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Physics Opportunities of a 100 TeV Proton-Proton Collider
http://cds.cern.ch/record/2104388
The discovery of the Higgs boson at the LHC exposes some of the most profound mysteries fundamental physics has encountered in decades, opening the door to the next phase of experimental exploration. More than ever, this will necessitate new machines to push us deeper into the energy frontier. In this article, we discuss the physics motivation and present the physics potential of a proton-proton collider running at an energy significantly beyond that of the LHC and a luminosity comparable to that of the LHC. 100 TeV is used as a benchmark of the center of mass energy, with integrated luminosities from 3 inverse ab to 30 inverse ab.Arkani-Hamed, NimaHan, TaoMangano, MichelangeloWang, Lian-TaoMon, 23 Nov 2015 06:45:42 GMT20 Nov 2015arXiv:1511.06495http://cds.cern.ch/record/2104388['arXiv:1511.06495']arXiv:1511.06495Supersymmetry Searches in GUT Models with Non-Universal Scalar Masses
http://cds.cern.ch/record/2104139
We study SO(10), SU(5) and flipped SU(5) GUT models with non-universal soft supersymmetry-breaking scalar masses, exploring how they are constrained by LHC supersymmetry searches and cold dark matter experiments, and how they can be probed and distinguished in future experiments. We find characteristic differences between the various GUT scenarios, particularly in the coannihilation region, which is very sensitive to changes of parameters. For example, the flipped SU(5) GUT predict the possibility of $\tilde{t}_1-\chi$ coannihilation, which is absent in the regions of the SO(10) and SU(5) GUT parameter spaces that we study. We use the relic density predictions in different models to determine upper bounds for the neutralino masses, and we find large differences between different GUT models in the sparticle spectra for the same LSP mass, leading to direct connections of distinctive possible experimental measurements with the structure of the GUT group. We find that future LHC searches for generic missing $E_T$, charginos and stops will be able to constrain the different GUT models in complementary ways, as will the Xenon 1 ton and Darwin dark matter scattering experiments and future FERMI or CTA $\gamma$-ray searches.Cannoni, MEllis, JGómez, M ELola, Sde Austri, R RuizFri, 20 Nov 2015 06:35:58 GMT19 Nov 2015arXiv:1511.06205http://cds.cern.ch/record/2104139['arXiv:1511.06205']arXiv:1511.06205A status update on the determination of ${\Lambda}_{\overline{\rm MS}}^{N_{\rm f}=3}$ by the ALPHA collaboration
http://cds.cern.ch/record/2103860
The ALPHA collaboration aims to determine $\alpha_s(m_Z)$ with a total error below the percent level. A further step towards this goal can be taken by combining results from the recent simulations of 2+1-flavour QCD by the CLS initiative with a number of tools developed over the years: renormalized couplings in finite volume schemes, recursive finite size techniques, two-loop renormalized perturbation theory and the (improved) gradient flow on the lattice. We sketch the strategy, which involves both the standard SF coupling in the high energy regime and a gradient flow coupling at low energies. This implies the need for matching both schemes at an intermediate switching scale, $L_{\rm swi}$, which we choose roughly in the range 2-4 GeV. In this contribution we present a preliminary result for this matching procedure, and we then focus on our almost final results for the scale evolution of the SF coupling from $L_{\rm swi}$ towards the perturbative regime, where we extract the $N_{\rm f} = 3$ ${\Lambda}$-parameter, ${\Lambda}_{\overline{\rm MS}}^{N_{\rm f}=3}$, in units of $L_{\rm swi}$ . Connecting $L_{\rm swi}$ and thus the ${\Lambda}$-parameter to a hadronic scale such as $F_K$ requires 2 further ingredients: first, the connection of $L_{\rm swi}$ to $L_{\rm max}$ using a few steps with the step-scaling function of the gradient flow coupling, and, second, the continuum extrapolation of $L_{\rm max} F_K$.Brida, Mattia DallaFritzsch, PatrickKorzec, TomaszRamos, AlbertoSint, StefanSommer, RainerThu, 19 Nov 2015 07:35:26 GMT18 Nov 2015arXiv:1511.05831http://cds.cern.ch/record/2103860['arXiv:1511.05831']arXiv:1511.05831Gauging MSSM global symmetries and SUSY breaking in de Sitter vacuum
http://cds.cern.ch/record/2102286
We elaborate on a recent study of a model of supersymmetry breaking we proposed recently, in the presence of a tunable positive cosmological constant, based on a gauged shift symmetry of a string modulus, external to the Standard Model (SM) sector. Here, we identify this symmetry with a global symmetry of the SM and work out the corresponding phenomenology. A particularly attracting possibility is to use a combination of Baryon and Lepton number that contains the known matter parity and guarantees absence of dimension-four and five operators that violate B and L.Antoniadis, IgnatiosKnoops, RobMon, 16 Nov 2015 06:29:05 GMT13 Nov 2015arXiv:1511.04283http://cds.cern.ch/record/2102286['arXiv:1511.04283']arXiv:1511.04283Effects of higher dimension operators on the Standard Model Higgs sector
http://cds.cern.ch/record/2093351
We study the effect of higher dimension operators on the electroweak finite temperature phase transition in two sectors of the Standard Model. Firstly, the Higgs-Yukawa sector, consisting of the Higgs doublet and the massive Standard Model fermions, is studied with an approximate method, Extended Mean Field Theory. Secondly, the gauge-Higgs sector, consisting of the Higgs doublet and the gauge fields of the weak interaction, is studied using Monte Carlo simulations. In both cases we find that a cutoff scale of around 1.5 TeV is needed to make the electroweak phase transition first order at the experimental value of the Higgs boson mass, which is a requirement for making electroweak baryogenesis viable.Akerlund, Oscarde Forcrand, PhilippeSteinbauer, JakobFri, 13 Nov 2015 07:12:55 GMT12 Nov 2015arXiv:1511.03867http://cds.cern.ch/record/2093351['arXiv:1511.03867']arXiv:1511.03867New Physics in $B$ decays
http://cds.cern.ch/record/2093340
While the LHC did not observe direct evidence for physics beyond the standard model, indirect hints for new physics were uncovered in the flavour sector in the decays $B\to K^*\mu^+\mu^-$, $B\to K\mu^+\mu^-/B\to Ke^+e^-$, $B_s\to\phi\mu^+\mu^-$, $B\to D^{(*)}\tau\nu$ and $h\to\tau^\pm\mu^\mp$. Each observable deviates from the SM predictions at the $2-3\,\sigma$ level only, but combining all $b\to s\mu^+\mu^-$ data via a global fit, one finds $4-5\,\sigma$ difference for NP compared to the SM and combining $B\to D^{*}\tau\nu$ with $B\to D\tau\nu$ one obtains $3.9\,\sigma$. While $B\to D^{(*)}\tau\nu$ and $h\to\tau\mu$ can be naturally explained by an extended Higgs sector, the $b\to s\mu^+\mu^-$ anomalies point at a $Z'$ gauge boson. However, it is also possible to explain $B\to D^{(*)}\tau\nu$ and $b\to s\mu^+\mu^-$ simultaneously with leptoquarks while their effect in $h\to\tau^\pm\mu^\mp$ is far too small to account for current data. Combining a 2HDM with a gauged $L_\mu-L_\tau$ symmetry allows for explaining the $b\to s\mu^+\mu^-$ anomalies in combination with $h\to\tau^\pm\mu^\mp$, predicting interesting correlations with $\tau\to3\mu$. In the light of these deviations from the SM we also discuss the possibilities of observing lepton flavour violating $B$ decays (e.g. $B\to K^{(*)}\tau^\pm\mu^\mp$ and $B_s\to\tau^\pm\mu^\mp$).Crivellin, AndreasFri, 13 Nov 2015 07:11:12 GMT12 Nov 2015arXiv:1511.04015http://cds.cern.ch/record/2093340['arXiv:1511.04015']arXiv:1511.04015Theta series, wall-crossing and quantum dilogarithm identities
http://cds.cern.ch/record/2066877
Motivated by mathematical structures which arise in string vacua and gauge theories with N=2 supersymmetry, we study the properties of certain generalized theta series which appear as Fourier coefficients of functions on a twisted torus. In Calabi-Yau string vacua, such theta series encode instanton corrections from $k$ Neveu-Schwarz five-branes. The theta series are determined by vector-valued wave-functions, and in this work we obtain the transformation of these wave-functions induced by Kontsevich-Soibelman symplectomorphisms. This effectively provides a quantum version of these transformations, where the quantization parameter is inversely proportional to the five-brane charge $k$. Consistency with wall-crossing implies a new five-term relation for Faddeev's quantum dilogarithm $\Phi_b$ at $b=1$, which we prove. By allowing the torus to be non-commutative, we obtain a more general five-term relation valid for arbitrary $b$ and $k$, which may be relevant for the physics of five-branes at finite chemical potential for angular momentum.Alexandrov, SergeiPioline, BorisWed, 11 Nov 2015 09:22:29 GMT09 Nov 2015arXiv:1511.02892http://cds.cern.ch/record/2066877['arXiv:1511.02892']arXiv:1511.02892$\mathcal{N}=2^\star$ from Topological Amplitudes in String Theory
http://cds.cern.ch/record/2066876
In this paper, we explicitly construct string theory backgrounds that realise the so-called $\mathcal N=2^\star$ gauge theory. We prove the consistency of our models by calculating their partition function and obtaining the correct gauge theory spectrum. We further provide arguments in favour of the universality of our construction which covers a wide class of models all of which engineer the same gauge theory. We reproduce the corresponding Nekrasov partition function once the $\Omega$-deformation is included and the appropriate field theory limit taken. This is achieved by calculating the topological amplitudes $F_g$ in the string models. In addition to heterotic and type II constructions, we also realise the mass deformation in type I theory, thus leading to a natural way of uplifting the result to the instanton sector.Florakis, IoannisAssi, Ahmad ZeinWed, 11 Nov 2015 09:22:29 GMT09 Nov 2015arXiv:1511.02887http://cds.cern.ch/record/2066876['arXiv:1511.02887']arXiv:1511.02887Jet-vetoed Higgs cross section in gluon fusion at N3LO+NNLL with small-R resummation
http://cds.cern.ch/record/2066849
We present new results for the jet-veto efficiency and zero-jet cross section in Higgs production through gluon fusion. We incorporate the N$^3$LO corrections to the total cross section, the NNLO corrections to the 1-jet rate, NNLL resummation for the jet $p_t$ and LL resummation for the jet radius dependence. Our results include known finite-mass corrections and are obtained using the jet-veto efficiency method, updated relative to earlier work to take into account what has been learnt from the new precision calculations that we include. For 13 TeV collisions and using our default choice for the renormalisation and factorisation scales, $\mu_0=m_H/2$, the matched prediction for the jet-veto efficiency increases the pure NNNLO prediction by about 2% and the two have comparable uncertainties. Relative to NNLO+NNLL results, the new prediction is 2% smaller and the uncertainty reduces from more than 10% to less than 5%. Results are also presented for the central scale $\mu_0=m_H$.Banfi, AndreaCaola, FabrizioDreyer, Frédéric AMonni, Pier FSalam, Gavin PZanderighi, GiuliaDulat, FalkoWed, 11 Nov 2015 09:20:16 GMT09 Nov 2015arXiv:1511.02886http://cds.cern.ch/record/2066849['arXiv:1511.02886']arXiv:1511.02886Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale
http://cds.cern.ch/record/2065389
Colferai, DimitriVeneziano, GabrieleCiafaloni, MarcelloMon, 09 Nov 2015 07:49:28 GMThttp://cds.cern.ch/record/2065389['']Spontaneously Broken Yang-Mills-Einstein Supergravities as Double Copies
http://cds.cern.ch/record/2065327
Color/kinematics duality and the double-copy construction have proved to be systematic tools for gaining new insight into gravitational theories. Extending our earlier work, in this paper we introduce new double-copy constructions for large classes of spontaneously-broken Yang-Mills-Einstein theories with adjoint Higgs fields. One gauge-theory copy entering the construction is a spontaneously-broken (super-)Yang-Mills theory, while the other copy is a bosonic Yang-Mills-scalar theory with trilinear scalar interactions that display an explicitly-broken global symmetry. We show that the kinematic numerators of these gauge theories can be made to obey color/kinematics duality by exhibiting particular additional Lie-algebraic relations. We discuss in detail explicit examples with N=2 supersymmetry, focusing on Yang-Mills-Einstein supergravity theories belonging to the generic Jordan family in four and five dimensions, and identify the map between the supergravity and double-copy fields and parameters. We also briefly discuss the application of our results to N=4 supergravity theories. The constructions are illustrated by explicit examples of tree-level and one-loop scattering amplitudes.Chiodaroli, MarcoGunaydin, MuratJohansson, HenrikRoiban, RaduSat, 07 Nov 2015 11:19:33 GMT05 Nov 2015arXiv:1511.01740http://cds.cern.ch/record/2065327['arXiv:1511.01740']arXiv:1511.01740Information Retention by Stringy Black Holes
http://cds.cern.ch/record/2065292
Building upon our previous work on two-dimensional stringy black holes and its extension to spherically-symmetric four-dimensional stringy black holes, we show how the latter retain information. A key r\^ole is played by an infinite-dimensional $W_\infty$ symmetry that preserves the area of an isolated black-hole horizon and hence its entropy. The exactly-marginal conformal world-sheet operator representing a massless stringy particle interacting with the black hole necessarily includes a contribution from $W_\infty$ generators in its vertex function. This admixture manifests the transfer of information between the string black hole and external particles. We discuss different manifestations of $W_\infty$ symmetry in black-hole physics and the connections between them.Ellis, JohnMavromatos, Nick ENanopoulos, D VSat, 07 Nov 2015 11:18:03 GMT05 Nov 2015arXiv:1511.01825http://cds.cern.ch/record/2065292['arXiv:1511.01825']arXiv:1511.01825A study of multi-jet production in association with an electroweak vector boson
http://cds.cern.ch/record/2064914
We consider the production of a single $Z$ or $W$ boson in association with jets at the LHC. We compute the corresponding cross sections by matching NLO QCD predictions with the Herwig++ and Pythia8 parton showers, and by merging all of the underlying matrix elements with up to two light partons at the Born level. We compare our results with several 7-TeV measurements by the ATLAS and CMS collaborations, and overall we find a good agreement between theory and data.Frederix, RikkertFrixione, StefanoPapaefstathiou, AndreasPrestel, StefanTorrielli, PaoloThu, 05 Nov 2015 07:05:11 GMT03 Nov 2015arXiv:1511.00847http://cds.cern.ch/record/2064914['arXiv:1511.00847']arXiv:1511.00847A Geometric Formulation of Higgs Effective Field Theory: Measuring the Curvature of Scalar Field Space
http://cds.cern.ch/record/2064909
A geometric formulation of Higgs Effective Field Theory (HEFT) is presented. Experimental observables are given in terms of geometric invariants of the scalar sigma model sector such as the curvature of the scalar field manifold $\mathcal M$. We show how the curvature can be measured experimentally via Higgs cross-sections, $W_L$ scattering, and the $S$ parameter. The one-loop action of HEFT is given in terms of geometric invariants of $\mathcal M$. The distinction between the Standard Model (SM) and HEFT is whether $\mathcal M$ is flat or curved, not whether the scalars transform linearly or non-linearly under the electroweak group.Alonso, RodrigoJenkins, Elizabeth EManohar, Aneesh VThu, 05 Nov 2015 07:05:09 GMT02 Nov 2015arXiv:1511.00724http://cds.cern.ch/record/2064909['arXiv:1511.00724']arXiv:1511.00724Di-boson Production beyond NLO QCD and Anomalous Couplings
http://cds.cern.ch/record/2064889
In these proceedings, we review results for several di-boson production processes beyond NLO QCD at high transverse momenta using the VBFNLO Monte-Carlo program together with the LOOPSIM method. Additionally, we show for the WZ production process how higher order QCD corrections can resemble anomalous coupling effects.Campanario, FRauch, MRoth, RSapeta, SZeppenfeld, DThu, 05 Nov 2015 07:02:36 GMT03 Nov 2015arXiv:1511.00913http://cds.cern.ch/record/2064889['arXiv:1511.00913']arXiv:1511.00913Hypermagnetic gyrotropy, inflation and the baryon asymmetry of the Universe
http://cds.cern.ch/record/2064131
We investigate the production of the hypermagnetic gyrotropy when the electric and magnetic gauge couplings evolve at different rates, as it happens in the the relativistic theory of the Van der Waals forces. If a pseudo-scalar interaction breaks the duality symmetry of the corresponding equations, the gyrotropic configurations of the hypermagnetic fields can be amplified from the vacuum during an inflationary stage of expansion. After charting the parameter space of the model in terms of the rates of evolution of the magnetic and electric gauge couplings, we identify the regions where the gyrotropy is sufficiently intense to seed the baryon asymmetry of the Universe at the electroweak epoch while the backreaction constraints, the strong coupling bounds and the other astrophysical limits are concurrently satisfied.Giovannini, MassimoTue, 03 Nov 2015 06:40:39 GMT31 Oct 2015arXiv:1511.00138http://cds.cern.ch/record/2064131['arXiv:1511.00138']arXiv:1511.00138Resummation ambiguities in the Higgs transverse-momentum spectrum in the Standard Model and beyond
http://cds.cern.ch/record/2063845
We study the prediction for the Higgs transverse momentum distribution in gluon fusion and focus on the problem of matching fixed- and all-order perturbative results. The main sources of matching ambiguities on this distribution are investigated by means of a twofold comparison. On the one hand, we present a detailed qualitative and quantitative comparison of two recently introduced algorithms for determining the matching scale. On the other hand, we apply the results of both methods to three widely used approaches for the resummation of logarithmically enhanced contributions at small transverse momenta: the MC@NLO and POWHEG Monte Carlo approaches, and analytic resummation. While the three sets of results are largely compatible in the low-pT region, they exhibit sizable differences at large pT. We show that these differences can be significantly reduced by suitable modifications of formally subleading terms in the Monte Carlo implementations. We apply our study to the Standard Model Higgs boson and to the neutral Higgs bosons of the Two-Higgs-Doublet Model for representative scenarios of the parameter space, where the top- and bottom-quark diagrams enter the cross section at different strength.Bagnaschi, EmanueleHarlander, Robert VMantler, HendrikVicini, AlessandroWiesemann, MariusMon, 02 Nov 2015 06:45:21 GMT29 Oct 2015arXiv:1510.08850http://cds.cern.ch/record/2063845['arXiv:1510.08850']arXiv:1510.08850Remarks on the Convergence Properties of the Conformal Block Expansion
http://cds.cern.ch/record/2063607
We show how to refine conformal block expansion convergence estimates from hep-th/1208.6449. In doing so we find a novel explicit formula for the 3d conformal blocks on the real axis.Rychkov, SlavaYvernay, PierreFri, 30 Oct 2015 06:40:15 GMT28 Oct 2015arXiv:1510.08486http://cds.cern.ch/record/2063607['arXiv:1510.08486']arXiv:1510.08486Lepton Flavor and Non-Universality from Minimal Composite Higgs Setups
http://cds.cern.ch/record/2063238
We present a new class of models of lepton flavor in the composite Higgs framework. Following the concept of minimality, they lead to a rich phenomenology in good agreement with the current experimental picture. Due to a unification of the right-handed leptons, our scenario is very predictive and can naturally lead to a violation of lepton-flavor universality in neutral current interactions. We will show that in particular the anomaly in $R_K= {\cal B}(B \to K \mu^+ \mu^-)/{\cal B}(B \to K e^+ e^-)$, found by LHCb, can be addressed, while other constraints from quark- and lepton-flavor physics are met. In fact, the minimal structure of the setup allows for the implementation of a very powerful flavor protection, which avoids the appearance of new sources of flavor-changing neutral currents to very good approximation. Finally, the new lepton sector provides a parametrically enhanced correction to the Higgs mass, such that the need for ultra-light top partners is weakened considerably, linking the mass of the latter with the size of the neutrino masses.Carmona, AdrianGoertz, FlorianThu, 29 Oct 2015 07:41:13 GMT26 Oct 2015arXiv:1510.07658http://cds.cern.ch/record/2063238['arXiv:1510.07658']arXiv:1510.07658(Dimensional) twisted reduction in large N gauge theories
http://cds.cern.ch/record/2063233
We show that the spontaneous breaking of center symmetry can be avoided on a $L^2\times 1^2$ lattice with the appropriate choice of twisted boundary conditions. In order for this to work it is crucial that the twisted boundary conditions are chosen in the reduced plane. This suggests that the choice of twist tensor can influence the directions in which color and space degrees of freedom become indistinguishable. We also present some preliminary quantitative data comparing the value of the plaquette for different forms of reduction.Keegan, LiamRamos, AlbertoThu, 29 Oct 2015 07:40:48 GMT28 Oct 2015arXiv:1510.08360http://cds.cern.ch/record/2063233['arXiv:1510.08360']arXiv:1510.08360Prospects for Supersymmetry at the LHC & Beyond
http://cds.cern.ch/record/2061799
Run 1 of the LHC has provided three new motivations for supersymmetry: the need to stabilize the electroweak vacuum, the mass of the Higgs boson, and the fact that its couplings are Standard Model-like (so far). The prospects for discovering (and measuring) supersymmetry during future runs of the LHC are discussed in the frameworks of the constrained MSSM (CMSSM), models with non-universal soft supersymmetry-breaking contributions to Higgs masses (NUHM1,2) and the phenomenological MSSM with 10 arbitrary soft supersymmetry-breaking parameters (pMSSM10). In addition to the classic searches for missing transverse energy, searches for long-lived charged sparticles may also be promising. If supersymmetry does show up at the LHC, there are good prospects for measurements of the spectrum that can be compared with the indirect indications from other experiments. On the other hand, a higher-energy future circular proton-proton collider may be the best option for discovering supersymmetry if it does not appear at the LHC.Ellis, JohnFri, 23 Oct 2015 06:50:45 GMT21 Oct 2015arXiv:1510.06204http://cds.cern.ch/record/2061799['arXiv:1510.06204']arXiv:1510.06204The Arithmetic of Elliptic Fibrations in Gauge Theories on a Circle
http://cds.cern.ch/record/2059977
The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional Coulomb branch. Its existence is required by consistency with Higgs transitions from the non-Abelian theory to its Abelian phases in which it becomes the Mordell-Weil group. This hints towards the existence of a new underlying geometric symmetry.Grimm, Thomas WKapfer, AndreasKlevers, DenisFri, 16 Oct 2015 05:33:33 GMT14 Oct 2015arXiv:1510.04281http://cds.cern.ch/record/2059977['arXiv:1510.04281']arXiv:1510.04281Sensitivities of Prospective Future e+e- Colliders to Decoupled New Physics
http://cds.cern.ch/record/2059947
We explore the indirect sensitivities to decoupled new physics of prospective precision electroweak measurements, triple-gauge-coupling measurements and Higgs physics at future $e^+e^-$ colliders, with emphasis on the ILC250 and FCC-ee. The Standard Model effective field theory (SM EFT) is adopted as a model-independent approach for relating experimental precision projections to the scale of new physics, and we present prospective constraints on the Wilson coefficients of dimension-6 operators. We find that in a marginalised fit ILC250 EWPT measurements may be sensitive to new physics scales $\Lambda = \mathcal{O}(10)$~TeV, and FCC-ee EWPT measurements may be sensitive to $\Lambda = \mathcal{O}(30)$~TeV. The prospective sensitivities of Higgs and TGC measurements at the ILC250 (FCC-ee) are to $\Lambda = \mathcal{O}(1)$~TeV ($\Lambda = \mathcal{O}(2)$~TeV).Ellis, JohnYou, TevongFri, 16 Oct 2015 05:32:23 GMT15 Oct 2015arXiv:1510.04561http://cds.cern.ch/record/2059947['arXiv:1510.04561']arXiv:1510.04561Double-Copy Constructions and Unitarity Cuts
http://cds.cern.ch/record/2059646
The duality between color and kinematics enables the construction of multiloop gravity integrands directly from corresponding gauge-theory integrands. This has led to new nontrivial insights into the structure of gravity theories, including the discovery of enhanced ultraviolet cancellations. To continue to gain deeper understandings and probe these new properties, it is crucial to further improve techniques for constructing multiloop gravity integrands. In this paper, we show by example how one can alleviate difficulties encountered at the multiloop level by relaxing the color-kinematics duality conditions to hold manifestly only on unitarity cuts instead of globally on loop integrands. As an example, we use a minimal ansatz to construct an integrand for the two-loop four-point nonsupersymmetric pure Yang-Mills amplitude in $D$ dimensions that is compatible with these relaxed color-kinematics duality constraints. We then immediately obtain a corresponding gravity integrand through the double-copy procedure. Comments on ultraviolet divergences are also included.Bern, ZviDavies, ScottNohle, JoshThu, 15 Oct 2015 08:04:53 GMT12 Oct 2015arXiv:1510.03448http://cds.cern.ch/record/2059646['arXiv:1510.03448']arXiv:1510.03448Scenarios for Gluino Coannihilation
http://cds.cern.ch/record/2059585
We study supersymmetric scenarios in which the gluino is the next-to-lightest supersymmetric particle (NLSP), with a mass sufficiently close to that of the lightest supersymmetric particle (LSP) that gluino coannihilation becomes important. One of these scenarios is the MSSM with soft supersymmetry-breaking squark and slepton masses that are universal at an input GUT renormalization scale, but with non-universal gaugino masses. The other scenario is an extension of the MSSM to include vector-like supermultiplets. In both scenarios, we identify the regions of parameter space where gluino coannihilation is important, and discuss their relations to other regions of parameter space where other mechanisms bring the dark matter density into the range allowed by cosmology. In the case of the non-universal MSSM scenario, we find that the allowed range of parameter space is constrained by the requirement of electroweak symmetry breaking, the avoidance of a charged LSP and the measured mass of the Higgs boson, in particular, as well as the appearance of other dark matter (co)annihilation processes. Nevertheless, LSP masses $m_\chi \lesssim 8$~TeV with the correct dark matter density are quite possible. In the case of pure gravity mediation with additional vector-like supermultiplets, changes to the anomaly-mediated gluino mass and the threshold effects associated with these states can make the gluino almost degenerate with the LSP, and we find a similar upper bound.Ellis, JohnEvans, Jason LLuo, FengOlive, Keith AThu, 15 Oct 2015 06:17:57 GMT12 Oct 2015arXiv:1510.03498http://cds.cern.ch/record/2059585['arXiv:1510.03498']arXiv:1510.03498