Thu·Jun 13, 2024Thursday·June 13, 2024

1. 01*

   Lighting up the Photon Wigner Distribution via Dilepton Productions

   Yu Shi🇨🇳 · Lin Chen🇪🇸 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳

   We present a systematic investigation of lepton pair production through photon-photon fusion processes in heavy-ion collisions. It is demonstrated that the dilepton production at a given impact parameter ($b_{\perp }$) with a fixed transverse momentum imbalance ($q_{\perp }$) can be factorized into a unified formula in terms of the Wigner photon distribution of heavy nuclei. We show that this framework provides a comprehensive description of all the relevant data from RHIC to the LHC, with a strong evidence that the quasi-real photon can be radiated not only from the nucleus as a whole, standing for the coherent contribution, but also from the sub-structures inside the nucleus, representing the incoherent contribution. Further predictions are made for the anisotropies in the correlations between $q_{\perp }$, $b_{\perp }$, and the dilepton transverse momentum ($P_{\perp }$). This will help us to constrain the photon Wigner distribution which plays a crucial role to study the gluonic matter of nucleus at small-$x$ through the diffractive photoproduction processes in heavy ion collision.

   hep-phhep-exnucl-exnucl-thPLB(2025)·13 citations
2. 02*

   A 17 MeV pseudoscalar and the LSND, MiniBooNE and ATOMKI anomalies

   Waleed Abdallah🇪🇬 · Raj Gandhi🇮🇳 · Tathagata Ghosh🇮🇳 · Najimuddin Khan🇮🇳 · Samiran Roy🇮🇳 · Subhojit Roy🇺🇸

   In the absence of any new physics signals at the Large Hadron Collider (LHC), anomalous results at low energy experiments have become the subject of increased attention. We focus on three such results from the LSND, MiniBooNE (MB), and ATOMKI experiments. A 17 MeV pseudoscalar mediator ($a^{\prime }$) can account for two (${}^8$Be and ${}^4$He) out of the three cases in which excess events have been seen in pair creation transitions in ATOMKI. We incorporate this mediator in a gauge invariant extension of the Standard Model (SM) with a second Higgs doublet and three singlet (seesaw) neutrinos ($N_i,i=1,2,3$). $N_{1,2}$ participate in an interaction in MB and LSND which, with $a^{\prime }$ as mediator, leads to the production of $e^{+}{e}^{-}$ pairs. The $N_i$ also lead to mass-squared differences for SM neutrinos in agreement with global oscillation data. We first show that such a model offers a natural joint solution to the MB and LSND excesses, providing excellent fits to their data. Next, using the values of the couplings to the quarks and electrons which are required to explain pair creation nuclear transition data for ${}^8$Be and ${}^4$He in ATOMKI, we show that these values still lead to fits for MB and LSND data. However, once ATOMKI is incorporated, we find that strong constraints from the decays $K^{+}\to {\pi }^{+}{a}^{\prime }(a^{\prime }\to e^{+}{e}^{-})$ and ${\pi }^{+}\to$ $e^{+}{\nu }_e{e}^{+}{e}^{-}$ come into play. While our solution is in conformity with the bounds on the former decay, it remains in tension with $90\%$ CL bounds on the latter. We also discuss other constraints from both collider and non-collider experiments and from electroweak precision data, stability and unitarity. We compute the contributions to the electron and muon $g-2$ up to two loops for our model. We discuss tests of the model in upcoming experiments.

   hep-phhep-exJHEP(2024)·10 citations
3. 03*

   Algorithms for numerically stable scattering amplitudes

   Enrico Bothmann🇩🇪 · John M. Campbell🇺🇸 · Stefan Höche🇺🇸 · Max Knobbe🇩🇪

   The numerically stable evaluation of scattering matrix elements near the infrared limit of gauge theories is of great importance for the success of collider physics experiments. We present a novel algorithm that utilizes double precision arithmetic and reaches higher precision than a naive quadruple precision implementation at smaller computational cost. The method is based on physics-driven modifications to propagators, vertices and external polarizations.

   hep-phPRD(2024)·2 citations
4. 04*

   Angular correlations in associated top-quark and dark matter production at Large Hadron Collider

   E. Abasov🇷🇺 · E. Boos🇷🇺 · V. Bunichev🇷🇺 · P. Volkov🇷🇺 · G. Vorotnikov🇷🇺 · L. Dudko🇷🇺 · A. Zaborenko🇷🇺 · E. Iudin🇷🇺 · A. Markina🇷🇺 · M. Perfilov🇷🇺

   In the paper, we consider the processes of single top-quark production in association with dark matter particles through the t-channel in simplified models with scalar and pseudoscalar mediators. Within the framework of these models, we analyze the angular correlations that arise in the top quark production process in association with dark matter, comparing them with the production of a top quark in the Standard Model. We consider angular correlations of kinematic variables, which define admissible regions in momentum space and can be used experimentally to distinguish between the fraction of the total momentum carried away by the scalar or pseudoscalar mediator. We demonstrate that scalar mediator significantly changes the rest frame of the well-known angular correlation observable and changes the distributions. In this case, this variable provides clear separation between the SM and DM contribution and can be used to increase the sensitivity of future DM analyses.

   hep-phInt.J.Mod.Phys.A(2024)·6 citations
5. 05*

   Off-shell pion properties: electromagnetic form factors and light-front wave functions

   Jurandi Leão (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo Paulo, São Paulo, SP, Brazil, and Instituto Federal de São Paulo, Caraguatatuba, SP, Brazil)🇧🇷 · J. Pacheco B. C. de Melo (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo Paulo, São Paulo, SP, Brazil)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, Brazil)🇧🇷 · Ho-Meoyng Choi (Department of Physics, Teachers College, Kyungpook National University, Daegu, Korea)🇰🇷 · Chueng-Ryong Ji (Department of Physics, North Carolina State University, Raleigh, NC, USA)🇺🇸

   The off-shell pion electromagnetic form factors are explored with corresponding off-shell light-front wave functions modeled by constituent quark and anti-quark. We apply the Mandelstam approach for the microscopic computation of the form factors relating the model parameters with the pion decay constant and charge radius. Analyzing the existing data on the cross-sections for the Sullivan process, H(e,e',pi)n, we extract the off-shell pion form factor using the relation derived from the generalized Ward-Takahashi identity for the pion electromagnetic current. They are compared with our previous results from exactly solvable manifestly covariant model of a (3+1)-dimensional fermion field theory. We find that the adopted constituent quark model reproduces the extracted off-shell form factor $F_1(Q^2,t)$ from the experimental data within a few percent difference and matches well with our previous theoretical simulation which exhibits a variation of about 10\% for the extracted off-shell pion form factor $g(Q^2,t)$. We also identify the pion valence parton distribution function (PDF) and transverse momentum distribution (TMD) in terms of the light-front wave function and discuss their off-shell properties.

   hep-phnucl-thPRD(2024)·9 citations
6. 06*

   Enhanced tunable cavity development for axion dark matter searches using a piezoelectric motor in combination with gears

   A. K. Yi🇺🇸 · T. Seong🇰🇷 · S. Lee🇰🇷 · S. Ahn🇰🇷 · B. I. Ivanov🇰🇷 · S. V. Uchaikin🇰🇷 · B. R. Ko🇰🇷 · Y. K. Semertzidis🇰🇷

   Most search experiments sensitive to quantum chromodynamics (QCD) axion dark matter benefit from microwave cavities, as electromagnetic resonators, that enhance the detectable axion signal power and thus the experimental sensitivity drastically. As the possible axion mass spans multiple orders of magnitude, microwave cavities must be tunable and it is desirable for the cavity to have a tunable frequency range that is as wide as possible. Since the tunable frequency range generally increases as the dimension of the conductor tuning rod increases for a given cylindrical conductor cavity system, we developed a cavity system with a large dimensional tuning rod in order to increase this. We, for the first time, employed not only a piezoelectric motor, but also gears to drive a large and accordingly heavy tuning rod, where such a combination to increase driving power can be adopted for extreme environments as is the case for axion dark matter experiments: cryogenic, high-magnetic-field, and high vacuum. Thanks to such higher power derived from the piezoelectric motor and gear combination, we realized a wideband tunable cavity whose frequency range is about 42\% of the central resonant frequency of the cavity, without sacrificing the experimental sensitivity too much.

   hep-phhep-exphysics.ins-detJINST(2024)·2 citations
7. 07*

   Review of the low-lying excited baryons ${\Sigma }^{\ast }(1/2^{-})$

   En Wang🇨🇳 · Li-Sheng Geng🇨🇳 · Jia-Jun Wu🇨🇳 · Ju-Jun Xie🇨🇳 · Bing-Song Zou🇨🇳

   Strong empirical and phenomenological indications exist for large sea-quark admixtures in the low-lying excited baryons. Investigating the low-lying excited baryon ${\Sigma }^{\ast }(1/2^{-})$ is important to determine the nature of the low-lying excited baryons. We review the experimental and theoretical progress on the studies of the ${\Sigma }^{\ast }(1/2^{-})$. Although several candidates have received intensive discussions, such as $\Sigma (1620)$ and $\Sigma (1480)$, their existence needs further confirmation. Following the prediction of the unquenched quark models for the ${\Sigma }^{\ast }(1/2^{-})$, many theoretical works suggested the existence of these states in various processes. Future experimental measurements could shed light on the existence of the low-lying excited ${\Sigma }^{\ast }(1/2^{-})$ state.

   hep-phChin.Phys.Lett.(2024)·48 citations
8. 08*

   A quark core-gluon model for heavy hybrid baryons

   Lorenzo Cimino🇧🇪 · Cintia T. Willemyns🇧🇪 · Claude Semay🇧🇪

   Besides the ordinary hadrons, QCD allows the existence of states in which excitations of the gluonic field can play the role of valence particles, either alone in a glueball, or coupled to quarks in a hybrid. So, hybrid baryons, made of three quarks and a gluon, can a priori exist. Till now, there is no experimental evidence for such exotic hadrons but experimental efforts are being made to search for them at CEBAF Large Acceptance Spectrometer. In this work, a hybrid baryon is considered as a two-body system composed of a color octet three-quark core and a gluon, interacting via a QCD-inspired interaction. A semirelativistic potential model is built in which the dominant interaction is a potential simulating the flux tube confinement, and the Casimir scaling is assumed to link interactions between triplet and octet color sources. This picture is similar to the quark-diquark description for baryons. It is chosen in order to take properly into account the helicity of the gluon. Only $cccg$ and $bbbg$ states are considered because the strong mass asymmetry between the quark core and the gluon is expected to favor the formation of the core. As the results for heavy hybrid baryons seem relevant, we consider this paper as a proof of concept which can be extended for the study of light hybrid baryons.

   hep-phPRD(2024)·8 citations
9. 09*

   Revisiting strong-coupling determinations from $e^{+}{e}^{-}$ event shapes

   Guido Bell🇩🇪 · Christopher Lee🇺🇸 · Yiannis Makris🇺🇸 · Jim Talbert🇺🇸 · Bin Yan🇨🇳

   We reassess the theoretical uncertainties of strong-coupling determinations from a global fit to the $e^{+}{e}^{-}$ thrust data, focusing in particular on the scheme dependence associated with the applied renormalon-cancellation prescription and on the choice of scale parameters that are used to estimate higher-order perturbative corrections in all sectors of the calculation.

   hep-ph0 citations
10. 10*

    Prediction of the Dark Fermion Mass using Multicritical-Point Principle

    Yoshiki Matsuoka🇯🇵

    This paper proposes a method to determine the effective potential using the multicritical-point principle (MPP) under the additional scalar field. The MPP is applied to the model in which a singlet dark fermion and a singlet real scalar field are added to the Standard Model (SM) to predict the dark fermion mass. As a result, the dark fermion mass is predicted to be about $901$--$972$ GeV.

    hep-phPLB(2024)·2 citations
11. 11*

    Weak interaction axial form factors of the octet baryons in nuclear medium

    G. Ramalho🇰🇷 · K. Tsushima🇧🇷 · Myung-Ki Cheoun🇰🇷

    We study the axial-vector and the induced pseudoscalar form factors associated with the weak transitions between the octet baryon members in nuclear medium, using a covariant constituent quark model. We extend previous calculations of the axial transition form factors from the vacuum (free space) to the nuclear medium (symmetric nuclear matter). The extension of the model to the nuclear medium takes into account the modifications of the properties of hadrons in the medium (masses and coupling constants), as determined by the quark-meson coupling model. The axial-vector ($G_A$) and the induced pseudoscalar ($G_P$) form factors are evaluated for different values of the nuclear density $\rho$ in terms of the square transfer momentum $q^2=-Q^2$. We conclude that, in general, the $G_A$ and $G_P$ form factors are reduced in the nuclear medium. The reduction is stronger for light baryons and high densities. The medium modifications are milder for the heavier octet baryons, particularly at large $Q^2$. The calculations presented here can be used to estimate the cross sections of neutrino and antineutrino scattering with nucleus, and neutrino and antineutrino scattering with hyperons bound to a nucleus, as well as those in the cores of compact stars.

    hep-phhep-exhep-latnucl-ex+1PRD(2025)·9 citations
12. 12*

    Studying ${\pi }^{+}{\pi }^{-}$ photoproduction beyond Pomeron exchange

    Łukasz Bibrzycki🇵🇱 · Nadine Hammoud🇵🇱 · Vincent Mathieu🇪🇸 · Robert J. Perry🇪🇸 · Alex Akridge🇺🇸 · César Fernández-Ramírez🇪🇸 · Gloria Montaña🇺🇸 · Alessandro Pilloni🇮🇹 · Arkaitz Rodas🇺🇸 · Vanamali Shastry🇺🇸 · Wyatt A. Smith🇺🇸 · Daniel Winney🇩🇪 · Adam P. Szczepaniak🇺🇸

    Forward photoproduction of ${\pi }^{+}{\pi }^{-}$ pairs with invariant mass of the order of $m_{\rho }\sim 770$ MeV is traditionally understood to be produced via Pomeron exchange. Based on a detailed analysis of the CLAS photoproduction data, it is shown that the dynamics of two-pion photoproduction for $|t|\gtrsim 0.5$ GeV${}^2$ cannot be explained by Pomeron exchange alone. This motivates the development of a new theoretical model of two-pion photoproduction which incorporates both two-pion and pion-nucleon resonant contributions. After fitting free parameters, the model provides an excellent description of the low moments of the angular distribution measured at CLAS, and enables an assessment of the relative contributions of particular production mechanisms and an interpretation of the various features of the data in terms of these mechanisms.

    hep-phhep-exPRD(2025)·2 citations
13. 13*

    Photoproduction in general-purpose event generators

    Ilkka Helenius🇫🇮 · Peter Meinzinger🇬🇧 · Simon Plätzer🇦🇹 · Peter Richardson🇬🇧

    We compare the three general-purpose Monte Carlo event generators, HERWIG, PYTHIA, and SHEPRA for jet photoproduction processes in $e^{+}{e}^{-}$ and $ep$ collisions. Due to the lower energy scales probed, photoproduction is particularly sensitive to non-perturbative corrections. In a systematic analysis we disentangle and quantify the differences between the generators in these processes, i.e. contributions from beam remnants, parton showers, multiparton interactions (MPIs), and hadronisation modelling. We outline the default inputs and implementation differences and compare the computations with experimental data from LEP and HERA. We find that all generators provide a decent description of the data within the uncertainties, with particularly good descriptions by the LO-accurate PYTHIA and the NLO-accurate SHERPA. Finally, we also present predictions for the upcoming EIC for jet observables and event shapes and conclude that a modern global refit of the photon parton distributions and dedicated experimental measurements ported to the RIVET framework to constrain non-perturbative parameters are the key prerequisites for precision photoproduction phenomenology at the EIC.

    hep-phSciPost Phys.Comm.Rep.(2026)·4 citations
14. 14*

    Constraining the axial-vector X17 interpretation with ${}^{12}$C data

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

    Recent findings of an unexpected, narrow resonance in the $e^{+}{e}^{-}$ decay spectra of excited states of ${}^8$Be, ${}^4$He and ${}^{12}$C by the ATOMKI collaboration have received considerable experimental and theoretical attention, whereby a new, 17-MeV vector-like or axial-vector-like boson termed X17 was conjectured as an explanation of the anomaly. Further analysis of all existing constraints disfavors a vector X17 scenario. For a similar analysis of the axial-vector scenario, a calculation of the reduced matrix element of a spin-dipole operator between the excited nuclear state ${}^{12}$C(17.23) and the carbon ground state is required. In the present work, we compute the aforementioned reduced matrix element under the assumption that the state ${}^{12}$C(17.23) is well represented by the $2s_{1/2}1p_{3/2}^{-1}$ particle-hole shell-model excitation of the ground state, as supported by experimental data. Within such a framework, our results indicate that, like the vector scenario, the axial-vector interpretation of X17 shows strong tensions with the other existing constraints on the nucleon coupling of a conjectured X17.

    hep-phnucl-thPLB(2024)·10 citations
15. 15*

    Double pion photoproduction off nucleons in covariant chiral perturbation theory

    Kai-Ge Kang🇨🇳 · Xiong-Hui Cao🇨🇳 · De-Liang Yao🇨🇳 · Han-Qing Zheng🇨🇳

    The double pion photoproduction off nucleons near threshold is analyzed in a covariant baryon chiral perturbation theory up to next to leading order, where the $\Delta (1232)$, $N^{\ast }(1400)$ and $\rho (770)$ resonances are included as explicit degrees of freedom. For the process $\gamma p\to {\pi }^{+}{\pi }^{0}n$, the chiral results of total cross sections, invariant-mass distributions and beam-helicity asymmetry are in good agreement with the experimental data within uncertainties. For the process $\gamma p\to {\pi }^0{\pi }^{0}p$, the prediction of total cross section deviates from the existing experimental data. Once the final-state interaction of $\pi \pi$ in the isoscalar S-wave channel is taken into account, a good description of the cross section is achieved. The effect of the Roper resonance always turns out be negligible, and hence can be thrown away in future study of this process.

    hep-phPRD(2024)·3 citations
16. 16*

    Systematic analysis of the form factors of $B_c\to {\eta }_c$, $J/\psi$ and corresponding weak decays

    Guo-Liang Yu🇨🇳 · Bin Wu🇨🇳 · Jie Lu🇨🇳 · Zhi-Gang Wang🇨🇳

    The form factors of $B_c\to {\eta }_c$ and $B_c\to J/\psi$ are analyzed in the framework of three-point QCD sum rules. In these analyses, the contributions of the vacuum condensate terms $⟨g_s^{2}GG⟩$ and $⟨g_s^{3}GGGf⟩$ are considered. In addition, the decay widths and branching ratios of several decay channels are obtained by using the calculated form factors. These decay processes include the nonleptonic decays of $B_c^{-}\to {\eta }_c{\pi }^{-}$, ${\eta }_c{K}^{-}$, ${\eta }_c{\rho }^{-}$, ${\eta }_c{K}^{\ast -}$, $B_c^{-}\to J/\psi {\pi }^{-}$, $J/\psi K^{-}$, $J/\psi {\rho }^{-}$, $J/\psi K^{\ast -}$, and the semileptonic decays of $B_c^{-}\to {\eta }_{c}l\bar{\nu }$, $B_c^{-}\to J/\psi l\bar{\nu }$. These results about the form factors and decay properties of $B_c$ meson provide useful information for us to study the heavy-quark dynamics and find new physics(NP) beyond Standard Model(SM).

    hep-phPLB(2024)·12 citations
17. 17*

    Heavy-to-light form factors to three loops

    Matteo Fael🇨🇭 · Tobias Huber🇩🇪 · Fabian Lange🇨🇭 · Jakob Müller🇩🇪 · Kay Schönwald🇨🇭 · Matthias Steinhauser🇩🇪

    We compute three-loop corrections of $\mathcal{O}({\alpha }_s^3)$ to form factors with one massive and one massless quark coupling to an external vector, axialvector, scalar, pseudoscalar, or tensor current. We obtain analytic results for the color-planar contributions, for the contributions of light-quark loops, and the contributions with two heavy-quark loops. For the computation of the remaining master integrals we use the "expand and match" approach which leads to semi-analytic results for the form factors. We implement our results in a {\tt Mathematica} and a {\tt Fortran} code which allows for fast and precise numerical evaluations in the physically relevant phase space. The form factors are used to compute the hard matching coefficients in Soft-Collinear Effective Theory for all currents. The tensor coefficients at light-like momentum transfer are used to extract the hard function in $\bar{B}\to X_s\gamma$ to three loops.

    hep-phPRD(2024)·12 citations
18. 18*

    Sudakov double logs in single-inclusive hadron production in DIS at small $x$ from the Color Glass Condensate formalism

    Tolga Altinoluk🇵🇱 · Jamal Jalilian-Marian🇺🇸 · Cyrille Marquet🇫🇷

    We investigate the high $Q^2$ (photon virtuality) limit of single-inclusive hadron production in DIS (SIDIS) at small $x$, using the color glass condensate formalism at next-to-leading order. We focus on the ${\Lambda }_{QCD}^2\ll {\mathbf{p}}_h^2\ll Q^2$ kinematic regime where ${\mathbf{p}}_h$ is the produced hadron transverse momentum, and extract the Sudakov double logarithms. We further argue that compatibility between the CGC calculation and TMD factorization at one-loop order can only be achieved if the small-x evolution is kinematically constrained.

    hep-phPRD(2024)·29 citations
19. 19*

    Searching for bound states in the open strangeness systems

    C. W. Xiao🇨🇳 · J. J. Wu🇨🇳

    Inspired by the recent findings of $Z_{cs}$ and $P_{cs}$ states, we investigate the strong interactions of the systems with open strangeness(es) from the light sector to the heavy sector (no beauty quark), where the interaction potential is derived from the vector meson exchange mechanism in $t$- and $u$-channels. In the current work, we discuss all of single channel cases for the open strangeness in the systemic framework, where the resonances $X_0(2866)$, $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ are dynamically generated. Furthermore, there are many new exotics predicted. In addition, the left-hand cut problem in $t$- and $u$-channels is discussed in detail.

    hep-phhep-exEPJA(2025)·4 citations
20. 20*

    Charged pion condensation and color superconductivity phenomena in chirally asymmetric dense quark matter

    T. G. Khunjua🇬🇪 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

    In this paper, the question of the influence of color superconductivity (CSC) on the formation of a phase with condensation of charged pions in dense chirally asymmetric quark matter is studied. We consider it within the framework of the massless NJL model with a diquark interaction channel at zero temperature, but in the presence of baryon ${\mu }_B$, isospin ${\mu }_I$, chiral ${\mu }_5$ and chiral isospin ${\mu }_{I5}$ chemical potentials. It has been shown in the mean-field approximation that in the presence of chiral imbalance, when ${\mu }_5\ne 0$ and/or ${\mu }_{I5}\ne 0$, CSC phenomenon does not hinder the generation of charged pion condensation in dense quark matter even at largest baryon densities attainable in heavy ion collisions experiments and in cores of neutron stars and its mergers. So charged pion condensation in dense quark matter with chiral imbalance predicted earlier is not in a bit suppressed by the presence of CSC, highlighting the resilience of this phase in dense quark matter. This makes phase structure of dense quark matter even more rich, multifaceted and interesting, and shows that pion condensation in dense quark matter is viable phenomenon to be explored, for example, in intermediate energy heavy ion collisions experiments.

    hep-phhep-thPTEP(2025)·6 citations
21. 21*

    Extra-Dimensional Axion Expectations

    Matthew Reece🇺🇸

    Axions arising as modes of higher-dimensional gauge fields are known to offer a compelling solution to the axion quality problem and to naturally arise in string theory. In this context, it is interesting to ask how we would interpret an experimental measurement of the axion decay constant $f$. I give several arguments for, as well as concrete examples in string theory of, the existence in such a model of an axion string with tension of order $2\pi S_{\mathrm{inst}}{f}^2$, where $S_{\mathrm{inst}}$ is the instanton action. Furthermore, in models of this type axion strings are typically fundamental objects (rather than solitons), whose tension is at or above the fundamental cutoff of the theory. As a result, I argue that for an extra-dimensional QCD axion, it is likely that the fundamental cutoff scale lies at most two orders of magnitude above $f$. In addition to these core arguments, this paper begins with a self-contained introduction to the physics of extra-dimensional axions and ends with some comments on axion physics in relation to chiral fermions.

    hep-phhep-thJHEP(2025)·84 citations
22. 22*

    Color Coherence Effects in Dipole-Quark Scattering in the Soft Limit

    Daniel Pablos🇪🇸 · Sergio Sanjurjo🇪🇸

    Color coherence effects play a crucial role in the description of jet evolution at collider experiments. It is well known that the stimulated gluon emission suffered by energetic jets traversing deconfined QCD matter is also affected by color coherence effects. Through multiple soft scatterings with the medium constituents, an antenna will lose its color correlation, causing its legs to behave as independent emitters after the so-called decoherence time. In this work we provide the first computation of the properties of the recoils produced as a result of these soft scatterings between a color coherent dipole and the medium constituents. Our findings reveal that the angular phase-space of these soft recoils is strongly restricted by the opening angle of the dipole itself due to quantum interference effects. In this long wavelength limit, one can effectively consider that interactions take place with each of the legs of the dipole separately, provided that the angular constraints dictated by the corresponding color flow topologies are respected. This is in complete analogy with the case of soft gluon emission in vacuum, where the recoil quark plays the role of the emitted gluon. As a direct phenomenological application we estimate the collisional energy loss rate of a color antenna. Importantly, these results indicate the way in which color coherence effects can be implemented in jet quenching models that account for the recoils from elastic scatterings, improving in this way our description of medium response physics in heavy-ion collisions.

    hep-phnucl-thPRD(2024)·13 citations
23. 23*

    Python4Physics: A physics outreach program

    Raúl Briceño🇺🇸 · Ted Rogers🇺🇸

    We describe a summer outreach program developed to cultivate interest in physics in particular and physical sciences more broadly among high school and early college students using small projects in the Python programming language. We discuss the lessons we learned in the hopes that they will be valuable to other physicists in planning their own outreach efforts. We also provide links to resources and materials from the Python4Physics program, which we hope might be useful in other outreach programs.

    ↳ physics.ed-phhep-lathep-phphysics.soc-ph1 citation
24. 24*

    Consistent Theories for the DESI dark energy fit

    Alessio Notari🇪🇸 · Michele Redi🇮🇹 · Andrea Tesi🇮🇹

    We search for physically consistent realizations of evolving dark energy suggested by the cosmological fit of DESI, Planck and Supernovae data. First we note that any lagrangian description of the standard Chevallier-Polarski-Linder (CPL) parametrization for the dark energy equation of state $w$, allows for the addition of a cosmological constant. We perform the cosmological fit finding new regions of parameter space that however continue to favour dark energy with $w<-1$ at early times, that is challenging to realize in consistent theories. Next, in the spirit of effective field theories, we consider the effect of higher order terms in the Taylor expansion of the equation of state of dark energy around the present epoch. We find that non-linear corrections of the equation of state are weakly constrained, thus opening the way to scenarios that differ from CPL at early times, possibly with $w>-1$ at all times. We present indeed scenarios where evolving dark energy can be realized through quintessence models. We introduce in particular the ramp model where dark energy coincides with CPL at late times and approximates to a cosmological constant at early times. The latter model provides a much better fit than $\Lambda$CDM, and only slightly worse than $w_0{w}_a$CDM, but with the notable advantage of being described by a simple and theoretically consistent lagrangian of a canonical quintessence model.

    ↳ astro-ph.COhep-phJCAP(2024)·85 citations
25. 25*

    Warm Hawking Relics From Primordial Black Hole Domination

    Christopher J. Shallue🇺🇸 · Julian B. Muñoz🇺🇸 · Gordan Z. Krnjaic🇺🇸

    We study the cosmological impact of warm, dark-sector relic particles produced as Hawking radiation in a primordial-black-hole-dominated universe before big bang nucleosynthesis. If these dark-sector particles are stable, they would survive to the present day as "Hawking relics" and modify the growth of cosmological structure. We show that such relics are produced with much larger momenta, but in smaller quantities than the familiar thermal relics considered in standard cosmology. Consequently, Hawking relics with keV-MeV masses affect the growth of large-scale structure in a similar way to eV-scale thermal relics like massive neutrinos. We model their production and evolution, and show that their momentum distributions are broader than comparable relics with thermal distributions. Warm Hawking relics affect the growth of cosmological perturbations and we constrain their abundance to be less than $2\%$ of the dark matter over a broad range of their viable parameter space. Finally, we examine how future measurements of the matter power spectrum can distinguish Hawking relics from thermal particles.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·11 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.