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.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

Italy

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

United States

R.A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

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>

We suggest a new method to analyse the rare $\textit{D}$ → $\textit{Pℓ}$ $\textit{ℓ}$ decays ($\textit{P}$ = $\textit{π}$, $\textit{K}$), combining QCD light-cone sum rules (LCSR) with hadronic dispersion relations. As our main study case, we consider the $\textit{D}$ → $\textit{π}$ $\textit{ℓ}$ $\textit{ℓ}$ mode which attracts much of interest from the point of view of GIM cancellation and potential new sources of the FCNC $\textit{c}$ → $\textit{u}$ transitions. The hadronic amplitude of this decay is dominated by the combination of weak annihilation with the emission of a virtual photon. This $\textit{D}$ → $\textit{π}$ $\textit{γ}$ amplitude is calculated at spacelike photon virtualities, −$\textit{q}$ ≫ $$ {\Lambda}_{\textrm{QCD}}^2 $$ , using LCSR with pion distribution amplitudes. The LCSR results are then fitted to the hadronic dispersion relation in the variable $\textit{q}$ . The fit allows us to determine relative phases of the $\textit{ρ}$-, $\textit{ω}$- and $\textit{ϕ}$-meson terms and to estimate the contributions of heavier hadronic states. The latter are parameterized in two different ways: first, with a $\textit{z}$-expansion and second, using a model with excited vector-meson resonances. The resulting $\textit{D}$ → $\textit{π}$ $\textit{ℓ}$ $\textit{ℓ}$ width obtained from the LCSR-assisted dispersion relation is not much smaller than the current upper bound measured by LHCb collaboration. In comparison with our result for the dominant $\textit{D}$ → $\textit{π}$ $\textit{γ}$ transition, the contribution induced by the short distance $\textit{c}$ → $\textit{uℓ}$ $\textit{ℓ}$ quark transition generated by the effective $\textit{O}$ operator in Standard Model turns out to be practically invisible. To detect its effect, one readily needs an enhancement of the coefficient $\textit{C}$ from non-standard effects by many orders of magnitude. We also establish new $\textit{U}$-spin symmetry relations between the amplitudes of $\textit{D}$ → $\textit{Pℓ}$ $\textit{ℓ}$ decays and apply our method to the Cabibbo-favoured modes $$ {D}_s^{+}\to {\pi}^{+}{\ell}^{+}{\ell}^{-} $$ and $$ {D}^0\to {\overline{K}}^0{\ell}^{+}{\ell}^{-} $$ which proceed via the same weak annihilation mechanism.

Anshika Bansal

Alexander Khodjamirian

Thomas Mannel

$\textit{D}$ → $\textit{Pℓ}$

In the present work, we study the reactions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><mi>η</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>η</mi></math>, and find that the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> state plays a dominant role. At the quark level, the external and internal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-emission mechanisms are taken into account, which can hadronize into the final states, and then the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> state is generated from the final state interaction. In addition, the contributions of other intermediate resonances, such as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi><mo stretchy="false">(</mo><mn>770</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1020</mn><mo stretchy="false">)</mo></math>, are also considered. We make a combined fit of the invariant mass spectra measured by the Belle and BESIII Collaborations, where the results are in good agreement with the experiments, and the signal of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> shows great significance. Furthermore, the antisymmetry data for the production of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><msup><mo stretchy="false">)</mo><mo>−</mo></msup></math> are described well in the combined fit.

Sara Rahmani

Wei Liang

Yu-Wen Peng

Yu Lu

De-Liang Yao

Chu-Wen Xiao

Role of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> in the decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><mi>η</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>η</mi></math>

Using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>20.3</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> of <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></math> collision data collected at a center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi mathvariant="normal">c</mi><mn>.</mn><mi mathvariant="normal">m</mi><mn>.</mn></mrow></msub><mo>=</mo><mn>3.773</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> with the BESIII detector operating at the BEPCII collider, we determine the branching fraction of the leptonic 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><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></mrow></math> to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>4.034</mn><mo>±</mo><mn>0.08</mn><msub><mrow><mn>0</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.04</mn><msub><mrow><mn>0</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>. Interpreting our measurement with knowledge of the Fermi coupling constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>G</mi><mi>F</mi></msub></math>, the masses of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>μ</mi><mo>+</mo></msup></math> as well as the lifetime of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup></math>, we determine <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>f</mi></mrow><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></msub><mo stretchy="false">|</mo><msub><mrow><mi>V</mi></mrow><mrow><mi>c</mi><mi>d</mi></mrow></msub><mo stretchy="false">|</mo><mo>=</mo><mo stretchy="false">(</mo><mn>48.02</mn><mo>±</mo><mn>0.4</mn><msub><mrow><mn>8</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.2</mn><msub><mrow><mn>4</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo>±</mo><mn>0.1</mn><msub><mrow><mn>2</mn></mrow><mrow><mtext>input</mtext></mrow></msub><mo>±</mo><mn>0.1</mn><msub><mrow><mn>5</mn></mrow><mrow><mi>EM</mi></mrow></msub><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math> after taking into account necessary radiative corrections. This result is a factor of 2.3 more precise than the previous best measurement. Using the value of the magnitude of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>c</mi><mo>→</mo><mi>d</mi></mrow></math> Cabibbo-Kobayashi-Maskawa matrix element <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>c</mi><mi>d</mi></mrow></msub><mo stretchy="false">|</mo></math> given by the global standard model fit, we obtain the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup></math> decay constant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>f</mi></mrow><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></msub><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>213.5</mn><mo>±</mo><msub><mrow><mn>2.1</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><msub><mrow><mn>1.1</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo>±</mo><msub><mrow><mn>0.8</mn></mrow><mrow><mtext>input</mtext></mrow></msub><mo>±</mo><msub><mrow><mn>0.7</mn></mrow><mrow><mi>EM</mi></mrow></msub><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. Alternatively, using the value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><msup><mi>D</mi><mo>+</mo></msup></msub></math> from a precise lattice quantum chromodynamics calculation, we extract <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">|</mo><msub><mrow><mi>V</mi></mrow><mrow><mi>c</mi><mi>d</mi></mrow></msub><mo stretchy="false">|</mo><mo>=</mo><mn>0.2265</mn><mo>±</mo><mn>0.002</mn><msub><mrow><mn>3</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.001</mn><msub><mrow><mn>1</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo>±</mo><mspace linebreak="goodbreak"></mspace><mn>0.000</mn><msub><mrow><mn>9</mn></mrow><mrow><mtext>input</mtext></mrow></msub><mo>±</mo><mn>0.000</mn><msub><mrow><mn>7</mn></mrow><mrow><mi>EM</mi></mrow></msub></mrow></math>.

Q. An

Z.Y. Chen

Y. Fang

Y.N. Gao

Precision Measurement of the Branching Fraction of <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><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></mrow></math>

Employing a unified Dyson-Schwinger/Bethe-Salpeter equations approach, we calculate the strong decay couplings <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><mi>D</mi><mi>π</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><mi>B</mi><mi>π</mi></math> within the so-called impulse-approximation in the moving frame. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><mi>B</mi><mi>π</mi></math> estimation is reported for the first time based on a Poincaré invariant computation of the associated Bethe-Salpeter amplitudes. Our predictions yield <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><msup><mi>D</mi><mo>*</mo></msup><mi>D</mi><mi>π</mi></mrow></msub><mo>=</mo><mn>16.2</mn><msubsup><mn>2</mn><mrow><mo>−</mo><mn>0.01</mn></mrow><mrow><mo>+</mo><mn>0.03</mn></mrow></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><msup><mi>B</mi><mo>*</mo></msup><mi>B</mi><mi>π</mi></mrow></msub><mo>=</mo><mn>40.0</mn><msubsup><mn>9</mn><mrow><mo>−</mo><mn>1.37</mn></mrow><mrow><mo>+</mo><mn>1.51</mn></mrow></msubsup></math>, along with corresponding static strong couplings of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>g</mi><mo stretchy="false">^</mo></mover><mi>D</mi></msub><mo>=</mo><mn>0.5</mn><msubsup><mn>5</mn><mrow><mo>−</mo><mo>&lt;</mo><mn>0.01</mn></mrow><mrow><mo>+</mo><mo>&lt;</mo><mn>0.01</mn></mrow></msubsup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>g</mi><mo stretchy="false">^</mo></mover><mi>B</mi></msub><mo>=</mo><mn>0.5</mn><msubsup><mn>0</mn><mrow><mo>−</mo><mn>0.02</mn></mrow><mrow><mo>+</mo><mn>0.02</mn></mrow></msubsup></math>, which are consistent with recent experimental and lattice data.

Spain

Y.Z. Xu

K. Raya

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><mi>D</mi><mi>π</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><mi>B</mi><mi>π</mi></math> couplings from Dyson-Schwinger equations framework

Non-geometric flux vacua have recently been revisited, leading to the remarkable discovery of isolated 4D $$ \mathcal{N} $$ = 1 supersymmetric Minkowski vacua. These constructions rely on the non-renormalization of the superpotential, which is supported by heuristic arguments. Given the significance of verifying the existence of these isolated M-theory-like vacua, we present alternative symmetry-based arguments that arrive at the same conclusion. Additionally, we leverage these symmetries to argue for the existence of unstable dS solutions as well as supersymmetric AdS solutions.

Shi Chen

Damian Heisteeg

Cumrun Vafa

Symmetries and M-theory-like vacua in four dimensions

The study of neutral $\textit{D}$-meson mixing provides a unique probe of long-distance effects in the charm sector, where Standard Model contributions are dominated by nonperturbative effects. In this work, we investigate the feasibility of using spectral reconstruction techniques within lattice QCD to compute the long-distance contributions to $\textit{D}$ − $$ {\overline{D}}^0 $$ mixing. After outlining the general formalism describing neutral meson mixing in the charm sector, we focus on the determination of the mixing amplitudes and the dimensionless parameters $\textit{x}$ = ∆$\textit{m}$ $\textit{/}$Γ and $\textit{y}$ = ∆Γ $\textit{/}$(2Γ ), which respectively encode the mass and width differences between the $\textit{D}$-meson mass eigenstates. We discuss in detail the required theoretical and computational framework, including the definition and renormalization of the four-quark operators entering the ∆$\textit{C}$ = 1 weak Hamiltonian, and strategies for evaluating the relevant correlation functions employing variance-reduction techniques. To extract the mixing ampli- tudes, we explore methods for reconstructing the spectral density from lattice correlators, providing preliminary assessments of the data quality required to reach the scaling regime, where the smearing width is small enough to yield physically meaningful results. Our findings lay the groundwork for future precision determinations of long-distance contributions to $\textit{D}$-meson mixing from first principles.

Switzerland

Matteo Carlo

Felix Erben

United Kingdom

Maxwell Hansen

Long distance contributions to neutral $\textit{D}$-meson mixing from lattice QCD

We measure the time-integrated <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetry in <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><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> decays reconstructed in <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><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></mrow></math> events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>428</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, respectively. To infer the flavor of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup></math> meson, we exploit the correlation between the flavor of the reconstructed decay and the electric charges of particles reconstructed in the rest of the <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><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></mrow></math> event. This results in a sample which is independent from any other previously used at Belle or Belle II. The result, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>A</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.3</mn><mo>±</mo><mn>2.0</mn><mo>±</mo><mn>0.2</mn><mo stretchy="false">)</mo><mo>%</mo></mrow></math>, where the first uncertainty is statistical and the second systematic, is consistent with previous determinations and with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> symmetry.

I. Adachi

Y. Ahn

N. Akopov

S. Alghamdi

M. Alhakami

A. Aloisio

N. Althubiti

K. Amos

M. Angelsmark

N. Anh Ky

C. Antonioli

D.M. Asner

H. Atmacan

T. Aushev

M. Aversano

R. Ayad

V. Babu

H. Bae

N.K. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

M. Barrett

M. Bartl

J. Baudot

A. Baur

A. Beaubien

F. Becherer

J. Becker

J.V. Bennett

F.U. Bernlochner

V. Bertacchi

M. Bertemes

E. Bertholet

M. Bessner

S. Bettarini

B. Bhuyan

T. Bilka

D. Biswas

A. Bobrov

D. Bodrov

A. Bondar

J. Borah

A. Boschetti

A. Bozek

M. Bračko

P. Branchini

T.E. Browder

A. Budano

S. Bussino

M. Campajola

L. Cao

G. Casarosa

Measurement of the time-integrated <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetry in <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><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> decays using opposite-side flavor tagging at Belle and Belle II