The response of liquid xenon to various types of ionizing radiation has been extensively studied theoretically and experimentally. Recent progress in direct detection dark matter experiments highlights the significance of composite events, where multiple particles interact with xenon simultaneously and generate overlapping ionization signatures. In these events, recombination of electrons and ions associated with different primary particles leads to additional suppression of the ionization signal, introducing a new source of uncertainty in dark matter searches and Migdal effect studies. We developed a model to estimate the recombination enhancement for overlapping low-energy particle interactions. This method, which has minimal dependence on xenon microphysics and is primarily driven by existing experimental data, yields predictions that are consistent with available measurements of composite interactions. Furthermore, we demonstrate that the model predictions are robust against xenon microphysics assumptions.

United States

J. Xu

J. Kim

B. Lenardo

C.E. Dahl

R.L. Mannino

G.M. Blockinger

C.A. Hardy

D. Adams

C.S. Amarasinghe

J. Bang

A.C. Vaitkus

C. Ding

W.H. Lippincott

M. Szydagis

C. Levy

R.J. Gaitskell

R. Essig

Electron-ion recombination in composite interactions in liquid xenon

We propose a new mechanism of generating spin polarization in heavy-ion collisions dominated by nucleon degree of freedom. By incorporating the spin change in nucleon-nucleon scatterings based on the phase shift data together with the constraint of rigorous angular momentum conservation and Pauli blocking, we illustrate through a Boltzmann-Uehling-Uhlenbeck transport model that appreciable spin polarization (about <math altimg='si1.svg'><mn>1</mn><mo>&#8764;</mo><mn>2</mn><mtext>%</mtext></math>) can be generated in intermediate-energy heavy-ion collisions. This mechanism, together with the nuclear spin-orbit potential, may help to understand the spin polarization in few-GeV heavy-ion collisions dominated by nucleon degree of freedom.

China

Rong-Jun Liu

Jun Xu

Yu-Gang Ma

Spin polarization from nucleon-nucleon scatterings in intermediate-energy heavy-ion collisions

We study the production of open-flavor heavy hadrons in relativistic heavy-ion collisions. The hadronization in the quark-gluon plasma is described in the quark coalescence model. We evaluated yields and transverse momentum distributions. A simultaneous study of conventional and exotic hadrons is carried out. The Wigner functions are evaluated using hadron wave functions obtained from a single realistic quark model. Thus, results are presented in a single framework for the production of open-flavor heavy mesons, baryons, and exotic tetraquarks, in particular: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Λ</mi><mi>Q</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Σ</mi><mi>Q</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>Q</mi></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup></mrow></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup></mrow></msub></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi><mo>,</mo><msup><mi>Q</mi><mo>′</mo></msup><mo>=</mo><mi>c</mi></math> or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>). The consequences of a partial restoration of chiral symmetry at the hadronization temperature are studied in detail.

Brazil

C.E. Fontoura

G. Krein

Spain

A. Valcarce

J. Vijande

Open-flavor heavy hadron production in heavy-ion collisions

The cross sections for the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><mi>η</mi></mrow></math> reaction are evaluated at energies relevant for the HADES, PANDA, and SIS100 experiments at GSI-FAIR (Facility for Antiproton and Ion Research). Consideration includes the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math>-bremsstrahlung mechanism involving intermediate proton exchange via the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>π</mi><mn>0</mn></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ω</mi></math> exchanges and the mechanism involving the nucleon resonances <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1650</mn><mo>)</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1710</mn><mo>)</mo></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1880</mn><mo>)</mo></mrow></math> excited via the pseudoscalar- and/or vector-meson exchanges, depending on the model. The role of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ω</mi><mi>ω</mi></mrow></math>- and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>ρ</mi><mn>0</mn></msup><msup><mi>ρ</mi><mn>0</mn></msup></mrow></math>-fusion processes with the Reggeized vector-meson exchanges is also discussed. The calculation is done in an effective Lagrangian approach. To determine the parameters of the model, the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>γ</mi><mi>p</mi><mo>→</mo><mi>η</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>π</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>η</mi><mi>n</mi></mrow></math> reactions are studied and the results are then compared with the Crystal Ball and CLAS data. For the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>p</mi><mi>p</mi><mi>η</mi></mrow></math> reaction, the model results are compared with the energy dependence of the cross section measured far from the threshold and with the differential distributions <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>d</mi><mi>σ</mi><mo>/</mo><mi>d</mi><mo form="prefix">cos</mo><msub><mi>θ</mi><mi>η</mi></msub></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>d</mi><mi>σ</mi><mo>/</mo><mi>d</mi><msub><mi>p</mi><mi>η</mi></msub></mrow></math> measured by the DISTO Collaboration. The comparison shows that the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></mrow></math> resonance is the dominant contribution and that other contributions are also important due to interference effects. Assuming that the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ρ</mi></math> exchange is the dominant resonant excitation process, the model is able to describe the available data, e.g., it reproduces the shape of the angular distributions measured by the DISTO Collaboration. Predictions are given for the HADES experiment at center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>3.46</mn></mrow></math> GeV, which can be verified in the near future, and for planned PANDA and SIS100 experiments at higher energies.

Piotr Lebiedowicz

Exclusive <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>η</mi></math> production in proton-proton collisions at energies available at the GSI Facility for Antiproton and Ion Research

A loosely bound hadronic molecule produced by a relativistic heavy-ion collision has been described as a “snowball in hell” since it emerges from a hadron resonance gas whose temperature is orders of magnitude larger than the binding energy of the molecule. This remarkable phenomenon can be explained in terms of a novel thermodynamic variable called the “contact” that is conjugate to the binding momentum of the molecule. The production rate of the molecule can be expressed in terms of the contact density at the kinetic freeze-out of the hadron resonance gas. It approaches a nonzero limit as the binding energy goes to 0.

Eric Braaten

Kevin Ingles

Justin Pickett

Explaining Snowball-in-Hell Phenomena in Heavy-Ion Collisions Using a Novel Thermodynamic Variable

We present the design and performance of a four-phased radiofrequency (RF) carpet system for ion transport between 200–600 mbar, significantly higher than previously demonstrated RF carpet applications. The RF carpet, designed with a 160 $$\upmu $$ m pitch, is applied to the lateral collection of ions in xenon at pressures up to 600 mbar. We demonstrate transport efficiency of caesium ions across varying pressures, and compare with microscopic simulations made in the SIMION package. The novel use of an N-phased RF carpet can achieve ion levitation and controlled lateral motion in a denser environment than is typical for RF ion transport in gases. This feature makes such carpets strong candidates for ion transport to single ion sensors envisaged for future neutrinoless double-beta decay experiments in xenon gas.

E. Dey

B. Jones

Y. Mei

M. Brodeur

V. Chirayath

N. Coward

F. Foss

K. Navarro

I. Parmaksiz

C. Adams

United Kingdom

H. Almazán

V. Álvarez

B. Aparicio

A. Aranburu

Israel

L. Arazi

I. Arnquist

F. Auria-Luna

S. Ayet

Portugal

C. Azevedo

K. Bailey

F. Ballester

M. Barrio-Torregrosa

A. Bayo

J. Benlloch-Rodríguez

F. Borges

A. Brodolin

N. Byrnes

S. Cárcel

A. Castillo

E. Church

L. Cid

C. Conde

T. Contreras

F. Cossío

R. Coupe

G. Díaz

C. Echevarria

M. Elorza

J. Escada

R. Esteve

R. Felkai

L. Fernandes

P. Ferrario

A. Ferreira

Z. Freixa

J. García-Barrena

J. Gómez-Cadenas

J. Grocott

R. Guenette

J. Hauptman

C. Henriques

J. Morata

P. Herrero-Gómez

V. Herrero

C. Carrete

Y. Ifergan

F. Kellerer

L. Larizgoitia

A. Larumbe

P. Lebrun

F. Lopez

N. López-March

R. Madigan

R. Mano

A. Marques

J. Martín-Albo

G. Martínez-Lema

M. Martínez-Vara

R. Miller

K. Mistry

J. Molina-Canteras

F. Monrabal

C. Monteiro

F. Mora

P. Novella

A. Nuñez

D. Nygren

E. Oblak

J. Palacio

B. Palmeiro

A. Para

A. Pazos

J. Pelegrin

M. Maneiro

M. Querol

J. Renner

I. Rivilla

C. Rogero

L. Rogers

B. Romeo

C. Romo-Luque

V. Nacienciano

F. Santos

J. Santos

M. Seemann

I. Shomroni

P. Silva

A. Simón

S. Soleti

M. Sorel

Ion transport on phased radiofrequency carpets in xenon gas

Measurements of $$ b\to {c\tau}^{-}{\overline{\nu}}_{\tau } $$ transitions at colliders are highly motivated for testing lepton flavor universality (LFU), a cornerstone hypothesis of the Standard Model (SM). Potential observations of LFU violation could provide significant evidence for physics beyond the SM (BSM). The substantial production of $\textit{b}$-hadrons at the Electron-Ion Collider (EIC) would highlight its potential to support LFU testing and complement studies conducted at other experimental facilities. In this paper, we study the production of $\textit{b}$-hadrons in deep inelastic scattering processes at the EIC with $$ \sqrt{s} $$ = 100 GeV. We estimate the $\textit{b}$-hadron yields at the EIC to reach $$ \mathcal{O}\left({10}^9\right) $$ with an integrated luminosity of up to 10 fb . Furthermore, we perform a systematic study on various $\textit{b}$-hadron decays, exploring the sensitivities of LFU-violating observables, including $\textit{R}$ , $$ {R}_{D_s^{\left(\ast \right)}} $$ and $$ {R}_{\Lambda_c} $$ . Detailed strategies for track-based event reconstruction are investigated for these observables. We also include a discussion of the annihilation process $$ {B}_c^{+}\to {\tau}^{+}{\nu}_{\tau } $$ . Finally, we provide a theoretical interpretation of the projected sensitivities within the framework of low energy effective field theory (LEFT). Our analysis indicates that the EIC has the potential to constrain the relevant Wilson coefficients at $$ \mathcal{O}(0.1) $$ , offering complementary insights to other measurements.

Yong Deng

Xu-Hui Jiang

Tianbo Liu

Bin Yan

Testing lepton flavor universality at the Electron-Ion Collider

We present a factorization formula for the energy-energy correlator in the collinear limit for the case of heavy ion collisions. Employing Soft Collinear Effective Theory, we provide a complete framework for jet production and evolution by separating the jet dynamics from the universal medium physics to all orders in perturbation theory in terms of gauge invariant operators. The EFT allows us to precisely define the domain of validity of different approximations and to systematically go beyond leading order results in the literature through radiative corrections. For this observable, we show where the leading order GLV and BDMPS-Z results are valid and infer that higher order radiative corrections lead to both DGLAP and BFKL evolutions. We further show the impact of BFKL resummation on the medium induced jet function for two point energy correlator. Crucially, the EFT approach enables us to evaluate the universality of the non-perturbative physics which is the key to predictive power in a strongly coupled medium.

Balbeer Singh

Varun Vaidya

Factorization for energy-energy correlator in heavy ion collision

The Electron-Ion Collider in China (EicC), a proposed high-luminosity facility with advanced charged particle and photon detection capabilities, provides unique opportunities to uncover new physics beyond the Standard Model. We analyze its sensitivity to dark photons produced through electron bremsstrahlung in coherent scattering. Thanks to its beam energy settings, it has the potential to comprehensively probe the previously unexplored parameter space between the constraints from meson decays and beam dumps below $$ \mathcal{O}(1) $$ GeV with displaced-vertex search. Additionally, the EicC has the potential to probe axion-like particles (ALPs) in the mass range 0$\textit{.}$1 GeV ≲ $\textit{m}$ ≲ 5 GeV, with a coupling reach of Λ ≲ 10 GeV, by combining the prompt-decay and displaced-vertex searches. The projected sensitivities to ALPs exceed the current bounds.

Qiyuan Gao

Dan Lin

Hongkai Liu

Teng Ma

Dark photons and axion-like particles at the electron-ion collider in China

We employ an equal-velocity quark combination model to study anisotropic flows <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub><mo>,</mo><mo> </mo><msub><mi>v</mi><mn>3</mn></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>4</mn></msub></math> of identified hadrons at midrapidity in heavy-ion collisions at Relativistic Heavy Ion Collider energies. Under the equal-velocity combination mechanism of constituent quarks at hadronization, we build analytical formulas of anisotropic flows of hadrons in terms of those of quarks just before hadronization. We systematically analyze the contribution of higher-order flows of quarks, and show how simple formulas of <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub><mo>,</mo><mo> </mo><msub><mi>v</mi><mn>3</mn></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>4</mn></msub></math> of identified hadrons with the desired precision can be obtained by neglecting the small contribution of higher-order flows of quarks. We systematically test these simple formulas of hadronic flows by the experimental data of <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub><mo>,</mo><mo> </mo><msub><mi>v</mi><mn>3</mn></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>4</mn></msub></math> of identified hadrons <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ϕ</mi><mo>,</mo><mo> </mo><mi mathvariant="normal">Λ</mi><mo>,</mo><mo> </mo><msup><mi mathvariant="normal">Ξ</mi><mo>−</mo></msup><mo>,</mo><mo> </mo><msup><mi mathvariant="normal">Ω</mi><mo>−</mo></msup><mo>,</mo><mo> </mo><mover accent="true"><mi mathvariant="normal">Λ</mi><mo>¯</mo></mover><mo>,</mo><mo> </mo><msup><mover accent="true"><mi mathvariant="normal">Ξ</mi><mo>¯</mo></mover><mo>+</mo></msup><mo>,</mo><mo> </mo><msup><mover accent="true"><mi mathvariant="normal">Ω</mi><mo>¯</mo></mover><mo>+</mo></msup><mo>,</mo><mo> </mo><mi>p</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent="true"><mi>p</mi><mo>¯</mo></mover></math> in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>19.6</mn></mrow></math>, 54.4, and 200 GeV, and we find that the equal-velocity quark combination model can well describe the measured <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub><mo>,</mo><mo> </mo><msub><mi>v</mi><mn>3</mn></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>4</mn></msub></math> of identified hadrons in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at those collision energies. We further study the obtained anisotropic flows of quarks and find two scaling properties which can be qualitatively understood by the hydrodynamic evolution of the thermal quark medium produced in relativistic heavy-ion collisions.

Yan-ting Feng

Rui-qin Wang

Feng-lan Shao

Jun Song

Anisotropic flows of identified hadrons in the equal-velocity quark combination model at energies available at the BNL Relativistic Heavy Ion Collider