Warped Supersymmetry Breaking

We address the size of supersymmetry-breaking effects within higher-dimensional settings where the observable sector resides deep within a strongly warped region, with supersymmetry breaking not necessarily localized in that region. Our particular interest is in how the supersymmetry-breaking scale seen by the observable sector depends on this warping. We obtain this dependence in two ways: by computing within the microscopic (string) theory supersymmetry-breaking masses in supermultiplets; and by investigating how warping gets encoded into masses within the low-energy 4D effective theory. We find that the lightest gravitino mode can have mass much less than the straightforward estimate from the mass shift of the unwarped zero mode. This lightest Kaluza-Klein excitation plays the role of the supersymmetric partner of the graviton and has a warped mass m_{3/2} proportional to e^A, with e^A the warp factor, and controls the size of the soft SUSY breaking terms. We formulate the conditions required for the existence of a description in terms of a 4D SUGRA formulation, or in terms of 4D SUGRA together with soft-breaking terms, and describe in particular situations where neither exist for some non-supersymmetric compactifications. We suggest that some effects of warping are captured by a linear $A$ dependence in the Kahler potential. We outline some implications of our results for the KKLT scenario of moduli stabilization with broken SUSY.Comment: 34 pages, 1 figure. v2 Further discussion of dual interpretation and gravitino mas

Neutrino Majorana Masses from String Theory Instanton Effects

Finding a plausible origin for right-handed neutrino Majorana masses in semirealistic compactifications of string theory remains one of the most difficult problems in string phenomenology. We argue that right-handed neutrino Majorana masses are induced by non-perturbative instanton effects in certain classes of string compactifications in which the $U(1)_{B-L}$ gauge boson has a St\"uckelberg mass. The induced operators are of the form $e^{-U}\nu_R\nu_R$ where $U$ is a closed string modulus whose imaginary part transforms appropriately under $B-L$. This mass term may be quite large since this is not a gauge instanton and $Re U$ is not directly related to SM gauge couplings. Thus the size of the induced right-handed neutrino masses could be a few orders of magnitude below the string scale, as phenomenologically required. It is also argued that this origin for neutrino masses would predict the existence of R-parity in SUSY versions of the SM. Finally we comment on other phenomenological applications of similar instanton effects, like the generation of a $\mu$-term, or of Yukawa couplings forbidden in perturbation theory.Comment: 40 pages, 4 figures (v2: added references, small corrections)(v3: minor corrections

Is fluency being ‘neglected’ in the classroom? Teacher understanding of fluency and related classroom practices

This paper reports on a study examining second language (L2) teachers’ understanding of speech fluency and their self-reported classroom practices for promoting it. Qualitative and quantitative data collected from 84 L2 teachers in England were analysed to answer the research questions. In addition to the descriptive statistics and lexical frequency analysis used to explore teacher understanding of fluency, Rossiter, Derwing, Manimtim and Thomson’s (2010) framework was employed to analyse the teachers’ reported classroom practices. The results suggest that teachers often define fluency in a broad sense, with many using fluency and speaking ability interchangeably. Similarly, a large majority of the activities reported by the teachers were useful for enhancing speaking practice rather than focussing on fluency specifically. The findings underline the interaction between teacher understanding of fluency and their classroom practice (Borg, 2003), and highlight a mismatch between what fluency research recommends and what teachers do in class. Though the study highlights the complex and multifaceted nature of L2 oral fluency, we argue that adopting a narrower and more focused definition of fluency could help teachers take a more active and practical approach to promoting it in the classroom

Chiral 4d string vacua with D-branes and NSNS and RR fluxes

We discuss type IIB orientifolds with D-branes, and NSNS and RR field strength fluxes. The D-brane sectors lead to open string spectra with non-abelian gauge symmetry and charged chiral fermions. The closed string field strengths generate a scalar potential stabilizing most moduli. We describe the construction of N=1 supersymmetric models in the context of orientifolds of IIB theory on T^6/Z_2 x Z_2, containing D9-branes with world-volume magnetic fluxes, and illustrate model building possibilities with several explicit examples. We comment on a T-dual picture with D8-branes on non-Calabi-Yau half-flat geometries, and discuss some of the topological properties of such configurations. We also explore the construction of models with fluxes and with D3-branes at singularities and present a non-supersymmetric 3-family SU(5) model.Comment: latex, 49 pages, 2 figure

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society

Measurement of angular parameters from the decay B⁰ → K⁎0^{⁎0} μ⁺ μ⁻ in proton–proton collisions at √s 8 TeV

Angular distributions of the decay B⁰  → K$^{⁎0}$ μ⁺ μ⁻ are studied using a sample of proton–proton collisions at √s=8TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 20.5fb⁻¹ . An angular analysis is performed to determine the P₁ and P$^{\u27}$₅ parameters, where the P$^{\u27}$₅ parameter is of particular interest because of recent measurements that indicate a potential discrepancy with the standard model predictions. Based on a sample of 1397 signal events, the P₁ and P$^{\u27}$₅ parameters are determined as a function of the dimuon invariant mass squared. The measurements are in agreement with predictions based on the standard model

Production of Λ⁺_c baryons in proton-proton and lead-lead collisions at √s_(NN) = 5.02 TeV

The transverse momentum (p_T) spectra of inclusively produced Λ⁺_c baryons are measured via the exclusive decay channel Λ⁺_c →p K⁻π⁺ using the CMS detector at the LHC. Spectra are measured as a function of transverse momentum in proton-proton (pp) and lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measurement is performed within the Λ⁺_c rapidity interval |y|<1 in the p_T range of 5–20GeV/c in pp and 10–20GeV/c in PbPb collisions. The observed yields of Λ⁺_c for p_T of 10–20GeV/c suggest a suppression in central PbPb collisions compared to pp collisions scaled by the number of nucleon-nucleon (NN) interactions. The Λ⁺_c D0 production ratio in pp collisions is compared to theoretical models. In PbPb collisions, this ratio is consistent with the result from pp collisions in their common p_T range