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We summarize some of the work done by the P3 subgroup on Alternative Models and New Ideas. The working group covered a broad range of topics including a constrained Standard Model from an extra dimension, a discussion of recent ideas addressing the strong CP problem, searches for doubly charged higgs bosons in e gamma collisions, and an update on discovery limits for extra neutral gauge bosons at hadron colliders. The breadth of topics reflects the many ideas and approaches to physics beyond the Standard Model.
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This white paper summarizes the workshop U.S. Cosmic Visions: New Ideas in Dark Matter held at University of Maryland on March 23-25, 2017.
We discuss new ideas for consideration of loop diagrams and angular integrals in $D$-dimensions in QCD. In case of loop diagrams, we propose the covariant formalism of expansion of tensorial loop integrals into the orthogonal basis of linear combinations of external momenta. It gives a very simple presentation for the final results and is more convenient for calculations on computer algebra systems. In case of angular integrals we demonstrate how to simplify the integration of differential cross sections over polar angles. Also we derive the recursion relations, which allow to reduce all occurring angular integrals to a short set of basic scalar integrals. All order $epsilon$-expansion is given for all angular integrals with up to two denominators based on the expansion of the basic integrals and using recursion relations. A geometric picture for partial fractioning is developed which provides a new rotational invariant algorithm to reduce the number of denominators.
The Energy Recovery Linac (ERL) paradigm offers the promise to generate intense electron beams of superior quality with extremely small six-dimensional phase space for many applications in the physical sciences, materials science, chemistry, health, information technology and security. Helmholtz-Zentrum Berlin started in 2010 an intensive R&D programme to address the challenges related to the ERL as driver for future light sources by setting up the bERLinPro (Berlin ERL Project) ERL with 50 MeV beam energy and high average current. The project is close to reach its major milestone in 2020, acceleration and recovery of a high brightness electron beam. The goal of bERLinProCamp 2019 was to discuss scientific opportunities for bERLinPro 2020+. bERLinProCamp 2019 was held on Tue, 17.09.2019 at Helmholtz-Zentrum Berlin, Berlin, Germany. This paper summarizes the main themes and output of the workshop.
CDF has observed a top forward-backward asymmetry discrepant with the Standard Model prediction at 3.4 sigma. We analyze models that could generate the asymmetry, including flavor-violating Ws, horizontal Z_Hs, triplet and sextet diquarks, and axigluons. We consider the detailed predictions of these models for the invariant mass and rapidity distributions of the asymmetry at the parton level, comparing against the unfolded parton-level CDF results. While all models can reproduce the asymmetry with the appropriate choice of mass and couplings, it appears at first examination that the extracted parton-level invariant mass distribution for all models are in conflict with Tevatron observations. We show on closer examination, however, that t tbar events in Z_H and W models have considerably lower selection efficiencies in high invariant mass bins as compared to the Standard Model, so that W, Z_H, and axigluon models can generate the observed asymmetry while being consistent with the total cross-section and invariant mass spectrum. Triplet and sextet models have greater difficulty producing the observed asymmetry while remaining consistent with the total cross-section and invariant mass distribution. To more directly match the models and the CDF results, we proceed to decay and reconstruct the tops, comparing our results against the raw CDF asymmetry and invariant mass distributions. We find that the models that successfully generate the corrected CDF asymmetry at the parton level reproduce very well the more finely binned uncorrected asymmetry. Finally, we discuss the early LHC reach for discovery of these models, based on our previous analysis [arXiv:1102.0018].
Extensive research has documented the immediate impacts of the COVID-19 pandemic on scientists, yet it remains unclear if and how such impacts have shifted over time. Here we compare results from two surveys of principal investigators, conducted between April 2020 and January 2021, along with analyses of large-scale publication data. We find that there has been a clear sign of recovery in some regards, as scientists time spent on their work has almost returned to pre-pandemic levels. However, the latest data also reveals a new dimension in which the pandemic is affecting the scientific workforce: the rate of initiating new research projects. Except for the small fraction of scientists who directly engaged in COVID-related research, most scientists started significantly fewer new research projects in 2020. This decline is most pronounced amongst the same demographic groups of scientists who reported the largest initial disruptions: female scientists and those with young children. Yet in sharp contrast to the earlier phase of the pandemic, when there were large disparities across scientific fields, this loss of new projects appears remarkably homogeneous across fields. Analyses of large-scale publication data reveal a global decline in the rate of new collaborations, especially in non-COVID-related preprints, which is consistent with the reported decline in new projects. Overall, these findings highlight that, while the end of the pandemic may appear in sight in some countries, its large and unequal impact on the scientific workforce may be enduring, which may have broad implications for inequality and the long-term vitality of science.
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