Lightest CP Research Articles

Light hyperon polarization and CP test at BESIII

Hyperon is an ideal probe to study the QCD in the region of non-perturbative to perturbative. Using 1.31 × 109 J/ψ and 448.1 × 106 ψ(3686) events, the hyperon anti-hyperon pair production are well studied. The hyperon polarization and its decay parameter have been measured in high precision through their quantum entangle system. By comparing the decay parameters in hyperon and anti-hyperon decays, the CP conservation observables has been measured which is important to test the Standard Model and search for New Physics.

Hadronic currents and form factors in three-body semileptonic tau decays

Three-body semileptonic tau -decays offer a path to understand the properties of light hadronic systems and CP symmetry violations through searches for electric dipole moments. In studies of electro-weak physics, the hadronic part of the final states has traditionally been described using the language of form factors. Spectroscopic information, resolved in terms of orbital angular momentum quantum-numbers, is best being derived from an explicit decomposition of the hadronic current in the orbital angular momentum basis. Motivated by the upcoming large data samples from mathrm {B} factories, we present the full description of the hadronic currents decomposed into quantum numbers of the hadronic final state using the isobar picture. We present formulas for orbital angular momenta up to three and apply the rules derived from hadron spectroscopy to formulate the decay chain of hadronic three-body systems of arbitrary mass. We also translate this formalism to the language of form factors and thereby correct insufficiencies found in previous analyses of three-body hadronic final states.

Mixed hidden sector-visible sector dark matter and observation of aCPodd Higgs boson at HL-LHC and HE-LHC

It is very likely that similar to the case of visible matter, dark matter too is composed of more than one stable component. In this work we investigate a two-component dark matter with one component from the visible sector and the other from the hidden sector. Specifically we consider a $U(1)_X$ hidden sector extension of MSSM/SUGRA where we allow for kinetic and Stueckelberg mass mixing between the two abelian $U(1)'s$, i.e., $U(1)_X$ and $U(1)_Y$. We further assume that the hidden sector has chiral matter which leads to a Dirac fermion as a candidate for dark matter. The lightest neutralino in the visible sector and the Dirac fermion in the hidden sector then constitute the two components of dark matter. We investigate in particular MSSM/SUGRA models with radiative breaking occurring on the hyperbolic branch where the Higgs mixing parameter $\mu$ is small (order the electroweak scale) which leads to a lightest neutralino being dominantly a higgsino. While dark matter constituted only of higgsinos is significantly constrained by data on dark matter relic density and by limits on spin independent proton-DM scattering cross section, consistency with data can be achieved if only a fraction of the dark matter relic density is constituted of higgsinos with the rest coming from the hidden sector. An aspect of the proposed model is the prediction of a relatively light CP odd Higgs $A$ (as well as a CP even $H$ and a charged Higgs $H^{\pm}$) which is observable at HL-LHC and HE-LHC. We perform a detailed collider analysis search for the CP odd Higgs using boosted decision trees in $\tau_h\tau_h$ final states and compare the discovery potential at HL-LHC and HE-LHC. We show that while several of the points among our benchmarks may be observable at HL-LHC, all of them are visible at HE-LHC with much lower integrated luminosities thus reducing significantly the run time for discovery.

Uncertainties in the lightest CP even Higgs boson mass prediction in the minimal supersymmetric standard model: fixed order versus effective field theory prediction

We quantify and examine the uncertainties in predictions of the lightest CP even Higgs boson pole mass M_h in the Minimal Supersymmetric Standard Model ({text {MSSM}}), utilising current spectrum generators and including some three-loop corrections. There are two broadly different approximations being used: effective field theory (EFT) where an effective Standard Model (text {SM}) is used below a supersymmetric mass scale, and a fixed order calculation, where the {text {MSSM}} is matched to text {QCD}times text {QED} at the electroweak scale. The uncertainties on the M_h prediction in each approach are broken down into logarithmic and finite pieces. The inferred values of the stop mass parameters are sensitively dependent upon the precision of the prediction for M_h. The fixed order calculation appears to be more accurate below a supersymmetry (SUSY) mass scale of M_Sapprox 1.2~text {TeV}, whereas above this scale, the EFT calculation is more accurate. We also revisit the range of the lightest stop mass across fine-tuned parameter space that has an appropriate stable vacuum and is compatible with the lightest CP even Higgs boson h being identified with the one discovered at the ATLAS and CMS experiments in 2012; we achieve a maximum value of sim 10^{11} GeV.

The quantitative models for broiler chicken response to monochromatic, combined, and mixed light-emitting diode light: A meta-analysis.

Although many experiments have been conducted to clarify the response of broiler chickens to light-emitting diode (LED) light, those published results do not provide a solid scientific basis for quantifying the response of broiler chickens. This study used a meta-analysis to establish light spectral models of broiler chickens. The results indicated that 455 to 495nm blue LED light produced the greatest positive response in body weight by 10.66% (BW; P < 0.001) and 515 to 560nm green LED light increased BW by 6.27% (P < 0.001) when compared with white light. Regression showed that the wavelength (455 to 660nm) was negatively related to BW change of birds, with a decrease of about 4.9% BW for each 100nm increase in wavelength (P = 0.002). Further analysis suggested that a combination of the two beneficial light sources caused a synergistic effect. BW was further increased in birds transferred either from green LED light to blue LED light (17.23%; P < 0.001) or from blue LED light to green LED light (17.52%; P < 0.001). Moreover, birds raised with a mixture of green and blue LED light showed a greater BW promotion (10.66%; P < 0.001) than those raised with green LED light (6.27%). A subgroup analysis indicated that BW response to monochromatic LED light was significant regardless of the genetic strain, sex, control light sources, light intensity and regime of LED light, environmental temperature, and dietary ME and CP (P > 0.05). However, there was an interaction between the FCR response to monochromatic LED light with those covariant factors (P < 0.05). Additionally, green and yellow LED light played a role in affecting the meat color, quality, and nutrition of broiler chickens. The results indicate that the optimal ratio of green × blue of mixed LED light or shift to green-blue of combined LED light may produce the optimized production performance, whereas the optimal ratio of green/yellow of mixed or combined LED light may result in the optimized meat quality.

Higgs mass from neutrino-messenger mixing

The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, At, relaxing these constraints. The detailed survey of these models [1, 2] so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ∼1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.

Post-Higgs THDM scenarios associated with the new diphoton resonance data

The CP -even and CP -odd scalar states of the two-Higgs-doublet model (THDM) and the Higgs sector of theMinimal Supersymmetric StandardModel (MSSM), with properties which could lead to the 750 GeV excess in the γγ invariant mass distribution, are studied. It is shown that THDM and MSSM are viable in explaining the observed excess without additional assumptions only when the alignment and decoupling limits break down. If the origin of the excess is not in a Higgs sector, regions of the MSSM parameter space are separated where the lightest CP -even Higgs boson is identical to the Standard Model scalar.

The Upper Bound on the Lightest CP Even Higgs Mass in the MSSM, NMSSM and ESSM

Recently a Higgs like particle is reported to be discovered at CMS and ATLAS experiments at CERN LHC with a mass of about 125 GeV. The aim of this paper is to study the theoretical upper bound of lightest CP even Higgs mass in MSSM, NMSSM and ESSM. Although at this moment it is not possible to conclude whether the observed Higgs like particle is Standard Model Higgs or Supersymmetric one, yet the present paper comes to the conclusion that it is possible to accommodate ~125 GeV Higgs mass within MSSM, NMSSM and ESSM.

New insights in the electroweak phase transition in the NMSSM

We perform a detailed semi-analytical analysis of the electroweak phase transition (EWPT) property in NMSSM, which serves as a good benchmark model in which the 126 GeV Higgs mixes with a singlet. In this case, a strongly first order electroweak phase transition (SFOEWPT) is achieved by the tree-level effects and the phase transition strength $\gamma_c$ is determined by the vacua energy gap at $T=0$. We make an anatomy of the energy gap at both tree-level and loop-level and extract out a dimensionless phase transition parameter $R_\kappa \equiv 4 \kappa v_s / A_\kappa$, which can replace $A_\kappa$ in the parameterization and affect the light CP odd and even Higgs spectra. We find that SFOEWPT only occurs in $R_\kappa \sim -1$ and positive $R_\kappa \lesssim \mathcal{O}(10)$, which in the non-PQ limit case would prefer either a relatively light CP odd or CP even Higgs boson $\sim (60, 100)$ GeV, therefore serves as a smoking gun signal and requires new search strategies at the LHC.

Higher order corrections and unification in the minimal supersymmetric standard model: SOFTSUSY3.5

We explore the effects of three-loop minimal supersymmetric standard model renormalisation group equation terms and some leading two-loop threshold corrections on gauge and Yukawa unification: each being one loop higher order than current public spectrum calculators. We also explore the effect of the higher order terms (often 2–3 GeV) on the lightest CP even Higgs mass prediction. We illustrate our results in the constrained minimal supersymmetric standard model. Neglecting threshold corrections at the grand unified scale, the discrepancy between the unification scale αs and the other two unified gauge couplings changes by 0.1% due to the higher order corrections and the difference between unification scale bottom-tau Yukawa couplings neglecting unification scale threshold corrections changes by up to 1%. The difference between unification scale bottom and top Yukawa couplings changes by a few percent. Differences due to the higher order corrections also give an estimate of the size of theoretical uncertainties in the minimal supersymmetric standard model spectrum. We use these to provide estimates of theoretical uncertainties in predictions of the dark matter relic density (which can be of order one due to its strong dependence on sparticle masses) and the LHC sparticle production cross-section (often around 30%). The additional higher order corrections have been incorporated into SOFTSUSY, and we provide details on how to compile and use the program. We also provide a summary of the approximations used in the higher order corrections. Program SummaryNature of problem: Calculating supersymmetric particle spectrum and mixing parameters in the minimal supersymmetric standard model. The solution to the renormalisation group equations must be consistent with boundary conditions on supersymmetry breaking parameters, as well as the weak-scale boundary condition on gauge couplings, Yukawa couplings and the Higgs potential parameters.Program title:SOFTSUSYCatalogue identifier: ADPM_v5_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADPM_v5_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 240528No. of bytes in distributed program, including test data, etc.: 2597933Distribution format: tar.gzProgramming language: C++, Fortran.Computer: Personal computer.Operating system: Tested on Linux 3.4.6.Word size: 64 bits.Classification: 11.1, 11.6.External routines: At least GiNaC1.3.5 [1] and CLN1.3.1 (both freely obtainable from http://www.ginac.de).Does the new version supersede the previous version?: YesCatalogue identifier of previous version: ADPM_v4_0Journal reference of previous version: Comput. Phys. Comm. 185 (2014) 2322Solution method: Nested iterative algorithm.Reasons for new version: Extension to include additional two and three-loop terms.Summary of revisions: All quantities in the minimal supersymmetric standard model are extended to have three-loop renormalisation group equations (including 3-family mixing) in the limit of real parameters and some leading two-loop threshold corrections are incorporated to the third family Yukawa couplings and the strong gauge coupling.Restrictions:SOFTSUSY will provide a solution only in the perturbative regime and it assumes that all couplings of the model are real (i.e. CP-conserving). If the parameter point under investigation is non-physical for some reason (for example because the electroweak potential does not have an acceptable minimum), SOFTSUSY returns an error message. The higher order corrections included are for the real R-parity conserving minimal supersymmetric standard model (MSSM) only.Running time: A minute per parameter point. The tests provided with the package only take a few seconds to run.

Top quark and Higgs boson masses in supersymmetric models

We study the implications for bounds on the top quark pole mass m t in models with low scale supersymmetry following the discovery of the Standard Model-like Higgs boson. In the minimal supersymmetric standard model, we find that m t ≥ 164 GeV, if the light CP even Higgs boson mass m h = 125 ± 2 GeV. We also explore the top quark and Higgs boson masses in two classes of supersymmetric SO(10) models with t-b-τ Yukawa coupling unification at M GUT. In particular, assuming SO(10) compatible non-universal gaugino masses, setting m h = 125 GeV and requiring 5% or better Yukawa unification, we obtain the result 172 GeV ≤ m t ≤ 175 GeV. Conversely, demanding 5% or better t-b-τ Yukawa unification and setting m t = 173.2 GeV, the Higgs boson mass is predicted to lie in the range 122 GeV ≤ m h ≤ 126 GeV.

Higgs mass in the MSSM with flavor mixing soft terms

The Minimal Supersymmetric Standard Model assumes scalar masses universality as a simplification to avoid undesired flavor changing neutral currents (FCNC). In this work, we consider that the trilinear SUSY soft–terms have a hierarchical structure of flavor mixing within generations, leading to a non–degeneration on sfermion masses preserving FCNC under control. We consider this kind of mixing for the u–type squark mass matrix and analyze the consequences on the radiative corrections to the Higgs mass. We work under the consideration of mmaxh benchmark scenario, in which the parameter space is set to maximize the radiative contributions to the Higgs mass. Based on recent experimental results on possible Higgs signals, we calculate the mass of the neutral light CP–even Higgs taking into account flavor mixing contributions.

A little more gauge mediation and the light Higgs mass

We consider minimal models of gauge mediated supersymmetry breaking with an extra U(1) factor in addition to the Standard Model gauge group. A U(1) charged, Standard Model singlet is assumed to be present which allows for an additional NMSSM like coupling, λHuHdS. The U(1) is assumed to be flavour universal. Anomaly cancellation in the MSSM sector requires additional coloured degrees of freedom. The S field can get a large vacuum expectation value along with consistent electroweak symmetry breaking. It is shown that the lightest CP even Higgs boson can attain mass of the order of 125 GeV.

Higgs boson Mass in GMSB with Messenger–Matter mixing

A Higgs-like particle with mass of order 125 GeV has been observed by both ATLAS and CMS experiments. This Higgs mass causes sparticle masses in the several to multi-TeV range in the simple version of minimal GMSB models. We consider the effects of messenger–matter mixing on the lightest CP–even Higgs boson mass in gauge–mediated supersymmetry breaking models. We find with such mixings a 125 GeV Higgs boson can be naturally obtained even with a sub–TeV SUSY spectrum, and when the gravitino has a cosmologically preferred sub–keV mass. In addition, when these models are embedded into a grand unification framework with a U(1) flavor symmetry they explain the fermion mass hierarchy and generate naturally large neutrino mixing angles accompanied with small quark mixing angles. While SUSY mediated flavor changing processes are sufficiently suppressed in such an embedding, it can resolve the apparent discrepancy in the CP asymmetry parameters sin2β and ϵK, and it predicts an observable μ→eγ decay rate.

Supersymmetric next-to-next-to-leading order corrections to Higgs boson production in gluon fusion

We compute the total cross section for the production of a light CP even Higgs boson within the framework of supersymmetric QCD up to next-to-next-to-leading order. Technical subtleties in connection to the evaluation of three-loop Feynman integrals with many mass scales are discussed in detail and explicit results for the counterterms of the evanescent couplings are provided. The new results are applied to several phenomenological scenarios which are in accordance with the recent discovery at the LHC. In a large part of the still allowed parameter space the $K$ factor of the supersymmetric theory is close to the one of the Standard Model. However, for the case where one of the top squarks is light, a deviation of more than 5% in the next-to-next-to-leading order prediction of the cross section can be observed where at the same time the predicted Higgs boson mass has a value of about 125 GeV.

γγ→ϕiϕjprocesses in the type-III two-Higgs-doublet model

We discuss the implications of assuming a four-zero Yukawa texture and a general Higgs potential for the production of neutral Higgs boson pairs at \gamma \gamma colliders through the \gamma \gamma \to \phi_i\phi_j (\phi_i = h, H, A) reaction within the context of the two Higgs doublet model type III. Exact analytical expressions for the \gamma \gamma \to \phi_i\phi_j reaction are presented. The use of a nonlinear R_\xi-gauge, which considerably simplifies the loop calculations and renders compact analytical expressions, is stressed. We show that these processes are very sensitive to a general structure of the Higgs potential that impact the triple and quartic couplings of the scalar sector. We present results for scenarios of the parameters of the model that are still consistent with current experimental constraints. It is found that the cross sections for the \gamma \gamma \to \phi_i\phi_j processes can be up to two orders of magnitude larger than those gotten in 2HDM type I and type II. The possibility of a light CP--scalar is also studied.

Search of Light New Physics at BABAR

In some extensions to the Standard Model such as the non-minimal symmetric model (nMSSM), a light CP -odd Higgs boson (A0) can arise, where light here means less than twice the mass of the B meson. The light Higgs boson can be produced via Υ (nS) → γA0, where n = 2, 3. BABAR has searched for evidence for the processes A0 → μ+μ−, A0 → τ+τ−, and, more recently, A0 → hadrons. First the BABAR experiment will be briefly described, then the results from searches of the (charged) leptonic decays of A0 will be highlighted. Afterward, the main result of the search for hadronic decays of the A0 will be presented in detail.

Light MSSM Higgs boson mass to three-loop accuracy

The light CP even Higgs boson mass, Mh, is calculated to three-loop accuracy within the Minimal Supersymmetric Standard Model (MSSM). The result is expressed in terms of DRbar parameters and implemented in the computer program H3m. The calculation is based on the proper approximations and their combination in various regions of the parameter space. The three-loop effects to Mh are typically of the order of a few hundred MeV and opposite in sign to the two-loop corrections. The remaining theory uncertainty due to higher order perturbative corrections is estimated to be less than 1 GeV.

Constraints on the mass spectrum of fourth generation fermions and Higgs bosons

We reanalyze constraints on the mass spectrum of the chiral fourth generation fermions and the Higgs bosons for the standard model (SM4) and the two Higgs doublet model (THDM). We find that the Higgs mass in the SM4 should be larger than roughly the fourth generation up-type quark mass, while the light CP even Higgs mass in the THDM can be smaller. Various mass spectra of the fourth generation fermions and the Higgs bosons are allowed. The phenomenology of the fourth generation models is still rich.

Higgs phenomenology of scalar sequestering

The light Higgs mass in the MSSM is highly constrained and is predicted to be close to M_Z which causes a tension between the LEP II Higgs mass bound 114 GeV and the natural electroweak symmetry breaking in the MSSM. The usual way to increase the light CP even Higgs mass was to increase the quartic coupling of the up type Higgs. We point out that the light Higgs mass can be increased by reducing the off-diagonal term in the mass matrix when tan beta is moderate, which is about 5 to 10. As a result no mixing and/or a Higgs mixing angle of the opposite sign arises and the branching ratio of Higgs decay is drastically changed. This is possible in scalar sequestering scenario in which mu parameter can be large independently of the electroweak symmetry breaking. We also discuss the same effect in the BMSSM.