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Author |
Kleiss, R.H.P.; Malamos, I.; Papadopoulos, C.G.; Verheyen, R. |
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Title |
Counting to one: reducibility of one- and two-loop amplitudes at the integrand level |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
038 - 24pp |
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Keywords |
QCD Phenomenology; NLO Computations |
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Abstract |
Calculation of amplitudes in perturbative quantum field theory involve large loop integrals. The complexity of those integrals, in combination with the large number of Feynman diagrams, make the calculations very difficult. Reduction methods proved to be very helpful, lowering the number of integrals that need to be actually calculated. Especially reduction at the integrand level improves the speed and set-up of these calculations. In this article we demonstrate, by counting the numbers of tensor structures and independent coefficients, how to write such relations at the integrand level for one-and two-loop amplitudes. We clarify their connection to the so-called spurious terms at one loop and discuss their structure in the two-loop case. This method is also applicable to higher loops, and the results obtained apply to both planar and non-planar diagrams. |
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Address |
[Kleiss, Ronald H. P.; Verheyen, Rob] Radboud Univ Nijmegen, NL-6525 ED Nijmegen, Netherlands, Email: R.Kleiss@science.ru.nl; |
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Springer |
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English |
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ISSN |
1126-6708 |
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Notes  |
WOS:000313123800038 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1346 |
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Author |
Botella, F.J.; Branco, G.C.; Nebot, M. |
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Title |
The hunt for New Physics in the Flavour Sector with up vector-like quarks |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
040 - 34pp |
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Keywords |
Beyond Standard Model; Rare Decays; CP violation |
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Abstract |
We analyse the possible presence of New Physics (NP) in the Flavour Sector and evaluate its potential for solving the tension between the experimental values of A(J/Psi KS) and Br(B+ -> tau(+)v(tau)) with respect to the Standard Model (SM) expectations. Updated model independent analyses, where NP contributions are allowed in B-d(0) – (B) over bar (0)(d) and B-s(0) – (B) over bar (0)(s) transitions, suggest the need of New Physics in the bd sector. A detailed analysis of recent Flavour data is then presented in the framework of a simple extension of the SM, where a Q = 2/3 vector-like isosinglet quark is added to the spectrum of the SM. Special emphasis is given to the implications of this model for correlations among various measurable quantities. We include constraints from all the relevant quark flavour sectors and give precise predictions for selected rare processes. We find important deviations from the SM in observables in the bd sector like the semileptonic asymmetry A(SL)(d), B-d(0) -> mu(+)mu(-) and A(SL)(s) – A(SL)(d). Other potential places where NP can show up include A(J/Psi Phi), gamma, K-L(0) -> pi(0)v (v) over bar, t -> Zq and D-0 -> mu(+)mu(-) among others. The experimental data favours in this model the existence of an up vector-like quark with a mass below 600(1000) GeV at 1(2) sigma. |
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[Botella, F. J.; Nebot, M.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es; |
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Springer |
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English |
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1126-6708 |
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Notes |
WOS:000313123800040 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1344 |
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Author |
ATLAS Collaboration (Aad, G. et al); Cabrera Urban, S.; Castillo Gimenez, V.; Costa, M.J.; Fassi, F.; Ferrer, A.; Fiorini, L.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Hernandez Jimenez, Y.; Higon-Rodriguez, E.; Irles Quiles, A.; Kaci, M.; Lacasta, C.; Lacuesta, V.R.; Marti-Garcia, S.; Miñano, M.; Mitsou, V.A.; Moles-Valls, R.; Moreno Llacer, M.; Oliver Garcia, E.; Pedraza Lopez, S.; Perez Garcia-Estañ, M.T.; Romero Adam, E.; Ros, E.; Salt, J.; Sanchez Martinez, V.; Solans, C.A.; Soldevila, U.; Sanchez, J.; Torro Pastor, E.; Valero, A.; Valladolid Gallego, E.; Valls Ferrer, J.A.; Villaplana Perez, M.; Vos, M. |
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Title |
Time-dependent angular analysis of the decay B-s(0) -> J/psi phi and extraction of Delta Gamma(s) and the CP-violating weak phase phi(s) by ATLAS |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
072 - 34pp |
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Keywords |
Hadron-Hadron Scattering |
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Abstract |
A measurement of B-s(0) -> J/psi phi decay parameters, including the CP-violating weak phase phi(s) and the decay width difference Delta Gamma(s) is reported, using 4.9 fb(-1) of integrated luminosity collected in 2011 by the ATLAS detector from LHC pp collisions at a centre-of-mass energy root s = 7 TeV. The mean decay width Gamma(s) and the transversity amplitudes vertical bar A(0)(0)vertical bar(2) and vertical bar A(parallel to)(0)vertical bar(2) are also measured. The values reported for these parameters are: phi(s) = 0.22 +/- 0.41 (stat.) +/- 0.10 (syst.) rad Delta Gamma(s) = 0.053 +/- 0.021 (stat.) +/- 0.010 (syst.) ps(-1) Gamma(s) = 0.677 +/- 0.007 (stat.) +/- 0.004 (syst.) ps(-1) vertical bar A(0)(0)vertical bar(2) = 0.528 +/- 0.006 (stat.) +/- 0.009 (syst.) vertical bar A(parallel to)(0)vertical bar(2) = 0.220 +/- 0.008 (stat.) +/- 0.007 (syst.) where the values quoted for phi(s) and Delta Gamma(s) correspond to the solution compatible with the external measurements to which the strong phase delta(perpendicular to) is constrained and where is Delta Gamma(s) constrained to be positive. The fraction of S-wave KK or f(0) contamination through the decays B-s(0) -> J/psi K+K- (f(0)) is measured as well and is found to be consistent with zero. Results for phi(s) and Delta Gamma(s) are also presented as 68%, 90% and 95% likelihood contours, which show agreement with Standard Model expectations. |
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[Jackson, P.; Soni, N.] Univ Adelaide, Sch Chem & Phys, Adelaide, SA 5000, Australia |
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Springer |
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ISSN |
1126-6708 |
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Notes |
WOS:000313124000007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1313 |
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Author |
Agarwalla, S.K.; Prakash, S.; Raut, S.K.; Sankar, S.U. |
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Title |
Potential of optimized NOvA for large theta(13) and combined performance with a LArTPC & T2K |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
075 - 21pp |
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Keywords |
Neutrino Physics; CP violation |
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Abstract |
NO nu A experiment has reoptimized its event selection criteria in light of the recently measured moderately large value of theta(13). We study the improvement in the sensitivity to the neutrino mass hierarchy and to leptonic CP violation due to these new features. For favourable values of delta(CP), NO nu A sensitivity to mass hierarchy and leptonic CP violation is increased by 20%. Addition of 5 years of neutrino data from T2K to NO nu A more than doubles the range of delta(CP) for which the leptonic CP violation can be discovered,compared to stand alone NO nu A. But for unfavourable values of delta(CP), the combination of NO nu A and T2K are not enough to provide even a 90% C.L. hint of hierarchy discovery. Therefore,we further explore the improvement in the hierarchy and CP violation sensitivities due to the addition of a 10 kt liquid argon detector placed close to NO nu A site. The capabilities of such a detector are equivalent to those of NO nu A in all respects. We find that combined data from 10 kt liquid argon detector (3 years of nu + 3 years of (nu) over bar run), NO nu A (6 years of nu + 6 years of nu run) and T2K (5 years of nu run) can give a close to 2 sigma hint of hierarchy discovery for all values of delta(CP). With this combined data,we can achieve CP violation discovery at 95% C.L. for roughly 60% values of delta(CP). |
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Address |
[Agarwalla, Sanjib Kumar] Univ Valencia, CSIC, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: Sanjib.Agarwalla@ific.uv.es; |
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Springer |
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English |
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ISSN |
1126-6708 |
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Conference |
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Notes |
WOS:000313124000010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1316 |
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Author |
Agarwalla, S.K.; Lombardi, F.; Takeuchi, T. |
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Title |
Constraining non-standard interactions of the neutrino with Borexino |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
079 - 21pp |
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Keywords |
Neutrino Physics; Solar and Atmospheric Neutrinos; Beyond Standard Model |
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Abstract |
We use the Borexino 153.6 ton.year data to place constraints on non-standard neutrino-electron interactions, taking into account the uncertainties in the Be-7 solar neutrino flux and the mixing angle theta(23), and backgrounds due to Kr-85 and Bi-210 beta-decay. We find that the bounds are comparable to existing bounds from all other experiments. Further improvement can be expected in Phase II of Borexino due to the reduction in the Kr-85 background. |
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Address |
[Agarwalla, Sanjib Kumar] Univ Valencia, CSIC, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: Sanjib.Agarwalla@ific.uv.es; |
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Springer |
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English |
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ISSN |
1126-6708 |
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Notes |
WOS:000313124000014 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1317 |
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