Radiogenic neutrons emitted by detector materials are one of the most challenging backgrounds for the direct search of dark matter in the form of weakly interacting massive particles (WIMPs). To mitigate this background, the XENONnT experiment is equipped with a novel gadolinium-doped water Cherenkov detector, which encloses the xenon dual-phase time projection chamber (TPC). The neutron veto (NV) can tag neutrons via their capture on gadolinium or hydrogen, which release $$\gamma $$ -rays that are subsequently detected as Cherenkov light. In this work, we present the first results of the XENONnT NV when operated with demineralized water only, before the insertion of gadolinium. Its efficiency for detecting neutrons is $$({82\pm 1}){\%}$$ , the highest neutron detection efficiency achieved in a water Cherenkov detector. This enables a high efficiency of $$({53\pm 3}){\%}$$ for the tagging of WIMP-like neutron signals, inside a tagging time window of $${250}~{\upmu }\hbox {s}$$ between TPC and NV, leading to a livetime loss of $${1.6}{\%}$$ during the first science run of XENONnT.

United States

E. Aprile

Netherlands

J. Aalbers

Japan

K. Abe

France

S. Ahmed Maouloud

Germany

L. Althueser

B. Andrieu

Italy

E. Angelino

D. Antón Martin

United Arab Emirates

F. Arneodo

Switzerland

L. Baudis

M. Bazyk

L. Bellagamba

R. Biondi

A. Bismark

K. Boese

A. Brown

G. Bruno

Israel

R. Budnik

China

C. Cai

C. Capelli

Portugal

J. Cardoso

A. Cimental Chávez

A. Colijn

Sweden

J. Conrad

J. Cuenca-García

V. D’Andrea

L. Daniel Garcia

M. Decowski

A. Deisting

C. Di Donato

P. Di Gangi

S. Diglio

K. Eitel

S. el Morabit

A. Elykov

A. Ferella

C. Ferrari

H. Fischer

T. Flehmke

M. Flierman

W. Fulgione

C. Fuselli

P. Gaemers

R. Gaior

M. Galloway

F. Gao

S. Ghosh

R. Giacomobono

R. Glade-Beucke

L. Grandi

J. Grigat

H. Guan

M. Guida

P. Gyorgy

R. Hammann

A. Higuera

C. Hils

L. Hoetzsch

N. Hood

M. Iacovacci

Y. Itow

J. Jakob

F. Joerg

Y. Kaminaga

M. Kara

P. Kavrigin

S. Kazama

M. Kobayashi

D. Koke

A. Kopec

H. Landsman

R. Lang

L. Levinson

I. Li

S. Li

S. Liang

Y.T. Lin

S. Lindemann

M. Lindner

K. Liu

M. Liu

J. Loizeau

F. Lombardi

J. Long

J.A.M. Lopes

T. Luce

Y. Ma

C. Macolino

J. Mahlstedt

A. Mancuso

L. Manenti

F. Marignetti

T. Marrodán Undagoitia

K. Martens

J. Masbou

E. Masson

S. Mastroianni

A. Melchiorre

J. Merz

M. Messina

The neutron veto of the XENONnT experiment: results with demineralized water

We investigate the semileptonic decays of charmed mesons to light vector mesons within the framework of light-cone sum rules. Our calculation is performed at leading order in quantum chromodynamics (QCD) coupling, incorporating contributions up to twist-five accuracy from both two-particle and three-particle light-cone distribution amplitudes. Transition form factors are predicted twist by twist to assess the convergence property of the operator product expansion. It is verified that the twist-four and twist-five contributions are indeed negligible for all the decays under consideration. Twist-three dominance is observed for some of the form factors, subject to heavy quark effective field theory interpretation. Branching ratios for the decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>ρ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo>*</mo><mo>−</mo></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover><mrow><mo>*</mo><mn>0</mn></mrow></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> are obtained, and a 10%–20% discrepancy from experimental measurements is found. Our finding indicates that the resonant-width and nonresonant QCD backgrounds effects should be potentially significant, implying the necessity to further implement their contributions in future precision studies of the semileptonic charm decays.

Wang Lin

Xiao-En Huang

Shan Cheng

De-Liang Yao

Semileptonic decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo stretchy="false">→</mo><mi>ρ</mi><msup><mi>l</mi><mo>+</mo></msup><mi>ν</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mrow><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub><mo stretchy="false">→</mo><msup><mi>K</mi><mo>*</mo></msup><msup><mi>l</mi><mo>+</mo></msup><mi>ν</mi></math> from light-cone sum rules

We present the first lattice result of the near threshold $ \Lambda_c\Lambda_c $ scattering with $ I(J^P) = 0(0^+) $ . The calculation is performed on two $ N_f = 2+1 $ Wilson-Clover ensembles with pion mass $ m_\pi \sim 303 $ MeV and lattice spacing $ a = 0.07746 $ fm. Lüscher's finite volume method is utilized to extract the scattering parameters from the finite-volume spectrum. The coupled channel $ \Xi_{cc}N $ is ignored in the scattering analysis based on the observation that the energy levels computed from the $ \Lambda_c\Lambda_c $ and $ \Xi_{cc}N $ operators do not mix. The $ \Sigma_c\Sigma_c $ channel is not included either since the energy range explored in this study is well below its threshold. Our results indicate that the interaction in the $ \Lambda_c\Lambda_c $ single channel is repulsive, and the scattering length is determined to be $ a_0 = -0.21(4)(8) $ fm, where the first error is statistical and the second is systematic.

Hanyang Xing

Yiqi Geng

Chuan Liu

Liuming Liu

Peng Sun

Jiajun Wu

Zhicheng Yan

Ruilin Zhu

Lattice QCD study of Λ $\textit{c}$ Λ $\textit{c}$ scattering * Supported by NSFC (12293060, 12293061, 12293063, 12175279, 12435002, 12322503, 12175239). L. Liu also acknowledges the Strategic Priority Research Program of the Chinese Academy of Sciences with (XDB34030301) and Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008). We also acknowledge the Science and Education Integration Young Faculty Project of University of Chinese Academy of Sciences (YSBR-101)

We examine the minimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>−</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>τ</mi></mrow></msub></mrow></msub></mrow></math> gauge model in light of the latest neutrino data, including neutrino oscillations, cosmological observations, direct mass measurements, and neutrinoless double-beta decay. Using the most conservative oscillation data, we find that normal ordering is excluded at approximately the 90% confidence level (CL). Incorporating cosmological constraints from cosmic microwave background observations strengthens this exclusion to about 95% CL, while further including baryon acoustic oscillation data increases it to nearly 99% CL. The inverted ordering is even more strongly disfavored. Our analysis is performed within a frequentist framework, minimizing sensitivity to prior assumptions inherent in Bayesian approaches. These results impose strong constraints on the viability of the minimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math> gauge model.

Masahiro Ibe

Satoshi Shirai

Keiichi Watanabe

Global neutrino constraints on the minimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><mo stretchy="false">)</mo></mrow><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>−</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>τ</mi></mrow></msub></mrow></msub></mrow></math> model

We consider the gauged U(1) model and examine the situation where the sterile neutrino is a dark matter candidate produced by the freeze-in mechanism. In our model, the dark matter $\textit{N}$ is mainly produced by the decay of a U(1) breaking scalar boson $\textit{ϕ}$. We point out that the on-shell production of $\textit{ϕ}$ through annihilation of the U(1) gauge boson $\textit{Z}$ plays an important role. We find that the single production of $\textit{Z}$ from the gluon bath in the early Universe can become the main production modes for $\textit{Z}$ in some parameter regions. To prevent $\textit{N}$ from being overproduced, we show that the U(1) gauge coupling constant $\textit{g}$ must be as small as 10 –10 . We also consider the case where the decay of $\textit{ϕ}$ into $\textit{N}$ is kinematically forbidden. In this case, $\textit{N}$ is generated by the scattering of $\textit{Z}$ and the $\textit{g}$ takes values of 10 –10 , which can be explored in collider experiments like FASER and SHiP.

Osamu Seto

Takashi Shimomura

Yoshiki Uchida

Freeze-in sterile neutrino dark matter in a feebly gauged $\textit{B}$ − $\textit{L}$ model

In this work, we use published results by the ATLAS Collaboration collected at LHC Run 2 at a center-of-mass energy of <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> with an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>139</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> to derive lower-mass limits on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> gauge boson associated with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> gauge symmetry. Using dilepton data, we find that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><msup><mi>Z</mi><mo>′</mo></msup></msub><mo>&gt;</mo><mn>4</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> (6 TeV) for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub><mo>=</mo><mn>0.1</mn></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub><mo>=</mo><mn>0.5</mn></math>) in the absence of invisible decays. Once invisible decays are turned on, these limits are substantially relaxed. Assuming an invisible branching ratio of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>BR</mi><mi>inv</mi></msub><mo>=</mo><mn>0.9</mn></math>, the LHC bound is loosened up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><msup><mi>Z</mi><mo>′</mo></msup></msub><mo>&gt;</mo><mn>4.8</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub><mo>=</mo><mn>0.5</mn></math>. This analysis confirms that the LHC is able to impose stricter constraints than the bounds established by experiments at LEP. We also estimate the projected High-Luminosity LHC bounds at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>14</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> and a planned integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">L</mi><mo>=</mo><mn>3</mn><mtext> </mtext><mtext> </mtext><mrow><msup><mrow><mi>ab</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> that will probe <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> masses up to 7.5 TeV.

Brazil

Chile

Farinaldo S. Queiroz

Jilberto Zamora-Saa

Ricardo C. Silva

Y.M. Oviedo-Torres

LHC and HL-LHC bounds on visible and invisible <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> decays in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> model

The gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math> model is well motivated to explain the muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly and dark matter in previous studies. However, the latest <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>NA</mi><mrow><mn>64</mn><mi>μ</mi></mrow></mrow></math> experiment has almost excluded all the parameter space for the muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math>, which indicates that the light dark matter benchmark scenarios interpreting muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math> in previous studies are under significant pressure at present. In light of many recent and future experimental results, we revisit the minimal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> portal dark matter in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math>. Focusing on the phenomenology of dark matter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>χ</mi></math>, we first explore the viable parameter space for light dark matter under various tight constraints. Around the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> resonance, we find that there is still a large parameter space for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub><mo>≳</mo><mn>10</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math> via thermal freeze-out. On the other hand, the constraints on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> above the electroweak scale are quite loose, but are less studied for dark matter. We also investigate the heavy dark matter around the TeV scale and corresponding constraints. A large part of the parameter space for dark matter is within the reach of future experiments.

Zhen-Wei Wang

Zhi-Long Han

Fei Huang

Yi Jin

Honglei Li

Prospects of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> portal dark matter in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><mrow><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>L</mi><mi>μ</mi><mo>−</mo><mi>L</mi><mi>τ</mi></mrow></msub></mrow></mrow></math>

We discuss neutrino sector in models with two Higgs doublet and one singlet scalar fields under local $ U(1)_{L_\alpha- L_\beta} $ symmetry. A neutrino mass matrix is formulated for these models via a type-I seesaw mechanism by introducing right-handed neutrinos. The neutrino mass matrix has more degrees of freedom than minimal scenarios that have only one new scalar field, but its structure is still restricted by symmetry. Subsequently, we find that the sum of neutrino mass can be lower than that of minimal scenarios and easily satisfies observed constraints. In addition, we can fit neutrino data for $ U(1)_{L_e - L_{\mu(\tau)}} $ cases that are disfavored in minimal models. Furthermore, some correlations among sum of neutrino mass and CP violating phases are still observed, although we have more free parameters.

Yuanchao Lou

Takaaki Nomura

Neutrino observables in gauged ${\boldsymbol U({\bf 1})_{\boldsymbol L_{\boldsymbol\alpha}- {\boldsymbol L}_{\boldsymbol\beta}} }$ models with two Higgs doublet and one singlet scalars * Takaaki Nomura supported by the Fundamental Research Funds for the Central Universities

In this letter, we investigate cosmology within the framework of modified <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo stretchy='false'>)</mo></math> gravity using the non-linear model <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>Q</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mi>Q</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>&#945;</mi><msubsup><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow><mrow><mi>n</mi></mrow></msubsup><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>&#946;</mi></math>, where <italic>&#945;</italic>, <italic>&#946;</italic>, and <italic>n</italic> are free parameters. The modified Friedmann equations are derived for a matter-dominated universe, and an analytical solution is obtained. Using Hubble, Pantheon+, and joint datasets, we constrain the model parameters and examine their implications. The results indicate that the model accommodates varying <math altimg='si3.svg'><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math> values, contributing to the Hubble tension, while <math altimg='si4.svg'><mi>n</mi><mo>&#8800;</mo><mn>1</mn></math> suggests deviations from general relativity (GR). The deceleration parameter confirms a transition to acceleration at <math altimg='si5.svg'><msub><mrow><mi>z</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>&#8776;</mo><mn>0.6</mn><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mn>0.8</mn></math>, with present values supporting cosmic acceleration. This model offers a viable alternative to GR-based cosmology.

Kazakhstan

Y. Myrzakulov

Saudi Arabia

Alnadhief H.A. Alfedeel

Morocco

M. Koussour

Uzbekistan

S. Muminov

E.I. Hassan

J. Rayimbaev

Modified cosmology in <italic>f</italic>( <italic>Q</italic>, <italic>L</italic> <inf><italic>m</italic></inf>) gravity

We report on a blinded search for dark matter with single- and few-electron signals in the first science run of XENONnT relying on a novel detector response framework that is physics model dependent. We derive 90% confidence upper limits for dark matter-electron interactions. Heavy and light mediator cases are considered for the standard halo model and dark matter up-scattered in the Sun. We set stringent new limits on dark matter-electron scattering via a heavy mediator with a mass within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>10</mn><mi>–</mi><mn>20</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> and electron absorption of axionlike particles and dark photons for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub></math> below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.03</mn><mtext> </mtext><mtext> </mtext><mi>keV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math>.