In this work, we study the $$B^+\rightarrow K^+ E_{\textrm{miss}}$$ , $$B^0\rightarrow K^{*0} E_{\textrm{miss}}$$ , and $$\Lambda _b^0\rightarrow \Lambda ^0 E_{\textrm{miss}}$$ decays under three different new physics hypotheses: the heavy new particles, the light neutral vector particles, and the axion-like particles. We find that all three hypotheses can resolve the Belle-II excess, and they can be clearly distinguished by the longitudinal polarization fraction of $$K^*$$ . Furthermore, we discover that the longitudinal polarization fraction of $$\Lambda $$ can be used to distinguish the chirality of the effective operators.

China

Are the new particles heavy or light in $$b \rightarrow s E_{\textrm{miss}}$$ ?

The ALICE Collaboration at the CERN LHC has measured the inclusive production cross section of isolated photons at midrapidity as a function of the photon transverse momentum ( $$p_{\textrm{T}}^{\gamma }$$ ), in Pb–Pb collisions in different centrality intervals, and in pp collisions, at centre-of-momentum energy per nucleon pair of $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ TeV. The photon transverse momentum range is between 10–14 and 40–140 GeV/ $$c$$ , depending on the collision system and on the Pb–Pb centrality class. The result extends to lower $$p_{\textrm{T}}^{\gamma }$$ than previously published results by the ATLAS and CMS experiments at the same collision energy. The covered pseudorapidity range is $$|\eta ^{\gamma } | <0.67$$ . The isolation selection is based on a charged particle isolation momentum threshold $$p_{\textrm{T}}^\mathrm{iso,~ch} = 1.5$$ GeV/ $$c$$ within a cone of radii $$R=0.2$$ and 0.4. The nuclear modification factor is calculated and found to be consistent with unity in all centrality classes, and also consistent with the HG-PYTHIA model, which describes the event selection and geometry biases that affect the centrality determination in peripheral Pb–Pb collisions. The measurement is compared to next-to-leading order perturbative QCD calculations and to the measurements of isolated photons and Z $$^{0}$$ bosons from the CMS experiment, which are all found to be in agreement.

France

India

Switzerland

Italy

South Korea

Slovakia

Germany

Mexico

United States

Norway

Romania

United Kingdom

Brazil

Japan

Poland

Greece

Hungary

Sweden

Peru

Denmark

Measurement of the inclusive isolated-photon production cross section in pp and Pb–Pb collisions at $$\mathbf {\sqrt{\textit{s}_{NN }} = 5.02}$$ TeV

Fast radio bursts (FRBs) can be explained by collapsing axion stars, imposing constraints on the axion parameter space and providing valuable guidance for experimental axion searches. In the traditional post-inflationary model, axion stars could constitute up to $$75\%$$ of the dark matter component, suggesting that some axion stars may exist within the Solar System. Photons with energy half the axion mass can stimulate axion decay. Thus, directing a powerful radio beam at an axion star could trigger its stimulated decay, producing a detectable echo. Using this method, we find it is possible to test the existence of dilute axion stars with maximum masses ranging from $$6.21\times 10^{-12}M_\odot $$ to $$2.61\times 10^{-10}M_\odot $$ , as constrained by FRBs, within the Solar System. The resulting echo from axion stars constrained by FRBs could be detectable by terrestrial telescopes. Detecting such an echo would confirm the existence of axion stars, unravel the mystery of dark matter, and provide key evidence that some FRBs originate from collapsing axion stars. Furthermore, FRBs produced by axion star collapses could serve as standard candles, aiding in the resolution of the Hubble tension. If no echo is detected using this method, it would place constraints on the abundance of dark matter in the form of dilute axion stars with maximum masses in the range of $$6.21\times 10^{-12}M_\odot $$ to $$2.61\times 10^{-10}M_\odot $$ .

Detecting dilute axion stars constrained by fast radio bursts in the Solar System via stimulated decay

In a recent article (Deglmann et al. in Ann Phys (NY) 475:169948, 2025), the authors obtained a static, cylindrically symmetric Anti-de Sitter (AdS) black string (BS) solutions, which are cylindrical generalizations of black holes (BHs), surrounded by a cloud of strings (CS) and the quintessence field (QF), and discussed its properties. In the present study, we present a comprehensive analysis of cylindrically symmetric AdS BSs surrounded by CS and QF. Our analysis yields several significant results. We demonstrate that the presence of CS (parameter $$\alpha $$ ) and QF (parameters $\textit{c}$ and $\textit{w}$) reduces the radius of circular photon orbits (CPO) and BH shadow size, with measurements constrained by Event Horizon Telescope (EHT) observations of Sagittarius A*. We find that time-like particle orbits show increased energy with higher $$\alpha $$ and $\textit{c}$ values. We calculate that C-energy, representing gravitational energy within cylindrical radius, decreases with radial distance but exhibits distinct responses to CS and QF parameters. We observe that scalar perturbation potential increases $\textit{r}$ for specific $$\alpha $$ and $\textit{c}$ values, indicating stronger field-spacetime interactions away from the BS. We determine that Hawking temperature increases linearly with Schwarzschild radius, with parameter-dependent behavior varying based on QF state parameter $\textit{w}$. These results demonstrate how CS and QF significantly modify the geodesic, perturbative, and thermodynamic properties of AdS BS, with potential observational implications for gravitational lensing, accretion disk dynamics, and BH evaporation signatures in future astronomical observations.

Jordan

Türkiye

AdS black strings in a cosmic web: geodesics, shadows, and thermodynamics

Testing gravity theories beyond General Relativity (GR) is crucial for a deeper understanding of fundamental physics, especially in the strong gravitational field regime around astrophysical compact objects. This work examines quasi-periodic oscillations (QPOs) generated by charged particles orbiting magnetized Bocharova–Bronnikov–Melnikov–Bekenstein (BBMB) black holes. We study charged particles’ circular orbits, deriving expressions for energy and angular momentum influenced by scalar and magnetic interactions, and investigate the innermost stable circular orbit (ISCO). Using the relativistic precession (RP) model, we derive the fundamental orbital, radial, and vertical frequencies of charged particle oscillations, highlighting deviations caused by conformal scalar and magnetic interactions. Our analysis shows that the conformally coupled scalar field significantly modifies the spacetime curvature, producing a repulsive gravitational effect that shifts stable orbits outward, thereby reducing the radial oscillation frequency. Using observational QPO data from well-known astrophysical sources-GRS 1915+105, GRO J1655-40, M82 X-1, and Sgr A*-we performed Markov Chain Monte Carlo (MCMC) simulations to constrain black hole mass, scalar coupling, magnetic interaction, and orbital radius parameters. Our results reveal significant deviations from standard General Relativity predictions, offering clear evidence of scalar and magnetic field influences. These findings indicate that scalar and magnetic fields produce observable shifts in QPO frequencies, providing promising observational signatures to test alternative gravitational theories in extreme astrophysical environments.

Uzbekistan

Saudi Arabia

QPOs tests and circular motions of charged particles around magnetized Bocharova–Bronnikov–Melnikov–Bekenstein black holes

In this paper, we fit the $$B\rightarrow D$$ vector transition form factor (TFF) by using the data measured by $\textit{BABAR}$ and Belle Collaborations within Monte Carlo (MC) method. Meanwhile, the $$B\rightarrow D$$ TFF is also calculated by using the QCD light-cone sum rules approach (LCSRs) within right-handed chiral current correlation function. In the TFF, $\textit{D}$-meson leading-twist light-cone distribution amplitude (LCDA) is the most important non-perturbative input parameter, the precise behavior of which is mainly determined by the parameter $$B_{2;D}$$ in the light-cone harmonic oscillator model. Through fitting the TFF, we determine the value $$B_{2;D}=0.445$$ . Then, we present the curve of $\textit{D}$-meson leading-twist LCDA in comparison with other theoretical approaches. Subsequently, the $$B\rightarrow D$$ TFF $$f_{+}^{BD}(q^2)$$ at the large recoil region is $$f_{+}^{BD}(0)=0.648_{-0.063}^{+0.067}$$ , which is compared in detail with theoretical estimates and experimental measurements. Furthermore, we calculated the decay width and branching fractions of the Cabibbo-favored semileptonic decays $$B\rightarrow D\ell ^+\nu _{\ell }$$ , which lead to the results $${\mathcal {B}}(B^0\rightarrow D^-\ell ^+\nu _{\ell }) =(2.10_{-0.38}^{+0.44})\times 10^{-2}$$ and $${\mathcal {B}}(B^+\rightarrow {\bar{D}}^0\ell ^+\nu _{\ell }) =(2.26_{-0.41}^{+0.48})\times 10^{-2}$$ . Finally, we predict the CKM matrix element with two scenarios $$|V_{cb}|_{\textrm{SR}}=41.55_{-4.50}^{+4.91}\times 10^{-3}$$ and $$|V_{cb} |_{\textrm{MC}}=41.47_{-2.66}^{+2.55 }\times 10^{-3}$$ from $$B^0\rightarrow D^-\ell ^+\nu _{\ell }$$ , $$|V_{cb}|_{\textrm{SR}}=40.54_{-3.80}^{+4.33}\times 10^{-3}$$ and $$|V_{cb} |_{\textrm{MC}}=40.46_{-1.38}^{+1.40}\times 10^{-3}$$ from $$B^+\rightarrow {\bar{D}}^0\ell ^+\nu _{\ell }$$ which are in good agreement with theoretical and experimental predictions.

Footprint in fitting $$B\rightarrow D$$ vector form factor and determination for $\textit{D}$-meson leading-twist LCDA

Different processes have been yet considered to investigate the effects of Lorentz symmetry violation and various bounds have been determined for the magnitude of Lorentz violation (LV) coefficients. In the present work we study, for the first time, the effect of Lorentz-violating terms on the fragmentation functions (FFs) of heavy mesons in two distinct cases correspondent to axial and vectorial nonminimal couplings in the theory of quantum chromodynamics (QCD). Our analytical results for heavy meson FFs in the framework of LV can be used to study the effect of Lorentz symmetry violation on hadron production processes in high energy colliders.

Iran

The effect of Lorentz symmetry violation on the hadron fragmentation function

Next-generation megawatt-scale neutrino beams open the way to studying neutrino-nucleus scattering using gaseous targets for the first time. This represents an opportunity to improve the knowledge of neutrino cross sections in the energy region between hundreds of MeV and a few GeV, of interest for the upcoming generation of long-baseline neutrino oscillation experiments. The challenge is to accurately track and (especially) time the particles produced in neutrino interactions in large and seamless volumes down to few-MeV energies. We propose to accomplish this through an optically-read time projection chamber (TPC) filled with high-pressure argon and equipped with both tracking and timing functions. In this work, we present a detailed study of the time-tagging capabilities of such a device, based on end-to-end optical simulations that include the effect of photon propagation, photosensor response, dark count rate and pulse reconstruction. We show that the neutrino interaction time can be reconstructed from the primary scintillation signal with a precision in the range of 1–2.5 ns $$(\sigma )$$ for point-like deposits with energies down to 5 MeV. A similar response is observed for minimum-ionizing particle tracks extending over lengths of a few meters. A discussion on previous limitations towards such a detection technology, and how they can be realistically overcome in the near future thanks to recent developments in the field, is presented. The performance demonstrated in our analysis seems to be well within reach of next-generation neutrino-oscillation experiments, through the instrumentation of the proposed TPC with conventional reflective materials and a silicon photomultiplier array behind a transparent cathode.

Spain

On the determination of the interaction time of GeV neutrinos in large argon gas TPCs

We analyse relevant signals expected at the LHC, assuming that the gluino is the lightest supersymmetric particle (LSP) in the framework of the $$\mu \nu $$ SSM. In this $\textit{R}$-parity violating model, the presence of couplings involving right-handed neutrinos solves simultaneously the $$\mu $$ problem and the accommodations of neutrino masses and mixing angles. We study gluino pair production in quark-antiquark and gluon-gluon collisions. The main decay channels for the gluino LSP are the three-body decays to two quarks and a lepton or a neutrino. In both cases, the leading channels occur for the third family of quarks. We compare the predictions of this scenario with LHC searches for prompt and long-lived particles. To analyse the parameter space we sample the $$\mu \nu $$ SSM for a gluino LSP, paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavour observables. Our results imply a lower limit on the mass of the gluino LSP of about 2600 GeV, and an upper limit for the decay length of about 6 cm.

Argentina

Searching for gluino LSP at the LHC

We have re-examined Mukhanov parametrization for inflationary equation of state, $$1+\omega =\frac{\beta }{({N}+1)^\alpha }$$ , in the light of Planck 2018 results and latest bound of tensor-to-scalar ratio employing Hamilton–Jacobi formalism. We have found that the current observational values of scalar spectral index and tensor-to-scalar ratio can be used efficiently to constrain the model parameters. The recent bound of $$r<0.032$$ has been used to put an upper bound on one of the model parameter. Whereas 1- $$\sigma $$ bound of the scalar spectral index $$0.9607\le n_{_S}\le 0.9691$$ along with the upper bound of tensor-to-scalar ratio provided restriction on the other model parameter $$1.50<\alpha \le 2.20$$ . These bounds however depend on the number of e-foldings still left before the end of inflation and whenever $$1.50<\alpha \le 2.20$$ we can find appropriate values of the other model parameter $$\beta $$ so that the observational predictions are in tune with the latest available inflationary observables. We have further utilized the predictions from forthcoming CMB missions in the likes of CMB-S4 and LiteBIRD in order to obtain bounds on the model parameters. We find that detection of gravity waves would help us constrain the model parameters further. But in the absence of detection of primordial gravity wave signal by these CMB missions may rule out Mukhanov parametrization.