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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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Publisher |
Springer |
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Language |
English |
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ISSN |
1126-6708 |
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Conference |
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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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Permanent link to this record |
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Author |
Kittel, O.; Pilaftsis, A. |
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Title |
CP violation in correlated production and decay of unstable particles |
Type |
Journal Article |
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Year |
2012 |
Publication |
Nuclear Physics B |
Abbreviated Journal |
Nucl. Phys. B |
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Volume |
856 |
Issue |
3 |
Pages |
682-697 |
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Keywords |
EPR correlation; Resonant CP violation; Collider phenomenology |
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Abstract |
We study resonant CP-violating Einstein-Podolsky-Rosen correlations that may take place in the production and decay of unstable scalar particles at high-energy colliders. We show that as a consequence of unitarity and CPT invariance of the S-matrix, in 2 -> 2 scatterings mediated by mixed scalar particles, at least three linearly independent decay matrices associated with the unstable scalar states are needed to obtain non-zero CP-odd observables that are also odd under C-conjugation. Instead, for the correlated production and decay of two unstable particle systems in 2 -> 4 processes, we find that only two independent decay matrices are sufficient to induce a net non-vanishing CP-violating phenomenon. As an application of this theorem, we present numerical estimates of CP asymmetries for the correlated production and decay of supersymmetric scalar top anti-top pairs at the LHC, and demonstrate that these could reach values of order one. As a byproduct of our analysis, we develop a novel spinorial trace technique, which enables us to efficiently evaluate lengthy expressions of squared amplitudes describing the resonant scalar transitions. |
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Address |
[Kittel, Olaf] Univ Granada, Dept Fis Teor & Cosmos, E-18071 Granada, Spain, Email: kittel@th.physik.uni-bonn.de |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
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ISSN |
0550-3213 |
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Notes |
WOS:000300028200004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
892 |
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Author |
Kim, J.S.; Reuter, J.; Rolbiecki, K.; Ruiz de Austri, R. |
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Title |
A resonance without resonance: Scrutinizing the diphoton excess at 750 GeV |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
755 |
Issue |
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Pages |
403-408 |
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Keywords |
BSM phenomenology; LHC |
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Abstract |
Motivated by the recent diphoton excesses reported by both ATLAS and CMS collaborations, we suggest that a new heavy spinless particle is produced in gluon fusion at the LHC and decays to a couple of lighter pseudoscalars which then decay to photons. The new resonances could arise from a new strongly interacting sector and couple to Standard Model gauge bosons only via the corresponding Wess-Zumino-Witten anomaly. We present a detailed recast of the newest 13 TeV data from ATLAS and CMS together with the 8 TeV data to scan the consistency of the parameter space for those resonances. |
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Address |
[Kim, Jong Soo; Rolbiecki, Krzysztof] UAM CSIC, Inst Fis Teor, Madrid, Spain, Email: jong.kim@csic.es; |
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Publisher |
Elsevier Science Bv |
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Language |
English |
Summary Language |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000373568100059 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2713 |
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Permanent link to this record |
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Author |
Kersten, J.; Park, J.H.; Stockinger, D.; Velasco-Sevilla, L. |
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Title |
Understanding the correlation between (g-2)(mu) and μ-> e gamma in the MSSM |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
08 |
Issue |
8 |
Pages |
118 - 32pp |
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Keywords |
Supersymmetry Phenomenology |
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Abstract |
The supersymmetric contributions to the muon anomalous magnetic moment a and to the decay μ-> e gamma are given by very similar Feynman diagrams. Previous works reported correlations in specific scenarios, in particular if alpha(mu) is dominated by a single diagram. In this work we give an extensive survey of the possible correlations. We discuss examples of single-diagram domination with particularly strong correlations, and provide corresponding benchmark parameter points. We show how the correlations are weakened by significant cancellations between diagrams in large parts of the MSSM parameter space. Nevertheless, the order of magnitude of BR(mu -> e gamma) for a fixed flavor-violating parameter can often be predicted. We summarize the behavior by plotting the correlations as well as resulting bounds on the flavor-violating parameters under various assumptions on the MSSM spectrum. |
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Address |
[Kersten, Joern; Velasco-Sevilla, Liliana] Univ Hamburg, Inst Theoret Phys 2, D-22761 Hamburg, Germany, Email: joern.kersten@desy.de; |
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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:000341002400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1904 |
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Permanent link to this record |
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Author |
Kalliokoski, M.; Mitsou, V.A.; de Montigny, M.; Mukhopadhyay, A.; Ouimet, P.P.A.; Pinfold, J.; Shaa, A.; Staelens, M. |
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Title |
Searching for minicharged particles at the energy frontier with the MoEDAL-MAPP experiment at the LHC |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
04 |
Issue |
4 |
Pages |
137 - 22pp |
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Keywords |
Dark Matter at Colliders; Models for Dark Matter; New Gauge Interactions; Specific BSM Phenomenology |
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Abstract |
The MoEDAL's Apparatus for Penetrating Particles (MAPP) Experiment is designed to expand the search for new physics at the LHC, significantly extending the physics program of the baseline MoEDAL Experiment. The Phase-1 MAPP detector (MAPP-1) is currently undergoing installation at the LHC's UA83 gallery adjacent to the LHCb/MoEDAL region at Interaction Point 8 and will begin data-taking in early 2024. The focus of the MAPP experiment is on the quest for new feebly interacting particles – avatars of new physics with extremely small Standard Model couplings, such as minicharged particles (mCPs). In this study, we present the results of a comprehensive analysis of MAPP-1's sensitivity to mCPs arising in the canonical model involving the kinetic mixing of a massless dark U(1) gauge field with the Standard Model hypercharge gauge field. We focus on several dominant production mechanisms of mCPs at the LHC across the mass-mixing parameter space of interest to MAPP: Drell-Yan pair production, direct decays of heavy quarkonia and light vector mesons, and single Dalitz decays of pseudoscalar mesons. The 95% confidence level background-free sensitivity of MAPP-1 for mCPs produced at the LHC's Run 3 and the HL-LHC through these mechanisms, along with projected constraints on the minicharged strongly interacting dark matter window, are reported. Our results indicate that MAPP-1 exhibits sensitivity to sizable regions of unconstrained parameter space and can probe effective charges as low as 8 x 10 -4 e and 6 x 10 -4 e for Run 3 and the HL-LHC, respectively. |
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Address |
[Kalliokoski, Matti] Univ Helsinki, Helsinki Inst Phys, Helsinki 00014, Finland, Email: matti.kalliokoski@helsinki.fi; |
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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 |
1029-8479 |
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:001232666600002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6148 |
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Permanent link to this record |