<p>Using data samples corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.9</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> collected with the BESIII detector operating at the BEPCII storage ring at the center-of-mass energies of 4.84, 4.92, and 4.95 GeV, we search for the exotic charmoniumlike 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>0</mn><mrow><mo>−</mo><mo>−</mo></mrow></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo></math>, in 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>η</mi><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo></math> with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>η</mi><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math>. No significant signal of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo></math> resonance state is observed. Upper limits on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi><mo stretchy="false">(</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>η</mi><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo><mo stretchy="false">)</mo><mo>·</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>η</mi><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi><mo stretchy="false">(</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><mi>η</mi><mi>η</mi><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><mo stretchy="false">)</mo></math> at the 90% confidence level are determined for each energy point.</p>

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Italy

C.S. Akondi

Germany

R. Aliberti

A. Amoroso

Q. An

Y.H. An

Y. Bai

JINR

O. Bakina

H.R. Bao

X.L. Bao

M. Barbagiovanni

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M.B. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

United States

R.A. Briere

A. Brueggemann

D. Cabiati

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

T.T. Chang

G.R. Che

Y.Z. Che

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.M. Chen

T. Chen

W. Chen

X.R. Chen

X.T. Chen

X.Y. Chen

Y.B. Chen

Y.Q. Chen

Z.K. Chen

J. Cheng

L.N. Cheng

South Korea

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

United Kingdom

J. Cottee-Meldrum

H.L. Dai

J.P. Dai

X.C. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denisenko

M. Destefanis

F. De Mori

E. Di Fiore

X.X. Ding

Y. Ding

Y.X. Ding

Yi. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Shaoxu Du

X.L. Du

Y.Q. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

Jin Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

L. Fava

Search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ψ</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>4360</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>η</mi><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> through 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>η</mi><mi>η</mi><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math>

In this article, we test the validity of the weak cosmic censorship conjecture (wCCC) in the background of a quantum Kerr–de Sitter (qKdS) black hole, incorporating exact backreaction from quantum matter fields. Using a test particle approach, we analyze whether an extremal qKdS black hole can be over-extremized to expose a naked singularity. Our results indicate that the black hole remains stable against horizon-destroying processes induced by infalling matter. Quantum corrections enhance the horizon’s robustness rather than destabilize it, offering further evidence that wCCC remains preserved in the presence of quantum effects.

India

Ankit Anand

Ankur Dey

Kerr–de Sitter black holes: quantum aspects and cosmic censorship conjecture

We investigate the superradiant instability of Ayón-Beato–García–de Sitter (ABG-dS) black holes under charged scalar field perturbations, employing both time-domain evolutions and frequency-domain computations. We demonstrate that the instability manifests exclusively for the spherically symmetric mode with $$\ell =0$$ for both massless and massive scalar field perturbations. In contrast, asymptotically flat ABG black holes remain stable in the massless limit, a finding that highlights the crucial role of the cosmological horizon in providing a confining boundary. We further analyze the dependence of the instability growth rate on the cosmological constant $$\Lambda $$ , the black hole charge $\textit{Q}$, the scalar field charge $\textit{q}$, and the scalar field mass $$\mu $$ . We find that the growth rate peaks at intermediate values of $$\Lambda $$ and $\textit{q}$, and increases monotonically with $\textit{Q}$. Conversely, an increase in the scalar field mass $$\mu $$ suppresses the instability, eventually quenching it when $$\mu $$ is sufficiently large. Compared with Reissner–Nordström–de Sitter black holes, ABG-dS black holes exhibit distinct instability characteristics, which arise from the modified electrostatic potential induced by nonlinear electrodynamics.

Yizhi Zhan

Hengyu Xu

Haowei Chen

Shao-Jun Zhang

Charged superradiant instability of spherically symmetric regular black holes in de Sitter spacetime: time- and frequency-domain analysis

We construct charges for four-dimensional spacetimes with a non-vanishing cosmological constant, including charges that are not conserved because of a leaky boundary and charges associated with corner terms in the symplectic current. The construction leads to manifestly finite charges for any choice of boundary conditions, and reveals new charges in partial Bondi gauge for an enlarged class of field configurations which are not fully on-shell, including a Weyl charge for conformal boundary conditions. In addition, we generalize the variational principle for AdS gravity with Dirichlet boundary conditions to a wedge of spacetime where the conformal boundary includes a corner. The boundary data is completely general, with no conditions restricting time dependence or the determinant of the metric. The Ward identities associated with boundary diffeomorphisms are shown to reproduce the evolution equations for the mass and angular momentum of fully on-shell field configurations.

Robert McNees

Canada

France

Céline Zwikel

(Anti)-de Sitter with leaky boundaries and corners

Using data samples collected by the Belle and Belle II experiments at the Υ(4$\textit{S}$) resonance with integrated luminosities of 571 fb and 365 fb , respectively, we measure the pseudoscalar $\textit{B}$-meson mass difference to be $\textit{m}$($\textit{B}$ ) − $\textit{m}$($\textit{B}$ ) = (0$\textit{.}$495 ± 0$\textit{.}$024 ± 0$\textit{.}$005) MeV/$\textit{c}$ . The results are based on a simultaneous fit to the variable $${\overline{M} }_{bc}$$ , which is related to the $\textit{B}$ momentum, for $\textit{B}$ and $\textit{B}$ candidates; and to the energy dependence of $$\mathcal{R}=\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0}) / \sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})$$ , which is measured using changes in the average center-of-mass energy over the data taking periods. The phase-space hypothesis $$\mathcal{R}={({p}_{{B}^{0}} /{p}_{{B}^{+}})}^{3}$$ , upon which previous measurements rely, is strongly disfavored by our fit; the measured mass-difference value for the phase-space hypothesis also differs significantly from our measurement. We constrain $$\mathcal{R}$$ in a broader energy range than covered by the direct measurement and extract the energy dependence of $$\mathcal{R}$$ in the range from the $$B\overline{B }$$ threshold up to 10.59 GeV. We interpret the results using a phenomenological model and constrain the parameters of the $$B\overline{B }$$ potential in the isovector channel.

M. Abumusabh

I. Adachi

L. Aggarwal

H. Ahmed

Y. Ahn

H. Aihara

N. Akopov

S. Alghamdi

M. Alhakami

A. Aloisio

N. Althubiti

K. Amos

N. Anh Ky

C. Antonioli

D. Asner

H. Atmacan

T. Aushev

R. Ayad

V. Babu

N. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

M. Barrett

M. Bartl

J. Baudot

A. Beaubien

F. Becherer

J. Becker

J. Bennett

F. Bernlochner

V. Bertacchi

M. Bertemes

E. Bertholet

M. Bessner

S. Bettarini

V. Bhardwaj

T. Bilka

D. Biswas

D. Bodrov

A. Bondar

G. Bonvicini

J. Borah

A. Boschetti

A. Bozek

M. Bračko

P. Branchini

R. Briere

T. Browder

A. Budano

S. Bussino

Q. Campagna

M. Campajola

G. Casarosa

C. Cecchi

P. Chang

P. Cheema

L. Chen

B. Cheon

C. Cheshta

H. Chetri

K. Chilikin

J. Chin

K. Chirapatpimol

H.E. Cho

K. Cho

S.J. Cho

S. Choudhury

S. Chutia

Measurements of the mass difference $\textit{m}$($\textit{B}$ 0) $\textit{− m}$($\textit{B}$ +) and the energy dependence of the cross-section ratio $$\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0})/\sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})$$ at Belle and Belle II