TH Articles

2021-05-29
08:49
 Model independent analysis of the angular observables in $B^{0} \to K^{*0} \mu^+ \mu^-$ and $B^{+} \to K^{*+} \mu^+ \mu^-$ / Hurth, T. (U. Mainz, PRISMA) ; Mahmoudi, F. (IP2I, Lyon ; CERN) ; Neshatpour, S. (IP2I, Lyon) We analyse the results recently presented on the $B^{+} \to K^{*+} \mu^+ \mu^-$ angular observables by the LHCb Collaboration which show indications for New Physics beyond the Standard Model. Within a model-independent analysis, we compare the fit results with the corresponding results for the angular observables in $B^{0} \to K^{*0} \mu^+ \mu^-$.. arXiv:2012.12207; CERN-TH-2020-222; MITP-20-085.- 2021-05-19 - 4 p. - Published in : Phys. Rev. D 103 (2021) 095020 Article from SCOAP3: PDF;

2021-05-18
08:38
 On factorisation schemes for the electron parton distribution functions in QED / Frixione, Stefano (INFN, Genoa ; CERN) The electron, positron, and photon Parton Distribution Functions (PDFs) of the unpolarised electron have recently been computed at the next-to-leading logarithmic accuracy in QED, by adopting the $\overline{\rm MS}$ factorisation scheme. We present here analogous results, obtained by working in a different framework that is inspired by the so-called DIS scheme. [...] arXiv:2105.06688; CERN-TH-2021-078.- 2021-07-23 - 32 p. - Published in : JHEP 2107 (2021) 180 Fulltext: PDF;

2021-05-12
04:00
 CMB from a Gauss-Bonnet-induced de Sitter fixed point / Kawai, Shinsuke (Sungkyunkwan U.) ; Kim, Jinsu (CERN) In the gravitational effective theories including higher curvature terms, cosmological solutions can have nontrivial de Sitter fixed points. We study phenomenological impli arXiv:2105.04386; CERN-TH-2021-075.- 2021-08-15 - 12 p. - Published in : Phys. Rev. D 104 (2021) 043525

2021-05-01
04:40
 Following in Tini’s Giant Footsteps / Ellis, John (King's Coll. London ; CERN ; NICPB, Tallinn) This paper describes my personal appreciation of some of Tini Veltman's great research achievements and how my own research career has followed the pathways he opened. Among the topics where he has been the most influential have been the pursuit and study of the Higgs boson and the calculation of radiative corrections that enabled the masses of the top quark and the Higgs boson to be predicted ahead of their discoveries. [...] arXiv:2104.14479; KCL-PH-TH/2021-27; CERN-TH-2021-067.- 2021 - 13 p. - Published in : Acta Phys. Pol. B 52 (2021) 561-574 Article from SCOAP3: PDF; In : Special volume of Acta Physica Polonica B commemorating Martinus Veltman, pp.561-574

2021-04-27
04:52
 Dark matter and the early Universe: a review / Arbey, A. (IP2I, Lyon ; CERN ; IUF, Paris) ; Mahmoudi, F. (IP2I, Lyon ; CERN ; IUF, Paris) Dark matter represents currently an outstanding problem in both cosmology and particle physics. In this review we discuss the possible explanations for dark matter and the experimental observables which can eventually lead to the discovery of dark matter and its nature, and demonstrate the close interplay between the cosmological properties of the early Universe and the observables used to constrain dark matter models in the context of new physics beyond the Standard Model.. arXiv:2104.11488; CERN-TH-2021-066.- 2021-07 - 41 p. - Published in : Prog. Part. Nucl. Phys. 119 (2021) 103865 Fulltext: PDF;

2021-04-22
11:42
 Non-abelian infrared divergences on the celestial sphere / Magnea, Lorenzo (CERN ; INFN, Turin ; Turin U.) We consider the infrared factorisation of non-abelian multi-particle scattering amplitudes, and we study the form of the universal colour operator responsible for infrared divergences, when expressed in terms of coordinates on the `celestial sphere' intersecting the future light-cone at asymptotic distances. We find that colour-dipole contributions to the infrared operator, to all orders in perturbation theory, have a remarkably simple expression in these coordinates, with scale and coupling dependence factorised from kinematics and colour. [...] arXiv:2104.10254; CERN-TH-2021-063.- 2021-05-31 - 23 p. - Published in : JHEP 2105 (2021) 282 Article from SCOAP3: PDF; Fulltext: PDF;

2021-04-15
05:11
 Precision calculation of dark radiation from spinning primordial black holes and early matter-dominated eras / Arbey, Alexandre (IP2I, Lyon ; CERN ; IUF, Paris) ; Auffinger, Jérémy (IP2I, Lyon) ; Sandick, Pearl (Utah U.) ; Shams Es Haghi, Barmak (Utah U.) ; Sinha, Kuver (Oklahoma U.) We present precision calculations of dark radiation in the form of gravitons coming from Hawking evaporation of spinning primordial black holes (PBHs) in the early Universe. Our calculation incorporates a careful treatment of extended spin distributions of a population of PBHs, the PBH reheating temperature, and the number of relativistic degrees of freedom. [...] arXiv:2104.04051; CERN-TH-2021-049.- 2021-06-15 - 18 p. - Published in : Phys. Rev. D 103 (2021) 123549 Fulltext from publisher: PDF;

2021-04-13
04:41
 Classical Gravity from Loop Amplitudes / Bjerrum-Bohr, N. Emil J. (Bohr Inst.) ; Damgaard, Poul H. (Bohr Inst. ; CERN) ; Planté, Ludovic (Unlisted, FR) ; Vanhove, Pierre (IPhT, Saclay ; Higher Sch. of Economics, Moscow ; CERN) We describe an efficient method for extracting the parts of $D$-dimensional loop integrals that are needed to derive observables in classical general relativity from scattering amplitudes. Our approach simplifies the soft-region method of integration by judiciously combining terms before the final integrations. [...] arXiv:2104.04510; IPhT-t21/015; CERN-TH-2021-052.- 2021-07-15 - 42 p. - Published in : Phys. Rev. D 104 (2021) 026009 Fulltext from publisher: PDF;

2021-04-10
04:18
 Swampland Conjectures and Infinite Flop Chains / Brodie, Callum R. (IPhT, Saclay) ; Constantin, Andrei (Oxford U., Theor. Phys. ; U. Oxford (main)) ; Lukas, Andre (Oxford U., Theor. Phys.) ; Ruehle, Fabian (CERN ; Oxford U., Theor. Phys.) We investigate swampland conjectures for quantum gravity in the context of M-theory compactified on Calabi-Yau threefolds which admit infinite sequences of flops. Naively, the moduli space of such compactifications contains paths of arbitrary geodesic length traversing an arbitrarily large number of Kähler cones, along which the low-energy spectrum remains virtually unchanged. [...] arXiv:2104.03325; CERN-TH-2021-051.- 2021-08-04 - 9 p. - Published in : Phys. Rev. D 104 (2021) 046008 Fulltext from publisher: PDF;

2021-04-09
04:02
 The eikonal approach to gravitational scattering and radiation at $\mathcal{O}$(G$^{3}$) / Di Vecchia, Paolo (Bohr Inst. ; Nordita ; Royal Inst. Tech., Stockholm) ; Heissenberg, Carlo (Nordita ; Royal Inst. Tech., Stockholm ; Uppsala U.) ; Russo, Rodolfo (Queen Mary, U. of London) ; Veneziano, Gabriele (CERN ; College de France) Using $\mathcal N=8$ supergravity as a theoretical laboratory, we extract the 3PM gravitational eikonal for two colliding massive scalars from the classical limit of the corresponding elastic two-loop amplitude. We employ the eikonal phase to obtain the physical deflection angle and to show how its non-relativistic (NR) and ultra-relativistic (UR) regimes are smoothly connected. [...] arXiv:2104.03256; CERN-TH-2021-046; NORDITA 2021-028; QMUL-PH-21-17.- 2021-07-22 - 88 p. - Published in : JHEP 2107 (2021) 169 Fulltext: PDF;