LHC Searches for Non-Chiral Weakly Charged Multiplets

Because the TeV-scale to be probed at the Large Hadron Collider should shed light on the naturalness, hierarchy, and dark matter problems, most searches to date have focused on new physics signatures motivated by possible solutions to these puzzles. In this paper, we consider some candidates for new states that although not well-motivated from this standpoint are obvious possibilities that current search strategies would miss. In particular we consider vector representations of fermions in multiplets of $SU(2)_L$ with a lightest neutral state. Standard search strategies would fail to find such particles because of the expected small one-loop-level splitting between charged and neutral states.Comment: 16 pages, 9 figure

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Immigrant Latino Neighborhoods and Mortality Among Infants Born to Mexican-Origin Latina Women

To compare the association between neighborhood Latino immigrant concentration and infant mortality by maternal nativity among singleton births to Mexican-origin women in Los Angeles County. Information about births, infant deaths, and infant and maternal characteristics were obtained from geocoded Los Angeles County vital statistics records (2002-2005). Linked data on neighborhood characteristics (census tracts) were obtained from the 2000 census. Logistic regression models were used to predict infant mortality while accounting for spatial clustering by census tract. Two-thirds of births to Mexican-origin mothers were to foreign-born women. Foreign-born mothers were older, had less education, and were more likely to have delivery costs paid by Medicaid than US-born mothers. Infants born to foreign-born women had a lower infant mortality rates than infants born to US-born women (3.8/1,000 live births vs. 4.6, p = .002). Among infants of foreign-born mothers, the odds of infant mortality increased with increasing immigrant concentration (OR 1.29; 95 % CI 1.01-1.66). There was a similar pattern of association between immigrant concentration and mortality for infants of US-born mothers (OR 1.29; 95 % CI 0.99-1.67). In Los Angeles County, the odds of infant mortality among foreign-born Mexican-origin Latina were higher in higher-density immigrant neighborhoods, with a similar trend among US-born mothers. Thus, living in immigrant enclaves likely does not help to explain the lower than expected infant mortality rate among infants born to Latina women. Instead, higher neighborhood Latino immigrant concentration may indicate a neighborhood with characteristics that negatively impact maternal and infant health for Latinos

Changes in Language Services Use by US Pediatricians

BACKGROUND AND OBJECTIVES: Access to appropriate language services is critical for ensuring patient safety and reducing the impact of language barriers. This study compared language services use by US pediatricians in 2004 and 2010 and examined variation in use in 2010 by pediatrician, practice, and state characteristics. METHODS: We used data from 2 national surveys of pediatricians (2004: n = 698; 2010: n = 683). Analysis was limited to postresidency pediatricians with patients with limited English proficiency (LEP). Pediatricians reported use of >= 1 communication methods with LEP patients: bilingual family member, staff, physician, formal interpreter (professional, telephone), and primary-language written materials. Bivariate analyses examined 2004 to 2010 changes in methods used, and 2010 use by characteristics of pediatricians (age, sex, ethnicity), practices (type, location, patient demographics), and states (LEP population, Latino population growth, Medicaid/Children's Health Insurance Program language services reimbursement). Multivariate logistic regression was performed to determine adjusted odds of use of each method. RESULTS: Most pediatricians reported using family members to communicate with LEP patients and families, but there was a decrease from 2004 to 2010 (69.6%, 57.1%, P < .01). A higher percentage of pediatricians reported formal interpreter use (professional and/or telephone) in 2010 (55.8%) than in 2004 (49.7%, P < .05); the increase was primarily attributable to increased telephone interpreter use (28.2%, 37.8%, P < .01). Pediatricians in states with reimbursement had twice the odds of formal interpreter use versus those in nonreimbursing states (odds ratio 2.34; 95% confidence interval 1.24-4.40). CONCLUSIONS: US pediatricians' use of appropriate language services has only modestly improved since 2004. Expanding language services reimbursement may increase formal interpreter use