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Heavy vector-like quarks decaying to exotic scalars: a case study with triplets
No full textWe investigate the pair production of a vector-like quark triplet with hypercharge 5/3 decaying into top quark and a complex scalar triplet with hypercharge 1 at the LHC. This novel scenario, featuring particles with exotic charges — two quarks with charge 8/3 and 5/3 and a scalar with charge 2 — serves as a unique window to models based on the framework of partial compositeness, where these particles naturally emerge as bound states around the TeV scale. Leveraging on the LHC data we establish exclusion limits on the masses of the vector-like quark and the scalar triplet. Subsequently, we design an analysis strategy aimed at improving sensitivity in the region which is still allowed. Our analysis focuses on two specific regions in the parameter space: the first entails a large mass gap between the vector-like quarks and the scalars, so that the vector-like quarks can decay into the scalars; the second involves a small mass gap, such that this decay is forbidden. To simplify the parameter space, both vector-like quarks and scalars are assumed to be degenerate or almost degenerate within the triplets, such that chain decays between fermions and scalars are suppressed. As a result, we found that final states characterized by a same-sign lepton pair, multiple jets, and high net transverse momentum (i.e. effective mass) will play a pivotal role to unveil this model and, more in general, models characterised by multiple vector-like quarks around the same mass scale during the high luminosity LHC phase
Pulsars in Globular Clusters: Precise clocks to study astrophysics and fundamental physics.
Get PDF<p>The presentation reports about the activities performed during the second part of the first year of the doctorate of Rouhin Nag, in the context of the search for periodic signals in timeseries of radio data acquired while looking at Globular Clusters.</p>
Scienza Aperta per l'accesso alla conoscenza
Get PDF<p>Intervento per il Convegno “La valutazione della ricerca alla prova dei fatti”, Firenze 2024.01.17</p>
Carta Geologica d'Italia alla scala 1:50.000, F. 320 Castel del Piano
No full text<p>Carta Geologica d’Italia alla scala 1:50.000, F. 320 Castel del Piano</p>
Search for flavor changing neutral current interactions of the top quark in final states with a photon and additional jets in proton-proton collisions at <math display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>
No full textA search for the production of a top quark in association with a photon and additional jets via flavor changing neutral current interactions is presented. The analysis uses proton-proton collision data recorded by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb-1. The search is performed by looking for processes where a single top quark is produced in association with a photon, or a pair of top quarks where one of the top quarks decays into a photon and an up or charm quark. Events with an electron or a muon, a photon, one or more jets, and missing transverse momentum are selected. Multivariate analysis techniques are used to discriminate signal and standard model background processes. No significant deviation is observed over the predicted background. Observed (expected) upper limits are set on the branching fractions of top quark decays: B(t→uγ)<0.95×10-5 (1.20×10-5) and B(t→cγ)<1.51×10-5 (1.54×10-5) at 95% confidence level, assuming a single nonzero coupling at a time. The obtained limit for B(t→uγ) is similar to the current best limit, while the limit for B(t→cγ) is significantly tighter than previous results
Two-particle Bose-Einstein correlations and their Lévy parameters in PbPb collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>5.02</mn></mrow></math> TeV
No full textTwo-particle Bose–Einstein momentum correlation functions are studied for charged-hadron pairs in lead-lead collisions at a center-of-mass energy per nucleon pair of sNN=5.02TeV. The data sample, containing 4.27×109 minimum bias events corresponding to an integrated luminosity of 0.607 nb−1, was collected by the CMS experiment in 2018. The experimental results are discussed in terms of a Lévy-type source distribution. The parameters of this distribution are extracted as functions of particle pair average transverse mass and collision centrality. These parameters include the Lévy index or shape parameter α, the Lévy scale parameter R, and the correlation strength parameter λ. The source shape, characterized by α, is found to be neither Cauchy nor Gaussian, implying the need for a full Lévy analysis. Similarly to what was previously found for systems characterized by Gaussian source radii, a hydrodynamical scaling is observed for the Lévy R parameter. The λ parameter is studied in terms of the core-halo model
Measurement of the production cross-section of and mesons in pp collisions at TeV with the ATLAS detector
No full textMeasurements of the differential production cross-sections of prompt and non-prompt and mesons with transverse momenta between 8 and 360 GeV and rapidity in the range |y|<2 are reported. Furthermore, measurements of the non-prompt fractions of and , and the prompt and non-prompt -to- production ratios, are presented. The analysis is performed using 140 fb of TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018
Visual tool for assessing tension-resolving models in the <math display="inline"><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><mtext>-</mtext><msub><mrow><mi>σ</mi></mrow><mrow><mn>8</mn></mrow></msub></mrow></math> plane
No full textBeyond-ΛCDM models have been proposed to address various shortcomings of the standard cosmological model, such as the "Hubble tension." These models often have an impact on the discrepancy in the amplitude of matter clustering, the "σ8 tension." To explore the interplay between the two tensions, we suggest a simple method to visualize the relation between the two parameters: H0 and σ8. For a given extension of the ΛCDM model and dataset, we plot the relation between H0 and σ8 for different amplitudes of the beyond-ΛCDM physics. In this work, we use this visualization method to illustrate the trend of selected cosmological models, including nonminimal Higgs-like inflation, early dark energy, a varying effective electron mass, an extra number of relativistic species and modified dark energy models. Although already studied in the literature, some of these models have not been analyzed in view of the two joint tensions. We stress that the method used here could be a useful diagnostic tool to illustrate the behavior of complex cosmological models with many parameters in the context of the H0 and σ8 tensions
Legacy analysis of dark matter annihilation from the Milky Way dwarf spheroidal galaxies with 14 years of <math display="inline"><mrow><mi mathvariant="italic">Fermi</mi></mrow></math>-LAT data
No full textThe Milky Way dwarf spheroidal satellite galaxies (dSphs) are particularly intriguing targets to search for gamma rays from weakly interacting massive particle dark matter (DM) annihilation or decay. They are nearby, DM-dominated, and lack significant emission from standard astrophysical processes. Previous studies using the Fermi-Large Area Telescope (LAT) of DM-induced emission from dSphs have provided the most robust and stringent constraints on the DM annihilation cross section and mass. We report here an analysis of the Milky Way dSphs using over 14 years of LAT data along with an updated census of dSphs and J-factor estimates. While no individual dSphs are significantly detected, we do find slight excesses with respect to background at the ≳2σ local significance level in both tested annihilation channels (bb¯, τ+τ-) for seven of the dSphs. We do not find a significant DM signal from the combined likelihood analysis of the dSphs (sglobal∼0.5σ), yet a marginal local excess relative to background at a 2–3σ level is observed at a DM mass of Mχ=150–230 GeV (Mχ=30–50 GeV) for DM annihilation into bb¯ (τ+τ-). Given the lack of a significant detection, we place updated constraints on the bb¯ and τ+τ- annihilation channels that are generally consistent with previous recent results. As in past studies, tension is found with some weakly interacting massive particle DM interpretations of the Galactic Center Excess, though the limits are consistent with other interpretations given the uncertainties of the Galactic DM density profile and Galactic Center Excess systematics. Based on conservative assumptions of improved sensitivity with increased Fermi-LAT exposure time and moderate increases in the sample of Milky Way dSphs, we project that the local ∼2σ signal, if real, could approach the ∼4σ local confidence level with additional ∼10 years of observation
Measurement of the absolute branching fraction of the three-body decay <math display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi mathvariant="normal">Ξ</mi><mn>0</mn></msup><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math> and search for <math display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>n</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math>, <math display="inline"><msup><mi mathvariant="normal">Σ</mi><mn>0</mn></msup><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math>, and <math display="inline"><mi mathvariant="normal">Λ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math>
No full textThe Cabbibo-favored decay Λc+→Ξ0K+π0 is studied for the first time using 6.1 fb-1 of e+e- collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay Λc+→Ξ0K+π0 is measured to be (7.79±1.46±0.95)×10-3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Λc+→Ξ(1530)0K+ is (5.99±1.04±0.32)×10-3, which is consistent with the previous result of (5.02±0.99±0.31)×10-3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Λc+→nK+π0 is 7.1×10-4 at the 90% confidence level. The upper limits on the branching fractions of Λc+→Σ0K+π0 and ΛK+π0 are also determined to be 1.8×10-3 and 2.0×10-3, respectively