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Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Valls, P.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
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Title |
Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at root s=7 TeV |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages  |
025 - 22pp |
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Keywords |
Hadron-Hadron scattering (experiments); Particle correlations and fluctuations; QCD |
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Abstract |
Bose-Einstein correlations of same-sign charged pions, produced in proton-proton collisions at a 7TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decrease. |
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Address |
[Bediagal, I.; Torres, M. Cruz; De Mirandal, J. M.; Gomes, A.; Maev, O.; Massafferri, A.; Rodriguezl, J. Molina; dos Reis, A. C.; Rodrigues, A. B.; Guimaraes, V. Salustino; Schneider, O.; Lavra, O. Soares; Aoude, R. Tourinho Jadallah] CBPF, Rio De Janeiro, Brazil, Email: Marcin.Kucharczyk@cern.ch |
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Springer |
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English |
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1029-8479 |
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Notes |
WOS:000417757900003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3428 |
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Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Valls, P.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
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Title |
Measurement of the B-+/- production cross-section in pp collisions at root s=7 and 13 TeV |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
026 - 25pp |
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Keywords |
B physics; Hadron-Hadron scattering (experiments); Particle and resonance production |
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Abstract |
The production of B +/- mesons is studied in pp collisions at centre-of-mass energies of 7 and 13 TeV, using B-+/- -> J/psi K-+/- decays and data samples corresponding to 1.0 fb(-1) and 0.3 fb(-1), respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range 0 < pT < 40 GeV/c and the rapidity range 2.0 < y < 4.5 are measured to be sigma-(pp -> B-+/- X, root s = 7 TeV) = 43.0 +/- 0.2 +/- 2.5 +/- 1.7 μb, sigma(pp -> B-+/- X, root s = 13 TeV) = 86.6 +/- 0.5 +/- 5.4 +/- 3.4 μb, where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the B-+/- -> J/psi K-+/- branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be 2.02 +/- 0.02 (stat) +/- 0.12 (syst). Differential cross-sections are also reported as functions of pi, and y. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics. |
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Address |
[Bediaga, I.; Torres, M. Cruz; De Miranda, J. M.; Gomes, A.; Massafferril, A.; Rodriguez, J. Molina; Dos Reis, A. C.; Rodrigues, A. B.; Lavral, O. Soares; Aoudel, R. Tourinho Jadallah; Ukleja, A.] CBPF, Rio De Janeiro, Brazil, Email: hang.yin@cern.ch |
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Springer |
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English |
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ISSN |
1029-8479 |
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Conference |
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Notes |
WOS:000417757900004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3427 |
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Author |
Lopez-Honorez, L.; Mena, O.; Palomares-Ruiz, S.; Villanueva-Domingo, P.; Witte, S.J. |
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Title |
Variations in fundamental constants at the cosmic dawn |
Type |
Journal Article |
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Year |
2020 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
026 - 25pp |
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Keywords |
cosmology of theories beyond the SM; particle physics – cosmology connection; reionization |
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Abstract |
The observation of space-time variations in fundamental constants would provide strong evidence for the existence of new light degrees of freedom in the theory of Nature. Robustly constraining such scenarios requires exploiting observations that span different scales and probe the state of the Universe at different epochs. In the context of cosmology, both the cosmic microwave background and the Lyman-a forest have proven to be powerful tools capable of constraining variations in electromagnetism, however at the moment there do not exist cosmological probes capable of bridging the gap between recombination and reionization. In the near future, radio telescopes will attempt to measure the 21 cm transition of neutral hydrogen during the epochs of reionization and the cosmic dawn (and potentially the tail end of the dark ages); being inherently sensitive to electromagnetic phenomena, these experiments will offer a unique perspective on space-time variations of the fine-structure constant and the electron mass. We show here that large variations in these fundamental constants would produce features on the 21 cm power spectrum that may be distinguishable from astrophysical uncertainties. Furthermore, we forecast the sensitivity for the Square Kilometer Array, and show that the 21 cm power spectrum may be able to constrain variations at the level of O(10(-3)). |
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Address |
[Lopez-Honorez, Laura] Univ Libre Bruxelles, Serv Phys Theor, CP225, B-1050 Brussels, Belgium, Email: llopezho@ulb.ac.be; |
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Iop Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Notes |
WOS:000551875400049 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4473 |
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Author |
LHCb Collaboration (Aaij, R. et al); Jashal, B.K.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Vidal, J. |
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Title |
Precision measurement of forward Z boson production in proton-proton collisions at root s=13 TeV |
Type |
Journal Article |
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Year |
2022 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
026 - 57pp |
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Keywords |
Electroweak Interaction; Forward Physics; Hadron-Hadron Scattering; Particle and Resonance Production |
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Abstract |
A precision measurement of the Z boson production cross-section at root s = 13 TeV in the forward region is presented, using pp collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb(-1). The production cross-section is measured using Z -> mu(+)mu(-) events within the fiducial region defined as pseudorapidity 2.0 < eta < 4.5 and transverse momentum p(T) > 20 GeV/c for both muons and dimuon invariant mass 60 < M-mu μ< 120 GeV/c(2). The integrated cross-section is determined to be sigma(Z -> mu(+)mu(-)) = 196.4 +/- 0.2 +/- 1.6 +/- 3.9 pb, where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions within uncertainties. |
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Address |
[de Souza Leite, J. Baptista; Bediaga, I; Torres, M. Cruz; De Miranda, J. M.; dos Reis, A. C.; Falcao, L. N.; Gomes, A.; Massafferri, A.; Machado, D. Torres] Ctr Brasileiro Pesquisas Fis CBPF, Rio De Janeiro, Brazil, Email: hang.yin@cern.ch |
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Springer |
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English |
Summary Language |
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Abbreviated Series Title |
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ISSN |
1029-8479 |
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Notes |
WOS:000825333400003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5299 |
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Author |
NEXT Collaboration (Henriques, C.A.O. et al); Alvarez, V.; Benlloch-Rodriguez, J.M.; Botas, A.; Carcel, S.; Carrion, J.V.; Diaz, J.; Felkai, R.; Kekic, M.; Laing, A.; Lopez-March, N.; Martinez, A.; Martinez-Lema, G.; Muñoz Vidal, J.; Musti, M.; Nebot-Guinot, M.; Novella, P.; Palmeiro, B.; Perez, J.; Querol, M.; Renner, J.; Rodriguez, J.; Romo-Luque, C.; Simon, A.; Sorel, M.; Yahlali, N. |
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Title |
Electroluminescence TPCs at the thermal diffusion limit |
Type |
Journal Article |
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Year |
2019 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
01 |
Issue |
1 |
Pages |
027 - 23pp |
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Keywords |
Dark Matter and Double Beta Decay (experiments); Photon production; Particle correlations and fluctuations; Rare decay |
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Abstract |
The NEXT experiment aims at searching for the hypothetical neutrinoless double-beta decay from the Xe-136 isotope using a high-purity xenon TPC. Efficient discrimination of the events through pattern recognition of the topology of primary ionisation tracks is a major requirement for the experiment. However, it is limited by the diffusion of electrons. It is known that the addition of a small fraction of a molecular gas to xenon reduces electron diffusion. On the other hand, the electroluminescence (EL) yield drops and the achievable energy resolution may be compromised. We have studied the effect of adding several molecular gases to xenon (CO2, CH4 and CF4) on the EL yield and energy resolution obtained in a small prototype of driftless gas proportional scintillation counter. We have compared our results on the scintillation characteristics (EL yield and energy resolution) with a microscopic simulation, obtaining the diffusion coefficients in those conditions as well. Accordingly, electron diffusion may be reduced from about 10 for pure xenon down to 2.5 using additive concentrations of about 0.05%, 0.2% and 0.02% for CO2, CH4 and CF4, respectively. Our results show that CF4 admixtures present the highest EL yield in those conditions, but very poor energy resolution as a result of huge fluctuations observed in the EL formation. CH4 presents the best energy resolution despite the EL yield being the lowest. The results obtained with xenon admixtures are extrapolated to the operational conditions of the NEXT-100 TPC. CO2 and CH4 show potential as molecular additives in a large xenon TPC. While CO2 has some operational constraints, making it difficult to be used in a large TPC, CH4 shows the best performance and stability as molecular additive to be used in the NEXT-100 TPC, with an extrapolated energy resolution of 0.4% at 2.45 MeV for concentrations below 0.4%, which is only slightly worse than the one obtained for pure xenon. We demonstrate the possibility to have an electroluminescence TPC operating very close to the thermal diffusion limit without jeopardizing the TPC performance, if CO2 or CH4 are chosen as additives. |
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Address |
[Henriques, C. A. O.; Monteiro, C. M. B.; Freitas, E. D. C.; Mano, R. D. P.; Jorge, M. R.; Fernandes, A. F. M.; Fernandes, L. M. P.; dos Santos, J. M. F.] Univ Coimbra, Phys Dept, LIBPhys, Rua Larga, P-3004516 Coimbra, Portugal, Email: pancho@gian.fis.uc.pt |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1029-8479 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000455157300002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3873 |
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| Permanent link to this record |
