High Energy Physics Phenomenology

The one-loop contributions to the trilinear neutral gauge boson couplingsZZV??(V=γ,Z,Z??), parametrized in terms of oneCP-conservingfV5and oneCP-violatingfV4form factors, are calculated in models withCP-violating flavor changing neutral current couplings mediated by theZgauge boson and an extra neutral gauge bosonZ??. Analytical results are presented in terms of both Passarino-Veltman scalar functions and closed form functions. Constraints on the vector and axial couplings of theZgauge boson????gtuVZ????<0.0096and????gtcVZ????<0.011are obtained from the current experimental data on thet?�Zqdecays. It is found that in the case of theZZγ??vertex the only non-vanishing form factor isfγ5, which can be of the order of10??, whereas for theZZZ??vertex both form factorsfZ5andfZ4are non-vanishing and can be of the order of10??and10??, respectively. Our estimates forfγ5andfZ5are smaller than those predicted by the standard model, wherefZ4is absent up to the one loop level. We also estimate theZZZ????form factors arising from both diagonal and non-diagonalZ??couplings within a few extension models. It is found that in the diagonal casefZ??5is the only non-vanishing form factor and its real and imaginary parts can be of the order of10????10??and10????10??, respectively, with the dominant contributions arising from the light quarks and leptons. In the non-diagonal casefZ??5can be of the order of10??, whereasfZ??4can reach values as large as10????10??, with the largest contributions arising from theZ??tqcouplings.

We propose a 3+1 Higgs Doublet Model based on the?(27)family symmetry supplemented by several auxiliary cyclic symmetries leading to viable Yukawa textures for the Standard Model fermions, consistent with the observed pattern of fermion masses and mixings. The charged fermion mass hierarchy and the quark mixing pattern is generated by the spontaneous breaking of the discrete symmetries due to flavons that act as Froggatt-Nielsen fields. The tiny neutrino masses arise from a radiative seesaw mechanism at one loop level, thanks to a preservedZ(1)2discrete symmetry, which also leads to stable scalar and fermionic dark matter candidates. The leptonic sector features the predictive cobimaximal mixing pattern, consistent with the experimental data from neutrino oscillations. For the scenario of normal neutrino mass hierarchy, the model predicts an effective Majorana neutrino mass parameter in the range3~meV??mββ??18meV, which is within the declared range of sensitivity of modern experiments. The model predicts Flavour Changing Neutral Currents which constrain the model, for instance Kaon mixing andμ?�enuclear conversion processes, the latter which are found to be within the reach of the forthcoming experiments.

The objective of this study is to correlate the scaling factor of the Standard Model (SM) like Higgs boson and the cross section ratio of the processe+e???�hhff¯¯¯wheref?�t, normalized to SM predictions in the type I of the Two Higgs Doublet Model. All calculations have been performed ats??=500GeV and1?�tanβ??0for massesmH=mA=mH±=300GeVandmH=300GeV,mA=mH±=500GeV. The working scenario is by taking without alignment limit, that issβ?��?=0.98andsβ?��?=0.99,0.995, which gives the enhancement in the cross section, particularly a few times greater than the predictions of the SM due to resonant-impacts of the additional heavy neutral Higgs bosons. This shows that enhancement in cross section occurs on leaving the alignment i.e.,sβ?��?=1, at which all the higgs that couple to vector bosons and fermions have the same values as in SM at tree level. A large value of enhancement factor is obtained atsβ?��?=0.98compared tosβ?��?=0.99,0.995. Furthermore, the decrease in the enhancement factor is observed for the case whenmH=300GeV,mA=mH±=500GeV. The behavior of the scaling factor withtanβis also studied, which shows that for large values oftanβ, the scaling factor becomes equal tosβ?��?. Finally a convincing correlation is achieved by taking into account, the experimental and theoretical constraints e.g, perturbative unitarity, vacuum stability and electroweak oblique parameters.

A novel mechanism of boosting dark matter by cosmic neutrinos is proposed. The new mechanism is so significant that the arriving flux of dark matter in the mass window1 keV??mDM?? MeVon Earth can be enhanced by two to four orders of magnitude compared to one only by cosmic electrons. Thereby we firstly derive conservative but still stringent bounds and future sensitivity limits for such cosmic-neutrino-boosted dark matter (νBDM) from advanced underground experiments such as Borexino, PandaX, XENON1T, and JUNO.

We reexamine the cosmological constant problem in a finite temperature setup and propose an intriguing possibility of carrying out perturbative analysis by employing a renormalization scheme in which the renormalized Higgs mass taken to be on the order of the CMB temperature. Finite-temperature-induced complexification of the effective potential is observed and its interpretation is given. It is shown that the cosmological constant problem is avoided.

We will present the latest developments in CutLang, the runtime interpreter of a recently-developed analysis description language (ADL) for collider data analysis. ADL is a domain-specific, declarative language that describes the contents of an analysis in a standard and unambiguous way, independent of any computing framework. In ADL, analyses are written in human-readable plain text files, separating object, variable and event selection definitions in blocks, with a syntax that includes mathematical and logical operations, comparison and optimisation operators, reducers, four-vector algebra and commonly used functions. Adopting ADLs would bring numerous benefits to the LHC experimental and phenomenological communities, ranging from analysis preservation beyond the lifetimes of experiments or analysis software to facilitating the abstraction, design, visualization, validation, combination, reproduction, interpretation and overall communication of the analysis contents. Since their initial release, ADL and CutLang have been used for implementing and running numerous LHC analyses. In this process, the original syntax from CutLang v1 has been modified for better ADL compatibility, and the interpreter has been adapted to work with that syntax, resulting in the current release v2. Furthermore, CutLang has been enhanced to handle object combinatorics, to include tables and weights, to save events at any analysis stage, to benefit from multi-core/multi-CPU hardware among other improvements. In this contribution, these and other enhancements are discussed in details. In addition, real life examples from LHC analyses are presented together with a user manual.

Correlators of Wilson-line operators in non-abelian gauge theories are known to exponentiate, and their logarithms can be organised in terms of collections of Feynman diagrams called webs. In [1] we introduced the concept of Cweb, or correlator web, which is a set of skeleton diagrams built with connected gluon correlators, and we computed the mixing matrices for all Cwebs connecting four or five Wilson lines at four loops. Here we complete the evaluation of four-loop mixing matrices, presenting the results for all Cwebs connecting two and three Wilson lines. We observe that the conjuctured column sum rule is obeyed by all the mixing matrices that appear at four-loops. We also show how low-dimensional mixing matrices can be uniquely determined from their known combinatorial properties, and provide some all-order results for selected classes of mixing matrices. Our results complete the required colour building blocks for the calculation of the soft anomalous dimension matrix at four-loop order.

We study the behaviour of the?c1(3872), also known asX(3872), in dense nuclear matter. We begin from a picture in vacuum of theX(3872)as a purely molecular(DD¯???�c.c.)state, generated as a bound state from a heavy-quark symmetry leading-order interaction between the charmed mesons, and analyze theDD¯??scatteringT??matrix (TDD¯??) inside of the medium. Next, we consider also mixed-molecular scenarios and, in all cases, we determine the correspondingX(3872)spectral function and theDD¯??amplitude, with the mesons embedded in the dense environment. We find important nuclear corrections forTDD¯??and the pole position of the resonance, and discuss the dependence of these results on theDD¯??molecular component in theX(3872)wave-function. These predictions could be tested in the finite-density regime that can be accessed in the future CBM and PANDA experiments at FAIR.

We present a new paradigm of dark matter freeze-out, where the annihilation of dark matter particles is catalyzed. We discuss in detail the regime that the depletion of dark matter proceeds via2???A??and3A?????processes, in which?andA??denote dark matter and the catalyst respectively. In this regime, the dark matter number density is depleted polynomially rather than exponentially (Boltzmann suppression) as in classic WIMPs and SIMPs. The paradigm applies for a secluded weakly interacting dark sector with a dark matter in theMeV-TeVmass range. The catalyzed annihilation paradigm is compatible with CMB and BBN constraints, with enhanced indirect detection signals.

We consider a minimal type Ib seesaw model where the effective neutrino mass operator involves two different Higgs doublets, and the two right-handed neutrinos form a heavy Dirac mass. We propose a minimal dark matter extension of this model, in which the Dirac heavy neutrino is coupled to a dark Dirac fermion and a dark complex scalar field, both charged under a discreteZ2symmetry, where the lighter of the two is a dark matter candidate. Focussing on the fermionic dark matter case, we explore the parameter space of the seesaw Yukawa couplings, the neutrino portal couplings and dark scalar to dark fermion mass ratio, where correct dark matter relic abundance can be produced by the freeze-in mechanism. By considering the mixing between between the standard model neutrinos and the heavy neutrino, we build a connection between the dark matter production and current laboratory experiments ranging from collider to lepton flavour violating experiments. For a GeV mass heavy neutrino, the parameters related to dark matter production are constrained by the experimental results directly and can be further tested by future experiments such as SHiP.