Using data samples of 102 million <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo stretchy="false">)</mo></math> events and 158 million <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> events collected by the Belle detector at the KEKB asymmetric-energy <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> collider, we search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">[</mo><mi>u</mi><mi>d</mi><mi>s</mi><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">]</mo></math> pentaquark states decaying to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi></math>. Using the first observations of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo>,</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> inclusive decays to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi></math>, we find evidence of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup></math> state with a local significance of 3.3 standard deviations, including statistical and systematic uncertainties. We measure the mass and width of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup></math> to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>4471.7</mn><mo>±</mo><mn>4.8</mn><mo>±</mo><mn>0.6</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mn>22</mn><mo>±</mo><mn>13</mn><mo>±</mo><mn>3</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, respectively. The branching fractions for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>P</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup></math> production are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo>/</mo><msub><mrow><mover accent="true"><mrow><mi>P</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo>+</mo><mi>anything</mi><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>3.5</mn><mo>±</mo><mn>2.0</mn><mo>±</mo><mn>0.2</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>6</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><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo>/</mo><mspace linebreak="goodbreak"></mspace><msub><mrow><mover accent="true"><mrow><mi>P</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo>+</mo><mi>anything</mi><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>2.9</mn><mo>±</mo><mn>1.7</mn><mo>±</mo><mn>0.4</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math>. The inclusive branching fractions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo>,</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi><mo>/</mo><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover></math> are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi><mo>/</mo><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover><mo>+</mo><mi>anything</mi><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>36.9</mn><mo>±</mo><mn>5.3</mn><mo>±</mo><mn>2.4</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi><mo>/</mo><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover><mo>+</mo><mi>anything</mi><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>22.3</mn><mo>±</mo><mn>5.7</mn><mo>±</mo><mn>3.1</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math>. We measure the visible cross section <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>σ</mi><mo stretchy="false">(</mo><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">Λ</mi><mo>/</mo><mover accent="true"><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>+</mo><mi>anything</mi><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>90</mn><mo>±</mo><mn>14</mn><mo>±</mo><mn>6</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mrow><mi>fb</mi></mrow></mrow></math> for the continuum production at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>10.52</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. In all cases, the first uncertainties are statistical and the second are systematic.

I. Adachi

L. Aggarwal

H. Ahmed

J.K. Ahn

H. Aihara

N. Akopov

M. Alhakami

A. Aloisio

N. Althubiti

D.M. Asner

H. Atmacan

V. Aushev

M. Aversano

R. Ayad

V. Babu

H. Bae

N.K. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

S. Bansal

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

V. Bhardwaj

B. Bhuyan

F. Bianchi

D. Biswas

D. Bodrov

A. Bolz

A. Boschetti

A. Bozek

M. Bračko

P. Branchini

R.A. Briere

T.E. Browder

A. Budano

S. Bussino

Q. Campagna

M. Campajola

L. Cao

G. Casarosa

C. Cecchi

J. Cerasoli

M.C. Chang

P. Chang

R. Cheaib

P. Cheema

B.G. Cheon

K. Chilikin

K. Chirapatpimol

H.E. Cho

K. Cho

S.J. Cho

S.K. Choi

S. Choudhury

J. Cochran

L. Corona

J.X. Cui

E. De La Cruz-Burelo

S.A. De La Motte

G. De Nardo

G. De Pietro

R. de Sangro

M. Destefanis

S. Dey

R. Dhamija

F. Di Capua

J. Dingfelder

Z. Doležal

I. Domínguez Jiménez

T.V. Dong

X. Dong

D. Dossett

K. Dugic

G. Dujany

P. Ecker

J. Eppelt

P. Feichtinger

T. Ferber

T. Fillinger

C. Finck

G. Finocchiaro

F. Forti

B.G. Fulsom

A. Gabrielli

E. Ganiev

M. Garcia-Hernandez

G. Gaudino

Search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4459</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow></msub><mo stretchy="false">(</mo><mn>4338</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">ϒ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>S</mi><mo>,</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> Inclusive Decays at Belle

We report a precise measurement of the ratio of branching fractions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">)</mo><mo>/</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><mo stretchy="false">)</mo></math> using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>980</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"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> data from the Belle experiment. We obtain a value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">)</mo><mo>/</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0.339</mn><mo>±</mo><mn>0.002</mn><mo>±</mo><mn>0.009</mn></math>, where the first and second uncertainties are statistical and systematic, respectively. This Belle result is consistent with the previous measurement from the CLEO experiment but has a fivefold improvement in precision. By combining our result with the world average <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><mo stretchy="false">)</mo></math>, we obtain the absolute branching fraction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>2.12</mn><mo>±</mo><mspace linebreak="goodbreak"></mspace><mn>0.01</mn><mo>±</mo><mn>0.05</mn><mo>±</mo><mn>0.10</mn><mo stretchy="false">)</mo><mo>%</mo></math>, where the uncertainties are statistical, systematic, and the uncertainty in the absolute branching fraction scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><mo stretchy="false">)</mo></math>, respectively. This measurement can shed light on hadronic decay mechanisms in charmed baryon decays.

M. Angelsmark

N. Anh Ky

T. Aushev

T. Bilka

A. Bobrov

A. Bondar

J. Borah

A. Di Canto

S. Dubey

D. Epifanov

Measurement of the branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>p</mi><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mn>0</mn></msup></math> at Belle

This review deals with measurements and future experiments of light pentaquark searches using hadron beams. Abstract Published by the Jagiellonian University 2025 authors

South Korea

Light Pentaquark Searches with Hadron Beams

We performed a search for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mi>L</mi></msub><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><mi>ν</mi><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover></math> decay using the data taken in 2021 at the J-PARC KOTO experiment. With newly installed counters and new analysis method, the expected background was suppressed to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0.252</mn><mo>±</mo><msub><mrow><mn>0.055</mn></mrow><mrow><mi>stat</mi></mrow></msub><msubsup><mrow><mtext> </mtext></mrow><mrow><mo>−</mo><msup><mrow><mn>0.067</mn></mrow><mrow><mi>syst</mi></mrow></msup></mrow><mrow><mo>+</mo><mn>0.052</mn></mrow></msubsup></mrow></math>. With a single event sensitivity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>9.33</mn><mo>±</mo><mn>0.0</mn><msub><mrow><mn>6</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.8</mn><msub><mrow><mn>4</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math>, no events were observed in the signal region. An upper limit on the branching fraction for the decay was set to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2.2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup></math> at the 90% confidence level (C.L.), which improved the previous upper limit from KOTO by a factor of 1.4. With the same data, a search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow></msub><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>X</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> was also performed, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>X</mi><mn>0</mn></msup></math> is an invisible boson with a mass ranging from 1 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>260</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>. For <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>X</mi><mn>0</mn></msup></math> with a mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>135</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mn>2</mn></msup></mrow></math>, an upper limit on the branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mi>L</mi></msub><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>X</mi><mn>0</mn></msup></math> was set to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.6</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup></math> at the 90% C.L.

United States

M. Farrington

Japan

M. Gonzalez

N. Grethen

K. Hanai

N. Hara

H. Haraguchi

China

Y.B. Hsiung

T. Inagaki

M. Katayama

T. Kato

Y. Kawata

E.J. Kim

H.M. Kim

A. Kitagawa

T.K. Komatsubara

K. Kotera

S.K. Lee

X. Li

G.Y. Lim

C. Lin

Y. Luo

T. Mari

T. Matsumura

I. Morioka

H. Nanjo

H. Nishimiya

Y. Noichi

T. Nomura

K. Ono

M. Osugi

P. Paschos

J. Redeker

T. Sato

Y. Sato

T. Shibata

N. Shimizu

T. Shinkawa

K. Shiomi

R. Shiraishi

S. Suzuki

Y. Tajima

N. Taylor

Y.C. Tung

Y.W. Wah

H. Watanabe

T. Wu

T. Yamanaka

H.Y. Yoshida

Search for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow></msub><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mi>ν</mi><mover accent="true"><mrow><mi>ν</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math> Decay at the J-PARC KOTO Experiment

A series of data samples was collected with the Belle II detector at the SuperKEKB collider from March 2019 to June 2022. We determine the integrated luminosities of these data samples using three distinct methodologies involving Bhabha (  $e^+e^- \to e^+e^-(n\gamma)$  ), digamma (  $e^+e^- \to e^+e^-(n\gamma)$  ), and dimuon (  $e^+e^- \to e^+e^-(n\gamma)$  ) events. The total integrated luminosity obtained with Bhabha, digamma, and dimuon events is (426.88 ± 0.03 ± 2.61) fb$^{−1}$, (429.28 ± 0.03 ± 2.62) fb$^{−1}$, and (423.99 ± 0.04 ± 3.83) fb$^{−1}$, where the first uncertainties are statistical and the second are systematic. The resulting total integrated luminosity obtained from the combination of the three methods is (427.87 ± 2.01) fb$^{−1}$.

L. Bierwirth

S. Das

G. de Marino

K. Dort

A. Fodor

A. Frey

Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle II experiment  

Using <math altimg='si4.svg'><mi mathvariant='normal'>&#978;</mi><mo stretchy='false'>(</mo><mn>1</mn><mi>S</mi><mo stretchy='false'>)</mo></math>, <math altimg='si5.svg'><mi mathvariant='normal'>&#978;</mi><mo stretchy='false'>(</mo><mn>2</mn><mi>S</mi><mo stretchy='false'>)</mo></math>, and <math altimg='si6.svg'><mi mathvariant='normal'>&#978;</mi><mo stretchy='false'>(</mo><mn>3</mn><mi>S</mi><mo stretchy='false'>)</mo></math> data collected by the Belle detector, we discover a new three-body decay, <math altimg='si7.svg'><mi mathvariant='normal'>&#937;</mi><msup><mrow><mo stretchy='false'>(</mo><mn>2012</mn><mo stretchy='false'>)</mo></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup><mo stretchy='false'>&#8594;</mo><mi mathvariant='normal'>&#926;</mi><mo stretchy='false'>(</mo><mn>1530</mn><mo stretchy='false'>)</mo><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover><mo stretchy='false'>&#8594;</mo><mi mathvariant='normal'>&#926;</mi><mi>&#960;</mi><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math>, with a significance of 5.2 <italic>&#963;</italic>. The mass of the <math altimg='si8.svg'><mi mathvariant='normal'>&#937;</mi><msup><mrow><mo stretchy='false'>(</mo><mn>2012</mn><mo stretchy='false'>)</mo></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup></math> is <math altimg='si9.svg'><mo stretchy='false'>(</mo><mn>2012.5</mn><mo>&#177;</mo><mn>0.7</mn><mo>&#177;</mo><mn>0.5</mn><mo stretchy='false'>)</mo></math> MeV and its effective couplings to <math altimg='si2.svg'><mi mathvariant='normal'>&#926;</mi><mo stretchy='false'>(</mo><mn>1530</mn><mo stretchy='false'>)</mo><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> and <math altimg='si3.svg'><mi mathvariant='normal'>&#926;</mi><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> are <math altimg='si10.svg'><mo stretchy='false'>(</mo><msubsup><mrow><mn>39</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>39</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mn>31</mn></mrow></msubsup><mo>&#177;</mo><mn>9</mn><mo stretchy='false'>)</mo><mo>&#215;</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>2</mn></mrow></msup></math> and <math altimg='si11.svg'><mo stretchy='false'>(</mo><mn>1.7</mn><mo>&#177;</mo><mn>0.3</mn><mo>&#177;</mo><mn>0.3</mn><mo stretchy='false'>)</mo><mo>&#215;</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>2</mn></mrow></msup></math>, where the first uncertainties are statistical and the second are systematic. The ratio of the branching fraction for the three-body decay to that for the two-body decay to <math altimg='si3.svg'><mi mathvariant='normal'>&#926;</mi><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> is <math altimg='si12.svg'><mn>0.99</mn><mo>&#177;</mo><mn>0.26</mn><mo>&#177;</mo><mn>0.06</mn></math>, assuming isospin symmetry.

S. Jia

C.P. Shen

C.Z. Yuan

J. Bennett

Y. Choi

D. Ferlewicz

V. Gaur

A. Garmash

A. Giri

P. Goldenzweig

E. Graziani

D. Greenwald

K. Gudkova

C. Hadjivasiliou

D. Herrmann

W.S. Hou

N. Ipsita

A. Ishikawa

R. Itoh

M. Iwasaki

W.W. Jacobs

Y. Jin

Observation of <math altimg='si1.svg'><mi mathvariant='normal'>&#937;</mi><msup><mrow><mo stretchy='false'>(</mo><mn>2012</mn><mo stretchy='false'>)</mo></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup><mo stretchy='false'>&#8594;</mo><mi mathvariant='normal'>&#926;</mi><mo stretchy='false'>(</mo><mn>1530</mn><mo stretchy='false'>)</mo><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> and measurement of the effective couplings of &#937;(2012) &#8722; to <math altimg='si2.svg'><mi mathvariant='normal'>&#926;</mi><mo stretchy='false'>(</mo><mn>1530</mn><mo stretchy='false'>)</mo><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math> and <math altimg='si3.svg'><mi mathvariant='normal'>&#926;</mi><mover accent='true'><mrow><mi>K</mi></mrow><mrow><mo stretchy='false'>&#175;</mo></mrow></mover></math>