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Author |
Wuensch, W.; Degiovanni, A.; Calatroni, S.; Korsback, A.; Djurabekova, F.; Rajamaki, R.; Giner-Navarro, J. |
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Title |
Statistics of vacuum breakdown in the high-gradient and low-rate regime |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review Accelerators and Beams |
Abbreviated Journal |
Phys. Rev. Accel. Beams |
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Volume |
20 |
Issue |
1 |
Pages |
011007 - 11pp |
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Abstract |
In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DCto 12GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments. |
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Address |
[Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio] CERN, European Org Nucl Res, CH-1211 Geneva, Switzerland, Email: anders.korsback@helsinki.fi |
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Amer Physical Soc |
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English |
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ISSN |
2469-9888 |
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Conference |
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Notes |
WOS:000400781300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3125 |
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Author |
del Rio, A.; Ferreiro, A.; Navarro-Salas, J.; Torrenti, F. |
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Title |
Adiabatic regularization with a Yukawa interaction |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
95 |
Issue |
10 |
Pages |
105003 - 19pp |
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Keywords |
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Abstract |
We extend the adiabatic regularization method for an expanding universe to include the Yukawa interaction between quantized Dirac fermions and a homogeneous background scalar field. We give explicit expressions for the renormalized expectation values of the stress-energy tensor < T-mu nu > and the bilinear <(psi) over bar psi > in a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. These are basic ingredients in the semiclassical field equations of fermionic matter in curved spacetime interacting with a background scalar field. The ultraviolet subtracting terms of the adiabatic regularization can be naturally interpreted as coming from appropriate counterterms of the background fields. We fix the required covariant counterterms. To test our approach we determine the contribution of the Yukawa interaction to the conformal anomaly in the massless limit and show its consistency with the heat-kernel method using the effective action. |
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Address |
[del Rio, Adrian; Ferreiro, Antonio; Navarro-Salas, Jose] Univ Valencia, Fac Fis, Ctr Mixto Univ Valencia CSIC, Dept Fis Teor, E-46100 Valencia, Spain, Email: adrian.rio@uv.es; |
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Amer Physical Soc |
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English |
Summary Language |
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Original 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 |
2470-0010 |
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Conference |
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Notes |
WOS:000401447900006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
3127 |
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LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Valls, P.; Sanchez Mayordomo, C. |
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Title |
Measurement of the B-s(0)-> mu(+) mu(-) Branching Fraction and Effective Lifetime and Search for B-0 ->mu(+) mu(-) Decays |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
118 |
Issue |
19 |
Pages |
191801 - 11pp |
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Keywords |
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Abstract |
A search for the rare decays B-s(0)->mu(+)mu(-) and B-0 -> mu(+)mu(-) is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb(-1). An excess of B-s(0) -> mu(+)mu- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B-s(0) -> mu(+)mu(-)) = (3.0 +/- 0.6(-0.2)(+)(0.3)) x 10(-9), where the first uncertainty is statistical and the second systematic. The first measurement of the B-s(0) -> mu(+)mu(-) effective lifetime, tau(B-s(0)-> mu(+) mu(-)) = 2.04 +/- 0.44 +/- 0.05 ps, is reported. No significant excess of B-0 -> mu(+)mu(-) decays is found, and a 95% confidence level upper limit, B(B-0 -> mu(+)mu(-) ) < 3.4 x 10(-10), is determined. All results are in agreement with the standard model expectations. |
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Address |
[Bediaga, I.; De Miranda, J. M.; Gomes, A.; Massafferri, A.; Molina Rodriguez, J.; Dos Reis, A. C.; Rodrigues, A. B.; Salustino Guimaraes, V.; Soares Lavra, I.; Tourinho Jadallah Aoude, R.] CBPF, Rio De Janeiro, Brazil |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
0031-9007 |
ISBN |
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Conference |
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Notes |
WOS:000401240300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3128 |
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Author |
T2K Collaboration (Abe, K. et al); Cervera-Villanueva, A.; Izmaylov, A.; Novella, P.; Sorel, M.; Stamoulis, P. |
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Title |
First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
95 |
Issue |
1 |
Pages |
012010 - 11pp |
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Keywords |
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Abstract |
The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies similar to 0.8 GeV. The differential measurements are presented as a function of the muon and pion kinematics, in the restricted phase space defined by p(pi+) > 200 MeV/c, p(mu) > 200 MeV/c, cos(theta(pi+)) > 0.3 and cos(theta(mu)) > 0.3. The total flux integrated nu(mu) charged current single positive pion production cross section on water in the restricted phase space is measured to be <sigma >(phi) = 4.25 +/- 0.48(stat) +/- 1.56(syst) x 10(-40) cm(2)/nucleon. The total cross section is consistent with the NEUT prediction (5.03 x 10(-40) cm(2)/nucleon) and 2 sigma lower than the GENIE prediction (7.68 x 10(-40) cm(2)/nucleon). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but overestimates the overall cross section normalization. |
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Address |
[Ariga, A.; Ereditato, A.; Hierholzer, M.; Nirkko, M.; Pistillo, C.; Redij, A.; Wilkinson, C.] Univ Bern, Albert Einstein Ctr Fundamental Phys, High Energy Phys Lab, Bern, Switzerland |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
2470-0010 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000400774700003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3135 |
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Author |
Kim, C.S.; Lopez-Castro, G.; Tostado, S.L.; Vicente, A. |
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Title |
Remarks on the Standard Model predictions for R(D) and R(D*) |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
95 |
Issue |
1 |
Pages |
013003 - 7pp |
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Keywords |
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Abstract |
Semileptonic b -> c transitions, and in particular the ratios R(D-(*())) = Gamma(B -> D-(*())tau nu)/Gamma(B -> D-(*())l nu), can be used to test the universality of the weak interactions. In light of the recent discrepancies between the experimental measurements of these observables by the BABAR, Belle, and LHCb collaborations and the Standard Model predicted values, we study the robustness of the latter. Our analysis reveals that R(D) might be enhanced by lepton mass effects associated to the mostly unknown scalar form factor. In contrast, the Standard Model prediction for R(D*) is found to be more robust, because possible pollutions from B* contributions turn out to be negligibly small; this indicates that R(D) is a promising observable for searches of new physics. |
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Address |
[Kim, C. S.] Yonsei Univ, Dept Phys, Seoul 120749, South Korea, Email: cskim@yonsei.ac.kr; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
2470-0010 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000400774700004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3136 |
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