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Babak, S., Caprini, C., Figueroa, D. G., Karnesis, N., Marcoccia, P., Nardini, G., et al. (2023). Stochastic gravitational wave background from stellar origin binary black holes in LISA. J. Cosmol. Astropart. Phys., 08(8), 034–40pp.
Abstract: We use the latest constraints on the population of stellar origin binary black holes (SOBBH) from LIGO/Virgo/KAGRA (LVK) observations, to estimate the stochastic gravi-tational wave background (SGWB) they generate in the frequency band of LISA. In order to account for the faint and distant binaries, which contribute the most to the SGWB, we extend the merger rate at high redshift assuming that it tracks the star formation rate. We adopt different methods to compute the SGWB signal: we perform an analytical evaluation, we use Monte Carlo sums over the SOBBH population realisations, and we account for the role of the detector by simulating LISA data and iteratively removing the resolvable signals until only the confusion noise is left. The last method allows the extraction of both the expected SGWB and the number of resolvable SOBBHs. Since the latter are few for signal-to-noise ratio thresholds larger than five, we confirm that the spectral shape of the SGWB in the LISA band agrees with the analytical prediction of a single power law. We infer the probability dis-tribution of the SGWB amplitude from the LVK GWTC-3 posterior of the binary population model: at the reference frequency of 0.003 Hz it has an interquartile range of h(2 Omega)GW(f = 3 x 10(-3) Hz) is an element of [5.65, 11.5] x 10(-13), in agreement with most previous estimates. We then perform a MC analysis to assess LISA's capability to detect and characterise this signal. Ac-counting for both the instrumental noise and the galactic binaries foreground, with four years of data, LISA will be able to detect the SOBBH SGWB with percent accuracy, narrowing down the uncertainty on the amplitude by one order of magnitude with respect to the range of possible amplitudes inferred from the population model. A measurement of this signal by LISA will help to break the degeneracy among some of the population parameters, and pro-vide interesting constraints, in particular on the redshift evolution of the SOBBH merger rate.
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Du, M. L., Filin, A., Baru, V., Dong, X. K., Epelbaum, E., Guo, F. K., et al. (2023). Role of Left-Hand Cut Contributions on Pole Extractions from Lattice Data: Case Study for Tcc(3875)+. Phys. Rev. Lett., 131(13), 131903–7pp.
Abstract: We discuss recent lattice data for the T-cc(3875)(+) state to stress, for the first time, a potentially strong impact of left-hand cuts from the one-pion exchange on the pole extraction for near-threshold exotic states. In particular, if the left-hand cut is located close to the two-particle threshold, which happens naturally in the DD* system for the pion mass exceeding its physical value, the effective-range expansion is valid only in a very limited energy range up to the cut and as such is of little use to reliably extract the poles. Then, an accurate extraction of the pole locations requires the one-pion exchange to be implemented explicitly into the scattering amplitudes. Our findings are general and potentially relevant for a wide class of hadronic near-threshold states.
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Forconi, M., Giare, W., Mena, O., Ruchika, Di Valentino, E., Melchiorri, A., et al. (2024). A double take on early and interacting dark energy from JWST. J. Cosmol. Astropart. Phys., 05(5), 097–37pp.
Abstract: The very first light captured by the James Webb Space Telescope (JWST) revealed a population of galaxies at very high redshifts more massive than expected in the canonical Lambda CDM model of structure formation. Barring, among others, a systematic origin of the issue, in this paper, we test alternative cosmological perturbation histories. We argue that models with a larger matter component ohm m and/or a larger scalar spectral index n s can substantially improve the fit to JWST measurements. In this regard, phenomenological extensions related to the dark energy sector of the theory are appealing alternatives, with Early Dark Energy emerging as an excellent candidate to explain (at least in part) the unexpected JWST preference for larger stellar mass densities. Conversely, Interacting Dark Energy models, despite producing higher values of matter clustering parameters such as sigma 8 , are generally disfavored by JWST measurements. This is due to the energy -momentum flow from the dark matter to the dark energy sector, implying a smaller matter energy density. Upcoming observations may either strengthen the evidence or falsify some of these appealing phenomenological alternatives to the simplest Lambda CDM picture.
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Richard, J. M., Valcarce, A., & Vijande, J. (2024). Resonances in the Quark Model. Few-Body Syst., 65(3), 71–11pp.
Abstract: A discussion is presented of the estimates of the energy and width of resonances in constituent models, with focus on the tetraquark states containing heavy quarks.
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Ardu, M., Davidson, S., & Lavignac, S. (2024). Constraining new physics models from μ → e observables in bottom-up EFT. Eur. Phys. J. C, 84(5), 458–36pp.
Abstract: Upcoming experiments will improve the sensitivity to μ-> e processes by several orders of magnitude, and could observe lepton flavour-changing contact interactions for the first time. In this paper, we investigate what could be learned about New Physics from the measurements of these μ-> e observables, using a bottom-up effective field theory (EFT) approach and focusing on three popular models with new particles around the TeV scale (the type II seesaw, the inverse seesaw and a scalar leptoquark). We showed in a previous publication that μ-> e observables have the ability to rule out these models because none can fill the whole experimentally accessible parameter space. In this work we give more details on our EFT formalism and present more complete results. We discuss the impact of some observables complementary to μ-> e transitions (such as the neutrino mass scale and ordering, and LFV tau decays) and draw attention to the interesting appearance of Jarlskog-like invariants in our expressions for the low-energy Wilson coefficients.
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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 magnetic monopoles and stable particles with high electric charges in √s=13 TeV pp collisions with the ATLAS detector. J. High Energy Phys., 11(11), 112–45pp.
Abstract: We present a search for magnetic monopoles and high-electric-charge objects using LHC Run 2 root s = 13TeV proton-proton collisions recorded by the ATLAS detector. A total integrated luminosity of 138 fb(-1) was collected by a specialized trigger. No highly ionizing particle candidate was observed. Considering the Drell-Yan and photon-fusion pair production mechanisms as benchmark models, cross-section upper limits are presented for spin-0 and spin-1/2 magnetic monopoles of magnetic charge 1g(D) and 2g(D) and for high-electric-charge objects of electric charge 20 <= vertical bar z vertical bar <= 100, for masses between 200 GeV and 4000 GeV. The search improves by approximately a factor of three the previous cross-section limits on the Drell-Yan production of magnetic monopoles and high-electric charge objects. Also, the first ATLAS limits on the photon-fusion pair production mechanism of magnetic monopoles and high-electric-charge objects are obtained.
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Li, H. P., Song, J., Liang, W. H., Molina, R., & Oset, E. (2024). Contrasting observables related to the N*(1535) from the molecular or a genuine structure. Eur. Phys. J. C, 84(7), 656–8pp.
Abstract: In this work we compare the predictions for the scattering length and effective range of the channels K-0 Sigma(+), K+Sigma(0), K+ Lambda and eta p, assuming the N*(1535) state as a molecular state of these channels, or an original genuine state, made for instance from three quarks. Looking at very different scenarios, what we conclude is that the predictions of these two pictures are drastically different, to the point that we advise the measurement of these magnitudes, accessible for instance by measuring correlation functions, in order to gain much valuable information concerning the nature of this state.
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Agius, D., Essig, R., Gaggero, D., Scarcella, F., Suczewski, G., & Valli, M. (2024). Feedback in the dark: a critical examination of CMB bounds on primordial black holes. J. Cosmol. Astropart. Phys., 07(7), 003–36pp.
Abstract: If present in the early universe, primordial black holes (PBHs) would have accreted matter and emitted high-energy photons, altering the statistical properties of the Cosmic Microwave Background (CMB). This mechanism has been used to constrain the fraction of dark matter that is in the form of PBHs to be much smaller than unity for PBH masses well above one solar mass. Moreover, the presence of dense dark matter mini -halos around the PBHs has been used to set even more stringent constraints, as these would boost the accretion rates. In this work, we critically revisit CMB constraints on PBHs taking into account the role of the local ionization of the gas around them. We discuss how the local increase in temperature around PBHs can prevent the dark matter mini -halos from strongly enhancing the accretion process, in some cases significantly weakening previously derived CMB constraints. We explore in detail the key ingredients of the CMB bound and derive a conservative limit on the cosmological abundance of massive PBHs.
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Beltran, R., Bolton, P. D., Deppisch, F. F., Hati, C., & Hirsch, M. (2024). Probing heavy neutrino magnetic moments at the LHC using long-lived particle searches. J. High Energy Phys., 07(7), 153–44pp.
Abstract: We explore long-lived particle (LLP) searches using non-pointing photons at the LHC as a probe for sterile-to-sterile and active-to-sterile transition magnetic dipole moments of sterile neutrinos. We consider heavy sterile neutrinos with masses ranging from a few GeV to several hundreds of GeV. We discuss transition magnetic dipole moments using the Standard Model effective field theory and low-energy effective field theory extended by sterile neutrinos (NRSMEFT and NRLEFT) and also provide a simplified UV-complete model example. LLP searches at the LHC using non-pointing photons will probe sterile-to-sterile dipole moments two orders of magnitude below the current best constraints from LEP, while an unprecedented sensitivity to sterile neutrino mass of about 700 GeV is expected for active-to-sterile dipole moments. For the UV model example with one-loop transition magnetic moments, the searches for charged lepton flavour violating processes in synergy with LLP searches at the LHC can probe new physics at several TeV mass scales and provide valuable insights into the lepton flavour structure of new physics couplings.
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Alkofer, R., Llanes-Estrada, F. J., & Salas-Bernardez, A. (2024). Spinning pairs: Supporting 3P0 quark-pair creation from Landau-gauge Green's functions. Phys. Rev. D, 109(7), 074015–21pp.
Abstract: Abundant phenomenology suggests that strong decays from relatively low-excitation hadrons into other hadrons proceed by the creation of a light quark-antiquark pair with zero total angular momentum, the so called 3P0 mechanism originating from a scalar bilinear. Yet the quantum chromodynamics (QCD) interaction is perturbatively mediated by gluons of spin one, and QCD presents a chirally symmetric Lagrangian. Such scalar decay term must be spontaneously generated upon breaking chiral symmetry. We attempt to reproduce this with the help of the quark-gluon vertex in Landau gauge, whose nonperturbative structure has been reasonably elucidated in the last years, and insertions of a uniform, constant chromoelectric field. This is akin to Schwinger pair production in quantum electrodynamics (QED), and we provide a comparison with its two field-insertions diagram. We find that, the symmetry being cylindrical, the adequate quantum numbers to discuss the production are rather 3E0, 3E1, and 3110 as in diatomic molecules, and we indeed find a sizeable contribution of the third decay mechanism, which may give a rationale for the 3P0 phenomenology, as long as the momentum of the produced pair is at or below the scale of the bare or dynamically generated fermion mass. On the other hand, ultrarelativistic fermions are rather ejected with 3E1 quantum numbers. In QED, our results suggest that 3E0 dominates, whereas the constraint of producing a color singlet in QCD leads to 3110 dominance at sub-GeV momenta.
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