The azimuthal-correlation distributions between electrons from the decays of heavy-flavor hadrons and associated charged particles in Pb–Pb collisions at $$\sqrt{s_{\textrm{NN}}} = 5.02$$ TeV are reported for the 0–10% and 30–50% centrality classes. This measurement provides access to the jet-like correlation observables in the heavy-flavor sector in Pb–Pb collisions. The analysis is performed for trigger electrons from heavy-flavor hadron decays with transverse momentum $$4< p_\textrm{T}^\textrm{e} < 16~\textrm{GeV}/c$$ , considering associated particles within the transverse-momentum range $$1< p_\textrm{T}^\textrm{assoc} < 7$$ $$\textrm{GeV}/c$$ , and a pseudorapidity difference of $$|\Delta \eta |<1$$ between the trigger electron and associated particles. The per-trigger nuclear modification factor ( $$I_\textrm{AA}$$ ) is calculated to compare the near- and away-side peak yields to those in pp collisions at $$\sqrt{s} = 5.02$$ TeV. In 0–10% central collisions, the $$I_\textrm{AA}$$ indicates a hint of enhancement of associated-particle yields with $$p_\textrm{T}<3$$ GeV/$\textit{c}$ on the near side, and a suppression of yields with $$p_\textrm{T}>4$$ GeV/$\textit{c}$ on the away side. The $$I_\textrm{AA}$$ for electron triggers from heavy-flavor hadron decays is compared with that for light-flavor and strange-particle triggers to investigate the dependence on different fragmentation processes and parton-medium dynamics, and is found to be the same within uncertainties.

United States

I. Abualrob

Italy

S. Acharya

Switzerland

G. Aglieri Rinella

L. Aglietta

M. Agnello

N. Agrawal

India

Z. Ahammed

S. Ahmad

Slovakia

I. Ahuja

Indonesia

Z. Akbar

A. Akindinov

Germany

V. Akishina

M. Al-Turany

D. Aleksandrov

B. Alessandro

China

H. Alfanda

Mexico

R. Alfaro Molina

B. Ali

A. Alici

South Korea

A. Alkin

Norway

J. Alme

G. Alocco

T. Alt

A. Altamura

I. Altsybeev

Romania

C. Andrei

United Kingdom

N. Andreou

A. Andronic

E. Andronov

V. Anguelov

F. Antinori

P. Antonioli

N. Apadula

H. Appelshäuser

France

C. Arata

S. Arcelli

R. Arnaldi

Brazil

J. Arneiro

I. Arsene

M. Arslandok

A. Augustinus

R. Averbeck

M. Azmi

Japan

H. Baba

A. Babu

A. Badalà

J. Bae

Y. Bae

Y. Baek

X. Bai

R. Bailhache

Y. Bailung

R. Bala

A. Baldisseri

Poland

B. Balis

S. Bangalia

Z. Banoo

V. Barbasova

F. Barile

L. Barioglio

Greece

M. Barlou

B. Barman

Hungary

G. Barnaföldi

L. Barnby

E. Barreau

V. Barret

L. Barreto

K. Barth

E. Bartsch

N. Bastid

G. Batigne

D. Battistini

B. Batyunya

D. Bauri

Peru

J. Alba

Denmark

I. Bearden

P. Becht

D. Behera

S. Behera

I. Belikov

V. Bella

F. Bellini

R. Bellwied

L. Beltran

Y. Beltran

G. Bencedi

A. Bensaoula

S. Beole

Y. Berdnikov

A. Berdnikova

L. Bergmann

L. Bernardinis

L. Betev

P. Bhaduri

T. Bhalla

A. Bhasin

B. Bhattacharjee

S. Bhattarai

L. Bianchi

Czechia

J. Bielčík

Medium-induced modification of azimuthal correlations of electrons from heavy-flavor hadron decays with charged particles in Pb–Pb collisions at $$\mathbf {\sqrt{s_{\textrm{NN}}} = 5.02}$$ TeV

We investigate the Chern–Simons-like formulation of 3D MMG-like massive gravity models that are “third-way consistent”. Building on previous work on exotic massive gravities, we analyze a class of MMG-like theories characterized by a specific parity structure and an auxiliary field hierarchy. Focusing on the simplest non-trivial case, we solve the full set of field equations, determine the AdS background solutions, compute the central charges of the dual CFT, and perform a linearized analysis to obtain the mass spectrum. Along the chiral line, the linearized mass operator develops a rank-2 Jordan block, signaling logarithmic behavior of massive modes in the dual two-dimensional CFT. At a special degenerate point, this structure is enhanced to a rank-3 Jordan block, giving rise to two logarithmic partners and an ultra-logarithmic sector in the boundary theory.

Türkiye

Büşra Dedeoğlu

Mehmet Ozkan

Özgür Sarıoğlu

Chern–Simons-like formulation of 3D MMG-like massive gravity models

We investigate the cosmological inflation for the Einstein–Hilbert action plus the Higgs potential function and the Gauss–Bonnet term coupled with the Higgs scalar field through a dilaton-like coupling. Then, using the Friedmann–Lemaître–Robertson–Walker metric and considering the appropriate slow-roll parameters, we derive the necessary equations of motion. In the proposed model, since the $\textit{e}$-folding integral cannot be easily solved analytically, we first utilize a well-known Taylor expansion. Then, with a certain range of values derived for the model parameters, utilizing several plots and numerical analysis methods, we obtain results for the tensor-to-scalar ratio and the scalar spectral index that are in good agreement with the latest observational data, particularly from ACT DR6, within the acceptable range of the $\textit{e}$-folding values. Meanwhile, a key aspect of this work, crucial for achieving reliable values of the inflationary observables, lies in the adopted functional forms for the potential and coupling functions. Also, in the absence of the Gauss–Bonnet term, we find that the inflationary observables are roughly the same as the predictions of the chaotic inflation model.

Iran

Zahra Ahghari

Mehrdad Farhoudi

Inflation with Gauss–Bonnet correction and Higgs potential

Observable signatures of black hole thermodynamics remain far from fully explored. Previous works have suggested that thermodynamic phase transitions of black holes could leave imprints on their images. In this work, we demonstrate that richer black hole thermodynamic information can also leave imprints on the resulting images. Using the charged anti-de Sitter black hole as an example, we study the evolution of its images (shadow and accretion-disk images) along isobaric and isothermal processes. We find that the image size evolves monotonically along isobars but becomes nonmonotonic along isotherms. After further considering phase transitions, the image size exhibits a sudden increase in both thermodynamic processes. More importantly, in the isothermal process, the phase transition further results in the emergence of a critical reduced temperature that separates two qualitatively distinct image evolutions. These results show that black hole images can probe not only phase transitions, but also thermodynamic process and temperature.

Lei You

Jinsong Yang

Black hole images as probes of thermodynamic evolution

We study rare three- and four-body kaon decays as a probe of light vector and axial-vector bosons coupled to nonconserved currents. We find that searches for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mi>L</mi></msub><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">(</mo><mi>X</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></math> decays constrain the couplings of light <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> bosons to light quarks to be as small as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>5</mn></mrow></msup><mo stretchy="false">)</mo></math>. The charged-pion modes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">(</mo><mi>X</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mi>L</mi></msub><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mo stretchy="false">(</mo><mi>X</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></math> provide weaker limits, but constrain complementary combinations of couplings to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>, <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"><mi>s</mi></math> quarks at the level of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup><mo stretchy="false">)</mo></math>. Finally, we also find that double emission of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">→</mo><mi>π</mi><mi>X</mi><mi>X</mi></math> decays can provide yet additional constraints on the parameter space of light <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> bosons due to a double <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><msub><mi>m</mi><mi>K</mi></msub><mo>/</mo><msub><mi>m</mi><mi>X</mi></msub><msup><mo stretchy="false">)</mo><mn>2</mn></msup></math> enhancement to the rate. For a 17 MeV boson, these limits add to the known tension between spin-1 bosons coupled to vector and axial-vector currents interpretations of the results of the ATOMKI experiment with meson decay data. Finally, we also comment on negative pion capture on hydrogen and deuterium as a source of light particles and discuss the prospects for testing the 17 MeV boson hypothesis.

Matheus Hostert

Maxim Pospelov

Adrian Thompson

Kaon decay constraints on vector bosons coupled to nonconserved currents

This study presents a comparative analysis of a light dark matter (DM) scenario in the minimal supersymmetric Standard Model (MSSM), the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mn>3</mn></msub></math>-symmetric next-to-minimal supersymmetric Standard Model, and the general next-to-minimal supersymmetric Standard Model (GNMSSM), incorporating constraints from DM relic density, the LUX-ZEPLIN 2024 experiment, Higgs data, and the Large Hadron Collider (LHC). The results suggest that, among the three frameworks, only GNMSSM can naturally accommodate light DM with a mass below 100 GeV. As such, the viable supersymmetry candidate is primarily Singlino-like. One key advantage of the GNMSSM is the effective decoupling between interactions that establish the relic density and those that control direct detection, allowing the model to satisfy all current experimental bounds simultaneously. We further explore two characteristic mass hierarchies in the GNMSSM parameter space, each exhibiting distinct phenomenological behaviors. The first hierarchy, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>S</mi><mo stretchy="false">˜</mo></mover><mo>&lt;</mo><mover accent="true"><mi>B</mi><mo stretchy="false">˜</mo></mover><mo>&lt;</mo><mover accent="true"><mi>H</mi><mo stretchy="false">˜</mo></mover></math> (Singlino-Bino-Higgsino), involves a relatively light Bino and allows the Higgsino mass parameter, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>tot</mi></msub></math>, to be as low as about 200 GeV, naturally yielding light DM at tens of GeV. The dominant annihilation channels are then <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>χ</mi><mo stretchy="false">˜</mo></mover><mn>1</mn><mn>0</mn></msubsup><msubsup><mover accent="true"><mi>χ</mi><mo stretchy="false">˜</mo></mover><mn>1</mn><mn>0</mn></msubsup><mo stretchy="false">→</mo><msub><mi>A</mi><mi>s</mi></msub><msub><mi>A</mi><mi>s</mi></msub></math> in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mn>1</mn></msub></math> scenario and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mover accent="true"><mi>χ</mi><mo stretchy="false">˜</mo></mover><mn>1</mn><mn>0</mn></msubsup><msubsup><mover accent="true"><mi>χ</mi><mo stretchy="false">˜</mo></mover><mn>1</mn><mn>0</mn></msubsup><mo stretchy="false">→</mo><msub><mi>h</mi><mi>s</mi></msub><msub><mi>A</mi><mi>s</mi></msub></math> in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mn>2</mn></msub></math> scenario, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>s</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mi>s</mi></msub></math> denote singlet-dominated <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd Higgs bosons, respectively. The second hierarchy, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>S</mi><mo stretchy="false">˜</mo></mover><mo>&lt;</mo><mover accent="true"><mi>H</mi><mo stretchy="false">˜</mo></mover><mo>&lt;</mo><mover accent="true"><mi>B</mi><mo stretchy="false">˜</mo></mover></math>, corresponds to a heavy Bino. In this case, although the DM phenomenology remains qualitatively similar, LHC constraints require <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>tot</mi></msub><mo>≳</mo><mn>900</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, implying a significant degree of fine-tuning in reproducing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math>-boson mass.

Fei Li

Junjie Cao

Natural realization of tens-of-GeV dark matter in the general NMSSM

We generalize the nature of the so-called beam-dump “ceiling” beyond which the improvement on the sensitivity reach in the search for fast-decaying mediators dramatically slows down, and we point out its experimental implications that motivate tabletop-sized beam-dump experiments for the search. Light (bosonic) mediators are well-motivated new-physics particles, as they can appear in dark-sector portal scenarios and models to explain various laboratory-based anomalies. Due to their low mass and feebly interacting nature, beam-dump-type experiments, utilizing high-intensity particle beams, can play a crucial role in probing the parameter space of such visibly decaying mediators—in particular, the “prompt decay” region, where the mediators feature relatively large coupling and mass. We present a general and semianalytic proof that the ceiling effectively arises in the prompt-decay region of an experiment and show its insensitivity to data statistics, background estimates, and systematic uncertainties, considering a concrete example, the search for axion-like particles interacting with ordinary photons at three benchmark beam facilities: PIP-II at FNAL, and SPS and LHC-dump at CERN. We then identify optimal criteria to perform a cost-effective and short-term experiment to reach the ceiling, demonstrating that very short-baseline compact experiments enable access to the parameter space unreachable thus far.

Doojin Kim

Jaehoon Yu

Jong-Chul Park

Hyunyong Kim

Beam-dump ceiling and its experimental implications: The case of a portable experiment

In this work, we compute the graviton mediated scattering amplitude of a massive spin-2 Fierz-Pauli field with various other massive spin fields, and in the nonrelativistic limit, find out the corresponding two-body gravitational potentials. The massive spin-2 field does not represent gravity here. The theory of gravity is taken to be the usual massless general relativity, and the massive spin-2 field is taken as a test quantum field coupled to gravity via the standard minimal prescription. We first compute the tree level 2-2 scattering of a massive spin-2 field with massive scalar, spin-1, and spin-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> fields with one graviton exchange. Leading Newton potential, as well as the subleading spin or polarization dependent terms at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mi>G</mi><mo stretchy="false">)</mo></math> have been computed. We also consider the next to the leading order [<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mi>G</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>] scattering of the massive spin-2 field with a massive scalar, and demonstrate the spin independent, spherically symmetric leading part of the two body gravitational potential. The present paper can be considered as an attempt to compute the gravitational potential in the context of a higher spin field theory.

Avijit Sen Majumder

Sourav Bhattacharya

Scattering of massive spin-2 field via graviton exchanges with different spin fields and the long range gravitational potential

Hadronic electromagnetic form factors and radiative decay properties offer a crucial window into the nonperturbative dynamics of quantum chromodynamics (QCD). In this work, we employ the light-cone sum rules (LCSR) method to systematically investigate the M1 radiative decay of vector mesons. Our study covers processes including <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mrow><mo>*</mo><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>−</mo></msup><mi>γ</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><mo stretchy="false">→</mo><mi>D</mi><mi>γ</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><mo stretchy="false">→</mo><mi>B</mi><mi>γ</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mrow><mo>*</mo><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mi>γ</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>s</mi><mo>*</mo></msubsup><mo stretchy="false">→</mo><msub><mi>B</mi><mi>s</mi></msub><mi>γ</mi></math>, and further extends to the excited charmonium state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math>. Our calculations yield decay widths for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>*</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> that are in excellent agreement with experimental data. For the charm and bottom meson decays, where precise measurements are lacking, we provide theoretical predictions and compare them with other theoretical approaches. Most notably, our analysis reveals a universal linear dependence of the decay width on a function A(x) in the logarithmic coordinate system, which originates from the two-body decay dynamics and the ratio of the initial and final state decay constants. This relationship holds for the ground state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">→</mo><mi>P</mi><mi>γ</mi></math> processes here and suggests a broader applicability to radiative decays of ground-state vector mesons.

Zhi Jun Wang

Russia

Di Gao

Kai Kai Zhang

Yuan Yuan Ma

Yan Jun Sun

Radiative decays of vector mesons with light-cone sum rules

Recent Belle II data on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msub><mi>E</mi><mrow><mi>miss</mi></mrow></msub></math> show an excess consistent with a two-body decay involving a light invisible particle with mass around 2.1 GeV. We present a UV-complete explanation based on a Higgsed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mo>′</mo></msup></math> gauge symmetry with a light vector boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> and a vectorlike top partner, which naturally enhances <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi></math> transitions. While the minimal model can reproduce the required <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mi>Z</mi><mo>′</mo></msup></math> rate, it is excluded by LHCb searches for resonant dimuon decays due to unavoidable loop-induced couplings of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> to charged leptons. We show that a minimal extension with an additional light <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mo>′</mo></msup></math>-charged singlet fermion allows <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> to decay dominantly invisibly, evades existing constraints coming also from dark photon and collider searches as well as Higgs measurements, and can simultaneously account for the Belle II excess and the observed dark matter abundance through resonant thermal freeze-out.

Slovenia

Patrick D. Bolton

Jernej F. Kamenik

Spain

Martín Novoa-Brunet

Dark light shining on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msub><mrow><mi>E</mi></mrow><mrow><mrow><mi>miss</mi></mrow></mrow></msub></mrow></math>