We perform a comprehensive observational test of a canonical quintessence model driven by an exponential potential, motivated by its emergence in higher-dimensional theories, string-inspired scenarios, and modified gravity. Using a Markov Chain Monte Carlo framework, we constrain the model with the latest high-precision observational datasets–Cosmic Chronometers, Baryon Acoustic Oscillation, Pantheon $$^+$$ , and DES-SN5YR Type Ia Supernovae. The combined data significantly tighten the parameter bounds on $$(H_0, \Omega _{m_0}, \eta _0, \gamma )$$ and yield predictions for the Hubble parameter $\textit{H}$($\textit{z}$), the distance modulus $$\mu (z)$$ , and the scaled comoving angular diameter distance that remain in excellent agreement with observations and closely follow the $$\Lambda $$ CDM baseline. In addition, an information-theoretic model comparison based on the Akaike Information Criterion shows that the exponential quintessence model remains statistically comparable with the $$\Lambda $$ CDM scenario, despite the penalty associated with its additional parameters. The model naturally reproduces the transition from matter domination to late-time acceleration, maintains total equation of state $$\omega _{\textrm{tot}} > -1$$ as expected for canonical scalar fields, and provides an age of the universe consistent with $\textit{Planck}$ 2018. The Statefinder diagnostics show trajectories approaching the $$\Lambda $$ CDM fixed point, while allowing small observable departures. Energy condition analysis confirms physical viability, with only the Strong Energy Condition violated at late times, as required for acceleration. Overall, our results show that quintessence with an exponential potential provides a stable, observationally consistent alternative to $$\Lambda $$ CDM. Using the latest high-precision datasets, we obtain some of the most stringent constraints on this exponential-potential quintessence model, reaffirming its viability as a compelling dynamical explanation for dark energy.

India

Sanjeeda Sultana

Surajit Chattopadhyay

Cosmological dynamics of exponential quintessence constrained by BAO, cosmic chronometers, and DES-SN5YR/Pantheon $$^+$$ data

We study correlation numbers in Virasoro minimal string [ ]. Using analytic properties of correlation functions in spacelike and timelike Liouville theories, we verify exact expressions for correlation numbers for the four punctured sphere and the once punctured torus conjectured in [ (2024) 057 ].

Russia

Dmitry Khromov

Alexey Litvinov

On correlation numbers $\textit{V}$ 0$\textit{,}$4 and $\textit{V}$ 1$\textit{,}$1 in Virasoro minimal string theory

Within the framework of nonrelativistic QCD (NRQCD) factorization, and based on the Collins-Soper operator definition of fragmentation functions, we present a systematic calculation of the fragmentation functions for a heavy quark fragmenting into color-singlet $\textit{P}$-wave quarkonium states. After reproducing and confirming the known leading-order results, we further compute the relativistic corrections up to order $$ \mathcal{O}\left({v}^2\right) $$ . Our analysis applies both to quarkonium systems composed of heavy quarks with the same flavor and to $\textit{B}$ -type mesons formed by heavy quarks of different flavors. Numerical results show that, for all color-singlet $\textit{P}$-wave channels, the $$ \mathcal{O}\left({v}^2\right) $$ relativistic corrections give sizable negative contributions over most of the momentum-fraction $\textit{z}$ region. We further compute inclusive cross sections for $\textit{P}$-wave quarkonium plus charmed hadrons in $\textit{e}$ $\textit{e}$ annihilation via the single photon process up to $$ \mathcal{O}\left({v}^2\right) $$ by applying our obtained fragmentation functions, and the resulting predictions are consistent with the full fixed-order results in the high-energy region.

China

Sai Cui

Sheng-Juan Jiang

Guang-Zhi Xu

Kui-Yong Liu

Order-$\textit{v}$ 2 relativistic corrections to heavy-quark fragmentation into $\textit{P}$-wave quarkonium states

The Giant Dipole Resonance (GDR) in 51V has been a long-term conflicting interpretation, with existing photoneutron cross section data suggesting either a single peak or a pronounced splitting, leading to opposite conclusions on nuclear deformation. A new measurement of the 51V( <italic>&#947;</italic>,1n) cross section, performed at the Shanghai Laser Electron Gamma Source (SLEGS) facility, employs a refined monochromatic cross section extraction method. By integrating Polynomial Regression and Support Vector Regression (SVR) for robust interpolation and extrapolation, the new extracted monoenergetic cross sections exhibit a single, broad peak with no evidence of GDR splitting. Re-analysis of the reported splitting shows that any deformation extracted from such a structure would be relatively weaker than those of neighboring nuclei, providing a support for a spherical or near-spherical shape of 51V. Furthermore, we found that deliberately overfitting the data using an SVR model reproduces multi-peak structures similar to those reported in historical datasets, implying that the previously claimed splitting might originated from analysis artifacts rather than physical phenomena.

Zi-Rui Hao

Gong-Tao Fan

Chen Chen

Qian-Kun Sun

Hong-Wei Wang

Yi-Fei Niu

Hang-Hua Xu

Long-Xiang Liu

Yue Zhang

Yu-Xuan Yang

Kai-Jie Chen

Zhi-Cai Li

Pu Jiao

Meng-Die Zhou

Shan Ye

Zhen-Wei Wang

Xiang-Fei Wang

Meng-Ke Xu

Yu-Long Shen

Chang Yang

Jia-Wen Ding

New measurement of 51V( <italic>&#947;</italic>,1n) cross section through the refined monochromatic cross section extraction method

We investigate thermal photon production in the quark-gluon plasma (QGP) under strong magnetic fields using a magnetohydrodynamic (MHD) framework. We employ relativistic ideal fluid dynamics under the non-resistive approximation by adopting the Bjorken flow model with power-law decaying magnetic fields $ \mathbf{B}(\tau) = \mathbf{B}_0 (\tau_0/\tau)^a $ , span> $\textit{a}$ controls the decay rate, $ B_0 = \sqrt{\sigma} T_0^2 $ , and $\textit{σ}$ characterizes the initial field strength. The resulting QGP temperature evolution exhibits distinct $\textit{a}$- and $\textit{σ}$-dependent behaviors. Thermal photon production rates are calculated for three dominant processes: Compton scattering with $ q\bar{q} $ annihilation (C+A), bremsstrahlung (Brems), and $ q\bar{q} $ annihilation with additional scattering (A+S). These rates are integrated over the space-time volume to obtain the photon transverse momentum $ (p_T) $ spectrum. Our results demonstrate that increasing $\textit{a}$ enhances photon yields across all $ p_T $ , with $ a \to \infty $ (super-fast decay) providing an upper bound. For $ a = 2/3 $ , a larger $\textit{σ}$ suppresses yields through accelerated cooling, whereas for $ a \to \infty $ , a larger $\textit{σ}$ enhances yields via prolonged thermal emission. Low- $ p_T $ photons receive significant contributions from all QGP evolution stages, while high- $ p_T $ photons originate predominantly from early times. The central rapidity region $ (y=0) $ dominates the total yield. This work extends the photon yield studies to the MHD regime under strong magnetic fields, clarifying the magnetic field effects on QGP electromagnetic signatures and establishing foundations for future investigations of magnetization and dissipative phenomena.

Jie Xiong

Xiang Fan

Jing Jing

Weishan Yang

Duan She

Ze-Fang Jiang

Thermal photon emission from quark-gluon plasma: 1+1D magnetohydrodynamics results * Supported by the National Natural Science Foundation of China (NSFC) (12305138). Duan She's research is funded by the Startup Research Fund of Henan Academy of Sciences (231820058) and the 2024 Henan Province International Science and Technology Cooperation Projects (242102521068)

We consider the V-A Fermi interaction and apply an earlier developed method for summing up the leading asymptotics for scattering amplitudes in non-renormalizable theories. We consider the amplitude of fermion-antifermion scattering and derive the corresponding RG equation that sums the leading logarithmic contributions just like in renormalizable models. Numerical solution of this equation in the asymptotic regime <italic>s</italic>&#8239;&#8764;&#8239; <italic>t</italic>&#8239;&#8764;&#8239; <italic>u</italic>&#8239;&#8764;&#8239; <italic>E</italic> 2&#8239;&#8594;&#8239;&#8734; leads to amplitude logarithmically decreasing with energy, thus restoring the unitarity violated at the tree level.

Arthur Borlakov

Dmitry Kazakov

Asymptotic freedom of V-A Fermi interaction

In light of ongoing issues with the first-row unitarity test of the Cabibbo-Kobayashi-Maskawa matrix, we showcase a global fit to measurements of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">→</mo><mo>ℓ</mo><mi>ν</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">→</mo><mi>π</mi><mo>ℓ</mo><mi>ν</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mo stretchy="false">→</mo><mi>K</mi><mi>ν</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mo stretchy="false">→</mo><mi>K</mi><mi>π</mi><mi>ν</mi></math> decays for the first time. Fitting the semileptonic and three-body <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> decay data simultaneously becomes computationally feasible because we employ a simple form factor parametrization for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi>π</mi></math> form factor that manifestly connects the semileptonic and pair-production regions. We find good agreement with the data and use our analyses to infer <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo stretchy="false">|</mo></math> and the parameters for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi>π</mi></math> form factors. Our result for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo stretchy="false">|</mo></math> sits close to the results extracted from exclusive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mrow><mo>ℓ</mo><mn>2</mn></mrow></msub></math> and somewhat above the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mrow><mo>ℓ</mo><mn>3</mn></mrow></msub></math> decay and inclusive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> decay result. Moreover, our results for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">→</mo><mi>π</mi></math> vector form factor at zero momentum transfer are compatible with lattice QCD determinations, despite not using lattice QCD inputs for this quantity in our fit of the hadronic matrix elements. We are further able to determine some of the pole parameters of the individual scalar and vector <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi>π</mi></math> resonances with masses below the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> mass. We caution that our results account only for short-distance electromagnetic corrections but not long-distance contributions; this is due to the lack of a consistent description of long-distance corrections to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mi>π</mi></math> matrix elements both above and below threshold for an arbitrary model of the form factors.

United Kingdom

Matthew Kirk

Danny van Dyk

Global determination of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">|</mo><msub><mrow><mi>V</mi></mrow><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo stretchy="false">|</mo></mrow></math>

Within the framework of nonrelativistic quantum chromodynamics (NRQCD) factorization, we compute the $$ \mathcal{O}\left({v}^4\right) $$ relativistic corrections to the fragmentation of a heavy quark into the color-singlet $$ {}^1{S}_0^{\left[1\right]} $$ and $$ {}^3{S}_1^{\left[1\right]} $$ quarkonium states. Using the Collins-Soper definition of the fragmentation function, we reproduce the known $$ \mathcal{O}\left({v}^2\right) $$ results. We find that the $$ \mathcal{O}\left({v}^4\right) $$ correction gives a positive contribution relative to the leading order result over a wide range of the light-cone momentum fraction $\textit{z}$, while its magnitude remains much smaller than that of the $$ \mathcal{O}\left({v}^2\right) $$ correction. This behavior indicates a good convergence of the NRQCD relativistic expansion in this process. We further extend the calculation to the fragmentation functions in the unequal-mass case at $$ \mathcal{O}\left({v}^4\right) $$ and obtain the corresponding analytical expressions.

Yi-Jie Li

Order-$\textit{v}$ 4 corrections to heavy quark fragmentation to $\textit{S}$-wave heavy quarkonium

This paper presents a search for new physics through the process where a massive particle, X, decays into a Higgs boson and a second particle, Y. The Higgs boson subsequently decays into a bottom quark–antiquark pair, which is reconstructed as a single large-radius jet. The decay products of Yare also assumed to produce a single large-radius jet. The identification of the Yparticle is enhanced by computing the anomaly score of its candidate jet using an autoencoder, which measures deviations from typical quark- or gluon-induced jets. This allows a simultaneous search for multiple Ydecay scenarios within a single analysis. In the main benchmark process, Yis a scalar particle that decays into a Wboson pair. Two other scalar Ydecay processes are also considered as benchmarks: decays to a light quark–antiquark pair, and decays to a top quark–antiquark pair. A fourth benchmark process considers Yas a hadronically decaying top quark, arising from the decay of a vector-like quark into a top quark and a Higgs boson. Data recorded by the CMS experiment at a center-of-mass energy of 13 $$\,\text {Te}\hspace{-.08em}\text {V}$$ in 2016–2018, corresponding to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ , are analyzed. The search covers Xmasses between 1.4 and 3.0 $$\,\text {Te}\hspace{-.08em}\text {V}$$ and Ymasses between 90 and 400 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ , with all simulated signals produced in the narrow-width approximation. No significant excess above the standard model background expectation is observed. The most stringent upper limits to date are placed on benchmark signal cross sections for various masses of X and Y particles

Armenia

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

M. Dragicevic

C. Giordano

P. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

M. Matthewman

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Shooshtari

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

D. Ocampo Henao

T. Laer

P. Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

Y. Hong

P. Kashko

S. Lowette

I. Makarenko

D. Müller

J. Song

S. Tavernier

M. Tytgat

G. Onsem

S. Putte

D. Vannerom

B. Bilin

B. Clerbaux

A. Das

I. Bruyn

G. Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F. Khan

A. Malara

M. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. Coen

D. Dobur

G. Gokbulut

J. Knolle

D. Marckx

K. Skovpen

N. Bossche

J. Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. Favereau De Jeneret

C. Delaere

A. Giammanco

A. Guzel

V. Lemaitre

J. Lidrych

P. Malek

P. Mastrapasqua

S. Turkcapar

Brazil

G. Alves

M. Barroso Ferreira Filho

E. Coelho

C. Hensel

T. Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E. Tonelli Manganote

A. Vilela Pereira

W. Aldá Júnior

H. Brandao Malbouisson

W. Carvalho

Search for resonances decaying to an anomalous jet and a Higgs boson in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$

A sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>365</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></mrow><mo stretchy="false">→</mo><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>4</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mrow><mi>B</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover></mrow></math> data collected by the Belle II experiment is used to measure the partial branching fractions of charmless semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> meson decays and determine the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub></math>. Events containing a signal electron or muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo></math> and a fully reconstructed hadronic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> decay that constrains the signal kinematics are selected, while the rest of the event defines the hadronic system <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>X</mi><mi>u</mi></msub></math> associated with the signal. To discriminate the signal from the 50-times larger background originating from CKM-favored semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> decays, a template fit is performed in both signal and control regions after applying an optimized selection. The partial branching fraction measured for lepton energies greater than 1 GeV in the signal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> meson rest frame is <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Δ</mi><mi mathvariant="script">B</mi></mrow><mo stretchy="false">(</mo><mrow><mi>B</mi><mo stretchy="false">→</mo><msub><mi>X</mi><mi>u</mi></msub><mo>ℓ</mo><mi>ν</mi></mrow><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.54</mn><mo>±</mo><mn>0.08</mn><mrow><mo stretchy="false">(</mo><mi>stat</mi><mo stretchy="false">)</mo></mrow><mo>±</mo><mn>0.12</mn><mrow><mo stretchy="false">(</mo><mi>syst</mi><mo stretchy="false">)</mo></mrow><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math>. From this measurement, using the Gambino, Giordano, Ossola, Uraltsev theoretical framework, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo><mo>=</mo><mo stretchy="false">(</mo><mn>4.01</mn><mo>±</mo><mn>0.1</mn><msubsup><mn>9</mn><mrow><mo>−</mo><mn>0.08</mn></mrow><mrow><mo>+</mo><mn>0.07</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math> is determined, where the uncertainties are experimental and theoretical, respectively. This value is consistent with the world average obtained from previous inclusive measurements. Different theoretical predictions and partial branching fractions measured in other phase-space regions, defined by additional selections on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>X</mi><mi>u</mi></msub></math> and leptonic system masses, are also used to determine <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo></math>. This allows for a comparison of the resulting values across theoretical frameworks and phase-space regions.

M. Abumusabh

I. Adachi

K. Adamczyk

L. Aggarwal

H. Ahmed

Y. Ahn

H. Aihara

N. Akopov

S. Alghamdi

M. Alhakami

A. Aloisio

N. Althubiti

K. Amos

N. Anh Ky

C. Antonioli

D.M. Asner

H. Atmacan

T. Aushev

R. Ayad

V. Babu

H. Bae

N.K. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

M. Barrett

M. Bartl

J. Baudot

A. Beaubien

F. Becherer

J. Becker

J.V. Bennett

F.U. Bernlochner

V. Bertacchi

Measurement of inclusive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>X</mi><mi>u</mi></msub><mo>ℓ</mo><mi>ν</mi></math> partial branching fractions and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo></math> at Belle II