<p>We present a measurement of <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> from a simultaneous study of the charmless semileptonic decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>ρ</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo><mo>=</mo><mi>e</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>μ</mi></mrow></math>. This measurement uses a data sample of 387 million <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover></math> meson pairs recorded by the Belle II detector at the SuperKEKB electron-positron collider between 2019 and 2022. The two decays are reconstructed without identifying the partner <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> mesons. We simultaneously measure the differential branching fractions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>−</mo></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>ρ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays as functions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math> (momentum transfer squared). From these, we obtain total branching fractions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.516</mn><mo>±</mo><mn>0.042</mn><mo stretchy="false">(</mo><mrow><mi>stat</mi></mrow><mo stretchy="false">)</mo><mo>±</mo><mn>0.059</mn><mo stretchy="false">(</mo><mrow><mi>syst</mi></mrow><mo stretchy="false">)</mo><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</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><msup><mrow><mi>B</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>ρ</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub><mo stretchy="false">)</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>1.625</mn><mo>±</mo><mn>0.079</mn><mo stretchy="false">(</mo><mrow><mi>stat</mi></mrow><mo stretchy="false">)</mo><mo>±</mo><mn>0.180</mn><mo stretchy="false">(</mo><mrow><mi>syst</mi></mrow><mo stretchy="false">)</mo><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>. By fitting the measured <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>−</mo></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> partial branching fractions as functions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math>, together with constraints on the nonperturbative hadronic contribution from lattice QCD calculations, we obtain <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>3.93</mn><mo>±</mo><mn>0.09</mn><mo>±</mo><mn>0.13</mn><mo>±</mo><mn>0.19</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math>. Here, the first uncertainty is statistical, the second is systematic, and the third is theoretical.</p>

I. Adachi

L. Aggarwal

H. Aihara

N. Akopov

A. Aloisio

N. Althubiti

N. Anh Ky

D.M. Asner

H. Atmacan

T. Aushev

V. Aushev

M. Aversano

R. Ayad

V. Babu

H. Bae

S. Bahinipati

P. Bambade

Sw. Banerjee

S. Bansal

M. Barrett

J. Baudot

M. Bauer

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

F. Bianchi

L. Bierwirth

T. Bilka

D. Biswas

A. Bobrov

D. Bodrov

A. Bolz

J. Borah

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

L. Corona

J.X. Cui

F. Dattola

E. De La Cruz-Burelo

S.A. De La Motte

G. De Nardo

M. De Nuccio

G. De Pietro

R. de Sangro

M. Destefanis

S. Dey

R. Dhamija

A. Di Canto

F. Di Capua

J. Dingfelder

Z. Doležal

I. Domínguez Jiménez

T.V. Dong

M. Dorigo

D. Dorner

K. Dort

D. Dossett

S. Dreyer

S. Dubey

K. Dugic

G. Dujany

P. Ecker

M. Eliachevitch

P. Feichtinger

T. Ferber

T. Fillinger

C. Finck

Determination of <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> from simultaneous measurements of untagged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>−</mo></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>ρ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays

<p>Recent measurements of the lepton flavor universality ratios <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>R</mi><mi>K</mi><mrow><mi>μ</mi><mi>e</mi></mrow></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>R</mi><msup><mi>K</mi><mo>*</mo></msup><mrow><mi>μ</mi><mi>e</mi></mrow></msubsup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mrow><mo stretchy="false">(</mo><mi>K</mi><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup><mo stretchy="false">)</mo></mrow><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup><mrow><mo stretchy="false">(</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></mrow></math> at LHCb align with the Standard Model predictions, necessitating a search for the complementary decay modes. In this context, we derive the angular decay distributions of the four-fold <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi><mo stretchy="false">→</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> decays, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> is an axial-vector meson, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo>=</mo><mi>ρ</mi><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>P</mi><mo>=</mo><mi>K</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>π</mi></mrow></math>. Considering the weak effective Hamiltonian with vector and axial-vector new physics operators, and employing the helicity formalism, we obtain the four-dimensional differential decay distributions and extract various physical observables. These include differential branching ratios, lepton forward-backward asymmetry, forward-backward asymmetry for transversely polarized <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> meson, longitudinal and transverse polarization fractions of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> meson, and normalized angular coefficients with longitudinally and transversely polarized final state vector meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi></math>, in the cascade decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi></math>. Based on the latest global fit analysis data for all <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi></math> transitions, we predict the results of these observables in various bins of the square of the momentum transfer <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>. Our findings indicate that these physical observables are not only sensitive to new physics but also can differentiate between various new physics scenarios in certain kinematical regions. The precise measurements of these observables in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> decays in current and future experiments will provide opportunities for complementary searches for physics beyond the Standard Model in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> decays.</p>

Pakistan

Faisal Munir Bhutta

Canada

Abdur Rehman

M. Jamil Aslam

Ishtiaq Ahmed

Saadi Ishaq

Angular observables of the four-fold <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> decays in and beyond the Standard Model

The hyperon potential, particularly its behavior at high densities, is crucial for resolving the “hyperon puzzle” in neutron stars and for advancing our understanding of the strong interactions between strange and non-strange particles in high baryon density environments. Using the hadronic transport model AMPT-HC, hypernucleus-nucleus collision is studied. It is found that at beam energies below the threshold for hyperon production, the hyperon elliptic flow exhibits noticeable asymmetry between the positive and negative rapidity regions and is sensitive to the strength of the hyperon potential, especially in the large negative rapidity region. One can extract the hyperon potential approximately twice the saturation density based on the hyperon elliptic flow in the negative rapidity region, and the hyperon potential around the saturation density based on the hyperon elliptic flow in the positive rapidity region.

China

Gao-Chan Yong

Probing Λ potential via its <italic>v</italic> <inf>2</inf> flow in hypernuclei-induced reaction

This brief review is dedicated to the memory of Maxim V. Polyakov and his pioneering contributions to pentaquark physics. We focus on his seminal 1997 work with Diakonov and Petrov that predicted the ${\mit \Theta }^+$ pentaquark, a breakthrough that initiated an intense period of research in hadron physics. The field faced a significant setback when the CLAS Collaboration at Jefferson Lab reported null results in 2006, leading to a dramatic decline in light-pentaquark research. Nevertheless, Maxim maintained his scientific conviction, supported by continued positive signals from the DIANA and LEPS collaborations. Through recent experimental findings on the ${\mit \Theta }^+$ and the nucleon-like resonance $N^*(1685)$, we examine how Polyakov’s theoretical insights, particularly the prediction of a narrow width (${\mit \Gamma } \approx 0.5$–$1.0$ MeV), remain relevant to our understanding of the ${\mit \Theta }^+$ light pentaquark. Abstract Published by the Jagiellonian University 2025 authors

South Korea

H.-Ch. Kim

Pentaquarks and Maxim V. Polyakov

A search is presented for the pair production of new heavy resonances, each decaying into a top quark (t) or antiquark and a gluon (g). The analysis uses data recorded with the CMS detector from proton–proton collisions at a center-of-mass energy of 13 $$\,\text {Te}\hspace{-.08em}\text {V}$$ at the LHC, corresponding to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ . Events with one muon or electron, multiple jets, and missing transverse momentum are selected. After using a deep neural network to enrich the data sample with signal-like events, distributions in the scalar sum of the transverse momenta of all reconstructed objects are analyzed in the search for a signal. No significant deviations from the standard model prediction are found. Upper limits at 95% confidence level are set on the product of cross section and branching fraction squared for the pair production of excited top quarks in the $$\text {t}^{*} \rightarrow {\text {t}} {\text {g}} $$ decay channel. The upper limits range from 120 to 0.8 $$\,\text {fb}$$ for a $$\text {t}^{*} $$ with spin-1/2 and from 15 to 1.0 $$\,\text {fb}$$ for a $$\text {t}^{*} $$ with spin-3/2. These correspond to mass exclusion limits up to 1050 and 1700 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ for spin-1/2 and spin-3/2 $$\text {t}^{*} $$ particles, respectively. These are the most stringent limits to date on the existence of $$\text {t}^{*} \rightarrow {\text {t}} {\text {g}} $$ resonances.

Armenia

A. Hayrapetyan

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

T. Laer

P. Mechelen

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

S. Lowette

I. Makarenko

D. Müller

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

J. Jaramillo

A. Khalilzadeh

F. Khan

K. Lee

A. Malara

S. Paredes

M. Shahzad

L. Thomas

M. Bemden

C. Velde

P. Vanlaer

M. Coen

D. Dobur

G. Gokbulut

Y. Hong

J. Knolle

L. Lambrecht

D. Marckx

K. Amarilo

K. Skovpen

N. Bossche

J. Linden

L. Wezenbeek

A. Benecke

A. Bethani

G. Bruno

C. Caputo

J. Favereau De Jeneret

C. Delaere

I. Donertas

A. Giammanco

A. Guzel

Search for pair production of heavy particles decaying to a top quark and a gluon in the lepton+jets final state in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$