Abstract
We consider top-antitop quark (\( t\overline{t} \)) production at the Large Hadron Collider (LHC) with subsequent decay into dileptonic and lepton plus jets final states. We present a set of leptonic angular correlations and distributions with which experiments can probe all the independent coefficient functions of the top-spin dependent parts of the \( t\overline{t} \) production spin density matrices. We compute these angular correlations and distributions for LHC center-of-mass energies 8, 13, and 14 TeV within the Standard Model at next-to-leading order in the QCD coupling including the mixed QCD-weak corrections and for the transverse top-quark polarization and the \( t\overline{t} \) charge asymmetry also the mixed QCD-QED corrections. In addition we analyze and compute the effects of new interactions on these observables in terms of a gauge-invariant effective Lagrangian that contains all operators relevant for hadronic \( t\overline{t} \) production up to mass dimension six.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
CDF collaboration, T. Aaltonen et al., Measurement of \( t\overline{t} \) Spin Correlation in \( p\overline{p} \) Collisions Using the CDF II Detector at the Tevatron, Phys. Rev. D 83 (2011) 031104 [arXiv:1012.3093] [INSPIRE].
D0 collaboration, V.M. Abazov et al., Measurement of spin correlation in \( t\overline{t} \) production using a matrix element approach, Phys. Rev. Lett. 107 (2011) 032001 [arXiv:1104.5194] [INSPIRE].
D0 collaboration, V.M. Abazov et al., Evidence for spin correlation in \( t\overline{t} \) production, Phys. Rev. Lett. 108 (2012) 032004 [arXiv:1110.4194] [INSPIRE].
D0 collaboration, V.M. Abazov et al., Measurement of Leptonic Asymmetries and Top Quark Polarization in \( t\overline{t} \) Production, Phys. Rev. D 87 (2013) 011103 [arXiv:1207.0364] [INSPIRE].
ATLAS collaboration, Observation of spin correlation in \( t\overline{t} \) events from pp collisions at \( \sqrt{s}=7 \) TeV using the ATLAS detector, Phys. Rev. Lett. 108 (2012) 212001 [arXiv:1203.4081] [INSPIRE].
ATLAS collaboration, Measurement of Top Quark Polarization in Top-Antitop Events from Proton-Proton Collisions at \( \sqrt{s}=7 \) TeV Using the ATLAS Detector, Phys. Rev. Lett. 111 (2013) 232002 [arXiv:1307.6511] [INSPIRE].
CMS collaboration, Measurements of \( t\overline{t} \) spin correlations and top-quark polarization using dilepton final states in pp collisions at \( \sqrt{s}=7 \) TeV, Phys. Rev. Lett. 112 (2014) 182001 [arXiv:1311.3924] [INSPIRE].
ATLAS collaboration, Measurements of spin correlation in top-antitop quark events from proton-proton collisions at \( \sqrt{s}=7 \) TeV using the ATLAS detector, Phys. Rev. D 90 (2014) 112016 [arXiv:1407.4314] [INSPIRE].
CMS Collaboration, Search for Anomalous Top Chromomagnetic Dipole Moments from angular distributions in \( t\overline{t} \) Dileptonic events at \( \sqrt{s}=7 \) TeV with the CMS detector, CMS-PAS-TOP-14-005 (2014) [INSPIRE].
ATLAS collaboration, Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at \( \sqrt{s}=8 \) TeV Using the ATLAS Detector, Phys. Rev. Lett. 114 (2015) 142001 [arXiv:1412.4742] [INSPIRE].
CMS Collaboration, Measurement of spin correlations in top pair events in the lepton + jets channel with the matrix element method at 8 TeV, CMS-PAS-TOP-13-015 (2015) [INSPIRE].
W. Bernreuther, A. Brandenburg, Z.-G. Si and P. Uwer, Top quark spin correlations at hadron colliders: Predictions at next-to-leading order QCD, Phys. Rev. Lett. 87 (2001) 242002 [hep-ph/0107086] [INSPIRE].
W. Bernreuther, A. Brandenburg, Z.-G. Si and P. Uwer, Top quark pair production and decay at hadron colliders, Nucl. Phys. B 690 (2004) 81 [hep-ph/0403035] [INSPIRE].
W. Bernreuther and Z.-G. Si, Distributions and correlations for top quark pair production and decay at the Tevatron and LHC, Nucl. Phys. B 837 (2010) 90 [arXiv:1003.3926] [INSPIRE].
W. Bernreuther and Z.-G. Si, Top quark spin correlations and polarization at the LHC: standard model predictions and effects of anomalous top chromo moments, Phys. Lett. B 725 (2013) 115 [Corrigendum ibid. 744 (2015) 413] [arXiv:1305.2066] [INSPIRE].
W. Buchmüller and D. Wyler, Effective Lagrangian Analysis of New Interactions and Flavor Conservation, Nucl. Phys. B 268 (1986) 621 [INSPIRE].
B. Grzadkowski, M. Iskrzynski, M. Misiak and J. Rosiek, Dimension-Six Terms in the Standard Model Lagrangian, JHEP 10 (2010) 085 [arXiv:1008.4884] [INSPIRE].
J.A. Aguilar-Saavedra, A Minimal set of top anomalous couplings, Nucl. Phys. B 812 (2009) 181 [arXiv:0811.3842] [INSPIRE].
J.A. Aguilar-Saavedra, A Minimal set of top-Higgs anomalous couplings, Nucl. Phys. B 821 (2009) 215 [arXiv:0904.2387] [INSPIRE].
C. Zhang and S. Willenbrock, Effective-Field-Theory Approach to Top-Quark Production and Decay, Phys. Rev. D 83 (2011) 034006 [arXiv:1008.3869] [INSPIRE].
J.A. Aguilar-Saavedra, Effective four-fermion operators in top physics: A Roadmap, Nucl. Phys. B 843 (2011) 638 [Erratum ibid. B 851 (2011) 443] [arXiv:1008.3562] [INSPIRE].
C. Degrande, J.-M. Gerard, C. Grojean, F. Maltoni and G. Servant, Non-resonant New Physics in Top Pair Production at Hadron Colliders, JHEP 03 (2011) 125 [arXiv:1010.6304] [INSPIRE].
D. Atwood, A. Aeppli and A. Soni, Extracting anomalous gluon-top effective couplings at the supercolliders, Phys. Rev. Lett. 69 (1992) 2754 [INSPIRE].
A. Brandenburg and J.P. Ma, CP odd observables for the top-antitop system produced at proton-antiproton and proton-proton colliders, Phys. Lett. B 298 (1993) 211 [INSPIRE].
D. Atwood, A. Kagan and T.G. Rizzo, Constraining anomalous top quark couplings at the Tevatron, Phys. Rev. D 52 (1995) 6264 [hep-ph/9407408] [INSPIRE].
P. Haberl, O. Nachtmann and A. Wilch, Top production in hadron hadron collisions and anomalous top-gluon couplings, Phys. Rev. D 53 (1996) 4875 [hep-ph/9505409] [INSPIRE].
K.-m. Cheung, Probing the chromoelectric and chromomagnetic dipole moments of the top quark at hadronic colliders, Phys. Rev. D 53 (1996) 3604 [hep-ph/9511260] [INSPIRE].
K.-m. Cheung, Probing nonstandard top couplings using spin correlation, Phys. Rev. D 55 (1997) 4430 [hep-ph/9610368] [INSPIRE].
B. Grzadkowski, B. Lampe and K.J. Abraham, CP violation, top quarks and the Tevatron upgrade, Phys. Lett. B 415 (1997) 193 [hep-ph/9706489] [INSPIRE].
J.M. Yang and B.-L. Young, Dimension-six CP-violating operators of the third family quarks and their effects at colliders, Phys. Rev. D 56 (1997) 5907 [hep-ph/9703463] [INSPIRE].
K.-i. Hikasa, K. Whisnant, J.M. Yang and B.-L. Young, Probing anomalous top quark interactions at the Fermilab Tevatron collider, Phys. Rev. D 58 (1998) 114003 [hep-ph/9806401] [INSPIRE].
H.-Y. Zhou, CP violation in top quark pair production at hadron colliders, Phys. Rev. D 58 (1998) 114002 [hep-ph/9805358] [INSPIRE].
D. Atwood, S. Bar-Shalom, G. Eilam and A. Soni, CP violation in top physics, Phys. Rept. 347 (2001) 1 [hep-ph/0006032] [INSPIRE].
R. Martinez and J.A. Rodriguez, The Anomalous chromomagnetic dipole moment of the top quark in the standard model and beyond, Phys. Rev. D 65 (2002) 057301 [hep-ph/0109109] [INSPIRE].
B. Lillie, J. Shu and T.M.P. Tait, Top Compositeness at the Tevatron and LHC, JHEP 04 (2008) 087 [arXiv:0712.3057] [INSPIRE].
S.K. Gupta and G. Valencia, CP-odd correlations using jet momenta from \( t\overline{t} \) events at the Tevatron, Phys. Rev. D 81 (2010) 034013 [arXiv:0912.0707] [INSPIRE].
S.K. Gupta, A.S. Mete and G. Valencia, CP violating anomalous top-quark couplings at the LHC, Phys. Rev. D 80 (2009) 034013 [arXiv:0905.1074] [INSPIRE].
Z. Hioki and K. Ohkuma, Search for anomalous top-gluon couplings at LHC revisited, Eur. Phys. J. C 65 (2010) 127 [arXiv:0910.3049] [INSPIRE].
Z. Hioki and K. Ohkuma, Exploring anomalous top interactions via the final lepton in \( t\overline{t} \) productions/decays at hadron colliders, Phys. Rev. D 83 (2011) 114045 [arXiv:1104.1221] [INSPIRE].
D. Choudhury and P. Saha, Probing Top Anomalous Couplings at the Tevatron and the Large Hadron Collider, Pramana 77 (2011) 1079 [arXiv:0911.5016] [INSPIRE].
J. Cao, K. Hikasa, L. Wang, L. Wu and J.M. Yang, Testing new physics models by top charge asymmetry and polarization at the LHC, Phys. Rev. D 85 (2012) 014025 [arXiv:1109.6543] [INSPIRE].
J.F. Kamenik, M. Papucci and A. Weiler, Constraining the dipole moments of the top quark, Phys. Rev. D 85 (2012) 071501 [arXiv:1107.3143] [INSPIRE].
F. Bach and T. Ohl, Anomalous Top Couplings at Hadron Colliders Revisited, Phys. Rev. D 86 (2012) 114026 [arXiv:1209.4564] [INSPIRE].
E. Gabrielli, A. Racioppi, M. Raidal and H. Veermae, Implications of effective axial-vector coupling of gluon for tt spin polarizations at the LHC, Phys. Rev. D 87 (2013) 054001 [arXiv:1212.3272] [INSPIRE].
Z. Hioki and K. Ohkuma, Optimal-observable Analysis of Possible Non-standard Top-quark Couplings in \( pp\to t\overline{t}X\to {l}^{+}{X}^{\prime } \), Phys. Lett. B 716 (2012) 310 [arXiv:1206.2413] [INSPIRE].
C. Englert, A. Freitas, M. Spira and P.M. Zerwas, Constraining the Intrinsic Structure of Top-Quarks, Phys. Lett. B 721 (2013) 261 [arXiv:1210.2570] [INSPIRE].
S.S. Biswal, S.D. Rindani and P. Sharma, Probing chromomagnetic and chromoelectric couplings of the top quark using its polarization in pair production at hadron colliders, Phys. Rev. D 88 (2013) 074018 [arXiv:1211.4075] [INSPIRE].
M. Baumgart and B. Tweedie, A New Twist on Top Quark Spin Correlations, JHEP 03 (2013) 117 [arXiv:1212.4888] [INSPIRE].
S.Y. Ayazi, H. Hesari and M.M. Najafabadi, Probing the top quark chromoelectric and chromomagnetic dipole moments in single top tW -channel at the LHC, Phys. Lett. B 727 (2013) 199 [arXiv:1307.1846] [INSPIRE].
Z. Hioki and K. Ohkuma, Latest constraint on nonstandard top-gluon couplings at hadron colliders and its future prospect, Phys. Rev. D 88 (2013) 017503 [arXiv:1306.5387] [INSPIRE].
M. Fabbrichesi, M. Pinamonti and A. Tonero, Stringent limits on top-quark compositeness from \( t\overline{t} \) production at the Tevatron and the LHC, Phys. Rev. D 89 (2014) 074028 [arXiv:1307.5750] [INSPIRE].
G. Bélanger, R.M. Godbole, L. Hartgring and I. Niessen, Top Polarization in Stop Production at the LHC, JHEP 05 (2013) 167 [arXiv:1212.3526] [INSPIRE].
A. Hayreter and G. Valencia, Constraints on anomalous color dipole operators from Higgs boson production at the LHC, Phys. Rev. D 88 (2013) 034033 [arXiv:1304.6976] [INSPIRE].
M. König, M. Neubert and D.M. Straub, Dipole operator constraints on composite Higgs models, Eur. Phys. J. C 74 (2014) 2945 [arXiv:1403.2756] [INSPIRE].
J.A. Aguilar-Saavedra, B. Fuks and M.L. Mangano, Pinning down top dipole moments with ultra-boosted tops, Phys. Rev. D 91 (2015) 094021 [arXiv:1412.6654] [INSPIRE].
I.D. Choudhury and A. Lahiri, Anomalous chromomagnetic moment of quarks, Mod. Phys. Lett. A 30 (2015) 1550113 [arXiv:1409.0073] [INSPIRE].
K. Kiers, P. Saha, A. Szynkman, D. London, S. Judge and J. Melendez, Search for New Physics in Rare Top Decays: \( t\overline{t} \) Spin Correlations and Other Observables, Phys. Rev. D 90 (2014) 094015 [arXiv:1407.1724] [INSPIRE].
A.V. Prasath, R.M. Godbole and S.D. Rindani, Longitudinal top polarisation measurement and anomalous W tb coupling, Eur. Phys. J. C 75 (2015) 402 [arXiv:1405.1264] [INSPIRE].
B. Tweedie, Better Hadronic Top Quark Polarimetry, Phys. Rev. D 90 (2014) 094010 [arXiv:1401.3021] [INSPIRE].
A. Carmona et al., From Tevatron’s top and lepton-based asymmetries to the LHC, JHEP 07 (2014) 005 [arXiv:1401.2443] [INSPIRE].
C. Zhang, Effective field theory approach to top-quark decay at next-to-leading order in QCD, Phys. Rev. D 90 (2014) 014008 [arXiv:1404.1264] [INSPIRE].
H. Hesari and M. Mohammadi Najafabadi, Direct photon production as a probe of quarks chromoelectric and chromomagnetic dipole moments at the LHC, Phys. Rev. D 91 (2015) 057502 [arXiv:1407.5887] [INSPIRE].
A. Kobakhidze, L. Wu and J. Yue, Anomalous Top-Higgs Couplings and Top Polarisation in Single Top and Higgs Associated Production at the LHC, JHEP 10 (2014) 100 [arXiv:1406.1961] [INSPIRE].
Z. Hioki and K. Ohkuma, Final charged-lepton angular distribution and possible anomalous top-quark couplings in \( pp\to t\overline{t}X\to {\ell}^{+}{X}^{\prime } \), Phys. Lett. B 736 (2014) 1 [arXiv:1406.2475] [INSPIRE].
S. Jung, P. Ko, Y.W. Yoon and C. Yu, Renormalization group-induced phenomena of top pairs from four-quark effective operators, JHEP 08 (2014) 120 [arXiv:1406.4570] [INSPIRE].
R. Gaitan, E.A. Garces, J.H.M. de Oca and R. Martinez, Top quark Chromoelectric and Chromomagnetic Dipole Moments in a Two Higgs Doublet Model with CP-violation, arXiv:1505.04168 [INSPIRE].
R.M. Godbole, G. Mendiratta and S. Rindani, Looking for BSM physics using top-quark polarization and decay-lepton kinematic asymmetries, Phys. Rev. D 92 (2015) 094013 [arXiv:1506.07486] [INSPIRE].
D. Buarque Franzosi and C. Zhang, Probing the top-quark chromomagnetic dipole moment at next-to-leading order in QCD, Phys. Rev. D 91 (2015) 114010 [arXiv:1503.08841] [INSPIRE].
S.D. Rindani, P. Sharma and A.W. Thomas, Polarization of top quark as a probe of its chromomagnetic and chromoelectric couplings in tW production at the Large Hadron Collider, JHEP 10 (2015) 180 [arXiv:1507.08385] [INSPIRE].
A. Buckley et al., A global fit of top quark effective theory to data, arXiv:1506.08845 [INSPIRE].
J. de Blas, M. Chala and J. Santiago, Renormalization Group Constraints on New Top Interactions from Electroweak Precision Data, JHEP 09 (2015) 189 [arXiv:1507.00757] [INSPIRE].
M. Czakon, P. Fiedler and A. Mitov, Total Top-Quark Pair-Production Cross Section at Hadron Colliders Through O(α 4 S ), Phys. Rev. Lett. 110 (2013) 252004 [arXiv:1303.6254] [INSPIRE].
W. Bernreuther and A. Brandenburg, Tracing CP-violation in the production of top quark pairs by multiple TeV proton proton collisions, Phys. Rev. D 49 (1994) 4481 [hep-ph/9312210] [INSPIRE].
S.D. Rindani, Effect of anomalous tbW vertex on decay lepton distributions in \( {e}^{+}{e}^{-}\to t\overline{t} \) and CP-violating asymmetries, Pramana 54 (2000) 791[hep-ph/0002006] [INSPIRE].
B. Grzadkowski and Z. Hioki, New hints for testing anomalous top quark interactions at future linear colliders, Phys. Lett. B 476 (2000) 87 [hep-ph/9911505] [INSPIRE].
B. Grzadkowski and Z. Hioki, Decoupling of anomalous top decay vertices in angular distribution of secondary particles, Phys. Lett. B 557 (2003) 55 [hep-ph/0208079] [INSPIRE].
R.M. Godbole, S.D. Rindani and R.K. Singh, Lepton distribution as a probe of new physics in production and decay of the t quark and its polarization, JHEP 12 (2006) 021 [hep-ph/0605100] [INSPIRE].
M. Fabbrichesi, M. Pinamonti and A. Tonero, Limits on anomalous top quark gauge couplings from Tevatron and LHC data, Eur. Phys. J. C 74 (2014) 3193 [arXiv:1406.5393] [INSPIRE].
Q.-H. Cao, B. Yan, J.-H. Yu and C. Zhang, A General Analysis of W tb anomalous Couplings, arXiv:1504.03785 [INSPIRE].
A. Brandenburg, Z.-G. Si and P. Uwer, QCD corrected spin analyzing power of jets in decays of polarized top quarks, Phys. Lett. B 539 (2002) 235 [hep-ph/0205023] [INSPIRE].
R. Martinez and J.A. Rodriguez, Using the radiative decay b → sγ to bound the chromomagnetic dipole moment of the top quark, Phys. Rev. D 55 (1997) 3212 [hep-ph/9612438] [INSPIRE].
W. Hollik and M. Kollar, NLO QED contributions to top-pair production at hadron collider, Phys. Rev. D 77 (2008) 014008 [arXiv:0708.1697] [INSPIRE].
H.-L. Lai et al., New parton distributions for collider physics, Phys. Rev. D 82 (2010) 074024 [arXiv:1007.2241] [INSPIRE].
ATLAS collaboration, Combination of ATLAS and CMS top quark pair cross section measurements in the eμ final state using proton-proton collisions at \( \sqrt{s}=8 \) TeV, ATLAS-CONF-2014-054 (2014) [INSPIRE].
M. Czakon and A. Mitov, Top++: A Program for the Calculation of the Top-Pair Cross-Section at Hadron Colliders, Comput. Phys. Commun. 185 (2014) 2930 [arXiv:1112.5675] [INSPIRE].
W. Bernreuther and Z.-G. Si, Top quark and leptonic charge asymmetries for the Tevatron and LHC, Phys. Rev. D 86 (2012) 034026 [arXiv:1205.6580] [INSPIRE].
J.H. Kuhn and G. Rodrigo, Charge asymmetries of top quarks at hadron colliders revisited, JHEP 01 (2012) 063 [arXiv:1109.6830] [INSPIRE].
CMS collaboration, Inclusive and differential measurements of the tt charge asymmetry in pp collisions at \( \sqrt{s}=8 \) TeV, arXiv:1507.03119 [INSPIRE].
M. Czakon, P. Fiedler and A. Mitov, Resolving the Tevatron Top Quark Forward-Backward Asymmetry Puzzle: Fully Differential Next-to-Next-to-Leading-Order Calculation, Phys. Rev. Lett. 115 (2015) 052001 [arXiv:1411.3007] [INSPIRE].
E. Gabrielli and M. Raidal, Effective axial-vector coupling of gluon as an explanation to the top quark asymmetry, Phys. Rev. D 84 (2011) 054017 [arXiv:1106.4553] [INSPIRE].
J.A. Aguilar-Saavedra and M. Pérez-Victoria, Probing the Tevatron \( t\overline{t} \) asymmetry at LHC, JHEP 05 (2011) 034 [arXiv:1103.2765] [INSPIRE].
C. Delaunay, O. Gedalia, Y. Hochberg, G. Perez and Y. Soreq, Implications of the CDF tt Forward-Backward Asymmetry for Hard Top Physics, JHEP 08 (2011) 031 [arXiv:1103.2297] [INSPIRE].
E. Gabrielli, M. Raidal and A. Racioppi, Implications of the effective axial-vector coupling of gluon on top-quark charge asymmetry at the LHC, Phys. Rev. D 85 (2012) 074021 [arXiv:1112.5885] [INSPIRE].
J.A. Aguilar-Saavedra, D. Amidei, A. Juste and M. Pérez-Victoria, Asymmetries in top quark pair production at hadron colliders, Rev. Mod. Phys. 87 (2015) 421 [arXiv:1406.1798] [INSPIRE].
W. Bernreuther, A. Brandenburg and M. Flesch, Effects of Higgs sector CP-violation in top quark pair production at the LHC, hep-ph/9812387 [INSPIRE].
W. Bernreuther, A. Brandenburg and P. Uwer, Transverse polarization of top quark pairs at the Tevatron and the large hadron collider, Phys. Lett. B 368 (1996) 153 [hep-ph/9510300] [INSPIRE].
W.G.D. Dharmaratna and G.R. Goldstein, Single quark polarization in quantum chromodynamics subprocesses, Phys. Rev. D 53 (1996) 1073 [INSPIRE].
W. Bernreuther, M. Fuecker and Z.-G. Si, Mixed QCD and weak corrections to top quark pair production at hadron colliders, Phys. Lett. B 633 (2006) 54 [hep-ph/0508091] [INSPIRE].
W. Bernreuther, M. Fuecker and Z.-G. Si, Weak interaction corrections to hadronic top quark pair production, Phys. Rev. D 74 (2006) 113005 [hep-ph/0610334] [INSPIRE].
W. Bernreuther, M. Fucker and Z.-G. Si, Weak interaction corrections to hadronic top quark pair production: Contributions from quark-gluon and bb induced reactions, Phys. Rev. D 78 (2008) 017503 [arXiv:0804.1237] [INSPIRE].
J.H. Kuhn, A. Scharf and P. Uwer, Electroweak corrections to top-quark pair production in quark-antiquark annihilation, Eur. Phys. J. C 45 (2006) 139 [hep-ph/0508092] [INSPIRE].
J.H. Kuhn, A. Scharf and P. Uwer, Electroweak effects in top-quark pair production at hadron colliders, Eur. Phys. J. C 51 (2007) 37 [hep-ph/0610335] [INSPIRE].
W. Beenakker, A. Denner, W. Hollik, R. Mertig, T. Sack and D. Wackeroth, Electroweak one loop contributions to top pair production in hadron colliders, Nucl. Phys. B 411 (1994) 343 [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1508.05271
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Bernreuther, W., Heisler, D. & Si, ZG. A set of top quark spin correlation and polarization observables for the LHC: Standard Model predictions and new physics contributions. J. High Energ. Phys. 2015, 1–36 (2015). https://doi.org/10.1007/JHEP12(2015)026
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/JHEP12(2015)026