We review and explain an infinite-dimensional counterpart of the Hurwitz theory realization (Alexeevski and Natanzon, Math. Russ. Izv. 72:3-24, 2008) of algebraic open-closed-string model à la Moore and Lazaroiu, where the closed and open sectors are represented by conjugation classes of permutations and the pairs of permutations, i.e. by the algebra of Young diagrams and bipartite graphs, respectively. An intriguing feature of this Hurwitz string model is the coexistence of two different multiplications, reflecting the deep interrelation between the theory of symmetric and linear groups, S∞ and GL(∞).
A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2TeVTeV. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8TeVTeV corresponding to an integrated luminosity of 19.7fb−1fb−1. The dijet azimuthal decorrelation is caused by the radiation of additional jets and probes the dynamics of multijet production. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. Event generators with only two outgoing high transverse momentum partons fail to describe the measurement, even when supplemented with next-to-leading-order QCD corrections and parton showers. Much better agreement is achieved when at least three outgoing partons are complemented through either next-to-leading-order predictions or parton showers. This observation emphasizes the need to improve predictions for multijet production.
The differential cross section and charge asymmetry for inclusive pp→W±+X→μ±ν+Xpp→W±+X→μ±ν+Xproduction at s√=8TeVs=8TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8fb−1fb−1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10−310−3 to 10−110−1.
A remarkable feature of Schur functions—the common eigenfunctions of cut-and-join operators from W∞W∞—is that they factorize at the peculiar two-parametric topological locus in the space of time variables, which is known as the hook formula for quantum dimensions of representations of Uq(SLN)Uq(SLN) and which plays a big role in various applications. This factorization survives at the level of Macdonald polynomials. We look for its further generalization to generalized Macdonald polynomials (GMPs), associated in the same way with the toroidal Ding–Iohara–Miki algebras, which play the central role in modern studies in Seiberg-Witten–Nekrasov theory. In the simplest case of the first-coproduct eigenfunctions, where GMP depend on just two sets of time variables, we discover a weak factorization—on a one- (rather than four-) parametric slice of the topological locus, which is already a very non-trivial property, calling for proof and better understanding.
Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9fb-1fb-1 of proton-proton collisions at a centre-of-mass energy of 8TeVTeVproduced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either through a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755GeVGeV in the case of neutralino masses below 200GeVGeV. For decays via a chargino, top squark masses up to 620GeVGeV are excluded, depending on the masses of the chargino and neutralino.
A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (HH) in proton-proton collisions collected by the CMS experiment at the LHC at s√=8TeVs=8TeV. The data correspond to an integrated luminosity of 19.7fb−1fb−1. The search considers HHHH resonances with masses between 1 and 3TeVTeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and tt¯tt¯ events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 % confidence level for the product of the production cross section and branching fraction σ(gg→X)B(X→HH→bb¯¯¯bb¯¯¯)σ(gg→X)B(X→HH→bb¯bb¯) range from 10 to 1.5\,fb\,fb for the mass of X from 1.15 to 2.0TeVTeV, significantly extending previous searches. For a warped extra dimension theory with a mass scale ΛR=1ΛR=1TeVTeV, the data exclude radion scalar masses between 1.15 and 1.55TeVTeV.