Publications

Order by: publication date number of citations

• Tau-decay determination of the strong coupling

  Antonio Pich

  SciPost Phys. Proc. 1, 036 (2019) · published 21 February 2019 | Toggle abstract · pdf

  We review the current status of the determination of the strong coupling from tau decay. Using the most recent release of the ALEPH data, a very comprehensive phenomenological analysis has been performed, exploring all strategies previously considered in the literature and several complementary approaches. Once their actual uncertainties are properly assessed, the results from all adopted methodologies are in excellent agreement, leading to a very robust and reliable value of the strong coupling, $\alpha_s^{(n_f=3)}(m_\tau^2) = 0.328\pm 0.013$, which implies $\alpha_s^{(n_f=5)}(M_Z^2) = 0.1197\pm 0.0015$.

  4 citations

• Proton gravitational form factors in a light-front quark-diquark model

  Dipankar Chakrabarti, Chandan Mondal, Asmita Mukherjee, Sreeraj Nair, Xingbo Zhao

  SciPost Phys. Proc. 8, 113 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We present a recent calculation of the gravitational form factors (GFFs) of proton using the light-front quark-diquark model constructed by the soft-wall AdS/QCD. The four GFFs $~A(Q^2)$ , $B(Q^2)$ , $C(Q^2)$ and $\bar{C}(Q^2)$ are calculated in this model. We also show the pressure and shear distributions of quarks inside the proton. The GFFs, $A(Q^2)$ and $B(Q^2)$ are found to be consistent with the lattice QCD, while the qualitative behavior of the $D$-term form factor is in agreement with the extracted data from the deeply virtual Compton scattering (DVCS) experiments at JLab, the lattice QCD, and the predictions of different phenomenological models.

  4 citations

• Non-standard interactions in $\tau^- \to (\pi^-\eta,\pi^-\pi^0)\nu_{\tau}$ decays

  Gabriel López Castro

  SciPost Phys. Proc. 1, 008 (2019) · published 18 February 2019 | Toggle abstract · pdf

  Originally thought as clean processes to study the hadronization of the weak currents, semileptonic tau lepton decays can be useful to set constraints on non-standard (NS) weak interactions. In this talk we summarize our recent studies on the effects of NS interactions in $\tau^- \to (\pi^-\pi^0,\pi^-\eta)\nu_{\tau}$ decays. We find that experimental data on these decays provide strong constraints on NS scalar and tensor interactions, respectively. Further improved measurements at Belle II and a better knowledge of necessary tensor and scalar form factors will allow to set limits on these NS interactions that are similar or better to contraints obtained from other low-energy processes

  4 citations

• Searching for muon to electron conversion: The Mu2e experiment at Fermilab

  Richard Bonventre on behalf of the Mu2e Collaboration

  SciPost Phys. Proc. 1, 038 (2019) · published 21 February 2019 | Toggle abstract · pdf

  The Mu2e experiment will measure the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. Mu2e will improve the previous measurement by four orders of magnitude, reaching a 90% C.L. limit of $8\times10^{-17}$ on the conversion rate. The experiment will reach mass scales of nearly $10^4$ TeV, far beyond the direct reach of colliders. The experiment is sensitive to a wide range of new physics, complementing and extending other CLFV searches. Mu2e is under design and construction at the Muon Campus of Fermilab; we expect to start taking physics data in 2022 with 3 years of running to achieve our target sensitivity.

  4 citations

• Local Unitarity

  Zeno Capatti

  SciPost Phys. Proc. 7, 024 (2022) · published 21 June 2022 | Toggle abstract · pdf

  Within the Local Unitarity formalism, any physical cross-section is re-written in such a way that cancellations of infrared singularities between real and virtual contributions are realised locally. Consequently, phase-space and loop integrals are regulated locally without the need of any counter-terms or dimensional regularisation aside from those strictly needed to achieve ultraviolet regularisation. This Local Unitarity representation is especially suitable to direct Monte Carlo integration. As such, it offers a clear and direct path to automate the computation of fixed-order differential observables in Quantum Field Theories.

  3 citations

• Hidden-orders of uranium compounds

  Hisatomo Harima

  SciPost Phys. Proc. 11, 006 (2023) · published 5 June 2023 | Toggle abstract · pdf

  Hidden order is often discussed in strongly correlated electron systems. In many cases, it shows no magnetic responses, so that the order parameter is electric, but accompanies few lattice distortion. In the Jahn-Teller cases, the ordered state gains its energy by changing inter-site mixing strengths, leading a larger structural distortion with lowering symmetry. On the contrary, in strongly correlated electron systems, the strong intra-site Coulomb energy causes the the symmetry lowering. It is not necessary to bring the lattice distortion for lowering local site symmetry. In fact, lower symmetry of electronic state than the symmetry of the crystal structure can be found for UTe$_2$, UGe$_2$ similarly for URu$_2$Si$_2$.

  3 citations

• Measurement of Intermittency for Charged Particles in Au + Au Collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7-200 GeV from STAR

  Jin Wu

  SciPost Phys. Proc. 10, 041 (2022) · published 11 August 2022 | Toggle abstract · pdf

  Local density fluctuations near the QCD critical point can be probed by intermittency analysis of scaled factorial moments in relativistic heavy-ion collisions. We report the first measurement of intermittency for charged particles in Au + Au collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7-200 GeV from the STAR experiment at RHIC. We observe scaling behaviors in central Au + Au collisions, with the extracted scaling exponent decreasing from mid-central to the most central Au + Au collisions. Furthermore, the scaling exponent exhibits a non-monotonic energy dependence with a minimum around $\sqrt{s_\mathrm{NN}}$ = 20-30 GeV in central Au + Au collisions.

  3 citations

• The Mu3e experiment

  F. Wauters on behalf of the Mu3e collaboration

  SciPost Phys. Proc. 5, 020 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The \emph{Mu3e} experiment aims for a single event sensitivity of 2$\cdot$10$^{-15}$ on the charged lepton flavour violating $\mu^+\rightarrow e^+ e^+ e^-$ decay. The experimental apparatus, a light-weight tracker based on custom High-Voltage Monolithic Active Pixel Sensors placed in a 1~T magnetic field is currently under construction at the Paul Scherrer Institute, where it will use the full intense 10$^8$ $\mu^+$/s beam available. A final sensitivity of 1$\cdot$10$^{-16}$ is envisioned for a phase II experiment, driving the development of a new high-intensity DC muon source.

  3 citations

• The MSHT20 Parton Distribution Functions

  R.S. Thorne, S. Bailey, T. Cridge, L. Harland-Lang, A.D. Martin

  SciPost Phys. Proc. 8, 018 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from a global analysis of the available hard scattering data and superseding the MMHT14 sets. The parameterisation is now adapted and extended and we include a large number of new data sets: the final HERA and Tevatron data, and a significant number of LHC data sets on vector boson production, inclusive jets and top quark distributions. We include up to NNLO QCD corrections for all data sets that play a major role in the fit. There are some changes to central PDF values and a significant reduction in the uncertainties, but the PDFs and the predictions using them are generally within one standard deviation of the MMHT14 results. We discuss the phenomenological impact of our results.

  3 citations

• On the spin content of the classical massless Rarita-Schwinger system

  Mauricio Valenzuela, Jorge Zanelli

  SciPost Phys. Proc. 14, 047 (2023) · published 24 November 2023 | Toggle abstract · pdf

  We analyze the Rarita-Schwinger massless theory in the Lagrangian and Hamiltonian approaches. At the Lagrangian level, the standard gamma-trace gauge fixing constraint leaves a 1/2 and a 3/2 propagating Poincaré group helicities. At the Hamiltonian level, the result depends on whether the Dirac conjecture is assumed or not. In the affirmative case, a secondary first class constraint is added to the total Hamiltonian and a corresponding gauge fixing condition must be imposed, completely removing the 1/2 sector. In the opposite case, the 1/2 field propagates and the Hamilton field equations match the Euler-Lagrange equations.

  3 citations