Thu·Feb 29, 2024Thursday·February 29, 2024

1. 01*

   Weak scale supersymmetry emergent from the string landscape

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dakotah Martinez🇺🇸 · Shadman Salam🇧🇩

   Superstring flux compactifications can stabilize all moduli while leading to an enormous number of vacua solutions, each leading to different $4-d$ laws of physics. While the string landscape provides at present the only plausible explanation for the size of the cosmological constant, it may also predict the form of weak scale supersymmetry which is expected to emerge. Rather general arguments suggest a power-law draw to large soft terms, but these are subject to an anthropic selection of not-too-large a value for the weak scale. The combined selection allows one to compute relative probabilities for the emergence of supersymmetric models from the landscape. Models with weak scale naturalness appear most likely to emerge since they have the largest parameter space on the landscape. For finetuned models such as high scale SUSY or split SUSY, the required weak scale finetuning shrinks their parameter space to tiny volumes, making them much less likely to appear compared to natural models. Probability distributions for sparticle and Higgs masses from natural models show a preference for Higgs mass $m_h\sim 125$ GeV with sparticles typically beyond present LHC limits, in accord with data. From these considerations, we briefly describe how natural SUSY is expected to be revealed at future LHC upgrades. This article is a contribution to the Special Edition of the journal {\it Entropy} honoring Paul Frampton on his 80th birthday.

   hep-phhep-thEntropy(2024)·5 citations
2. 02*

   Nucleons and vector mesons in a confining holographic QCD model

   Alfonso Ballon-Bayona🇧🇷 · Adão S. da Silva Junior🇧🇷

   We present a simple holographic QCD model that provides a unified description of vector mesons and nucleons in a confining background based on Einstein-dilaton gravity. For the confining background we consider analytical solutions of the Einstein-dilaton equations where the dilaton is a quadratic function of the radial coordinate far from the boundary. We build actions for the 5d gauge field and the 5d Dirac field dual to the 4d flavor current and the 4d nucleon interpolator respectively. In order to obtain asymptotically linear Regge trajectories we impose for each sector the condition that the effective Schrödinger equation has a potential that grows quadratically in the radial coordinate far from the boundary. For the vector mesons we show that this condition is automatically satisfied by a 5d Yang-Mills action minimally coupled to the metric and the dilaton. For the nucleons we find that the mass term of the 5d Dirac action needs to be generalised to include couplings to the metric and the dilaton. Using Sturm-Liouville theory we obtain a spectral decomposition for the hadronic correlators consistent with large $N_c$ QCD. Our setup contains only three parameters: the mass scale associated with confinement, the 5d gauge coupling and the 5d Dirac coupling. The last two are completely fixed by matching the correlators at high energies to perturbative QCD. We calculate masses and decay constants and compare our results against available experimental data. Our model can be thought of as a consistent embedding of soft wall models in Einstein-dilaton gravity.

   hep-phhep-thPRD(2024)·6 citations
3. 03*

   All-heavy pentaquarks

   Zhi-Biao Liang🇨🇳 · Feng-Xiao Liu🇨🇳 · Xian-Hui Zhong🇨🇳

   In a nonrelativistic potential quark model framework, we carry out a calculation of the mass spectrum for the low-lying $1S$ all-heavy pentaquark state by adopting the explicitly correlated Gaussian method. The obtained states are compact and lie far above the lowest dissociation baryon-meson threshold. Moreover, using the obtained masses and wave functions we evaluate the fall-apart decay properties within a quark-exchange model. The results show that the $1S$ all-heavy pentaquark states have a fairly narrow fall-apart width, which scatters in the range of $\sim 0.1-4.0$ MeV. Their dominant fall-apart decay channels may be ideal for searching for their signals in future experiments.

   hep-phhep-exPRD(2025)·13 citations
4. 04*

   Collisional energy loss of a heavy quark in a semiquark-gluon plasma

   Qianqian Du🇨🇳 · Mudong Du🇨🇳 · Yun Guo🇨🇳

   By utilizing a background field effective theory, we compute the collisional energy loss of a heavy quark moving through a semiquark-gluon plasma characterized by nontrivial holonomy for Polyakov loops. We consider the elastic scatterings between the incident heavy quark and the thermal partons with both hard and soft momentum transfers. As compared to the energy loss obtained from the perturbation theory, the hard processes get modified through the thermal distribution functions that depend on the background field, while the proper treatment of the soft processes strongly relies on the use of the hard-thermal-loop resummed gluon propagator derived from the background field effective theory. Our results show that the heavy quark energy loss is significantly suppressed in the semiquark-gluon plasma due to a background field that is self-consistently generated in the effective theory. On the other hand, the suppression has a strong dependence on the temperature of the plasma which becomes negligible above $2-3$ times the critical temperature. For a realistic coupling constant, ignoring a relatively weak dependence on the heavy quark velocity, the suppression on the collisional energy loss can be approximated by an overall factor determined solely by the background field. This simple conclusion is expected to be useful for phenomenological applications in the heavy flavor physics.

   hep-phnucl-thPRD(2024)·11 citations
5. 05*

   Ultra-light Dark Matter Search with Astrophysical Neutrino Flavour

   Carlos A. Argüelles🇺🇸 · Kareem Farrag🇯🇵 · Teppei Katori🇬🇧

   The ultra-light dark matter is a new class of dark matter candidates. Unlike traditional dark matter particle candidates, the ultra-light dark matter behaves like a classical field, which saturates the entire Milky Way galaxy with a coherent oscillation. If such dark matter exists and couples with neutrinos, properties of astrophysical neutrinos propagating in the Milky Way would be modified and detectable by neutrino telescopes such as IceCube. Meantime, IceCube looked for quantum-gravity-motivated effects from the astrophysical neutrino flavour information. IceCube did not find evidence of new physics, and they set limits on neutrino - Lorentz violating field couplings. Here, we investigate if these results can be applied to limit the ultra-light dark matter couplings with neutrinos. It is found that the strong limits of neutrino-dark matter couplings in low dark matter mass regions can be obtained in this approach.

   hep-phPoS(2023)·8 citations
6. 06*

   Photon quantum kinetic equations and collective modes in an axion background

   Marc Comadran🇪🇸 · Cristina Manuel🇪🇸

   We develop a quantum kinetic theory for photons in the presence of an axion background and in the collisioness limit. In deriving the classical regime of our quantum kinetic equations, we observe that they capture well known features of axion electrodynamics. By projecting the Wigner function onto a polarization basis, relating the Wigner matrix function with the Stokes parameters, we establish the dispersion relations and transport equations for each polarization space component. Additionally, we investigate how the axion background affects the dispersion relations of photon collective modes within an electron-positron plasma at equilibrium temperature $T$. While the plasmon remains unaffected, we find that the axion background breaks the degeneracy of transverse collective modes at order $e{g}_{a\gamma }T(\partial a)$, where $e$ represents the electron charge, $g_{a\gamma }$ denotes the photon-axion coupling, and $\partial a$ represents the scale associated with variations in the axion field.

   hep-phPRD(2024)·4 citations
7. 07*

   Imprints of new physics operators in the semileptonic $B\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$ process in SMEFT approach

   Manas Kumar Mohapatra🇮🇳 · Dhiren Panda🇮🇳 · Rukmani Mohanta🇮🇳

   At present, there are several measurements of $B$ decays that exhibit discrepancies with the predictions of the Standard Model, and suggest the presence of new physics in $b\to s$ and $b\to c(u)$ quark level transitions. Motivated by the prospects of the ongoing high-luminosity $B$ factories, we study the exclusive $B\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$ process within the Standard Model Effective Field Theory (SMEFT) formalism, to understand the sensitivity of new physics. The new physics parameters are constrained by using the experimental branching fractions of the (semi)leptonic $B\to \ell \bar{\nu }$ and $B\to (\pi ,\rho ,\omega )\ell \bar{\nu }$ processes (where $\ell =e,\mu ,\tau$) which undergo $b\to u\ell \bar{\nu }$ quark level transitions. We then perform a comprehensive angular analysis of the exclusive $B\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$ process in the Standard Model and in the presence of various new physics operators. We also provide the predictions and comment on various observables, such as branching ratio, forward-backward asymmetry, and the test of lepton flavor non universality of the $B\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$ channel.

   hep-phPLB(2024)·6 citations
8. 08*

   Prospects for measuring time variation of astrophysical neutrino sources at dark matter detectors

   Yi Zhuang🇺🇸 · Louis E. Strigari🇺🇸 · Lei Jin🇬🇧 · Samiran Sinha🇺🇸

   We study the prospects for measuring the time variation of solar and atmospheric neutrino fluxes at future large-scale Xenon and Argon dark matter detectors. For solar neutrinos, a yearly time variation arises from the eccentricity of the Earth's orbit, and, for charged current interactions, from a smaller energy-dependent day-night variation to due flavor regeneration as neutrinos travel through the Earth. For a 100-ton Xenon detector running for 10 years with a Xenon-136 fraction of $\lesssim 0.1\%$, in the electron recoil channel a time-variation amplitude of about 0.8\% is detectable with a power of 90\% and the level of significance of 10\%. This is sufficient to detect time variation due to eccentricity, which has amplitude of $\sim 3\%$. In the nuclear recoil channel, the detectable amplitude is about 10\% under current detector resolution and efficiency conditions, and this generally reduces to about 1\% for improved detector resolution and efficiency, the latter of which is sufficient to detect time variation due to eccentricity. Our analysis assumes both known and unknown periods. We provide scalings to determine the sensitivity to an arbitrary time-varying amplitude as a function of detector parameters. Identifying the time variation of the neutrino fluxes will be important for distinguishing neutrinos from dark matter signals and other detector-related backgrounds, and extracting properties of neutrinos that can be uniquely studied in dark matter experiments.

   hep-phastro-ph.HEPRD(2024)·5 citations
9. 09*

   Z' boson mass reach and model discrimination at muon colliders

   Kateryna Korshynska🇩🇪 · Maximilian Löschner🇩🇪 · Mariia Marinichenko🇳🇱 · Krzysztof Mękała🇩🇪 · Jürgen Reuter🇩🇪

   We study the discrimination power of future multi-TeV muon colliders for a large set of models with extended gauge symmetries and additional neutral gauge bosons ("$Z^{\prime }$-models"). Our study is carried out using a ${\chi }^2$-analysis of leptonic observables of s-channel scattering in effective $Z^{\prime }$-models. We make use of angular and chiral asymmetries induced in such models to find the discovery reach of a given muon collider setup in terms of the $Z^{\prime }$ mass and to discriminate between the different scenarios. In this context, we discuss how polarized beams - should they become available at muon colliders - or polarization measurements can help in the discrimination. Our results show that typical muon collider setups which are currently under consideration can give a significantly higher reach compared to existing bounds and projections for high-luminosity LHC.

   hep-phEPJC(2024)·21 citations
10. 10*

    Towards a precision calculation of $N_{\mathrm{eff}}$ in the Standard Model III: Improved estimate of NLO contributions to the collision integral

    Marco Drewes🇧🇪 · Yannis Georis🇧🇪 · Michael Klasen🇩🇪 · Luca Paolo Wiggering🇩🇪 · Yvonne Y. Y. Wong🇦🇺

    We compute the dominant QED correction to the neutrino-electron interaction rate in the vicinity of neutrino decoupling in the early universe, and estimate its impact on the effective number of neutrino species $N_{\mathrm{eff}}$ in cosmic microwave background anisotropy observations. We find that the correction to the interaction rate is at the sub-percent level, consistent with a recent estimate by Jackson and Laine. Relative to that work we include the electron mass in our computations, but restrict our analysis to the enhanced $t$-channel contributions. The fractional change in $N_{\mathrm{eff}}^{\mathrm{SM}}$ due to the rate correction is of order $10^{-5}$ or below, i.e., about a factor of 30 smaller than that recently claimed by Cielo {\it et al.}, and below the nominal computational uncertainties of the current benchmark value of $N_{\mathrm{eff}}^{\mathrm{SM}}=3.0440\pm 0.0002$. We therefore conclude that aforementioned number remains to be the state-of-the-art benchmark for $N_{\mathrm{eff}}^{\mathrm{SM}}$ in the standard model of particle physics.

    hep-phastro-ph.COJCAP(2024)·74 citations
11. 11*

    Polarized and unpolarized off-shell $H^{\ast }\to ZZ\to 4\ell$ decay above the $2m_Z$ threshold

    A. I. Hernández-Juárez🇲🇽 · R. Gaitán🇲🇽 · G. Tavares-Velasco🇲🇽

    An analysis of the off-shell $H^{\ast }\to ZZ\to {\overline{\ell }}_1{\ell }_1{\overline{\ell }}_2{\ell }_2$ decay width is presented for both unpolarized and polarized $Z$ gauge bosons in the scenario with the most general $H^{\ast }ZZ$ vertex function, which is given in terms of two $CP$-even (${\hat{b}}_Z$ and ${\hat{c}}_Z$) and one $CP$-odd (${\tilde{b}}_Z$) anomalous couplings. The SM contributions to the $H^{\ast }ZZ$ coupling up to the one-loop level are also included. Explicit analytic results for the unpolarized and polarized $H^{\ast }\to ZZ\to {\overline{\ell }}_1{\ell }_1{\overline{\ell }}_2{\ell }_2$ square amplitudes and the four-body phase space are presented, out of which several observable quantities can be obtained straightforwardly. As far as the numerical analysis is concerned, a cross-check is performed via \texttt{MadGraph5\_aMC@NLO}, where our model was implemented with the aid of FeynRules. We then consider the most stringent bounds on anomalous complex $H^{\ast }ZZ$ couplings and analyze the effects of the polarizations of the $Z$ gauge bosons through the polarized $H^{\ast }\to ZZ\to {\overline{\ell }}_1{\ell }_1{\overline{\ell }}_2{\ell }_2$ decay width as well as left-right and forward-backward asymmetries, which are found to be sensitive to new-physics effects. Particular focus is put on the effects of the absorptive parts of the anomalous $H^{\ast }ZZ$ couplings, which have been largely overlooked up to now in LHC analyses. It is found that the studied observable quantities, particularly the left-right asymmetries, can be helpful to look for effects of $CP$-violation in the $H^{\ast }ZZ$ coupling and set bounds on the absorptive parts. For completeness, we also analyze the case of unpolarized $Z$ gauge bosons.

    hep-phCPC(2024)·8 citations
12. 12*

    Dark matter bound-state formation in the Sun

    Xiaoyong Chu🇦🇹 · Raghuveer Garani🇮🇹 · Camilo García-Cely🇪🇸 · Thomas Hambye🇧🇪

    The Sun may capture asymmetric dark matter (DM), which can subsequently form bound-states through the radiative emission of a sub-GeV scalar. This process enables generation of scalars without requiring DM annihilation. In addition to DM capture on nucleons, the DM-scalar coupling responsible for bound-state formation also induces capture from self-scatterings of ambient DM particles with DM particles already captured, as well as with DM bound-states formed in-situ within the Sun. This scenario is studied in detail by solving Boltzmann equations numerically and analytically. In particular, we take into consideration that the DM self-capture rates require a treatment beyond the conventional Born approximation. We show that, thanks to DM scatterings on bound-states, the number of DM particles captured increases exponentially, leading to enhanced emission of relativistic scalars through bound-state formation, whose final decay products could be observable. We explore phenomenological signatures with the example that the scalar mediator decays to neutrinos. We find that the neutrino flux emitted can be comparable to atmospheric neutrino fluxes within the range of energies below one hundred MeV. Future facilities like Hyper-K, and direct DM detection experiments can further test such scenario.

    hep-phastro-ph.HEJHEP(2024)·9 citations
13. 13*

    Minimal seesaw and leptogenesis with the smallest modular finite group

    Simone Marciano🇮🇹 · Davide Meloni🇮🇹 · Matteo Parriciatu🇮🇹

    We propose a model for leptons based on the smallest modular finite group ${\Gamma }_2\cong S_3$ that, for the first time, accounts for both the hints of large low-energy CP-violation in the lepton sector and the matter-antimatter asymmetry of the Universe, generated by only two heavy right-handed neutrinos. These same states are also employed in a Minimal seesaw mechanism to generate light neutrino masses. Besides the heavy neutrinos, our particle content is the same as the Standard Model (SM), with the addition of one single modulus $\tau$, whose vacuum expectation value is responsible for both the modular and CP-symmetry breakings. We show that this minimalistic SM extension is enough to get an excellent fit to low energy neutrino observables and to the required baryon asymmetry ${\eta }_B$. Predictions for the neutrino mass ordering, effective masses in neutrinoless double beta decay and tritium decay as well as for the Majorana phases are also provided.

    hep-phJHEP(2024)·27 citations
14. 14*

    Dark matter from mediator decay in early matter domination

    Rouzbeh Allahverdi🇺🇸 · Ngo Phuc Duc Loc🇺🇸 · Jacek K. Osiński🇵🇱

    We study dark matter production from mediator decays in scenarios with an epoch of early matter domination. Particles that mediate interactions between dark matter and the standard model particles are kinematically accessible to the thermal bath as long as their mass is below the reheating temperature of the Universe after inflation. Decay of on-shell mediators can then lead to copious production of dark matter during early matter domination or a preceding radiation-dominated phase. In particular, for mediators that are charged under the standard model, it can exceed the standard freeze-in channel due to inverse annihilations at much lower temperatures (often by many orders of magnitude). The requirement to obtain the correct relic abundance severely constrains the parameter space for dark matter masses above a few TeV.

    hep-phastro-ph.COhep-thPRD(2024)·4 citations
15. 15*

    Light quark mediated Higgs boson production in association with a jet at the next-to-next-leading order and beyond

    Tao Liu🇨🇳 · Alexander A. Penin🇨🇦 · Abdur Rehman🇨🇦

    We study the light quark effect on the Higgs boson production in association with a jet at the LHC in the intermediate transverse momentum region between the quark and the Higgs boson mass scales. Though the effect is suppressed by the small Yukawa coupling, it is enhanced by large logarithms of the quark mass ratio to the Higgs boson mass or transverse momentum. Following a remarkable success of the logarithmic expansion [39] for the prediction of the next-to-next-to-leading bottom quark contribution to the total cross section of the Higgs boson production we extend the analysis to its kinematical distributions. A new factorization formula is derived for the light quark mediated $gg\to Hg$ amplitudes and the differential cross section of the process is computed in the logarithmic approximation, which is used for an estimate of the bottom quark effect at the next-to-next-to-leading order.

    hep-phJHEP(2024)·7 citations
16. 16*

    The Path to N${}^3$LO Parton Distributions

    The NNPDF Collaboration: Richard D. Ball🇬🇧 · Andrea Barontini🇮🇹 · Alessandro Candido🇮🇹 · Stefano Carrazza🇮🇹 · Juan Cruz-Martinez🇨🇭 · Luigi Del Debbio🇬🇧 · Stefano Forte🇮🇹 · Tommaso Giani🇳🇱 · Felix Hekhorn🇮🇹 · Zahari Kassabov🇬🇧 · Niccolò Laurenti🇮🇹 · Giacomo Magni🇳🇱 and 6 other authors

    We extend the existing leading (LO), next-to-leading (NLO), and next-to-next-to-leading order (NNLO) NNPDF4.0 sets of parton distribution functions (PDFs) to approximate next-to-next-to-next-to-leading order (aN${}^3$LO). We construct an approximation to the N${}^3$LO splitting functions that includes all available partial information from both fixed-order computations and from small and large $x$ resummation, and estimate the uncertainty on this approximation by varying the set of basis functions used to construct the approximation. We include known N${}^3$LO corrections to deep-inelastic scattering structure functions and extend the FONLL general-mass scheme to $\mathcal{O}\left({\alpha }_s^3\right)$ accuracy. We determine a set of aN${}^3$LO PDFs by accounting both for the uncertainty on splitting functions due to the incomplete knowledge of N${}^3$LO terms, and to the uncertainty related to missing higher corrections (MHOU), estimated by scale variation, through a theory covariance matrix formalism. We assess the perturbative stability of the resulting PDFs, we study the impact of MHOUs on them, and we compare our results to the aN${}^3$LO PDFs from the MSHT group. We examine the phenomenological impact of aN${}^3$LO corrections on parton luminosities at the LHC, and give a first assessment of the impact of aN${}^3$LO PDFs on the Higgs and Drell-Yan total production cross-sections. We find that the aN${}^3$LO NNPDF4.0 PDFs are consistent within uncertainties with their NNLO counterparts, that they improve the description of the global dataset and the perturbative convergence of Higgs and Drell-Yan cross-sections, and that MHOUs on PDFs decrease substantially with the increase of perturbative order.

    hep-phhep-exEPJC(2024)·107 citations
17. 17*

    Casimir Physics beyond the Proximity Force Approximation: The Derivative Expansion

    César D. Fosco🇦🇷 · Fernando C. Lombardo🇦🇷 · Francisco D. Mazzitelli🇦🇷

    We review the derivative expansion (DE) method in Casimir physics, an approach which extends the proximity force approximation (PFA). After introducing and motivating the DE in contexts other than the Casimir effect, we present different examples which correspond to that realm. We focus on different particular geometries, boundary conditions, types of fields, and quantum and thermal fluctuations. Besides providing various examples where the method can be applied, we discuss a concrete example for which the DE cannot be applied; namely, the case of perfect Neumann conditions in 2 + 1 dimensions. By the same example, we show how a more realistic type of boundary condition circumvents the problem. We also comment on the application of the DE to the Casimir-Polder interaction which provides a broader perspective on particle-surface interactions.

    ↳ quant-phcond-mat.otherhep-phhep-thPhysics(2024)·6 citations
18. 18*

    Infrared fixed point in the massless twelve-flavor SU(3) gauge-fermion system

    Curtis Taylor Peterson🇺🇸 · Anna Hasenfratz🇺🇸

    We present strong numerical evidence for the existence of an infrared fixed point in the renormalization group flow of the SU(3) gauge-fermion system with twelve massless fermions in the fundamental representation. Our numerical simulations using nHYP-smeared staggered fermions with Pauli-Villars improvement do not exhibit any first-order bulk phase transition in the investigated parameter region. We utilize an infinite volume renormalization scheme based on the gradient flow transformation to determine the renormalization group $\beta$ function. We identify an infrared fixed point at $g_{\mathrm{GF}\star }^2=6.60(62)$ in the GF scheme and calculate the leading irrelevant critical exponent ${\gamma }_g^{\star }=0.199(32)$. Our prediction for ${\gamma }_g^{\star }$ is consistent with available literature at the $1\text{mbox}-2\sigma$ level.

    ↳ hep-lathep-phhep-thPRD(2024)·18 citations
19. 19*

    Real-time scattering in the lattice Schwinger model

    Irene Papaefstathiou🇩🇪 · Johannes Knolle🇩🇪 · Mari Carmen Bañuls🇩🇪

    Tensor network methods have demonstrated their suitability for the study of equilibrium properties of lattice gauge theories, even close to the continuum limit. We use them in an out-of-equilibrium scenario, much less explored so far, by simulating the real-time collisions of composite mesons in the lattice Schwinger model. Constructing wave-packets of vector mesons at different incoming momenta, we observe the opening of the inelastic channel in which two heavier mesons are produced and identify the momentum threshold. To detect the products of the collision in the strong coupling regime we propose local quantitites that could be measured in current quantum simulation platforms.

    ↳ hep-lathep-phquant-phPRD(2025)·60 citations
20. 20*

    Three-leg form factor on Coulomb branch

    A.V. Belitsky🇺🇸 · L.V. Bork🇷🇺 · J.M. Grumski-Flores🇺🇸 · V.A. Smirnov🇷🇺

    We study the form factor of the lowest component of the stress-tensor multiplet away from the origin of the moduli space in the spontaneously broken, aka Coulomb, phase of the maximally supersymmetric Yang-Mills theory for decay into three massive W-bosons. The calculations are done at two-loop order by deriving and solving canonical differential equations in the asymptotical limit of nearly vanishing W-masses. We confirm our previous findings that infrared physics of `off-shell observables' is governed by the octagon anomalous dimension rather than the cusp. In addition, the form factor in question possesses a nontrivial remainder function, which was found to be identical to the massless case, upon a proper subtraction of infrared logarithms (and finite terms). However, the iterative structure of the object is more intricate and is not simply related to the previous orders in coupling as opposed to amplitudes/form factors at the origin of the moduli space.

    ↳ hep-thhep-phJHEP(2024)·11 citations
21. 21*

    A New Probe of Cosmic Birefringence Using Galaxy Polarization and Shapes

    Weichen Winston Yin🇺🇸 · Liang Dai🇺🇸 · Junwu Huang🇨🇦 · Lingyuan Ji🇺🇸 · Simone Ferraro🇺🇸

    We propose a novel statistical method to measure cosmic birefringence and demonstrate its power in probing parity violation due to axions. Exploiting an empirical correlation between the integrated radio polarization direction of a spiral galaxy and its apparent shape, we devise an unbiased minimum-variance estimator for the rotation angle, which should achieve an uncertainty of $5^{\circ }$--$15^{\circ }$ per galaxy. Large galaxy samples from the forthcoming SKA continuum surveys, together with optical shape catalogs, promise a comparable or even lower noise power spectrum for the rotation angle than in the CMB Stage-IV (CMB-S4) experiment, with different systematics.

    ↳ astro-ph.COastro-ph.GAhep-phPRL(2025)·20 citations
22. 22*

    Analytic solutions for the linearized first-order magnetohydrodynamics and implications for causality and stability

    Zhe Fang🇨🇳 · Koichi Hattori🇨🇳 · Jin Hu🇨🇳

    We address the linear-mode analysis performed near an equilibrium configuration in the fluid rest frame with a dynamical magnetic field perturbed on a constant configuration. We develop a simple and general algorithm for an analytic solution search that works on an order-by-order basis in the derivative expansion. This method can be applied to general sets of hydrodynamic equations. Applying our method to the first-order relativistic magnetohydrodynamics, we demonstrate that the method finds a complete set of solutions. We obtain two sets of analytic solutions for the four and two coupled modes with seven dissipative transport coefficients. The former set has been missing in the literature for a long time due to the difficulties originating from coupled degrees of freedom and strong anisotropy provided by a magnetic field. The newly developed method resolves these difficulties. We also find that the small-momentum expansions of the solutions break down when the momentum direction is nearly perpendicular to an equilibrium magnetic field due to the presence of another small quantity, that is, a trigonometric function representing the anisotropy. We elaborate on the angle dependence of the solutions and provide alternative series representations that work near the right angle. This identifies the origin of a discrepancy found in recent works. Finally, we discuss the issues of causality and stability based on our analytic solutions and recent developments in the literature.

    ↳ physics.plasm-phastro-ph.HEgr-qchep-ph+1PRD(2024)·15 citations
23. 23*

    The Collective Coordinate Fix

    Arindam Bhattacharya🇺🇸 · Jordan Cotler🇺🇸 · Aurélien Dersy🇺🇸 · Matthew D. Schwartz🇺🇸

    Collective coordinates are frequently employed in path integrals to manage divergences caused by fluctuations around saddle points that align with classical symmetries. These coordinates parameterize a manifold of zero modes and more broadly provide judicious coordinates on the space of fields. However, changing from local coordinates around a saddle point to more global collective coordinates is remarkably subtle. The main complication is that the mapping from local coordinates to collective coordinates is generically multi-valued. Consequently one is forced to either restrict the domain of path integral in a delicate way, or otherwise correct for the multi-valuedness by dividing the path integral by certain intersection numbers. We provide a careful treatment of how to fix collective coordinates while accounting for these intersection numbers, and then demonstrate the importance of the fix for free theories. We also provide a detailed study of the fix for interacting theories and show that the contributions of higher intersections to the path integral can be non-perturbatively suppressed. Using a variety of examples ranging from single-particle quantum mechanics to quantum field theory, we explain and resolve various pitfalls in the implementation of collective coordinates.

    ↳ hep-thhep-phquant-phPRD(2024)·18 citations
24. 24*

    An AI-powered Technology Stack for Solving Many-Electron Field Theory

    Pengcheng Hou🇨🇳 · Tao Wang🇺🇸 · Daniel Cerkoney🇺🇸 · Xiansheng Cai🇺🇸 · Zhiyi Li🇨🇳 · Youjin Deng🇨🇳 · Lei Wang🇨🇳 · Kun Chen🇺🇸

    Quantum field theory (QFT) for interacting many-electron systems is fundamental to condensed matter physics, yet achieving accurate solutions confronts computational challenges in managing the combinatorial complexity of Feynman diagrams, implementing systematic renormalization, and evaluating high-dimensional integrals. We present a unifying framework that integrates QFT computational workflows with an AI-powered technology stack. A cornerstone of this framework is representing Feynman diagrams as computational graphs, which structures the inherent mathematical complexity and facilitates the application of optimized algorithms developed for machine learning and high-performance computing. Consequently, automatic differentiation, native to these graph representations, delivers efficient, fully automated, high-order field-theoretic renormalization procedures. This graph-centric approach also enables sophisticated numerical integration; our neural-network-enhanced Monte Carlo method, accelerated via massively parallel GPU implementation, efficiently evaluates challenging high-dimensional diagrammatic integrals. Applying this framework to the uniform electron gas, we determine the quasiparticle effective mass to a precision significantly surpassing current state-of-the-art simulations. Our work demonstrates the transformative potential of integrating AI-driven computational advances with QFT, opening systematic pathways for solving complex quantum many-body problems across disciplines.

    ↳ hep-thcond-mat.str-elcs.LGhep-ph+13 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.