A Monte Carlo generator of high energy cosmic ray interactions, relying on a very basic and transparent theoretical formalism, in the framework of the Reggeon field theory, is presented. The main motivation for our work is to provide a new cosmic ray interaction model characterized by relatively transparent physics, sufficient parameter freedom, and a high computational efficiency, which can be easily managed by external users, including a retuning of the model parameters. Such a model can be used for studying potential modifications of the interaction treatment, necessary for describing particular sets of data on extensive air showers initiated by high energy cosmic rays, at a microscopic level, thereby keeping a consistency with general restrictions, like the unitarity, energy-momentum and charge conservation, and Lorentz and isospin invariance. Importantly, this should allow one to study a compatibility of such modifications with relevant accelerator data. The model results for particle production and for basic extensive air shower characteristics are presented and discussed.

Sergey Ostapchenko

Tanguy Pierog

Günter Sigl

Basic model for high energy cosmic ray interactions

We present a set of <math altimg='si2.svg'><mrow><mi>&#8467;</mi><mo linebreak='goodbreak'>+</mo><mn>3</mn></mrow></math> simple differential operators and prove that they annihilate an &#8467;-loop generic mass banana integral in dimensional regularization. We study the singular locus of the ideal generated by these operators and show that it is contained in the set of Landau singularities of the first and second type. Through the Macaulay matrix method, we calculate the corresponding holonomic rank up to <math altimg='si3.svg'><mrow><mi>&#8467;</mi><mo linebreak='goodbreak'>=</mo><mn>8</mn></mrow></math>, obtaining <math altimg='si4.svg'><mrow><msup><mn>2</mn><mrow><mi>&#8467;</mi><mo>+</mo><mn>1</mn></mrow></msup><mo linebreak='goodbreak'>&#8722;</mo><mn>1</mn></mrow></math>, which agrees with the number of master integrals for the generic mass banana integrals. Based on these findings, we conjecture that the proposed operators generate the annihilating ideal for the generic mass banana integrals in dimensional regularization.

Italy

Wojciech Flieger

D-ideal of generic mass banana integrals in dimensional regularization

We apply the light-cone QCD sum rules with chiral currents to compute transition form factors of the semileptonic decay of the charmed and bottom scalar mesons <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>/</mo><mi>B</mi></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo><msup><mi>l</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>l</mi></msub></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mi>l</mi><mo>=</mo><mi>e</mi><mo>,</mo><mi>μ</mi><mo stretchy="false">)</mo></mrow></math>, where the scalar meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> are firstly regarded as two quark states, and contributions from the tetraquark component are then added via proper modulation of four distribution amplitudes considered. The obtained transition form factors and branching fraction are free of the contribution from the light-cone distribution amplitudes at the level of twist-three and two simple relations connecting their form factors are obtained. Our computations indicates that the decay branch fractions are on the margin of the measurements reported by the Beijing Spectrometer III in the pure two-quark scenario and are in good agreement with observations when tetraquark component is considered.

China

Di Gao

JiangShan Lan

Duojie Jia

Xingbo Zhao

Yanjun Sun

Transition form factors for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>/</mo><mi>B</mi></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> from light-cone QCD sum rules

We consider an $$\mathcal{N}=1$$ nonrenormalizable supersymmetric gauge theory with the superpotential quartic in the chiral matter superfields. With the help of the Slavnov’s higher covariant derivative regularization it is demonstrated that (in the lowest nontrivial order) the leading power divergent quantum correction to the gauge coupling constant is given by an integral of double total derivatives with respect to the loop momenta. The result obtained after calculating this integral turned out to be proportional to the corresponding quantum correction to the kinetic term of the matter superfields. More exactly, in the considered approximation the quadratically divergent contributions to the gauge coupling and to the kinetic term of the chiral matter superfields are related by an equation analogous to the exact NSVZ $$\beta $$ -function for the renormalizable case.

France

Ali Lakhal

Russia

Konstantin Stepanyantz

Relation between leading divergences in nonrenormalizable 4$\textit{D}$ supersymmetric theories

A new model based on the relativistic Boltzmann equation in the isotropization time approximation is developed to investigate the collective behavior of the quark-gluon plasma produced in high-energy heavy-ion collisions. The equation is solved in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>2</mn><mo>)</mo><mi mathvariant="normal">D</mi></mrow></math> (two spatial and two momentum-space dimensions). This framework couples preequilibrium dynamics with hydrodynamic evolution to simulate the dynamics of quasiparticle evolution. A numerical scheme based on the method of characteristics enables the evolution to begin from a specified initial Boltzmann distribution. In this work, the spatial structure of the initial distribution is modeled using the Trento framework. Our results show that a medium initialized at <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>τ</mi><mn>0</mn></msub></math> on the order of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>1</mn><mspace width="0.16em"></mspace><mi>fm</mi><mo>/</mo><mi>c</mi></mrow></math> with a small shear viscosity to entropy density ratio (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.008</mn></mrow></math>) evolves consistently with hydrodynamic simulations, such as those performed using the vish2+1 code, while discrepancies arise for a medium with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.8</mn></mrow></math>. Furthermore, when initialized with a highly anisotropic momentum distribution in the longitudinal direction at early times, the system exhibits spatially nonuniform thermalization in the transverse plane, leading to the emergence of a nontrivial hypersurface that marks the onset of hydrodynamic applicability. Finally, we compute the <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>-spectra for a nonfluctuating initial condition using the hybrid version of CoMBolt-ITA. In this hybrid setup, the description is switched from quasiparticles to hadrons, and UrQMD is used to model the hadron gas dynamics. We compare these results with those obtained from the hybrid vish2+1 initialized within the same setup. For a small shear viscosity, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.08</mn></mrow></math>, the two results show a good level of consistency, whereas for a larger value, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.8</mn></mrow></math>, a noticeable discrepancy emerges.

Germany

S.F. Taghavi

Iran

S.M.A. Tabatabaee Mehr

F. Taghinavaz

<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mn>2</mn><mo>+</mo><mn>2</mn><mo>)</mo><mi mathvariant="normal">D</mi></mrow></math> collective model based on a relativistic Boltzmann equation in the isotropization-time approximation: CoMBolt-ITA

The capability of the ALICE@LHC and STAR@RHIC experiments to reconstruct <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> mesons has enabled femtoscopic correlation measurements of open-charm mesons in both small and large systems. In this work, we present a theoretical calculation of the correlation functions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> mesons with nucleons, based on the Koonin-Pratt formalism. We employ an effective Lagrangian to model the interaction between charmed mesons and baryons and apply the TROY formalism to obtain the off-shell <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>-matrix in coupled channels, incorporating the effect of the Coulomb interaction when the pair involves two charged particles. The resulting full coupled-channel wave function is inserted into the Koonin-Pratt equation with channel weights derived from a thermal model. Additionally, we compute the correlation functions using the Lednický-Lyuboshitz approximation with low-energy scattering parameters extracted from the unitarized amplitudes. We compare these two approaches and provide predictions for different correlated pairs. Our results can be tested against current and future experimental data from the ALICE and STAR Collaborations in both proton-proton and heavy-ion collisions.

Spain

Mikel F. Barbat

Juan M. Torres-Rincon

Àngels Ramos

Laura Tolos

Femtoscopy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>D</mi><mi>N</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mi>N</mi></math> systems

In light of recent precision measurements from BESIII, we reanalyze the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>,</mo><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup></math> transition form factors using quantum chromodynamics (QCD) light-cone sum rules, incorporating high-twist contributions and well-established next-to-leading-order QCD corrections. Our analysis confirms the chiral enhancement effect arising from twist-3 light-cone distribution amplitudes of the pseudoscalar mesons, and demonstrates a rapid convergence of the operator product expansion. The resulting high-accuracy form factors enable us to determine the optimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>−</mo><msup><mi>η</mi><mo>′</mo></msup></math> mixing parameters from the precise experimental data for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>,</mo><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> (with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo><mo>=</mo><mi>e</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>μ</mi></mrow></math>) differential decay rates. We find that the BESIII data strongly favor a set of mixing parameters, characterized by small decay constants and a large mixing angle, in the quark flavor basis. Notably, the light-cone-sum-rule predictions for the decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, induced by weak <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi><mo stretchy="false">→</mo><mi>d</mi></math> current, reach a precision comparable to the BESIII experimental results. Nevertheless, further refined measurements and more accurate form-factor determinations will be essential to scrutinize the potential role of gluonic components in charmed meson semileptonic decays.

Xiao-En Huang

Shan Cheng

De-Liang Yao

Semileptonic decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mrow><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub><mo stretchy="false">→</mo><msup><mi>η</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> from QCD light-cone sum rules revisited

We extend the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>κ</mi></math>-symmetry analysis of supersymmetric D-brane probes in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>2</mn></msub><mo>×</mo><msup><mi mathvariant="bold">S</mi><mn>2</mn></msup></math> attractor geometry, originally performed by Simons, Strominger, Thompson, and Yin to also include stationary—but nonstatic—worldlines carrying angular momentum along the 2-sphere. We demonstrate that certain special trajectories, with fixed radius and orbital velocity, solve the equations of motion and moreover satisfy a supersymmetry preserving condition, thus defining new <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mfrac><mn>1</mn><mn>2</mn></mfrac></math>-BPS configurations. Furthermore, these classical paths are shown to saturate a lower bound for the Hamiltonian generating global time translations, with the corresponding minimal energy depending on a generalized angular momentum vector <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="bold-italic">J</mi></mrow></math>. The direction of the latter, in turn, determines exactly which supercharges remain unbroken. Our results reveal a richer spectrum of (multiparticle) supersymmetric states in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>×</mo><msup><mrow><mi mathvariant="bold">S</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>, which can be organized into distinct selection sectors labeled by the conserved <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> charges. This construction has direct applications in black hole microstate counting, the analysis of probe dynamics, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>2</mn></msub><mo>/</mo><msub><mi>CFT</mi><mn>1</mn></msub></math> holography.

United States

Alberto Castellano

Carmine Montella

Matteo Zatti

Supersymmetric D-brane probes in 4D <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>×</mo><msup><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> attractors

Since 2019, the Extreme Energy Events (EEE) Project has installed three muon detection stations at the Svalbard Islands ( $$78.9^{\circ } \hbox {N}$$ latitude), employing scintillator-based detectors. This initiative represents the first systematic effort to monitor cosmic-muons rates at high geomagnetic latitudes beyond the Arctic Circle, with the objective of improving our understanding of cosmic-ray propagation and modulation in polar regions. The present study analyses temporal variations in the muon detection rates over a six-year period (2019–2025), including the study of periodic modulations and underlying trends in the observed rates.

M. Abbrescia

C. Avanzini

L. Baldini

R. Baldini Ferroli

G. Batignani

M. Battaglieri

E. Bossini

F. Carnesecchi

D. Cavazza

C. Cicalò

L. Cifarelli

F. Coccetti

E. Coccia

A. Corvaglia

A. Caro

D. Gruttola

S. Pasquale

L. Galante

M. Garbini

L. Ghezzer

I. Gnesi

F. Gramegna

Norway

E. Gramstad

S. Grazzi

E. Haland

Switzerland

D. Hatzifotiadou

P. Rocca

R. Liotino

G. Mandaglio

A. Margotti

G. Maron

M. Mazziotta

A. Mulliri

R. Nania

F. Noferini

F. Nozzoli

F. Ould-Saada

F. Palmonari

M. Panareo

M. Panetta

R. Paoletti

C. Pellegrino

L. Perasso

O. Pinazza

C. Pinto

S. Pisano

K. Piscicchia

L. Quaglia

M. Rasà

F. Riggi

G. Righini

C. Ripoli

M. Rizzi

B. Sabiu

G. Sartorelli

E. Scapparone

M. Schioppa

G. Scioli

A. Scribano

M. Selvi

A. Shtimermann

M. Taiuti

A. Trifirò

M. Trimarchi

C. Vistoli

L. Votano

M. Williams

A. Zichichi

R. Zuyeuski

Measurement of the cosmic-ray rate over the period 2019–2025 at very high latitude (78.9°N)

We investigate the nucleon and pion gravitational $\textit{D}$-form factors, by fitting a $\textit{σ}$/$\textit{f}$ (500)-meson pole, together with a background term, to lattice data at $\textit{m}$ ≈ 170 MeV. We find that the fitted residues are compatible with predictions from dilaton effective theory. In this framework, the $\textit{σ}$-meson takes on the role of the dilaton, the Goldstone boson of spontaneously broken scale symmetry. These results support the idea that QCD may be governed by an infrared fixed point and offer a physical interpretation of the $\textit{D}$-form factor (or $\textit{D}$-term) in the soft limit.

not found

Roy Stegeman

Roman Zwicky

Gravitational $\textit{D}$-form factor: the $\textit{σ}$-meson as a dilaton confronted with lattice QCD data I