Recent works have uncovered an excess signal in the parity-odd four-point
correlation function measured from the BOSS spectroscopic galaxy survey. If
physical in origin, this could indicate evidence for new parity-breaking
processes in the scalar sector, most likely from inflation. At heart, these
studies compare the observed four-point correlator to the distribution obtained
from parity-conserving mock galaxy surveys; if the simulations underestimate
the covariance of the data, noise fluctuations may be misinterpreted as a
signal. To test this, we reanalyse the BOSS CMASS + LOWZ parity-odd dataset
with the noise distribution modeled using the newly developed GLAM-Uchuu suite
of mocks. These comprise full N-body simulations that follow the evolution of
$2000^3$ dark matter particles in a $Lambda$CDM universe, and represent a
significant upgrade compared to the formerly MultiDark-Patchy mocks, which were
based on an alternative (non N-body) gravity solver. We find no significant
evidence for parity-violation in the BOSS dataset (with a baseline detection
significance of $1.4sigma$), suggesting that the former signal ($>3.5sigma$
with our data cuts) could be caused by an underestimation of the covariance in
MultiDark-Patchy. The significant differences between results obtained with the
two sets of BOSS-calibrated galaxy catalogs showcases the heightened
sensitivity of beyond-two-point analyses to the treatment of non-linear effects
and indicates that previous constraints may suffer from large systematic
uncertainties.
Recent studies have found an excess signal in the parity-odd four-point correlation function measured from the BOSS spectroscopic galaxy survey. This excess signal could be evidence of new parity-breaking processes in the scalar sector, possibly caused by inflation.
To determine if this signal is physical or if it could be due to noise fluctuations, the BOSS CMASS + LOWZ parity-odd dataset is reanalyzed. The noise distribution in this analysis is modeled using the newly developed GLAM-Uchuu suite of mocks, which are full N-body simulations that follow the evolution of dark matter particles in a $Lambda$CDM universe.
This reanalysis finds no significant evidence for parity-violation in the BOSS dataset, with a baseline detection significance of .4sigma$. This suggests that the previous signal ($>3.5sigma$ with data cuts) may have been caused by an underestimation of the covariance in the MultiDark-Patchy mocks.
The significant differences between the results obtained with the two sets of BOSS-calibrated galaxy catalogs highlight the importance of properly accounting for non-linear effects in beyond-two-point analyses. These differences also indicate that previous constraints may have large systematic uncertainties.
Future Roadmap
Looking ahead, there are several challenges and opportunities on the horizon:
1. Further Analysis
Additional analysis and investigations should be conducted to confirm these findings and verify the robustness of the conclusions. This includes exploring other datasets and performing independent analyses to validate the absence of parity-violation.
2. Improving Covariance Estimation
The underestimation of covariance in the MultiDark-Patchy mocks underscores the need for more accurate and reliable methods of estimating covariance. Developing improved covariance estimation techniques can help prevent the misinterpretation of noise fluctuations as signals, leading to more accurate and reliable measurements.
3. Refining Non-linear Effects Treatment
Beyond-two-point analyses are highly sensitive to the treatment of non-linear effects. Ongoing efforts should focus on refining and enhancing the methods used to account for these non-linear effects. This will improve the accuracy of future measurements and reduce systematic uncertainties.
4. Expanding Mock Catalogs
The use of mock catalogs, such as the GLAM-Uchuu suite, is crucial for understanding and analyzing large-scale structure data. Continuously expanding and improving these mock catalogs will enable more realistic simulations and provide better comparisons with observational data.
5. Exploring New Parity-breaking Processes
The discovery of a potential excess signal in the parity-odd four-point correlation function opens up new opportunities for exploring and understanding parity-breaking processes in the scalar sector. Future research should focus on investigating different inflationary models and studying their implications for large-scale structure formation.
By addressing these challenges and embracing the opportunities, future studies in this field can improve our understanding of the scalar sector, inflation, and the fundamental processes that govern the large-scale structure of the universe.