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Search for exotic interactions of solar neutrinos in the CDEX-10 experiment

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We investigate exotic neutrino interactions using the 205.4−kg·day dataset from the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a U(1)B–L gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New laboratory limits are derived on dark photon masses below 1 eV/c2 at some benchmark values of Δm412 and g′2sin22θ14.
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Search for exotic interactions of solar neutrinos in the CDEX-10 experiment
X. P. Geng,1L. T. Yang ,1,* Q. Yue,1,K. J. Kang,1Y. J. Li,1H. P. An,1,2 Greeshma C.,3,J. P. Chang,4Y. H. Chen,5
J. P. Cheng,1,6 W. H. Dai,1Z. Deng,1C. H. Fang,7H. Gong,1Q. J. Guo,8X. Y. Guo,5L. He,4S. M. He,5J. W. Hu,1
H. X. Huang,9T. C. Huang,10 H. T. Jia,7X. Jiang,7S. Karmakar,3,H. B. Li,3,J. M. Li,1J. Li,1Q. Y. Li,7R. M. J. Li,7
X. Q. Li,11 Y. L. Li,1Y. F. Liang,1B. Liao,6F. K. Lin,3,S. T. Lin,7J. X. Liu,1S. K. Liu,7Y. D. Liu,6Y. Liu,7Y. Y. Liu,6
Z. Z. Liu,1H. Ma,1Y. C. Mao,8Q. Y. Nie,1J. H. Ning,5H. Pan,4N. C. Qi,5J. Ren,9X. C. Ruan,9Z. She,1M. K. Singh,3,12,
T. X. Sun,6C. J. Tang,7W. Y. Tang,1Y. Tian,1G. F. Wang,6L. Wang,13 Q. Wang,1,2 Y. F. Wang,1Y. X. Wang,8
H. T. Wong,3,S. Y. Wu,5Y. C . W u , 1H. Y. Xing,7R. Xu,1Y. X u , 11 T. Xue,1Y. L. Yan,7N. Yi,1C. X. Yu,11 H. J. Yu,4
J. F. Yue,5M. Zeng,1Z. Zeng,1B. T. Zhang,1F. S. Zhang,6L. Zhang,7Z. H. Zhang,1Z. Y. Zhang,1K. K. Zhao,7
M. G. Zhao,11 J. F. Zhou,5Z. Y. Zhou,9J. J. Zhu,7
(CDEX Collaboration) and Y. C. Wu14
1Key Laboratory of Particle and Radiation Imaging (Ministry of Education)
and Department of Engineering Physics, Tsinghua University, Beijing 100084
2Department of Physics, Tsinghua University, Beijing 100084
3Institute of Physics, Academia Sinica, Taipei 11529
4NUCTECH Company, Beijing 100084
5YaLong River Hydropower Development Company, Chengdu 610051
6College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875
7College of Physics, Sichuan University, Chengdu 610065
8School of Physics, Peking University, Beijing 100871
9Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413
10Sino-French Institute of Nuclear and Technology, Sun Yat-sen University, Zhuhai 519082
11School of Physics, Nankai University, Tianjin 300071
12Department of Physics, Banaras Hindu University, Varanasi 221005
13Department of Physics, Beijing Normal University, Beijing 100875
14Department of Physics and Institute of Theoretical Physics, Nanjing Normal University,
Nanjing 210023
(Received 21 October 2022; revised 22 November 2022; accepted 17 May 2023; published 1 June 2023)
We investigate exotic neutrino interactions using the 205.4-kg · day dataset from the CDEX-10
experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings
of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a Uð1ÞBL
gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-
induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This
work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New
laboratory limits are derived on dark photon masses below 1eV=c2at some benchmark values of Δm2
41 and
g02sin22θ14.
DOI: 10.1103/PhysRevD.107.112002
I. INTRODUCTION
Various cosmological and astrophysical observations at
different scales reveal phenomena beyond the Standard
Model (SM) [1]. The measurement of nonstandard inter-
action (NSI) in the neutrino sector is an attractive approach
to probe beyond-SM physics [2,3]. Current experimental
efforts on neutrino NSI are conducted with different
neutrino sources, such as reactor neutrinos [412], accel-
erator neutrinos [1316], and radioactive sources [1721].
In addition to these terrestrial sources, NSI can also be
*Corresponding author.
yanglt@mail.tsinghua.edu.cn
Corresponding author.
yueq@mail.tsinghua.edu.cn
Participating as a member of TEXONO Collaboration.
Published by the American Physical Society under the terms of
the Creative Commons Attribution 4.0 International license.
Further distribution of this work must maintain attribution to
the author(s) and the published articles title, journal citation,
and DOI. Funded by SCOAP3.
PHYSICAL REVIEW D 107, 112002 (2023)
2470-0010=2023=107(11)=112002(7) 112002-1 Published by the American Physical Society
probed with neutrinos from astrophysical sources, such as
stars [22], supernovae [23,24], terrestrial atmosphere [25],
and others [26]. In this paper, we investigate two attractive
exotic neutrino NSIs, where new gauge boson mediators
(generically denoted as A0) from the hidden sector couple
active or sterile neutrinos with SM particles. Constraints are
placed with data from the CDEX-10 experiment [2732]
using solar neutrino (ν) as the source.
The first NSI model is based on a gauged Uð1ÞBL
symmetry [33,34] with the corresponding A0interacting
with SM particles with a nonzero BL number (baryon
number minus lepton number) at tree level. This global
Uð1Þsymmetry appears in grand unified theory and will
not be violated by chiral and gravitational anomalies. The
symmetry can give rise to neutrino mass when sponta-
neously broken, and the corresponding A0is a dark matter
(DM) candidate. The free parameters are the new gauge
coupling constant (gBL) and the gauge boson mass (MA0).
This additional Uð1ÞBLmediator would lead to a new
interaction between the neutrino and the SM particles
which is measurable by enhanced event rates. The second
NSI model considers the existence of a sterile neutrino (νs)
which couples with A0, called a dark photon, under a new
gauged symmetry Uð1Þ0[33]. The dark photon is a popular
DM candidate and can be a portal between the SM and the
dark sector. Observable interactions between νsand SM
matter are induced by A0. The coupling strength between A0
and νsis parametrized by g0, while that with SM particles
with charge Qis via its kinetic mixing (ε) with the SM
photons. Other interesting NSI models with an extra Uð1Þ
gauge boson [35,36] are beyond the scope of this work.
The p-type point contact germanium (PPCGe) semi-
conductor in ionization mode is ideal for the studies of
exotic processes due to its ultralow-energy threshold of
Oð100 eVeeÞ(eVeerepresents the electron equivalent
energy derived from energy calibration) and low background
level of Oð1count kg1keVee1day1Þ[37,38]. It has been
adopted by the CDEX experiment [2732,3944] for
searches of DM and beyond-SM NSI at the China Jinping
Underground Laboratory (CJPL) where the rock overburden
is about 2400 m [45]. The second phase of the CDEX
experiment, CDEX-10, takes data with a 10-kg PPCGe
detector array, consisting of three triple-element PPCGe
detector strings encapsulated in copper vacuum tubes and
immersed in liquid nitrogen which serves both for cooling
and shielding. The CDEX-10 experimental configuration
was described in Refs. [27,32]. Data taking started in
February 2017, and the physics analysis threshold is
160 eVee [27]. Previous scientific results were published
in Refs. [2731].
II. DATA ANALYSIS
The data analysis of this work is based on a 205.4-kg ·
day dataset from CDEX-10 [2831] and follows the estab-
lished procedures of previous works [27,28,32,42,43].
The energy calibration was performed with zero energy
(defined by random trigger events) and the internal cosmo-
genic K-shell x-ray peaks: 8.98 keVee of 65Zn and
10.37 keVee of 68;71Ge. The signal events are identified
after pedestal noise cut, physics events selection, and bulk/
surface events discrimination [46,47]. The measured
energy spectrum in the detector (Edet) in keVee units after
physics event selections and efficiency corrections is shown
in Fig. 1. The physics analysis threshold is set to be
160 eVee at which the combined signal efficiency (includ-
ing the trigger efficiency and the efficiency for the pulse
shape discrimination) is 4.5% [32]. The characteristic
K-shell x-ray peaks from internal cosmogenic radionu-
clides like 68Ge, 68Ga, 65Zn, 55Fe, 54Mn, and 49V can be
identified. Their intensities are derived from the best fit of
the spectrum [27]. At the sub-keVee energy range relevant
to this analysis, background events are dominated by
Compton scattering of high-energy gamma rays and
internal radioactivity from long-lived cosmogenic isotopes.
Figure 2shows the residual spectrum in the region of 0.16
2.16 keVee after subtracting the contributions from L- and
M-shell x-ray peaks which are derived from the corre-
sponding K-shell line intensities [2731]. This is illustrated
in the inset of Fig. 1. The count rate is several orders of
magnitude larger than the predictions of SM νinteraction.
A minimum-χ2analysis [27,28,31,41] is applied to the
residual spectrum in the range 0.162.16 keVee, in which
χ2is defined as
FIG. 1. The measured energy spectrum with error bars includ-
ing both the statistical and systematical uncertainties based on the
205.4-kg · day dataset of the CDEX-10 experiment [2831]. The
bin width is 100 eVee and the energy range is 0.1611.76 keVee.
The characteristic K-shell x-ray peaks from internal cosmogenic
radionuclides are marked by the isotope symbols in color. Both
the best fit curve of the measured energy spectrum in 411.8 keV,
which is the red line, and the contributions of these radionuclides
derived by the best fit are superimposed. Displayed in the inset
are the contributions of L- and M-shell x-ray peaks derived from
the corresponding K-shell line intensities [48]. The L-shell x-ray
peaks are shown in solid lines. The dashed line represents the
M-shell x-ray peak of 68Ge.
X. P. GENG et al. PHYS. REV. D 107, 112002 (2023)
112002-2
χ2¼X
i
½niSiB2
Δ2
i
;ð1Þ
where niis the measured count at the ith energy bin, and Si
is the expected event rate due to the neutrino NSI model
being probed. Δiis the combination of the statistical and
systematic uncertainties [27], and Bis the flat background
contribution from the Compton scattering of high-energy
gamma rays. The best estimator of the couplings (see
discussion below) at certain mediator mass MA0is evaluated
by minimizing the χ2values. Upper limits at 90% con-
fidence level (CL) are derived by the unified approach [50].
III. FRAMEWORK OF EXOTIC NEUTRINO
INTERACTIONS
Within the SM, neutrinos can interact with Ge and
produce detectable electronic and nuclear recoils via elastic
ν-eand ν-Nelectroweak interactions, respectively. A
popular model for exotic neutrino interactions introduces
a new gauge boson mediator described by
Lint ge¯
eγμeA0
μþgq¯
qγμqA0
μþgν¯
νγμPL;R νA0
μ;ð2Þ
where A0is the extra mediator with mass MA0from a Uð1Þ
gauge group, νcan be either an active or sterile neutrino,
and ge;q;νare the couplings between the A0with the
corresponding fermions. The neutrino-induced scattering
rate is
dR
dEr
¼NT×Z
Emin
ν
dΦ
dEν
dσ
dEr
dEν;ð3Þ
where NTis the number of target nuclei, or electrons, per
unit of mass of the detector material (for ν-Nand ν-e,
respectively), and Emin
νis the minimum neutrino energy
required to generate recoil energy Er.dσ
dEris the differential
cross section, and dΦ
dEνis the differential flux of neutrinos.
The B16-GS98 solar model (also referred to as the high-
metallicity, or HZ model) is adopted, and the values for the
νfluxes are taken from Ref. [51]. Following Eq. (2), the
enhancements of the ν-eand ν-Nscattering cross section
are given by, respectively,
dσðνeνeÞ
dEr
¼ðgegνÞ2me
4πp2
νðM2
A0þ2ErmeÞ2
×½2E2
νþE2
r2ErEνErmem2
ν;ð4Þ
dσðνNνNÞ
dEr
¼ðgNgνÞ2mNF2ðErÞ
4πp2
νðM2
A0þ2ErmNÞ2
×½2E2
νþE2
r2ErEνErmNm2
ν;
ð5Þ
where Eris the recoil energy of the target, Eνis the neutrino
energy, me;N;νare the masses of the electron, target nucleus,
and neutrino, MA0is the mass of the extra gauge boson,
gNis the coherent coupling of the gauge boson with the
nucleus gN¼gpZþgnðAZÞwith gp¼2guþgdand
gn¼guþ2gd, and F2ðErÞis the nuclear form factor which
describes the loss of coherence due to the internal structure
of the nucleus. The conventional Helm form factor [52,53]
is adopted in this analysis. The observed energy deposition
Edet in ν-eis equal to the actual electron recoil energy Er.
For ν-N, the observed total deposited energy Edet is
different from the actual nuclear recoil energy Erand
should be corrected by Edet ¼QnrEr, where the quenching
10-1 100101
10-6
10-4
10-2
100
102
10-2 10-1 100
10-4
10-2
100
102
104
(a)
(b)
FIG. 2. The measured (black data points with uncertainties) and
expected (colored lines) event rates under the two neutrino NSI
models discussed in the text for (a) ν-eand (b) ν-Nscatterings.
Lines A and B correspond to benchmark parameter choices in
model I, while C and D are for model II. For lines C and D, the
parameter sin 2θ14 has been absorbed into the gegνand gNgν. The
energy resolution of CDEX-10 [27,3032] was considered in the
evaluation of the expected event rates. The quenching factor in Ge
for ν-Nis calculated with the
TRIM
package [49]. The CDEX-10
data corresponds to the residual spectra with the L- and M-shell
x-ray contributions subtracted in 0.162.16 keVee, at a bin width
of 100 eVee [27,30,31].
SEARCH FOR EXOTIC INTERACTIONS OF SOLAR NEUTRINOS PHYS. REV. D 107, 112002 (2023)
112002-3
factor Qnr in Ge is calculated by the
TRIM
package [49].
The differential event rates in Ge for the ν-eand ν-N
scattering from νat several benchmark physics parameters
are evaluated and displayed in Figs. 2(a) and 2(b),
respectively.
Within this framework, two neutrino NSI models are
studied and limits are derived with the CDEX-10 data.
A. Model I: Active neutrinos and SM particles
coupled through the Uð1ÞBLgauge boson
The coupling of the A0to SM particles gives rise to
additional contributions to the ν-eand ν-Ndifferential
cross sections. The additional contribution can be classified
into two categories: pure contribution from the Uð1ÞBL
gauge boson and the interference term between the Uð1ÞBL
gauge boson and the SM [34]. Contributions of the
interference terms should be considered when the effects
due to new physics are small or comparable relative to the
SM contribution. This is the case applicable to experiments
where the SM cross sections are measured, such as
TEXONO-CsI [54], Borexino [55], XMASS [56], and
CHARM II [57,58]. Otherwise, when the ranges of new
physics effects are large compared to the SM, the inter-
ference term can in general be neglected [34], and
as the event rates measured in the CDEX-10 experiment
[2731] are much larger than the SM prediction, it is
safe to ignore the interference contribution in this work.
For the pure contribution, the induced NSI is universal
and couples to the BL number of each particle:
3gq¼ge¼gν¼gBL. The active νs are considered,
and the approximation mν0is made.
The expected event rates for ν-eand ν-Nscattering
with benchmark parameters (cases A and B) are displayed
in Figs. 2(a) and 2(b), respectively, and compared with the
measured CDEX-10 data. Cross-sections enhancement
between the two cases follows the 1=ðM2
A0þ2Erme=N Þ2
dependence in Eqs. (4) and (5). At light A0region where
MA0ffiffiffiffiffiffiffiffiffiffiffiffiffiffi
Erme=N
p, the energy spectra scale as E2
r[33],
contributing to enhanced event rates for low threshold
experiments. Upper limits from both channels at 90% CL
on gBLas a function of MA0derived with the unified
approach [50] are depicted in Fig. 3, with constraints
from previous laboratory experiments [34,5460] and
model-dependent astrophysical bounds [6167] superim-
posed. The ν-escattering gives better sensitivity at
MA0<2MeV, while ν-Nscattering dominates at large
MA0. This is due to kinematics constraints as well as me
mNin Eqs. (4) and (5). This work on the CDEX-10 ν
analysis provides limits on Uð1ÞBLof model I: gBL<
1.45 ×106at MA0¼1keV by ν-escattering and gBL<
8.74 ×104at MA0¼10 MeV by ν-Nscattering. The ν-e
scattering analysis places the strongest limit for the
Uð1ÞBLgauge boson with mass MA0<1keV among
solid-state detector-based experiments that use solar
neutrino as the source, which is competitive with those
of current leading laboratory constraints [34,5460].
B. Model II: Sterile neutrinos and SM particles
coupled through a dark photon
The dark photon couples νsto SM particles with an extra
gauged Uð1Þ0symmetry via the mixing with the photons.
The νss are singlet under the SM gauge group but charged
under the Uð1Þ0symmetry. Following Eq. (2),wehave
gν¼g0and gf¼εeQ for f¼e,q, where Qis the charge
of the corresponding fermion, and g0is the Uð1Þ0gauge
coupling constant.
The expected event rate depends on the νsflux. In this
analysis, light νswith a mass less than Oð100ÞkeV is
considered. A small admixture of νsto the νflux can be
produced by oscillation on its way to Earth [33]. The
vacuum oscillation probability in a two-flavor approxima-
tion is given by the usual expression [33]
PðνaνsÞ¼sin22θ14sin2Δm2
41L
4E;ð6Þ
where θ14 is the effective active-sterile neutrino mixing
angle in vacuum, Δm2
41 ¼m2
4m2
1is the splitting between
the squared mass of νsmass eigenstate (m4) and the
dominant νmass eigenstate (m1) in vacuum, Lis the
10-24 10-20 10-15 10-10 10-5 100
10-15
10-10
10-5
10-24 10-6
10-6
FIG. 3. Constraints on a Uð1ÞBLgauge boson with coupling
gBLand mass MA0. The 90% CL limits from CDEX-10 ν
analysis are shown in red, where the solid and dashed lines
represent ν-eand ν-Nscattering, respectively. Other laboratory
constraints from ν-escattering are displayed, with the inset in
expanded scale, showing limits from reactor neutrinos at TEX-
ONO [54] and GEMMA [59], solar neutrinos at Borexino [55]
and XMASS [56], and accelerator neutrino beams at CHARM II
[57,58] and the fixed-target experiment NA64 [60]. Excluded
regions from astrophysics analysis [6167], typically model
dependent, are depicted in light shade. The other constraints
are from Refs. [34,6876].
X. P. GENG et al. PHYS. REV. D 107, 112002 (2023)
112002-4
distance traveled by the neutrino, and Eis the neutrino
energy.
The expected event rate under this NSI model follows a
similar pattern to that of model I as illustrated in Figs. 2(a)
and 2(b) (cases C and D). The cross-section enhancement at
low recoil energy (E2
r) discussed above also applies.
We note that the extra dependence on sin 2θ14 is absorbed
into ge;Ngν. The constraints on the εparameter depend on
Δm2
41 and g02sin22θ14. Studies of these interactions with
νwould yield much higher sensitivities to the couplings
thanks to the large Lvalues compared to terrestrial sources.
Using a minimum-χ2analysis as discussed, no signifi-
cant signal of ν-eor ν-Nscattering is observed. The
90% CL bounds from CDEX-10 νanalysis are shown
in Fig. 4, at the selected parameters Δm2
41 ¼ð10 keVÞ2
and g02sin22θ14 ¼104following earlier analyses of
Borexino [33,55].
Both the ν-eand ν-Nchannels provide improved
sensitivities to some regions of the parameter space. For
MA0<3MeV, the ν-escattering leads to better constraints
in the couplings, while for large MA0, the more stringent
limits come from ν-Nscattering. The CDEX-10 results
from the ν-escattering improve over the Borexino bounds
[33,55] on the kinetic mixing parameter εin MA0<
50 keV. The upper limits at 90% CL of ε<2.89 ×
1010 for MA0¼1keV are derived for model II. The
limits represent the most sensitive laboratory constraints
for light dark photons with mass MA0<1eV. Unlike
earlier experiments following conventional dark photon
analysis [28,7881] where the sensitivities are limited by
the detector threshold, the results from CDEX-10 under the
extended model open a new window for the research of an
extremely low-mass dark photon not covered by other
laboratory, cosmological, and astrophysical bounds. In
particular, the results from our analysis are complementary
to the astrophysical bounds from the Sun/Globular Clusters
which are model specific and can be evaded [33] if the νss
are more massive than 10 keV or are not produced in
a significant amount in the early Universe, or are chame-
leonlike, while our results will be robust against these
variations.
IV. SUMMARY
In this paper, we report results on the searches of
nonstandard neutrino (both active or sterile) interactions
with the dataset corresponding to 205.4-kg · day exposure
from the CDEX-10 experiment. No significant signal is
observed, and the measured event rates are translated into
upper limits on the couplings of two beyond-SM NSIs
using νas a probe. One model postulates a Uð1ÞBL
gauge-boson-induced interaction between active neutrinos
and electron/nucleus and another a kinetically mixed dark-
photon-induced interaction between sterile neutrino and
electron/nucleus. The most stringent constraint among
solid-state detector-based experiments that use solar neu-
trino as a source is placed on the Uð1ÞBLgauge boson with
mass MA0<1keV. A new parameter space of εon a dark
photon for MA0<1eV at some benchmark values of Δm2
41
and g02sin22θ14 is probed. Our results extend the reach in
these NSI models in laboratory measurements, and espe-
cially extend the sensitivity reach in the searches of a dark
photon to extremely low mass.
ACKNOWLEDGMENTS
We would like to thank Joachim Kopp and Pedro
A. N. Machado for useful discussions. This work was
supported by the National Key Research and Develop-
ment Program of China (Grants No. 2017YFA0402200
and No. 2022YFA1605000) and the National Natural
Science Foundation of China (Grants No. 12175112,
No. 12005111, and No. 11725522).
10-24 10-20 10-15 10-10 10-5 100
10-15
10-10
10-5
FIG. 4. Constraints on light A0gauge bosons kinetically mixed
with the photon as a function of the A0mass and the kinetic
mixing parameter ε, at the benchmark values of Δm2
41 ¼
ð10 keVÞ2and g02sin22θ14 ¼104, which follow earlier phe-
nomenological interpretations of Borexino data [55] by Ref. [33].
The 90% CL limits from CDEX-10 νanalysis are shown in red,
where the solid and dashed lines represent ν-eand ν-N,
respectively. The gray lines (CDEX-10) represent previous
CDEX-10 constraints on ϵusing the same dataset under a
different theoretical framework [28]: The solid and dashed
lines stand for DM and solar dark photon, respectively. The
Sun/Globular Clusters bounds marked (*) are valid only for
νs10 keV [33]. Excluded regions from astrophysics analysis
[33,6167], typically model dependent, are depicted in light shade.
The other laboratory constraints are from Refs. [28,55,7781].
SEARCH FOR EXOTIC INTERACTIONS OF SOLAR NEUTRINOS PHYS. REV. D 107, 112002 (2023)
112002-5
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SEARCH FOR EXOTIC INTERACTIONS OF SOLAR NEUTRINOS PHYS. REV. D 107, 112002 (2023)
112002-7
... We provide constraints on the coupling-mass parameters of additional vector mediator Z ′ via CEνNS using the CDEX-10 data [14,15]. The CDEX experiment [16] has the main goal of observing light DM. ...
... In the pp chain, neutrinos are produced via five nuclear reactions called as the 7 B, 8 Be, pp, pep, and hep. In the CNO cycle, neutrinos are commonly produced via decays of 13 N, 15 O, and 17 F. ...
... We analyze the recent CDEX-10 data [15] with associated coherent neutrino-nucleus scattering. The CDEX experiment is part of the China Jinping Underground Laboratory (CJPL) [16]. ...
... We provide constraints on the coupling-mass parameters of additional vector mediator Z ′ via CEνNS using the CDEX-10 data [14,15]. The CDEX experiment [16] has the main goal of observing light DM. ...
... In the pp chain, neutrinos are produced via five nuclear reactions called as the 7 B, 8 Be, pp, pep, and hep. In the CNO cycle, neutrinos are commonly produced via decays of 13 N, 15 O, and 17 F. ...
... We analyze the recent CDEX-10 data [15] with associated coherent neutrino-nucleus scattering. The CDEX experiment is part of the China Jinping Underground Laboratory (CJPL) [16]. ...
... DM direct detection experiments was first proposed in the mid-1980s [44][45][46]. Such searches have already been carried out in various experiments such as LUX [47], PandaX [48], XENON [49,50], LZ [51], DarkSide [52], and, related to our main interest, CDEX [53][54][55][56][57]. The synergy between CEνNS and DM searches expands to the characterization of "the neutrino floor" [58], which will ultimately limit the sensitivity of the current and next generation of experiments at low-mass scales. ...
... We present new constraints on the coupling-mass parameters of light mediator models through CEνNS using the recent CDEX-10 data [56]. The CDEX experiment, whose primary goal is to research light DM, has measured neutrino-nucleus event rates from solar neutrino flux using a p-type point contact germanium (PPCGe) detector array with 205.4 kg · day exposure. ...
... Here, m t is the target mass, m A is the molar mass of the nuclei, and N A is Avogadro's number. The exposure of the CDEX-10 experiment is 205.4 kg · day [56]. The minimum and maximum neutrino energy in the initial state are denoted by E min ν and E max ν , respectively. ...
Article
Full-text available
We investigate new physics with light-neutral mediators through coherent elastic neutrino-nucleus scattering ( CE ν NS ) at low energies. These mediators, with a mass of less than 1 GeV, are common properties for extensions of the Standard Model (SM). We consider general scalar, vector, and tensor interactions allowed by Lorentz invariance and involve universal light mediators accordingly. In addition, we study an additional vector gauge boson with an associated U ( 1 ) ′ gauge group for a variety of models including U ( 1 ) B − L , U ( 1 ) B − 3 L e , U ( 1 ) B − 3 L μ , and U ( 1 ) B − 3 L τ . These models differ in the fermion charges, which determine their contributions within the CE ν NS process. The effects of each model are investigated by embedding them in the SM process using solar neutrino flux. We derive new limits on the coupling-mass plane of these models from the latest CDEX-10 data. We also present projected sensitivities involving the future experimental developments for each model. Our results provide more stringent constraints in some regions, compared to previous works. Furthermore, the projected sensitivities yield an improvement of up to one order of magnitude. Published by the American Physical Society 2024
... In DD experiments solar neutrinos can induce CEνNS events, as well as elastic neutrino-electron scattering. In this context, we consider the latest data of the CDEX-10 experiment [72] which has a primary goal of searching light DM candidates [73]. The CDEX-10 collaboration has reported neutrino-nucleus event rates from solar neutrinos with 205.4 kg day exposure using a p-type point contact germanium (PPCGe) detector array. ...
... In this work, we investigate the sensitivity to probe the transition neutrino magnetic moment on the CEνNS process induced by solar neutrinos. In order to do that, we use the current data from CDEX-10 experiment [72] and the pull approach of the χ 2 function given as [100] ...
Article
Full-text available
In the presence of a transition magnetic moment between active and sterile neutrinos, sterile neutrinos could be produced by neutrino beams electromagnetically upscattering on nuclei. We study the active-sterile neutrino transition magnetic moment through this upscattering in the coherent elastic neutrino-nucleus scattering process induced by solar neutrinos. We place new limits on the transition magnetic moment-sterile neutrino mass plane using the latest data from the CDEX-10 experiment. We also provide projected sensitivities for future measurements. We observe that the projected sensitivities could cover some regions of the parameter space which were previously unexplored for the sterile neutrino mass up to 10\sim 10 MeV.
... In DD experiments solar neutrinos can induce CEνNS events, as well as elastic neutrino-electron scattering. In this context, we consider the latest data of the CDEX-10 experiment [71] which has a primary goal of searching light DM candidates [72]. The CDEX-10 collaboration has reported neutrino-nucleus event rates from solar neutrinos with 205.4 kg·day exposure using a p-type point contact germanium (PPCGe) detector array. ...
... In this work, we investigate the sensitivity to probe the transition neutrino magnetic moment on the CEνNS process induced by solar neutrinos. In order to do that, we use the current data from CDEX-10 experiment [71] and the pull approach of the χ 2 function given as [99] ...
Preprint
In the presence of a transition magnetic moment between active and sterile neutrinos, sterile neutrinos could be produced by neutrino beams electromagnetically upscattering on nuclei. We study the active-sterile neutrino transition magnetic moment through this upscattering in the coherent elastic neutrino-nucleus scattering process induced by solar neutrinos. We place new limits on the transition magnetic moment-sterile neutrino mass plane using the latest data from the CDEX-10 experiment. We also provide projected sensitivities for future measurements. We observe that the projected sensitivities could cover some regions of the parameter space which were previously unexplored for the sterile neutrino mass up to \sim10 MeV.
... We present new constraints on the neutrino magnetic moment through CEνNS using the recent CDEX-10 data [24,25]. We have already derived new constraints for light mediator models through this CDEX-10 data in [26]. ...
... We analysis the recent CDEX-10 data [25] with associated to coherent neutrino-nucleus scattering. The CDEX experiment, which is part of the China Jinping Underground Laboratory (CJPL) [27], have been dedicated for direct detection of DM, using ultra-low energy threshold pPCGe detectors. ...
... The velocity of χ in the SHM follows the Maxwell-Boltzmann distribution with a most probable value of 238 km/s and a cutoff at 544 km/s [10,11]. Time projection chambers (XENON [12], LUX-ZEPLIN [13], PandaX [14], DarkSide [15]), cryogenic calorimeters (CRESST [16], Su-perCDMS [17], EDELWEISS [18]), charge-coupled devices (SENSEI [19], DAMIC [20]), and high purity germanium detectors (CoGeNT [21], CDEX [22][23][24][25][26][27][28][29][30][31][32]) have been operated in searching for χ by investigating their interaction with target electrons or target nuclei. ...
Article
Full-text available
Dark matter (DM) is a major constituent of the Universe. However, no definite evidence of DM particles (denoted as "χ") has been found in DM direct detection (DD) experiments to date. There is a novel concept of detecting χ from evaporating primordial black holes (PBHs). We search for χ emitted from PBHs by investigating their interaction with target electrons. The examined PBH masses range from 1 × 10 15 to 7 × 10 16 g under the current limits of PBH abundance f PBH. Using 205.4 kg·day data obtained from the CDEX-10 experiment conducted in the China Jinping Underground Laboratory, we exclude the χ-electron (χ-e) elastic-scattering cross section σ χe ∼ 5 × 10 −29 cm 2 for χ with a mass m χ 0.1 keV from our results. With the higher radiation background but lower energy threshold (160 eV), CDEX-10 fills a part of the gap in the previous work. If (m χ , σ χe) can be determined in the future, DD experiments are expected to impose strong constraints on f_{PBH} for large M_{PBH}s.
... The detector array comprises three triple-element pPCGe detector strings encapsulated within a vacuum cryostat. Both phases have achieved world-leading results in the direct detection of DM and related research areas [6,7,[18][19][20][21][22][23][24][25][26][27][28][29][30]. ...
Article
Full-text available
CDEX-50 is a next-generation project of the China Dark Matter Experiment (CDEX) that aims to search for dark matter using a 50-kg germanium detector array. This paper comprises a thorough summary of the CDEX-50 dark matter experiment, including an investigation of potential background sources and the development of a background model. Based on the baseline model, the projected sensitivity of weakly interacting massive particle (WIMP) is also presented. The expected background level within the energy region of interest, set to 2–2.5 keVee, is ∼0.01 counts keVee⁻¹ kg⁻¹ day⁻¹. At 90% confidence level, the expected sensitivity to spin-independent WIMP-nucleon couplings is estimated to reach a cross-section of 5.1 × 10⁻⁴⁵ cm² for a WIMP mass of 5 GeV/c² with an exposure objective of 150 kg·year and an analysis threshold of 160 eVee. This science goal will correspond to the most sensitive results for WIMPs with a mass of 2.2–8 GeV/c².
... The velocity of χ in the SHM follows the Maxwell-Boltzmann distribution with a most probable value of 220 km/s and a cutoff at 540 km/s [7,8]. Time projection chambers (XENON [9], LUX-ZEPLIN [10], PandaX [11], Dark-Side [12]), cryogenic calorimeters (CRESST [13], Super-CDMS [14], EDELWEISS [15]), charge-coupled devices (SENSEI [16], DAMIC [17]), and high purity germanium detectors (CoGeNT [18], CDEX [19][20][21][22][23][24][25][26][27][28][29]) have been operated in searching for χ by investigating their interaction with target electrons or target nuclei. ...
Preprint
Full-text available
Dark matter (DM) is a major constituent of the Universe. However, no definite evidence of DM particles (denoted as “χ”) has been found in DM direct detection (DD) experiments to date. There is a novel concept of detecting χ from evaporating primordial black holes (PBHs). We search for χ emitted from PBHs by investigating their interaction with target electrons. The examined PBH masses range from 1×10 15 to 7×10 16 g under the current limits of PBH abundance f P BH. Using 205.4 kg·day data obtained from the CDEX-10 experiment conducted in the China Jinping Underground Laboratory, we exclude the χ–electron (χ–e) elastic-scattering cross section σ χe ∼ 5 × 10 −29 cm 2 for χ with a mass m χ ≲ 0.1 keV from our results. If (m χ , σ χe ) can be determined in the future, DD experiments are expected to impose strong constraints on f P BH for large M P BH s.
... -The existence of dark matter (DM, denoted by χ) in the universe is supported by convincing cosmological evidence [1,2]. Direct detection (DD) experiments such as XENON [3], LUX [4], PandaX [5], DarkSide [6], CRESST [7], SuperCDMS [8], CoGeNT [9] and CDEX [10][11][12][13][14][15][16][17][18][19][20] are dedicated to probing DM-nucleus (χ-N) elastic scattering through spin-independent (SI) and spin-dependent interactions, yet no clear signals have been observed to date. DD experiments rapidly lose sensitivity toward the sub-GeV mass range, because light DM particles carry insufficient energy to generate nuclear recoil signals that exceed the threshold of the detector. ...
Preprint
Full-text available
We report new constraints on light dark matter (DM) boosted by blazars using the 205.4 kg day data from the CDEX-10 experiment located at the China Jinping Underground Laboratory. Two representative blazars, TXS 0506+56 and BL Lacertae are studied. The results derived from TXS 0506+56 exclude DM-nucleon elastic scattering cross sections from 4.6 × 10^{-33} cm^{2} to 1 × 10^{-26} cm^{2} for DM masses between 10 keV and 1 GeV, and the results derived from BL Lacertae exclude DM-nucleon elastic scattering cross sections from 2.4 × 10^{-34} cm^{2} to 1 × 10{-26} cm^{2} for the same range of DM masses. The constraints correspond to the best sensitivities among solid-state detector experiments in the sub-MeV mass range. SuperCDMS [8], CoGeNT [9] and CDEX [10-20] are dedicated to probing DM-nucleus (χ-N) elastic scattering through spin-independent (SI) and spin-dependent interactions, yet no clear signals have been observed to date.
Article
Full-text available
We present improved germanium-based constraints on sub-GeV dark matter via dark matter–electron (χ−e) scattering using the 205.4 kg·day dataset from the CDEX-10 experiment. Using a novel calculation technique, we attain predicted χ−e scattering spectra observable in high-purity germanium detectors. In the heavy mediator scenario, our results achieve 3 orders of magnitude of improvement for mχ larger than 80 MeV/c2 compared to previous germanium-based χ−e results. We also present the most stringent χ−e cross-section limit to date among experiments using solid-state detectors for mχ larger than 90 MeV/c2 with heavy mediators and mχ larger than 100 MeV/c2 with electric dipole coupling. The result proves the feasibility and demonstrates the vast potential of a new χ−e detection method with high-purity germanium detectors in ultralow radioactive background.
Article
Full-text available
A search for a new Z′ gauge boson associated with (un)broken B−L symmetry in the keV–GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×1011 electrons on target collected during 2016–2021 runs, no signal events were found. This allows us to derive new constraints on the Z′−e coupling strength, which, for the mass range 0.3≲mZ′≲100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.
Article
Full-text available
We present new constraints on light dark matter boosted by cosmic rays (CRDM) using the 205.4 kg day data of the CDEX-10 experiment conducted at the China Jinping Underground Laboratory. The Monte Carlo simulation package cjpl_ess was employed to evaluate the Earth shielding effect. Several key factors have been introduced and discussed in our CRDM analysis, including the contributions from heavier CR nuclei than proton and helium, the inhomogeneity of CR distribution, and the impact of the form factor in the Earth attenuation calculation. Our result excludes the dark matter–nucleon elastic scattering cross section region from 1.7×10−30 to 10−26 cm2 for dark matter of 10 keV/c2 to 1 GeV/c2.
Article
Full-text available
We present a measurement of ν_{e} interactions from the Fermilab Booster Neutrino Beam using the MicroBooNE liquid argon time projection chamber to address the nature of the excess of low energy interactions observed by the MiniBooNE Collaboration. Three independent ν_{e} searches are performed across multiple single electron final states, including an exclusive search for two-body scattering events with a single proton, a semi-inclusive search for pionless events, and a fully inclusive search for events containing all hadronic final states. With differing signal topologies, statistics, backgrounds, reconstruction algorithms, and analysis approaches, the results are found to be either consistent with or modestly lower than the nominal ν_{e} rate expectations from the Booster Neutrino Beam and no excess of ν_{e} events is observed.
Article
Full-text available
Recently, the Baksan Experiment on Sterile Transitions (BEST) has presented results [1] confirming the gallium anomaly—a lack of electron neutrinos νe at calibrations of SAGE [2,3] and GALLEX [4]—at the statistical significance exceeding 5σ. This result is consistent with explanation of the gallium anomaly as electron neutrino oscillations into a sterile neutrino, νs. Within this explanation, the BEST experiment itself provides the strongest evidence for the sterile neutrino among all the previous anomalous results in the neutrino sector. We combine the results of gallium experiments with searches for sterile neutrinos in reactor antineutrino experiments (assuming CPT conservation in the 3+1 neutrino sector). While the “gallium” best-fit point in the model parameter space (sterile neutrino mass squared mνs2≈1.25 eV2, sterile-electron neutrino mixing sin22θ≈0.34) is excluded by these searches, a part of the BEST-favored 2σ region with mνs2>5 eV2 is consistent with all of them. Remarkably, the regions advertised by anomalous results of the NEUTRINO-4 experiment [5] overlap with those of the BEST experiment: the best-fit point of the joint analysis is sin22θ≈0.38, mνs2≈7.3 eV2, and the favored region will be explored by the KATRIN experiment [6]. The sterile neutrino explanation of the BEST results would suggest not only the extension of the Standard Model of particle physics but also either serious modifications of the Standard Cosmological Model and Solar Model, or a specific modification of the sterile sector needed to suppress the sterile neutrino production in the early Universe and in the Sun.
Article
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The experiment Neutrino-4 started in 2014 with a detector model and continued with a full-scale detector in 2016–2021. In this article, we describe all the steps of the preparatory work on this experiment. We present all results of the Neutrino-4 experiment with increased statistical accuracy provided to date. The experimental setup is constructed to measure the flux and spectrum of the reactor antineutrinos as a function of distance to the center of the active zone of the SM-3 reactor (Dimitrovgrad, Russia) in the range of 6–12 meters. Using all the collected data, we performed a model-independent analysis to determine the oscillation parameters Δm142 and sin22θ14. The method of coherent summation of measurement results allows us to directly demonstrate the oscillation effect. We present the analysis of possible systematic errors and the MC model of the experiment, which considers the possibility of the effect manifestation at the present precision level. As a result of the analysis, we can conclude that at currently available statistical accuracy, we observe the oscillations at the 2.9σ level with the parameters Δm142=(7.3±0.13st±1.16syst) eV2=(7.3±1.17) eV2 and sin22θ=0.36±0.12stat(2.9σ). Monte Carlo based statistical analysis gave an estimation of the confidence level at 2.7σ. We plan to improve the currently working experimental setup and create a completely new setup in order to increase the accuracy of the experiment by 3 times. We also provide a brief analysis of the general experimental situation in the search for sterile neutrinos.
Article
Full-text available
We present weakly interacting massive particles (WIMPs) search results performed using two approaches of effective field theory from the China Dark Matter Experiment (CDEX), based on the data from both CDEX-1B and CDEX-10 stages. In the nonrela-tivistic effective field theory approach, both time-integrated and annual modulation analyses were used to set new limits for the coupling of WIMP-nucleon effective operators at 90% confidence level (C.L.) and improve over the current bounds in the low m χ region. In the chiral effective field theory approach, data from CDEX-10 were used to set an upper limit on WIMP-pion coupling at 90% C.L. We for the first time extended the limit to the m χ < 6 GeV/c 2 region. WIMP, EFT, CDEX, dark matter, annual modulation PACS number(s): 95.35.+d, 98.70.Vc, 29.40.-n Citation:
Article
The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos ν_{e} observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred to as the "gallium anomaly," which could be interpreted as evidence for oscillations between ν_{e} and sterile neutrino (ν_{s}) states. A 3.414-MCi ^{51}Cr ν_{e} source was placed at the center of two nested Ga volumes and measurements were made of the production of ^{71}Ge through the charged current reaction, ^{71}Ga(ν_{e},e^{-})^{71}Ge, at two average distances. The measured production rates for the inner and the outer targets, respectively, are [54.9_{-2.4}^{+2.5}(stat)±1.4(syst)] and [55.6_{-2.6}^{+2.7}(stat)±1.4(syst)] atoms of ^{71}Ge/d. The ratio (R) of the measured rate of ^{71}Ge production at each distance to the expected rate from the known cross section and experimental efficiencies are R_{in}=0.79±0.05 and R_{out}=0.77±0.05. The ratio of the outer to the inner result is 0.97±0.07, which is consistent with unity within uncertainty. The rates at each distance were found to be similar, but 20%-24% lower than expected, thus reaffirming the anomaly. These results are consistent with ν_{e}→ν_{s} oscillations with a relatively large Δm^{2} (>0.5 eV^{2}) and mixing sin^{2}2θ (≈0.4).
Article
The Baksan Experiment on Sterile Transitions (BEST) probes the gallium anomaly and its possible connections to oscillations between active and sterile neutrinos. Based on the Gallium-Germanium Neutrino Telescope (GGNT) technology of the SAGE experiment, BEST employs two zones of liquid Ga target to explore neutrino oscillations on the meter scale. Oscillations on this short scale could produce deficits in the Ge71 production rates within the two zones, as well as a possible rate difference between the zones. From July 5th to October 13th 2019, the two-zone target was exposed to a primarily monoenergetic, 3.4-MCi Cr51 neutrino source 10 times for a total of 20 independent Ge71 extractions from the two Ga targets. The Ge71 production rates from the neutrino source were measured from July 2019 to March 2020. At the end of these measurements, the counters were filled with Ge71 doped gas and calibrated during November 2020. In this paper, results from the BEST sterile neutrino oscillation experiment are presented in details. The ratio of the measured Ge71 production rates to the predicted rates for the inner and the outer target volumes are calculated from the known neutrino capture cross section. Comparable deficits in the measured ratios relative to predicted values are found for both zones, with the 4σ deviations from unity consistent with the previously reported gallium anomaly. If interpreted in the context of neutrino oscillations, the deficits give best-fit oscillation parameters of Δm2=3.3-2.3+∞eV2 and sin22θ=0.42-0.17+0.15, consistent with νe→νs oscillations governed by a surprisingly large mixing angle.
Article
The JSNS2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for oscillations involving a sterile neutrino in the eV2 mass-splitting range. The experiment will search for the appearance of electron antineutrinos oscillated from muon antineutrinos. The electron antineutrinos are detected via the inverse beta decay process using a liquid scintillator detector. A 1 MW beam of 3 GeV protons incident on a spallation neutron target produces an intense and pulsed neutrino source from pion, muon, and kaon decay at rest. The JSNS2 detector is located 24 m away from the neutrino source and began operation from June 2020. The detector contains 17 tonnes of gadolinium (Gd) loaded liquid scintillator (LS) in an acrylic vessel, as a neutrino target. It is surrounded by 31 tonnes of unloaded LS in a stainless steel tank. Optical photons produced in LS are viewed by 120 R7081 Hamamatsu 10-inch Photomultiplier Tubes (PMTs). In this paper, we describe the JSNS2 detector design, construction, and operation.