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Author Anderson, P.R.; Clark, R.D.; Fabbri, A.; Good, M.R.R. url  doi
openurl 
  Title Late time approach to Hawking radiation: Terms beyond leading order Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 100 Issue 6 Pages 061703 - 5pp  
  Keywords  
  Abstract Black hole evaporation is studied using wave packets for the modes. These allow for approximate frequency and time resolution. The leading order late time behavior gives the well-known Hawking radiation that is independent of how the black hole formed. The focus here is on the higher order terms and the rate at which they damp at late times. Some of these terms carry information about how the black hole formed. A general argument is given which shows that the damping is significantly slower (power law) than what might be naively expected from a stationary phase approximation (exponential). This result is verified by numerical calculations in the cases of 2D and 4D black holes that form from the collapse of a null shell.  
  Address (up) [Anderson, Paul R.; Clark, Raymond D.] Wake Forest Univ, Dept Phys, Winston Salem, NC 27109 USA, Email: anderson@wfu.edu;  
  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:000487736400001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4151  
Permanent link to this record
 

 
Author Anderson, P.R.; Siahmazgi, S.G.; Clark, R.D.; Fabbri, A. url  doi
openurl 
  Title Method to compute the stress-energy tensor for a quantized scalar field when a black hole forms from the collapse of a null shell Type Journal Article
  Year 2020 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 102 Issue 12 Pages 125035 - 26pp  
  Keywords  
  Abstract A method is given to compute the stress-energy tensor for a massless minimally coupled scalar field in a spacetime where a black hole forms from the collapse of a spherically symmetric null shell in four dimensions. Part of the method involves matching the modes for the in vacuum state to a complete set of modes in Schwarzschild spacetime. The other part involves subtracting from the unrenormalized expression for the stress-energy tensor when the field is in the in vacuum state, the corresponding expression when the field is in the Unruh state and adding to this the renormalized stress-energy tensor for the field in the Unruh state. The method is shown to work in the two-dimensional case where the results are known.  
  Address (up) [Anderson, Paul R.; Siahmazgi, Shohreh Gholizadeh; Clark, Raymond D.] Wake Forest Univ, Dept Phys, Winston Salem, NC 27109 USA, Email: anderson@wfu.edu;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language Spanish 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:000604246500005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4673  
Permanent link to this record
 

 
Author NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L. url  doi
openurl 
  Title Improved exclusion limit for light dark matter from e(+) e(-) annihilation in NA64 Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 104 Issue 9 Pages L091701 - 7pp  
  Keywords  
  Abstract The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson A' were set by the NA64 experiment for the mass region m(A') less than or similar to 250 MeV, by analyzing data from the interaction of 2.84 x 10(11) 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by including A' production via secondary positron annihilation with atomic electrons, we extend these limits in the 200-300 MeV region by almost an order of magnitude, touching for the first time the dark matter relic density constrained parameter combinations. Our new results demonstrate the power of the resonant annihilation process in missing energy dark-matter searches, paving the road to future dedicated e(+) beam efforts.  
  Address (up) [Andreev, Yu M.; Dermenev, A., V; Gninenko, S. N.; Karneyeu, A. E.; Kirpichnikov, D., V; Kirsanov, M. M.; Kravchuk, L., V; Krasnikov, N., V; Tlisova, I; Toropin, A. N.] Inst Nucl Res, Moscow 117312, Russia, Email: andrea.celentano@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:000744291500008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5090  
Permanent link to this record
 

 
Author NA64 Collaboration (Andreev, Y.M. et al); Molina Bueno, L. url  doi
openurl 
  Title Search for a light Z' in the L-mu – L-tau scenario with the NA64-e experiment at CERN Type Journal Article
  Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 106 Issue 3 Pages 032015 - 12pp  
  Keywords  
  Abstract The extension of Standard Model made by inclusion of additional U(1) gauge L-mu – L-tau symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in B meson decays. This model predicts the existence of a new, light Z' vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. In this work, we present a rigorous evaluation of the upper limits in the Z' parameter space, obtained from the analysis of the data collected by the NA64-e experiment at CERN SPS, that performed a search for light dark matter with 2.84 x 10(11) electrons impinging with 100 GeV on an active thick target. The resulting limits touch the muon g – 2 preferred band for values of the Z' mass of order of 1 MeV, while the sensitivity projections for the future high-statistics NA64-e runs demonstrate the power of the electrons/positron beam approach in this theoretical scenario.  
  Address (up) [Andreev, Yu M.; Dermenev, A., V; Gninenko, S. N.; Karneyeu, A. E.; Kirpichnikov, D., V; Kirsanov, M. M.; Kravchuk, L., V; Krasnikov, N., V; Tlisova, I; Toropin, A. N.] Inst Nucl Res, Moscow 117312, Russia, Email: luca.marsicano@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:000862798400003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5376  
Permanent link to this record
 

 
Author Andreev, Y.M. et al; Molina Bueno, L.; Tuzi, M. url  doi
openurl 
  Title Measurement of the intrinsic hadronic contamination in the NA64-e high-purity e+/e- beam at CERN Type Journal Article
  Year 2023 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 1057 Issue Pages 168776 - 8pp  
  Keywords Light dark matter; Missing-energy experiment; H4 beamline; Hadron contamination  
  Abstract We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, antiprotons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.  
  Address (up) [Andreev, Yu. M.; Chumakov, A. G.; Dermenev, A. V.; Donskov, S. V.; Dusaev, R. R.; Enik, T.; Frolov, V. N.; Gerassimov, S. G.; Gninenko, S. N.; Kachanov, V. A.; Kambar, Y.; Karneyeu, A. E.; Kirsanov, M. M.; Kolosov, V. N.; Gertsenberger, S. V.; Kasianova, E. A.; Kramarenko, V. A.; Kravchuk, L. V.; Krasnikov, N. V.; Lyubovitskij, V. E.; Lysan, V.; Matveev, V. A.; Mikhailov, Yu. V.; Bueno, L. Molina; Peshekhonov, D. V.; Polyakov, V. A.; Salamatin, K.; Samoylenko, V. D.; Shchukin, D.; Tikhomirov, V. O.; Tlisova, I.; Toropin, A. N.; Trifonov, A. Yu.; Vasilishin, B. I.; Volkov, P. V.; Volkov, V. Yu.; Voronchikhin, I. V.; Zhevlakov, A. S.] CERN, Geneva, Switzerland, Email: pietro.bisio@ge.infn.it  
  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 0168-9002 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001154863600001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5923  
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