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Bimetric, Conformal Supergravity and its Superstring Embedding
http://cds.cern.ch/record/2644282
We discuss the connection between Weyl$^2$ supergravity and superstrings and further discuss holography between 4-dimensional, ${\cal N}=4$ superconformal Weyl$^2$ supergravity and ${\cal N}=8$, higher spin-four theory on $AdS_5$. The massive Weyl$^2$ supergravity theory is a special kind of a bimetric gravity theory and consists of a massless graviton multiplet plus an additional massive spin-two supermultiplet. Here, we argue that the additional spin-two field and its superpartners originate from massive excitations in the open string sector; just like the ${\cal N}=4$ super Yang-Mills gauge fields, they are localized on the world volume of D3-branes. The ghost structure of the Weyl action should be considered as an artifact of the truncation of the infinitely many higher derivative terms underlying the massive spin 2 action. In field theory, ${\cal N}=4$ Weyl$^2$ supergravity exhibits superconformal invariance in the limit of vanishing Planck mass. In string theory the additional spin-two fields become massless in the tensionless limit. Therefore low string scale scenarios with large extra dimensions provide (almost) superconformal field theories with almost massless open string spin-two fields. The full scalar potential including the Yang-Mills matter multiplets is presented and the supersymmetric vacua of Einstein Supergravity are shown, as expected, to be vacua of massive Weyl supergravity. Other vacua are expected to exist which are not vacua of Einstein supergravity. Finally, we identify certain spin-four operators on the 4-dimensional boundary theory that could be the holographic duals of spin-four fields in the bulk.Ferrara, SergioKehagias, AlexLust, DieterSat, 20 Oct 2018 02:31:16 GMT2018-10-18CERN-TH-2018-222http://cds.cern.ch/record/26442822018222Probing $\Lambda$CDM cosmology with the Evolutionary Map of the Universe survey
http://cds.cern.ch/record/2644038
The Evolutionary Map of the Universe (EMU) is an all-sky survey in radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy angular power spectrum and the integrated Sachs-Wolfe effect, we study the potential of EMU to constrain models beyond $\Lambda$CDM (i.e., local primordial non-Gaussianity, dynamical dark energy, spatial curvature and deviations from general relativity), for different design sensitivities. We also include a multi-tracer analysis, distinguishing between star-forming galaxies and galaxies with an active galactic nucleus, to further improve EMU's potential. We find that EMU could measure the dark energy equation of state parameters around 35\% more precisely than existing constraints, and that the constraints on $f_{\rm NL}$ and modified gravity parameters will improve up to a factor $\sim2$ with respect to Planck and redshift space distortions measurements. With this work we demonstrate the promising potential of EMU to contribute to our understanding of the Universe.Bernal, José LuisRaccanelli, AlviseKovetz, Ely D.Parkinson, DavidNorris, Ray P.Danforth, GeorgeSchmitt, CourtneyThu, 18 Oct 2018 04:07:04 GMT2018-10-15arXiv:1810.06672http://cds.cern.ch/record/2644038['arXiv:1810.06672']arXiv:1810.06672Parton Shower and Matching Uncertainties in Top Quark Pair Production with Herwig 7
http://cds.cern.ch/record/2643941
We evaluate the theoretical uncertainties in next-to-leading order plus parton shower predictions for top quark pair production and decay in hadronic collisions. Our work is carried out using the Herwig 7 event generator and presents an in-depth study of variations in matching schemes with two systematically different shower algorithms, the traditional angular-ordered and alternative dipole shower. We also present all of the required extensions of the Herwig dipole shower algorithm to properly take into account quark mass effects, as well as its ability to perform top quark decays. The predictions are compared at parton level as well as to LHC data, including in the boosted regime. We find that the regions where predictions with a non-top-quark-specific tune differ drastically from data are plagued by large uncertainties which are consistent between our two shower and matching algorithms.Cormier, KylePlätzer, SimonReuschle, ChristianRichardson, PeterWebster, StephenWed, 17 Oct 2018 02:03:42 GMT2018-10-15arXiv:1810.06493http://cds.cern.ch/record/2643941['arXiv:1810.06493']arXiv:1810.06493Constraining D-foam via the 21-cm Line
http://cds.cern.ch/record/2643826
We have suggested earlier that D-particles, which are stringy space-time defects predicted in brane-inspired models of the Universe, might constitute a component of dark matter, and that they might contribute to the masses of singlet fermions that could provide another component. Interactions of the quantum-fluctuating D-particles with matter induce vector forces that are mediated by a massless effective U(1) gauge field, the "D-photon", which is distinct from the ordinary photon and has different properties from dark photons. We discuss the form of interactions of D-matter with conventional matter induced by D-photon exchange and calculate their strength, which depends on the density of D-particles. Observations of the hydrogen 21~cm line at redshifts >= 15 can constrain these interactions and the density of D-matter in the early Universe.Ellis, JohnMavromatos, Nick E.Nanopoulos, Dimitri V.Tue, 16 Oct 2018 03:02:12 GMT2018-10-12arXiv:1810.05393http://cds.cern.ch/record/2643826['arXiv:1810.05393']arXiv:1810.05393Elliptic Feynman integrals and pure functions
http://cds.cern.ch/record/2643825
We propose a variant of elliptic multiple polylogarithms that have at most logarithmic singularities in all variables and satisfy a differential equation without homogeneous term. We investigate several non-trivial elliptic two-loop Feynman integrals with up to three external legs and express them in terms of our functions. We observe that in all cases they evaluate to pure combinations of elliptic multiple polylogarithms of uniform weight. This is the first time that a notion of uniform weight is observed in the context of Feynman integrals that evaluate to elliptic polylogarithms.Broedel, JohannesDuhr, ClaudeDulat, FalkoPenante, BrendaTancredi, LorenzoTue, 16 Oct 2018 03:02:12 GMT2018-09-27arXiv:1809.10698http://cds.cern.ch/record/2643825['arXiv:1809.10698']arXiv:1809.10698Weyl anomaly and the $C$-function in $\lambda$-deformed CFTs
http://cds.cern.ch/record/2643545
For a general $\lambda$-deformation of current algebra CFTs we compute the exact Weyl anomaly coefficient and the corresponding metric in the couplings space geometry. By incorporating the exact $\beta$-function found in previous works we show that the Weyl anomaly is in fact the exact Zamolodchikov's $C$-function interpolating between exact CFTs occurring in the UV and in the IR. We provide explicit examples with the anisotropic $SU(2)$ case presented in detail. The anomalous dimension of the operator driving the deformation is also computed in general. Agreement is found with special cases existing already in the literature.Sagkrioti, EftychiaSfetsos, KonstantinosSiampos, KonstantinosSat, 13 Oct 2018 02:17:08 GMT2018-10-09arXiv:1810.04189http://cds.cern.ch/record/2643545['arXiv:1810.04189']arXiv:1810.04189Constraints on the quartic Higgs self-coupling from double-Higgs production at future hadron colliders
http://cds.cern.ch/record/2643544
We study the indirect constraints on the quartic Higgs self-coupling that arise from double-Higgs production at future hadron colliders. To this purpose, we calculate the two-loop contributions to the $gg \to hh$ amplitudes that involve a modified $h^4$ vertex. Based on our novel results, we estimate the reach of a $pp$ collider operating at $27 \, {\rm TeV}$ and $100 \, {\rm TeV}$ centre-of-mass energy in constraining the cubic and quartic Higgs self-couplings by measurements of double-Higgs and triple-Higgs production in gluon-fusion.Bizoń, WojciechHaisch, UlrichRottoli, LucaSat, 13 Oct 2018 02:17:08 GMT2018-10-10arXiv:1810.04665http://cds.cern.ch/record/2643544['arXiv:1810.04665']arXiv:1810.04665Scattering of scalar, electromagnetic and gravitational waves from binary systems
http://cds.cern.ch/record/2643284
The direct detection of gravitational waves crowns decades of efforts in the modelling of sources and of increasing detectors' sensitivity. With future third-generation Earth-based detectors or space-based observatories, gravitational-wave astronomy will be at its full bloom. Previously brushed-aside questions on environmental or other systematic effects in the generation and propagation of gravitational waves are now begging for a systematic treatment. Here, we study how electromagnetic and gravitational radiation is scattered by a binary system. Scattering cross-sections, resonances and the effect of an impinging wave on a gravitational-bound binary are worked out for the first time. The ratio between the scattered-wave amplitude and the incident wave can be of order $10^{-5}$ for known pulsars, bringing this into the realm of future gravitational-wave observatories. For currently realistic distribution of compact-object binaries, the interaction cross-section is too small to be of relevance.Annulli, LorenzoBernard, LauraBlas, DiegoCardoso, VitorThu, 11 Oct 2018 03:15:40 GMT2018-09-13arXiv:1809.05108http://cds.cern.ch/record/2643284['arXiv:1809.05108']arXiv:1809.05108Scattering of light dark matter in atomic clocks
http://cds.cern.ch/record/2641822
We present a detailed analysis of the effect of light Dark Matter (DM) on atomic clocks, for the case where DM mass and density are such that occupation numbers are low and DM must be considered as particles scattering off the atoms, rather than a classical field. We show that the resulting atomic clock frequency shifts are first order in the scattering amplitudes, and particularly suited to constrain DM models in the regime where the DM mass $m_\chi \ll$ GeV. We provide some rough order of magnitude estimates of sensitivity that can be confronted to any DM model that allows for non zero differential scattering amplitudes of the two atomic states involved in the clock.Wolf, PeterAlonso, RodrigoBlas, DiegoFri, 05 Oct 2018 02:46:05 GMT2018-10-03arXiv:1810.01632http://cds.cern.ch/record/2641822['arXiv:1810.01632']arXiv:1810.01632Exploring the ultra-light to sub-MeV dark matter window with atomic clocks and co-magnetometers
http://cds.cern.ch/record/2641654
Particle dark matter could have a mass anywhere from that of ultralight candidates, $m_\chi\sim 10^{-21}\,$eV, to scales well above the GeV. Conventional laboratory searches are sensitive to a range of masses close to the weak scale, while new techniques are required to explore candidates outside this realm. In particular lighter candidates are difficult to detect due to their small momentum. Here we study two experimental set-ups which {\it do not require transfer of momentum} to detect dark matter: atomic clocks and co-magnetometers. These experiments probe dark matter that couples to the spin of matter via the very precise measurement of the energy difference between atomic states of different angular momenta. This coupling is possible (even natural) in most dark matter models, and we translate the current experimental sensitivity into implications for different dark matter models. It is found that the constraints from current atomic clocks and co-magnetometers can be competitive in the mass range $m_\chi\sim 10^{-21}-10^3\,$eV, depending on the model. We also comment on the (negligible) effect of different astrophysical neutrino backgrounds.Alonso, RodrigoBlas, DiegoWolf, PeterThu, 04 Oct 2018 02:51:03 GMT2018-10-01arXiv:1810.00889http://cds.cern.ch/record/2641654['arXiv:1810.00889']arXiv:1810.00889Searches for gamma-ray lines and `pure WIMP' spectra from Dark Matter annihilations in dwarf galaxies with H.E.S.S
http://cds.cern.ch/record/2641652
Dwarf spheroidal galaxies are among the most promising targets for detecting signals of Dark Matter (DM) annihilations. The H.E.S.S. experiment has observed five of these systems for a total of about 130 hours. The data are re-analyzed here, and, in the absence of any detected signals, are interpreted in terms of limits on the DM annihilation cross section. Two scenarios are considered: i) DM annihilation into mono-energetic gamma-rays and ii) DM in the form of pure WIMP multiplets that, annihilating into all electroweak bosons, produce a distinctive gamma-ray spectral shape with a high-energy peak at the DM mass and a lower-energy continuum. For case i), upper limits at 95\% confidence level of about $\langle \sigma v \rangle \lesssim 3 \times 10^{-25}$ cm$^3$ s$^{-1}$ are obtained in the mass range of 400 GeV to 1 TeV. For case ii), the full spectral shape of the models is used and several excluded regions are identified, but the thermal masses of the candidates are not robustly ruled out.Abdalla, H.Aharonian, F.Ait Benkhali, F.Angüner, E.O.Arakawa, M.Arcaro, C.Armand, C.Arrieta, M.Backes, M.Barnard, M.Becherini, Y.Becker Tjus, J.Berge, D.Bernhard, S.Bernlöhr, K.Blackwell, R.Böttcher, M.Boisson, C.Bolmont, J.Bonnefoy, S.Bordas, P.Bregeon, J.Brun, F.Brun, P.Bryan, M.Büchele, M.Bulik, T.Bylund, T.Capasso, M.Caroff, S.Carosi, A.Casanova, S.Cerruti, M.Chakraborty, N.Chandra, S.Chaves, R.C.G.Chen, A.Cirelli, M.Colafrancesco, S.Condon, B.Davids, I.D.Deil, C.Devin, J.deWilt, P.Dirson, L.Djannati-Atai, A.Dmytriiev, A.Donath, A.Doroshenko, V.Drury, L.O'C.Dyks, J.Egberts, K.Emery, G.Ernenwein, J.-P.Eschbach, S.Fegan, S.Fiasson, A.Fontaine, G.Funk, S.Füßling, M.Gabici, S.Gallant, Y.A.Gaté, F.Giavitto, G.Glawion, D.Glicenstein, J.F.Gottschall, D.Grondin, M.-H.Hahn, J.Haupt, M.Heinzelmann, G.Henri, G.Hermann, G.Hinton, J.A.Hofmann, W.Hoischen, C.Holch, T.L.Holler, M.Horns, D.Huber, D.Iwasaki, H.Jacholkowska, A.Jamrozy, M.Jankowsky, D.Jankowsky, F.Jouvin, L.Jung-Richardt, I.Kastendieck, M.A.Katarzyński, K.Katsuragawa, M.Katz, U.Kerszberg, D.Khangulyan, D.Khélifi, B.King, J.Klepser, S.Kluźniak, W.Komin, Nu.Kosack, K.Krakau, S.Kraus, M.Krüger, P.P.Lamanna, G.Lau, J.Lefaucheur, J.Lemière, A.Lemoine-Goumard, M.Lenain, J.-P.Leser, E.Lohse, T.Lorentz, M.López-Coto, R.Lypova, I.Malyshev, D.Marandon, V.Marcowith, A.Mariaud, C.Martí-Devesa, G.Marx, R.Maurin, G.Meintjes, P.J.Mitchell, A.M.W.Moderski, R.Mohamed, M.Mohrmann, L.Moulin, E.Murach, T.Nakashima, S.de Naurois, M.Ndiyavala, H.Niederwanger, F.Niemiec, J.Oakes, L.O'Brien, P.Odaka, H.Ohm, S.Ostrowski, M.Oya, I.Padovani, M.Panci, P.Panter, M.Parsons, R.D.Perennes, C.Petrucci, P.-O.Peyaud, B.Piel, Q.Pita, S.Poireau, V.Priyana Noel, A.Prokhorov, D.A.Prokoph, H.Pühlhofer, G.Punch, M.Quirrenbach, A.Raab, S.Rauth, R.Reimer, A.Reimer, O.Renaud, M.Rieger, F.Rinchiuso, L.Romoli, C.Rowell, G.Rudak, B.Ruiz-Velasco, E.Sahakian, V.Saito, S.Sala, F.Sanchez, D.A.Santangelo, A.Sasaki, M.Schlickeiser, R.Schüssler, F.Schulz, A.Schwanke, U.Schwemmer, S.Seglar-Arroyo, M.Senniappan, M.Seyffert, A.S.Shafi, N.Shilon, I.Shiningayamwe, K.Silk, J.Simoni, R.Sinha, A.Sol, H.Spanier, F.Specovius, A.Spir-Jacob, M.Stawarz, L.Steenkamp, R.Stegmann, C.Steppa, C.Takahashi, T.Taoso, M.Tavernet, J.-P.Tavernier, T.Taylor, A.M.Terrier, R.Tibaldo, L.Tiziani, D.Tluczykont, M.Trichard, C.Tsirou, M.Tsuji, N.Tuffs, R.Uchiyama, Y.van der Walt, D.J.van Eldik, C.van Rensburg, C.van Soelen, B.Vasileiadis, G.Veh, J.Venter, C.Viana, A.Vincent, P.Vink, J.Voisin, F.Völk, H.J.Vuillaume, T.Wadiasingh, Z.Wagner, S.J.Wagner, R.M.White, R.Wierzcholska, A.Yang, R.Zaborov, D.Zacharias, M.Zanin, R.Zdziarski, A.A.Zech, A.Zefi, F.Ziegler, A.Zorn, J.Żywucka, N.Thu, 04 Oct 2018 02:50:49 GMT2018-10-01arXiv:1810.00995http://cds.cern.ch/record/2641652['arXiv:1810.00995']arXiv:1810.00995Higgs Criticality in a Viable Motivated Model
http://cds.cern.ch/record/2641476
An extension of the Standard Model with three right-handed neutrinos and a simple invisible axion model can account for all experimentally confirmed signals of new physics (neutrino oscillations, dark matter and baryon asymmetry) in addition to solving the strong CP problem, stabilizing the electroweak vacuum and satisfying all current observational bounds. We show that this model can also implement critical Higgs inflation, which corresponds to the frontier between stability and metastability of the electroweak vacuum. This leads to a value of the non-minimal coupling between the Higgs and the Ricci scalar that is much lower than the one usually quoted in Higgs inflation away from criticality. Then, an advantage is that the scale of perturbative unitarity breaking on flat spacetime can be very close to the Planck mass, where anyhow new physics is required. The higher dimensional operators are under control in this inflationary setup. The dependence of the cutoff on the Higgs background is also taken into account as appropriate when the Higgs is identified with the inflaton. Furthermore, critical Higgs inflation enjoys a robust inflationary attractor that makes it an appealing setup for the early universe. In the proposed model, unlike in the Standard Model, critical Higgs inflation can be realized without any tension with the observed quantities, such as the top mass and the strong coupling.Salvio, AlbertoWed, 03 Oct 2018 02:10:08 GMT2018-10-01arXiv:1810.00792http://cds.cern.ch/record/2641476['arXiv:1810.00792']arXiv:1810.00792Faint Light from Dark Matter: Classifying and Constraining Dark Matter-Photon Effective Operators
http://cds.cern.ch/record/2641475
Even if Dark Matter (DM) is neutral under electromagnetism, it can still interact with the Standard Model (SM) via photon exchange from higher-dimensional operators. Here we classify the general effective operators coupling DM to photons, distinguishing between Dirac/Majorana fermion and complex/real scalar DM. We provide model-independent constraints on these operators from direct and indirect detection. We also constrain various DM-lepton operators, which induce DM-photon interactions via RG running or which typically arise in sensible UV-completions. This provides a simple way to quickly assess constraints on any DM model that interacts mainly via photon exchange or couples to SM leptons.Kavanagh, Bradley J.Panci, PaoloZiegler, RobertWed, 03 Oct 2018 02:10:07 GMT2018-09-28arXiv:1810.00033http://cds.cern.ch/record/2641475['arXiv:1810.00033']arXiv:1810.00033Accurate simulation of W, Z and Higgs boson decays in Sherpa
http://cds.cern.ch/record/2640916
We discuss the inclusion of next-to-next-to leading order electromagnetic and of next-to leading order electroweak corrections to the leptonic decays of weak gauge and Higgs bosons in the SHERPA event generator. To this end, we modify the Yennie-Frautschi-Suura scheme for the resummation of soft photon corrections and its systematic improvement with fixed-order calculations, to also include the effect of virtual corrections due to the exchange of weak gauge bosons. We detail relevant technical aspects of our implementation and present numerical results for observables relevant for high-precision Drell-Yan and Higgs boson production and decay simulations at the LHC.Krauss, FrankLindert, Jonas M.Linten, RobinSchönherr, MarekSun, 30 Sep 2018 02:01:38 GMT2018-09-27arXiv:1809.10650http://cds.cern.ch/record/2640916['arXiv:1809.10650']arXiv:1809.10650TMD gluon distributions for multiparton processes
http://cds.cern.ch/record/2640319
We derive gauge invariant operators entering definitions of the Transverse Momentum Dependent (TMD) gluon distributions, for all five and six parton processes. Our calculations utilize color decomposition of amplitudes in the color flow basis. In addition, we find the general result for multi-gluon process (with arbitrary number of gluons) at large $N_{c}$. On phenomenological ground our results may be used for multi-jet production in the small-$x$ regime, where the TMD gluon distributions can be derived from the Color Glass Condensate effective theory.Bury, MarcinKotko, PiotrKutak, KrzysztofWed, 26 Sep 2018 02:03:31 GMT2018-09-24arXiv:1809.08968http://cds.cern.ch/record/2640319['arXiv:1809.08968']arXiv:1809.08968Detecting a Boosted Diboson Resonance
http://cds.cern.ch/record/2639898
New light scalar particles in the mass range of hundreds of GeV, decaying into a pair of $W/Z$ bosons can appear in several extensions of the SM. The focus of collider studies for such a scalar is often on its direct production, where the scalar is typically only mildly boosted. The observed $W/Z$ are therefore well-separated, allowing analyses for the scalar resonance in a standard fashion as a low-mass diboson resonance. In this work we instead focus on the scenario where the direct production of the scalar is suppressed, and it is rather produced via the decay of a significantly heavier (a few TeV mass) new particle, in conjunction with SM particles. Such a process results in the scalar being highly boosted, rendering the $W/Z$'s from its decay merged. The final state in such a decay is a "fat" jet, which can be either four-pronged (for fully hadronic $W/Z$ decays), or may be like a $W/Z$ jet, but with leptons buried inside (if one of the $W/Z$ decays leptonically). In addition, this fat jet has a jet mass that can be quite different from that of the $W/Z$/Higgs/top quark-induced jet, and may be missed by existing searches. In this work, we develop dedicated algorithms for tagging such multi-layered "boosted dibosons" at the LHC. As a concrete application, we discuss an extension of the standard warped extra-dimensional framework where such a light scalar can arise. We demonstrate that the use of these algorithms gives sensitivity in mass ranges that are otherwise poorly constrained.Agashe, KaustubhCollins, Jack H.Du, PeizhiHong, SungwooKim, DoojinMishra, Rashmish K.Sat, 22 Sep 2018 02:01:38 GMT2018-09-19arXiv:1809.07334http://cds.cern.ch/record/2639898['arXiv:1809.07334']arXiv:1809.07334Relativistic entanglement of two particles driven by continuous product momenta
http://cds.cern.ch/record/2639264
In this paper we explore the entanglement of two relativistic spin-$1/2$
particles with continuous momenta. The spin state is described by the Bell
state and the momenta are given by Gaussian distributions of product form.
Transformations of the spins are systematically investigated in different boost
scenarios by calculating the orbits and concurrence of the spin degree of
freedom. By visualizing the behavior of the spin state we get further insight
into how and why the entanglement changes in different boost situations.Palge, VeikoDunningham, JacobGroote, StefanLiivat, HannesVeermäe, HardiThu, 20 Sep 2018 02:24:33 GMT2014-09-03arXiv:1409.1316http://cds.cern.ch/record/2639264['arXiv:1409.1316']arXiv:1409.1316Strongly Coupled Quintessence
http://cds.cern.ch/record/2639261
We present a family of consistent quantum field theories of monodromy quintessence in strong coupling, which can serve as benchmarks in modeling dark energy different from cosmological constant. These theories have discrete gauge symmetries which can protect them from quantum field theory and quantum gravity corrections, both perturbative and nonperturbative. The strong coupling effects, at scales $\ga {\rm mm}^{-1}$, flatten the potential and activate operators with higher powers of derivatives. The predicted equation of state is close to, but not exactly equal to $-1$, thus being within reach of the (near!) future programs to explore the nature of dark energy.D'Amico, GuidoKaloper, NemanjaLawrence, AlbionThu, 20 Sep 2018 02:24:17 GMT2018-09-13arXiv:1809.05109http://cds.cern.ch/record/2639261['arXiv:1809.05109']arXiv:1809.05109Two-loop massless QCD corrections to the $g+g \rightarrow H+H$ four-point amplitude
http://cds.cern.ch/record/2639260
We compute the two-loop massless QCD corrections to the four-point amplitude $g+g \rightarrow H+H$ resulting from effective operator insertions that describe the interaction of a Higgs boson with gluons in the infinite top quark mass limit. This amplitude is an essential ingredient to the third-order QCD corrections to Higgs boson pair production. We have implemented our results in a numerical code that can be used for further phenomenological studies.Banerjee, PulakBorowka, SophiaDhani, Prasanna K.Gehrmann, ThomasRavindran, V.Thu, 20 Sep 2018 02:24:15 GMT2018-09-14arXiv:1809.05388http://cds.cern.ch/record/2639260['arXiv:1809.05388']arXiv:1809.05388Double-real contribution to the quark beam function at N$^{3}$LO QCD
http://cds.cern.ch/record/2639259
We compute the master integrals required for the calculation of the double-real emission contributions to the matching coefficients of jettiness beam functions at next-to-next-to-next-to-leading order in perturbative QCD. As an application, we combine these integrals and derive the double-real emission contribution to the matching coefficient $I_{qq}(t,z)$ of the quark beam function.Melnikov, KirillRietkerk, RobbertTancredi, LorenzoWever, ChristopherThu, 20 Sep 2018 02:24:13 GMT2018-09-17arXiv:1809.06300http://cds.cern.ch/record/2639259['arXiv:1809.06300']arXiv:1809.06300Sampling the Riemann-Theta Boltzmann Machine
http://cds.cern.ch/record/2639022
We show that the visible sector probability density function of the Riemann-Theta Boltzmann machine corresponds to a gaussian mixture model consisting of an infinite number of component multi-variate gaussians. The weights of the mixture are given by a discrete multi-variate gaussian over the hidden state space. This allows us to sample the visible sector density function in a straight-forward manner. Furthermore, we show that the visible sector probability density function possesses an affine transform property, similar to the multi-variate gaussian density.Carrazza, StefanoKrefl, DanielWed, 19 Sep 2018 04:08:20 GMT2018-04-20CERN-TH-2018-085http://cds.cern.ch/record/26390222018085Updated fits to the present $b \to s \ell ^+\ell ^-$ data
http://cds.cern.ch/record/2639020
We discuss the observed deviations in b → s`+` − processes from the Standard Model predictions and present global fits for both hadronic effects and the new physics description of these anomalies. We investigate whether the different anomalies can be described by a consistent new physics effect. We consider all the possible relevant new physics contributions to the semileptonic b → s transitions. Moreover, we study the prospects of future LHCb upgrade for establishing new physics with the theoretically clean observables.Mahmoudi, FHurth, TNeshatpour, SWed, 19 Sep 2018 04:08:18 GMThttp://cds.cern.ch/record/2639020['']Updating the MACHO fraction of the Milky Way dark halo with improved mass models
http://cds.cern.ch/record/2639019
Recent interest in primordial black holes as a possible dark matter candidate has motivated the reanalysis of previous methods for constraining massive astrophysical compact objects in the Milky Way halo and beyond. In order to derive these constraints, a model for the dark matter distribution around the Milky Way must be used. Previous microlensing searches have assumed a semi-isothermal density sphere for this task. We show this model is no longer consistent with data from the Milky Way rotation curve, and test two replacement models, namely NFW and power-law. The power-law model is the most flexible as it can break spherical symmetry, and best fits the data. Thus, we recommend the power-law model as a replacement, although it still lacks the flexibility to fully encapsulate all possible shapes of the Milky Way halo. We then use the power-law model to rederive some previous microlensing constraints in the literature, while propagating the primary halo-shape uncertainties through to our final constraints. Our analysis reveals that the microlensing constraints towards the Large Magellanic Cloud weaken somewhat for MACHO masses around $10\, M_\odot$ when this uncertainty is taken into account, but the constraints tighten at lower masses. Exploring some of the simplifying assumptions of previous constraints we also study the effect of wide mass distributions of compact halo objects, as well as the effect of spatial clustering on microlensing constraints. We find that both effects induce a shift in the constraints towards smaller masses, and can effectively remove the microlensing constraints from $M \sim 1-10 M_\odot$ for certain MACHO populations.Calcino, JoshGarcia-Bellido, JuanDavis, Tamara M.Wed, 19 Sep 2018 04:08:15 GMT2018-03-25arXiv:1803.09205http://cds.cern.ch/record/2639019['arXiv:1803.09205']arXiv:1803.09205Gauge invariance for a class of tree diagrams in the standard model
http://cds.cern.ch/record/2638832
For gauge theory, the matrix element for any physical process is independent of the gauge used. Since this is a formal statement and examples are known where gauge invariance is violated, for any speciﬁc process this gauge invariance needs to be checked by explicit calculation. In this paper, gauge invariance is found to hold for a large non-trivial class of processes described by tree diagrams in the standard model-tree diagrams with two external $W$ bosons and any number of external Higgs bosons. This veriﬁcation of gauge invariance is quite complicated, and is based on a direct study of the difference between different gauges through induction on the number of external Higgs bosons.Wu, Tai TsunWu, Sau LanTue, 18 Sep 2018 07:36:29 GMThttp://cds.cern.ch/record/2638832['']Calculation of the Z+jet cross section including transverse momenta of initial partons
http://cds.cern.ch/record/2638492
We perform calculations of Z+jet cross-section taking into account the transverse momenta of the initial partons. Transverse Momentum Dependent (TMD) parton densities obtained with the Parton Branching method are used and higher order corrections are included via TMD parton showers in the initial state. The predictions are compared to measurements of forward Z+jet production of the LHCb collaboration at $\sqrt{s}=7$ TeV. We show that the results obtained in $k_T$-factorization are in good agreement with results obtained from a NLO calculation matched with traditional parton showers. We also demonstrate that in the forward rapidity region, $k_T$-factorization and hybrid factorization predictions agree with each other.Deak, M.van Hameren, A.Jung, H.Kusina, A.Kutak, K.Serino, M.Sat, 15 Sep 2018 02:46:17 GMT2018-09-11arXiv:1809.03854http://cds.cern.ch/record/2638492['arXiv:1809.03854']arXiv:1809.03854