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

Belgium

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.

China

R.Z. Jiang

Z.L. Li

Y.J. Li

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

Pulsars possess strong dipole magnetic fields that can source axion fields through the axion-photon interaction. Pulsars may therefore be surrounded by axion field configurations oscillating with the pulsar’s rotational period. These axions could be detected by observing their effect on the polarization of the pular’s emission. In this paper, we use time resolved observations of the optical polarization of the Crab pulsar to place bounds on the axion-photon coupling, demonstrating the potential of time resolved pulsar birefringence in the search for axions.

United Kingdom

Francesca Chadha-Day

Tanmay Kumar Poddar

Searching for axions with time resolved pulsar polarimetry

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

We investigate the collider signatures of the minimal framework for quark-lepton unification at a scale not far from the electroweak symmetry breaking scale. This theory predicts a rich spectrum of new fields, including one vector leptoquark, two scalar leptoquarks, a color-octet scalar, and an additional Higgs doublet. Neutrino masses are generated via the inverse seesaw mechanism, facilitating viable matter unification at the low scale. We find that this theory predicts that in many cases the dominant leptoquark decays are to the third generation Standard Model quarks and leptons. We identify key experimental signatures at the Large Hadron Collider, evaluate and discuss the limits from current measurements, and outline potential strategies for probing this theory in the near future.

Jon Butterworth

Hridoy Debnath

Pavel Fileviez Pérez

Peng Wang

Quark-lepton unification signatures

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 introduce the Krylov distribution <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">D</mi><mo stretchy="false">(</mo><mi>ξ</mi><mo stretchy="false">)</mo></math>, a static Krylov-space diagnostic that characterizes how inverse-energy response is organized in Hilbert space. The central object is the resolvent-dressed state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>H</mi><mo>−</mo><mi>ξ</mi><msup><mo stretchy="false">)</mo><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo stretchy="false">|</mo><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">⟩</mo></math>, whose decomposition in the Krylov basis generated from a reference state defines a normalized distribution over Krylov levels. Unlike conventional spectral functions, which resolve response solely along the energy axis, the Krylov distribution captures how the resolvent explores the dynamically accessible subspace as the spectral parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ξ</mi></math> is varied. Using asymptotic analysis, exact results in solvable models, and numerical studies of an interacting spin chain, we identify three universal regimes: saturation outside the spectral support, extensive growth within continuous spectra, and sublinear or logarithmic scaling near spectral edges and quantum critical points. We further show that fidelity susceptibility and the quantum geometric tensor admit natural decompositions in terms of Krylov-resolved resolvent amplitudes.

Iran

Mohsen Alishahiha

Mohammad Javad Vasli

Krylov distribution

We introduce a three-dimensional quantum field theory with an infinite-dimensional symmetry, realized explicitly through a centrally extended affine graded Lie algebra. This symmetry is a direct three-dimensional generalization of the chiral symmetry in the Wess-Zumino-Witten model. Upon performing radial quantization, we construct the Fock space of the theory and, via a three-dimensional analog of the state-operator correspondence, we demonstrate that the algebra of local operators is endowed with the structure of a raviolo vertex algebra. Accordingly, this setup provides a framework for extending the methods of two-dimensional conformal field theory to three dimensions, and we expect it to lay the groundwork for exact methods in three-dimensional quantum field theory.

Hank Chen

Joaquin Liniado

Infinite dimensional topological-holomorphic symmetry in three dimensions

The standard parity-doublet model with its mass-mixing mechanism fails to describe the axial charge <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mi>A</mi></msub></math> of the nucleon. While <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mi>A</mi></msub><mo>=</mo><mn>1</mn></math> in the original Gell-Mann–Levy model, which reproduces the Adler-Bell-Jackiw anomaly of QCD, in the presence of a chirally invariant baryon mass the mass mixing leads to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mi>A</mi></msub><mo>&lt;</mo><mn>1</mn></math>, whereas phenomenologically it is about 1.28. We propose to remedy this problem by introducing kinetic-mixing terms corresponding to meson-baryon derivative couplings, similar in spirit to the two-mixing-angle scenario of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>−</mo><msup><mi>η</mi><mo>′</mo></msup></math> mixing. This extended parity-doublet model contains five parameters in the effective baryonic Lagrangian. Three of them can be determined by using the empirical results for the axial charge of the nucleon together with the masses of the nucleon and its parity partner, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>N</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>1535</mn><mo stretchy="false">)</mo></math> resonance. We discuss various options of how to determine the remaining parameters, touching upon the mass of both parity partners if the chiral condensate is put to zero, the mass of the nucleon in the chiral limit, and the values of meson-baryon coupling constants related to the decays of the resonance to pion-nucleon and sigma-nucleon.

Cyprus

Germany

Christian Kummer

Sweden

Stefan Leupold

Lorenz von Smekal

Kinetic mixing and axial charges in the parity-doublet model

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