<p>The solar steady emission in gamma rays is due to the interactions of Galactic cosmic rays with the solar atmosphere and with the low-energy solar photon field via inverse Compton scattering. The emission is sensitive to the magnetic field nearby the Sun and to the cosmic-ray transport in the magnetic field in the inner Solar System. Modeling the inverse Compton emission in the presence of a magnetic field is, therefore, crucial to better interpret the observations. In a previous work, we have presented a comprehensive calculation of the secondary productions due to the collision of cosmic rays with the solar atmosphere in the presence of magnetic fields. In this paper, we present a general approach to calculate the (anisotropic) inverse Compton scattering in a 3D Monte Carlo simulation, also in the presence of magnetic and electric fields. After a short review of the scattering process of photons with electrons, examples of inverse Compton emission are presented, including the predictions for the Sun.</p>

Italy

M.N. Mazziotta

3D Monte Carlo calculation of the inverse Compton emission from the Sun and stars in the presence of magnetic and electric fields

The discovery of solar neutrinos confirmed that the inner workings of the Sun generally match our theoretical understanding of the fusion process. Solar neutrinos have also played a role in discovering that neutrinos have mass and that they oscillate. We combine the latest solar neutrino data along with other oscillation data from reactors to determine the Sun's density profile. We derive constraints given the current data and show the anticipated improvements with more reactor neutrino data from JUNO constraining the true oscillation parameters and more solar neutrino data from DUNE which should provide a crucial measurement of <italic>hep</italic> neutrinos.

United States

Peter B. Denton

Charles Gourley

Determining the density of the sun with neutrinos

In this study, we investigate the $R^2$ corrections to the dissociation of heavy quarkonium in the Gauss-Bonnet gravitational background. We analyze the impact of the Gauss-Bonnet parameter $\lambda_{\rm GB}$ on the spectral function of charmonium and bottomonium and examine the effect of $\lambda_{\rm GB}$ on the dissociation of heavy quarkonium. Our results show that $\lambda_{\rm GB}$ reduces the peak height and increases the peak width of the spectral function, suggesting that $\lambda_{\rm GB}$ enhances the dissociation of heavy quarkonium. We also discuss the variation in the dissociation of heavy quarkonium with the ratio of shear viscosity to entropy density and observe that the dissociation is easier in more perfect plasma. Additionally, we observe that the temperature decreases the peak height and widens the peak, thereby accelerating the dissociation.

China

Zhou-Run Zhu

Manman Sun

Rui Zhou

Jinzhong Han

$\textit{R}$ $^{2}$ corrections to holographic heavy quarkonium dissociation * Rui Zhou supported by the Science and Technology Development Plan Project of Henan Province, China (242102230085), the National Natural Science Foundation of China (12404470), the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023017). Manman Sun supported by the National Natural Science Foundation of China (12305076). Zhou-Run Zhu supported by the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023018)

<p>The Sun is not quite a perfect sphere, and its oblateness, thought to be induced through its rotation, has been measured using optical observations of its radius. Its gravitational quadrupole moment can then be deduced using solar models, or through helioseismology, and it can also be determined from measurements of its gravitational effects on Mercury’s orbit. The various assessments do not appear to agree, with the most complete and precise orbital assessments being in slight excess of other determinations. This may speak to the existence of a nonluminous disk or ring, where we also note evidence for a circumsolar dust ring within Mercury’s orbit from the Solar TErrestrial RElations Observatory (STEREO) mission. Historically, too, a protoplanetary disk may have been key to reconciling the Sun’s metallicity with its neutrino yield. The distribution of the nonluminous mass within Mercury’s orbit can modify the relative size of the optical and orbital quadrupole moments in different ways. We develop how we can use these findings to limit the mass of a dark disk, ring, or halo in the immediate vicinity of the Sun, and we note how future observational studies of the inner Solar System can not only refine these constraints but can also help to identify and to assess the mass of its dark-matter component.</p>

Brazil

Gustavo F.S. Alves

Susan Gardner

Pedro Machado

Mohammadreza Zakeri

Does the Sun have a dark disk?

Millicharged dark matter particles can be efficiently captured by the Sun, where they annihilate into tau leptons, leading to the production of high-energy neutrinos. In contrast to the Earth, the high temperature of the Sun suppresses the fraction of millicharged particles that are bound to nuclei, allowing for potentially high annihilation rates. We recast existing constraints from the IceCube Neutrino Observatory and use this information to place new limits on the fraction of the dark matter that is millicharged. This analysis excludes previously unexplored parameter space for masses of <math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>∼</mo><mo>(</mo><mn>5</mn><mi>–</mi><mn>100</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, charges of <math><mrow><msub><mrow><mi>q</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>∼</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><mi>–</mi><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math>, and fractional abundances as small as <math><mrow><msub><mrow><mi>f</mi></mrow><mrow><mi>DM</mi></mrow></msub><mo>∼</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math>.

Asher Berlin

Dan Hooper

High-energy neutrinos from millicharged dark matter annihilation in the Sun

By using the analytic continuation method, a polarized Polykov-loop potential at finite real angular velocity is constructed from the lattice results at finite imaginary angular velocity. The chiral and deconfinement phase transitions under rotation have been simultaneously investigated in the polarized-Polyakov-loop Nambu–Jona-Lasinio (PPNJL) model. It is observed that both critical temperatures of deconfinement and chiral phase transition increase with the angular velocity, which is in consistent with lattice results. The spin alignment of vector meson has the negative deviation of <math><msub><mi>ρ</mi><mn>00</mn></msub><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn></math> under rotation, and the deviation in the PPNJL model is much more significant than that in the NJL model and the quark coalescence model, which revealing the important role of rotating gluons on the quark polarization.

Fei Sun

Jingdong Shao

Rui Wen

Kun Xu

Mei Huang

Chiral phase transition and spin alignment of vector mesons in the polarized-Polyakov-loop Nambu–Jona-Lasinio model under rotation

The exploration of the parameter space of axion and axion-like particle dark matter is a major aim of the future program of astroparticle physics investigations. In this context, we present a possible strategy that focuses on detecting radio emissions arising from the conversion of dark matter axions in the Sun's magnetic field, including conversion in sunspots. We demonstrate that near-future low-frequency radio telescopes, such as the SKA Low, may access regions of unexplored parameter space for masses <math><msub><mrow><mi>m</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>≲</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> eV.

Elisa Todarello

Marco Regis

Marco Taoso

Spain

Maurizio Giannotti

Jaime Ruz

Julia K. Vogel

The Sun as a target for axion dark matter detection

At leading order in the QCD coupling constant, we compute the energy loss per traveling distance of a heavy quark <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi></math> from elastic scattering off thermal quarks and gluons at a temperature <math><mi>T</mi></math>, including the thermal perturbative description of soft scatterings (<math><mo>−</mo><mi>t</mi><mo>&lt;</mo><mo>−</mo><msup><mi>t</mi><mo>*</mo></msup></math>) and a perturbative QCD-based calculation for hard collisions (<math><mo>−</mo><mi>t</mi><mo>&gt;</mo><mo>−</mo><msup><mi>t</mi><mo>*</mo></msup></math>). Within this soft-hard factorization model, we find that the full results of <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi></math> behaves a mild sensitivity to the intermediate cutoff <math><msup><mi>t</mi><mo>*</mo></msup></math>, supporting the validity of the soft-hard approach within the temperature region of interest. We rederive the analytic formula for <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi></math> in the high-energy approximation, <math><msub><mi>E</mi><mn>1</mn></msub><mo>≫</mo><msubsup><mi>m</mi><mn>1</mn><mn>2</mn></msubsup><mo>/</mo><mi>T</mi></math>, where <math><msub><mi>E</mi><mn>1</mn></msub></math> is the injected heavy quark energy and <math><msub><mi>m</mi><mn>1</mn></msub></math> is its mass. It is realized that the soft logarithmic contribution, <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi><mo>∝</mo><mi>ln</mi><mo>(</mo><mo>−</mo><msup><mi>t</mi><mo>*</mo></msup><mo>/</mo><msubsup><mi>m</mi><mi>D</mi><mn>2</mn></msubsup><mo>)</mo></math>, arises from the <math><mi>t</mi></math>-channel scattering off thermal partons, while the hard logarithmic term, <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi><mo>∝</mo><mi>ln</mi><mo>[</mo><msub><mi>E</mi><mn>1</mn></msub><mi>T</mi><mo>/</mo><mo>(</mo><mo>−</mo><msup><mi>t</mi><mo>*</mo></msup><mo>)</mo><mo>]</mo></math>, stems from the <math><mi>t</mi></math>-channel scattering off thermal partons, and the one <math><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi><mo>∝</mo><mi>ln</mi><mo>(</mo><msub><mi>E</mi><mn>1</mn></msub><mi>T</mi><mo>/</mo><msubsup><mi>m</mi><mn>1</mn><mn>2</mn></msubsup><mo>)</mo></math> comes from the <math><mi>s</mi></math>- and <math><mi>u</mi></math>-channel scattering off gluons. The sum of these contributions cancels the <math><msup><mi>t</mi><mo>*</mo></msup></math>-dependence as observed in the full result. The mass hierarchy is observed <math><mrow><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi><mo>(</mo><mtext>charm</mtext><mo>)</mo><mo>&gt;</mo><mi>d</mi><mi>E</mi><mo>/</mo><mi>d</mi><mi>z</mi><mo>(</mo><mtext>bottom</mtext><mo>)</mo></mrow></math>. Our full results are crucial for a better description of heavy quark transport in QCD medium, in particular at low and moderate energy. We also calculate the energy loss by imposing the Einstein’s relationship. The related results appear to be systematically larger than that without imposing the Einstein’s relationship.

Jiazhen Peng

Kewei Yu

Shuang Li

Wei Xiong

Wei Xie

Unraveling the collisional energy loss of a heavy quark in a quark-gluon plasma

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.

Austria

Xiaoyong Chu

Raghuveer Garani

Camilo García-Cely

CERN

Belgium

Thomas Hambye

Dark matter bound-state formation in the Sun

The nuclear reaction network within the interior of the Sun is an efficient MeV physics factory and can produce long-lived particles generic to dark sector models. In this work we consider the sensitivity of satellite instruments, primarily the RHESSI spectrometer, that observe the quiet Sun in the MeV regime where backgrounds are low. We find that quiet Sun observations offer a powerful and complementary probe in regions of parameter space, where the long-lived particle decay length is longer than the radius of the Sun and shorter than the distance between the Sun and Earth. We comment on connections to recent model-building work on heavy neutral leptons coupled to neutrinos and high-quality axions from mirror symmetries.