D'Auria, G. et al, Gonzalez-Iglesias, D., Gimeno, B., & Pereira, D. E. (2024). The CompactLight Design Study. Eur. Phys. J.-Spec. Top., , 1–208.
Abstract: CompactLight is a Design Study funded by the European Union under the Horizon 2020 research and innovation funding programme, with Grant Agreement No. 777431. CompactLight was conducted by an International Collaboration of 23 international laboratories and academic institutions, three private companies, and five third parties. The project, which started in January 2018 with a duration of 48 months, aimed to design an innovative, compact, and cost-effective hard X-ray FEL facility complemented by a soft X-ray source to pave the road for future compact accelerator-based facilities. The result is an accelerator that can be operated at up to 1 kHz pulse repetition rate, beyond today's state of the art, using the latest concepts for high brightness electron photoinjectors, very high gradient accelerating structures in X-band, and novel short-period undulators. In this report, we summarize the main deliverable of the project: the CompactLight Conceptual Design Report, which overviews the current status of the design and addresses the main technological challenges.
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Coppola, M., Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2024). Masses of magnetized pseudoscalar and vector mesons in an extended NJL model: The role of axial vector mesons. Phys. Rev. D, 109(5), 054014–30pp.
Abstract: We study the mass spectrum of light pseudoscalar and vector mesons in the presence of an external uniform magnetic field B., considering the effects of the mixing with the axial-vector meson sector. The analysis is performed within a two-flavor NJL-like model which includes isoscalar and isovector couplings together with a flavor mixing 't Hooft-like term. The effect of the magnetic field on charged particles is taken into account by retaining the Schwinger phases carried by quark propagators, and expanding the corresponding meson fields in proper Ritus-like bases. The spin-isospin and spin-flavor decomposition of meson mass states is also analyzed. For neutral pion masses it is shown that the mixing with axial vector mesons improves previous theoretical results, leading to a monotonic decreasing behavior with B that is in good qualitative agreement with lattice QCD (LQCD) calculations, both for the case of constant or B-dependent couplings. Regarding charged pions, it is seen that the mixing softens the enhancement of their mass with B. As a consequence, the energy becomes lower than the one corresponding to a pointlike pion, improving the agreement with LQCD results. The agreement is also improved for the magnetic behavior of the lowest.thorn energy state, which does not vanish for the considered range of values of B-a fact that can be relevant in connection with the occurrence of meson condensation for strong magnetic fields.
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Coloma, P., Martin-Albo, J., & Urrea, S. (2024). Discovering long-lived particles at DUNE. Phys. Rev. D, 109(3), 035013–24pp.
Abstract: Long-lived particles (LLPs) arise in many theories beyond the Standard Model. These may be copiously produced from meson decays (or through their mixing with the LLPs) at neutrino facilities and leave a visible decay signal in nearby neutrino detectors. We compute the expected sensitivity of the DUNE liquid argon (LAr) and gaseous argon near detectors (NDs) to light LLP decays. In doing so, we determine the expected backgrounds for both detectors, which have been largely overlooked in the literature, taking into account their angular and energy resolution. We show that searches for LLP decays into muon pairs, or into three pions, would be extremely clean. Conversely, decays into two photons would be affected by large backgrounds from neutrino interactions for both near detectors; finally, the reduced signal efficiency for e thorn e- pairs leads to a reduced sensitivity for ND-LAr. Our results are first presented in a model -independent way, as a function of the mass of the new state and its lifetime. We also provide detailed calculations for several phenomenological models with axionlike particles (coupled to gluons, electroweak bosons, or quark currents). Some of our results may also be of interest for other neutrino facilities using a similar detector technology (e.g., MicroBooNE, SBND, ICARUS, or the T2K near detector).
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Coloma, P., López-Pavón, J., Molina-Bueno, L., & Urrea, S. (2024). New physics searches using ProtoDUNE and the CERN SPS accelerator. J. High Energy Phys., 01(1), 134–18pp.
Abstract: The exquisite capabilities of liquid Argon Time Projection Chambers make them ideal to search for weakly interacting particles in Beyond the Standard Model scenarios. Given their location at CERN the ProtoDUNE detectors may be exposed to a flux of such particles, produced in the collisions of 400 GeV protons (extracted from the Super Proton Synchrotron accelerator) on a target. Here we point out the interesting possibilities that such a setup offers to search for both long-lived unstable particles (Heavy Neutral Leptons, axion-like particles, etc) and stable particles (e.g. light dark matter, or millicharged particles). Our results show that, under conservative assumptions regarding the expected luminosity, this setup has the potential to improve over present bounds for some of the scenarios considered. This could be done within a short timescale, using facilities that are already in place at CERN, and without interfering with the experimental program in the North Area at CERN.
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Centelles Chulia, S., Miranda, O. G., & Valle, J. W. F. (2024). Leptonic neutral-current probes in a short-distance DUNE-like setup. Phys. Rev. D, 109(11), 115007–12pp.
Abstract: Precision measurements of neutrino -electron scattering may provide a viable way to test the nonminimal form of the charged and neutral current weak interactions within a hypothetical near -detector setup for the Deep Underground Neutrino Experiment (DUNE). Although low -statistics, these processes are clean and provide information complementing the results derived from oscillation studies. They could shed light on the scale of neutrino mass generation in low -scale seesaw schemes.
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Chu, X. Y., Garani, R., Garcia-Cely, C., & Hambye, T. (2024). Dark matter bound-state formation in the Sun. J. High Energy Phys., 05(5), 045–32pp.
Abstract: The Sun may capture asymmetric dark matter (DM), which can subsequently form bound-states through the radiative emission of a sub-GeV scalar. This process enables generation of scalars without requiring DM annihilation. In addition to DM capture on nucleons, the DM-scalar coupling responsible for bound-state formation also induces capture from self-scatterings of ambient DM particles with DM particles already captured, as well as with DM bound-states formed in-situ within the Sun. This scenario is studied in detail by solving Boltzmann equations numerically and analytically. In particular, we take into consideration that the DM self-capture rates require a treatment beyond the conventional Born approximation. We show that, thanks to DM scatterings on bound-states, the number of DM particles captured increases exponentially, leading to enhanced emission of relativistic scalars through bound-state formation, whose final decay products could be observable. We explore phenomenological signatures with the example that the scalar mediator decays to neutrinos. We find that the neutrino flux emitted can be comparable to atmospheric neutrino fluxes within the range of energies below one hundred MeV. Future facilities like Hyper-K, and direct DM detection experiments can further test such scenario.
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Chen, M. C., King, S. F., Medina, O., & Valle, J. W. F. (2024). Quark-lepton mass relations from modular flavor symmetry. J. High Energy Phys., 02(2), 160–28pp.
Abstract: The so-called Golden Mass Relation provides a testable correlation between charged-lepton and down-type quark masses, that arises in certain flavor models that do not rely on Grand Unification. Such models typically involve broken family symmetries. In this work, we demonstrate that realistic fermion mass relations can emerge naturally in modular invariant models, without relying on ad hoc flavon alignments. We provide a model-independent derivation of a class of mass relations that are experimentally testable. These relations are determined by both the Clebsch-Gordan coefficients of the specific finite modular group and the expansion coefficients of its modular forms, thus offering potential probes of modular invariant models. As a detailed example, we present a set of viable mass relations based on the Gamma 4 approximately equal to S4 symmetry, which have calculable deviations from the usual Golden Mass Relation.
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Chen, M. C., Li, X. Q., Liu, X. G., Medina, O., & Ratz, M. (2024). Modular invariant holomorphic observables. Phys. Lett. B, 852, 138600–13pp.
Abstract: In modular invariant models of flavor, observables must be modular invariant. The observables discussed so far in the literature are functions of the modulus tau and its conjugate, (tau) over bar. We point out that certain combinations of observables depend only on tau , i.e. are meromorphic, and in some cases even holomorphic functions of tau. These functions, which we dub “invariants” in this Letter, are highly constrained, renormalization group invariant, and allow us to derive many of the models' features without the need for extensive parameter scans. We illustrate the robustness of these invariants in two existing models in the literature based on modular symmetries, Gamma(3) and Gamma(5). We find that, in some cases, the invariants give rise to robust relations among physical observables that are independent of tau. Furthermore, there are instances where additional symmetries exist among the invariants. These symmetries are relevant phenomenologically and may provide a dynamical way to realize symmetries of mass matrices.
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Celestino-Ramirez, J. M., Escrihuela, F. J., Flores, L. J., & Miranda, O. G. (2024). Testing the nonunitarity of the leptonic mixing matrix at FASERv and FASERv2. Phys. Rev. D, 109(1), L011705–6pp.
Abstract: The FASERv experiment has detected the first neutrino events coming from LHC. Near future highstatistic neutrino samples will allow us to search for new physics within the neutrino sector. Motivated by the forthcoming promising FASERv neutrino data, and its successor, FASERv2, we study its potential for testing the unitarity of the neutrino lepton mixing matrix. Although it would be challenging for FASERv and FASERv2 to have strong constraints on this kind of new physics, we discuss its role in contributing to a future improved global analysis.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2024). Observation of WZγ Production in pp Collisions at √s=13 TeV with the ATLAS Detector. Phys. Rev. Lett., 132(2), 021802–21pp.
Abstract: This Letter reports the observation of WZ gamma production and a measurement of its cross section using 140.1 +/- 1.2 fb(-1) of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the bosons decaying leptonically, pp -> WZ gamma -> l'(perpendicular to)nu l(+) l(-)gamma (l(')(+) = e, mu), is measured in a fiducial phasespace region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01 +/- 0.30(stat) +/- 0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50 +/- 0.06 fb. The observed significance of the WZ gamma signal is 6.3 sigma, compared with an expected significance of 5.0 sigma.
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