<p>Utilizing the 2012 transversely polarized proton data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, the forward <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi></math>-meson transverse single-spin asymmetry (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mi>N</mi></msub></math>) was measured for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>p</mi></mrow><mrow><mo stretchy="false">↑</mo></mrow></msup><mo>+</mo><mi>p</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> as a function of Feynman-x (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>x</mi><mi>F</mi></msub></math>) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.2</mn><mo>&lt;</mo><mo stretchy="false">|</mo><msub><mi>x</mi><mi>F</mi></msub><mo stretchy="false">|</mo><mo>&lt;</mo><mn>0.8</mn></math> and transverse momentum (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub></math>) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.0</mn><mo>&lt;</mo><msub><mi>p</mi><mi>T</mi></msub><mo>&lt;</mo><mn>5.0</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><mi>c</mi></math>. Large asymmetries at positive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>x</mi><mi>F</mi></msub></math> are observed (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mo stretchy="false">⟨</mo><msub><mrow><mi>A</mi></mrow><mrow><mi>N</mi></mrow></msub><mo stretchy="false">⟩</mo></mrow><mo>=</mo><mn>0.086</mn><mo>±</mo><mn>0.019</mn></mrow></math>), agreeing well with previous measurements of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mn>0</mn></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>η</mi><mtext> </mtext><msub><mrow><mi>A</mi></mrow><mrow><mi>N</mi></mrow></msub></mrow></math>, but with reach to higher <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>x</mi><mi>F</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub></math>. The contribution of initial-state spin-momentum correlations to the asymmetry, as calculated in the collinear twist-3 framework, appears insufficient to describe the data.</p>

N.J. Abdulameer

U. Acharya

C. Aidala

N.N. Ajitanand

Y. Akiba

R. Akimoto

J. Alexander

D. Anderson

S. Antsupov

K. Aoki

N. Apadula

H. Asano

E.T. Atomssa

T.C. Awes

B. Azmoun

V. Babintsev

M. Bai

X. Bai

B. Bannier

E. Bannikov

K.N. Barish

S. Bathe

V. Baublis

C. Baumann

S. Baumgart

A. Bazilevsky

M. Beaumier

R. Belmont

A. Berdnikov

Y. Berdnikov

L. Bichon

D. Black

B. Blankenship

D.S. Blau

J.S. Bok

V. Borisov

K. Boyle

M.L. Brooks

J. Bryslawskyj

H. Buesching

V. Bumazhnov

S. Butsyk

S. Campbell

P. Chaitanya

C.H. Chen

D. Chen

M. Chiu

C.Y. Chi

I.J. Choi

J.B. Choi

S. Choi

P. Christiansen

T. Chujo

V. Cianciolo

B.A. Cole

M. Connors

R. Corliss

N. Cronin

N. Crossette

M. Csanád

T. Csörgő

L. D’Orazio

A. Datta

M.S. Daugherity

G. David

K. Dehmelt

A. Denisov

A. Deshpande

E.J. Desmond

L. Ding

V. Doomra

J.H. Do

O. Drapier

A. Drees

K.A. Drees

J.M. Durham

A. Durum

T. Engelmore

A. Enokizono

R. Esha

K.O. Eyser

B. Fadem

D.E. Fields

M. Finger

D. Firak

D. Fitzgerald

F. Fleuret

S.L. Fokin

J.E. Frantz

A. Franz

A.D. Frawley

Y. Fukao

T. Fusayasu

K. Gainey

C. Gal

P. Garg

A. Garishvili

I. Garishvili

F. Giordano

Transverse single-spin asymmetry of forward <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi></math> mesons in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>p</mi></mrow><mrow><mo stretchy="false">↑</mo></mrow></msup><mo>+</mo><mi>p</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>

The weak decays of the $$D_{(s)}$$ meson provide a pivotal platform to advance our understanding of the Standard Model (SM) and to explore New Physics (NP). In recent years, experiments have collected a significant amount of data on the $$D_{(s)}$$ meson decays, particularly from BESIII, which provides substantial support for theoretical research. In this work, we systematically investigate the semi-leptonic decays of $$D_{(s)}$$ meson to pseudoscalar (P), scalar (S), vector (V), and axial-vector (A) mesons within the framework of the covariant light-front quark model (CLFQM). We calculate the form factors of the transitions $$D_{(s)}\rightarrow P,S,V,A$$ and the branching ratios of the corresponding semi-leptonic decays, then compare them with experimental data and results from other theoretical models. The form factor values of the transitions $$D_{(s)}\rightarrow P, V$$ obtained from the CLFQM are consistent with those of other theoretical models and available data in most cases. However, significant discrepancies are found in some specific $$D_{(s)}\rightarrow S,A$$ transitions, such as $$D\rightarrow a_0(980), a_0(1450)$$ and $$D_{(s)} \rightarrow K_{1B}$$ , compared to other theoretical calculations. The predicted branching ratios for the semi-leptonic decays $$D\rightarrow P(V)\ell \nu _\ell $$ with $$\ell =e,\mu $$ agree well with experimental data and other theoretical results in most decay channels, validating the reliability of the model. However, for some $$D\rightarrow S(V)\ell \nu _\ell $$ decays, tension exists among different theoretical predictions and experimental results. Further clarification of such differences is necessary. Our study provides important insights into the internal structures for some scalar and axial-vector mesons and serves as a theoretical reference for future experiments.

China

Hao Yang

Shao-Qin Guo

Zhi-Qing Zhang

Systematic analysis of $$D_{(s)}$$ meson semi-leptonic decays in the covariant light-front quark model

<p>The first four-dimensional amplitude analysis of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msubsup><mi>K</mi><mi mathvariant="normal">S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mo>+</mo></msup></math> decay is performed with proton-proton collision data collected by the LHCb experiment at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.4</mn><mtext> </mtext><mtext> </mtext><mrow><mi mathvariant="normal">f</mi><msup><mrow><mi mathvariant="normal">b</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></mrow></math>. The data cannot be fully explained by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msup><mi>K</mi><mrow><mo>*</mo><mo>+</mo></mrow></msup></math> contributions alone. A significantly better description of the data is obtained by adding a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></mrow><mo>+</mo></msubsup></math> contribution decaying to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msup><mi>π</mi><mo>+</mo></msup></math>. The properties of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></mrow><mo>+</mo></msubsup></math> structure are consistent with the exotic state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>4430</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup></math> reported in the isospin-related <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup><mo stretchy="false">→</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup></math> decay. Effects of a possible <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>4430</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup><mo stretchy="false">→</mo><msubsup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mn>1</mn><mo>*</mo></msubsup><mo stretchy="false">(</mo><mn>2600</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup><msup><mi>D</mi><mo>+</mo></msup></math> decay mode on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>4430</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msup><mi>π</mi><mo>+</mo></msup></math> mass distribution are investigated through a Flatté parametrization, providing constraints on the relative decay strength. A description of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>4430</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup></math> structure using the triangle singularity mechanism is studied and also found to be consistent with the data.</p>

R. Aaij

A.S.W. Abdelmotteleb

C. Abellan Beteta

F. Abudinén

T. Ackernley

A.A. Adefisoye

B. Adeva

M. Adinolfi

P. Adlarson

C. Agapopoulou

C.A. Aidala

Z. Ajaltouni

S. Akar

K. Akiba

M. Akthar

P. Albicocco

J. Albrecht

R. Aleksiejunas

F. Alessio

P. Alvarez Cartelle

R. Amalric

S. Amato

J.L. Amey

Y. Amhis

L. An

L. Anderlini

M. Andersson

P. Andreola

M. Andreotti

S. Andres Estrada

A. Anelli

D. Ao

C. Arata

F. Archilli

Z. Areg

M. Argenton

S. Arguedas Cuendis

L. Arnone

A. Artamonov

M. Artuso

E. Aslanides

R. Ataíde Da Silva

M. Atzeni

B. Audurier

J.A. Authier

D. Bacher

I. Bachiller Perea

S. Bachmann

M. Bachmayer

J.J. Back

P. Baladron Rodriguez

V. Balagura

A. Balboni

W. Baldini

Z. Baldwin

L. Balzani

H. Bao

J. Baptista de Souza Leite

C. Barbero Pretel

M. Barbetti

I.R. Barbosa

R.J. Barlow

M. Barnyakov

S. Barsuk

W. Barter

J. Bartz

S. Bashir

B. Batsukh

P.B. Battista

A. Bay

A. Beck

M. Becker

F. Bedeschi

I.B. Bediaga

N.A. Behling

S. Belin

A. Bellavista

K. Belous

I. Belov

I. Belyaev

G. Benane

G. Bencivenni

E. Ben-Haim

A. Berezhnoy

R. Bernet

S. Bernet Andres

A. Bertolin

F. Betti

J. Bex

O. Bezshyyko

J. Bhom

M.S. Bieker

N.V. Biesuz

Observation and investigation of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>4430</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup></math> structure in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo><msubsup><mi>K</mi><mi mathvariant="normal">S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mo>+</mo></msup></math> decays