluon mass radius is smaller than the photon mass radius, suggesting a more localized gluonic energy distribution inside the proton. These findings provide new nonperturbative information on the gravitational structure of the proton and offer complementary theoretical results for future lattice QCD calculations and phenomenological studies.

    ↳ hep-phhep-exhep-lat0 citations
  6. 06

    The fate of chiral symmetry in two-flavor matrix adjoint QCD

    Nirmalendu Acharyya🇮🇳 · Prasanjit Aich🇮🇳 · Sayan Bhakta🇮🇳 · Ranita Mudi🇮🇳 · Sachindeo Vaidya🇮🇳

    In the matrix model of two-flavor adjoint QCD, we study the low-lying states and their properties in the intermediate-to-strong (Yang-Mills) coupling regime. The model has a classical chiral symmetry and the eigenstates of the Hamiltonian can be organized in its irreps. We construct the energy eigenstates in presence of a chiral chemical potential using the variational techniques. We find that when , the ground state is always a singlet, irrespective of the coupling strength . However, as is tuned from intermediate to strong coupling, the system under goes a crossover from a unique to a doubly degenerate ground state. The degeneracy in the strong coupling regime spontaneously breaks the axial , while preserving the chiral symmetry. When , we find that there can be level crossings which correspond to quantum phase transitions (QPTs). Depending on the ground state, there are three possible phases. The symmetry is spontaneously broken in only one of these phases, and this phase can only emerge for intermediate with moderate values of . In the plane this phase corresponds to a narrow window, outside which is always preserved.

    ↳ hep-thhep-lathep-ph0 citations
  7. 07

    Probing Dirac Dark Matter in Composite Higgs Models with Xenon and Argon targets

    M. G. Belyakova🇷🇺 · R. Nevzorov🇷🇺

    Recent advancements in direct detection (DD) experiments stimulate the investigation of the interactions of dark matter (DM) with nucleons and nuclei. In the framework of Composite Higgs Models (CHMs) the lightest Dirac composite particle (LDCP) can be stable composing a significant fraction \xi of the observed DM relic abundance. We consider the elastic scattering of the LDCP on nucleons as well as on xenon (Xe) and argon (Ar) nuclei within the CHMs in which the LDCP magnetic moment, its mass and its coupling to the Higgs doublet are suppressed by an approximate U(1) symmetry. The LDCP with non-zero magnetic dipole moment can result in a substantial enhancement of the differential event rate in the DD experiments at low recoil energies of nuclei. Assuming \xi\ge 0.1, we identify the region of the parameter space where such enhancement may be potentially observable. In addition we specify some observables that can be useful in discriminating between the DM fermions with non-zero magnetic moment and other types of dark matter particles which don't have similar electromagnetic properties.

    ↳ hep-phgr-qchep-exhep-lat+10 citations

Affiliations

first authorsco-authorsvia INSPIRE