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726 results on '"Bucci, Francesca"'

1. The Cauchy–Dirichlet problem for the Moore–Gibson–Thompson equation

Author

Bucci, Francesca and Eller, Matthias

Subjects
Mathematics, QA1-939
Abstract

The Cauchy–Dirichlet problem for the Moore–Gibson–Thompson equation is analyzed. With the focus on non-homogeneous boundary data, two approaches are offered: one is based on the theory of hyperbolic equations, while the other one uses the theory of operator semigroups. This is a mixed hyperbolic problem with a characteristic spatial boundary. Hence, the regularity results exhibit some deficiencies when compared with the non-characteristic case.

Published
2021
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2. Optimal synthesis control for evolution equations subject to nonlocal inputs

Author

Acquistapace, Paolo and Bucci, Francesca

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs, 49N10, 35R09, 93C23, 49N35
Abstract

We consider the linear quadratic (LQ) optimal control problem for a class of evolution equations in infinite dimensions, in the presence of distributed and nonlocal inputs. Following the perspective taken in our previous research work on the LQ problem for integro-differential equations, where the memory term -- here involving the control actions -- is seen as a component of the state, we offer a full (closed-loop, Riccati-like) solution to the optimization problem., Comment: 27 pages

Published
2024

3. Riccati-based solution to the optimal control of linear evolution equations with finite memory

Author

Acquistapace, Paolo and Bucci, Francesca

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs, 49N10, 35R09, 93C23, 49N35
Abstract

In this article we study the optimal control problem with quadratic functionals for a linear Volterra integro-differential equation in Hilbert spaces. With the finite history seen as an (additional) initial datum for the evolution, following the variational approach utilized in the study of the linear-quadratic problem for memoryless infinite dimensional systems, we attain a closed-loop form of the unique optimal control via certain operators that are shown to solve a coupled system of quadratic differential equations. This result provides a first extension to the partial differential equations realm of the Riccati-based theory recently devised by L. Pandolfi in a finite dimensional context., Comment: 41 pages

Published
2023

4. On the infinitesimal generator of an optimal state semigroup

Author

Acquistapace, Paolo and Bucci, Francesca

Subjects
Mathematics - Optimization and Control, 47D03, 93C20, 49N10, 35M33
Abstract

In this article we fully describe the domain of the infinitesimal generator of the optimal state semigroup which arises in the theory of the linear-quadratic problem for a specific class of boundary control systems. This represents an improvement over earlier work of the authors, joint with Lasiecka, where a set inclusion was established, but not an equality. The novel part of the proof of this result developes through appropriate asymptotic estimates that take advantage of the regularity analysis carried out in the study of the optimization problem, while the powers of positive operators and interpolation are still key tools. We also attest to the validity of an assumed relation between two significant parameters in the case of distinct systems of coupled hyperbolic-parabolic partial differential equations which are pertinent to the underlying framework., Comment: 24 pages; minor corrections

Published
2021

5. Uniqueness for Riccati equations with unbounded operator coefficients

Author

Acquistapace, Paolo and Bucci, Francesca

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs, 49N10, 93C20, 35M33
Abstract

In this article we address the issue of uniqueness for differential and algebraic operator Riccati equations, under a distinctive set of assumptions on their unbounded coefficients. The class of boundary control systems characterized by these assumptions encompasses diverse significant physical interactions, all modeled by systems of coupled hyperbolic/parabolic partial differential equations. The proofs of uniqueness provided tackle and overcome the obstacles raised by the peculiar regularity properties of the composite dynamics. These results supplement the theories of the finite and infinite time horizon linear-quadratic problem devised by the authors jointly with Lasiecka, as the unique solution to the Riccati equation enters the closed loop form of the optimal control., Comment: 33 pages, an appendix. The revision pertains almost exclusively to the sections 1.1 and 1.2: historical synopsis expanded, insight into the mathematical proofs slightly amended; minor typos have been fixed

Published
2020

6. Improved boundary regularity for a Stokes-Lam\'e system

Author

Bucci, Francesca

Subjects
Mathematics - Analysis of PDEs, Mathematics - Optimization and Control, 35B65, 35Q74, 35M33, 35Q93, 49N10
Abstract

This paper recalls a partial differential equations system, which is the linearization of a recognized fluid-elasticity interaction three-dimensional model. A collection of regularity results for the traces of the fluid variable on the interface between the body and the fluid is established, in the case a suitable boundary dissipation is present. These regularity estimates -- in time and space, of local and global nature -- are geared toward ensuring the well-posedness of the algebraic Riccati equations which arise from the associated optimal boundary control problems on an infinite time horizon. The theory of operator semigroups and interpolation provide the main tools., Comment: 22 pages

Published
2020

7. The Cauchy-Dirichlet problem for the Moore-Gibson-Thompson equation

Author

Bucci, Francesca and Eller, Matthias

Subjects
Mathematics - Analysis of PDEs, 35B65, 35L35, 35L50, 35R09
Abstract

The Cauchy-Dirichlet problem for the Moore-Gibson-Thompson equation is analyzed. With the focus on non-homogeneous boundary data, two approaches are offered: one is based on the theory of hyperbolic equations, while the other one uses the theory of operator semigroups. This is a mixed hyperbolic problem with a characteristic spatial boundary. Hence, the regularity results exhibit some deficiencies when compared with the non-characteristic case., Comment: 25 pages. A gap in the proof in Section 3 has been fixed, resulting in a modification of the regularity result in the second part of our main theorem. Accepted for publication in C. R. Math. Acad. Sci. Paris

Published
2020

10. Feedback control of the acoustic pressure in ultrasonic wave propagation

Author

Bucci, Francesca and Lasiecka, Irena

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs
Abstract

Classical models for the propagation of ultrasound waves are the Westervelt equation, the Kuznetsov and the Khokhlov-Zabolotskaya-Kuznetsov equations. The Jordan-Moore-Gibson-Thompson equation is a prominent example of a Partial Differential Equation (PDE) model which describes the acoustic velocity potential in ultrasound wave propagation, where the paradox of infinite speed of propagation of thermal signals is eliminated; the use of the constitutive Cattaneo law for the heat flux, in place of the Fourier law, accounts for its being of third order in time. Aiming at the understanding of the fully quasilinear PDE, a great deal of attention has been recently devoted to its linearization -- referred to in the literature as the Moore-Gibson-Thompson equation -- whose mathematical analysis is also of independent interest, posing already several questions and challenges. In this work we consider and solve a quadratic control problem associated with the linear equation, formulated consistently with the goal of keeping the acoustic pressure close to a reference pressure during ultrasound excitation, as required in medical and industrial applications. While optimal control problems with smooth controls have been considered in the recent literature, we aim at relying on controls which are just $L^2$ in time; this leads to a singular control problem and to non-standard Riccati equations. In spite of the unfavourable combination of the semigroup describing the free dynamics that is not analytic, with the challenging pattern displayed by the dynamics subject to boundary control, a feedback synthesis of the optimal control as well as well-posedness of operator Riccati equations are established., Comment: 39 pages; submitted

Published
2018

11. On the regularity of solutions to the Moore-Gibson-Thompson equation: a perspective via wave equations with memory

Author

Bucci, Francesca and Pandolfi, Luciano

Subjects
Mathematics - Analysis of PDEs
Abstract

We undertake a regularity analysis of the solutions to initial/boundary value problems for the (third-order in time) Moore-Gibson-Thompson (MGT) equation. The key to the present investigation is that the MGT equation falls within a large class of systems with memory, with affine term depending on a parameter. For this model equation a regularity theory is provided, which is of also independent interest; it is shown in particular that the effect of boundary data that are square integrable (in time and space) is the same displayed by wave equations. Then, a general picture of the (interior) regularity of solutions corresponding to homogeneous boundary conditions is specifically derived for the MGT equation in various functional settings. This confirms the gain of one unity in space regularity for the time derivative of the unknown, a feature that sets the MGT equation apart from other PDE models for wave propagation. The adopted perspective and method of proof enables us to attain as well the (sharp) regularity of boundary traces., Comment: 26 pages; v2: misprints corrected, Remarks enriched in Section 1

Published
2017

13. Exponential decay properties of a mathematical model for a certain fluid-structure interaction

Author

Avalos, George and Bucci, Francesca

Subjects
Mathematics - Analysis of PDEs, Mathematics - Optimization and Control, 35B35, 35M33, 49J20, 76D07, 49N10
Abstract

In this work, we derive a result of exponential stability for a coupled system of partial differential equations (PDEs) which governs a certain fluid-structure interaction. In particular, a three-dimensional Stokes flow interacts across a boundary interface with a two-dimensional mechanical plate equation. In the case that the PDE plate component is rotational inertia-free, one will have that solutions of this fluid-structure PDE system exhibit an exponential rate of decay. By way of proving this decay, an estimate is obtained for the resolvent of the associated semigroup generator, an estimate which is uniform for frequency domain values along the imaginary axis. Subsequently, we proceed to discuss relevant point control and boundary control scenarios for this fluid-structure PDE model, with an ultimate view to optimal control studies on both finite and infinite horizon. (Because of said exponential stability result, optimal control of the PDE on time interval $(0,\infty)$ becomes a reasonable problem for contemplation.), Comment: 15 pages, 1 figure; submitted

Published
2014

14. Spectral analysis and rational decay rates of strong solutions to a fluid-structure PDE system

Author

Avalos, George and Bucci, Francesca

Subjects
Mathematics - Analysis of PDEs, 35B35, 35M33, 76D07
Abstract

In this paper, we consider the problem of obtaining rational decay for a particular time-evolving fluid-structure model, the type of which has been considered in Chueshov and Ryzhkova (2013). In particular, this partial differential equation (PDE) system is composed of a three-dimensional Stokes flow which evolves within a three dimensional cavity. Moreover, on a (fixed) portion of the cavity wall, $\Omega$ say, a fourth order plate equation is invoked so as to describe the displacements along $\Omega$. Contact between these respective fluid and structure dynamics is established through the boundary interface $\Omega$. Our main result of decay is as follows: The PDE solutions of this fluid-structure PDE, corresponding to smooth initial data, decay at the rate of $O(1/t)$. Our method of proof hinges upon the appropriate invocation of a relatively recent resolvent criterion for rational decays for linear strongly continuous semigroups., Comment: 19 pages, 1 figure

Published
2013

16. A theory of the infinite horizon LQ-problem for composite systems of PDEs with boundary control

Author

Acquistapace, Paolo, Bucci, Francesca, and Lasiecka, Irena

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs, 35M33, 49J20, 93C20
Abstract

We study the infinite horizon Linear-Quadratic problem and the associated algebraic Riccati equations for systems with unbounded control actions. The operator-theoretic context is motivated by composite systems of Partial Differential Equations (PDE) with boundary or point control. Specific focus is placed on systems of coupled hyperbolic/parabolic PDE with an overall `predominant' hyperbolic character, such as, e.g., some models for thermoelastic or fluid-structure interactions. While unbounded control actions lead to Riccati equations with unbounded (operator) coefficients, unlike the parabolic case solvability of these equations becomes a major issue, owing to the lack of sufficient regularity of the solutions to the composite dynamics. In the present case, even the more general theory appealing to estimates of the singularity displayed by the kernel which occurs in the integral representation of the solution to the control system fails. A novel framework which embodies possible hyperbolic components of the dynamics has been introduced by the authors in 2005, and a full theory of the LQ-problem on a finite time horizon has been developed. The present paper provides the infinite time horizon theory, culminating in well-posedness of the corresponding (algebraic) Riccati equations. New technical challenges are encountered and new tools are needed, especially in order to pinpoint the differentiability of the optimal solution. The theory is illustrated by means of a boundary control problem arising in thermoelasticity., Comment: 50 pages, submitted

Published
2012

17. Finite dimensional attractor for a composite system of wave/plate equations with localised damping

Author

Bucci, Francesca and Toundykov, Daniel

Subjects
Mathematics - Dynamical Systems, Mathematics - Analysis of PDEs, 35B41, 35L05, 74K20
Abstract

The long-term behaviour of solutions to a model for acoustic-structure interactions is addressed; the system is comprised of coupled semilinear wave (3D) and plate equations with nonlinear damping and critical sources. The questions of interest are: existence of a global attractor for the dynamics generated by this composite system, as well as dimensionality and regularity of the attractor. A distinct and challenging feature of the problem is the geometrically restricted dissipation on the wave component of the system. It is shown that the existence of a global attractor of finite fractal dimension -- established in a previous work by Bucci, Chueshov and Lasiecka (Comm. Pure Appl. Anal., 2007) only in the presence of full interior acoustic damping -- holds even in the case of localised dissipation. This nontrivial generalization is inspired by and consistent with the recent advances in the study of wave equations with nonlinear localised damping., Comment: 40 pages, 1 figure; v2: added references for Section 1, submitted

Published
2009

18. Regularity of boundary traces for a fluid-solid interaction model

Author

Bucci, Francesca and Lasiecka, Irena

Subjects
Mathematics - Analysis of PDEs, Mathematics - Optimization and Control, 74F10, 35B65, 35B37, 49J20, 49N10
Abstract

We consider a mathematical model for the interactions of an elastic body fully immersed in a viscous, incompressible fluid. The corresponding composite PDE system comprises a linearized Navier-Stokes system and a dynamic system of elasticity; the coupling takes place on the interface between the two regions occupied by the fluid and the solid, respectively. We specifically study the regularity of boundary traces (on the interface) for the fluid velocity field. The obtained trace regularity theory for the fluid component of the system -- of interest in its own right -- establishes, in addition, solvability of the associated optimal (quadratic) control problems on a finite time interval, along with well-posedness of the corresponding operator Differential Riccati equations. These results complement the recent advances in the PDE analysis and control of the Stokes-Lam\'e system., Comment: 20 pages; accepted for publication

Published
2009

19. Optimal boundary control with critical penalization for a PDE model of fluid-solid interactions

Author

Bucci, Francesca and Lasiecka, Irena

Subjects
Mathematics - Optimization and Control, Mathematics - Analysis of PDEs, 35B37, 49J20, 74F10, 49N10, 35B65, 35M20, 93C20.
Abstract

We study the finite-horizon optimal control problem with quadratic functionals for an established fluid-structure interaction model. The coupled PDE system under investigation comprises a parabolic (the fluid) and a hyperbolic (the solid) dynamics; the coupling occurs at the interface between the regions occupied by the fluid and the solid. We establish several trace regularity results for the fluid component of the system, which are then applied to show well-posedness of the Differential Riccati Equations arising in the optimization problem. This yields the feedback synthesis of the unique optimal control, under a very weak constraint on the observation operator; in particular, the present analysis allows general functionals, such as the integral of the natural energy of the physical system. Furthermore, this work confirms that the theory developed in Acquistapace et al. [Adv. Differential Equations, 2005] -- crucially utilized here -- encompasses widely differing PDE problems, from thermoelastic systems to models of acoustic-structure and, now, fluid-structure interactions., Comment: 22 pages, submitted; v2: misprints corrected, a remark added in section 2

Published
2009

20. Riccati-based solution to the optimal control of linear evolution equations with finite memory.

Author

Acquistapace, Paolo and Bucci, Francesca

Subjects
PARTIAL differential equations, INTEGRO-differential equations, DIFFERENTIAL equations, LINEAR equations, QUADRATIC differentials, OPTIMAL control theory, EVOLUTION equations
Abstract

In this article we study the optimal control problem with quadratic functionals for a linear Volterra integro-differential equation in Hilbert spaces. With the finite history seen as an (additional) initial datum for the evolution, following the variational approach utilized in the study of the linear-quadratic problem for memoryless infinite dimensional systems, we attain a closed-loop form of the unique optimal control via certain operators that are shown to solve a coupled system of quadratic differential equations. This result provides a first extension to the partial differential equations realm of the Riccati-based theory recently devised by L. Pandolfi in a finite dimensional context. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Long-time dynamics of a coupled system of nonlinear wave and thermoelastic plate equations

Author

Bucci, Francesca and Chueshov, Igor

Subjects
Mathematics - Analysis of PDEs, Mathematics - Dynamical Systems, 37L30, 35M20, 74H40
Abstract

We prove the existence of a compact, finite dimensional, global attractor for a coupled PDE system comprising a nonlinearly damped semilinear wave equation and a nonlinear system of thermoelastic plate equations, without any mechanical (viscous or structural) dissipation in the plate component. The plate dynamics is modelled following Berger's approach; we investigate both cases when rotational inertia is included into the model and when it is not. A major part in the proof is played by an estimate--known as stabilizability estimate--which shows that the difference of any two trajectories can be exponentially stabilized to zero, modulo a compact perturbation. In particular, this inequality yields bounds for the attractor's fractal dimension which are independent of two key parameters, namely $\gamma$ and $\kappa$, the former related to the presence of rotational inertia in the plate model and the latter to the coupling terms. Finally, we show the upper semi-continuity of the attractor with respect to these parameters., Comment: 38 pages. To appear in: Discrete Contin. Dyn. Syst. Series A

Published
2008

22. Search for $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Petrov, Yevgeniy, Wong, Vincent Wai Sum, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Tinti, Gemma, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Fiorenza, Renato, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, d'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Cretaro, Paolo, Turisini, Matteo, Frezza, Ottorino, Ammendola, Roberto, Bonaiuto, Vincenzo, de Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Andrey, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Tomczak, Adam, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, Rubin, Philip David, Hives, Zdenko, Akmete, Atakan Tugberk, Soldani, Mattia, Bandiera, Laura, Mazzolari, Andrea, Romagnoni, Marco, Sytov, Alexei, Panichi, Ilaria, Lo Chiatto, Prisco, d'Errico, Mariaelena, Giordano, Raffaele, Briano Olvera, Alejandro, Reyes Santos, Marco Antonio, Boboc, Petre, Kereibay, Dias, Gorshanov, Konstantin, Okhotnikov, Artem, Sadovskiy, Alexander, Sanders, Jack, Kenworthy, Chandler, de Martino, Bianca, Rosa, Ilaria, Ceoletta, Marco, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and NA62

Subjects
pair production, CERN Lab, quantum chromodynamics, axion, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], anomaly, mediation, branching ratio, hidden sector, NA62, Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

The first search for ultra-rare $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of $1.4\times 10^{-8}$ at 90% CL is obtained for the branching ratio of the $K^+\to\pi^+e^+e^-e^+e^-$ decay, predicted in the Standard Model to be $(7.2\pm0.7)\times 10^{-11}$. Upper limits at 90% CL are obtained at the level of $10^{-9}$ for the branching ratios of two prompt decay chains involving pair-production of hidden-sector mediators: $K^+\to\pi^+aa$, $a\to e^+e^-$ and $K^+\to\pi^+S$, $S\to A^\prime A^\prime$, $A^\prime\to e^+e^-$. The QCD axion is excluded as a possible explanation of the "17 MeV anomaly"., Comment: Version to be submitted to Physics Letters B

Published
2023

25. A study of the $K^+ \to \pi^0 e^+ \nu \gamma$ decay

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Petrov, Yevgeniy, Wong, Vincent Wai Sum, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Tinti, Gemma, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Fiorenza, Renato, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Cretaro, Paolo, Turisini, Matteo, Frezza, Ottorino, Ammendola, Roberto, Bonaiuto, Vincenzo, De Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Tomczak, Adam, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, Rubin, Philip David, Hives, Zdenko, Akmete, Atakan Tugberk, Soldani, Mattia, Bandiera, Laura, Mazzolari, Andrea, Romagnoni, Marco, Sytov, Alexei, Panichi, Ilaria, Lo Chiatto, Prisco, D'Errico, Mariaelena, Giordano, Raffaele, Briano Olvera, Alejandro, Reyes Santos, Marco Antonio, Boboc, Petre, Kereibay, Dias, Gorshanov, Konstantin, Okhotnikov, Artem, Sadovskiy, Alexander, and Sanders, Jack

Subjects
Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

A sample of $1.3 \times 10^5 K^+ \to \pi^0 e^+ \nu \gamma$ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017-2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. An asymmetry, possibly related to T-violation, is investigated with no evidence observed within the achieved precision. A sample of $1.3 \times 10^5$$K^+ \to \pi^0 e^+ \nu \gamma$ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017-2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. An asymmetry, possibly related to T-violation, is investigated with no evidence observed within the achieved precision.

Published
2023

27. Improved calorimetric particle identification in NA62 using machine learning techniques

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Petrov, Yevgeniy, Wong, Vincent Wai Sum, Yu, Mengda, Fedorko, Wojciech, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Tinti, Gemma, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Fiorenza, Renato, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Cretaro, Paolo, Turisini, Matteo, Frezza, Ottorino, Ammendola, Roberto, Bonaiuto, Vincenzo, De Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Tomczak, Adam, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, Rubin, Philip David, Hives, Zdenko, Akmete, Atakan Tugberk, Soldani, Mattia, Bandiera, Laura, Mazzolari, Andrea, Romagnoni, Marco, Sytov, Alexei, Panichi, Ilaria, Lo Chiatto, Prisco, D'Errico, Mariaelena, Giordano, Raffaele, Briano Olvera, Alejandro, Reyes Santos, Marco Antonio, Boboc, Petre, Kereibay, Dias, Gorshanov, Konstantin, Okhotnikov, Artem, Sadovskiy, Alexander, and Sanders, Jack

Subjects
High Energy Physics - Experiment (hep-ex), Physics - Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

Measurement of the ultra-rare $K^+\to\pi^+\nu\bar\nu$ decay at the NA62 experiment at CERN requires high-performance particle identification to distinguish muons from pions. Calorimetric identification currently in use, based on a boosted decision tree algorithm, achieves a muon misidentification probability of $1.2\times 10^{-5}$ for a pion identification efficiency of 75% in the momentum range of 15-40 GeV/$c$. In this work, calorimetric identification performance is improved by developing an algorithm based on a convolutional neural network classifier augmented by a filter. Muon misidentification probability is reduced by a factor of six with respect to the current value for a fixed pion-identification efficiency of 75%. Alternatively, pion identification efficiency is improved from 72% to 91% for a fixed muon misidentification probability of $10^{-5}$., Comment: Updated author list and Ref. 4

Published
2023
Full Text
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28. A search for the $K^+ \to \mu^- \nu e^+ e^+$ decay

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Petrov, Yevgeniy, Wong, Vincent Wai Sum, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Tinti, Gemma, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Fiorenza, Renato, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, d'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Cretaro, Paolo, Turisini, Matteo, Frezza, Ottorino, Ammendola, Roberto, Bonaiuto, Vincenzo, de Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Tomczak, Adam, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, Rubin, Philip David, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and NA62

Subjects
flavor, CERN Lab, lepton, conservation law, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], lepton number, branching ratio, NA62, Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

A search for the $K^+\to\mu^-\nu e^+e^+$ decay, forbidden within the Standard Model by either lepton number or lepton flavour conservation depending on the flavour of the emitted neutrino, has been performed using the dataset collected by the NA62 experiment at CERN in 2016--2018. An upper limit of $8.1\times 10^{-11}$ is obtained for the decay branching fraction at 90% CL, improving by a factor of 250 over the previous search., Comment: Final version, accepted for publication in Physics Letters B

Published
2022

29. A measurement of the $K^+ \to \pi^+ \mu^+ \mu^-$ decay

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, J., Numao, Toshio, Petrov, Yevgeniy, Wong, Vincent Wai Sum, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Potrebenikov, Yu., Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Tinti, Gemma, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Fiorenza, Renato, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, d'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Cretaro, Paolo, Turisini, Matteo, Frezza, Ottorino, Ammendola, Roberto, Bonaiuto, Vincenzo, de Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Tomczak, Adam, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, Rubin, Philip David, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and NA62

Subjects
Fixed Target Experiments, data analysis method, background, Flavour Changing Neutral Currents, perturbation theory: chiral, dimuon: mass spectrum, CERN SPS, pi+, mass dependence, NA62, High Energy Physics - Experiment, muon: pair production, K+: semileptonic decay, +pi%2B+muon%2B+muon%22">K+ --> pi+ muon+ muon, branching ratio: measured, Rare Decay, K+: branching ratio, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], decay: form factor, Branching fraction, K+: secondary beam, Particle Physics - Experiment, K: form factor, experimental results
Abstract

A sample of $2.8 \times 10^4$ $K^{+} \to \pi^{+} \mu^{+} \mu^{-}$ candidates with negligible background was collected by the NA62 experiment at the CERN SPS in 2017--2018. The model-independent branching fraction is measured to be $(9.15 \pm 0.08)\times 10^{-8}$, a factor three more precise than previous measurements. The decay form factor is presented as a function of the squared dimuon mass. A measurement of the form factor parameters and their uncertainties is performed using a description based on Chiral Perturbation Theory at $\mathcal{O}(p^6)$., Comment: 17 pages, 5 figures. Updated version (6 October 2022) accepted for publication in JHEP

Published
2022

30. Measurement of the very rare $K^+ \to \pi^+ \nu \bar\nu$ decay

Author

Zamkovský, Michal, primary, Aliberti, Riccardo, additional, Ambrosino, F., additional, Ammendola, Roberto, additional, ANGELUCCI, Bruno, additional, Antonelli, A., additional, Anzivino, G, additional, Arcidiacono, Roberta, additional, Bache, T., additional, Baeva, Aigul, additional, Baigarashev, D., additional, Barbanera, M., additional, Bernhard, J., additional, Biagioni, A., additional, Bician, Lubos, additional, Biino, Cristina, additional, Bizzeti, Andrea, additional, Blazek, T., additional, BlochDevaux, Brigitte, additional, Bonaiuto, V., additional, Boretto, M., additional, Bragadireanu, M., additional, Britton, D., additional, Brizioli, Francesco, additional, Brunetti, M.B., additional, Bryman, D., additional, Bucci, Francesca, additional, Capussela, Tiziana, additional, Carmignani, J., additional, Ceccucci, Augusto, additional, Cenci, P., additional, Cerny, V., additional, Cerri, C., additional, Checcucci, B., additional, Conovaloff, A., additional, Cooper, P., additional, Cortina Gil, Eduardo, additional, Corvino, M., additional, Costantini, F., additional, Cotta Ramusino, Angelo, additional, Coward, A., additional, D’Agostini, G., additional, Dainton, John, additional, Dalpiaz, P., additional, Danielsson, Hans, additional, De Simone, N., additional, Di Filippo, D., additional, Di Lella, Luigi, additional, Doble, Niels, additional, Dobrich, Babette, additional, Duval, F., additional, Duk, V., additional, Emelyanov, D., additional, Engelfried, Jurgen, additional, Enik, T., additional, Estrada-Tristan, Nora, additional, Falaleev, Valeri, additional, Fantechi, R., additional, Fascianelli, V., additional, Federici, Luca, additional, Fedotov, S., additional, Filippi, Alessandra, additional, Fiorini, Massimiliano, additional, Fry, J., additional, Fu, J., additional, Fucci, Adolfo, additional, Fulton, L., additional, Gamberini, Enrico, additional, Gatignon, Lau, additional, Georgiev, G., additional, Ghinescu, S., additional, Gianoli, Alberto, additional, Giorgi, M., additional, Giudici, Sergio, additional, Gonnella, Francesco, additional, Goudzovski, Evgueni, additional, Graham, C., additional, Guida, Roberto, additional, Gushchin, Evgeny, additional, Hahn, F., additional, Heath, H., additional, Henshaw, J., additional, Holzer, E.B., additional, Husek, Tomas, additional, Hutanu, O., additional, Hutchcroft, D., additional, Iacobuzio, L., additional, Iacopini, Enrico, additional, Imbergamo, Ermanno, additional, Jenninger, B., additional, Jerhot, Jan, additional, Jones, R.W., additional, Kampf, K., additional, Kekelidze, Vladimir, additional, Kholodenko, Sergei, additional, Khoriauli, G., additional, Khotyantsev, A., additional, Kleimenova, Alina, additional, Korotkova, A., additional, Koval, Michal, additional, Kozhuharov, Venelin, additional, Kucerova, Zuzana, additional, Kudenko, Y., additional, Kunze, J., additional, Kurochka, V., additional, Kurshetsov, V., additional, Lanfranchi, Gaia, additional, Lamanna, Gianluca, additional, Lari, E., additional, Latino, G., additional, Laycock, Paul, additional, Lazzeroni, Cristina, additional, Lenti, M., additional, Lehmann Miotto, G., additional, Leonardi, E., additional, Lichard, P., additional, Litov, Leandar, additional, Lollini, R., additional, Lomidze, D., additional, Lonardo, Alessandro, additional, Lubrano, Pasquale, additional, Lupi, Matteo, additional, Lurkin, N., additional, Madigozhin, Dmitry, additional, Mannelli, I., additional, Mapelli, Alessandro, additional, Marchetto, Flavio, additional, Marchevski, Radoslav, additional, Martellotti, S., additional, Massarotti, Paolo, additional, Massri, Karim, additional, Maurice, E., additional, Medvedeva, M., additional, Mefodev, A., additional, Menichetti, E., additional, Migliore, Ernesto, additional, Minucci, E., additional, Mirra, M., additional, Misheva, M., additional, Molokanova, Natalia, additional, Moulson, Matthew, additional, Movchan, S., additional, Napolitano, M., additional, Neri, I., additional, Newson, F., additional, Norton, Alan, additional, Noy, Matthew, additional, Numao, Toshio, additional, Obraztsov, Vladimir, additional, Ostankov, A., additional, Padolski, S., additional, Page, R., additional, Palladino, V., additional, Parenti, A., additional, Parkinson, Chris John, additional, Pedreschi, E., additional, Pepe, Monica, additional, Perrin-Terrin, M., additional, Peruzzo, L., additional, Petrov, P., additional, Petrov, Y., additional, Petrucci, Ferruccio, additional, Piandani, Roberto, additional, Piccini, M., additional, Pinzino, Jacopo, additional, Polenkevich, I., additional, Pontisso, L., additional, Potrebenikov, Yuri, additional, Protopopescu, D., additional, Raggi, Mauro, additional, Romano, Angela, additional, Rubin, P., additional, Ruggiero, Giuseppe, additional, Ryjov, Vladimir, additional, Salamon, A., additional, Santoni, C., additional, Saracino, G., additional, Sargeni, F., additional, Schuchmann, S., additional, Semenov, Vitali, additional, Sergi, Antonino, additional, Shaikhiev, A., additional, Shkarovskiy, Sergey, additional, Soldi, D., additional, Sugonyaev, V., additional, Sozzi, M., additional, Spadaro, T., additional, Spinella, F., additional, Sturgess, A., additional, Swallow, Joel, additional, Trilov, Stoyan Miroslavov, additional, Valente, Paolo, additional, Velghe, Bob, additional, Venditti, Stefano, additional, Vicini, P., additional, Volpe, Roberta, additional, Vormstein, M., additional, Wahl, Heinrich, additional, Wanke, Rainer, additional, Wrona, B., additional, Yushchenko, O., additional, and Zinchenko, A., additional

Published
2022
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38. Search for lepton number and flavour violation in $K^+ $ and $\pi^0$ decays

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Potrebenikov, Yu., Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Petrov, Yevgeniy, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Ammendola, Roberto, Bonaiuto, Vincenzo, De Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Henshaw, Jack, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, and Rubin, Philip David

Subjects
High Energy Physics::Phenomenology, High Energy Physics::Experiment, Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

Searches for the lepton number violating $K^{+} \rightarrow \pi^{-} \mu^{+} e^{+}$ decay and the lepton flavour violating $K^{+} \rightarrow \pi^{+} \mu^{-} e^{+}$ and $\pi^{0} \rightarrow \mu^{-} e^{+}$ decays are reported using data collected by the NA62 experiment at CERN in $2017$-$2018$. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: $\mathcal{B}(K^{+}\rightarrow\pi^{-}\mu^{+}e^{+}), Comment: 8 pages, 4 figures

Published
2021

41. Texture enhanced Statistical Region Merging with application to automatic knee bones segmentation from CT

Author

Zhou, Jun, Salvado, Olivier, Sohel, Ferdous, Borges, Paulo Vinicius K., Wang, Shilin, Howes, Michael, Bajger, Mariusz, Lee, Gobert, Bucci, Francesca, Martelli, Saulo, Zhou, Jun, Salvado, Olivier, Sohel, Ferdous, Borges, Paulo Vinicius K., Wang, Shilin, Howes, Michael, Bajger, Mariusz, Lee, Gobert, Bucci, Francesca, and Martelli, Saulo

Abstract

Statistical Region Merging technique belongs to the portfolio of very successful image segmentation methods across diverse domains and applications. The method is based on a solid probabilistic principle and was extended in various directions to suit specific applications, including those from medical domains. In its basic implementation the technique is based on a merging criterion relying on image pixel intensities. Sufficient to segment well some natural scene images, it often deteriorates dramatically when challenging medical images are segmented. In this study we introduce a new merging criterion into the method which utilizes texture characteristic of the image. We demonstrate that the enhanced criterion allows segmentation of knee bones in CT comparable to state-of-the-art outcomes found in literature while preserving the desirable properties of the original technique.

Published
2021

44. An investigation of the very rare $K^+\rightarrow\pi^+\nu\bar{\nu}$ decay

Author

Cortina Gil, Eduardo, Minucci, Elisa, Padolski, Sergey, Petrov, Plamen, Velghe, Bob, Bryman, Douglas, Fu, Ji, Numao, Toshio, Husek, Tomas, Kampf, Karol, Zamkovsky, Michal, Jerhot, Jan, Aliberti, Riccardo, Khoriauli, Gia, Kunze, Jonas, Lomidze, David, Marchevski, Radoslav, Peruzzo, Letizia, Vormstein, Mario, Wanke, Rainer, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Ilaria, Norton, Alan, Petrucci, Ferruccio, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, Martellotti, Silvia, Moulson, Matthew, Kozhuharov, Venelin, Litov, Leandar, Georgiev, Georgi, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Capussela, Tiziana, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Lollini, Riccardo, Santoni, Cristiano, Brizioli, Francesco, Barbanera, Mattia, Cenci, Patrizia, Checcucci, Bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, Lubrano, Pasquale, Costantini, Flavio, Doble, Niels, Giorgi, Marcello, Giudici, Sergio, Lari, Enrico, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, Mannelli, Italo, Cerri, Claudio, Fantechi, Riccardo, Pedreschi, Elena, Piandani, Roberto, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Ammendola, Roberto, Bonaiuto, Vincenzo, De Simone, Nicola, Federici, Luca, Fucci, Adolfo, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Iacobuzio, Lorenza, Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jürgen, Estrada-Tristan, Nora, Bragadireanu, Alexandru Mario, Ghinescu, Stefan Alexandru, Hutanu, Ovidiu Emanuel, Enik, Temur, Falaleev, Valeri, Kekelidze, Vladimir, Korotkova, Anna, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Polenkevich, Irina, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Baeva, Aigul, Baigarashev, Dosbol, Emelyanov, Dmitry, Fedotov, Sergei, Khotyantsev, Alexey, Gushchin, Evgeny, Kleimenova, Alina, Kudenko, Yury, Kurochka, Viktoriia, Medvedeva, Mariia, Mefodev, Aleksandr, Shaikhiev, Artur, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Ostankov, Aleksandr, Semenov, Vitali, Sugonyaev, Valentin, Yushchenko, Oleg, Bician, Lubos, Blazek, Tomas, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Danielsson, Hans, Döbrich, Babette, Duval, Francois, Gatignon, Lau, Guida, Roberto, Hahn, Ferdinand, Holzer, Eva Barbara, Jenninger, Berthold, Laycock, Paul, Lehmann Miotto, Giovanna, Lichard, Peter, Mapelli, Alessandro, Noy, Matthew, Palladino, Vito, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Ryjov, Vladimir, Schuchmann, Simone, Venditti, Stefano, Brunetti, Maria Brigida, Bache, Thomas, Goudzovski, Evgueni, Lazzeroni, Cristina, Fascianelli, Valeria, Lurkin, Nicolas, Newson, Francis, Parkinson, Christopher, Romano, Angela, Sergi, Antonino, Sturgess, Andrew, Swallow, Joel, Heath, Helen, Page, Ryan, Trilov, Stoyan, Angelucci, Bruno, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger William Lewis, Dainton, John Bourke, Fry, John Richard, Fulton, Liam, Hutchcroft, David, Carmignani, Joseph, Massri, Karim, Maurice, Emilie, Wrona, Bozydar, Conovaloff, Adam, Cooper, Peter, Coward, David, and Rubin, Philip David

Subjects
hep-ex, Particle Physics - Experiment, High Energy Physics - Experiment
Abstract

A search for heavy neutral lepton (N) production in $K^+\rightarrow\pi^+\nu\bar{\nu}$ decays using the data sample collected by the NA62 experiment at CERN in 2017–2018 is reported. Upper limits of the extended neutrino mixing matrix element $|U_{e4}|^2$ are established at the level of $10^{−9}$ over most of the accessible heavy neutral lepton mass range 144–462 MeV/$c^2$, with the assumption that the lifetime exceeds 50 ns. These limits improve significantly upon those of previous production and decay searches. The $|U_{e4}|^2$ range favoured by Big Bang Nucleosynthesis is excluded up to a mass of about 340 MeV/$c^2$. The NA62 experiment reports an investigation of the $ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $ mode from a sample of K$^{+}$ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of (0.389 ± 0.024) × 10$^{−10}$, corresponding to 2.2 events assuming the Standard Model branching ratio of (8.4 ± 1.0) × 10$^{−11}$. Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1.78 × 10$^{−10}$ for the $ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $ branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of ($ {0.48}_{-0.48}^{+0.72} $) × 10$^{−10}$, are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements. The NA62 experiment reports an investigation of the $K^+\rightarrow\pi^+\nu\bar{\nu}$ mode from a sample of $K^+$ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of $(0.389\pm 0.024)\times10^{-10}$, corresponding to 2.2 events assuming the Standard Model branching ratio of $(8.4\pm1.0)\times10^{-11}$. Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of $1.78\times10^{-10}$ for the $K^+\rightarrow\pi^+\nu\bar{\nu}$ branching ratio at 90\%\,CL. This, together with the corresponding 68\%\,CL measurement of $(0.48^{+0.72 }_{-0.48})\times10^{-10}$, are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.

Published
2020

46. Searches for lepton number violating $K^+$ decays

Author

Cortina Gil, Eduardo, Velghe, Bob, Bryman, Douglas, Husek, Tomas, Kampf, Karol, Marchevski, Radoslav, Wanke, Rainer, Cotta Ramusino, Angelo, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Igor, Petrucci, Ferruccio, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Parenti, Andrea, Volpe, Roberta, Antonelli, Antonella, Gonnella, Francesco, Lamanna, Gianluca, Lanfranchi, Gaia, David Moulson, Matthew, Kozhuharov, Venelin, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Corvino, Michele, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Lollini, Riccardo, Santoni, Cristiano, Barbanera, Mattia, Cenci, Patrizia, checcucci, bruno, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, lubrano, pasquale, Costantini, Flavio, GIORGI, MARCELLO., Giudici, Sergio, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, Di Lella, Luigi, mannelli, italo, Fantechi, Riccardo, Pedreschi, Elena, piandani, roberto, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Ammendola, Roberto, Bonaiuto, Vincenzo, Federici, Luca, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Boretto, Marco, Filippi, Alessandra, Pietro Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Engelfried, Jurgen, Patricia Estrada Tristan, Nora, Zinchenko, Alexander, Gushchin, Evgeny, Shaikhiev, Artur, Bician, Lubos, Cerny, Vladimir, Koval, Michal, Kucerova, Zuzana, Ceccucci, Augusto, Bernhard, Johannes, Döbrich, Babette, Gatignon, Lau, Laycock, Paul, Mapelli, Alessandro, Perrin-Terrin, Mathieu, Ruggiero, Giuseppe, Goudzovski, Evgueni, Lurkin, Nicolas, Sergi, Antonino, Heath, Helen, Britton, David, Protopopescu, Dan, Graham, Connor, Jones, Roger, Fry, John, Massri, Karim, Coward, David, and Rubin, Philip

Abstract

The NA62 experiment at CERN reports a search for the lepton number violating decays K+→π−e+e+ and K+→π−μ+μ+ using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2×10−10 and 4.2×10−11 are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively.

Published
2019

48. Search for heavy neutral lepton production in K+ decays

Author

Husek, Tomas, Kampf, Karol, Cotta Ramusino, Angelo, Fiorini, Massimiliano, Gamberini, Enrico, Gianoli, Alberto, Neri, Igor, Petrucci, Ferruccio, Bizzeti, Andrea, Bucci, Francesca, Iacopini, Enrico, Latino, Giuseppe, Lenti, Massimo, Volpe, Roberta, antonelli, antonella, Lamanna, Gianluca, Lanfranchi, Gaia, David Moulson, Matthew, Raggi, Mauro, Spadaro, Tommaso, Ambrosino, Fabio, Di Filippo, Domenico, Massarotti, Paolo, Mirra, Marco, Napolitano, Marco, Saracino, Giulio, Anzivino, Giuseppina, Santoni, Cristiano, Barbanera, Mattia, Cenci, Patrizia, Duk, Viacheslav, Lupi, Matteo, Pepe, Monica, Piccini, Mauro, lubrano, pasquale, Costantini, Flavio, GIORGI, MARCELLO., Giudici, Sergio, Pinzino, Jacopo, Pontisso, Luca, Sozzi, Marco, mannelli, italo, Fantechi, Riccardo, Spinella, Franco, Biagioni, Andrea, D'Agostini, Giulio, Leonardi, Emanuele, Lonardo, Alessandro, Valente, Paolo, Vicini, Piero, Ammendola, Roberto, Bonaiuto, Vincenzo, Federici, Luca, Salamon, Andrea, Sargeni, Fausto, Arcidiacono, Roberta, Biino, Cristina, Bloch-Devaux, Brigitte, Filippi, Alessandra, Pietro Marchetto, Flavio, Menichetti, Ezio, Migliore, Ernesto, Soldi, Dario, Zinchenko, Alexander, Gushchin, Evgeny, D'Albrich, Babette, Lurkin, Nicolas, Sergi, Antonino, Heath, Helen, Fry, John, Massri, Karim, NA62 Collaboration, Angelucci, Bruno, Britton, David, and Protopopescu, Dan

Subjects
Nuclear Experiment
Abstract

A search for heavy neutral lepton production in K + decays using a data sample collected with a minimum\ud bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level\ud are established on the elements of the extended neutrino mixing matrix |Ue4|\ud 2 and |Uμ4|\ud 2 for heavy\ud neutral lepton mass in the ranges 170–448 MeV/c2 and 250–373 MeV/c2, respectively. This improves on\ud the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 and\ud above 300 MeV/c2 for |Uμ4|2.

Published
2018

50. Search for heavy neutrinos in $K^+ \rightarrow \mu^+ \nu_{\mu}$ decays

Author

Lazzeroni, Cristina, Lurkin, Nicolas, Newson, Francis, Romano, Angela, Ceccucci, Augusto, Danielsson, Hans, Falaleev, Valeri, Gatignon, Lau, Goy Lopez, Silvia, Hallgren, Bjorn, Maier, Andrew, Peters, Andreas Joachim, Piccini, Mauro, Riedler, Petra, Frabetti, Pierluigi, Gersabeck, Evelina Mihova, Kekelidze, Vladimir, Madigozhin, Dmitry, Misheva, Milena, Molokanova, Natalia, Movchan, Sergei, Potrebenikov, Yuri, Shkarovskiy, Sergey, Zinchenko, Alexander, Rubin, Philip David, Baldini, Wander, Cotta Ramusino, Angelo, Dalpiaz, Pietro, Fiorini, Massimiliano, Gianoli, Alberto, Norton, Alan, Petrucci, Ferruccio, Savrié, Mauro, Wahl, Heinrich, Bizzeti, Andrea, Bucci, Francesca, Veltri, Michele, Iacopini, Enrico, Lenti, Massimo, Antonelli, Antonella, Moulson, Matthew, Raggi, Mauro, Spadaro, Tommaso, Eppard, Kirsten, Hita-Hochgesand, Manuel, Kleinknecht, Konrad, Renk, Burkhard, Wanke, Rainer, Winhart, Andreas, Winston, Roland, Bolotov, Vladimir, Duk, Viacheslav, Gushchin, Evgeny, Ambrosino, Fabio, Di Filippo, Domenico, Massarotti, Paolo, Napolitano, Marco, Palladino, Vito, Saracino, Giulio, Anzivino, Giuseppina, Imbergamo, Ermanno, Piandani, Roberto, Sergi, Antonino, Cenci, Patrizia, Pepe, Monica, Costantini, Flavio, Doble, Niels, Giudici, Sergio, Pierazzini, Giuseppe, Sozzi, Marco, Venditti, Stefano, Balev, Spasimir, Collazuol, Gianmaria, Di Lella, Luigi, Gallorini, Stefano, Goudzovski, Evgueni, Lamanna, Gianluca, Mannelli, Italo, Ruggiero, Giuseppe, Cerri, Claudio, Fantechi, Riccardo, Kholodenko, Sergey, Kurshetsov, Viktor, Obraztsov, Vladimir, Semenov, Vitali, Yushchenko, Oleg, D'Agostini, Giulio, Leonardi, Emanuele, Serra, Marco, Valente, Paolo, Fucci, Adolfo, Salamon, Andrea, Bloch-Devaux, Brigitte, Peyaud, Bernard, Engelfried, Jürgen, Coward, David, Kozhuharov, Venelin, Litov, Leandar, Arcidiacono, Roberta, Bifani, Simone, Biino, Cristina, Dellacasa, Giulio, Marchetto, Flavio, Numao, Toshio, Retière, Fabrice, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, NA62, Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay

Subjects
new physics, hep-ex, neutrino: heavy: search for, K+: rare decay, High Energy Physics::Phenomenology, muon+: energy spectrum, mass: upper limit, NA62, High Energy Physics - Experiment, mass spectrum, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], +muon%2B+neutrino%2Fmu%22">K+ --> muon+ neutrino/mu, Heavy neutrinos, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], High Energy Physics::Experiment, Kaon decays, K+: leptonic decay, neutrino: mass, S077A01, neutrino: mixing, missing-mass, Particle Physics - Experiment, experimental results
Abstract

The NA62 experiment recorded a large sample of $K^+ \rightarrow \mu^+ \nu_{\mu}$ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range $2 \times 10^{-6}$ to $10^{-5}$ have been set on the squared mixing matrix element $|U_{\mu4} |^2$ between muon and heavy neutrino states, for heavy neutrino masses in the range 300-375 MeV/$c^2$. The result extends the range of masses for which upper limits have been set on the value of $|U_{\mu4} |^2$ in previous production search experiments., Comment: 12 pages, 8 figures. Published in Physics Letters B

Published
2017

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