Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Urban Oxidation Flow Reactor Measurements Reveal Significant Secondary Organic Aerosol Contributions from Volatile Emissions of Emerging Importance

Mobile sampling studies have revealed enhanced levels of secondary organic aerosol (SOA) in source-rich urban environments. While these enhancements can be from rapidly reacting vehicular emissions, it was recently hypothesized that nontraditional emissions (volatile chemical products and upstream emissions) are emerging as important sources of urban SOA. We tested this hypothesis by using gas and aerosol mass spectrometry coupled with an oxidation flow reactor (OFR) to characterize pollution levels and SOA potentials in environments influenced by traditional emissions (vehicular, biogenic), and nontraditional emissions (e.g., paint fumes). We used two SOA models to assess contributions of vehicular and biogenic emissions to our observed SOA. The largest gap between observed and modeled SOA potential occurs in the morning-time urban street canyon environment, for which our model can only explain half of our observation. Contributions from VCP emissions (e.g., personal care products) are highest in this environment, suggesting that VCPs are an important missing source of precursors that would close the gap between modeled and observed SOA potential. Targeted OFR oxidation of nontraditional emissions shows that these emissions have SOA potentials that are similar, if not larger, compared to vehicular emissions. Laboratory experiments reveal large differences in SOA potentials of VCPs, implying the need for further characterization of these nontraditional emissions

Reduced Ultrafine Particle Concentration in Urban Air: Changes in Nucleation and Anthropogenic Emissions

Nucleation is an important source of ambient ultrafine particles (UFP). We present observational evidence of the changes in the frequency and intensity of nucleation events in urban air by analyzing long-term particle size distribution measurements at an urban background site in Pittsburgh, Pennsylvania during 2001–2002 and 2016–2017. We find that both frequency and intensity of nucleation events have been reduced by 40–50% over the past 15 years, resulting in a 70% reduction in UFP concentrations from nucleation. On average, the particle growth rates are 30% slower than 15 years ago. We attribute these changes to dramatic reductions in SO₂ (more than 90%) and other pollutant concentrations. Overall, UFP concentrations in Pittsburgh have been reduced by ∼48% in the past 15 years, with a ∼70% reduction in nucleation, ∼27% in weekday local sources (e.g., weekday traffic), and 49% in the regional background. Our results highlight that a reduction in anthropogenic emissions can considerably reduce nucleation events and UFP concentrations in a polluted urban environment

Identifying Patterns and Sources of Fine and Ultrafine Particulate Matter in London Using Mobile Measurements of Lung-Deposited Surface Area.

Funder: Valhalla FoundationFunder: High Meadows FoundationFunder: Children's Investment Fund FoundationFunder: Clean Air FundWe performed more than a year of mobile, 1 Hz measurements of lung-deposited surface area (LDSA, the surface area of 20-400 nm diameter particles, deposited in alveolar regions of lungs) and optically assessed fine particulate matter (PM2.5), black carbon (BC), and nitrogen dioxide (NO2) in central London. We spatially correlated these pollutants to two urban emission sources: major roadways and restaurants. We show that optical PM2.5 is an ineffective indicator of tailpipe emissions on major roadways, where we do observe statistically higher LDSA, BC, and NO2. Additionally, we find pollutant hot spots in commercial neighborhoods with more restaurants. A low LDSA (15 μm2 cm-3) occurs in areas with fewer major roadways and restaurants, while the highest LDSA (25 μm2 cm-3) occurs in areas with more of both sources. By isolating areas that are higher in one source than the other, we demonstrate the comparable impacts of traffic and restaurants on LDSA. Ratios of hyperlocal enhancements (ΔLDSA:ΔBC and ΔLDSA:ΔNO2) are higher in commercial neighborhoods than on major roadways, further demonstrating the influence of restaurant emissions on LDSA. We demonstrate the added value of using particle surface in identifying hyperlocal patterns of health-relevant PM components, especially in areas with strong vehicular emissions where the high LDSA does not translate to high PM2.5

Abstracts of National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020

This book presents the abstracts of the papers presented to the Online National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020 (RDMPMC-2020) held on 26th and 27th August 2020 organized by the Department of Metallurgical and Materials Science in Association with the Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, India. Conference Title: National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020Conference Acronym: RDMPMC-2020Conference Date: 26–27 August 2020Conference Location: Online (Virtual Mode)Conference Organizer: Department of Metallurgical and Materials Engineering, National Institute of Technology JamshedpurCo-organizer: Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, IndiaConference Sponsor: TEQIP-

Evidence for X(3872) in Pb-Pb Collisions and Studies of its Prompt Production at sNN\sqrt {s_{NN}}=5.02 TeV

The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The $X(3872)$ production is studied in lead-lead (Pb-Pb) collisions at a center-of-mass energy of $\sqrt {s_{NN}}$ 5.02 TeV per nucleon pair, using the decay chain $X(3872) → J/ψ π^+ π^− → μ^+ μ^- π^+ π^−$. The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of 1.7 nb$^{-1}$. The measurement is performed in the rapidity and transverse momentum ranges $|y|<$ 1.6 and 15$< p_T <$ 50 GeV/c. The significance of the inclusive $X(3872)$ signal is 4.2 standard deviations. The prompt $X(3872)$ to $ψ2S$ yield ratio is found to be $ρ^{Pb-Pb} =1.08±0.49(stat)±0.52(syst)$, to be compared with typical values of 0.1 for pp collisions. This result provides a unique experimental input to theoretical models of the $X(3872)$ production mechanism, and of the nature of this exotic state

Azimuthal correlations in Z +jets events in proton–proton collisions at s=13 TeV\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V}

The production of Z bosons associated with jets is measured in $\text {p}\text {p}$ collisions at $\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V}$ with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3$\,\text {fb}^{-1}$. The multiplicity of jets with transverse momentum $p_{\textrm{T}} > 30\,\text {Ge}\hspace{-.08em}\text {V}$ is measured for different regions of the Z boson’s $p_{\textrm{T}} (\text {Z })$, from lower than 10$\,\text {Ge}\hspace{-.08em}\text {V}$ to higher than 100$\,\text {Ge}\hspace{-.08em}\text {V}$. The azimuthal correlation $\varDelta \phi$ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of $p_{\textrm{T}} (\text {Z })$. The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low $p_{\textrm{T}} (\text {Z })$ regions

Search for direct pair production of supersymmetric partners of τ\tau leptons in the final state with two hadronically decaying τ\tau leptons and missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

A search for the direct production of a pair of $τ$ sleptons, the supersymmetric partners of $τ$ leptons, is presented. Each $τ$ slepton is assumed to decay to a $τ$ lepton and the lightest supersymmetric particle (LSP), which is assumed to be stable and to not interact in the detector, leading to an imbalance in the total reconstructed transverse momentum. The search is carried out in events identified as containing two $τ$ leptons, each decaying to one or more hadrons and a neutrino, and significant transverse momentum imbalance. In addition to scenarios in which the $τ$ sleptons decay promptly, the search also addresses scenarios in which the $τ$ sleptons have sufficiently long lifetimes to give rise to nonprompt $τ$ leptons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC with the CMS detector in 2016–2018, and correspond to an integrated luminosity of 138 fb$^{-1}$. No significant excess is seen with respect to standard model expectations. Upper limits on cross sections for the pair production of $τ$ sleptons are obtained in the framework of simplified models. In a scenario in which the $τ$ sleptons are superpartners of left-handed $τ$ leptons, and each undergoes a prompt decay to a $τ$ lepton and a nearly massless LSP, $τ$ slepton masses between 115 and 340 GeV are excluded. In a scenario in which the lifetime of the $τ$ sleptons corresponds to $cτ_0$ = 0.1 mm, where $τ_0$ represents the mean proper lifetime of the $τ$ slepton, masses between 150 and 220 GeV are excluded