119238429
Sensitivity of an Upgraded LHC to R-Parity Violating Signatures of the MSSM
We present a sensitivity study for the pair-production of supersymmetric particles which decay through R-parity violating channels. As the scope of possible RPV signatures is very broad, the reach of several selected signatures spanning a representative variety of possible final states is considered. Preference in representation is given to spectra motivated by naturalness, i.e. light higgsinos, stops and gluinos. The sensitivity studies are presented for proton-proton collisions at 14 TeV with an integrated luminosity of 300 and 3000 fb^-1, as well as at 33 TeV with an integrated luminosity of 3000 fb^-1.
118632441
Possibility of early Higgs boson discovery in nonminimal Higgs sectors
Particle physics models with more than one Higgs boson occur in many frameworks for physics beyond the standard model, including supersymmetry, technicolor, composite Higgs, and ''little Higgs'' models. If the Higgs sector contains couplings stronger than electroweak gauge couplings, there will be heavy Higgs particles that decay to lighter Higgs particles plus heavy particles such as W, Z, and t. This motivates searches for final states involving multiple W, Z, t, and bb pairs. A two Higgs doublet model with custodial symmetry is a useful simplified model to describe many of these signals. The model can be parameterized by the physical Higgs masses and the mixing angles {alpha} and {beta}, so discovery or exclusion in this parameter space has a straightforward physical interpretation. We illustrate this with a detailed analysis of the process gg{yields}A followed by A{yields}hZ and h{yields}WW. For m{sub A}{approx_equal}330 GeV, m{sub h}{approx_equal}200 GeV we can get a 4.5{sigma} signal with 1 fb{sup -1} of integrated luminosity at the Large Hadron Collider.
121693849
Searching For Resonances inside Top-like Events
In extended Higgs sectors, heavy Higgs bosons can decay via cascades to a light Higgs boson plus W and Z bosons. We study signals of such sectors at the Tevatron and LHC that result from resonant production of a heavy H{sup 0} followed by the decay H{sup 0} {yields} H{sup {+-}}W{sup {+-}} with H{sup +} {yields} W{sup +}h{sup 0} {yields} W{sup +} b{bar b} or H{sup +} {yields} t{bar b} {yields} W{sup +} b{bar b}. The final states have the same particle content as that of t{bar t} production, but with a resonant structure that can be used to distinguish signal events from background events. We propose analysis techniques and estimate the experimental sensitivity of the Tevatron and LHC experiments to these signals.
119264520
LHC coverage of RPV MSSM with light stops
A bstractWe examine the sensitivity of recent LHC searches to signatures of supersymmetry with R-parity violation (RPV). Motivated by naturalness of the Higgs potential, which would favor light third-generation squarks, and the stringent LHC bounds on spectra in which the gluino or first and second generation squarks are light, we focus on scenarios dominated by the pair production of light stops. We consider the various possible direct and cascade decays of the stop that involve the trilinear RPV operators. We find that in many cases, the existing searches exclude stops in the natural mass range and beyond. However, typically there is little or no sensitivity to cases dominated by UDD operators or LQD operators involving taus. We propose several ideas for searches which could address the existing gaps in experimental coverage of these signals.
119096508
A swarm of Bs
A bstractNew physics signals containing five or more b-tagged jets, but without T or leptons, could realistically be sitting within the current 8 TeV LHC data set without receiving meaningful constraints from any of the existing LHC searches at either ATLAS or CMS. This work provides several examples of simple, motivated models that yield final states containing many b-jets. To study the potential for uncovering new physics in these high b-jet multiplicity channels, this paper focuses on a natural supersymmetry scenario where each of the pair-produced stops decays to an on-shell chargino, which subsequently decays via an MFV-motivated, R-parity violating coupling. This gives rise to an eight-jet final state containing six b-quarks. Although no public measurements exist, estimates indicate that the standard model backgrounds in high b-jet multiplicity channels should be very small. To circumvent the background uncertainty, an asymmetric method is presented that utilizes two different techniques to conservatively exclude or to discover new physics in high b-jet multiplicity final states.
118601865
Toward full LHC coverage of natural supersymmetry
A bstractWe argue that combining just a handful of searches for new physics at Run I of the LHC is sufficient to exclude most supersymmetric extensions of the Standard Model in which the gluino is kinematically accessible and the spectrum is natural. Such models typically give rise to significant T , top quarks and/or high object multiplicity, and we show that having even one of these signatures generally results in stringent limits. We also identify, among models that lack these signatures, the few gaps in coverage remaining, and propose search strategies to close these gaps. Our results are general and independent of the details of the spectrum, assumptions about minimality, R-parity, etc. Our analysis strategy should remain applicable when the LHC moves to higher energy. Central to our argument are ATLAS and CMS searches for many jets and low T , a proposed lepton + many jets search, an ATLAS search for 6-7 high-pT jets, and a reexamination of the control and signal regions of the CMS black hole search.
122920598
Massive superparticles with Siegel symmetry and their covariant canonical quantisation
Abstract We study massive superparticles with Siegel symmetry as toy models of the Green-Schwarz string, and as mechanics actions furnishing minimal representations of supersymmetry upon quantisation. A general construction yielding all such theories is given, and it is shown that the simplest class can be derived from massless models in higher dimensions. We consider the quantisation of massive superparticles using the canonical methods of Dirac, and show that the first-class and second-class constraints can always be defined so as to respect all global symmetries, giving a completely covariant method of quantisation. (This cannot be done in the massless case.) The quantisation is carried out explicitly for the simplest class of models: Dirac brackets are computed and all necessary consistency checks performed. We prove that no operator-ordering problems arise by finding a set of variables for which the covariant Dirac brackets become free canonical graded commutation relations. By considering features shared by massive superparticles and the Green-Schwarz string (but not present for massless superparticles) we argue that the latter should admit a similar covariant quantisation.
121797186
Complex Toda theories and twisted reality conditions
The Toda equations (based on a finite-dimensional or affine Lie algebra of superalgebra) are discussed as integrable non-linear differential equations for a set of complex scalar fields. We show that such complex Toda fields can either be restricted to take real values the standard way or else they can be subjected to a “twisted” reality condition associated to any Z2 symmetry of the Cartan matrix of Dynkin diagram of the underlying algebra. Different reality conditions give rise to different lagrangian field theories. In the conformal case, however, these theories have the same central charge, while in the affine case they have the same mass spectrum. The construction of N = 2 superconformal theories based on the superalgebras A(n, n−1) is clarified, and a new class of conformal field theories with positive kinetic energy based on the superalgebras C(n) is presented. The ideas developed are also relevant to understanding soliton solutions in affine Toda theories with imaginary coupling constant.
119053557
Geometry and Dynamics with Time-Dependent Constraints
We describe how geometrical methods can be applied to a system with explicitly time-dependent second-class constraints so as to cast it in Hamiltonian form on its physical phase space. Examples of particular interest are systems which require time-dependent gauge fixing conditions in order to reduce them to their physical degrees of freedom. To illustrate our results we discuss the gauge-fixing of relativistic particles and strings moving in arbitrary background electromagnetic and antisymmetric tensor fields.
16517190
Exact scattering in the SU(n) supersymmetric principal chiral model
Abstract The complete spectrum of states in the supersymmetric principal chiral model based on SU(n) is conjectured, and an exact factorizable S-matrix is proposed to describe scattering amongst these states. The SU(n)L × SU(n)R symmetry of the Lagrangian is manifest in the S-matrix construction. The supersymmetries, on the other hand, are incorporated in the guise of spin - 1 2 charges acting on a set of RSOS kinks associated with su(n) at level n. To test the proposed S-matrix, calculations of the change in the ground-state energy in the presence of a coupling to a background charge are carried out. The results derived from the Lagrangian using perturbation theory and from the S-matrix using the TBA are found to be in complete agreement for a variety of background charges which pick out, in turn, the highest weight states in each of the fundamental representations of SU(n). In particular, these methods rule out the possibility of additional CDD factors in the S-matrix. Comparison of the expressions found for the free-energy also yields an exact result for the mass gap in these models: m Λ MS = ( n π ) sin ( π n ) .
123140877
Supersymmetric Toda field theories
We analyse a class of integrable two-dimensional field theories with N =1 and N = 2 supersymmetry via the Lax, or zero-curvature, construction based on a Lie superalgebra. Some of the theories exhibit extended superconformal symmetries, generalizing the bosonic W-algebras. We also investigate the possible integrable deformations of these models and find that in some cases supersymmetry is broken and in other cases it is preserved.