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Raza M. Syed

Publications and source records attributed to Raza M. Syed.

At least 19 recordsLinked to original sources

A natural MSSM from a novel $\mathsf{SO(10)}$, Yukawa unification, light sparticles, and SUSY implications at LHC

The $\mathsf{SO(10)}$ model with a heavy Higgs spectrum consisting of $\mathsf{560+\overline{560}}$ and a light Higgs spectrum consisting of $2\mathsf{\times 10+320}$ plet representations of $\mathsf{SO(10)}$ is unique among $\mathsf{SO(10)}$ models.,It has the remarkable property that VEVs of $\mathsf{560}$ and $\mathsf{\overline{560}}$ can simultaneously reduce the rank of the gauge group and further reduce the remaining symmetry down to the standard model gauge group. Additionally, on mixing with the light fields all the Higgs fields become heavy except for one pair of light Higgs doublets just as in MSSM. This model has not been fully explored thus far because of the technical difficulty of computing the couplings of the heavy and the light Higgs sectors, specifically the interaction $(\mathsf{560\times 560)\cdot 320}$ involving the coupling of tensor-spinors with a third rank ~mixed tensor $\mathsf{320}$. An explicit analysis of such couplings is given in this paper. Spontaneous symmetry breaking of the $\mathsf{SO(10)}$ symmetry is carried out reducing the gauge group to $\mathsf{SU(3)}_c\times \mathsf{SU(2)}_L\times \mathsf{U(1)}_Y$ with just one just pair of light Higgs. Thus a natural deduction of MSSM arises from the $\mathsf{SO(10)}$ model with no fine tuning needed. Further, it is shown that the light Higgs doublet of the model is a linear combination of the Higgs doublet fields of the $2\mathsf{\times 10}$ and the $\mathsf{320}$ Higgs fields. It is shown that in this class of $\mathsf{SO(10)}$ models $b-t-τ$ unification can be achieved with $\tanβ$ as low as 5-10. An analysis of the sparticle spectrum within ${\tilde g}$SUGRA renormalization group evolution is given which leads to a bi-modal sparticle spectrum consisting of a compressed low mass spectrum for sleptons and weakinos and a high mass spectrum of gluino, squarks, and heavy Higgs.LHC.

hep-ph

Tests of gluino-driven radiative breaking of the electroweak symmetry at the LHC

The recent muon $g-2$ result from Fermilab combined with the Brookhaven result, strongly points to new physics beyond the Standard Model which can be well described by the electroweak sector of supersymmetry if the masses of the sleptons and some of the electroweak gauginos are in the few hundred GeV range. However, the Higgs boson mass measurement at 125 GeV indicates a mass scale for squarks which lies in the few TeV region indicating a split mass spectrum between squarks and sleptons. This apparent puzzle is resolved in a natural way in gluino-driven radiative breaking of the electroweak symmetry where radiative breaking is driven by a large gluino mass and the gluino color interactions lead to a large splitting between the squarks and the sleptons. We show that an analysis without prejudice using an artificial neural network also leads to the gluino-driven radiative breaking. We use a set of benchmarks and a deep neural network analysis to test the model for the discovery of light sleptons and sneutrinos at HL-LHC and HE-LHC.

hep-ph

Using C++ to Calculate $\mathsf{SO(10)}$ Tensor Couplings

\noindent Model building in $\mathsf{SO(10)}$, which is the leading grand unification framework, often involves large Higgs representations and their couplings. Explicit calculations of such couplings is a multi-step process that involves laborious calculations that are time-consuming and error-prone, an issue which only grows as the complexity of the coupling increases. Therefore, there exists an opportunity to leverage the abilities of computer software in order to algorithmically perform these calculations on-demand. This paper outlines the details of such a software, implemented in C++ using in-built libraries. The software is capable of accepting invariant couplings involving an arbitrary number of $\mathsf{SO(10)}$ Higgs tensors, each having up to 5 indices. The output is then produced in \LaTeX, so that it is universally readable and sufficiently expressive. Through the use of this software, $\mathsf{SO(10)}$ coupling analysis can be performed in a way that minimizes calculation time, eliminates errors, and allows for experimentation with couplings that have not been computed before in the literature. Furthermore, this software can be expanded in the future to account for similar Higgs-Spinor coupling analysis, or extended to include further $\mathsf{SO(N)}$ invariant couplings.

hep-ph

Future searches for SUSY at the LHC post Fermilab $(g-2)_μ$

We assess the future directions for the search for supersymmetry at the Large Hadron Collider in view of the new precision results on the muon anomaly by the Fermilab Collaboration. The existence of a deviation of size 4.1$σ$ from the Standard Model prediction points to light sleptons and light weakinos in the mass range of few hundred GeV while the observation of the Higgs boson mass at $\sim 125$ GeV points to squark masses lying in the few TeV range. Thus a split sparticle spectrum is indicated. We discuss the possibility of such a split sparticle spectrum in the supergravity unified model and show that a splitting of the sfermion spectrum into light sleptons and heavy squarks naturally arises within radiative breaking of the electroweak symmetry driven by heavy gluinos ($\tilde g$SUGRA). We discuss the possible avenues for the discovery of supersymmetry at the LHC within this framework under the further constraint of the recent muon anomaly result from the Fermilab Collaboration. We show that the most likely candidates for early discovery of a sparticle at the LHC are the chargino, the stau, the smuon and the selectron. We present a set of benchmarks and discuss future directions for further work. Specifically, we point to the most promising channels for SUSY discovery and estimate the integrated luminosity needed for the discovery of these benchmarks at the High Luminosity LHC and also at the High Energy LHC.

hep-ph

Yukawa coupling unification in an $\mathsf{SO(10)}$ model consistent with Fermilab $(g-2)_μ$ result

We investigate the Yukawa coupling unification for the third generation in a class of $\mathsf{SO(10)}$ unified models which are consistent with the 4.2 $σ$ deviation from the standard model of the muon $g-2$ seen by the Fermilab experiment E989. A recent analysis in supergravity grand unified models shows that such an effect can arise from supersymmetric loops correction. Using a neural network, we further analyze regions of the parameter space where Yukawa coupling unification consistent with the Fermilab result can appear. In the analysis we take into account the contributions to Yukawas from the cubic and the quartic interactions. We test the model at the high luminosity and high energy LHC and estimate the integrated luminosities needed to discover sparticles predicted by the model.

hep-ph

Corrections to Yukawa couplings from higher dimensional operators in a natural SUSY $\mathsf{SO(10)}$ and HL-LHC implications

We consider a class of unified models based on the gauge group $\mathsf{SO(10)}$ which with appropriate choice of Higgs representations generate in a natural way a pair of light Higgs doublets needed to accomplish electroweak symmetry breaking. In this class of models higher dimensional operators of the form matter-matter-Higgs-Higgs in the superpotential after spontaneous breaking of the GUT symmetry generate contributions to Yukawa couplings which are comparable to the ones from cubic interactions. Specifically we consider an $\mathsf{SO(10)}$ model with a sector consisting of $\mathsf{126+\overline{126} + 210}$ of heavy Higgs which breaks the GUT symmetry down to the standard model gauge group and a sector consisting of $2\times \mathsf{10+120}$ of light Higgs fields. In this model we compute the corrections from the quartic interactions to the Yukawa couplings for the top and the bottom quarks and for the tau lepton. It is then shown that inclusion of these corrections to the GUT scale Yukawas allows for consistency of the top, bottom and tau masses with experiment for low $\tanβ$ with a value as low as $\tanβ$ of 5$-$10. We compute the sparticle spectrum for a set of benchmarks and find that satisfaction of the relic density is achieved via a compressed spectrum and coannihilation and three sets of coannihilations appear: chargino-neutralino, stop-neutralino and stau-neutralino. We investigate the chargino-neutralino coannihilation in detail for the possibility of observation of the light chargino at the high luminosity LHC (HL-LHC) and at the high energy LHC (HE-LHC) which is a possible future 27 TeV hadron collider. It is shown that all benchmark models but one can be discovered at HL-LHC and all would be discoverable at HE-LHC. The ones discoverable at both machines require a much shorter time scale and a lower integrated luminosity at HE-LHC.

hep-ph

A Stronger Case for Superunification Post Higgs Boson Discovery

Supersymmetry and more specifically supergravity grand unification allow one to extrapolate physics from the electroweak scale up to the grand unification scale consistent with electroweak data. Here we give a brief overview of their current status and show that the case for supersymmetry is stronger as a result of the Higgs boson discovery with a mass measurement at $\sim 125$ GeV consistent with the supergravity grand unification prediction that the Higgs boson mass lie below 130 GeV. Thus the discovery of the Higgs boson and the measurement of its mass provide a further impetus for the search for sparticles to continue at the current and future colliders.

hep-ph

An Analysis of B-L=-2 Operators from Matter-Higgs Interactions in a Class of Supersymmetric SO(10) Models

Recently interest in GUT baryogenesis has been resurrected due to the observation that B-violating dimension seven operators that arise in grand unified theories that also violate B-L produce baryon asymmetry that cannot be wiped out by sphaleron processes. While a general analysis of such higher dimensional operators from a bottom up approach exists in the literature, a full analysis of them derived from grand unification does not exist. In this work we present a complete analysis of B-L=-2 operators within a realistic SO(10) grand unification where the doublet-triplet splitting is automatic via a missing partner mechanism. Specifically we compute all allowed dimension five, dimension seven and dimension nine operators arising from matter-Higgs interactions. The relative strength of all the allowed B-L=-2 operators is given. Such interactions are useful in the study of neutrino masses, baryogenesis, proton decay and $n-\bar n$ oscillations within a common realistic grand unification framework.

hep-ph

Variety of SO(10) GUTs with Natural Doublet-Triplet Splitting via the Missing Partner Mechanism

We present a new class of unified SO(10) models where the GUT symmetry breaking down to the standard model gauge group involves just one scale, in contrast to the conventional SO(10) models which require two scales. Further, the models we discuss possess a natural doublet-triplet splitting via the missing partner mechanism without fine tuning. Such models involve $560+\ov{560}$ pair of heavy Higgs fields along with a set of light fields. The $560+\ov{560}$ are the simplest representations of SO(10) besides the $126+\ov{126}$ which contain an excess of color triplets over $SU(2)_L$ doublets. We discuss several possibilities for realizing the missing partner mechanism within these schemes. With the $126+\ov{126}$ multiplets, three viable models are found with additional fields belonging to ${210 + 2 \times 10 + 120}$, ${45 + 10 + 120}$, or ${210 + 16 + \ov{16} + 10 + 120}$. With the $560+\ov{560}$, a unique possibility arises for the missing partner mechanism, with additional ${2\times 10+ 320}$ fields. These models are developed in some detail. It is shown that fully realistic fermion masses can arise in some cases, while others can be made realistic by addition of vector--like representations. Naturally large neutrino mixing angles, including sizable $θ_{13}$, can emerge in these models. The couplings of the $H_u(H_d)$ Higgs doublets of the MSSM which give masses to the up quarks (down quarks and leptons) are not necessarily equal at the grand unification scale and would lead to a new phenomenology at the low energy scales.

hep-ph

Tiger Tales: A Critical Examination of the Tiger's Enclosure at the San Francisco Zoo

Given the recent tragedy involving a 350 pound Siberian Tiger and the death of teenager Carlos Souza Jr., one must ask a fundamental question: Can a tiger overcome an obstacle that is thirty-three feet away and twelve and a half feet tall? Are these dimensions sufficient enough to protect the zoo-visitors from a potential escape and/or attack? To answer these questions we use simple two-dimensional projectile motion to find the minimum velocity a tiger needs in order to clear the obstacle. With our results we conclude that it is highly likely that the tiger was able to leap over the obstacle with ease!

physics.soc-ph

Problems and Solutions in a Graduate Course in Classical Electrodynamics (1)

The following is the very first set of the series in 'Problems and Solutions in a Graduate Course in Classical Electrodynamics'. In each of the sets of the problems we intend to follow a theme, which not only makes it unique but also deals with the investigation of a certain class of problems in a thorough and rigorous manner. Figures are not included.

physics.class-ph

Suppression of Higgsino mediated proton decay by cancellations in GUTs and strings

A mechanism for the enhancement for proton lifetime in supersymmetric/supergravity (SUSY/SUGRA) grand unified theories (GUTs) and in string theory models is discussed where Higgsino mediated proton decay arising from color triplets (anti-triplets) with charges $Q=-1/3(1/3)$ and $Q=-4/3(4/3)$ is suppressed by an internal cancellation due to contributions from different sources. We exhibit the mechanism for an SU(5) model with $45_H+\bar{45}_H$ Higgs multiplets in addition to the usual Higgs structure of the minimal model. This model contains both $Q=-1/3(1/3)$ and $Q=-4/3(4/3)$ Higgs color triplets (anti-triplets) and simple constraints allow for a complete suppression of Higgsino mediated proton decay. Suppression of proton decay in an SU(5) model with Planck scale contributions is also considered. The suppression mechanism is then exhibited for an SO(10) model with a unified Higgs structure involving $144_H+\bar{144}_H$ representations.The SU(5) decomposition of $144_H+\bar{144}_H$ contains $5_H+\bar 5_H$ and $45_H+\bar{45}_H$ and the cancellation mechanism arises among these contributions which mirrror the SU(5) case. The cancellation mechanism appears to be more generally valid for a larger class of unification models. Specifically the cancellation mechanism may play a role in string model constructions to suppress proton decay from dimension five operators. The mechanism allows for the suppression of proton decay consistent with current data allowing for the possibility that proton decay may be visible in the next round of nucleon stability experiment.

hep-ph

Fermion Mass Generation in SO(10) with a Unified Higgs Sector

An analysis of generating fermion masses via cubic couplings in SO(10) grand unification with a unified Higgs sector is given. The new framework utilizes a single pair of vector--spinor representation $144+\bar{144}$ to break the gauge symmetry all the way to $SU(3)_C \times U(1)_{em}$. Typically the matter--Higgs couplings in this framework are quartic and lead to naturally suppressed Yukawa couplings for the first two generations. Here we show that much larger third generation couplings naturally arise at the cubic level with additional matter in 10--plet and 45--plet representations of SO(10). Thus the physical third generation is a mixture of 16, 10 and 45--plet representations while the remaining components become superheavy and are removed from the low energy spectrum. In this scenario it is possible to understand the heaviness of the top in a natural way since the analysis generates a hierarchy in the Yukawa couplings so that $h_{\textnormal {t}}/h_{\textnormal {b}}>> 1$ where $h_{\textnormal {t}} (h_{\textnormal {b}})$ are the top (bottom) Yukawa couplings. It is then possible to realize values of $\tanβ$ as low as 2, which also helps to stabilize the proton.

hep-ph

Couplings of Vector-Spinor Representation for SO(10) Model Building

Higgs multiplet in the vector-spinor representations of SO(10), i.e., the $144+\bar{144}$ multiplet can break the SO(10) gauge symmetry spontaneously in one step down to the Standard Model gauge group symmetry $SU(3)_C\times SU(2)_L\times U(1)_Y$ and a recent analysis has used such vector-spinors for building a new class of SO(10) grand unification models (hep-ph/0506312) . Here we discuss the techniques for the computation of several classes of vector-spinor couplings using the Basic Theorem on the SO(2N) vertex expansion developed by the authors. The computations include the cubic couplings of the vector-spinors with SO(10) tensors, quartic self-couplings of the vector-spinors, and couplings of the vector-spinors with spinor representations of SO(10). The last set include couplings of vector-spinors with the 16-plets of quarks and lepton and with the 16 and $\bar{16}$ of Higgs. These couplings provide a crucial tool for further development of the SO(10) grand unification using vector-spinor representations. These include study of quark-lepton masses, analysis of dimension five operators including baryon and lepton number violating operators, and study of neutrino masses and mixings. Illustrative examples are given for their computation using a sample of vector-spinor couplings.

hep-ph

Couplings in SO(10) Grand Unification

In this thesis, we develop techniques for the analysis of SO(2N) invariant couplings which allows a full exhibition of the SU(N) invariant content of the spinor and tensor representations. The techniques utilize a so called Basic Theorem which we first derive. Using this method an evaluation of the trilinear couplings of the 16 plet of matter and of the 16 and $\bar{16}$ plets Higgs is given. In particular, we give a full determination of couplings in their SU(5) decomposed form, involving $16 16$ and the 10, 120 and $\bar{126}$ tensor fields together with $\bar{16} 16$ ($16 \bar{16}$) and the 1, 45 and 210 tensor fields. We also compute the vector couplings of $16 16$ ($\bar{16} \bar{16}$) and the 1, 45, 210 gauge fields. Computation of dimension-5 operators formed from 16 and $\bar {16}$ arising from the mediation of 1, 10, 45 and 210 plet of heavy Higgs, are also analyzed. Complete supersymmetric vector couplings belonging to the singlet and the adjoint representation of the SO(10) gauge group are computed in the Wess-Zumino gauge. An $SU(5)\times U(1)$ decomposition of the vector couplings ${16}-16-210$ is completely carried out using the Wess-Zumino gauge and its transition to a non linear sigma type model is shown. The utility of these results in the analysis of quark-lepton textures and of proton decay is briefly discussed. Possible future applications of the techniques given here such as in the development of string landscape SO(10) type models is briefly pointed out.

hep-ph

A Unified Framework for Symmetry Breaking in SO(10)

A new SO(10) unified model is proposed based on a one step breaking of SO(10) to the Standard Model gauge group $SU(3)\times SU(2)\times U(1)_Y$ using a single 144 of Higgs. The symmetry breaking occurs when the SU(5) 24-plet component of 144 develops a vacuum expectation value. Further, it is possible to obtain from the same 144 a light Higgs doublet necessary for electro-weak symmetry breaking using recent ideas of string vacua landscapes and fine tuning. Thus the breaking of SO(10) down to $SU(3)_C\times U(1)_{em}$ can be accomplished with a single Higgs. We analyze this symmetry breaking pattern in the nonsupersymmetric as well as in the supersymmetric SO(10) model.In this scenario masses of the quarks and leptons arise via quartic couplings. We show that the resulting mass pattern is consistent with experimental data, including neutrino oscillations. The model represents an alternative to the currently popular grand unified scenarios.

hep-ph

Areal Optimization of Polygons

We will first solve the following problem analytically: given a piece of wire of specified length, we will find where the wire should be cut and bent to form two regular polygons not necessarily having the same number of sides, so that the combined area of the polygons thus formed is maximized, minimized, greater than, and less than a specified area. We will extend the results to the cases where the wire is divided into three and finally into an arbitrary number of segments. The second problem we will solve is as follows: two wires of specified length are to be bent into two regular polygons whose total number of sides is fixed. We will determine how the total number of polygonal sides are to be allocated between the wires so that the total area of the polygons is maximized. We will extend the results found here to the case where we are given any number of wires of specified length.

math.HO

Coupling the Supersymmetric 210 Vector Multiplet to Matter in SO(10)

An analysis of the couplings of the 210 dimensional SO(10) vector multiplet to matter is given. Specifically we give an $SU(5)\times U(1)$ decomposition of the vector couplings $\bar{16}_{\pm}-16_{\pm}-210$, where $16_{\pm}$ is the semispinor of SO(10) chirality ${\pm}$, using a recently derived basic theorem. The analysis is carried out using the Wess-Zumino gauge. However, we also consider the more general situation where all components of the vector multiplet enter in the couplings with the chiral fields. Here elimination of the auxiliary fields leads to a sigma model type nonlinear Lagrangian. Interactions of the type analysed here may find applications in effective theories with the 210 vector arising as a condensate. The analysis presented here completes the explicit computation of all lowest order couplings involving the $16_{\pm}$ of spinors with Higgs and vectors multiplets using the basic theorem.

hep-th