Dib Venturelli, Claudio Omar

2005-08-01, Riquelme, M., Reisenegger, A., Espinosa, O., Dib Venturelli, Claudio Omar

Magnetars are a subclass of neutron stars whose intense soft-gamma-ray bursts and quiescent X-ray emission are believed to be powered by the decay of a strong internal magnetic field. We reanalyze neutrino emission in such stars in the plausibly relevant regime in which the Landau band spacing $\Delta E$ of both protons and electrons is much larger than kT (where k is the Boltzmann constant and T is the temperature), but still much smaller than the Fermi energies. Focusing on the direct Urca process, we find that the emissivity oscillates as a function of density or magnetic field, peaking when the Fermi level of the protons or electrons lies about $\sim$3 kT above the bottom of any of their Landau bands. The oscillation amplitude is comparable to the average emissivity when $\Delta E$ is roughly the geometric mean of kT and the Fermi energy (excluding mass), i.e., at fields much weaker than required to confine all particles to the lowest Landau band. Since the density and magnetic field strength vary continuously inside the neutron star, there will be alternating surfaces of high and low emissivity. Globally, these oscillations tend to average out, making it unclear whether there will be any observable effects.

2019-03-25, Ahdida, C., Albanese, R., Alexandrov, A., Anokhina, A., Aoki, S., Arduini, G., Atkin, E., Azorskiy, N., Back, J. J., Bagulya, A., Santos, F. Baaltasar Dos, Baranov, A., Bardou, F., Barker, G. J., Battistin, M., Bauche, J., Bay, A., Bayliss, V., Bencivenni, G., Berdnikov, A. Y., Berdnikov, Y. A., Berezkina, I., Bertani, M., Betancourt, C., Bezshyiko, I., Bezshyyko, O., Bick, D., Bieschke, S., Blanco, A., Boehm, J., Bogomilov, M., Bondarenko, K., Bonivento, W. M., Borburgh, J., Boyarsky, A., Brenner, R., Breton, D., Brundler, R., Bruschi, M., Büscher, V., Buonaura, A., Buontempo, S., Cadeddu, S., Calcaterra, A., Calviani, M., Campanelli, M., Casolino, M., Charitonidis, N., Chau, P., Chauveau, J., Chepurnov, A., Chernyavskiy, M., Choi, K. Y., Chumakov, A., Ciambrone, P., Cornelis, K., Cristinziani, M., Crupano, A., Dallavalle, G. M., Datwyler, A., D'ambrosio, N., D'appollonio, G., Saraiva, J. De Carvalho, Lellis, G. De, De Magistris, M., Roeck, A. De, De Serio, M., De Simone, D., Dedenko, L., Dergachev, P., Di Crescenzo, A., Di Marco, N., Dib Venturelli, Claudio Omar, Dmitrievskiy, S., Dougherty, L. A., Dolmatov, A., Domenici, D., Donskov, S., Drohan, V., Dubreuil, A., Ebert, J., Enik, T., Etenko, A., Fabbri, F., Fabbri, L., Fabich, A., Fedin, O., Fedotovs, F., Felici, G., Ferro-Luzzi, M., Filippov, K., Fini, R. A., Fonte, P., Franco, C., V. Lyubovitskij, Kovalenko, Sergey, Froeschl, R.

The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV c proton beam offers a unique opportunity to explore the Hidden Sector [1–3]. The proposed experiment is an intensity frontier experiment which is capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. The high-intensity experimental facility developed by the SHiP Collaboration is based on a number of key features and developments which provide the possibility of probing a large part of the parameter space for a wide range of models with light long-lived superweakly interacting particles with masses up to O¹10º GeV c2 in an environment of extremely clean background conditions. This paper describes the proposal for the experimental facility together with the most important feasibility studies. The paper focuses on the challenging new ideas behind the beam extraction and beam delivery, the proton beam dump, and the suppression of beam-induced background.

2024-06-01, Ahdida, C., Akmete, A., Bieschke, S., Borburgh, J., Chumakov, A., Cornelis, K., D’Ambrosio, N., D’Appollonio, G., de Asmundis, R., De Carvalho Saraiva, J., Di Giulio, L., Dib Venturelli, Claudio Omar, Dijkstra, H., Dougherty, L. A., Drohan, V., Durhan, O., Ehlert, M., Elikkaya, E., Graverini, E., Grenard, J. L., Hakobyan, Hayk, Kovalenko, Sergey, Lyubovitskij, V.

AbstractThe SHiP-charm project was proposed to measure the associated charm production induced by 400 GeV/c protons in a thick target, including the contribution from cascade production. An optimisation run was performed in July 2018 at CERN SPS using a hybrid setup. The high resolution of nuclear emulsions acting as vertex detector was complemented by electronic detectors for kinematic measurements and muon identification. Here we present first results on the analysis of nuclear emulsions exposed in the 2018 run, which prove the capability of reconstructing proton interaction vertices in a harsh environment, where the signal is largely dominated by secondary particles produced in hadronic and electromagnetic showers within the lead target.

2023-02-01, DIB VENTURELLI, CLAUDIO OMAR, Helo, Juan Carlos, Lyubovitskij, Valery E., Neill, Nicolás A., Soffer, Abner, Wang, Zeren Simon

Abstract We propose a search for B meson decays to a baryon plus missing energy at the Belle II experiment to probe supersymmetry with a GeV-scale lightest neutralino $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 and R-parity violation (RPV). We perform analytic computations of the signal branching fractions in the framework of effective field theory, with a single nonzero RPV operator $$ {\lambda}_{ij3}^{\prime \prime }{\overline{U}}_i^c{\overline{D}}_j^c{\overline{D}}_3^c $$ λ ij 3 ′ ′ U ¯ i c D ¯ j c D ¯ 3 c , where i, j = 1, 2. The hadronic form factors are calculated using an SU(3) phenomenological Lagrangian approach for the proton, as well as several hyperons and charmed baryons. Since the decay of the neutralino is kinematically and CKM suppressed in this theoretical scenario, it decays outside the detector and appears experimentally only as missing energy. We detail the analysis techniques at the experimental level and estimate the background in the $$ {B}^{+}\to p{\overset{\sim }{\chi}}_1^0 $$ B + → p χ ~ 1 0 search using published results for $$ {B}^{+}\to {K}^{+}\nu \overline{\nu} $$ B + → K + ν ν ¯ . Our final sensitivity plots are shown for both $$ {\lambda}_{113}^{\prime \prime } $$ λ 113 ′ ′ versus the squark mass $$ {m}_{\tilde{q}} $$ m q ~ and $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 versus the neutralino mass $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 . We find that the search at Belle II could probe $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 down to the order of 10−8 GeV−2 in the kinematically allowed $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 range. We also obtain current limits on $$ {\lambda}_{123}^{\prime \prime } $$ λ 123 ′ ′ by recasting an existing search interpreted as $$ {B}^0\to {\Lambda}^0{\overset{\sim }{\chi}}_1^0 $$ B 0 → Λ 0 χ ~ 1 0 , and comment about searches for $$ {B}^{+}\to {\Sigma}^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Σ + χ ~ 1 0 , $$ {B}^0\to {\Sigma}^0{\chi}_1^0 $$ B 0 → Σ 0 χ 1 0 , $$ {B}^{+}\to {\Lambda}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Λ c + χ ~ 1 0 , and $$ {B}^{+}\to {\Xi}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Ξ c + χ ~ 1 0 . In closing, we briefly discuss potential searches at the LHCb and BESIII experiments.

2015-01-01, CVETIC , GORAZD, DIB VENTURELLI, CLAUDIO OMAR, Kim, Choong Sun, Zamora-Saá, Jilberto

Some of the outstanding questions of particle physics today concern the neutrino sector, in particular whether there are more neutrinos than those already known and whether they are Dirac or Majorana particles. There are different ways to explore these issues. In this article we describe neutrino-mediated decays of charged pseudoscalar mesons such as π±,K± and B±, in scenarios where extra neutrinos are heavy and can be on their mass shell. We discuss semileptonic and leptonic decays of such kinds. We investigate possible ways of using these decays in order to distinguish between the Dirac and Majorana character of neutrinos. Further, we argue that there are significant possibilities of detecting CP violation in such decays when there are at least two almost degenerate Majorana neutrinos involved. This latter type of scenario fits well into the known neutrino minimal standard model (νMSM) which could simultaneously explain the Dark Matter and Baryon Asymmetry of the Universe.

2022-03-01, Ahdida, C., Akmete, A., Albanese, R., Alt, J., Alexandrov, A., Anokhina, A., Aoki, S., Arduini, G., Atkin, E., Azorskiy, N., Back, J. J., Bagulya, A., Baaltasar Dos Santos, F., Baranov, A., Bardou, F., Barker, G. J., Battistin, M., Bauche, J., Bay, A., Bayliss, V., Bencivenni, G., Berdnikov, A. Y., Berdnikov, Y. A., Bertani, M., Betancourt, C., Bezshyiko, I., Bezshyyko, O., Bick, D., Bieschke, S., Blanco, A., Boehm, J., Bogomilov, M., Boiarska, I., Bondarenko, K., Bonivento, W. M., Borburgh, J., Boyarsky, A., Brenner, R., Breton, D., Brignoli, A., Büscher, V., Buonaura, A., Buontempo, S., Cadeddu, S., Calcaterra, A., Calviani, M., Campanelli, M., Casolino, M., Charitonidis, N., Chau, P., Chauveau, J., Chepurnov, A., Chernyavskiy, M., Choi, K. Y., Chumakov, A., Ciambrone, P., Cicero, V., Climescu, M., Conaboy, A., Congedo, L., Cornelis, K., Cristinziani, M., Crupano, A., Dallavalle, G. M., Datwyler, A., D'Ambrosio, N., D'Appollonio, G., De Asmundis, R., De Carvalho Saraiva, J., De Lellis, G., De Magistris, M., De Roeck, A., De Serio, M., De Simone, D., Dedenko, L., Dergachev, P., Di Crescenzo, A., Di Giulio, L., Di Marco, N., Dib Venturelli, Claudio Omar, Dijkstra, H., Dmitrenko, V., Dougherty, L. A., Dolmatov, A., Domenici, D., Donskov, S., Drohan, V., Dubreuil, A., Durhan, O., Ehlert, M., Elikkaya, E., Enik, T., Etenko, A., Fabbri, F., Fedin, O., Fedotovs, F., Felici, G., V. Lyubovitskij, Kovalenko, Sergey, Hayk Hakobyan

Abstract In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goliath magnet at the H4 proton beam-line. Behind the magnet, scintillating-fibre, drift-tube and RPC detectors were placed. The purpose of this run was to validate the measurement's feasibility, to develop the required analysis tools and fine-tune the detector layout. In this paper, we present the track reconstruction in the pixel tracker and the track matching with the moving emulsion detector. The pixel detector performed as expected and it is shown that, after proper alignment, a vertex matching rate of 87% is achieved.

2018-02-01, DIB VENTURELLI, CLAUDIO OMAR, Kim, C. S., Neill, Nicolás A., Yuan, Xing Bo

We study the possibility to observe sterile neutrinos with masses in the range between 5 GeV and 20 GeV at the LHC, using the exclusive semileptonic modes involving pions, namely W to lepton + N to n pions + lepton+lepton (n = 1, 2, 3). The two pion and three pion modes require extrapolations of form factors to large time-like q2, which we do using vector dominance models as well as light front holographic QCD, with remarkable agreement. This mass region is difficult to explore with inclusive dilepton+dijet modes or trilepton modes and impossible to explore in rare meson decays. While particle identification is a real challenge in these modes, vertex displacement due to the long living neutrino in the above mass range can greatly help reduce backgrounds. Assuming a sample of 109 W bosons at the end of the LHC Run 2, these modes could discover a sterile neutrino in the above mass range or improve the current bounds on the heavy-to-light lepton mixings by an order of magnitude, U2lN∼2×10−6. Moreover, by studying the equal sign and opposite sign dileptons, the Majorana or Dirac character of the sterile neutrino may be revealed.

2020-02-01, DIB VENTURELLI, CLAUDIO OMAR, Kim, C. S., Araya, Sebastian Tapia

We study the feasibility to observe sterile neutrinos with masses in the range 5 GeV

2017-10-01, DIB VENTURELLI, CLAUDIO OMAR, Kim, C. S., Wang, Kechen

We present a search strategy for both Dirac and Majorana sterile neutrinos from the purely leptonic decays of W± → e± e± μ∓ ν and μ± μ± e∓ ν at the 14 TeV LHC. The discovery and exclusion limits for sterile neutrinos are shown using both the Cut-and-Count (CC) and Multi-Variate Analysis (MVA) methods. We also discriminate between Dirac and Majorana sterile neutrinos by exploiting a set of kinematic observables which differ between the Dirac and Majorana cases. We find that the MVA method, compared to the more common CC method, can greatly enhance the discovery and discrimination limits. Two benchmark points with sterile neutrino mass mN = 20 GeV and 50 GeV are tested. For an integrated luminosity of 3000 fb−1, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings |UNe|2 ∼ |UNμ|2∼ 10−6, while Majorana vs. Dirac discrimination can be reached if at least one of the mixings is of order 10−5.

2015-01-01, Dib Venturelli, Claudio Omar, Campos, Miguel, Kim, C. S.

We study the possibility of having CP asymmetries in the decay K± → π ∓` ±` ± (` = e, µ). This decay violates Lepton Number by two units and occurs only if there are Majorana particles that mediate the transition. Even though the absolute rate is highly suppressed by current bounds, we search for Majorana neutrino scenarios where the CP asymmetry arising from the lepton sector could be sizeable. This is indeed the case if there are two or more Majorana neutrinos with similar masses in the range around 102 MeV. In particular, the asymmetry is potentially near unity if two neutrinos are nearly degenerate, in the sense ∆mN ∼ ΓN . The full decay, however, may be difficult to detect not only because of the suppression caused by the heavy-to-light lepton mixing, but also because of the long lifetime of the heavy neutrino, which would induce large space separation between the two vertices where the charge leptons are produced. This particular problem should be less serious in heavier meson decays, as they involve heavier neutrinos with shorter lifetimes.