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Olivares Herrador, J., Latina, A., Aksoy, A., Fuster Martinez, N., Gimeno, B., & Esperante, D. (2024). Implementation of the beam-loading effect in the tracking code RF-track based on a power-diffusive model. Front. Physics, 12, 1348042–11pp.
Abstract: The need to achieve high energies in particle accelerators has led to the development of new accelerator technologies, resulting in higher beam intensities and more compact devices with stronger accelerating fields. In such scenarios, beam-loading effects occur, and intensity-dependent gradient reduction affects the accelerated beam as a consequence of its interaction with the surrounding cavity. In this study, a power-diffusive partial differential equation is derived to account for this effect. Its numerical resolution has been implemented in the tracking code RF-Track, allowing the simulation of apparatuses where transient beam loading plays an important role. Finally, measurements of this effect have been carried out in the CERN Linear Electron Accelerator for Research (CLEAR) facility at CERN, finding good agreement with the RF-Track simulations.
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Balaudo, A., Calore, F., De Romeri, V., & Donato, F. (2024). NAJADS: a self-contained framework for the direct determination of astrophysical J-factors. J. Cosmol. Astropart. Phys., 02(2), 001–33pp.
Abstract: Cosmological simulations play a pivotal role in understanding the properties of the dark matter (DM) distribution in both galactic and galaxy -cluster environments. The characterization of DM structures is crucial for informing indirect DM searches, aiming at the detection of the annihilation (or decay) products of DM particles. A fundamental quantity in these analyses is the astrophysical J -factor. In the DM phenomenology community, J -factors are typically computed through the semi -analytical modelling of the DM mass distribution, which is affected by large uncertainties. With the scope of addressing and possibly reducing these uncertainties, we present NAJADS, a self-contained framework to derive the DM J -factor directly from the raw simulations data. We show how this framework can be used to compute all -sky maps of the J -factor, automatically accounting for the complex 3D structure of the simulated halos and for the boosting of the signal due to the density fluctuations along the line of sight. After validating our code, we present a proof -of -concept application of NAJADS to a realistic halo from the IllustrisTNG suite, and exploit it to make a thorough comparison between our numerical approach and traditional semi -analytical methods. JCAP02(2024)001
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Delgado, R. L., Gomez-Ambrosio, R., Martinez-Martin, J., Salas-Bernardez, A., & Sanz-Cillero, J. J. (2024). Production of two, three, and four Higgs bosons: where SMEFT and HEFT depart. J. High Energy Phys., 03(3), 037–45pp.
Abstract: In this article we study the phenomenological implications of multiple Higgs boson production from longitudinal vector boson scattering in the context of effective field theories. We find compact representations for effective tree-level amplitudes with up to four final state Higgs bosons. Total cross sections are then computed for scenarios relevant at the LHC in which we find the general Higgs Effective Theory (HEFT) prediction avoids the heavy suppression observed in Standard Model Effective Field Theory (SMEFT).
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Baeza-Ballesteros, J., Bijnens, J., Husek, T., Romero-Lopez, F., Sharpe, S. R., & Sjo, M. (2024). The three-pion K-matrix at NLO in ChPT. J. High Energy Phys., 03(3), 048–43pp.
Abstract: The three-particle K-matrix, K-df,K-3, is a scheme-dependent quantity that parametrizes short-range three-particle interactions in the relativistic-field-theory three-particle finite-volume formalism. In this work, we compute its value for systems of three pions in all isospin channels through next-to-leading order in Chiral Perturbation Theory, generalizing previous work done at maximum isospin. We obtain analytic expressions through quadratic order (or cubic order, in the case of zero isospin) in the expansion about the three-pion threshold.
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n_TOF Collaboration(Alcayne, V. et al), Balibrea-Correa, J., Domingo-Pardo, C., Lerendegui-Marco, J., Babiano-Suarez, V., & Ladarescu, I. (2024). A Segmented Total Energy Detector (sTED) optimized for (n,γ) cross-section measurements at n_TOF EAR2. Radiat. Phys. Chem., 217, 11pp.
Abstract: The neutron time-of-flight facility nTOF at CERN is a spallation source dedicated to measurements of neutroninduced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of similar to 4 center dot 10(7) neutrons per nominal proton pulse, which is similar to 50 times higher than the one of Experimental ARea 1 (EAR1) of similar to 8 center dot 10(5) neutrons per pulse. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detector's response, by reducing the active volume per module and by using a photo-multiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to gamma-rays, and provides as well details of the use of the Pulse Height Weighting Technique (PHWT) with this detector. The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV. The detector has already been successfully used in several measurements at nTOF EAR2.
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Ghoshal, A., Gouttenoire, Y., Heurtier, L., & Simakachorn, P. (2023). Primordial black hole archaeology with gravitational waves from cosmic strings. J. High Energy Phys., 08(8), 196–43pp.
Abstract: Light primordial black holes (PBHs) with masses smaller than 10(9) g (10(-24) M-circle dot) evaporate before the onset of Big-Bang nucleosynthesis, rendering their detection rather challenging. If efficiently produced, they may have dominated the universe energy density. We study how such an early matter-dominated era can be probed successfully using gravitational waves (GW) emitted by local and global cosmic strings. While previous studies showed that a matter era generates a single-step suppression of the GW spectrum, we instead find a double-step suppression for local-string GW whose spectral shape provides information on the duration of the matter era. The presence of the two steps in the GW spectrum originates from GW being produced through two events separated in time: loop formation and loop decay, taking place either before or after the matter era. The second step – called the knee – is a novel feature which is universal to any early matter-dominated era and is not only specific to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set constraints on PBHs with masses between 10(6) and 10(9) g for local strings with tension G μ= 10(-11), and PBHs masses between 10(4) and 10(9) g for global strings with symmetry-breaking scale eta = 10(15) GeV. Effects from the spin of PBHs are discussed.
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Jeong, K. S., & Park, W. I. (2023). Cosmology with a supersymmetric local B – L model. J. Cosmol. Astropart. Phys., 11(11), 016–34pp.
Abstract: We propose a minimal gauged U(1)(B-L) extension of the minimal supersymmetric Standard Model (MSSM) which resolves the cosmological moduli problem via thermal inflation, and realizes late-time Affleck-Dine leptogensis so as to generate the right amount of baryon asymmetry at the end of thermal inflation. The present relic density of dark matter can be explained by sneutrinos, MSSM neutralinos, axinos, or axions. Cosmic strings from U(1)(B-L) breaking are very thick, and so the expected stochastic gravitational wave background from cosmic string loops has a spectrum different from the one in the conventional Abelian-Higgs model, as would be distinguishable at least at LISA and DECIGO. The characteristic spectrum is due to a flat potential, and may be regarded as a hint of supersymmetry. Combined with the resolution of moduli problem, the expected signal of gravitational waves constrains the U(1)(B-L) breaking scale to be O(10(12-13)) GeV. Interestingly, our model provides a natural possibility for explaining the observed ultra-high-energy cosmic rays thanks to the fact that the core width of strings in our scenario is very large, allowing a large enhancement of particle emissions from the cusps of string loops. Condensation of LHu flat-direction inside of string cores arises inevitably and can also be the main source of the ultra-high-energy cosmic rays accompanied by ultra-high-energy lightest supersymmetric particles.
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Baran, J. et al, & Brzezinski, K. (2024). Feasibility of the J-PET to monitor the range of therapeutic proton beams. Phys. Medica, 118, 103301–9pp.
Abstract: Purpose: The aim of this work is to investigate the feasibility of the Jagiellonian Positron Emission Tomography (J -PET) scanner for intra-treatment proton beam range monitoring. Methods: The Monte Carlo simulation studies with GATE and PET image reconstruction with CASToR were performed in order to compare six J -PET scanner geometries. We simulated proton irradiation of a PMMA phantom with a Single Pencil Beam (SPB) and Spread -Out Bragg Peak (SOBP) of various ranges. The sensitivity and precision of each scanner were calculated, and considering the setup's cost-effectiveness, we indicated potentially optimal geometries for the J -PET scanner prototype dedicated to the proton beam range assessment. Results: The investigations indicate that the double -layer cylindrical and triple -layer double -head configurations are the most promising for clinical application. We found that the scanner sensitivity is of the order of 10-5 coincidences per primary proton, while the precision of the range assessment for both SPB and SOBP irradiation plans was found below 1 mm. Among the scanners with the same number of detector modules, the best results are found for the triple -layer dual -head geometry. The results indicate that the double -layer cylindrical and triple -layer double -head configurations are the most promising for the clinical application, Conclusions: We performed simulation studies demonstrating that the feasibility of the J -PET detector for PET -based proton beam therapy range monitoring is possible with reasonable sensitivity and precision enabling its pre -clinical tests in the clinical proton therapy environment. Considering the sensitivity, precision and cost-effectiveness, the double -layer cylindrical and triple -layer dual -head J -PET geometry configurations seem promising for future clinical application.
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ATLAS Collaboration(Aad, G. et al), Akiot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2023). Search for flavour-changing neutral tqH interactions with H → γγ in pp collisions at √s=13 TeV using the ATLAS detector. J. High Energy Phys., 12(12), 195–53pp.
Abstract: A search for flavour-changing neutral interactions involving the top quark, the Higgs boson and an up-type quark q ( q = c, u) is presented. The proton-proton collision data set used, with an integrated luminosity of 139 fb(-1), was collected at root s = 13TeV by the ATLAS experiment at the Large Hadron Collider. Both the decay process t -> qH in tt production and the production process pp. tH, with the Higgs boson decaying into two photons, are investigated. No significant excess is observed and upper limits are set on the t. cH and the t. uH branching ratios of 4.3x10(-4) and 3.8x10(-4), respectively, at the 95% confidence level, while the expected limits in the absence of signal are 4.7x10(-4) and 3.9x10(-4). Combining this search with ATLAS searches in the H. t+ t- and H. b <overline> b final states yields observed (expected) upper limits on the t -> cH branching ratio of 5.8 x 10(-4) (3.0 x 10(-4)) at the 95% confidence level. The corresponding observed (expected) upper limit on the t -> uH branching ratio is 4.0 x 10(-4) (2.4 x 10(-4)).
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2023). Search for direct production of electroweakinos in final states with one lepton, jets and missing transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector. J. High Energy Phys., 12(12), 167–63pp.
Abstract: Searches for electroweak production of wino-like chargino pairs, (chi) over tilde (+)(1)(chi) over tilde (-), 1, and of wino-like chargino and next-to-lightest neutralino, (chi) over tilde (+/-)(1)(chi) over tilde (0)(2), are presented. The models explored assume that the charginos decay into a W boson and the lightest neutralino, (chi) over tilde chi(+/-)(1) -> W-+/- (chi) over tilde (0)(1) The next-to-lightest neutralinos are degenerate in mass with the chargino and decay to (chi) over tilde (0)(1) and either a Z or a Higgs boson, (chi) over tilde (0)(2) -> Z (chi) over tildeX(1)(0) or h (chi) over tilde (0)(1). The searches exploit the presence of a single isolated lepton and missing transverse momentum from the W boson decay products and the lightest neutralinos, and the presence of jets from hadronically decaying Z or W bosons or from the Higgs boson decaying into a pair of b-quarks. The searches use 139 fb(-1) of root s = 13TeV proton-proton collisions data collected by the ATLAS detector at the Large Hadron Collider between 2015 and 2018. No deviations from the Standard Model expectations are found, and 95% confidence level exclusion limits are set. Chargino masses ranging from 260 to 520 GeV are excluded for a massless (chi) over tilde (1)(0) in chargino pair production models. Degenerate chargino and next-to-lightest neutralino masses ranging from 260 to 420 GeV are excluded for a massless (chi) over tilde (1)(0) for (chi) over tilde (0)(2) -> Z (chi) over tilde (0)(1). For decays through an on-shell Higgs boson and for mass-splitting between (chi) over tilde (+/-)(1)/(chi) over tilde (0)(2) and (chi) over tilde (0)(1) as small as the Higgs boson mass, mass limits are improved by up to 40 GeV in the range of 200-260 GeV and 280-470 GeV compared to previous ATLAS constraints.
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