Thu·Jul 6, 2023Thursday·July 6, 2023

1. 01*

   Unveiling the Heavy Neutrino Nature at LHCb

   G. A. Vasquez (1)🇨🇦 · Jilberto Zamora-Saa (2) ((1) University of Victoria, (2) Universidad Andres Bello)🇨🇱

   In this work, we study the lepton number violating Bc meson decays via one intermediate on-shell heavy neutrino. The specific studied process is $B_c^{+}\to {\mu }^{+}N\to {\mu }^{+}{\mu }^{+}{\tau }^{-}\nu$ which could allow distinguishing the nature of the heavy neutrino nature (Dirac or Majorana) by studying the tau lepton energy spectrum in the LHCb experiment. The result suggests that this signature could be observed in the collected data during the HL-LHCb lifetime.

   hep-phPRD(2023)·2 citations
2. 02*

   Femtoscopy of $D$ mesons and light mesons upon unitarized effective field theories

   Juan M. Torres-Rincon🇪🇸 · Àngels Ramos🇪🇸 · Laura Tolos🇪🇸

   Hadron femtoscopy has turned into a powerful tool for accessing space-time information of heavy-ion collisions as well as for studying final-state interactions of hadrons. Recently, heavy-flavor femtoscopy has become feasible using the ALICE detector at the LHC. We compute the correlation function of $D$ mesons and light mesons using an off-shell $T$-matrix approach to access the two-meson wave function, and predict the correlation functions involving charged $D^{+},D^{\ast +},D_s^{+}$ and $D_s^{\ast +}$ with ${\pi }^{\pm }$ and $K^{\pm }$. From the obtained results -- all of them accessible in $p+p$ collision experiments -- we point up the case of $D^{+}{\pi }^{-}$, which is sensitive to the lower state of the two-pole $D_0^{\ast }(2300)$ system. The presence of such poles imprints a depletion on the correlation function, which could potentially be detected in experiments. While preliminary ALICE data do not show evidence of this effect, we suggest to look into the $D_s^{+}{K}^{-}$ system to explore the higher pole of the $D_0^{\ast }(2300)$, as the depletion in the correlation function is more pronounced. Using heavy-quark spin symmetry we also propose exploring the effect of the two poles of the $D_1(2430)$ and predict similar structures in the correlation functions of the $D^{\ast +}{\pi }^{-}$ and $D_s^{\ast +}{K}^{-}$ pairs.

   hep-phnucl-thPRD(2023)·50 citations
3. 03*

   A renormalization group improvement for thermally resummed effective potential

   Koichi Funakubo🇯🇵 · Eibun Senaha

   We propose a novel method for renormalization group improvement of thermally resummed effective potential. In our method, $\beta$-functions are temperature dependent as a consequence of the divergence structure in resummed perturbation theory. In contrast to the ordinary $\overline{\text{MS}}$ scheme, the renormalization group invariance of the resummed finite-temperature effective potential holds order by order, which significantly mitigates a notorious renormalization scale dependence of phase transition quantities such as a critical temperature even at the one-loop order. We also devise a tractable method that enables one to incorporate temperature-dependent higher-order corrections by fully exploiting the renormalization group invariance.

   hep-phPRD(2024)·6 citations
4. 04*

   X17 discovery potential from $\gamma D\to e^{+}{e}^{-}pn$ with neutron tagging

   Cornelis J.G. Mommers🇩🇪 · Marc Vanderhaeghen🇩🇪

   We propose a novel direct search experiment for X17 using the reaction $\gamma D\to e^{+}{e}^{-}pn$. X17 is a hypothetical particle conjectured by the ATOMKI collaboration to explain anomalous signals around 17 MeV in excited ${}^8$Be, ${}^4$He and ${}^{12}$C nuclear decays via internal pair creation. It has been subject to a global experimental and theoretical research program. The proposed direct search in $\gamma D\to e^{+}{e}^{-}pn$ can verify the existence of X17 through the production on a quasi-free neutron, and determine its quantum numbers separate from ongoing and planned nuclear-decay experiments. This is especially timely in view of the theoretical tension between results from the ${}^{12}$C and ${}^8$Be measurements. Using the plane-wave impulse approximation, we quantify the expected signal and background for pseudoscalar, vector and axial-vector X17 scenarios. We optimize the kinematics for the quasi-free neutron region with the upcoming MAGIX experiment at MESA in mind and show that for all three scenarios the X17 signal is clearly visible above the QED background.

   hep-phnucl-exnucl-th2 citations
5. 05*

   Phase transitions, anomalous baryon number violation and electroweak multiplet dark matter

   Yanda Wu🇨🇳 · Wenxing Zhang🇨🇳 · Michael J. Ramsey-Musolf🇨🇳

   We perform a comprehensive analysis of baryon number violation during an electroweak phase transition (EWPT) within the framework of a scalar electroweak multiplet extension of the Standard Model. We classify the multiplet representations, topological properties, and corresponding thermal histories. Sphaleron or monopole topological field solutions emerge during the EWPT depending on the stage of the phase transition and the hypercharge of the new scalar multiplet. Furthermore, the monopole field solution pertains when the neutral component of the additional scalar multiplet is a viable dark matter candidate. We further analyze other formal considerations, including the construction of the \lq\lq sphaleron matrix\rq\rq\, for higher dimensional representations, computation of the sphaleron and monopole masses, and the choice of boundary conditions when solving the field equations of motion. We apply these considerations to the computation of sphaleron energy and monopole mass within the context of a multi-step EWPT, employing the SU(2)${}_L$ septuplet scalar extension to the Standard Model (SM) as a case of study from the minimal dark matter paradigm. For the first step of a two-step EWPT, we delineate the relationship between the monopole mass and the parameters relevant to dark matter phenomenology.

   hep-phPRD(2025)·5 citations
6. 06*

   Spin-1 Thermal Targets for Dark Matter Searches at Beam Dump and Fixed Target Experiments

   Riccardo Catena🇸🇪 · Taylor R. Gray🇸🇪

   The current framework for dark matter searches at beam dump and fixed target experiments relies on four benchmark models, the complex scalar, inelastic scalar, pseudo-Dirac and finally, Majorana DM models. While this approach has so far been successful in the interpretation of the available data, it a priori excludes the possibility that DM is made of spin-1 particles -- a restriction which is neither theoretically nor experimentally justified. In this work we extend the current landscape of sub-GeV DM models to a set of models for spin-1 DM, including a family of simplified models (involving one DM candidate and one mediator -- the dark photon) and an ultraviolet complete model based on a non-abelian gauge group where DM is a spin-1 Strongly Interacting Massive Particle. For each of these models, we calculate the DM relic density, the expected number of signal events at beam dump experiments, the rate of energy injection in the early universe thermal bath and in the Intergalactic Medium, as well as the helicity amplitudes for forward processes subject to the unitary bound. We then compare these predictions with experimental results from Planck, CMB surveys, IGM temperature observations, LSND, MiniBooNE, NA64, and BaBar and with available projections from LDMX and Belle II. Through this comparison, we identify the regions in the parameter space of the models considered in this work where DM is simultaneously thermally produced, compatible with present observations, and within reach at Belle II and LDMX. We find that the simplified models are strongly constrained by current beam dump experiments and the unitarity bound, and will thus be conclusively probed in the first stage of LDMX data taking. We also find that the SIMP model explored in this work predicts the observed DM abundance, is compatible with current observations and within reach at LDMX in a wide region of the parameter space.

   hep-phastro-ph.COJCAP(2023)·16 citations
7. 07*

   Resummation of Next-to-Leading Non-Global Logarithms at the LHC

   Thomas Becher🇨🇭 · Nicolas Schalch🇨🇭 · Xiaofeng Xu🇩🇪

   In cross sections with angular cuts, an intricate pattern of enhanced higher-order corrections known as non-global logarithms arises. The leading logarithmic terms were computed numerically two decades ago, but the resummation of subleading non-global logarithms remained a challenge that we solve in this Letter using renormalization group methods in effective field theory. To achieve next-to-leading logarithmic accuracy, we implement the two-loop anomalous dimension governing the resummation of non-global logarithms into a large-$N_c$ parton shower framework, together with one-loop matching corrections. As a first application, we study the interjet energy flow in $e^{+}{e}^{-}$ annihilation into two jets. We then present, for the first time, resummed predictions at next-to-leading logarithmic accuracy for a gap-between-jets observable at hadron colliders.

   hep-phPRL(2024)·43 citations
8. 08*

   Subleading Effects in Soft-Gluon Emission at One-Loop in Massless QCD

   Michał Czakon🇩🇪 · Felix Eschment🇩🇪 · Tom Schellenberger🇩🇪

   We elucidate the structure of the next-to-leading-power soft-gluon expansion of arbitrary one-loop massless-QCD amplitudes. The expansion is given in terms of universal colour-, spin- and flavour-dependent operators acting on process-dependent gauge-invariant amplitudes. The result is proven using the method of expansion-by-regions and tested numerically on non-trivial processes with up to six partons. In principle, collinear-region contributions are expressed in terms of convolutions of universal jet operators and process-dependent amplitudes with two collinear partons. However, we evaluate these convolutions exactly for arbitrary processes. This is achieved by deriving an expression for the next-to-leading power expansion of tree-level amplitudes in the double-collinear limit, which is a novel result as well. Compared to previous studies, our analysis, besides being more general, yields simpler formulae that avoid derivatives of process-dependent amplitudes in the collinear limit.

   hep-phhep-thJHEP(2023)·14 citations
9. 09*

   $D_s\to f_0$ form factors and the $D_s^{+}\to {\left[\pi \pi \right]}_{\mathrm{S}}{e}^{+}{\nu }_e$ decay from light-cone sum rules

   Shan Cheng🇨🇳 · Shu-Lei Zhang🇨🇳

   In this paper we revisit $D_s\to f_0$ form factors from the light-cone sum rules with the light meson light-cone distribution amplitudes. The main motivation of this study is the differential decay width of $D_s\to {\left[\pi \pi \right]}_{\mathrm{S}}e{\nu }_e$ measured recently by BESIII collaboration and the $D_s\to f_0$ form factor extracted under the intermediate resonant model. Our result of the differential width of $D_s^{+}\to f_0(\to {\left[\pi \pi \right]}_{\mathrm{S}})e^{+}{\nu }_e$ decay obtained under the narrow width approximation is a litter bit lower than the data, the result obtained under the resonant Flatté model is in consistent with the data while shows a litter bit larger, indicating a sizable mixing $\sim 20°$ between $\bar{s}s$ and $\bar{u}u+\bar{d}d$ of $f_0$. In order to obtain a model independent prediction, we suggest to calculate $D_s\to {\left[\pi \pi \right]}_{\mathrm{S}}$ form factors with the isoscalar scalar dipion light-cone distribution amplitudes. Our calculation of $D_s\to {\left[\pi \pi \right]}_{\mathrm{S}}$ form factors is carried out at the leading twist level due to the finite knowledge of dipion system, the result of differential width shows a moderate evolution in contrast to that obtained from the narrow width approximation and the Flatté model, revealing a bright prospect to study the four-body leptonic decays of heavy mesons with the dimeson light-cone distribution amplitudes.

   hep-phhep-exEPJC(2024)·9 citations
10. 10*

    Transverse $\Lambda$ polarization in $e^{+}{e}^{-}$ annihilations and in SIDIS processes at the EIC within TMD factorization

    Umberto D'Alesio🇮🇹 · Leonard Gamberg🇺🇸 · Francesco Murgia🇮🇹 · Marco Zaccheddu🇮🇹

    We present a phenomenological study on the role of charm contribution and $SU(2)$ isospin symmetry in the extraction of the $\Lambda$ polarizing fragmentation functions from $e^{+}{e}^{-}\to {\Lambda }^{\uparrow }({\bar{\Lambda }}^{\uparrow })h+X$ annihilation processes. We adopt the well-established transverse-momentum-dependent factorization formalism, within the Collins-Soper-Sterman evolution scheme at next-to-leading logarithm accuracy, carefully exploiting the role of the nonperturbative component of the polarizing fragmentation function. We then discuss the impact of these results on the predictions for transverse $\Lambda$, $\bar{\Lambda }$ polarization in semi-inclusive deep inelastic scattering processes at typical energies of the future Electron-Ion Collider.

    hep-phPRD(2023)·11 citations
11. 11*

    Constraints on Neutrino Self-Interactions from IceCube Observation of NGC 1068

    Jeffrey M. Hyde🇺🇸

    The active galaxy NGC 1068 was recently identified by the IceCube neutrino observatory as the first known steady-state, extragalactic neutrino point source, associated with about 79 events over ten years. We use the IceCube data to place limits on possible neutrino self-interactions mediated by scalar particles with mass between 1 - 10 MeV. We find that constraints on flavor-specific ${\nu }_{\tau }$ self-interactions with low mediator masses are comparable to constraints derived from the diffuse high-energy neutrino flux at low energies, while constraints on flavor-universal self-interactions are less restrictive than current bounds.

    hep-phastro-ph.HE6 citations
12. 12*

    Evolution of compact states to molecular ones with coupled channels: The case of the $X(3872)$

    Jing Song🇨🇳 · L.R.Dai🇨🇳 · E.Oset🇪🇸

    We study the molecular probability of the $X(3872)$ in the $D^0{\bar{D}}^{\ast 0}$ and $D^{+}{D}^{\ast -}$ channels in several scenarios. One of them assumes that the state is purely due to a genuine nonmolecular component. However, it gets unavoidably dressed by the meson components to the point that in the limit of zero binding of the $D^0{\bar{D}}^{\ast 0}$ component becomes purely molecular. Yet, the small but finite binding allows for a nonmolecular state when the bare mass of the genuine state approaches the $D^0{\bar{D}}^{\ast 0}$ threshold, but, in this case the system develops a small scattering length and a huge effective range for this channel in flagrant disagreement with present values of these magnitudes. Next we discuss the possibility to have hybrid states stemming from the combined effect of a genuine state and a reasonable direct interaction between the meson components, where we find cases in which the scattering length and effective range are still compatible with data, but even then the molecular probability is as big as $95\%$. Finally, we perform the calculations when the binding stems purely from the direct interaction between the meson-meson components. In summary we conclude, that while present data definitely rule out the possibility of a dominant nonmolecular component, the precise value of the molecular probability requires a more precise determination of the scattering length and effective range of the $D^0{\bar{D}}^{\ast 0}$ channel, as well as the measurement of these magnitudes for the $D^{+}{D}^{\ast -}$ channel which have not been determined experimentally so far.

    hep-phPRD(2023)·39 citations
13. 13*

    ${\nu }^2$-Flows: Fast and improved neutrino reconstruction in multi-neutrino final states with conditional normalizing flows

    John Andrew Raine🇨🇭 · Matthew Leigh🇨🇭 · Knut Zoch🇨🇭 · Tobias Golling🇨🇭

    In this work we introduce ${\nu }^2$-Flows, an extension of the $\nu$-Flows method to final states containing multiple neutrinos. The architecture can natively scale for all combinations of object types and multiplicities in the final state for any desired neutrino multiplicities. In $t\bar{t}$ dilepton events, the momenta of both neutrinos and correlations between them are reconstructed more accurately than when using the most popular standard analytical techniques, and solutions are found for all events. Inference time is significantly faster than competing methods, and can be reduced further by evaluating in parallel on graphics processing units. We apply ${\nu }^2$-Flows to $t\bar{t}$ dilepton events and show that the per-bin uncertainties in unfolded distributions is much closer to the limit of performance set by perfect neutrino reconstruction than standard techniques. For the chosen double differential observables ${\nu }^2$-Flows results in improved statistical precision for each bin by a factor of 1.5 to 2 in comparison to the Neutrino Weighting method and up to a factor of four in comparison to the Ellipse approach.

    hep-phcs.LGhep-exPRD(2024)·30 citations
14. 14*

    On the two-loop BSM corrections to $h⟶\gamma \gamma$ in the aligned THDM

    Giuseppe Degrassi🇮🇹 · Pietro Slavich🇫🇷

    We compute the two-loop BSM contributions to the $h⟶\gamma \gamma$ decay width in the aligned THDM. We adopt the simplifying assumptions of vanishing EW gauge couplings and vanishing mass of the SM-like Higgs boson, which allow us to exploit a low-energy theorem connecting the $h\gamma \gamma$ amplitude to the derivative of the photon self-energy w.r.t. the Higgs field. We briefly discuss the numerical impact of the newly-computed contributions, showing that they may be required for a precise determination of $\Gamma [h\to \gamma \gamma ]$ in scenarios where the quartic Higgs couplings are large.

    hep-phEPJC(2023)·17 citations
15. 15*

    Probing factorization violation with vector angularities

    Pim Bijl🇳🇱 · Steven Niedenzu🇳🇱 · Wouter J. Waalewijn🇳🇱

    Factorization underlies all predictions at the Large Hadron Collider, but has only been rigorously proven in a few cases. One of these cases is the Drell-Yan process, $pp\to Z/\gamma +X$, in the limit of small boson transverse momentum. We introduce a one-parameter family of observables, that we call vector angularities, of which the transverse momentum is a special case. This enables the study of factorization violation, with a smooth transition to the limit for which factorization has been established. Like the angularity event shapes, vector angularities are a sum of transverse momenta weighted by rapidity, but crucially this is a vector sum rather than a sum of the magnitude of transverse momenta. We study these observables in Pythia, using the effect of multi-parton interactions (MPI) as a proxy factorization violation, finding a negligible effect in the case where factorization is established but sizable effects away from it. We also present a factorization formula for the cross section, that does not include factorization violating contributions from Glauber gluons, and thus offers a baseline for studying factorization violation experimentally using vector angularities. Our predictions at next-to-leading logarithmic accuracy (NLL${}^{\prime }$) are in good in agreement with Pythia (not including MPI), and can be extended to higher order.

    hep-phnucl-thPRD(2024)·4 citations
16. 16*

    A phenomenological estimate of isospin breaking in hadronic vacuum polarization

    Martin Hoferichter🇨🇭 · Gilberto Colangelo🇨🇭 · Bai-Long Hoid🇨🇭 · Bastian Kubis🇩🇪 · Jacobo Ruiz de Elvira🇪🇸 · Dominic Schuh🇩🇪 · Dominik Stamen🇩🇪 · Peter Stoffer🇨🇭

    Puzzles in the determination of the hadronic-vacuum-polarization contribution currently impede a conclusive interpretation of the precision measurement of the anomalous magnetic moment of the muon at the Fermilab experiment. One such puzzle concerns tensions between evaluations in lattice QCD and using $e^{+}{e}^{-}\to \text{hadrons}$ cross-section data. In lattice QCD, the dominant isospin-symmetric part and isospin-breaking (IB) corrections are calculated separately, with very different systematic effects. Identifying these two pieces in a data-driven approach provides an opportunity to compare them individually and trace back the source of the discrepancy. Here, we estimate the IB component of the lattice-QCD calculations from phenomenology, based on a comprehensive study of exclusive contributions that can be enhanced via infrared singularities, threshold effects, or hadronic resonances, including, for the first time, in the $e^{+}{e}^{-}\to 3\pi$ channel. We observe sizable cancellations among different channels, with a sum that even suggests a slightly larger result for the QED correction than obtained in lattice QCD. We conclude that the tensions between lattice QCD and $e^{+}{e}^{-}$ data therefore cannot be explained by the IB contributions in the lattice-QCD calculations.

    hep-phhep-exhep-latnucl-thPRL(2023)·56 citations
17. 17*

    Correlations of $C$ and $CP$ violation in $\eta \to {\pi }^0{\ell }^{+}{\ell }^{-}$ and ${\eta }^{\prime }\to \eta {\ell }^{+}{\ell }^{-}$

    Hakan Akdag🇩🇪 · Bastian Kubis🇩🇪 · Andreas Wirzba🇩🇪

    Based on recent progress in the systematic analysis of $C$ and $CP$ violation in the light-meson sector, we calculate the $C$-odd transition amplitudes $\eta \to {\pi }^0{\ell }^{+}{\ell }^{-}$ and ${\eta }^{\prime }\to \eta {\ell }^{+}{\ell }^{-}$. Focusing on long-distance contributions driven by the lowest-lying hadronic intermediate states, we work out the correlations between these beyond-the-Standard-Model signals and the Dalitz-plot asymmetries in $\eta \to {\pi }^0{\pi }^{+}{\pi }^{-}$ and ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$, using dispersion theory.

    hep-phhep-exnucl-thJHEP(2024)·10 citations
18. 18*

    Falsifying Pati-Salam models with LIGO

    Peter Athron🇨🇳 · Csaba Balázs🇦🇺 · Tomás E. Gonzalo🇩🇪 · Matthew Pearce🇦🇺

    We demonstrate that existing gravitational wave data from LIGO already places constraints on well motivated Pati-Salam models that allow the Standard Model to be embedded within grand unified theories. For the first time in these models we also constrain the parameter space by requiring that the phase transition completes, with the resulting constraint being competitive with the limits from LIGO data. Both constraints are complementary to the LHC constraints and can exclude scenarios that are much heavier than can be probed in colliders. Finally we show that results from future LIGO runs, and the planned Einstein telescope, will substantially increase the limits we place on the parameter space.

    hep-phastro-ph.COPRD(2024)·11 citations
19. 19*

    Isospin-breaking effects in the three-pion contribution to hadronic vacuum polarization

    Martin Hoferichter🇨🇭 · Bai-Long Hoid🇨🇭 · Bastian Kubis🇩🇪 · Dominic Schuh🇩🇪

    Isospin-breaking (IB) effects are required for an evaluation of hadronic vacuum polarization at subpercent precision. While the dominant contributions arise from the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ channel, also IB in the subleading channels can become relevant for a detailed understanding, e.g., of the comparison to lattice QCD. Here, we provide such an analysis for $e^{+}{e}^{-}\to 3\pi$ by extending our dispersive description of the process, including estimates of final-state radiation (FSR) and $\rho$-$\omega$ mixing. In particular, we develop a formalism to capture the leading infrared-enhanced effects in terms of a correction factor ${\eta }_{3\pi }$ that generalizes the analog treatment of virtual and final-state photons in the $2\pi$ case. The global fit to the $e^{+}{e}^{-}\to 3\pi$ data base, subject to constraints from analyticity, unitarity, and the chiral anomaly, gives $a_{\mu }^{3\pi }{|}_{\le 1.8\text{GeV}}=45.91(53)\times 10^{-10}$ for the total $3\pi$ contribution to the anomalous magnetic moment of the muon, of which $a_{\mu }^{\text{FSR}}[3\pi ]=0.51(1)\times 10^{-10}$ and $a_{\mu }^{\rho \text{-}\omega }[3\pi ]=-2.68(70)\times 10^{-10}$ can be ascribed to IB. We argue that the resulting cancellation with $\rho$-$\omega$ mixing in $e^{+}{e}^{-}\to 2\pi$ can be understood from a narrow-resonance picture, and provide updated values for the vacuum-polarization-subtracted vector-meson parameters $M_{\omega }=782.70(3)\text{MeV}$, $M_{\varphi }=1019.21(2)\text{MeV}$, ${\Gamma }_{\omega }=8.71(3)\text{MeV}$, and ${\Gamma }_{\varphi }=4.27(1)\text{MeV}$.

    hep-phhep-exhep-latnucl-thJHEP(2023)·52 citations
20. 20*

    TASI 2022 lectures on LHC experiments

    Heather M. Gray🇺🇸

    The field of experimental particle physics studies the fundamental particles and forces that constitute matter and radiation. Frequently the experimental tools used to enable this study are accelerators and detectors. The Large Hadron Collider (LHC) is the highest energy proton-proton accelerator currently operating and where the ATLAS and CMS collaboration discovered and are currently studying the properties of the Higgs boson. These notes provide a short introduction to accelerators and detectors using the LHC and its detectors as examples. The detector section will focus on two types of detectors extensively used today: tracking detectors and calorimeters. The notes will then discuss the algorithms used to process the information from the detectors and how that information is used for physics analysis using the search for the decay of the Higgs boson to bottom quarks.

    ↳ hep-exhep-ph1 citation
21. 21*

    Kinetic theory for spin-polarized relativistic plasmas

    Daniel Seipt🇩🇪 · Alec G. R. Thomas🇺🇸

    The investigation of spin and polarization effects in ultra-high intensity laser-plasma and laser-beam interactions has become an emergent topic in high-field science recently. In this paper we derive a relativistic kinetic description of spin-polarized plasmas, where QED effects are taken into account via Boltzmann-type collision operators under the local constant field approximation. The emergence of anomalous precession is derived from one-loop self-energy contributions in a strong background field. We are interested, in particular, in the interplay between radiation reaction effects and the spin polarization of the radiating particles. For this we derive equations for spin-polarized quantum radiation reaction from moments of the spin-polarized kinetic equations. By comparing with the classical theory, we identify and discuss the spin-dependent radiation reaction terms, and radiative contributions to spin dynamics.

    ↳ physics.plasm-phhep-phPhys.Plasmas(2023)·13 citations
22. 22*

    Axion-Gauge Dynamics During Inflation as the Origin of Pulsar Timing Array Signals and Primordial Black Holes

    Caner Unal🇮🇱 · Alexandros Papageorgiou🇰🇷 · Ippei Obata🇯🇵

    We demonstrate that the recently announced signal for a stochastic gravitational wave background (SGWB) from pulsar timing array (PTA) observations, if attributed to new physics, is compatible with primordial GW production due to axion-gauge dynamics during inflation. More specifically we find that axion-$U(1)$ models may lead to sufficient particle production to explain the signal while simultaneously source some fraction of sub-solar mass primordial black holes (PBHs) as a signature. Moreover there is a parity violation in GW sector, hence the model suggests chiral GW search as a concrete target for future. We further analyze the axion-$SU(2)$ coupling signatures and find that in the low/mild backreaction regime, it is incapable of producing PTA evidence and the tensor-to-scalar ratio is low at the peak, hence it overproduces scalar perturbations and PBHs.

    ↳ astro-ph.COgr-qchep-phPLB(2024)·79 citations
23. 23*

    Cosmological Background Interpretation of Pulsar Timing Array Data

    Daniel G. Figueroa🇪🇸 · Mauro Pieroni🇨🇭 · Angelo Ricciardone🇮🇹 · Peera Simakachorn🇪🇸

    We discuss the interpretation of the detected signal by Pulsar Timing Array (PTA) observations as a gravitational wave background (GWB) of cosmological origin. We combine NANOGrav 15-years and EPTA-DR2new data sets and confront them against backgrounds from supermassive black hole binaries (SMBHBs), and cosmological signals from inflation, cosmic (super)strings, first-order phase transitions, Gaussian and non-Gaussian large scalar fluctuations, and audible axions. We find that scalar-induced, and to a lesser extent audible axion and cosmic superstring signals, provide a better fit than SMBHBs. These results depend, however, on modeling assumptions, so further data and analysis are needed to reach robust conclusions. Independently of the signal origin, the data strongly constrain the parameter space of cosmological signals, for example, setting an upper bound on primordial non-Gaussianity at PTA scales as $|f_{nl}|\lesssim 2.34$ at 95% CL.

    ↳ astro-ph.COgr-qchep-phPRL(2024)·210 citations
24. 24*

    Search for Light Dark Matter with NA64 at CERN

    Yu. M. Andreev · D. Banerjee · B. Banto Oberhauser · J. Bernhard · P. Bisio · A. Celentano · N. Charitonidis · A. G. Chumakov · D. Cooke · P. Crivelli · E. Depero · A. V. Dermenev and 51 other authors

    Thermal dark matter models with particle $\chi$ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV $\chi$ production through the interaction mediated by a new vector boson, called the dark photon $A^{\prime }$, in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS. With $9.37\times 10^{11}$ electrons on target collected during 2016-2022 runs NA64 probes for the first time the well-motivated region of parameter space of benchmark thermal scalar and fermionic dark matter models. No evidence for dark matter production has been found. This allows us to set the most sensitive limits on the $A^{\prime }$ couplings to photons for masses $m_{A^{\prime }}\lesssim 0.35$ GeV, and to exclude scalar and Majorana dark matter with the $\chi -A^{\prime }$ coupling ${\alpha }_D\le 0.1$ for masses $0.001\lesssim m_{\chi }\lesssim 0.1$ GeV and $3m_{\chi }\le m_{A^{\prime }}$.

    ↳ hep-exhep-phPRL(2023)·135 citations
25. 25*

    High-Energy Collision of Quarks and Mesons in the Schwinger Model: From Tensor Networks to Circuit QED

    Ron Belyansky🇺🇸 · Seth Whitsitt🇺🇸 · Niklas Mueller🇺🇸 · Ali Fahimniya🇺🇸 · Elizabeth R. Bennewitz🇺🇸 · Zohreh Davoudi🇺🇸 · Alexey V. Gorshkov🇺🇸

    With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in 1+1 dimensions. Working in the bosonized formulation of the model and in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multi-particle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. Furthermore, we propose an analog circuit-QED implementation of the scattering process that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. This study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.

    ↳ quant-phcond-mat.mes-hallhep-lathep-ph+1PRL(2024)·97 citations
26. 26*

    Searches for dark matter decay with ultra-high-energy neutrinos endure backgrounds

    Damiano F. G. Fiorillo🇩🇰 · Victor Valera🇩🇰 · Mauricio Bustamante🇩🇰 · Walter Winter🇩🇪

    Next-generation ultra-high-energy (UHE) neutrino telescopes, presently under planning, will have the potential to probe the decay of heavy dark matter (DM) into UHE neutrinos, with energies in excess of $10^7$~GeV. Yet, this potential may be deteriorated by the presence of an unknown background of UHE neutrinos, cosmogenic or from astrophysical sources, not of DM origin and seemingly large enough to obscure the DM signature. We show that leveraging the angular and energy distributions of detected events safeguards future searches for DM decay against such backgrounds. We focus on the radio-detection of UHE neutrinos in the planned IceCube-Gen2 neutrino telescope, which we model in state-of-the-art detail. We report promising prospects for the discovery potential of DM decay into UHE neutrinos, the measurement of DM mass and lifetime, and limits on the DM lifetime, despite the presence of a large background, without prior knowledge of its size and shape.

    ↳ astro-ph.HEhep-phPRD(2023)·23 citations
27. 27*

    Evolution of entanglement entropy at SU($N$) deconfined quantum critical points

    Menghan Song🇨🇳 · Jiarui Zhao🇨🇳 · Meng Cheng🇺🇸 · Cenke Xu🇺🇸 · Michael M. Scherer🇩🇪 · Lukas Janssen🇩🇪 · Zi Yang Meng🇨🇳

    Over the past two decades, the enigma of the deconfined quantum critical point (DQCP) has attracted broad attention across the condensed matter, quantum field theory, and high-energy physics communities, as it is expected to offer a new paradigm in theory, experiment, and numerical simulations that goes beyond the Landau-Ginzburg-Wilson framework of symmetry breaking and phase transitions. However, the nature of DQCP has been controversial. For instance, in the square-lattice spin-1/2 $J$-$Q$ model, believed to realize the DQCP between Néel and valence bond solid states, conflicting results, such as first-order versus continuous transition, and critical exponents incompatible with conformal bootstrap bounds, have been reported. The enigma of DQCP is exemplified in its anomalous logarithmic subleading contribution in its entanglement entropy (EE), which was discussed in recent studies. In the current work, we demonstrate that similar anomalous logarithmic behavior persists in a class of models analogous to the DQCP. We systematically study the quantum EE of square-lattice SU($N$) DQCP spin models. Based on large-scale quantum Monte Carlo computation of the EE, we show that for a series of $N$ smaller than a critical value, the anomalous logarithmic behavior always exists in the EE, which implies that the previously determined DQCPs in these models do not belong to conformal fixed points. In contrast, when $N\ge N_c$ with a finite $N_c$ that we evaluate to lie between $7$ and $8$, the DQCPs are consistent with conformal fixed points that can be understood within the Abelian Higgs field theory with $N$ complex components.

    ↳ cond-mat.str-elhep-lathep-phhep-thSci.Adv.(2025)·64 citations
28. 28*

    Piercing of a solitonic boson star by a black hole

    Zhen Zhong🇵🇹 · Vitor Cardoso🇩🇰 · Taishi Ikeda🇮🇹 · Miguel Zilhão🇵🇹

    Recently, the piercing of a mini boson star by a black hole was studied, with tidal capture and the discovery of a "gravitational atom" being reported ( arXiv:2206.00021 [gr-qc] ). Building on this research, we extend the study by including a hexic solitonic potential and explore the piercing of a solitonic boson star by a black hole. Notably, the solitonic boson star can reach higher compactness, which one might expect could alter the dynamics in this context. Our findings suggest that even when the black hole's size approaches the test particle limit, the solitonic boson star is easily captured by the black hole due to an extreme tidal capture process. Regardless of the black hole initial mass and velocity, our results indicate that over 85% of the boson star material is accreted. Thus, the self-interaction does not alter the qualitative behavior of the system.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2023)·15 citations
29. 29*

    Analog vacuum decay from vacuum initial conditions

    Alexander C. Jenkins🇬🇧 · Jonathan Braden🇨🇦 · Hiranya V. Peiris🇬🇧 · Andrew Pontzen🇬🇧 · Matthew C. Johnson🇨🇦 · Silke Weinfurtner🇬🇧

    Ultracold atomic gases can undergo phase transitions that mimic relativistic vacuum decay, allowing us to empirically test early-Universe physics in tabletop experiments. We investigate the physics of these analog systems, going beyond previous analyses of the classical equations of motion to study quantum fluctuations in the cold-atom false vacuum. We show that the fluctuation spectrum of this vacuum state agrees with the usual relativistic result in the regime where the classical analogy holds, providing further evidence for the suitability of these systems for studying vacuum decay. Using a suite of semiclassical lattice simulations, we simulate bubble nucleation from this analog vacuum state in a 1D homonuclear potassium-41 mixture, finding qualitative agreement with instanton predictions. We identify realistic parameters for this system that will allow us to study vacuum decay with current experimental capabilities, including a prescription for efficiently scanning over decay rates, and show that this setup will probe the quantum (rather than thermal) decay regime at temperatures $T\lesssim 10\mathrm{nK}$. Our results help lay the groundwork for using upcoming cold-atom experiments as a new probe of nonperturbative early-Universe physics.

    ↳ cond-mat.quant-gasastro-ph.COgr-qchep-ph+1PRD(2024)·33 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.