L. Masetti

Research summary

An NA48/2 dataset of 1.69x10^7 fully reconstructed pi^0 -> gamma e+ e- decays was used to search for dark-photon production via pi^0 -> gamma A' followed by prompt A' -> e+ e-, setting upper limits on the mixing parameter epsilon^2 stronger than previous bounds in the 9-70 MeV/c^2 mass range and evaluating the sensitivity of NA48/2 to K^+- -> pi^+- A' [1]. The NA48 direct CP-violation measurement combined the 2001 running period with 1997-1999 data to give Re(epsilon'/epsilon) = (14.7 +/- 2.2) x 10^-4 from neutral-kaon two-pion decay rates [2]. The BOOST2012 report at IFIC Valencia evaluated first-principles QCD calculations of jet substructure, the accuracy of Monte Carlo tools, and pile-up resilience for boosted top-quark searches at the LHC [3], and the follow-up BOOST2013 study examined the inter-relationships, complementarity, and jet-radius / p_T dependence of multiple substructure observables [4]. A cusp-like structure in the pi^0 pi^0 invariant mass distribution from K^+- -> pi^+- pi^0 pi^0 was identified in ~2.3x10^7 NA48/2 decays at M_00 ~ 2 m_+, attributed to pi+ pi- -> pi^0 pi^0 final-state charge-exchange scattering, and used with the Cabibbo-Isidori rescattering model to determine a_0 - a_2, the difference between I = 0 and I = 2 pi pi scattering lengths [5][8]. The 1.13 million K_e4 decay sample was analyzed by NA48/2 to extract S- and P-wave hadronic form factors and the phase difference between the two waves, giving precise S-wave scattering lengths a_0^0 = 0.2220 and a_0^2 = -0.0432 [6], and a partial Ke4 sample of more than 670,000 charged decays from 2003 yielded a factor-two improvement in scattering-length extraction precision relative to the earlier measurement [7].

Recent publications

1. Search for the dark photon inπ0decays2015 · Physics Letters B · 310 citationsDOI
2. A precision measurement of direct CP violation in the decay of neutral kaons into two pions2002 · Physics Letters B · 243 citationsDOI
3. Boosted objects and jet substructure at the LHC. Report of BOOST2012, held at IFIC Valencia, 23rd–27th of July 20122014 · The European Physical Journal C · 209 citationsDOI
4. Towards an understanding of the correlations in jet substructure2015 · The European Physical Journal C · 160 citationsDOI
5. Observation of a cusp-like structure in the π0π0 invariant mass distribution from K±→π±π0π0 decay and determination of the ππ scattering lengths2005 · Physics Letters B · 127 citationsDOI
6. Precise tests of low energy QCD from $\mbox {$\mathrm {K}_{\mathrm {e}4}$}$ decay properties2010 · The European Physical Journal C · 117 citationsDOI
7. New high statistics measurement of Ke4 decay form factors and ππ scattering phase shifts2008 · The European Physical Journal C · 108 citationsDOI
8. Observation of a cusp-like structure in the π0π 0 invariant mass distribution from K±→π ±π0π0 decay and determination of the ππ scattering lengths2006 · IRIS Research product catalog (Sapienza University of Rome) · 99 citationsDOI
9. Search for direct CP violating charge asymmetries in K±→π±π+π- and K±→π±π0π0 decays2007 · The European Physical Journal C · 98 citationsDOI
10. Precise measurement of the K±→π±e+e− decay2009 · Physics Letters B · 75 citationsDOI

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External profiles

• ORCID: https://orcid.org/0000-0002-0038-5372
• OpenAlex: openalex.org

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