This paper investigates the production of Z bosons in proton-lead collisions at a center of mass energy of <math altimg='si8.svg'><mrow><msqrt><mi>s</mi></msqrt><mo linebreak='goodbreak'>=</mo><mn>8.16</mn></mrow></math> TeV, utilizing various transverse momentum dependent parton distribution functions (TMDs), including the leading order Martin-Ryskin-Watt (LO-MRW), next-to-leading order MRW (NLO-MRW), and parton branching (PB) approaches. By comparing theoretical predictions with experimental data from the CMS collaboration, we assess the performance of these TMD models across different kinematic regions. Our analysis reveals that while both LO-MRW and NLO-MRW models generally align well with experimental data, the LO-MRW model tends to overestimate in certain kinematic regions. The NLO-MRW model, with its strong ordering constraint, provides better agreement in these areas. This study highlights the impact of different impositions of angular and strong ordering constraints in the LO-MRW and NLO-MRW approaches in describing Z boson production.

Iran

S. Rezaie

Türkiye

K. Azizi

Z boson production in proton-lead collisions: A study utilizing MRW nuclear TMDs

The difference in the proton and neutron separation energies ( <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>) of the weakly bound <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C ground state is -19.86 MeV, an extreme value. Data from intermediate-energy heavy-ion induced (HI-induced) knockout reactions on nuclei spanning <math altimg='si20.svg'><mrow><mo>&#8722;</mo><mn>20</mn><mo>&#8818;</mo><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi><mo>&#8818;</mo><mo>+</mo><mn>20</mn></mrow></math> MeV, suggest that the degree to which single-particle strength is quenched, <math altimg='si13.svg'><msub><mi>R</mi><mrow><mi mathvariant='normal'>s</mi></mrow></msub></math>, has a negative correlation with <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>, decreasing from unity around <math altimg='si21.svg'><mrow><mo>&#8722;</mo><mn>20</mn></mrow></math> MeV to around 0.2 at <math altimg='si22.svg'><mrow><mo>+</mo><mn>20</mn></mrow></math> MeV. For the <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C ground state ( <math altimg='si23.svg'><mrow><msub><mi>R</mi><mi>s</mi></msub><mo linebreak='goodbreak'>=</mo><mn>0.96</mn><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow></math> in HI-induced knockout), contrasting results have recently been obtained via the neutron-adding transfer reaction, which reveal a value of <math altimg='si24.svg'><mrow><msub><mi>R</mi><mi>s</mi></msub><mo linebreak='goodbreak'>=</mo><mn>0.64</mn><mrow><mo>(</mo><mn>15</mn><mo>)</mo></mrow></mrow></math>, similar to the value observed at modest <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math> and more extreme values of <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math> with reaction probes other than HI knockout. In order to explore the any potential differences between <math altimg='si25.svg'><mrow><mi>a</mi><mi>d</mi><mi>d</mi><mi>i</mi><mi>n</mi><mi>g</mi></mrow></math> and <math altimg='si26.svg'><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>o</mi><mi>v</mi><mi>i</mi><mi>n</mi><mi>g</mi></mrow></math> processes in transfer reactions at extreme <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>, single-neutron removal transfer reactions on <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C were performed at 7.1 MeV/u in inverse kinematics. The removal of a valence neutron in 2 <math altimg='si19.svg'><msub><mi>s</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math> orbit using both ( <math altimg='si7.svg'><mrow><mi>p</mi><mo>,</mo><mi>d</mi></mrow></math>) and ( <math altimg='si8.svg'><mrow><mi>d</mi><mo>,</mo><mi>t</mi></mrow></math>) reactions shows consistent quenching factors and agrees with those from the neutron-adding reaction. The present results, which can be compared with neutron knockout reaction, suggest that correlations, represented by the quenching factor, show limited dependence on neutron-proton asymmetry under the most extreme asymmetry conditions so far achieved in transfer reactions.

China

Y.C. Jiang

United States

J. Chen

B.P. Kay

C.R. Hoffman

T.L. Tang

I.A. Tolstukhin

M.R. Xie

J.G. Li

N. Michel

M.L. Avila

Spain

Y. Ayyad

D. Bazin

United Kingdom

S. Bennett

J.A. Clark

Switzerland

S.J. Freeman

H. Jayatissa

G. Li

W.P. Liu

J.L. Lou

A. Munoz-Ramos

C. Müller-Gatermann

T. Nathan

D. Santiago-Gonzalez

D.K. Sharp

Y.P. Shen

A.H. Wuosmaa

C.X. Yuan

Quenching of single-particle strength inferred from nucleon-removal transfer reactions on <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C

In this article, the potential of water Cherenkov detectors equipped with multi-PMT modules for background-free upward-going neutrino detection and improved direction reconstruction is demonstrated. By analyzing signal time traces with transformer-based models, significant improvements in angular resolution are achieved compared to previous designs with larger PMTs. These detectors enable the reconstruction of neutrino directions with resolutions of approximately $$10^\circ $$ in azimuth and $$7^\circ $$ in zenith for high-signal events, corresponding to an overall opening angle of approximately $$10^\circ .$$ This design reduces saturation effects and enhances directional sensitivity, particularly for high-energy neutrinos. The results highlight the potential of WCD arrays as complementary tools for neutrino astronomy, particularly in the context of multimessenger observations of transient astrophysical sources. The nearly continuous operation and wide field of view of these detectors further enhance their suitability for real-time monitoring and alert generation.

J. Alvarez-Muñiz

Italy

R. Colalillo

Portugal

R. Conceição

B. González

V. Grieco

F. Guarino

M. Pimenta

B. Tomé

M. Waqas

Enhancing neutrino reconstruction in water-Cherenkov air shower arrays using multi-photosensors

We show that nickel oxide, which is already a very promising target to look for sub-MeV dark matter scattering, can be employed to hunt axion dark matter, with masses in the meV range and couplings to electrons allowing them to potentially be QCD axions. We describe the interactions between axions and the collective excitations of nickel oxide in terms of an effective field theory, built solely out of symmetry arguments. The processes of conversion into one or two excitations provide, respectively, a narrow band and a broadband channel for the axion search, and the possibility of varying an external magnetic field up to a phase transition point allows one to cover a large portion of a yet unexplored parameter space, reaching axion masses down to few fractions of an meV. Our results underline nickel oxide as an ideal candidate for a multipurpose target for light dark matter searches.

Pier Giuseppe Catinari

Angelo Esposito

Shashin Pavaskar

Hunting axion dark matter with antiferromagnets: A case study with nickel oxide

We classify radiative corrections to spin polarization into three types: (i) spectral function, (ii) modified distribution function, and (iii) modified Kubo-Martin-Schwinger relation. The last two contributions modify the well-known free theory results. The first contribution is present with radiative correction only. We perform a detailed analysis on the first type for an energetic quark in a medium with hydrodynamic gradients, finding the radiative correction to spectral function leads to a polarized quasiparticle. The degeneracy of spin polarization induced by different hydrodynamic sources in free theory is lifted by radiative correction. We argue that the corrections of the last two types are parametrically suppressed with respect to the first type for the energetic quark we consider.

Shu Lin

Jiayuan Tian

Spin polarized quasiparticle in an off-equilibrium medium

In field theory, domain walls are constructed by embedding localized field configurations varying in one space dimension, such as the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>4</mn></msup></math> kink, in two or three space dimensions. At the classical level, the kink mass straightforwardly turns into the energy per unit length or area, known as the domain wall tension. The quantum contribution to the tension is more difficult to compute, because the quantum fluctuations about the domain wall in the additional coordinates must be included. We show that spectral methods, making use of scattering data for the interaction of quantum fluctuations with the domain wall background, are an efficient way to compute the leading quantum correction to the domain wall tension. In particular we demonstrate that within this approach it is straightforward to pass from one renormalization scheme to another.

N. Graham

South Africa

H. Weigel

Quantum contribution to domain wall tension from spectral methods

We search, for the first time, for an exotic molecular state with quantum numbers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mrow><mi>P</mi><mi>C</mi></mrow></msup><mo>=</mo><msup><mn>1</mn><mrow><mo>−</mo><mo>+</mo></mrow></msup></math>, called <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math>, via the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>γ</mi><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mrow><mi>s</mi><mn>1</mn></mrow><mo>−</mo></msubsup><mo stretchy="false">(</mo><mn>2536</mn><mo stretchy="false">)</mo><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></math> using data samples corresponding to a luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.8</mn><mtext> </mtext><mtext> </mtext><mrow><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></mrow></math> across center-of-mass energies from 4.612 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>4.951</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, collected with the BESIII detector operating at the BEPCII Collider. No statistically significant signal is observed. The upper limits on the product of cross section and branching fraction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi><mo stretchy="false">(</mo><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>γ</mi><mi>X</mi></mrow><mo stretchy="false">)</mo><mo>·</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>X</mi><mo stretchy="false">→</mo><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mrow><mi>s</mi><mn>1</mn></mrow><mo>−</mo></msubsup><mo stretchy="false">(</mo><mn>2536</mn><mo stretchy="false">)</mo><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo><mo stretchy="false">)</mo></math> at 90% confidence level are reported for each energy point, assuming the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> mass to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>4.503</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math> and the width 25, 50, 75, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>100</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>, respectively.

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

A. Amoroso

Y. Bai

JINR

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

R.A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

South Korea

S.K. Choi

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

Y.T. Feng

M. Fritsch

C.D. Fu

J.L. Fu

Y.W. Fu

H. Gao

X.B. Gao

Search for a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mn>1</mn><mrow><mo>−</mo><mo>+</mo></mrow></msup></math> molecular state via <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>γ</mi><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mrow><mi>s</mi><mn>1</mn></mrow><mo>−</mo></msubsup><mo stretchy="false">(</mo><mn>2536</mn><mo stretchy="false">)</mo><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></math>

The gravitational collapse of a star can lead to the formation of a regular black hole. However, a key factor in this process is the transition of ordinary baryonic matter into a substance that forms the de Sitter core. However, the formation of de Sitter core during gravitational collapse remains an open question, particularly since ordinary baryonic matter does not naturally transition into the exotic matter required to form a de Sitter core. In this paper, we investigate the gravitational collapse of baryonic matter and its potential to form well-known regular black hole solutions, such as those proposed by Dymnikova and Hayward. We model the collapse process as a transition of baryonic matter into a new type of matter, accompanied by the release of energy in the form of electromagnetic radiation. Using a generalized dynamical framework, we derive the energy density of the emitted radiation as a function of both the properties of the initial baryonic matter and the resulting exotic matter. Our findings demonstrate that the gravitational collapse can lead to the formation of various types of regular black holes, providing insights into the physical mechanisms underlying their creation. The detectable radiation signature offers a potential observational test for distinguishing between different black hole models.

Azerbaijan

Vitalii Vertogradov

Gravitational collapse and formation of regular black holes: Dymnikova, Hayward, and beyond

This study examines the structure and stability of dark energy stars within the context of $$R^2$$ gravity, with the gravity model defined by $$f(R) = R + a R^2$$ (the Starobinsky model). Specifically, dark energy is a mysterious force that can prevent the gravitational collapse of compact objects to singularities. To characterize dark energy, we consider modified Chaplygin fluid as an equation of state (EoS) of matter and study its mass-radius relation for different model parameters. By numerically solving the modified Tolman–Oppenheimer–Volkoff (TOV) equations, our primary objective is to examine the influence of variations in the $$R^2$$ gravity parameter $\textit{a}$ on the energy density, pressure, mass-radius and mass-central density relationships of dark energy stars. Our findings reveal that the variation of $\textit{a}$ does not significantly impact on the $$(M-R)$$ relations but comfortably exceeds the 2 $$M_{\odot }$$ limit. Additionally, we examine the dynamical stability of these stars by evaluating the static stability criterion, adiabatic index, and sound speed. Finally, we compare our results with various astrophysical observational data and discuss future observations that could validate the predictions of our model.

Ayan Banerjee

Saudi Arabia

Safiqul Islam

Uzbekistan

Javlon Rayimbaev

Inomjon Ibragimov

Sokhibjan Muminov

Ikram Davletov

Comprehensive analysis of dark energy stars in $\textit{R}$-squared gravity

Australia

J. Altmann

H. Li

L. Scyboz

P. Skands

Sudakov evolution without unitarity