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Author (down) Nascimento, J.R.; Olmo, G.J.; Petrov, A.Y.; Porfirio, P.J. url  doi
openurl 
  Title On metric-affine bumblebee model coupled to scalar matter Type Journal Article
  Year 2024 Publication Nuclear Physics B Abbreviated Journal Nucl. Phys. B  
  Volume 1004 Issue Pages 116577 - 10pp  
  Keywords  
  Abstract We consider the coupling of the metric-affine bumblebee gravity model to scalar matter and calculate the lower -order contributions to two -point functions of bumblebee and scalar fields in the weak gravity approximation. We also obtain the one -loop effective potentials for both scalar and vector fields.  
  Address [Nascimento, J. R.; Petrov, A. Yu.; Porfirio, P. J.] Univ Fed Paraiba, Dept Fis, Caixa Postal 5008, BR-58051970 Joao Pessoa, PB, Brazil, Email: jroberto@fisica.ufpb.br;  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0550-3213 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001248177100001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6157  
Permanent link to this record
 
 
Author (down) Napiralla, P. et al; Domingo-Pardo, C. doi  openurl
  Title Benchmarking the PreSPEC@GSI experiment for Coulex-multipolarimetry on the pi(p3/2) -> pi(p1/2) spin-flip transition in 85Br Type Journal Article
  Year 2020 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A  
  Volume 56 Issue 5 Pages 147 - 10pp  
  Keywords  
  Abstract A first performance test of the Coulomb excitation multipolarimetry (Coulex-multipolarimetry) method is presented. It is based on a 85Br pp3/ 2. pp1/ 2 spinflip experiment performed as part of the PreSPEC-AGATA campaign at the GSI Helmholtzzentrum fur Schwerionen-forschung (GSI). Via determination of background levels around the expected 85Br excitations as well as measured 197Au excitations, an upper limit for the M1 transition strength of the 1/2- 1. 3/2- g.s. transition in 85Br and a lower beam time limit for upcoming experimental campaigns utilizing Coulex-multipolarimetry have been inferred. The impact of the use of AGATA in its anticipated 1p configuration on these estimates is deduced via Geant4 simulations.  
  Address [Napiralla, P.; Lettmann, M.; Stahl, C.; Pietralla, N.; Boutachkov, P.; Cortes, M. L.; John, P. R.; Lizarazo, C.; Louchart-Henning, C.; Merchan, E.; Moeller, O.; Moeller, T.; Ralet, D.; Werner, V] Tech Univ Darmstadt, Inst Kernphys, Schlossgartenstr 9, D-64289 Darmstadt, Germany, Email: pnapiralla@ikp.tu-darmstadt.de  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6001 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000541855500002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4441  
Permanent link to this record
 
 
Author (down) Nadal-Gisbert, S.; Navarro-Salas, J.; Pla, S. url  doi
openurl 
  Title Low-energy states and CPT invariance at the big bang Type Journal Article
  Year 2023 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 107 Issue 8 Pages 085018 - 16pp  
  Keywords  
  Abstract In this paper, we analyze the quantum vacuum in a radiation-dominated and CPT -invariant universe by further imposing the quantum states to be ultraviolet regular i.e., satisfying the Hadamard/adiabatic condition. For scalar fields, this is enforced by constructing the vacuum via the states of low-energy proposal. For spin -12 fields, we extend this proposal for a FLRW spacetime and apply it for the radiation-dominated and CPT -invariant universe. We focus on minimizing the smeared energy density around the big bang and give strong evidence that the resulting states satisfy the Hadamard/adiabatic condition. These states are then self -consistent candidates as effective big bang quantum vacuum from the field theory perspective.  
  Address [Nadal-Gisbert, Sergi; Navarro-Salas, Jose] Univ Valencia, Ctr Mixto Univ Valencia, CSIC Fac Fis, Dept Fis Teor, Valencia 46100, Spain, Email: sergi.nadal@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000981997800003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5585  
Permanent link to this record
 
 
Author (down) Nada, A.; Ramos, A. url  doi
openurl 
  Title An analysis of systematic effects in finite size scaling studies using the gradient flow Type Journal Article
  Year 2021 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C  
  Volume 81 Issue 1 Pages 1 - 19pp  
  Keywords  
  Abstract We propose a new strategy for the determination of the step scaling function sigma (u) in finite size scaling studies using the gradient flow. In this approach the determination of sigma (u) is broken in two pieces: a change of the flow time at fixed physical size, and a change of the size of the system at fixed flow time. Using both perturbative arguments and a set of simulations in the pure gauge theory we show that this approach leads to a better control over the continuum extrapolations. Following this new proposal we determine the running coupling at high energies in the pure gauge theory and re-examine the determination of the Lambda -parameter, with special care on the perturbative truncation uncertainties.  
  Address [Nada, Alessandro] DESY, John von Neumann Inst Comp NIC, Platanenallee 6, D-15738 Zeuthen, Germany, Email: alberto.ramos@cern.ch  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6044 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000606481000001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4678  
Permanent link to this record
 
 
Author (down) Nacher, E.; Briz, J.A.; Nerio, A.N.; Perea, A.; Tavora, V.G.; Tengblad, O.; Ciemala, M.; Cieplicka-Orynczak, N.; Maj, A.; Mazurek, K.; Olko, P.; Zieblinski, M.; Borge, M.J.G. url  doi
openurl 
  Title Characterization of a novel proton-CT scanner based on Silicon and LaBr3(Ce) detectors Type Journal Article
  Year 2024 Publication European Physical Journal Plus Abbreviated Journal Eur. Phys. J. Plus  
  Volume 139 Issue 5 Pages 404 - 9pp  
  Keywords  
  Abstract Treatment planning systems at proton-therapy centres entirely use X-ray computed tomography (CT) as primary imaging technique to infer the proton treatment doses to tumour and healthy tissues. However, proton stopping powers in the body, as derived from X-ray images, suffer from important proton-range uncertainties. In order to reduce this uncertainty in range, one could use proton-CT images instead. The main goal of this work is to test the capabilities of a newly-developed proton-CT scanner, based on the use of a set of tracking detectors and a high energy resolution scintillator for the residual energy of the protons. Different custom-made phantoms were positioned at the field of view of the scanner and were irradiated with protons at the CCB proton-therapy center in Krakow. We measured with the phantoms at different angles and produced sinograms that were used to obtain reconstructed images by Filtered Back-Projection. The obtained images were used to determine the capabilities of our scanner in terms of spatial resolution and proton Relative Stopping Power (RSP) mapping and validate its use as proton-CT scanner. The results show that the scanner can produce medium-high quality images, with spatial resolution better than 2 mm in radiography, below 3 mm in tomography and resolving power in the RSP comparable to other state-of-the-art pCT scanners.  
  Address [Nacher, E.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia 46980, Spain, Email: enrique.nacher@csic.es  
  Corporate Author Thesis  
  Publisher Springer Heidelberg Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2190-5444 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001218502700005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6123  
Permanent link to this record
 
 
Author (down) NA64 Collaboration (Cazzaniga, C. et al); Molina Bueno, L. url  doi
openurl 
  Title Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel Type Journal Article
  Year 2021 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C  
  Volume 81 Issue 10 Pages 959 - 6pp  
  Keywords  
  Abstract We report the results of a search for a new vector boson (A') decaying into two dark matter particles chi 1 chi 2 of different mass. The heavier chi(2) particle subsequently decays to chi 1 and an off-shell Dark Photon A'* -> e(+)e(-). For a sufficiently largemass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in themuon anomalous magnetic moment at Fermilab. Remark- ably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained reanalyzing the previous NA64 searches for an invisible decay A' -> chi(chi) over bar and axion-like or pseudo-scalar particles -> gamma gamma. With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for A' masses from 2m(e) up to 390 MeV and mixing parameter e between 3 x 10(-5) and 2 x 10(-2).  
  Address [Cazzaniga, C.; Odagiu, P.; Depero, E.; Bueno, L. Molina; Crivelli, P.; Radics, B.; Rubbia, A.; Sieber, H.] Swiss Fed Inst Technol, Inst Particle Phys & Astrophys, CH-8093 Zurich, Switzerland, Email: Paolo.Crivelli@cern.ch  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6044 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000712961200001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5013  
Permanent link to this record
 
 
Author (down) NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L.; Tuzi, M. url  doi
openurl 
  Title Search for Light Dark Matter with NA64 at CERN Type Journal Article
  Year 2023 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 131 Issue 16 Pages 161801 - 7pp  
  Keywords  
  Abstract Thermal dark matter models with particle chi masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV chi production through the interaction mediated by a new vector boson, called the dark photon A ' , in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS. With 9.37 x 10(11) electrons on target collected during 2016-2022 runs NA64 probes for the first time the well-motivated region of parameter space of benchmark thermal scalar and fermionic dark matter models. No evidence for dark matter production has been found. This allows us to set the most sensitive limits on the A ' couplings to photons for masses m(A ') less than or similar to 0.35 GeV, and to exclude scalar and Majorana dark matter with the chi – A ' coupling alpha(D) <= 0.1 for masses 0.001 less than or similar to m(chi) less than or similar to 0.1 GeV and 3m(chi) <= m(A ').  
  Address [Andreev, Yu. M.; Chumakov, A. G.; Dermenev, A. V.; Donskov, S. V.; Dusaev, R. R.; Enik, T.; Frolov, V. N.; Gertsenberger, S. V.; Gninenko, S. N.; Kachanov, V. A.; Karneyeu, A. E.; Kasianova, E. A.; Kekelidze, G. D.; Kramarenko, V. A.; Kravchuk, L. V.; Krasnikov, N. V.; Lyubovitskij, V. E.; Lysan, V.; Matveev, V. A.; Peshekhonov, D., V; Polyakov, V. A.; Salamatin, K. M.; Samoylenko, V. D.; Shchukin, D. A.; Tikhomirov, V. O.; Tlisova, I.; Toropin, A. N.; Vasilishin, B. I.; Volkov, P. V.; Volkov, V. Yu.; Voronchikhin, I. V.; Zhevlakov, A. S.] CERN, Geneva, Switzerland, Email: sergei.gninenko@cern.ch  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001098606400001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5805  
Permanent link to this record
 
 
Author (down) NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L.; Tuzi, M. url  doi
openurl 
  Title Probing light dark matter with positron beams at NA64 Type Journal Article
  Year 2024 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 109 Issue 3 Pages L031103 - 6pp  
  Keywords  
  Abstract We present the results of a missing-energy search for light dark matter which has a new interaction with ordinary matter transmitted by a vector boson, called dark photon A'. For the first time, this search is performed with a positron beam by using the significantly enhanced production of A' in the resonant annihilation of positrons with atomic electrons of the target nuclei, followed by the invisible decay of A' into dark matter. No events were found in the signal region with (10.1 +/- 0.1) x 109 positrons on target with 100 GeV energy. This allowed us to set new exclusion limits that, relative to the collected statistics, prove the power of this experimental technique. This measurement is a crucial first step toward a future exploration program with positron beams, whose estimated sensitivity is here presented.  
  Address [Andreev, Yu. M.; Dermenev, A. V.; Donskov, S. V.; Dusaev, R. R.; Enik, T.; Frolov, V. N.; Kachanov, V. A.; Karneyeu, A. E.; Kirpichnikov, D. V.; Kirsanov, M. M.; Kolosov, V. N.; Gertsenberger, S. V.; Kasianova, E. A.; Kramarenko, V. A.; Kravchuk, L. V.; Krasnikov, N. V.; Lysan, V.; Matveev, V. A.; Samoylenko, V. D.; Shchukin, D.; Tikhomirov, V. O.; Tlisova, I.; Toropin, A. N.; Volkov, P. V.; Volkov, V. Yu.; Voronchikhin, I. V.; Zhevlakov, A. S.] CERN, Meyrin, Switzerland, Email: pietro.bisio@ge.infn.it  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001180160500008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6009  
Permanent link to this record
 
 
Author (down) NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L.; Tuzi, M. url  doi
openurl 
  Title First Results in the Search for Dark Sectors at NA64 with the CERN SPS High Energy Muon Beam Type Journal Article
  Year 2024 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 132 Issue 21 Pages 211803 - 7pp  
  Keywords  
  Abstract We report the first search for dark sectors performed at the NA64 experiment employing a high energy muon beam and a missing energy-momentum technique. Muons from the M2 beamline at the CERN Super Proton Synchrotron with a momentum of 160 GeV/c are directed to an active target. The signal signature consists of a single scattered muon with momentum < 80 GeV/c in the final state, accompanied by missing energy, i.e., no detectable activity in the downstream calorimeters. For a total dataset of (1.98 +/- 0.02) x 10(10) muons on target, no event is observed in the expected signal region. This allows us to set new limits on the remaining (m(Z)'; g(Z)') parameter space of a new Z' (L-mu – L-tau) vector boson which could explain the muon (g – 2)(mu) anomaly. Additionally, our study excludes part of the parameter space suggested by the thermal dark matter relic abundance. Our results pave the way to explore dark sectors and light dark matter with muon beams in a unique and complementary way to other experiments.  
  Address [Banerjee, D.; Bernhard, J.; Charitonidis, N.; Girod, S.] CERN, European Org Nucl Res, CH-1211 Geneva, Switzerland, Email: paolo.crivelli@cern.ch;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001239696000003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6142  
Permanent link to this record
 
 
Author (down) NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L. url  doi
openurl 
  Title Search for pseudoscalar bosons decaying into e(+)e(-) pairs in the NA64 experiment at the CERN SPS Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 104 Issue 11 Pages L111102 - 5pp  
  Keywords  
  Abstract We report the results of a search for a light pseudoscalar particle a that couples to electrons and decays to e(+) e(-) perfbnned using the high-energy CERN SPS H4 electron beam. If such light pseudoscalar exists, it could explain the ATOMKI anomaly (an excess of e(+) e(-) pairs in the nuclear transitions of Be-8 and 4 He nuclei at the invariant mass similar or equal to 17 MeV observed by the experiment at the 5 MV Van de Graaff accelerator at ATOMKI, Hungary). We used the NA64 data collected in the “visible mode” configuration with a total statistics corresponding to 8.4 x 10(10) electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter epsilon we also used the data collected in 2016-2018 in the “invisible mode” configuration of NA64 with a total statistics corresponding to 2.84 x 10(11) EOT. The background and efficiency estimates for these two configurations were retained from our previous analyses searching for light vector bosons and axionlike particles (ALP) (the latter were assumed to couple predominantly to gamma). In this work we recalculate the signal yields, which are different due to different cross section and lifetime of a pseudoscalar particle a, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space m(a) – epsilon in the mass range from 1 to 17.1 MeV is excluded. At the mass of the central value of the ATOMKI anomaly (the first result obtained on the beryllium nucleus, 16.7 MeV) the values of epsilon in the range 2.1 x 10(-4) < epsilon < 3.2 x 10(-4) are excluded.  
  Address [Hoesgen, M.; Ketzer, B.] Univ Bonn, Helmholtz Inst Strahlen & Kernphys, D-53115 Bonn, Germany  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000738796900005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5071  
Permanent link to this record
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