118835200
THE CHIRAL COLOR SYMMETRY OF QUARKS AND G′-BOSON CONTRIBUTIONS TO CHARGE ASYMMETRY IN $t \bar t$-PRODUCTION AT THE LHC AND TEVATRON
The contributions of G′-boson predicted by the chiral color symmetry of quarks to the charge asymmetry in -production at the LHC and to the forward–backward asymmetry in -production at the Tevatron are calculated and analyzed in dependence on two free parameters of the model, the G′ mass mG′ and mixing angle θG. The mG′ - θG regions of 1 σ consistency with the CMS data on the cross-section and on the charge asymmetry are found and compared with those resulted from the CDF data on the cross-section and on the forward–backward asymmetry of -production at the Tevatron with account of the current SM predictions for .
15376747
ON A POSSIBLE MANIFESTATION OF THE FOUR-COLOR SYMMETRY Z' BOSON IN μ+μ- EVENTS AT THE LHC
The cross section of the μ+μ- pair production in pp-collisions at the LHC is calculated with account of the Z' boson induced by the minimal four-color quark–lepton symmetry (MQLS). The μ+μ- invariant mass spectrum with account of the MQLS Z' boson is analyzed in dependence on the Z' mass. The mass region for the MQLS Z' boson observable at the LHC is found in dependence on the significance and on the integrated luminosity.
118447115
COLORED SCALAR PARTICLES PRODUCTION IN pp-COLLISIONS AND POSSIBLE MASS LIMITS FOR SCALAR GLUONS FROM FUTURE LHC DATA
Cross sections of the colored scalar particle production in pp-collisions are calculated and differential and total cross sections of the corresponding parton subprocesses are obtained. The total cross section of scalar gluon production in pp-collisions at the LHC is estimated and the dominant decays of scalar gluons are discussed. The production cross section of scalar gluons F with masses mF ≲ 1300 GeV is shown to be sufficient for the effective production of these particles at the LHC.
122714200
Limits on the scalar-leptoquark and scalar-gluon masses from the parameters S, T, and U in the minimal model based on four-color symmetry
The contributions to the parameters S, T, and U of radiative corrections from the doublets of scalar leptoquarks and scalar gluons are analyzed within the minimal model based on four-color symmetry of the Pati-Salam type. It is shown that current experimental data on the parameters S, T, and U admit the existence of relatively light scalar leptoquarks and scalar gluons (of mass lower than 1 TeV), the best fit to experimental data being attained at mass values not greater than 400 GeV. In particular, the existence of scalar leptoquarks of mass below 300 GeV is found to be compatible with data on the parameters S, T, and U at χ2 < 3.1 (3.2) for mH = 115 (300) GeV as against χSM2 = 3.5 (5.0) in the Standard Model. The mass of the lightest scalar gluon is then predicted to be less than 850 (720) GeV. It is emphasized that the aforementioned doublets of scalar leptoquarks and scalar gluons can play a significant role in processes involving a t quark at LHC.
17592505
Bounds on Scalar Leptoquark Masses from S T U in the Minimal Model With the Four Color Symmetry
The contributions into radiative correction S T U parameters from the scalar leptoquarks are considered in frame of the minimal model with the four color gauge symmetry Taking the current exper imental data on S T U into account the bounds on the scalar lep toquark masses are obtained and discussed In particular it is shown that the current experimental data on S T U allow the existence of relatively light scalar leptoquark with electric charge The search for a new physics beyond the Standard Model SM is now one of the aims of the high energy physics It is interesting to know what kind of the new physics can manifest itself as the energy of the colliding particles increase What are the possible manifestations of such new physics at attainable energies One of the possible variants of the new physics beyond the SM can turn out to be the variant induced by the possible four color symmetry between quarks and leptons The main feature of the four color gauge symmetry is the prediction of the vector leptoquarks with the masses of about the mass scale Mc of the four color symmetry breaking In the models induced by the grand uni cation ideas the four color symmetry can manifest itself as an intermediate E mail asmirnov univ uniyar ac ru symmetry with mass scaleMc expected to be usually very high For instance in SO model it is of about Mc GeV but it can be essentially lowered up to Mc GeV by appropriate scheme of the symmetry breaking In the models regarding the four color symmetry as a primary symmetry the lower limit on the mass scale Mc is determined mainly by the low energy experimental data and it can be essentially lower for example of about TeV or about TeV or slightly less or even of about TeV The four color symmetry can manifest itself not only by the vector lep toquark physics but also due to the scalar leptoquarks Some of the scalar leptoquarks should have SU doublet structure and hence can mani fest themselves in the oblique radiative corrections in particular a ecting the S T U parameters of Peskin and Takeuchi Taking into account the rather stringent current experimental limits on S T U it is interesting to know what bounds on the scalar leptoquark masses can be extracted from the current experimental data on S T U For this purpose it is interesting to know the e ect of the scalar leptoquarks on S T U in some simple gauge model predicting these particles In this talk I would like to consider the contributions into S T U pa rameters from the scalar leptoquarks in frame of a minimal model with the four color symmetry in comparison with the current experimental data on S T U and to discuss the bounds on scalar leptoquark masses which can be extracted in this model from these data The minimal quark lepton symmetry model MQLS model to be used here as a minimal extension of the SM containing the four color gauge symmetry is based on the gage group SUV SUL UR The fermion sector of the model contains only the known fermions quarks and leptons whereas the gauge sector predicts the new gauge particles vector leptoquarks V with electric charge and an extra neutral Z boson The scalar sector of the model contains in general the four multiplets a a a transforming according to the representations of the SUV SUL UR group and having the VEV s respectively the content of the multiplets and notations can be found in more detail in Refs As regards the S T U parameters the most intersting of these multiplets is the muliplet which has been introduced to split the masses of quarks and leptons This multiplet contains fteen doublets which can be arranged into two scalar leptoquark doublets S a and S a with the SM hy percharge Y SM and respectively eight scalar gluon doublets Fja j with Y SM and the doublet a which in admixture with a gives the SM doublet SM with SM VEV p p GF GeV and an additional scalar doublet In addition to the scalar leptoquark doublets S a of the multiplet the multiplets and contain the singlet scalar leotoquarks S and S with electric charge which give in admixture with S S the Goldstone mode S and three mass eigenstate leptoqurk elds S S S As a result in the unitary gauge we obtain in general ve scalar leptoquarks S S with electric charge and respectively and Sk k with electric charge The resulting contributions into S T U from leptoquarks can be pre sented in the form S LQ nc X X k jC k j Y SM ln m m k X
17736206
BOUNDS ON SCALAR LEPTOQUARK MASSES FROM S, T, U PARAMETERS IN THE MINIMAL FOUR-COLOR QUARK-LEPTON SYMMETRY MODEL
Abstract The contributions into radiative correction parameters S , T , U from the scalar leptoquarks are calculated in the minimal gauge model with the four-color quark-lepton symmetry. It is shown that the contributions into T and U from the scalar leptoquark doublets are not positive definite. Using the current experimental data on S , T , U the bounds on the scalar leptoquark masses are obtained. In particular, the existence of the relatively light scalar leptoquark with electric charge 2/3 is shown to be compatible with the current experimental data on S , T , U .
118663090
Neutrino Propagation in Matter
We describe the effects of neutrino propagation in the matter of the Earth relevant to experiments with atmospheric and accelerator neutrinos and aimed at the determination of the neutrino mass hierarchy and CP violation. These include (i) the resonance enhancement of neutrino oscillations in matter with constant or nearly constant density, (ii) adiabatic conversion in matter with slowly changing density, (iii) parametric enhancement of oscillations in a multilayer medium, and (iv) oscillations in thin layers of matter. We present the results of semianalytic descriptions of flavor transitions for the cases of small density perturbations, in the limit of large densities and for small density widths. Neutrino oscillograms of the Earth and their structure after determination of the 1–3 mixing are described. A possibility to identify the neutrino mass hierarchy with the atmospheric neutrinos and multimegaton scale detectors having low energy thresholds is explored. The potential of future accelerator experiments to establish the hierarchy is outlined.
7188792
Neutrinos and structure of the intermediate mass scale
Abstract Neutrino data lead via the see-saw mechanism to masses of the right handed neutrinos at the intermediate mass scale. A simple formalism is suggested which incorporates the quark-lepton symmetry and allows one to find properties of the intermediate scale (masses and mixing) from neutrino data. The averaged mass scale and the mass hierarchy parameter are introduced and fixed by the data. They determine natural ranges of masses and mixing at the intermediate scale. In particular, a scenario which includes the MSW solution of the solar neutrino problem and tau neutrino as the hot component of the dark matter in the Universe leads to M2 = (2–4) × 1010 GeV and M3 = (4–8) × 1012 GeV in agreement with the linear mass hierarchy. Strong deviations from these natural ranges imply fine tuning of parameters or/and certain symmetry of the Majorana mass matrix of the right handed neutrinos.
18429197
Solar Neutrinos and Lepton Mixing
With latest experimental data the solar neutrino problem enters new phase when crucial aspects of the problem can be formulated in an essentially (solar) model independent way. Original neutrino fluxes can be considered as free parameters to be found from the solar neutrino experiments. Resonance flavour conversion gives the best fit of all experimental results. Already existing data allow one to constraint both the neutrino parameters and the original neutrino fluxes. The reconciliation of the solution of the solar neutrino problem with other neutrino mass hints (atmospheric neutrino problem, hot dark matter etc.) may require the existence of new very light singlet fermion. Supersymmetry can provide a framework within which the desired properties of such a light fermion follow naturally. The existence of the fermion can be related to axion physics, mechanism of $\mu$-term generation etc..
14569030
NEUTRINOLESS DOUBLE BETA DECAY AND THE SOLAR NEUTRINO PROBLEM
Abstract The MSW or vacuum oscillation solution of the solar neutrino problem can be reconciled with the possible existence of the ( ββ ) 0 ν decay with a half-life corresponding to an effective Majorana mass of the electron neutrino | m ee | ≅ (0.1−1.0) eV. The phenomenological consequences of such a possibility are analyzed and the implications for the mechanisms of neutrino mass generation are considered.
119725964
Variations of solar neutrino signals and resonant conversion.