Sujeet Akula

Monash University, School of Physics, Post-Doc

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I am presently a graduate student at Northeastern University's Department of Physics, and my primary interests are HEP theory and phenomenology.

I briefly worked for the IceCube collaboration at UW-Madison. I attended UW-Milwaukee for undergraduate degrees in Computer Science and Applied Math & Physics.
Phone: +1 (617) 652-0261

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Papers by Sujeet Akula

Gluino-driven Radiative Breaking, Higgs Boson Mass, Muon g−2, and the Higgs Diphoton Decay in SUGRA Unification

We attempt to reconcile seemingly conflicting experimental results on the Higgs boson mass, the a... more We attempt to reconcile seemingly conflicting experimental results on the Higgs boson mass, the anomalous magnetic moment of the muon, null results in search for supersymmetry at the LHC within the 8 TeV data and results from B-physics, all within the context of supersymmetric grand unified theories. Specifically, we consider a supergravity grand unification model with non-universal gaugino masses where we take the SU(3)C gaugino field to be much heavier than the other gaugino and sfermion fields at the unification scale. This construction naturally leads to a large mass splitting between the slepton and squark masses, due to the mass splitting between the electroweak gauginos and the gluino. The heavy Higgs bosons and Higgsinos also follow the gluino toward large masses. We carry out a Bayesian Monte Carlo analysis of the parametric space and find that it can simultaneously explain the large Higgs mass, and the anomalous magnetic moment of the muon, while producing a negligible correction to the Standard Model prediction for Br(B0s→μ+μ−). We also find that the model leads to an excess in the Higgs diphoton decay rate. A brief discussion of the possibility of detection of the light particles is given. Also discussed are the implications of the model for dark matter.

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Implications of the Higgs Boson Discovery for mSUGRA

A Bayesian analysis is carried out to identify the consistent regions of the mSUGRA parameter spa... more A Bayesian analysis is carried out to identify the consistent regions of the mSUGRA parameter space, where the newly-discovered Higgs boson's mass is used as a constraint, along with other experimental constraints. It is found that m1/2 can lie in the sub TeV region, A0/m0 is mostly confined to a narrow strip with |A0/m0|≤1, while m0 is typically a TeV or larger. Further, the Bayesian analysis is used to set 95% CL lower bounds on sparticle masses. Additionally, it is shown that the spin independent neutralino-proton cross section lies just beyond the reach of the current sensitivity but within the projected sensitivity of the SuperCDMS-1T and XENON-1T experiments, which explains why dark matter has thus far not been detected. The light sparticle spectrum relevant for the discovery of supersymmetry at the LHC are seen to be the gluino, the chargino and the stop with the gluino and the chargino as the most likely candidates.

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Higgs Boson Mass Predictions in SUGRA Unification and Recent LHC-7 Results

LHC-7 has narrowed down the mass range of the light Higgs boson. This result is consistent with t... 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. The implications of light Higgs boson in the broader mass range of 115 GeV to 131 GeV and a narrower range of 123 GeV to 127 GeV are explored in the context of the discovery of supersymmetry at LHC-7 and for the observation of dark matter in direct detection experiments.

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Naturalness, Supersymmetry and Implications for LHC and Dark Matter

It is shown that the Hyperbolic Branch of the radiative electroweak symmetry breaking contains in... more It is shown that the Hyperbolic Branch of the radiative electroweak symmetry breaking contains in it three regions: the Focal Point, Focal Curves, and Focal Surfaces. Further, the Focal Point is shown to lie on the boundary of a Focal Curve. These focal regions allow for a small $\mu$ while scalar masses can become large and may lie in the several TeV region. It is shown that for the mSUGRA model the current LHC-7 constraint depletes the Focal Point region while regions on Focal Curves and Focal Surfaces remain largely intact. The LHC implications for models which lie on Focal Curves are briefly discussed as well as the implications of dark matter constraints for the Focal Point, Focal Curves and Focal Surfaces are discussed.

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$Research paper thumbnail of Excess Observed in CDF $B^0_s \to μ^{+} μ^{-}$ and SUSY at the LHC$

Excess Observed in CDF $B^0_s \to μ^{+} μ^{-}$ and SUSY at the LHC

The recent excess observed by CDF in $B^0_s \to \mu^{+} \mu^{-}$ is interpreted in terms of a pos... more The recent excess observed by CDF in $B^0_s \to \mu^{+} \mu^{-}$ is interpreted in terms of a possible supersymmetric origin. An analysis is given of the parameter space of mSUGRA and non-universal SUGRA models under the combined constraints from LHC-7 with 165 pb$^{-1}$ of integrated luminosity, under the new XENON-100 limits on the neutralino-proton spin independent cross section and under the CDF $B^0_s \to \mu^{+} \mu^{-}$ 90% C.L. limit reported to arise from an excess number of dimuon events. It is found that the predicted value of the branching ratio $B^0_s \to \mu^{+} \mu^{-}$ consistent with all the constraints contains the following set of NLSPs: chargino, stau, stop or CP odd (even) Higgs. The lower bounds of sparticles, including those from the LHC, XENON and CDF $B^0_s\to \mu^+\mu^-$ constraint, are exhibited and the shift in the allowed range of sparticle masses arising solely due to the extra constraint from the CDF result is given. It is pointed out that the two sided CDF 90% C.L. limit puts upper bounds on sparticle masses. An analysis of possible signatures for early discovery at the LHC is carried out corresponding to the signal region in $B^0_s \to \mu^{+} \mu^{-}$. Implications of GUT-scale non-universalities in the gaugino and Higgs sectors are discussed. If the excess seen by the CDF Collaboration is supported by further data from LHCb or D0, this new result could be a harbinger for the discovery of supersymmetry.

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New Constraints on Dark Matter from CMS and ATLAS Data

Constraints on dark matter from the first CMS and ATLAS SUSY searches are investigated. It is sho... more Constraints on dark matter from the first CMS and ATLAS SUSY searches are investigated. It is shown that within the minimal supergravity model, the early search for supersymmetry at the LHC has depleted a large portion of the signature space in dark matter direct detection experiments. In particular, the prospects for detecting signals of dark matter in the XENON and CDMS experiments are significantly affected in the low neutralino mass region. Here the relic density of dark matter typically arises from slepton coannihilations in the early universe. In contrast, it is found that the CMS and ATLAS analyses leave untouched the Higgs pole and the Hyperbolic Branch/Focus Point regions, which are now being probed by the most recent XENON results. Analysis is also done for supergravity models with non-universal soft breaking where one finds that a part of the dark matter signature space depleted by the CMS and ATLAS cuts in the minimal SUGRA case is repopulated. Thus, observation of dark matter in the LHC depleted region of minimal supergravity may indicate non-universalities in soft breaking.

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Interpreting the First CMS and ATLAS SUSY Results

The CMS and the ATLAS Collaborations have recently reported on the search for supersymmetry with ... more The CMS and the ATLAS Collaborations have recently reported on the search for supersymmetry with 35 pb$^{-1}$ of data and have put independent limits on the parameter space of the supergravity unified model with universal boundary conditions at the GUT scale for soft breaking, i.e., the mSUGRA model. We extend this study by examining other regions of the mSUGRA parameter space in $A_0$ and $\tan\beta$. Further, we contrast the reach of CMS and ATLAS with 35 pb$^{-1}$ of data with the indirect constraints, i.e., the constraints from the Higgs boson mass limits, from flavor physics and from the dark matter limits from WMAP. Specifically it is found that a significant part of the parameter space excluded by CMS and ATLAS is essentially already excluded by the indirect constraints and the fertile region of parameter space has yet to be explored. We also emphasize that gluino masses as low as 400 GeV but for squark masses much larger than the gluino mass remain unconstrained and further that much of the hyperbolic branch of radiative electroweak symmetry breaking, with low values of the Higgs mixing parameter $\mu$, is essentially untouched by the recent LHC analysis.

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