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Author |
Bordes, J.; Dominguez, C.A.; Moodley, P.; Peñarrocha, J.; Schilcher, K. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Chiral corrections to the SU(2) x SU(2) Gell-Mann-Oakes-Renner relation |
Type |
Journal Article |
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Year |
2010 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
05 |
Issue |
5 |
Pages |
064 - 16pp |
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Keywords |
QCD Phenomenology |
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Abstract |
The next to leading order chiral corrections to the SU(2) x SU(2) Gell-Mann-Oakes- Renner (GMOR) relation are obtained using the pseudoscalar correlator to five-loop order in perturbative QCD, together with new finite energy sum rules (FESR) incorporating polynomial, Legendre type, integration kernels. The purpose of these kernels is to suppress hadronic contributions in the region where they are least known. This reduces considerably the systematic uncertainties arising from the lack of direct experimental information on the hadronic resonance spectral function. Three different methods are used to compute the FESR contour integral in the complex energy (squared) s-plane, i.e. Fixed Order Perturbation Theory, Contour Improved Perturbation Theory, and a fixed renormalization scale scheme. We obtain for the corrections to the GMOR relation, delta(pi), the value delta(pi) = (6.2 +/- 1.6)%. This result is substantially more accurate than previous determinations based on QCD sum rules; it is also more reliable as it is basically free of systematic uncertainties. It implies a light quark condensate < 0 vertical bar(u) over baru vertical bar 0 > similar or equal to < 0 vertical bar(d) over bard vertical bar 0 > < 0 vertical bar(q) over barq vertical bar 0 >vertical bar(2GeV) = (-267 +/- 5MeV)(3). As a byproduct, the chiral perturbation theory (unphysical) low energy constant H-2(r) is predicted to be H-2(r)(nu(X) = M-p) = -(5.1 +/- 1.8) x10(-3), or H-2(r) (nu(X) = M-eta) = -(5.7 +/- 2.0) x10(-3). |
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Address |
[Bordes, J.; Penarrocha, J.] Univ Valencia, Dept Fis Teor, CSICE, E-46100 Burjassot, Spain, Email: bordes@uv.es |
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Springer |
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English |
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ISSN ![sorted by ISSN field, ascending order (up)](img/sort_asc.gif) |
1126-6708 |
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ISI:000278250000044 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
434 |
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Permanent link to this record |
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Author |
Bridges, M.; Cranmer, K.; Feroz, F.; Hobson, M.; Ruiz de Austri, R.; Trotta, R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
A coverage study of the CMSSM based on ATLAS sensitivity using fast neural networks techniques |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
03 |
Issue |
3 |
Pages |
012 - 23pp |
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Keywords |
Supersymmetry; Phenomenology |
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Abstract |
We assess the coverage properties of confidence and credible intervals on the CMSSM parameter space inferred from a Bayesian posterior and the profile likelihood based on an ATLAS sensitivity study. In order to make those calculations feasible, we introduce a new method based on neural networks to approximate the mapping between CMSSM parameters and weak-scale particle masses. Our method reduces the computational effort needed to sample the CMSSM parameter space by a factor of similar to 10(4) with respect to conventional techniques. We find that both the Bayesian posterior and the profile likelihood intervals can significantly over-cover and identify the origin of this effect to physical boundaries in the parameter space. Finally, we point out that the effects intrinsic to the statistical procedure are conflated with simplifications to the likelihood functions from the experiments themselves. |
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Address |
[Bridges, Michael; Feroz, Farhan; Hobson, Mike] Univ Cambridge, Cavendish Lab, Astrophys Grp, Cambridge CB3 0HE, England, Email: mb435@mrao.cam.ac.uk |
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Springer |
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English |
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ISSN ![sorted by ISSN field, ascending order (up)](img/sort_asc.gif) |
1126-6708 |
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Notes |
ISI:000289295200012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
610 |
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Permanent link to this record |
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Author |
Ferrario, P.; Rodrigo, G. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Heavy colored resonances in t(t)over-bar + jet at the LHC |
Type |
Journal Article |
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Year |
2010 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
02 |
Issue |
2 |
Pages |
051 - 13pp |
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Keywords |
QCD Phenomenology |
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Abstract |
The LHC is the perfect environment for the study of new physics in the top quark sector. We study the possibility of detecting signals of heavy color-octet vector resonances, through the charge asymmetry, in t (t) over bar + jet events. Besides contributions with the t (t) over bar pair in a color-singlet state, the asymmetry gets also contributions which are proportional to the color factor f(abc)(2). This process is particularly interesting for extra-dimensional models, where the inclusive charge asymmetry generated by Kaluza-Klein excitations of the gluon vanishes at the tree level. We find that the statistical significance for the measurement of such an asymmetry is sizable for different values of the coupling constants and already at low energies. |
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Address |
[Ferrario, Paola; Rodrigo, German] UVEG, Consejo Super Invest Cient, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: paola.ferrario@ific.uv.es |
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Springer |
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English |
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ISSN ![sorted by ISSN field, ascending order (up)](img/sort_asc.gif) |
1126-6708 |
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Expedition |
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Conference |
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Notes |
ISI:000275223100051 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
483 |
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Permanent link to this record |
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Author |
Hirsch, M.; Reichert, L.; Porod, W. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Supersymmetric mass spectra and the seesaw scale |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
05 |
Issue |
5 |
Pages |
086 - 32pp |
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Keywords |
Supersymmetry Phenomenology |
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Abstract |
Supersymmetric mass spectra within two variants of the seesaw mechanism, commonly known as type-II and type-III seesaw, are calculated using full 2-loop RGEs and minimal Supergravity boundary conditions. The type-II seesaw is realized using one pair of 15 and (15) over bar superfields, while the type-III is realized using three copies of 24(M) superfields. Using published, estimated errors on SUSY mass observables attainable at the LHC and in a combined LHC+ILC analysis, we calculate expected errors for the parameters of the models, most notably the seesaw scale. If SUSY particles are within the reach of the ILC, pure mSugra can be distinguished from mSugra plus type-II or type-III seesaw for nearly all relevant values of the seesaw scale. Even in the case when only the much less accurate LHC measurements are used, we find that indications for the seesaw can be found in favourable parts of the parameter space. Since our conclusions crucially depend on the reliability of the theoretically forecasted error bars, we discuss in some detail the accuracies which need to be achieved for the most important LHC and ILC observables before an analysis, such as the one presented here, can find any hints for type-II or type-III seesaw in SUSY spectra. |
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Address |
[Hirsch, M; Reichert, L] Univ Valencia, CSIC, AHEP Grp, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: mahirsch@ific.uv.es |
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Springer |
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English |
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ISSN ![sorted by ISSN field, ascending order (up)](img/sort_asc.gif) |
1126-6708 |
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Notes |
WOS:000291364500018 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
685 |
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Permanent link to this record |
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Author |
Feroz, F.; Cranmer, K.; Hobson, M.; Ruiz de Austri, R.; Trotta, R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Challenges of profile likelihood evaluation in multi-dimensional SUSY scans |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
042 - 23pp |
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Keywords |
Supersymmetry Phenomenology |
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Abstract |
Statistical inference of the fundamental parameters of supersymmetric theories is a challenging and active endeavor. Several sophisticated algorithms have been employed to this end. While Markov-Chain Monte Carlo (MCMC) and nested sampling techniques are geared towards Bayesian inference, they have also been used to estimate frequentist confidence intervals based on the profile likelihood ratio. We investigate the performance and appropriate configuration of MULTINEST, a nested sampling based algorithm, when used for profile likelihood-based analyses both on toy models and on the parameter space of the Constrained MSSM. We find that while the standard configuration previously used in the literarture is appropriate for an accurate reconstruction of the Bayesian posterior, the profile likelihood is poorly approximated. We identify a more appropriate MULTINEST configuration for profile likelihood analyses, which gives an excellent exploration of the profile likelihood (albeit at a larger computational cost), including the identification of the global maximum likelihood value. We conclude that with the appropriate configuration MULTINEST is a suitable tool for profile likelihood studies, indicating previous claims to the contrary are not well founded. |
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Address |
[Feroz, F; Hobson, M] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England, Email: f.feroz@mrao.cam.ac.uk |
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Corporate Author |
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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 ![sorted by ISSN field, ascending order (up)](img/sort_asc.gif) |
1126-6708 |
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:000293136500042 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
745 |
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Permanent link to this record |