The production of heavy-quark (HQ) jets is a new area that addresses the mass effect of jet quenching in heavy-ion physics. This paper presents a theoretical study of HQ jet yield suppression in Pb+Pb collisions at the Large Hadron Collider (LHC) and focuses on the energy loss of HQ jets produced by different mechanisms. The $\textit{p+p}$ baseline is provided by the generator simulation of high-energy reactions of particles (SHERPA), and the jet-medium interactions are described by the SHELL transport model, which considers the elastic and inelastic partonic energy loss in the quark-gluon plasma (QGP). In $\textit{p+p}$ collisions, our numerical results indicate that the HQ jets from gluon splitting ( $ g \rightarrow Q $ -jet) are the dominant contribution at high $ p_T $ , displaying more dispersive structures than the HQ-initiated ( $ Q \rightarrow Q $ -jet). In nucleus-nucleus collisions, our calculations were consistent with the inclusive and b-jet $ R_{AA} $ recently measured by the ATLAS collaboration, revealing a remarkable manifestation of the mass effect of jet energy loss. As a result of the dispersive substructure, the $ g \rightarrow Q $ -jet loses more energy than the $ Q \rightarrow Q $ -jet in the QGP. Due to the significant contribution of $ g \rightarrow c $ -jet, the $ R_{AA} $ of $\textit{c}$-jet is comparable or even smaller than that of inclusive jet. To experimentally distinguish the $ g \rightarrow Q $ -jet and $ Q \rightarrow Q $ -jet, we propose event selection strategies based on their topological features and test their performances. By isolating the $ c \rightarrow c $ -jet, $ b \rightarrow b $ -jet, and the jets initiated by heavy quarks, we predicted that the order of their $ R_{AA} $ are in line with the mass hierarchy of energy loss. Future measurements on the $ R_{AA} $ of $ Q \rightarrow Q $ -jet and $ g \rightarrow Q $ -jet will provide a unique opportunity for testing the flavor/mass dependence of energy loss at the jet level.

China

Sa Wang

Shuang Li

Yao Li

Ben-Wei Zhang

Enke Wang

Probing the mass effect of heavy quark jets in high-energy nuclear collisions * Supported by the MajorProject of Basic and Applied Basic Research of Guangdong Province, China (2020B0301030008, 2023A1515011460), and the National Natural Science Foundation of China (11935007, 12035007, 12247127, 12375137). Sa Wang is supported by the Open Foundation of Key Laboratory of Quark and Lepton Physics (MOE) (QLPL2023P01) and the Talent Scientific Star-up Foundation of the China Three Gorges University, China (CTGU) (2024RCKJ013)

Detailed studies of two-neutrino double electron capture (2$\textit{ν}$DEC) is a crucial step towards searching for the neutrinoless mode to explore the Majorana nature of neutrinos. We have measured precisely the half-life of the 2$\textit{ν}$DEC process in Xe, utilizing a total exposure of 1.73 tonne year from the commissioning run and the first science run of the PandaX-4T experiment. A time-dependent background model in the $$ \mathcal{O} $$ (10 keV) energy is constructed for the first time in PandaX-4T data. With an unbinned maximum likelihood fit, we determine the half-life of the 2$\textit{ν}$DEC process to be (1.03 ± 0.15 ± 0.08 ) × 10 yr. Furthermore, we have evaluated the capture fraction for both electrons captured from the $\textit{K}$ shell ($\textit{KK}$) to be (65 ± 5)%, which aligns with the Xe nuclear model calculations within 1.8 $\textit{σ}$.

Zihao Bo

Wei Chen

Xun Chen

Yunhua Chen

Zhaokan Cheng

Xiangyi Cui

Yingjie Fan

Deqing Fang

Zhixing Gao

Lisheng Geng

Karl Giboni

Xunan Guo

Xuyuan Guo

Zichao Guo

Chencheng Han

Ke Han

Changda He

Jinrong He

Di Huang

Houqi Huang

Junting Huang

Ruquan Hou

Yu Hou

United States

Xiangdong Ji

Xiangpan Ji

Yonglin Ju

Chenxiang Li

Jiafu Li

Mingchuan Li

Shuaijie Li

Tao Li

Zhiyuan Li

Qing Lin

Jianglai Liu

Congcong Lu

Xiaoying Lu

Lingyin Luo

Yunyang Luo

Wenbo Ma

Yugang Ma

Yajun Mao

Yue Meng

Xuyang Ning

Binyu Pang

Ningchun Qi

Zhicheng Qian

Xiangxiang Ren

Dong Shan

Xiaofeng Shang

Xiyuan Shao

Guofang Shen

Manbin Shen

Wenliang Sun

Yi Tao

Anqing Wang

Guanbo Wang

Hao Wang

Jiamin Wang

Lei Wang

Meng Wang

Qiuhong Wang

Shaobo Wang

Siguang Wang

Wei Wang

Xiuli Wang

Xu Wang

Zhou Wang

Yuehuan Wei

Weihao Wu

Yuan Wu

Mengjiao Xiao

Xiang Xiao

Kaizhi Xiong

Yifan Xu

Shunyu Yao

Binbin Yan

Xiyu Yan

Yong Yang

Peihua Ye

Chunxu Yu

Ying Yuan

Zhe Yuan

Youhui Yun

Xinning Zeng

Minzhen Zhang

Peng Zhang

Shibo Zhang

Shu Zhang

Tao Zhang

Wei Zhang

Yang Zhang

Yingxin Zhang

Yuanyuan Zhang

Li Zhao

Jifang Zhou

Jiaxu Zhou

Jiayi Zhou

Ning Zhou

Xiaopeng Zhou

Yubo Zhou

Measurement of two-neutrino double electron capture half-life of

<p>Using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>2712.4</mn><mo>±</mo><mn>14.3</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo></mrow></math> events collected with the BESIII detector at BEPCII, a partial wave analysis of the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ϕ</mi><mi>η</mi><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></math> is performed with the covariant tensor approach. In addition to the established states <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1900</mn></math>) and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo></math>, an axial-vector state with a mass near <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2.3</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math> is observed for the first time. Its mass and width are measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2316</mn><mo>±</mo><msub><mrow><mn>9</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>3</mn><msub><mrow><mn>0</mn></mrow><mrow><mi>syst</mi></mrow></msub><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"><mrow><mn>89</mn><mo>±</mo><mn>1</mn><msub><mrow><mn>5</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>2</mn><msub><mrow><mn>6</mn></mrow><mrow><mi>syst</mi></mrow></msub><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>, respectively. The product branching fractions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>X</mi><mo stretchy="false">(</mo><mn>2300</mn><mo stretchy="false">)</mo><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">]</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi>X</mi><mo stretchy="false">(</mo><mn>2300</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ϕ</mi><mi>η</mi><mo stretchy="false">]</mo></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>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>X</mi><mo stretchy="false">(</mo><mn>2300</mn><mo stretchy="false">)</mo><mi>η</mi><mo stretchy="false">]</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi>X</mi><mo stretchy="false">(</mo><mn>2300</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">]</mo></mrow></math> are determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>4.8</mn><mo>±</mo><msub><mrow><mn>1.3</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><msub><mrow><mn>0.7</mn></mrow><mrow><mi>syst</mi></mrow></msub><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><mo stretchy="false">(</mo><mn>2.2</mn><mo>±</mo><msub><mrow><mn>0.7</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><msub><mrow><mn>0.7</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math>, respectively. The branching fraction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ϕ</mi><mi>η</mi><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">]</mo></mrow></math> is measured for the first time to be (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.14</mn><mo>±</mo><mn>0.1</mn><msub><mrow><mn>7</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.2</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>5</mn></mrow></msup></mrow></math>. The first uncertainties are statistical and the second are systematic.</p>

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

R.A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

J.F. Chang

W.L. Chang

G.R. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

Z.Y. Chen

South Korea

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Z.H. Duan

P. Egorov

Y.H. Fan

J. Fang

Observation of an Axial-Vector State in the Study of the Decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3686</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ϕ</mi><mi>η</mi><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></math>