Using BRST cohomology properties in pure spinor superspace and identities for OPE brackets of non-free fields, we obtain a new compact nested-bracket representation of massive tree-level three-point open-string amplitudes in which Möbius invariance is manifest. Explicit superspace calculations for amplitudes with level-one massive states confirm this finding, and we derive new BRST recurrence relations among three-point numerators to extend the result to arbitrary mass levels. This provides a manifestly Möbius-invariant expression for massive three-point amplitudes in the pure spinor formalism.

United Kingdom

Chen Huang

Carlos Mafra

China

Sweden

Yi-Xiao Tao

Manifest Möbius invariance of massive tree-level three-point amplitudes in pure spinor superspace

We study Wilson loops on the Coulomb branch of $\textit{N}$ = 4 super-Yang-Mills theory, by solving for minimal surface that connect the contour on the boundary with the D3-brane in the bulk. The circular loop undergoes the Gross-Ooguri transition as a function of the radius and angular separation, and we fully map its phase diagram. As a byproduct we find evidence that the expectation value of the straight line is tree-level exact.

Belgium

Jarne Moens

Denmark

Konstantin Zarembo

Wilson loops on the Coulomb branch of N=4 super-Yang-Mills

The ratio between the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mi>B</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></mrow><msup><mi>τ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>τ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mi>B</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></mrow><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub></math> branching fractions is measured using a data sample of proton-proton collisions collected by CMS at a center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math> in the years 2016–2018 and corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> meson is identified through its <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><mo stretchy="false">→</mo><mrow><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></mrow></math> decay and the tau lepton is reconstructed in the hadronic three-prong final state. The measured ratio of branching fractions in this tau decay mode, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="script">R</mi><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><mi>had</mi></msubsup><mo>=</mo><mn>1.0</mn><msubsup><mn>4</mn><mrow><mo>−</mo><mn>0.44</mn></mrow><mrow><mo>+</mo><mn>0.50</mn></mrow></msubsup></math>, is combined with the previous analysis based on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>τ</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub><msub><mrow><mover accent="true"><mrow><mi>ν</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mi>τ</mi></mrow></msub></mrow></math> leptonic decay channel, leading to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">R</mi><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></msub><mo>=</mo><mrow><mn>0.49</mn><mo>±</mo><mn>0.26</mn></mrow></math>. As this result is consistent with the standard model prediction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.258</mn><mo>±</mo><mn>0.004</mn></math>, no evidence of lepton flavor universality violation is found.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

K. Damanakis

M. Dragicevic

C. Giordano

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Shooshtari

M. Sonawane

W. Waltenberger

C.E. Wulz

T. Janssen

H. Kwon

T. Van Laer

P. Van Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

J. Song

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Bilin

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F.A. Khan

A. Malara

M.A. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. De Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Van Den Bossche

J. van der Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. De Favereau De Jeneret

C. Delaere

A. Giammanco

A.O. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

S. Turkcapar

Brazil

G.A. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E.J. Tonelli Manganote

A. Vilela Pereira

W.L. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

Measurement of the ratio of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>τ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>τ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub></math> branching fractions using three-prong <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton decays

A general spin-resolved momentum distribution of electron-positron pairs produced in strong external fields is derived by combining the covariant spin projection operator and the Dirac-Heisenberg-Wigner formalism. The result shows that the spin-resolved and helicity-resolved momentum distributions given in previous literature are actually two special cases of it. By numerically studying pair production in a spatially homogeneous circularly polarized electric field with its rotation axis along the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> axis, it is found that for any spin-direction unit vector, when the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> component of the unit vector vanishes, the number densities of produced spin-up and spin-down particles are equal, while their momentum distributions have some asymmetry. When the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> component of the unit vector is nonzero, there is a difference of 1–3 orders of magnitude in the number densities of spin-up and spin-down particles induced by angular momentum transfer in multiphoton absorption. Moreover, as the electric field strength increases or the field frequency decreases, the asymmetry between the spin-up and spin-down particle number densities decreases rapidly. These results offer an approach to study general spin states in vacuum pair production and enhance our understanding of angular momentum transfer from fields to matter in extreme environments.

R.Z. Jiang

Z.L. Li

Y.J. Li

Study of spin states in vacuum pair production in the Dirac-Heisenberg-Wigner formalism

We show that the leading nonanalytic terms in the small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>t</mi></mrow></math> expansion of the energy-momentum tensor form factors of an electrically charged particle in QED can be correctly derived in a classical model of the electron by Białynicki-Birula. Based on the lucidity of the employed exactly solvable model, we comment also on the recently proposed concept of a regularized proton <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math>-term.

United States

Grace Gardella

Mira Varma

Peter Schweitzer

Energy-momentum tensor in a classical model of the electron

The femtoscopic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mi>s</mi><mo>−</mo></msubsup></math> correlations are investigated to predict the signature of the not-yet-established <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>3960</mn><mo stretchy="false">)</mo></math> state reported by the LHCb Collaboration in three scenarios: resonant, virtual, or bound. In the last two scenarios, it might also be identified as the state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>3930</mn><mo stretchy="false">)</mo></math>. The formalism employed to generate this structure dynamically is based on the Bethe-Salpeter equation with a general <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave potential. We investigate how the relevant properties and observables characterizing this state—such as the pole position, scattering length, and effective range—might be affected by variations in the model parameters. The amplitudes encoding the distinct interpretations of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>3960</mn><mo stretchy="false">)</mo></math> state are then used as input to calculate the femtoscopic correlation function of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mi>s</mi><mo>−</mo></msubsup></math> pair, which is analyzed and discussed.

Hao-Nan Liu

Zhi-Wei Liu

Luciano Abreu

Li-Sheng Geng

Traces of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>X</mi><mo stretchy="false">(</mo><mn>3960</mn><mo stretchy="false">)</mo></mrow></math> state in the femtoscopic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><msubsup><mi>D</mi><mi>s</mi><mo>−</mo></msubsup></math> correlations

We study the evolution of neutrinos electroweakly interacting with a rotating matter. The description of neutrinos is based on the Dirac equation in the corotating noninertial frame where matter is at rest. We find the solution of this Dirac equation, where the matter angular velocity is accounted for exactly, for massless neutrinos. In case of massive particles, this solution is obtained for a slowly rotating matter. Our findings are compared with previous research. We consider two applications of our results. First, we compute the electroweak contribution to the vector current of neutrinos along the rotation axis, which is analogous to the chiral vortical effect. This current is shown to be nonzero for both massless and massive particles. Then, we take into account the nonzero mixing between different mass eigenstates. It allows us to study neutrino flavor oscillations in rotating matter and account for noninertial effects. We derive the transition probability which reveals the resonance. These findings generalize the description of neutrino oscillations in a nonmoving matter. Some astrophysical applications are briefly discussed.

Russia

Alexander Breev

Maxim Dvornikov

Relativistic quantum mechanics of massive neutrinos in a rotating frame

We constrain the Hu–Sawicki and Starobinsky $\textit{f}$($\textit{R}$) gravity models utilizing current electromagnetic (PantheonPlus + cosmic chronometers [PP+CC], Planck, and DESI2) datasets and simulate standard siren (SS) catalogs based on the resulting best-fit parameters. We demonstrate that the simulated SS data provide complementary sensitivity to the modified gravitational wave propagation friction term, thereby enhancing the discriminating power between $\textit{f}$($\textit{R}$) gravity and the $$\varLambda $$ CDM model. However, we note that standard sirens do not offer a viable resolution to the Hubble tension in this analysis, as the inferred constraints are predominantly driven by the fiducial cosmologies adopted in the simulations. Regarding the specific models, we find that for the Hu–Sawicki scenario, several data combinations favor $$F_{RR0}<0$$ , implying potential theoretical instabilities. And, for the Starobinsky model, while electromagnetic-only constraints are nearly symmetric between the two parameter branches ( $$b<0$$ and $$b>0$$ ), the inclusion of SS constraints introduces mild asymmetries, revealing the sensitivity of SS observables to the curvature dependence of the theory. Future truly independent standard siren observations would be crucial for a definitive assessment of $\textit{f}$($\textit{R}$) gravity as an alternative to $$\varLambda $$ CDM.

Yi Zhang

Xuanjun Niu

Xianfu Su

Dong-Ze He

The standard siren tests of viable $\textit{f}$($\textit{R}$) cosmologies

In this work, the potential parameters of the independent quark model are systematically reduced using previously determined inputs from a broad range of baryons. The reduced-parameter formulation, developed within the relativistic Dirac formalism and employing a Martin-like potential, is then applied to the spectroscopy of the singly heavy baryons $$\Xi _c^0$$ and $$\Xi _b^-$$ in anti-triplet( $$\bar{\textbf{3}}$$ ) and sextet( $$\textbf{6}$$ ) representations. This enables an explicit verification of the linear relation obtained between the potential parameters. Radially and orbitally excited state masses are calculated accordingly, and the resulting Regge trajectories are used to assign spin-parity of experimentally observed states. The observed states $$\Xi _c^0(2882)$$ , $$\Xi _c^0(2923)$$ , and $$\Xi _c^0(2970)$$ are interpreted as $$J^P = \tfrac{3}{2}^-$$ states, where $$\Xi _c^0(2882)$$ is assigned to the anti-triplet ( $$\bar{\textbf{3}}$$ ) configuration, while $$\Xi _c^0(2923)$$ and $$\Xi _c^0(2970)$$ are identified as sextet ( $$\textbf{6}$$ ) states. In the bottom sector, the $$\Xi _b^-(6227)$$ state is interpreted either as a $$\bar{\textbf{3}}$$ baryon with $$J^P = \tfrac{5}{2}^+$$ or as a $$\textbf{6}$$ baryon with $$J^P = \tfrac{3}{2}^+$$ . To investigate the electromagnetic structure of these baryons, their magnetic moments and radiative decay widths are computed. Additionally, the two-body weak decay branching ratios of $$\Xi _c^0$$ are evaluated and compared with experimental data to assess the robustness of the approach. The two-body nonleptonic decays of $$\Xi _b^{'-}$$ are also analyzed, providing predictions for branching ratios that may be tested in future experiments. Overall, the results demonstrate the effectiveness of the parameter-reduction procedure and support its applicability in the spectroscopy of heavy flavor baryons.

India

Rameshri Patel

Manan Shah

Spain

Bhoomika Pandya

Singly heavy cascade baryon $$\Xi ^0_{c}$$ , $$\Xi ^{'0}_{c}$$ , $$\Xi ^-_{b}$$ & $$\Xi ^{'-}_{b}$$ spectroscopy in the relativistic framework of independent quark model

Recent observations from the DESI Collaboration indicate a preference for quintom dark energy, i.e., its equation of state evolves across the cosmological constant boundary $$w=-1$$ . It is well known that models with single perfect fluid or single scalar field minimally coupled to Einstein gravity develop perturbative instabilities around the crossing, thereby cannot realize the quintom scenario. In this paper, we propose a method to circumvent the instability problem of these models by considering the coupling of dark energy to the Nieh–Yan density within the framework of teleparallel gravity. We show that with this coupling the background evolution is not affected, but the dark energy perturbation is removed from the menu of dynamical degrees of freedom, thus avoiding the inherent difficulties in the old models. Furthermore, the Nieh–Yan coupling causes parity violation in gravitational waves, and this can be considered as a clear prediction of this mechanism.

Yuxuan Kang

Mingzhe Li

Changzhi Yi

Realization of quintom dark energy after DESI DR2 in Nieh–Yan modified teleparallel gravity