92 research outputs found
Two-mediator dark matter models and cosmic electron excess
The cosmic electron energy spectrum recently observed by the DAMPE experiment
exhibits two interesting features, including a break around 0.9 TeV and a sharp
resonance near 1.4 TeV. In this analysis, we propose a dark matter explanation
to both exotic features seen by DAMPE. In our model, dark matter annihilates in
the galaxy via two different channels that lead to both a narrow resonance
spectrum near 1.4 TeV and electron excess events over an extended energy range
thus generating the break structure around TeV. The two annihilation channels
are mediated by two gauge bosons that interact both with dark matter and with
the standard model fermions. Dark matter annihilations through the s-channel
process mediated by the heavier boson produce monoenergetic electron-positron
pairs leading to the resonance excess. The lighter boson has a mass smaller
than the dark matter such that they can be on-shell produced in dark matter
annihilations in the galaxy; the lighter bosons in the final state subsequently
decay to generate the extended excess events due to the smeared electron energy
spectrum in this process. We further analyze constraints from various
experiments, including HESS, Fermi, AMS, and LHC, to the parameter space of the
model where both excess events can be accounted for. In order to interpret the
two new features in the DAMPE data, dark matter annihilation cross sections in
the current galaxy are typically much larger than the canonical thermal cross
section needed for the correct dark matter relic abundance. This discrepancy,
however, is remedied by the nonperturbative Sommerfeld enhancement because of
the existence of a lighter mediator in the model.Comment: 23 pages, 21 figure
A combined analysis of PandaX, LUX, and XENON1T experiments within the framework of dark matter effective theory
Weakly interacting massive particles are a widely well-probed dark matter
candidate by the dark matter direct detection experiments. Theoretically, there
are a large number of ultraviolet completed models that consist of a weakly
interacting massive particle dark matter. The variety of models makes the
comparison with the direct detection data complicated and often non-trivial. To
overcome this, in the non-relativistic limit, the effective theory was
developed in the literature which works very well to significantly reduce the
complexity of dark matter-nucleon interactions and to better study the nuclear
response functions. In the effective theory framework for a spin-1/2 dark
matter, we combine three independent likelihood functions from the latest
PandaX, LUX, and XENON1T data, and give a joint limit on each effective
coupling. The astrophysical uncertainties of the dark matter distribution are
also included in the likelihood. We further discuss the isospin violating cases
of the interactions. Finally, for both dimension-five and dimension-six
effective theories above the electroweak scale, we give updated limits of the
new physics mass scales.Comment: 33 pages, 11 figures, PandaX run10 data included and version accepted
in JHEP, "code is available at the LikeDM website,
https://likedm.hepforge.org/
Supplement to: Air concentrations of polybrominated diphenyl ethers (PBDEs) in 2002-2004 at a rural site in the Great Lakes
Atmospheric PBDEs were measured on a monthly basis in 2002-2004 at Point Petre, a rural site in the Great Lakes. Average air concentrations were 7.0 ± 13 pg m**-3 for the sum of 14BDE (excluding BDE-209), and 1.8 ± 1.5 pg m**-3 for BDE-209. Concentrations of 3 dominant congeners (i.e., BDE-47, 99, and 209) were comparable to previous measurements at remote/rural sites around the Great Lakes, but much lower than those at urban areas. Weak temperature dependence and strong linear correlations between relatively volatile congeners suggest importance of advective inputs of gaseous species. The significant correlation between BDE-209 and 183 implies their transport inputs associated with particles. Particle-bound percentages were found greater for highly brominated congeners than less brominated ones. These percentages increase with decreasing ambient temperatures. The observed gas/particle partitioning is consistent with laboratory measurements and fits well to the Junge-Pankow model. Using air mass back-trajectories, atmospheric transport to Point Petre was estimated as 76% for BDE-47, 67% for BDE-99, and 70% for BDE-209 from west-northwest and southwest directions. During the same time period, similar congener profiles and concentration levels were found at Alert in the Canadian High Arctic. Different inter-annual variations between Point Petre and Alert indicate that emissions from other regions than North America could also contribute PBDEs in the Arctic. In contrast to weak temperature effect at Point Petre, significant temperature dependence in the summertime implies volatilization emissions of PBDEs at Alert. Meanwhile, episodic observations in the wintertime were likely associated with enhanced inputs through long-range transport during the Arctic Haze period
Leading Power Accuracy in Lattice Calculations of Parton Distributions
In lattice-QCD calculations of parton distribution functions (PDFs) via
large-momentum effective theory, the leading power (twist-three) correction
appears as due to the linear-divergent
self-energy of Wilson line in quasi-PDF operators. For lattice data with hadron
momentum of a few GeV, this correction is dominant in matching, as large
as 30\% or more. We show how to eliminate this uncertainty through choosing the
mass renormalization parameter consistently with the resummation scheme of the
infrared-renormalon series in perturbative matching coefficients. An example on
the lattice pion PDF data at GeV shows an improvement of matching
accuracy by a factor of more than in the expansion region .Comment: Updated to version published on PL
PruMUX: Augmenting Data Multiplexing with Model Compression
As language models increase in size by the day, methods for efficient
inference are critical to leveraging their capabilities for various
applications. Prior work has investigated techniques like model pruning,
knowledge distillation, and data multiplexing to increase model throughput
without sacrificing accuracy. In this paper, we combine two such methods --
structured pruning and data multiplexing -- to compound the speedup gains
obtained by either method. Our approach, PruMUX, obtains up to 7.5-29.5X
throughput improvement over BERT-base model with accuracy threshold from 80% to
74%. We further study various combinations of parameters (such as sparsity and
multiplexing factor) in the two techniques to provide a comprehensive analysis
of the tradeoff between accuracy and throughput in the resulting models. We
then propose Auto-PruMUX, a meta-level model that can predict the
high-performance parameters for pruning and multiplexing given a desired
accuracy loss budget, providing a practical method to leverage the combination
effectively.Comment: Published at Findings of the Association for Computational
Linguistics (ACL 2023
Hybrid Renormalization for Quasi Distribution Amplitudes of A Light Baryon
We develop a hybrid scheme to renormalize quasi distribution amplitudes of a
light baryon on the lattice, which combines the self-renormalization and ratio
scheme. By employing self-renormalization, the UV divergences and linear
divergence at large spatial separations in quasi distribution amplitudes are
removed without introducing extra nonperturbative effects, while making a ratio
with respect to the zero-momentum matrix element can properly remove the UV
divergences in small spatial separations. As a specific application,
distribution amplitudes of the baryon made of are investigated,
and the requisite equal-time correlators, which define quasi distribution
amplitudes in coordinate space, are perturbatively calculated up to the
next-to-leading order in strong coupling constant . These
perturbative equal-time correlators are used to convert lattice QCD matrix
elements to the continuum space during the renormalization process.
Subsequently, quasi distribution amplitudes are matched onto lightcone
distribution amplitudes by integrating out hard modes and the corresponding
hard kernels are derived up to next-to-leading order in including
the hybrid counterterms. These results are valuable in the lattice-based
investigation of the lightcone distribution amplitudes of a light baryon from
the first principles of QCD.Comment: 25 pages, 4 figure
Hydrochemical Characteristics and Quality Assessment of Groundwater under the Impact of Seawater Intrusion and Anthropogenic Activity in the Coastal Areas of Zhejiang and Fujian Provinces, China
AbstractCoastal groundwater is an important resource in the developed region associated with human health and sustainable economic development. To identify the origins of salinity and evaluate the impact of water-rock interactions, seawater intrusion (SWI), and evaporation on groundwater in the coastal areas of Zhejiang and Fujian provinces, a comprehensive investigation was performed. Meanwhile, nitrate and fluoride indicators resulting from the anthropogenic activity and SWI were also considered. At last, the water quality index (WQI) of coastal groundwater was evaluated with geochemical and multivariate statistical methods. The results indicated that (1) the groundwater in coastal areas of Zhejiang and Fujian provinces has been affected by SWI to varying degrees. The analysis of selected ion ratios (Na+/Cl− and Br−/Cl−) and isotopic compositions showed that SWI is the predominant cause of increasing salinity in the groundwater of Zhejiang Province, while the cause is water-rock interactions (ion exchange and mineral weathering) in Fujian Province. The hydrochemical evolution path of groundwater in Zhejiang Province is Ca/Mg-HCO3 to Na-Cl, while a different pattern of Ca/Mg-HCO3 to Na (Mg/Ca)-Cl occurs in Fujian Province. However, the trend of SWI development in both provinces was freshening. (2) Nitrification, sewage infiltration, and SWI increased the NO3− content in groundwater. Some of the NO3− concentration in Fujian Province exceeds the standard, and the nitrogen pollution was more serious than in Zhejiang Province. The F− content in coastal groundwater was affected by SWI and mineral dissolution; the F− content in Zhejiang Province was higher than in Fujian Province, which was close to the groundwater standard limit. The average WQI value of Zhejiang was 103.61, and the WQI of Fujian was 61.69, indicating that the coastal groundwater quality in Fujian Province was better than in Zhejiang Province. The results of the study revealed the impact of SWI and anthropogenic activity on groundwater in the southern coastal zone of China and will be valuable for sustainable groundwater resource management
Lattice Calculation of the Intrinsic Soft Function and the Collins-Soper Kernel
We calculate the soft function using lattice QCD in the framework of large
momentum effective theory incorporating the one-loop perturbative
contributions. The soft function is a crucial ingredient in the lattice
determination of light cone objects using transverse-momentum-dependent (TMD)
factorization. It consists of a rapidity-independent part called intrinsic soft
function and a rapidity-dependent part called Collins-Soper kernel. We have
adopted appropriate normalization when constructing the pseudo-scalar meson
form factor that is needed in the determination of the intrinsic part and
applied Fierz rearrangement to suppress the higher-twist effects. In the
calculation of CS kernel we consider a CLS ensemble other than the MILC
ensemble used in a previous study. We have also compared the applicability of
determining the CS kernel using quasi TMDWFs and quasi TMDPDFs. As an example,
the determined soft function is used to obtain the physical TMD wave functions
(WFs) of pion and unpolarized iso-vector TMD parton distribution functions
(PDFs) of proton.Comment: 24 pages, 19 figures, published versio
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