We investigated the effect of an isospin chemical potential ( $ \mu_{I} $ ) within the quark-meson model, which approximates quantum chromodynamics (QCD) by modeling low-energy phenomena such as chiral symmetry breaking and phase structure under varying conditions of temperature and chemical potential. Using the functional renormalization group (FRG) flow equations, we calculated the phase diagram in the chiral limit within the two-flavor quark-meson model in a finite $ \mu_{I} $ with $\textit{ρ}$ vector meson interactions. Fluctuation effects significantly decrease the critical chemical potential from the mean-field (MF) value $\mu_{I,{\rm MF}} \gt m_\rho$ to a lower value at which the $\textit{ρ}$ vector meson condensates alongside the chiral condensate once the isospin chemical potential exceeds the critical value $ \mu_{I}^{{\rm{crit}}} $ . This $\textit{ρ}$ condensation was investigated numerically for different meson coupling strengths. The $\textit{ρ}$ meson dominated region is delineated from other phases by a second-order phase transition at lower $ \mu_{I} $ and a first-order transition at slightly higher $ \mu_{I} $ .

China

Mohammed Osman

Defu Hou

Wentao Wang

United States

Hui Zhang

Functional renormalization group study of $\textit{ρ}$ meson condensate at a finite isospin chemical potential in the quark meson model * Supported in part by the National Key Research and Development Program of China (2022YFA1604900). This work is also partly supported by the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Hui Zhang acknowledges the financial support from the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008) and the National Natural Science Foundation of China (12047523, 12105107)

We study one-loop QCD corrections to the single transverse spin asymmetry in Drell-Yan process. The invariant mass of virtual photon and angular distributions of final lepton in Collins-Soper frame are measured. Especially, the transverse momentum of virtual photon is integrated out. Collinear twist-3 factorization formalism is adopted for the asymmetry. We use Feynman gauge in this work. To eliminate dependent twist-3 distribution functions, equation of motion for quark is used. The results satisfy both QED and QCD gauge invariance. It is confirmed that all divergences from virtual and real corrections can be removed consistently by collinear subtraction. Finite hard coefficients for the convolution of $$ \overline{q}(x) $$ and $\textit{T}$ ($\textit{x}$ , $\textit{x}$ ) are presented.

Guang-Peng Zhang

One-loop QCD corrections to SSA in unweighted Drell-Yan processes

We present a thorough investigation of the sources of uncertainties to the Drell-Yan production using state-of-the-art predictions for both neutral and charged current channels, focusing on the low invariant mass region. Differential predictions for the invariant mass spectrum are provided at N LO supplemented with exact charm and bottom quark mass effects calculated at $$ \mathcal{O}\left({\alpha}_s^2\right) $$ . The impact of PDF choices (including approximate N LO), scale variations, the variation of the strong coupling constant, and impact heavy quark mass effects on the distributions is studied in detail. We also comment on the correlation of high-energy astrophysical processes with the low-mass DY region.

Germany

Ekta Chaubey

Claude Duhr

Rhorry Gauld

Pooja Mukherjee

A comprehensive analysis of Drell-Yan production uncertainties and mass effects at moderate and low dilepton masses

In this paper, we present three types of teleparallel frames with cylindrical and spherical symmetry. The first example is the closed time-like curves (CTC) in cosmic strings in teleparallel $$T_{4}$$ gravity, which shows they are forbidden. Here, we show that in $$T_{4}$$ , in order to allow for CTC, we are also led to a lower bound on the angular momentum of the cosmic string. This result matches the interior $$T_{4}$$ solution to a General Relativity (GR) vacuum solution. One of the main differences between the present report and the one by Soleng is that, here, the interior symmetric solution does not have polarized spins but only Cartan torsion in the spirit of teleparallelism. Torsion flux is computed to show that a cylindrical central singularity corresponds to a $$(2+1)$$ -spacetime rotating point particle in $$T_{4}$$ . Therefore, the possibility of building time machines seems to be strongly constrained compared with Einstein–Cartan (EC) gravity. We present a spherically symmetric black hole with an open string along a particular direction of the black hole (BH). In this case, it is shown that when the teleparallel frame used is the one where all spin coefficients vanish, a torsion flux cutoff appears along one of the directions. In the stringy BH case, choosing a restricted teleparallel frame, a torsion-axion-like hair appears in the form of an axion scalar. A Kerr Nieh–Yan (NY) invariant black hole is obtained. Coley et al. previously obtained BH solutions in teleparallel spacetime, which present horizon singularities but not torsion singularities.

Brazil

Croatia

L. Garcia de Andrade

Strings in Gödel CTC and in hairy axionic black holes with Kerr Nieh–Yan charges in teleparallelism

We present results from a global fit of Standard Model parameters and dimension-6 SMEFT Wilson coefficients that includes electroweak, Drell-Yan, Higgs-boson, top-quark, and flavour observables. Fits obtained by floating individual coefficients are also discussed. The leading-order scale dependence of the SMEFT Wilson coefficients is consistently included in the evolution from the UV scale to the electroweak scale and the low-energy scale of flavour observables. In defining the SMEFT set of active operators we consider both the U(3) and the U(2) flavour symmetric limits. All fits are obtained within the HEPfit framework and are based on the most recent experimental results and state-of-the-art theoretical predictions for all the observables considered.

Spain

Jorge Blas

Angelica Goncalves

United Kingdom

Víctor Miralles

Laura Reina

Italy

Luca Silvestrini

Mauro Valli

Constraining new physics effective interactions via a global fit of electroweak, Drell-Yan, Higgs, top, and flavour observables

Higgs self-coupling is crucial to understand the structure of the scalar potential and the mechanism of electroweak symmetry breaking. In this study, we utilize a deep neural network based on a particle Transformer model that relies on an attention mechanism to comprehensively analyze the measured trilinear Higgs self-coupling through Higgs pair production with subsequent decay into four $\textit{b}$-quarks ( $ HH\to b\bar{b}b\bar{b} $ ) at the LHC. The model processes the full event-level information as input and bypasses explicit jet pairing. It also serves as an event classifier. At HL-LHC, our approach constrains $ \kappa_\lambda $ to $ (-0.25,\,5.41) $ at 68% CL, and thus achieved an improvement of ~44% in precision over conventional cut-based analyses. The results of a comparison against alternative machine learning architectures demonstrate the outstanding performance of the Transformer-based model owing to its ability to capture correlations in high-dimensional collision data with the help of the attention mechanism. These findings highlight the potential of attention-based networks and end-to-end event classifiers in collider phenomenology.

Yongcheng Wu

Liang Xiao

Yan Zhang

Deep learning to improve the sensitivity of Higgs pair searches in the 4$\textit{b}$ channel at the LHC * Supported by the National Natural Science Foundation of China (NNSFC) (12305112)

Using $\textit{e}$ $\textit{e}$ collision data corresponding to an integrated luminosity of 22.7 fb , collected at center-of-mass energies between 3.7 and 4.7 GeV with the BESIII detector at the BEPCII storage ring, we measure the energy-dependent Born cross sections of $$ {e}^{+}{e}^{-}\to {\varOmega}^{-}{\overline{\varOmega}}^{+} $$ and the effective form factors of the Ω baryon. The analysis employs a single baryon tagging method, and the results are consistent with theoretical predictions, providing critical constraints on the electromagnetic structure of the Ω hyperon. No significant signal of charmonium or charmonium-like states decaying to $$ {\varOmega}^{-}{\overline{\varOmega}}^{+} $$ is observed in the investigated energy range.

M. Ablikim

Russia

M. Achasov

Sweden

P. Adlarson

O. Afedulidis

X. Ai

R. Aliberti

A. Amoroso

Q. An

Y. Bai

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. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G. Cao

N. Cao

Türkiye

S. Cetin

J. Chang

W. Chang

G. Che

G. Chelkov

C. Chen

Chao Chen

G. Chen

H. Chen

M. Chen

S. Chen

T. Chen

X. Chen

Y. Chen

Z. Chen

South Korea

S. Choi

X. Chu

G. Cibinetto

F. Cossio

J. Cui

H. Dai

J. Dai

A. Dbeyssi

R. Boer

D. Dedovich

C. Deng

Z. Deng

A. Denig

I. Denysenko

M. Destefanis

F. Mori

B. Ding

X. Ding

Y. Ding

J. Dong

L. Dong

M. Dong

X. Dong

M. Du

S. Du

Z. Duan

P. Egorov

Y. Fan

J. Fang

S. Fang

W. Fang

Y. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C. Feng

J. Feng

Y. Feng

K. Fischer

M. Fritsch

C. Fu

J. Fu

Y. Fu

H. Gao

Y. Gao

Measurement of Born cross sections and effective form factors of $$ {e}^{+}{e}^{-}\to {\varOmega}^{-}{\overline{\varOmega}}^{+} $$ from $$ \sqrt{s}=3.7 $$ to 4$\textit{.}$7 GeV

We consider the transverse-momentum ($\textit{q}$ ) distribution of Drell-Yan lepton pairs produced with invariant masses ($\textit{M}$) from low values up to the $\textit{Z}$-boson peak (4 $\textit{≤ M ≤}$ 116 GeV). We present perturbative predictions obtained by consistently combining the resummation of logarithmically enhanced QCD corrections at small $\textit{q}$ ($\textit{q}$ ≪ $\textit{M}$) up to next-to-next-to-next-to-next-to-leading logarithmic accuracy with the available fixed-order calculations at next-to-next-to-leading order (i.e. $$\mathcal{O}({\alpha }_{S}^{3})$$ ) valid at large $\textit{q}$ . For very low $\textit{q}$ ($\textit{q}$ ~ Λ ), non-perturbative (NP) QCD effects become dominant and have been included through a NP form factor with a small number of free-parameters. We compare our results with multiple experimental datasets from hadron colliders, finding excellent agreement between theory and data. By fitting the NP parameters, we achieve a precise extraction of the NP form factor and the so-called Collins-Soper kernel.

Switzerland

Stefano Camarda

Giancarlo Ferrera

Lorenzo Rossi

Drell-Yan lepton pair production at low invariant masses: transverse-momentum resummation and non-perturbative effects in QCD

<p>By analyzing a data sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> collisions with center-of-mass energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>3.773</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>7.9</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> collected with the BESIII detector operating at the BEPCII collider, we study semileptonic decays of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mn>0</mn><mo stretchy="false">(</mo><mo>+</mo><mo stretchy="false">)</mo></mrow></msup></math> mesons into the axial-vector meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1235</mn><mo stretchy="false">)</mo></math> via the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ω</mi><mi>π</mi></mrow></math>. The decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math> is observed with a significance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.2</mn><mi>σ</mi></mrow></math> after considering systematic uncertainty, while evidence for the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math> is obtained with a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.1</mn><mi>σ</mi></mrow></math> significance. The product branching fractions are determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>×</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>0.72</mn><mo>±</mo><mn>0.1</mn><msubsup><mrow><mn>8</mn></mrow><mrow><mo>−</mo><mn>0.08</mn></mrow><mrow><mo>+</mo><mn>0.06</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>×</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">]</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>1.16</mn><mo>±</mo><mn>0.44</mn><mo>±</mo><mn>0.16</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>, where the first uncertainties are statistical and the second systematic. The ratio of their partial decay widths is determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">{</mo><mi mathvariant="normal">Γ</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo stretchy="false">−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>/</mo><mn>2</mn><mi mathvariant="normal">Γ</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo stretchy="false">}</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mn>0.78</mn><mo>±</mo><mn>0.1</mn><msubsup><mrow><mn>9</mn></mrow><mrow><mo>−</mo><mn>0.05</mn></mrow><mrow><mo>+</mo><mn>0.04</mn></mrow></msubsup></mrow></math>, which is consistent with unity, predicted by isospin invariance, within uncertainties.</p>

M.N. Achasov

X.C. Ai

JINR

R.A. Briere

G.F. Cao

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

C.H. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

Z.Y. Chen

S.K. Choi

J.J. Cui

H.L. Dai

J.P. Dai

R.E. de Boer

C.Q. Deng

Z.Y. Deng

F. De Mori

X.X. Ding

L.Y. Dong

M.Y. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

Y.H. Fan

S.S. Fang

W.X. Fang

Y.Q. Fang

C.Q. Feng

J.H. Feng

Y.T. Feng

C.D. Fu

J.L. Fu

Y.W. Fu

Observation of the Singly Cabibbo Suppressed Decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msub><mi>b</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mo stretchy="false">)</mo><mo>−</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>e</mi></msub></math> and Evidence for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math>

In this study, we investigate the mass spectrum of the $$\Omega \bar{\Omega }$$ states with quantum numbers $$J^{PC}=0^{-+}$$ , $$1^{--}$$ , $$0^{++}$$ , and $$1^{++}$$ within the framework of QCD sum rules. Employing suitably constructed interpolating currents, the analyses are carried out with the operator product expansion (OPE) including condensate contributions up to dimension 12. Our results indicate the existence of four possible baryonium states with masses $$m_{0^{-+}}=(3.22\pm 0.07)$$ GeV, $$m_{1^{--}}=(3.28\pm 0.08)$$ GeV, $$m_{0^{++}}=(3.46\pm 0.09)$$ GeV, and $$m_{1^{++}}=(3.54\pm 0.11)$$ GeV. For the $$0^{-+}$$ and $$1^{--}$$ states, the predicted masses lie below the corresponding dibaryon thresholds, suggesting possible bound-state configurations. In contrast, the $$0^{++}$$ and $$1^{++}$$ states are found above the respective thresholds, implying resonance-like behavior. Potential decay channels for these baryonium candidates are discussed, with emphasis on those accessible to current experimental facilities such as BESIII, Belle II, and LHCb.

Bing-Dong Wan

Jun-Hao Zhang

Mass spectrum of the $$\Omega \bar{\Omega }$$ states