The <italic>&#947;d</italic>&#8239;&#8594;&#8239; <italic>K</italic> 0&#923; <italic>p</italic> reaction has been studied to search for a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state using the LEPS2 solenoid spectrometer at SPring-8. A localized enhancement concentrated at low <italic>q</italic> is observed in the ( <italic>M</italic> <inf>&#923;<italic>p</italic></inf>, <italic>q</italic>) distribution below the <math altimg='si8.svg'><mrow><msup><mi>K</mi><mo>&#8722;</mo></msup><mi>p</mi><mi>p</mi></mrow></math> mass threshold, where <italic>M</italic> <inf>&#923;<italic>p</italic></inf> is the &#923; <italic>p</italic> invariant mass and <math altimg='si31.svg'><mrow><mrow><mi>q</mi><mo>&#8801;</mo><mo>|</mo></mrow><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><mi>&#947;</mi></msub><mo linebreak='goodbreak'>&#8722;</mo><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><msup><mi>K</mi><mn>0</mn></msup></msub><mrow><mo>|</mo><mo>=</mo><mo>|</mo></mrow><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><mrow><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mi>p</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math> is the momentum transfer. A two-dimensional ( <italic>M</italic> <inf>&#923;<italic>p</italic></inf>, <italic>q</italic>) fit demonstrates that the enhancement near the threshold is statistically significant, yielding a local significance of 7.3&#8201; <italic>&#963;</italic>. The enhancement is characterized by effective shape parameters including the Breit&#8211;Wigner mass <italic>M</italic> and width &#915;, and a Gaussian form-factor momentum scale <italic>Q</italic>: <math altimg='si32.svg'><mrow><mi>M</mi><mo linebreak='goodbreak'>=</mo><mn>2.354</mn><mo>&#177;</mo><mn>0.011</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.005</mn></mrow><mrow><mo>+</mo><mn>0.009</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math>, <math altimg='si33.svg'><mrow><mstyle mathvariant='normal'><mi>&#915;</mi></mstyle><mo linebreak='goodbreak'>=</mo><mn>0.055</mn><mo>&#177;</mo><mn>0.023</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.009</mn></mrow><mrow><mo>+</mo><mn>0.031</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math>, and <math altimg='si34.svg'><mrow><mi>Q</mi><mo linebreak='goodbreak'>=</mo><mn>0.350</mn><mo>&#177;</mo><mn>0.041</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.010</mn></mrow><mrow><mo>+</mo><mn>0.035</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><mi>c</mi></mrow></math>. The obtained results support the existence of a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state in photoproduction.

Japan

R. Kobayakawa

South Korea

J.K. Ahn

S. Ajimura

Taiwan

W.C. Chang

M.L. Chu

S. Daté

T. Gogami

T.A. Hashimoto

T. Hotta

T. Ishikawa

H. Katsuragawa

H. Kohri

Y. Ma

M. Miyabe

K. Mizutani

China

N. Muramatsu

T. Nakano

Vietnam

T.H. Nam

M. Niiyama

Y. Nozawa

Y. Ohashi

H. Ohkuma

H. Ohnishi

T. Ohta

Canada

C. Rangacharyulu

S.Y. Ryu

Y. Sada

H. Shimizu

M. Sumihama

S. Suzuki

S. Tanaka

A.O. Tokiyasu

N. Tomida

K. Watanabe

T. Yorita

C. Yoshida

M. Yosoi

Evidence for a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state in the <italic>&#947;d</italic>&#8239;&#8594;&#8239; <italic>K</italic> 0&#923; <italic>p</italic> reaction

This paper presents a study of the charmless three-body decays $$ {B}_{(s)}^0\to {K}_{\mathrm{S}}^0{h}^{+}h{\prime}^{-} $$ (where $\textit{h}$ $\textit{′}$ = $\textit{π, K}$), using a sample of $\textit{pp}$ collision data collected by the LHCb experiment during Runs 1 and 2 of the LHC, corresponding to an integrated luminosity of 9 fb . The decay $$ {B}_s^0\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $$ is observed for the first time, and the following ratios of branching fractions are measured:

Netherlands

R. Aaij

United Kingdom

A. Abdelmotteleb

Switzerland

C. Abellan Beteta

F. Abudinén

T. Ackernley

United States

A. Adefisoye

Spain

B. Adeva

M. Adinolfi

Sweden

P. Adlarson

France

H. Afsharnia

C. Agapopoulou

C. Aidala

Z. Ajaltouni

S. Akar

K. Akiba

Italy

P. Albicocco

Germany

J. Albrecht

F. Alessio

Z. Aliouche

P. Alvarez Cartelle

R. Amalric

Brazil

S. Amato

J. Amey

Y. Amhis

L. An

L. Anderlini

M. Andersson

A. Andreianov

P. Andreola

M. Andreotti

D. Andreou

A. Anelli

D. Ao

F. Archilli

M. Argenton

Costa Rica

S. Arguedas Cuendis

A. Artamonov

M. Artuso

E. Aslanides

R. Ataíde Da Silva

M. Atzeni

B. Audurier

D. Bacher

I. Bachiller Perea

S. Bachmann

M. Bachmayer

J. Back

P. Baladron Rodriguez

V. Balagura

W. Baldini

L. Balzani

H. Bao

J. Baptista de Souza Leite

C. Barbero Pretel

M. Barbetti

I. Barbosa

R. Barlow

M. Barnyakov

S. Barsuk

W. Barter

M. Bartolini

J. Bartz

J. Basels

Poland

S. Bashir

G. Bassi

B. Batsukh

P. Battista

A. Bay

A. Beck

M. Becker

F. Bedeschi

I. Bediaga

N. Behling

S. Belin

V. Bellee

K. Belous

I. Belov

I. Belyaev

E. Ben-Haim

G. Benane

G. Bencivenni

A. Berezhnoy

R. Bernet

S. Bernet Andres

E. Bertholet

A. Bertolin

C. Betancourt

F. Betti

J. Bex

Ia. Bezshyiko

J. Bhom

M. Bieker

N. Biesuz

P. Billoir

A. Biolchini

M. Birch

F. Bishop

A. Bitadze

A. Bizzeti

T. Blake

Improved branching-fraction measurements of $$ {B}_{(s)}^0\to {K}_{\mathrm{S}}^0{h}^{+}h{\prime}^{-} $$ decays and first observation of $$ {B}_s^0\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $$

An analysis of the <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>K</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo stretchy="false">(</mo><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><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> decay is presented using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>8.4</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. The full set of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-averaged and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-asymmetric angular observables is determined in bins of the invariant mass squared of the dimuon system, as well as the branching fraction relative to the <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><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><mo stretchy="false">(</mo><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><mo stretchy="false">)</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> decay. For the first time, the full set of observables pertaining to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> S-wave contribution to the final state are presented and consideration is given to effects arising from the mass of the muons. The extracted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-asymmetry observables show no significant deviations from zero. The measurements of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-averaged observables and the branching fractions continue to exhibit the pattern of tensions with the standard model predictions that have been seen in previous analyses that use part of the dataset considered in this Letter.

A.S.W. Abdelmotteleb

A.A. Adefisoye

C.A. Aidala

M. Akthar

R. Aleksiejunas

CERN

J.L. Amey

S. Andres Estrada

C. Arata

Z. Areg

L. Arnone

J.A. Authier

J.J. Back

A. Balboni

Z. Baldwin

I.R. Barbosa

R.J. Barlow

P.B. Battista

I.B. Bediaga

N.A. Behling

A. Bellavista

O. Bezshyyko

S. Bhattacharya

M.S. Bieker

N.V. Biesuz

F.C.R. Bishop

Comprehensive Analysis of the <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>K</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> Decay

In contrast to potential-driven warm inflation models, this paper presents a new inflationary scenario driven purely by noncanonical kinetic terms. We derive the evolution equations and the associated slow-roll approximations specific to the kinetic case. The model incorporates a nonminimal derivative coupling that enhances gravitational friction; when combined with thermal damping, this leads to a significantly slower evolution of the pure kinetic inflaton. The resulting slow-roll approximations differ fundamentally from those of potential-driven inflation. The attractor behavior of this warm $\textit{k}$-inflation with nonminimal derivative coupling is explored, confirming that slow-roll solutions can approach a strict exponential expansion attractor under relaxed slow-roll conditions. We further calculate the density fluctuation equations and obtain analytic expressions for the power spectrum, spectral index, and tensor-to-scalar ratio. Compared to standard inflation in general relativity, the energy scale at horizon crossing is lower, and the tensor-to-scalar ratio is significantly reduced due to the combined effects of thermal damping and nonminimal derivative coupling. The field excursion remains comfortably sub-Planckian. The model’s predictions are in excellent agreement with the latest Planck 2018 data, offering a novel and successful extension of the warm inflation paradigm.

Xiao-Min Zhang

Zi-Xin Bai

Run-Qing Zhao

Peng-Cheng Chu

Yun-Cai Feng

Zhi-Peng Peng

Xi-Bin Li

Dynamics of potential-free warm $$\textbf{k}$$ -inflation with nonminimal derivative coupling

Based on a novel method for producing antineutrons via <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> decays, we report a study of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover><mi>p</mi></math> inelastic scattering into final states containing kaons. The analysis uses <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>10</mn><mtext> </mtext><mn>087</mn><mo>±</mo><mn>44</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>6</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> events collected at the BESIII detector operating at the BEPCII storage ring. Antineutrons are produced via <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><mi>p</mi><msup><mi>π</mi><mo>−</mo></msup><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover></math> decays and tagged by the detected protons and pions, resulting in antineutron momenta ranging from 0 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1174</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><mi>c</mi></mrow></math>, while target protons are provided by the hydrogen in the beam-pipe material. The flux-averaged cross sections of the reactions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover><mi>p</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover><mi>p</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math> over this antineutron momentum spectrum are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mn>0.53</mn><mrow><mo>−</mo><mn>0.12</mn></mrow><mrow><mo>+</mo><mn>0.15</mn></mrow></msubsup><mo>±</mo><mn>0.08</mn><mtext> </mtext><mtext> </mtext><mi>mb</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mn>1.09</mn><mrow><mo>−</mo><mn>0.30</mn></mrow><mrow><mo>+</mo><mn>0.36</mn></mrow></msubsup><mo>±</mo><mn>0.31</mn><mtext> </mtext><mtext> </mtext><mi>mb</mi></math>, respectively, where the first uncertainties are statistical and the second are systematic. Due to limited statistics, the contributions of intermediate states remain speculative. The observation of clean antineutron-proton scattering candidates indicates the potential of this approach for future investigations of antineutron-proton interactions.

M. Ablikim

Russia

M.N. Achasov

X.C. Ai

Cross-section measurements of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover><mi>p</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><mo stretchy="false">(</mo><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">)</mo></math> via antineutrons produced by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><mi>p</mi><msup><mi>π</mi><mo>−</mo></msup><mover accent="true"><mi>n</mi><mo stretchy="false">¯</mo></mover></math> decays