B. Altunkaynak - Northeastern University

B. Altunkaynak
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B. Altunkaynak
Northeastern University
United States

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Pub Categories

High Energy Physics - Phenomenology (13)
High Energy Physics - Experiment (3)
Mathematics - Combinatorics (1)
High Energy Astrophysical Phenomena (1)
High Energy Physics - Theory (1)

Publications Authored By B. Altunkaynak

Collider events with multi-stage cascade decays fill out the kinematically allowed region in phase space with a density that is enhanced at the boundary. The boundary encodes all available information about the spectrum and is well populated even with moderate signal statistics due to this enhancement. In previous work, the improvement in the precision of mass measurements for cascade decays with three visible and one invisible particles was demonstrated when the full boundary information is used instead of endpoints of one-dimensional projections. Read More

The search for supersymmetry at Run 1 of LHC has resulted in gluino mass limits m(gluino)>~ 1.3 TeV for the case where m(gluino)<Read More

A general two Higgs doublet model (2HDM) is adopted to study the signature of flavor changing neutral Higgs (FCNH) decay $\phi^0 \to t\bar{c}+\bar{t}c$, where $\phi^0$ could be a CP-even scalar ($H^0$) or a CP-odd pseudoscalar ($A^0$). Measurement of the light 125 GeV neutral Higgs boson ($h^0$) couplings at the Large Hadron Collider (LHC) favor the decoupling limit or the alignment limit of a 2HDM, in which gauge boson and diagonal fermion couplings of $h^0$ approach Standard Model values. In such limit, FCNH couplings of $h^0$ are naturally suppressed by a small mixing parameter $\cos(\beta-\alpha)$, while the off-diagonal couplings of heavier neutral scalars $\phi^0$ are sustained by $\sin(\beta-\alpha) \sim 1$. Read More

Sparticle mass hierarchies contain significant information regarding the origin and nature of supersymmetry breaking. The hierarchical patterns are severely constrained by electroweak symmetry breaking as well as by the astrophysical and particle physics data. They are further constrained by the Higgs boson mass measurement. Read More

We investigate the prospects for the discovery of neutral Higgs bosons produced with a bottom quark where the Higgs decays into a pair of tau leptons and the taus decay into an electron-muon pair, i.e. $bg \to b\phi^0 \to b\tau^+\tau^- \to be^\pm\mu^\mp + E\!\!\!/_T$, $\phi^0 = h^0, H^0, A^0$. Read More

LHC-7 has narrowed down the mass range of the light Higgs boson. This result is consistent with the supergravity unification framework, and the current Higgs boson mass window implies a rather significant loop correction to the tree value pointing to a relatively heavy scalar sparticle spectrum with universal boundary conditions. It is shown that the largest value of the Higgs boson mass is obtained on the Hyperbolic Branch of radiative breaking. Read More

With the aim of uncovering viable regions of parameter space in deflected mirage mediation (DMM) models of supersymmetry breaking, we study the landscape of particle mass hierarchies for the lightest four non-Standard Model states for DMM models and compare the results to that of minimal supergravity/constrained MSSM (mSUGRA/CMSSM) models, building on previous studies of Feldman, Liu, and Nath. Deflected mirage mediation is a string-motivated scenario in which the soft terms include comparable contributions from gravity mediation, gauge mediation, and anomaly mediation. DMM allows a wide variety of phenomenologically preferred models with light charginos and neutralinos, including novel patterns in which the heavy Higgs particles are lighter than the lightest superpartner. Read More

We carry out an analysis of the potential of the Large Hadron Collider (LHC) to discover supersymmetry in runs at $\sqrt s=7$ TeV with an accumulated luminosity of (0.1--2) fb$^{-1}$ of data. The analysis is done both with minimal supergravity (mSUGRA) and supergravity (SUGRA) models with non-universal soft breaking. Read More

We compare the collider phenomenology of mirage mediation and deflected mirage mediation, which are two recently proposed "mixed" supersymmetry breaking scenarios motivated from string compactifications. The scenarios differ in that deflected mirage mediation includes contributions from gauge mediation in addition to the contributions from gravity mediation and anomaly mediation also present in mirage mediation. The threshold effects from gauge mediation can drastically alter the low energy spectrum from that of pure mirage mediation models, resulting in some cases in a squeezed gaugino spectrum and a gluino that is much lighter than other colored superpartners. Read More

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Read More

An algorithm is developed which the goal of producing the most statistically significant signature list for distinguishing between two candidate models given a set of LHC observations. Read More

Affiliations: 1Northeastern University, 2University of Michigan, 3Northeastern University, 4University of Michigan, 5Northeastern University

We begin a systematic study of how gaugino mass unification can be probed at the CERN Large Hadron Collider (LHC) in a quasi-model independent manner. As a first step in that direction we focus our attention on the theoretically well-motivated mirage pattern of gaugino masses, a one-parameter family of models of which universal (high scale) gaugino masses are a limiting case. We improve on previous methods to define an analytic expression for the metric on signature space and use it to study one-parameter deviations from universality in the gaugino sector, randomizing over other soft supersymmetry-breaking parameters. Read More

Affiliations: 1Northeastern University, 2Northeastern University, 3Northeastern University

We investigate the utility of cosmological and astrophysical observations for distinguishing between supersymmetric theories. In particular we consider 276 pairs of models that give rise to nearly identical patterns of observables at hadron colliders. Despite inherent uncertainties in such things as the local halo density model, or background rates from astrophysical sources, we find observations associated with stable relic neutralinos can be a surprisingly effective discriminant between candidate theories. Read More

This work is intended as an attempt to study the non-perturbative renormalization of bound state problem of finitely many Dirac-delta interactions on Riemannian manifolds, S^2, H^2 and H^3. We formulate the problem in terms of a finite dimensional matrix, called the characteristic matrix. The bound state energies can be found from the characteristic equation. Read More

A method for converting the geometrical problem of rectangle packing to an algebraic problem of solving a system of polynomial equations is described. Read More