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  • 1
    In: Applied Sciences, MDPI AG, Vol. 11, No. 22 ( 2021-11-22), p. 11076-
    Abstract: The popularity of Machine Learning (ML) has been increasing in recent decades in almost every area, with the commercial and scientific fields being the most notorious ones. In particle physics, ML has been proven a useful resource to make the most of projects such as the Large Hadron Collider (LHC). The main advantage provided by ML is a reduction in the time and effort required for the measurements carried out by experiments, and improvements in the performance. With this work we aim to encourage scientists working with particle colliders to use ML and to try the different alternatives that are available, focusing on the separation of signal and background. We assess some of the most-used libraries in the field, such as Toolkit for Multivariate Data Analysis with ROOT, and also newer and more sophisticated options such as PyTorch and Keras. We also assess the suitability of some of the most common algorithms for signal-background discrimination, such as Boosted Decision Trees, and propose the use of others, namely Neural Networks. We compare the overall performance of different algorithms and libraries in simulated LHC data and produce some guidelines to help analysts deal with different situations. Examples include the use of low or high-level features from particle detectors or the amount of statistics that are available for training the algorithms. Our main conclusion is that the algorithms and libraries used more frequently at LHC collaborations might not always be those that provide the best results for the classification of signal candidates, and fully connected Neural Networks trained with Keras can improve the performance scores in most of the cases we formulate.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2704225-X
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  • 2
    Online Resource
    Online Resource
    American Association of Physics Teachers (AAPT) ; 2022
    In:  The Physics Teacher Vol. 60, No. 8 ( 2022-11-01), p. 690-693
    In: The Physics Teacher, American Association of Physics Teachers (AAPT), Vol. 60, No. 8 ( 2022-11-01), p. 690-693
    Abstract: In this work, we present an experimental approximation to the study of the phenomenon of radioactivity in secondary schools, taking as an analogy the process of release of carbon dioxide in a carbonated beverage. In this way, we intend to facilitate the approach to the mathematical formalism and to the graphical description of this phenomenon, as well as to the understanding of its most important magnitudes: activity or decay rate, decay constant, half-life time, and mean lifetime.
    Type of Medium: Online Resource
    ISSN: 0031-921X , 1943-4928
    Language: English
    Publisher: American Association of Physics Teachers (AAPT)
    Publication Date: 2022
    detail.hit.zdb_id: 2066897-1
    detail.hit.zdb_id: 391692-3
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  • 3
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2019
    In:  Journal of High Energy Physics Vol. 2019, No. 1 ( 2019-01)
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2019, No. 1 ( 2019-01)
    Abstract: We assess the impact of searches at flavor factories for new neutral resonances that couple to both photons and gluons. These are well motivated by “heavy axion” solutions of the strong CP problem and by frameworks addressing both Dark Matter and the Higgs hierarchy problem. We use LHCb public diphoton data around the B s mass to derive the current best limit on these resonances for masses between 4.9 and 6.3 GeV. We estimate that a future LHCb dedicated search would test an axion decay constant of O (TeV) for axion masses in the few-to-tens of GeV, being fully complementary to the low mass ATLAS and CMS searches. We also derive the impact of BABAR searches based on ϒ decays and the future Belle-II reach.
    Type of Medium: Online Resource
    ISSN: 1029-8479
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2027350-2
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2022
    In:  Journal of High Energy Physics Vol. 2022, No. 11 ( 2022-11-07)
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2022, No. 11 ( 2022-11-07)
    Abstract: This paper reports a study of the experimental signatures of hierarchical sectors beyond the Standard Model characterized by a flavour-violating heavy vector and a set of light pseudo-Goldstone bosons a 1,2 , spanning a large range of lifetimes. The non-minimal scalar spectrum triggers novel B decays into multiple leptons that would have escaped the reach of current searches. Novel displaced vertex analyses at LHCb are therefore discussed to probe the hierarchical new physics, extending the scope of the tracking system of the detector. Additionally, the reach of the proposed CODEX-b experiment is studied. By exploiting the use of tracks only reconstructed in subsystems of the detector at the high-level LHCb trigger, $$ \mathcal{B}\left({B}_{s}^{0}\to {a}_{1}{a}_{2}\right) 〈 {10}^{-8} $$ ℬ B s 0 → a 1 a 2 〈 10 − 8 and ℬ( B +  →  K + a 1 a 2 )  〈  10 −9 could be reached in the muon channel across seven orders of magnitude in the lifetime of the Goldstone bosons. Correspondingly, heavy-light particle couplings of order ≲ 1 could be tested, potentially ruling out composite Higgs scenarios where the heavy and light sectors couple strongly.
    Type of Medium: Online Resource
    ISSN: 1029-8479
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2027350-2
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  • 5
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2020
    In:  Journal of High Energy Physics Vol. 2020, No. 1 ( 2020-01)
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2020, No. 1 ( 2020-01)
    Type of Medium: Online Resource
    ISSN: 1029-8479
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2027350-2
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  • 6
    Online Resource
    Online Resource
    American Physical Society (APS) ; 2019
    In:  Physical Review D Vol. 100, No. 5 ( 2019-9-10)
    In: Physical Review D, American Physical Society (APS), Vol. 100, No. 5 ( 2019-9-10)
    Type of Medium: Online Resource
    ISSN: 2470-0010 , 2470-0029
    Language: English
    Publisher: American Physical Society (APS)
    Publication Date: 2019
    detail.hit.zdb_id: 2844732-3
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  • 7
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2020
    In:  Journal of High Energy Physics Vol. 2020, No. 6 ( 2020-06)
    In: Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2020, No. 6 ( 2020-06)
    Type of Medium: Online Resource
    ISSN: 1029-8479
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2027350-2
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  • 8
    In: Journal of Physics G: Nuclear and Particle Physics, IOP Publishing, Vol. 47, No. 9 ( 2020-09-01), p. 090501-
    Abstract: Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton–proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments—as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER—to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity ‘dark showers’, highlighting opportunities for expanding the LHC reach for these signals.
    Type of Medium: Online Resource
    ISSN: 0954-3899 , 1361-6471
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 1472964-7
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  • 9
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 53, No. 12 ( 2022-12), p. 3728-3740
    Abstract: We aim to compare the outcome of patients from urban areas, where the referral center is able to perform thrombectomy, with patients from nonurban areas enrolled in the RACECAT trial (Direct Transfer to an Endovascular Center Compared to Transfer to the Closest Stroke Center in Acute Stroke Patients With Suspected Large Vessel Occlusion). Methods: Patients with suspected large vessel occlusion stroke, as evaluated by a Rapid Arterial Occlusion Evaluation score of ≥5, from urban catchment areas of thrombectomy-capable centers during RACECAT trial enrollment period were included in the Stroke Code Registry of Catalonia. Primary outcome was disability at 90 days, as assessed by the shift analysis on the modified Rankin Scale score, in patients with an ischemic stroke. Secondary outcomes included mortality at 90 days, rate of thrombolysis and thrombectomy, time from onset to thrombolysis, and thrombectomy initiation. Propensity score matching was used to assemble a cohort of patients with similar characteristics. Results: The analysis included 1369 patients from nonurban areas and 2502 patients from urban areas. We matched 920 patients with an ischemic stroke from urban areas and nonurban areas based on their propensity scores. Patients with ischemic stroke from nonurban areas had higher degrees of disability at 90 days (median [interquartle range] modified Rankin Scale score, 3 [2–5] versus 3 [1–5], common odds ratio, 1.25 [95% CI, 1.06–1.48] ); the observed average effect was only significant in patients with large vessel stroke (common odds ratio, 1.36 [95% CI, 1.08–1.65]). Mortality rate was similar between groups(odds ratio, 1.02 [95% CI, 0.81–1.28] ). Patients from nonurban areas had higher odds of receiving thrombolysis (odds ratio, 1.36 [95% CI, 1.16–1.67]), lower odds of receiving thrombectomy(odds ratio, 0.61 [95% CI, 0.51–0.75] ), and longer time from stroke onset to thrombolysis (mean difference 38 minutes [95% CI, 25–52]) and thrombectomy(mean difference 66 minutes [95% CI, 37–95] ). Conclusions: In Catalonia, Spain, patients with large vessel occlusion stroke triaged in nonurban areas had worse neurological outcomes than patients from urban areas, where the referral center was able to perform thrombectomy. Interventions aimed at improving organizational practices and the development of thrombectomy capabilities in centers located in remote areas should be pursued. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02795962.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 1467823-8
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  • 10
    In: JAMA, American Medical Association (AMA), Vol. 327, No. 18 ( 2022-05-10), p. 1782-
    Abstract: In nonurban areas with limited access to thrombectomy-capable centers, optimal prehospital transport strategies in patients with suspected large-vessel occlusion stroke are unknown. Objective To determine whether, in nonurban areas, direct transport to a thrombectomy-capable center is beneficial compared with transport to the closest local stroke center. Design, Setting, and Participants Multicenter, population-based, cluster-randomized trial including 1401 patients with suspected acute large-vessel occlusion stroke attended by emergency medical services in areas where the closest local stroke center was not capable of performing thrombectomy in Catalonia, Spain, between March 2017 and June 2020. The date of final follow-up was September 2020. Interventions Transportation to a thrombectomy-capable center (n = 688) or the closest local stroke center (n = 713). Main Outcomes and Measures The primary outcome was disability at 90 days based on the modified Rankin Scale (mRS; scores range from 0 [no symptoms] to 6 [death] ) in the target population of patients with ischemic stroke. There were 11 secondary outcomes, including rate of intravenous tissue plasminogen activator administration and thrombectomy in the target population and 90-day mortality in the safety population of all randomized patients. Results Enrollment was halted for futility following a second interim analysis. The 1401 enrolled patients were included in the safety analysis, of whom 1369 (98%) consented to participate and were included in the as-randomized analysis (56% men; median age, 75 [IQR, 65-83] years; median National Institutes of Health Stroke Scale score, 17 [IQR, 11-21] ); 949 (69%) comprised the target ischemic stroke population included in the primary analysis. For the primary outcome in the target population, median mRS score was 3 (IQR, 2-5) vs 3 (IQR, 2-5) (adjusted common odds ratio [OR], 1.03; 95% CI, 0.82-1.29). Of 11 reported secondary outcomes, 8 showed no significant difference. Compared with patients first transported to local stroke centers, patients directly transported to thrombectomy-capable centers had significantly lower odds of receiving intravenous tissue plasminogen activator (in the target population, 229/482 [47.5%] vs 282/467 [60.4%]; OR, 0.59; 95% CI, 0.45-0.76) and significantly higher odds of receiving thrombectomy (in the target population, 235/482 [48.8%] vs 184/467 [39.4%]; OR, 1.46; 95% CI, 1.13-1.89). Mortality at 90 days in the safety population was not significantly different between groups (188/688 [27.3%] vs 194/713 [27.2%]; adjusted hazard ratio, 0.97; 95% CI, 0.79-1.18). Conclusions and Relevance In nonurban areas in Catalonia, Spain, there was no significant difference in 90-day neurological outcomes between transportation to a local stroke center vs a thrombectomy-capable referral center in patients with suspected large-vessel occlusion stroke. These findings require replication in other settings. Trial Registration ClinicalTrials.gov Identifier: NCT02795962
    Type of Medium: Online Resource
    ISSN: 0098-7484
    RVK:
    Language: English
    Publisher: American Medical Association (AMA)
    Publication Date: 2022
    detail.hit.zdb_id: 2958-0
    detail.hit.zdb_id: 2018410-4
    SSG: 5,21
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