A bstract We present a novel possibility that a network of domain walls bounded by cosmic strings generates a stochastic gravitational wave background (SWGB) signal originating from the spontaneous breaking of a gauged U(1) F flavor symmetry and the subsequent breaking of discrete Z 2 symmetry that accommodates dark matter. The gravitational wave (GW) spectrum produced by the string-bounded-wall network can be detected for high U(1) F breaking scales in forthcoming GW detectors including LISA, ET and SKA. The GW signal exhibits a distinctive frequency slope, in the infrared, compared to the standard cosmic-string case, in the frequency range between micro-hertz and hertz. We develop a possible strategy to distinguish and characterize GW spectrum of the hybrid defect from other defects, such as stable cosmic strings, via employing the exact calculation with a machine-learning surrogate based on a multilayer perceptron (MLP), trained on spectra obtained from the full numerical treatment. This is then used for rapid inference in the detector-specific signal-to-noise ratio (SNR) computation which also makes the process fast and efficient. We also discuss some possible complementarity between GW searches and Flavor observables in the laboratory.

Baryon number conservation is not guaranteed by any fundamental symmetry within the Standard Model, and therefore has been a subject of experimental and theoretical scrutiny for decades. So far, no evidence for baryon number violation has been observed. Large underground detectors have long been used for both neutrino detection and searches for baryon number violating processes. The next generation of large neutrino detectors will seek to improve upon the limits set by past and current experiments and will cover a range of lifetimes predicted by several Grand Unified Theories. In this White Paper, we summarize theoretical motivations and experimental aspects of searches for baryon number violation in neutrino experiments.

Abstract We examine proton decay mediated by color-triplet Higgsinos in minimal supersymmetric SU(5) grand unified theory in light of the discovery of the Higgs boson and the absence of SUSY signals at the LHC. We pay special attention to various threshold effects arising from Planck-suppressed operators that affect the color-triplet Higgsino mass and also allow for correcting the wrong mass relations for the light fermions. Our analysis allows for a non-universal SUSY spectrum with the third family sfermions having a separate mass compared to the first two families. We identify the allowed parameter space of the model and show that the SUSY scalar masses are constrained by current limits from proton lifetime to be above 5 TeV, while the glunio, Wino and the Higgsinos may be within reach of the LHC. When the SUSY scalar masses are required to be ≤ 30 TeV, so that they are within reach of next generation collider experiments, we find that proton lifetime for the decay p → $$ \overline{\nu} $$ ν ¯ K+ is bounded by τ(p → $$ \overline{\nu} $$ ν ¯ K+) ≤ 1.1 × 1035 yrs.

We present a class of nonsupersymmetric models in which the so-called critical Higgs inflation (xi < 100) can be naturally realized without using specific values for Higgs and top quark masses. In these scenarios, the Standard Model (SM) vacuum stability problem, gauge coupling unification, neutrino mass generation and Higgs inflation mechanism are linked to each other. We adopt in our models Type I seesaw mechanism for neutrino masses. An appropriate choice of the Type I seesaw scale allows us to have an arbitrarily small but positive value of SM Higgs quartic coupling around the inflation scale. We present a few benchmark points where we show that the scalar spectral indices are around 0.9626 and 0.9685 for the number of e-folding N = 50 and N = 60, respectively. The tensor-to-scalar ratios are of the order of 10(-3). The running of the scalar spectral index is negative and is of the order of 10(-4).

Giving up the solutions to the fine-tuning problems, we propose the non-supersymmetric flipped \(SU(5)\times U(1)_X\) model based on the minimal particle content principle, which can be constructed from the four-dimensional SO(10) models, five-dimensional orbifold SO(10) models, and local F-theory SO(10) models. To achieve gauge coupling unification, we introduce one pair of vector-like fermions, which form a complete \(SU(5)\times U(1)_X\) representation. The proton lifetime is around \(5\times 10^{35}\) years, neutrino masses and mixing can be explained via the seesaw mechanism, baryon asymmetry can be generated via leptogenesis, and the vacuum stability problem can be solved as well. In particular, we propose that inflaton and dark matter particles can be unified to a real scalar field with \(Z_2\) symmetry, which is not an axion and does not have the non-minimal coupling to gravity. Such a kind of scenarios can be applied to the generic scalar dark matter models. Also, we find that the vector-like particle corrections to the \(B_s^0\) masses might be about 6.6%, while their corrections to the \(K^0\) and \(B_d^0\) masses are negligible.

We propose a SU(3)(C) x SU(2)(L) x SU(2)(N) x U(1)(Y) model arising from E-6 grand unified theory. We show that the tiny neutrino masses in this model can be generated at the three-loop involving the SU(2)(N) gauge bosons. With Yukawa couplings around 0.01 or larger and TeV-scale SU(2)(N) gauge bosons, we show that the neutrino oscillation data can be explained naturally by presenting a concrete benchmark set of input parameters. All new particles are around the TeV scale. Thus our model can be tested at the ongoing/future collider experiments.

We study the possibility of radiative electroweak symmetry breaking where loop corrections to the mass parameter of the Higgs boson trigger the symmetry breaking in various extensions of the Standard Model (SM). Although the mechanism fails in the SM, it is shown to be quite successful in several extensions which share a common feature of having an additional scalar around the TeV scale. The positive Higgs mass parameter at a high energy scale is turned negative in the renormalization group flow to lower energy by the cross couplings between the scalars in the Higgs potential. The type-II seesaw model with a TeV scale weak scalar triplet, a two-loop radiative neutrino mass model with new scalars at the TeV scale, the inert doublet model, scalar singlet dark matter model, and a universal seesaw model with an additional U(1) broken at the TeV scale are studied and shown to exhibit successful radiative electroweak symmetry breaking.

We perform a status analysis of selective supersymmetric GUT models in light of recent constraints from collider and dark matter detection experiments. We find that a significant region of the parameter space of these models is still accessible to these experiments. Amongst the models we analyze, the split family model provides solutions that can explain the observed deviation in anomalous magnetic moment of the muon. Furthermore, there is a notable region of the parameter space of each model which yields the desired relic abundance for neutralino dark matter. We also present the prediction of spin independent and spin dependent neutralino cross sections in these models and find that there is parameter space which can be probed at future experiments searching for dark matter. Our analysis serves as a motivation to continue the search for supersymmetry at various experimental fronts.

We perform a status analysis of popular supersymmetric models in light of recent constraints from experiments at the Large Hadron Collider (LHC). We find that a significant region of the parameter space of these models is still accessible to these experiments. Amongst the models we analyze, the split family model provides solutions that can explain the observed deviation in anomalous magnetic moment of the muon. Furthermore, there is a notable region of the parameter space of each model which yields the desired relic abundance for the neutralino. Our analysis serves as a motivation to continue the search for supersymmetry at various experimental fronts.

We explored the sparticle mass spectrum in light of the muon g -2 anomaly and the little hierarchy problem in a class of the gauge mediated supersymmetry breaking model. Here, the messenger fields transform in the adjoint representation of the Standard Model gauge symmetry. To avoid unacceptably light right-handed slepton masses, the Standard Model is supplemented by the additional U(1)(B-L) gauge symmetry. A nonzero U(1)(B-L) D term makes the right-handed slepton masses compatible with the current experimental bounds. We show that in the framework of Lambda(3) < 0 and mu < 0 the muon g -2 anomaly and the observed 125 GeV Higgs boson mass can be simultaneously accommodated. The slepton masses in this case are predicted to lie in the few hundred GeV range, which can be tested at the LHC. Despite the heavy colored sparticle spectrum, the little hierarchy problem in this model can be ameliorated, and the electroweak fine-tuning parameter can be as low as 10 or so.

We consider the SU(6) grand unified theory (GUT) model as an explanation for the diphoton final state excess, where the masses of all associated particles are linked with a new symmetry breaking scale. In this model, the diphoton final states arise due to loops involving three pairs of new vectorlike particles having the same quantum numbers as down-type quarks and lepton doublets. These new vectorlike fermions arc embedded alongside the standard model (SM) fermions into minimal anomaly-free representations of the SU(6) gauge symmetry. The SU(6) symmetry is broken to the standard model times U(1)(x) at the GUT scale, and masses for the vectorlike fermions arise at the TeV scale only after the residual U(1)(x) symmetry is broken. The vectorlike fermions do not acquire masses via breaking of the SM symmetry at the electroweak scale. The field which is responsible for the newly observed resonance belongs to the 6(H) representation. The dark matter arises from the SM singlet fermion residing in 6 and is of Majorana type. We explicitly demonstrate gauge coupling unification in this model, and also discuss the origin of neutrino masses. In addition to the diphoton final states, we make distinctive predictions for other final states which are likewise accessible to the ongoing LHC experimental effort.

We present a class of models in the framework of gauge mediation supersymmetry breaking where the messenger fields transform in the adjoint representation of the standard model gauge symmetry. To avoid unacceptably light right-handed sleptons in the spectrum we introduce a nonzero U(1)(B-L) D-term. This leads to an additional contribution to the soft supersymmetry breaking mass terms which makes the right-handed slepton masses compatible with the current experimental bounds. We show that in this framework the observed 125 GeV Higgs boson mass can be accommodated with the sleptons accessible at the LHC, while the squarks and gluinos lie in the multi-TeV range. We also discuss the issue of the fine-tuning and show that the desired relic dark matter abundance can also be accommodated.

We consider the diphoton resonance at the 13 TeV LHC in a consistent model with new scalars and vector-like fermions added to the Standard Model (SM), which can be constructed from orbifold grand unified theories and string models. The gauge coupling unification can be achieved, neutrino masses can be generated radiatively, and electroweak vacuum stability problem can be solved. To explain the diphoton resonance, we study a spin-0 particle, and discuss various associated final states.

We consider the diphoton resonance at the 13 TeV LHC in the context of SU(5) grand unification. A leading candidate to explain this resonance is a standard model singlet scalar decaying to a pair of photon by means of vector-like fermionic loops. We demonstrate the effect of the vector-like multiplets (5, 5 bar) and (10, 10 bar) on the evolution of the gauge couplings and perturbatively evaluate the weak scale values of the new couplings and masses run down from the unification scale. We use these masses and couplings to explain the diphoton resonance after considering the new dijet constraints. We show how to accommodate the larger decay width of the resonance particle, which seems to be preferred by the experimental data. In addition, we consider new couplings relating various components of (5, 5 bar) and (10, 10 bar) in the context of the orbifold GUTs, where the resonance scalar can be a part of the new vector-like lepton doublets. We also calculate the Higgs mass and proton decay rate to positron and neutral pion in the context of SU(5) grand unification, including effects of the new vector-like multiplets.

We explore the implications of t-b-tau (and b-tau) Yukawa coupling unification condition on the fundamental parameter space and sparticle spectroscopy in the minimal gauge mediated supersymmetry breaking (mGMSB) model. We find that this scenario prefers values of the CP-odd Higgs mass m_A > 1 TeV, with all colored sparticle masses above 3 TeV. These predictions will be hard to test at LHC13 but they may be testable at HE-LHC 33 TeV or a 100 TeV collider. Both t-b-tau and b-tau Yukawa coupling unifications prefer a relatively light gravitino with mass < 30 eV, which makes it a candidate hot dark matter particle. However, it cannot account for more than 15 % of the observed dark matter density.

We study a grand unified theories inspired supersymmetric model with nonuniversal gaugino masses that can explain the observed muon $g\ensuremath{-}2$ anomaly while simultaneously accommodating an enhancement or suppression in the $h\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ decay channel. In order to accommodate these observations and ${m}_{h}\ensuremath{\simeq}125$ to 126 GeV, the model requires a spectrum consisting of relatively light sleptons whereas the colored sparticles are heavy. The predicted stau mass range corresponding to ${R}_{\ensuremath{\gamma}\ensuremath{\gamma}}\ensuremath{\ge}1.1$ is $100\text{ }\text{ }\mathrm{GeV}\ensuremath{\lesssim}\phantom{\rule{0ex}{0ex}}{m}_{\stackrel{\texttildelow{}}{\ensuremath{\tau}}}\ensuremath{\lesssim}200\text{ }\text{ }\mathrm{GeV}$. The constraint on the slepton masses, particularly on the smuons, arising from considerations of muon $g\ensuremath{-}2$ is somewhat milder. The slepton masses in this case are predicted to lie in the few hundred GeV range. The colored sparticles turn out to be considerably heavier with ${m}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\gtrsim}4.5\text{ }\text{ }\mathrm{TeV}$ and ${m}_{{\stackrel{\texttildelow{}}{t}}_{1}}\ensuremath{\gtrsim}3.5\text{ }\text{ }\mathrm{TeV}$, which makes it challenging for these to be observed at the 14 TeV LHC.

We study a grand unified theories inspired supersymmetric model with nonuniversal gaugino masses that can explain the observed muon g - 2 anomaly while simultaneously accommodating an enhancement or suppression in the h -> gamma gamma decay channel. In order to accommodate these observations and m(h) similar or equal to 125 to 126 GeV, the model requires a spectrum consisting of relatively light sleptons whereas the colored sparticles are heavy. The predicted stau mass range corresponding to R-gamma gamma >= 1.1 is 100 GeV less than or similar to m (tau) over tilde less than or similar to 200 GeV. The constraint on the slepton masses, particularly on the smuons, arising from considerations of muon g - 2 is somewhat milder. The slepton masses in this case are predicted to lie in the few hundred GeV range. The colored sparticles turn out to be considerably heavier with m (g) over tilde greater than or similar to 4.5 TeV and m (t(1)) over tilde greater than or similar to 3.5 TeV, which makes it challenging for these to be observed at the 14 TeV LHC.

We study the neutralinos and sleptons in multilepton final states at the LHC in light of (g - 2)(mu) anomaly. We scan the minimal supersymmetric standard model parameters relevant to (g - 2)(mu) and focus on three distinct cases with different neutralino compositions. The explanation of (g - 2)(mu) excess at 2s range requires the smuon ((mu) over bar (1)) to be lighter than similar to 500(1000) GeV for tan beta = 10(50). Correspondingly the two lightest neutralinos, (chi) over bar (0)(1), (chi) over bar (0)(2), have to be lighter than similar to 300(650) GeV and 900 (1500) GeV, respectively. We explore the prospects of searching these light neutralinos and smuons at the LHC. The upcoming run of the LHC will be able to set 95% CL exclusion limit on M-(chi) over bar 20 (similar to 650 - 1300 GeV) and m((l) over bar) (similar to 670 - 775 GeV) with M-(chi) over bar 10 similar to 100 - 250 GeV at 3000 fb(-1) integrated luminosity in multilepton + is not an element of(T) channel.

We present a class of models in the framework of gauge mediation supersymmetry breaking where the standard model is supplemented by additional U(1) symmetry which acts only on the third generation fermions. The messenger fields carry a nontrivial U(1) charge and are vectorlike particles under this symmetry. This leads to additional contributions to the soft supersymmetry breaking mass terms for the third-generation squarks and sleptons. In this framework we show that the muon g - 2 anomaly, the observed 125 GeV Higgs boson mass and the detected relic dark matter abundance (gravitino in our case) can be simultaneously accommodated. The resolution of the muon g - 2 anomaly, in particular, yields the result that masses of squarks in the first two families, as well the gluino mass, should be less than or similar to 2.5 TeV, which will be tested at LHC14.

We present some R-parity conserving supersymmetric models which can accommodate the 3.5 keV X-ray line reported in recent spectral studies of the Perseus galaxy cluster and the Andromeda galaxy. Within the Minimal Supersymmetric Standard Model (MSSM) framework, the dark matter (DM) gravitino (or the axino) with mass of around 7 keV decays into a massless neutralino (bino) and a photon with lifetime ∼ 1028 sec. The massless bino contributes to the effective number of neutrino species N eff and future data will test this prediction. In the context of NMSSM, we first consider scenarios where the bino is massless and the singlino mass is around 7 keV. We also consider quasi-degenerate bino-singlino scenarios where the mass scale of DM particles are O(GeV) or larger. In such a scenario we require the mass gap to generate the 3.5 keV line. We comment on the possibility of a 7 keV singlino decaying via R parity violating couplings while all other neutralinos are heavy.