D. P. Roy

We study the naturalness of electroweak symmetry breaking and baryogenesis in the next-to-minimal supersymmetric standard model (NMSSM). Our study is motivated by the recent LEP bounds on the Higgs boson mass which severely constrains the low \tan\beta region of the minimal supersymmetric standard model (MSSM). We show that the low \tan \beta region of the NMSSM is clearly favoured over the MSSM with regard to the physical Higgs boson mass, fine-tuning, and electroweak baryogenesis.

We consider the gauging of $L_\mu - L_\tau$ as an explanation of a possibly large muon anomalous magnetic moment. We then show how neutrino masses with bimaximal mixing may be obtained in this framework. We study the novel phenomenology of the associated gauge boson in the context of present and future high-energy collider experiments.

Textile dyes are the burgeoning environmental contaminants across the world. They might be directly disposed of from textile industries into the aquatic bodies, which act as the direct source for the entire ecosystem, ultimately impacting the human beings. Hence, it is essential to dissect the potential adverse outcomes of textile dye exposure on aquatic plants, aquatic fauna, terrestrial entities, and humans. Analysis of appropriate literature has revealed that textile dye effluents could affect the aquatic biota by disrupting their growth and reproduction. Various aquatic organisms are targeted by textile dye effluents. In such organisms, these chemicals affect their development, behavior, and induce oxidative stress. General populations of humans are exposed to textile dyes via the food chain and drinking contaminated water. In humans, textile dyes are biotransformed into electrophilic intermediates and aromatic amines by the enzymes of the cytochrome family. Textile dyes and their biotransformed products form the DNA and protein adducts at sub-cellular moiety. Moreover, these compounds catalyze the production of free radicals and oxidative stress, and trigger the apoptotic cascades to produce lesions in multiple organs. In addition, textile dyes modulate epigenetic factors like DNA methyltransferase and histone deacetylase to promote carcinogenesis. Several bioremediation approaches involving algae, fungi, bacteria, biomembrane filtration techniques, etc., have been tested and some other hybrid systems are currently under investigation to treat textile dye effluents. However, many such approaches are at the trial stage and require further research to develop more efficient, cost-effective, and easy-to-handle techniques.

We reinvestigate the question of whether a light Higgsino-like neutralino is a viable dark matter candidate. To this end we compute the dominant one-loop corrections to the masses of the Higgsino-like states in the minimal supersymmetric standard model (MSSM), due to loops involving heavy quarks and their superpartners. We also calculate analogous corrections to the couplings of Higgsino-like neutralinos to $Z$ and Higgs bosons. In the region of parameter space leading to high Higgsino purity of the lightest neutralino, these corrections can change the expected relic density by up to a factor of 5 in either direction. We conclude that for favorable choices of soft supersymmetry-breaking parameters, a state with more than 99% Higgsino purity could indeed form all cold dark matter in the Universe. In some cases these corrections can also increase the expected cross section for LSP scattering off spinless nuclei by up to two orders of magnitude, or reduce it to zero.

We discuss the viability of gb → tH → ttb charged-Higgs signals at the proposed LHC pp supercollider, in the decay channel tt → (bqq′)(bℓν). Here one top quark decays hadronically and one semileptonically, with all three b-quarks giving flavor-tagged jets. The principal backgrounds come from ttg, ttq, ttc and ttb continuum production, with possible mis-tagging of g, q and c. We conclude that significant signals can be separated from these backgrounds, for limited but interesting ranges of the parameters mH± and tan β, with the LHC energy and luminosity.

We investigate the impact of the 766.3 Ty KamLAND spectrum data on the determination of the solar neutrino oscillation parameters. We show that the observed spectrum distortion in the KamLAND experiment firmly establishes Δm212 to lie in the low-LMA solution region. The high-LMA solution is excluded at more than 4σ by the global solar neutrino and KamLAND spectrum data. The maximal solar neutrino mixing is ruled out at 6σ level. The 3σ allowed region in the Δm212–sin2θ12 plane is found to be remarkably stable with respect to leaving out the data from one of the solar neutrino experiments from the global analysis. We perform a three flavor neutrino oscillation analysis of the global solar neutrino and KamLAND spectrum data as well. The 3σ upper limit on sin2θ13 is found to be sin2θ13<0.055. We derive predictions for the CC to NC event rate ratio and day–night (D–N) asymmetry in the CC event rate, measured in the SNO experiment, and for the suppression of the event rate in the BOREXINO and LowNu experiments. Prospective high precision measurements of the solar neutrino oscillation parameters are also discussed.

Air pollution is a major risk factor for neurological disorders. Both indoor and outdoor dusts comprise different kinds of iron oxides in the nano-scale range. Due to their small size...

Out of the 15 3 × 3 neutrino mass matrices with two texture zeros, seven are compatible with the neutrino oscillation data. While two of them correspond to hierarchical neutrino masses and 1 to an inverted hierarchy, the remaining four correspond to degenerate masses. Moreover only the first three of the seven mass matrices are compatible with the maximal mixing angle of atmospheric neutrino and hence favored by data. We give compact expressions for mass matrices in terms of mass eigenvalues and study phenomenological implications for the seven cases. Similarity of the textures of the neutrino, charged-lepton mass matrices with those of quark mass matrices is also discussed.

We perform model independent and model dependent analyses of solar neutrino data including the neutral current event rate from SNO. The inclusion of the first SNO NC data in the model independent analysis determines the allowed ranges of $^{8}{B}$ flux normalisation and the $\nu_e$ survival probability more precisely than what was possible from the SK and SNO CC combination. We perform global $\nu_e-\nu_{active}$ oscillation analyses of solar neutrino data using the NC rate instead of the SSM prediction for the $^{8}{B}$ flux, in view of the large uncertainty in the latter. The LMA gives the best solution, while the LOW solution is allowed only at the $3\sigma$ level.

Relatively light electroweak superparticle masses are required to satisfy the bulk annihilation region of dark matter relic density and account for the observed excess of muon g − 2, while TeV scale squark and gluino masses are required to account for the 125 GeV Higgs boson mass and the negative SUSY search results from 7 TeV LHC in most SUSY models. These two sets of requirements can be reconciled in a simple nonuniversal gaugino mass model, which assumes SUSY breaking via a combination of two superfields belonging to the singlet and the 200-plet representations of the GUT group SU(5). The model can be probed via squark/gluon search with the present and future LHC data. In a more general nonuniversal gaugino mass model the squark and gluino masses can be raised to the edge of the discovery limit of 14 TeV LHC or beyond. This model can be probed, however, through the search for electroweak pair production of the relatively light sleptons and winos with the 14 TeV LHC data in future.

A heavy triplet of leptons (Σ+,Σ0,Σ−)R per family is proposed as the possible anchor of a small seesaw neutrino mass. A new U(1) gauge symmetry is then also possible, and the associated gauge boson X may be discovered at or below the TeV scale. We discuss the phenomenology of this proposal, with and without possible constraints from the NuTeV and atomic parity violation experiments, which appear to show small discrepancies from the predictions of the standard model.

We study a specific SUGRA model with nonuniversal gaugino masses as an alternative to the minimal SUGRA model in the context of supersymmetric dark matter. The lightest supersymmetric particle in this model comes out to be a Higgsino dominated instead of a bino dominated lightest neutralino. The thermal relic density of this Higgsino dark matter is somewhat lower than the cosmologically favoured range, which means it may be only a subdominant component of the cold dark matter. Nonetheless, it predicts favourable rates of indirect detection, which can be seen in square-km size neutrino telescopes.

The physics implications of the just published salt phase data from the SNO experiment are examined. The effect of these data on the allowed ranges of the solar neutrino oscillation parameters, Δm212 and sin2θ12, are studied in the cases of two- and three-neutrino mixing. In the latter case we derive an upper limit on the angle θ13. Constraints on the solar νe transitions into a mixture of active and sterile neutrinos are also presented. Finally, we give predictions for the day–night asymmetry in the SNO experiment, for the event rate in the BOREXINO and LowNu experiments, and discuss briefly the constraints on the solar neutrino oscillation parameters which can be obtained with prospective KamLAND data.

The recently observed five single-jet events with missing ${p}_{T}&gt;~35$ GeV can be consistently explained by gluinos ($\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}$), i.e., the supersymmetric partners of the gluons ($g$), produced via $q\stackrel{-}{q}\ensuremath{\rightarrow}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}$ and $\mathrm{gg}\ensuremath{\rightarrow}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}$, with a mass in the range $15\ensuremath{\lesssim}{m}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{q}}\ensuremath{\lesssim}45$ GeV. Reducing the ${p}_{T}^{\mathrm{miss}}$ cut to the $4\ensuremath{\sigma}$ level further constrains this range to $25\ensuremath{\lesssim}{m}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}}\ensuremath{\lesssim}45$ GeV.

A large and azimuthally isolated missing pT track is shown to be an effective signature for gluino production at the p̄p collider. Using this signature, gluino masses up to 40–50 GeV can be probed with the existing collider data; the absence of the predicted effects puts lower limits on gluino masses which are rather insensitive to the masses of other supersymmetric particles.

Pair production of a very heavy flavor like top leads to large-${p}_{T}$ isolated electrons back to back with jets as observed by Arnison et al. With a top-quark mass \ensuremath{\sim} 35 GeV, one can account for all the experimental features of these single-jet events available so far. Further tests for this interpretation are suggested.

The hadronic tau decay channel offers by far the best signature for heavy charged Higgs boson search at the LHC in the large $\tan\beta$ region. By exploiting the distinct polarization of the tau and its large transverse mass, along with the accompanying missing--$p_T$, one can probe for a charged Higgs boson up to a mass of about 600 GeV in an essentially background-free environment. The transverse mass distribution of the tau jet also provides a fairly unambiguous estimate of the charged Higgs boson mass.

We investigate the signature of a heavy charged Higgs boson of the minimal super-symmetric standard model in the lepton plus multijet channel at the CERN Large Hadron Collider with four b tags. The signal is the gluon-gluon fusion process $g\stackrel{\ensuremath{\rightarrow}}{g}t\overline{b}{H}^{\ensuremath{-}},$ followed by the ${H}^{\ensuremath{-}}\ensuremath{\rightarrow}\overline{t}b$ decay, while the main background is from $g\stackrel{\ensuremath{\rightarrow}}{g}t\overline{t}b\overline{b}.$ We find that the two can be separated effectively by kinematic cuts and mass reconstruction, but the signal size is not very large in the end. Nonetheless, with a good b-tagging efficiency ${\ensuremath{\epsilon}}_{b}\ensuremath{\sim}50%,$ this channel can provide a viable signature over a limited but interesting range of the parameter space.

We have constructed an explicit see-saw model containing two singlet neutrinos, one carrying a (B−3Le) gauge charge with an intermediate mass scale of ∼O(1010) GeV along with a sterile one near the GUT (grand unification theory) scale of ∼O(1016) GeV. With these mass scales and a reasonable range of Yukawa couplings, the model can naturally account for the near-maximal mixing of atmospheric neutrino oscillations and the small mixing matter-enhanced oscillation solution to the solar neutrino deficit.

We consider a R-parity-violating SUSY model, containing lepton-number-violating Yukawa couplings. Analysing the Tevatron dilepton data in terms of this model we get a lower mass limit of 100 GeV for squark and gluino. This is comparable to the corresponding limit obtained from the Tevatron missing-pT data in the R-conserving SUSY model. Taken together, they imply a lower squark/gluino mass limit of 100 GeV for any value of the relevant lepton-number-violating Yukawa couplings.

We re-investigate the question whether a light higgsino-like neutralino is a viable Dark Matter candidate. To this end we compute the dominant one-loop corrections to the masses of the higgsino-like states in the minimal Supersymmetric Standard Model (MSSM), due to loops involving heavy quarks and their superpartners. We also calculate analogous corrections to the couplings of higgsino-like neutralinos to Z and Higgs bosons. In the region of parameter space leading to high higgsino purity of the lightest neutralino, these corrections can change the expected relic density by up to a factor of five in either direction. We conclude that for favorable choices of soft supersymmetry breaking parameters, a state with more than 99% higgsino purity could indeed form all cold Dark Matter in the Universe. In some cases these corrections can also increase the expected cross section for LSP scattering off spinless nuclei by up to two orders of magnitude, or reduce it to zero.

We have considered nonuniversal gaugino mass models of supergravity, arising from a mixture of two superfield contributions to the gauge kinetic term, belonging to a singlet and a nonsinglet representation of the grand unified theory group. In particular we analyze two models, where the contributing superfields belong to the singlet and the 75-dimensional, and the singlet and the 200-dimensional representations of $SU(5)$. The resulting lightest superparticle is a mixed bino-Higgsino state in the first case and a mixed bino-wino-Higgsino state in the second. In both cases one obtains cosmologically compatible dark matter relic density over broad regions of the parameter space. We predict promising signals in direct dark matter detection experiments as well as in indirect detection experiments via high energy neutrinos coming from their pair annihilation in the Sun. Besides, we find interesting $\ensuremath{\gamma}$-ray signal rates that will be probed in the Fermi gamma-ray space telescope. We also expect promising collider signals at LHC in both cases.

We estimate the electron and neutron electric dipole moments in the focus point scenario of the minimal SUGRA model corresponding to large sfermion masses and moderate to large $\tan\beta$. There is a viable region of moderate fine-tuning in the parameter space, around $\tan\beta \simeq 5$, where the experimental limits on these electric dipole moments can be satisfied without assuming unnaturally small phase angles. But the fine-tuning constraints become more severe for $\tan\beta > 10$.

The first results from the KamLAND experiment have provided confirmational evidence for the Large Mixing Angle (LMA) MSW solution to the solar neutrino problem. We do a global analysis of solar and the recently announced KamLAND data (both rate and spectrum) and investigate its effect on the allowed region in the $\Delta m^2-\tan^2\theta$ plane. The best-fit from a combined analysis which uses the KamLAND rate plus global solar data comes at $\Delta m^2 = 6.06 \times 10^{-5}$ eV $^2$ and $\tan^2\theta=0.42$, very close to the global solar best-fit, leaving a large allowed region within the global solar LMA contour. The inclusion of the KamLAND spectral data in the global fit gives a best-fit $\Delta m^2 = 7.15 \times 10^{-5}$ eV $^2$ and $\tan^2\theta=0.42$ and constrains the allowed areas within LMA, leaving essentially two allowed zones. Maximal mixing though allowed by the KamLAND data alone is disfavored by the global solar data and remains disallowed at about $3\sigma$. The LOW solution is now ruled out at about 5$\sigma$ w.r.t. the LMA solution.

Right-handed neutrinos with a large Majorana mass occur naturally in the left-right-symmetric model. We explore the prospect of such a heavy right-handed neutrino search via ${\mathit{W}}_{\mathit{R}}$ decay in the like-sign dilepton channel at the Superconducting Super Collider (SSC) and CERN Large Hadron Collider (LHC). The standard model background can be effectively eliminated by suitable lepton ${\mathit{p}}_{\mathit{T}}$ and isolation cuts without affecting the signal cross section seriously. In this way it seems possible to explore the bulk of the parameter space 0${\mathit{M}}_{\mathit{N}\mathit{R}}$${\mathit{M}}_{\mathit{W}\mathit{R}}$, with ${\mathit{M}}_{\mathit{W}\mathit{R}}$ going up to 3000 (2000) GeV at energies reached at the SSC (LHC).

We incorporate QCD corrections into the calculation of signals for charged Higgs bosons produced in t-quark decays at the tevatron energy, in the leading-log approximation. We find that the signal in the 2τ channel is enhanced by up to a factor of three in the region tan β≲1, essentially closing this window where a light charged Higgs might escape discovery. The signal is reduced somewhat for large tan β, but remains viable there.

The recently observed hadronic single- and multijet events accompanied by large missing ${p}_{T}$ can be consistently explained by gluinos (g\ifmmode \tilde{}\else \~{}\fi{}), produced via qq\ifmmode\bar\else\textasciimacron\fi{},gg\ensuremath{\rightarrow}g\ifmmode \tilde{}\else \~{}\fi{} g\ifmmode \tilde{}\else \~{}\fi{} with an optimal mass of ${m}_{g\ifmmode \tilde{}\else \~{}\fi{}}$=35 to 45 GeV. This result agrees surprisingly well with theoretical predictions of the minimal N=1 supergravity model. Adopting the theoretically somewhat less appealing alternative where scalar quarks (q\ifmmode \tilde{}\else \~{}\fi{}) are lighter than gluinos such that they are dominantly produced via qq\ifmmode\bar\else\textasciimacron\fi{},gg\ensuremath{\rightarrow}q\ifmmode \tilde{}\else \~{}\fi{} q\ifmmode \tilde{}\else \~{}\fi{}, the events can also be explained by scalar quarks in a similar mass range. Currently available data, including the observed jet properties, cannot meaningfully distinguish between these two mechanisms. In addition we present detailed predictions for cross sections and distributions in 〈${E}_{T}$〉, ${p}_{T}^{\mathrm{miss}}$, ${p}_{T}^{\mathrm{jet}}$, and invariant observed jet masses for gluino as well as scalar-quark production at present and forthcoming CERN pp\ifmmode\bar\else\textasciimacron\fi{} collider energies (\ensuremath{\surd}s =540 and 620 GeV). Realistic tests are suggested which would allow discrimination between gluinos and scalar quarks in the near future.

The opposite states of the \ensuremath{\tau} polarization resulting from the charged Higgs boson and the W boson decays can be exploited to enhance the ${\mathit{H}}^{\ifmmode\pm\else\textpm\fi{}}$ signal in the inclusive one-prong hadronic decay channel of \ensuremath{\tau}. We suggest practical methods of sharpening up the ${\mathit{H}}^{\ifmmode\pm\else\textpm\fi{}}$ signature in the top quark decay at the CERN LHC using this idea. As a result one can carry on the charged Higgs boson search to within \ensuremath{\sim}20 GeV of the parent top quark mass over the full parameter space of the MSSM. \textcopyright{} 1996 The American Physical Society.

The τ polarization has a fairly significant effect on the charged Higgs signature at the hadron colliders. It is best seen in the τμ channel followed by the pionic decay of τ. The average pT of the pion originating from the W boson is only about half of that originating from a charged Higgs of comparable mass. This can be used to improve the signal/background ratio by a factor of ∼ 3. It can also serve as an independent signature for the charged Higgs boson.

Assuming the existence of a gauge boson $X$ which couples to ${B\ensuremath{-}3L}_{\ensuremath{\tau}},$ we discuss the present experimental constraints on ${g}_{X}$ and ${m}_{X}$ from $\stackrel{\ensuremath{\rightarrow}}{Z}{l}^{+}{l}^{\ensuremath{-}}$ and $\stackrel{\ensuremath{\rightarrow}}{Z}\overline{f}fX(f=q,{\ensuremath{\nu}}_{\ensuremath{\tau}},\ensuremath{\tau}).$ We also discuss the discovery potential of $X$ at hadron colliders through its decay into ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ pairs. In the scenario where all three charged leptons (and their neutrinos) mix, lepton flavor nonconservation through $X$ becomes possible and provides another experimental probe into this hypothesis.

We explore the prospect of a charged Higgs boson search in top quark decay at the Fermilab Tevatron collider upgrade, taking advantage of the opposite states of \ensuremath{\tau} polarization resulting from the ${\mathit{H}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${\mathit{W}}^{\ifmmode\pm\else\textpm\fi{}}$ decays. Methods of distinguishing the two contributions in the inclusive one-prong hadronic decay channel of \ensuremath{\tau} are suggested. The resulting signature and discovery limit of ${\mathit{H}}^{\ifmmode\pm\else\textpm\fi{}}$ are presented for the Tevatron upgrade as well as the ${\mathrm{Tevatron}}^{\mathrm{*}}$ and the DiTevatron options.

The CP-violating MSSM allows existence of a light neutral Higgs boson (MH1≲50GeV) in the CPX scenario in the low tanβ(≲5) region, which could have escaped the LEP searches due to a strongly suppressed H1ZZ coupling. This parameter space corresponds to a relatively light H+ (MH+<Mt), which is predicted to decay dominantly into the WH1 channel. Thus one expects to see a striking tt¯ signal at the LHC, where one of the top quarks decays into the bbb¯W channel, via t→bH±, H±→WH1 and H1→bb¯. The characteristic correlation between the bb¯, bb¯W and bbb¯W invariant mass peaks is expected to make this signal practically free of the SM background. Our parton level Monte Carlo simulation yields upto 5000 events, for L=30fb−1, over the parameter space of interest, after taking into account the b-tagging efficiency for three or more b-tagged jets.

We investigate the phenomenology of a wino lightest superparticle as obtained in anomaly mediated supersymmetry breaking and some string models. The Wilkinson Microwave Anisotropy Probe constraint on the dark matter relic density implies a wino lightest superparticle mass of 2.0--2.3 TeV. We find a viable signature for such a heavy wino at CLIC, operating at its highest center of mass energy of 5 TeV. One also expects a viable monochromatic $\ensuremath{\gamma}$-ray signal from its pair-annihilation at the galactic center at least for cuspy dark matter halo profiles.

We study the signature of $H^\pm$ decay into $h^0W$ at the LHC in SUSY models. It has only marginal viability in the MSSM. But in the singlet extensions like the NMSSM one can have a spectacular signature for $H^\pm$ decay into $(h^0,A^0)W$ over a significant domain of parameter space.

The isolated like sign dilepton signature for gluino production is investigated at the CERN LHC energy for the R-conserving as well as the L- and B-violating SUSY models over a wide range of the parameter space. One gets viable signals for gluino masses of 300 and 600 GeV for both R-conserving and L-violating models, while it is less promising for the B-violating case. For a 1000 GeV gluino, the L-violating signal should still be viable; but the R-conserving signal becomes too small at least for the low luminosity option of the LHC.

A systematic analysis of the like-sign dipleton signature for gluino production at LHC is performed in the $R$-conserving minimal supersymmetric standard model, taking into account the top quark and Higgs boson effects in the cascade decay. We consider two representative values of the gluino mass, 300 and 800 GeV, along with those of the other SUSY parameters. While the top quark contribution is kinematically suppressed for the former case it is very import for the latter. Ways of separating the signal from the background are discussed. One expects a viable LSD signals upto a gluino mass of $\sim 800$ (1200) GeV at the low (high) luminosity option of LHC over practically the full parameter space of MSSM.

Assuming a top-quark mass of about 150 GeV we analyze the prospects for a charged-Higgs-boson search in top-quark decay at the Fermilab Tevatron upgrade. Universality predicts the relative size of the top decay signal via $W$ boson in different decay channels, and an observable excess over this prediction can be used as a signature for charged-Higgs-boson production. In the charged-Higgs-boson-fermion coupling scheme suggested by minimal supersymmetry and ${\mathrm{E}}_{6}$ string-inspired models one expects to see an observable signal up to a charged-Higgs-boson mass of 100 GeV throughout the allowed range of the coupling parameter $tan\ensuremath{\beta}$. The absence of such a signal would give an unambiguous charged-Higgs-boson mass limit of 100 GeV. This is not possible however in the alternative coupling schemes of two-Higgs-doublet models.

This review starts with a brief introduction to the charged Higgs boson (H ± ) in the Minimal Supersymmetric Standard Model (MSSM). It then discusses the prospects of a relatively light H ± boson search via top quark decay at Tevatron/LHC, and finally a heavy H ± boson search at LHC. The viable channels for H ± search are identified in both the cases, with particular emphasis on the H ± →τν decay channel. The effects of NLO QCD correction in the SM as well as the MSSM are discussed briefly.

On the basis of previous analyses of the jet plus missing-pT events at the pp collider energy √s = 540 GeV, we give parameter-free predictions for event rates at √s = 630 GeV expected by supersymmetric scenarios. In particular a comparable or even larger two-jet event rate, relative to one-jet events, has to be observed if the supersymmetric interpretation of “anomalous” missing-pT events should continue to hold. Otherwise the new data for √s = 630 GeV place stringent lower bounds on gluino and squark masses.

The most natural region of cosmologically compatible dark matter relic density in terms of low fine-tuning in a minimal supersymmetric standard model with nonuniversal gaugino masses is the so called bulk annihilation region. We study this region in a simple and predictive SUSY-GUT model of nonuniversal gaugino masses, where the latter transform as a combination of singlet plus a nonsinglet representation of the GUT group SU(5). The model prediction for the direct dark matter detection rates is well below the present CDMS and XENON100 limits, but within the reach of a future 1Ton XENON experiment. The most interesting and robust model prediction is an indirect detection signal of hard positron events, which resembles closely the shape of the observed positron spectrum from the PAMELA experiment.

If the charged Higgs boson ${H}^{+}$ exists with ${m}_{{H}^{+}}&lt;{m}_{t}{+m}_{b}$, the conventional expectation is that it will decay dominantly into $c\overline{s}$ and ${\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}}$. However, the three-body decay mode ${H}^{+}\ensuremath{\rightarrow}{W}^{+}b\overline{b}$ is also present and we show that it becomes very important in the low $\mathrm{tan}\ensuremath{\beta}$ region for ${m}_{{H}^{+}}\ensuremath{\gtrsim}140\mathrm{GeV}$. We then explore its phenomenological implications for the charged-Higgs-boson search in top-quark decay.

The minimal supergravity model predicts the polarization of the tau coming from the stau to bino decay in the co-annihilation region to be $+1$. This can be exploited to extract this soft tau signal at LHC and also to measure the tiny mass differences between the stau and the bino lightest superparticle. Moreover, this strategy will be applicable for a wider class of bino lightest superparticle models, where the lighter stau has a right component at least of similar size as the left.

We study two simple and well-motivated nonuniversal gaugino mass models, which predict Higgsino dark matter. One can account for the observed dark matter relic density along with the observed Higgs boson mass of $\ensuremath{\simeq}125\text{ }\text{ }\mathrm{GeV}$ over a large region of the parameter space of each model, corresponding to a Higgsino mass of $\ensuremath{\simeq}1\text{ }\text{ }\mathrm{TeV}$. In each case this parameter region covers the gluino mass range of 2--3 TeV, parts of which can be probed by the 14 TeV LHC experiments. We study these model predictions for the LHC in brief and for dark matter detection experiments in greater detail.

We propose a simple unified description of two recent precision measurements which suggests new physics beyond the standard model of particle interactions, i.e., the deviation of ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{W}$ in deep inelastic neutrino-nucleon scattering and that of the anomalous magnetic moment of the muon. Our proposal is also consistent with a third precision measurement, i.e., that of parity nonconservation in atomic cesium, which agrees with the standard model.

In many SUSY models the first SUSY signal in the proposed International Linear Collider is expected to come from the pair production of $\tilde\tau_1$, followed by its decay into $\tau$+LSP. We study a simple and robust method of measuring the polarization of this $\tau$ in its 1-prong hadronic decay channel,and show how it can be used to discriminate between SUSY models and to determine SUSY parameters.

A hard intrinsic charm component of the nucleon, as recently deduced from the charm hadroproduction data, is shown to account for the anomalously small scale breaking ($\ensuremath{\Lambda}\ensuremath{\simeq}0.1$ GeV) observed in the $\ensuremath{\mu}N$ data of Norton et al. (European Muon Collaboration), without affecting the results ($\ensuremath{\Lambda}=0.3\ensuremath{-}0.4$ GeV) of the SLAC-MIT (Stanford Linear Accelerator Center-Massachusetts Institute of Technology) or CDHS (CERN-Universit\"at Dortmund-Universit\"at Heidelberg-Centre d'Etudes Nucl\'eaires de Saclay) Collaborations.

Abstract Developing methods that activate C−H bonds directly with high selectivity for C−C bond formation in complex organic synthesis has been a major chemistry challenge. Recently it has been shown that photoactivation of weakly polarized C−H bonds can be carried out inside a cationic water‐soluble nanocage with visible light‐mediated host‐guest charge transfer (CT) chemistry. Using this novel photoredox activation paradigm, here we demonstrate C−C bond formation to photo‐generate 1,3‐diynes at room temperature in water from terminal aromatic alkynes for the first time. The formation of cavity‐confined alkyne radical cation and the proton‐removed neutral radical species highlight the unique C−C coupling step driven by supramolecular preorganization.

We present a minimal seesaw model based on an extension of the standard model (SM) which includes an additional U(1), with gauge charge $B\ensuremath{-}\frac{3}{2}{(L}_{\ensuremath{\mu}}{+L}_{\ensuremath{\tau}})$. The requirement of anomaly cancellation implies the existence of two right-handed singlet neutrinos, carrying this gauge charge, which have normal Dirac couplings to ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ but suppressed ones to ${\ensuremath{\nu}}_{e}.$ Assuming the U(1) symmetry breaking scale to be ${10}^{12}\ensuremath{-}{10}^{16}$ GeV, this model can naturally account for the large (small) mixing solutions to the atmospheric (solar) neutrino oscillations.

We study the kinematic cuts which can be used to enhance the charged Higgs signal over the W boson background, for mH±>mw, in the decay of a heavy top quark at LHC energy. With suitable cuts it is possible to ensure a sizeable signal and a signal-to-background ratio ≳ 1 up to mH±⋍mt−20 GeV, which hold throughout the allowed coupling parameter (tan β) space in the minimal SUSY model. Thus one should be able to search for the charged Higgs boson to within 20 GeV of the parent top quark mass at the LHC/SSC colliders, i.e., up to 130 GeV for mt⋍150 GeV, going up to 180 GeV for mt⋍200 GeV.

In the Majoron models the SU(2) Higgs doublet can decay invisibly into a Majoron pair via its mixing with a singlet. An analysis of the CERN LEP data shows the invisible decay mode to be more visible than the SM decay. For these models, the dominantly doublet Higgs field $H$ is shown to have a mass limit within \ifmmode\pm\else\textpm\fi{}6 GeV of the SM limit irrespective of the model parameters. But the dominantly singlet one $S$ can be arbitrarily light for a sufficiently small mixing angle.

The like sign dileptons provide the most promising signature for superparticle search in a large category of $R$-parity violating SUSY models. We estimate the like sign dilepton signals at the Tevatron collider, predicted by these models, over a wide region of the MSSM parameter space. One expects an unambiguous signal upto a gluino mass of $200 - 300$ GeV ($\geq 500$ GeV) with the present (proposed) accumulated luminosity of $\sim 0.1~(1)~{\rm fb}^{-1}$.

We propose a simple texture of the neutrino mass matrix with one sterile neutrino along with the three standard ones. It gives maximal mixing angles for νe→νS and νμ→ντ oscillations or vice versa. Thus with only four parameters, this mass matrix can explain the solar neutrino anomaly, atmospheric neutrino anomaly, LSND result and the hot dark matter of the universe, while satisfying all other Laboratory constraints. Depending on the choice of parameters, one can get the vacuum oscillation or the large angle MSW solution of the solar neutrino anomaly.

We study signals for the production of superparticles at the Tevatron in supergravity scenarios based on the Grand Unified group SO(10). The breaking of this group introduces extra contributions to the masses of all scalars, described by a single new parameter. We find that varying this parameter can considerably change the size of various expected signals studied in the literature, with different numbers of jets and/or charged leptons in the final state. The ratios of these signal can thus serve as a diagnostic to detect or constrain deviations from the much--studied scenario where all scalar masses are universal at the GUT scale. Moreover, under favorable circumstances some of these signals, and/or new signals involving hard $b-$jets, should be observable at the next run of the Tevatron collider even if the average scalar mass lies well above the gluino mass.

On the basis of a detailed phenomenological analysis, combined with the minimal N = 1 supergravity model, it is shown that the jet plus missing-pT events at the pp collider can only be explained by relatively light gluinos (mg̃ < m q̃ with a mass of about 40 GeV. The resulting squark and slepton masses are then found to be q̃ > 50 GeV and mẽ > 35 GeV.

A model is presented for diffractive charm-anticharm production in neutrino reactions, which can account for all the essential features of the like-sign dimuon data.Received 1 March 1982DOI:https://doi.org/10.1103/PhysRevLett.48.1711©1982 American Physical Society

We have analyzed the prospect of probing a nonuniversal gaugino mass model of mixed bino-Higgsino dark matter at the current 7 TeV run of LHC. It provides cosmologically compatible dark matter relic density over two broad bands of parameters, corresponding to ${m}_{\stackrel{\texttildelow{}}{g}}&lt;{m}_{\stackrel{\texttildelow{}}{q}}$ and ${m}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\sim}{m}_{\stackrel{\texttildelow{}}{q}}$. The supersymmetry spectrum of this model has two distinctive features: (i) an approximate degeneracy among the lighter chargino and neutralino masses, and (ii) an inverted mass hierarchy of squark masses. We find that these features can be exploited to obtain a viable signal up to ${m}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\sim}800\text{ }\text{ }\mathrm{GeV}$ over both the parameter bands with an integrated luminosity $5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$.

In a wino LSP scenario the annihilation cross-section of winos gravitationally bound in galaxies can be boosted by a Sommerfeld enhancement factor which arises due to the ladder of exchanged W bosons between the initial states. The boost factor obtained can be in the range S ≃10 4 if the mass is close to the resonance value of M ≃4 TeV . In this paper we show that if one takes into account the Sommerfeld enhancement in the relic abundance calculation then the correct relic density is obtained for 4 TeV wino mass due to the enhanced annihilation after their kinetic decoupling. At the same time the Sommerfeld enhancement in the χχ→W + W - annihilation channel is sufficient to explain the positron flux seen in PAMELA data without significantly exceeding the observed antiproton signal. We also show that (e - +e + ) and γ-ray signals are broadly compatible with the Fermi-LAT observations. In conclusion we show that a 4 TeV wino DM can explain the positron and antiproton fluxes observed by PAMELA and at the same time give a thermal relic abundance of CDM consistent with WMAP observations.

We consider the contribution of radially excited 2^3P_{1,2} states to psi^prime production at the Tevatron energy. Production of these states via the conventional gluon fusion mechanism and via gluon and charm quark fragmentation processes is considered. We find that it is possible to account for the data on psi^prime production from the CDF experiment, by taking into account the decays of these 2^3P_{1,2} states into psi^prime.

The top quark data in the lepton plus $\ensuremath{\tau}$ channel offers a viable probe for the charged Higgs boson signal. We analyze the recent Collider Detector at Fermilab data in this channel to obtain a significant limit on the ${H}^{\ifmmode\pm\else\textpm\fi{}}$ mass in the large $\mathrm{tan}\ensuremath{\beta}$ region.

We point out that present experimental limits from searches for neutral Higgs bosons at LEP already imply stringent lower bounds on the mass of the charged Higgs boson in the Minimal Supersymmetric Standard Model (MSSM); these bounds are especially severe for low values of \tanb ($\tanb \leq 3$), where the $H^+ \bar{t} b$ coupling is large. However, these indirect constraints are much weaker in simple extensions of the MSSM Higgs sector involving the introduction of an extra U(1) gauge group or an extra $SU(2) \times U(1)_Y$ Higgs singlet field; in the latter case charged Higgs bosons can even be light enough to be pair produced at LEP.

We explore the possibility of an energy independent suppression of the solar neutrino flux in the context of the recent SuperKamiokande data. From a global analysis of the rate and spectrum data, this scenario is allowed at only 14% probability with the observed Cl rate. If we allow for a 20% upward renormalization of the Cl rate along with a downward renormalization of the B neutrino flux then the fit improves considerably to a probability of $\ensuremath{\sim}50%.$ We compare the quality of these fits with those of the MSW solutions. These renormalizations are also found to improve the quality of the fits with MSW solutions and enlarge the allowed region of their validity in the parameter space substantially. Over much of this enlarged region the matter effects on the suppression of the solar neutrino flux are found to be very weak, so that the solutions become practically energy independent.

The global data on solar neutrino rates and spectrum, including the SNO charged current rate, can be explained by LMA, LOW or the energy independent solution -- corresponding to near-maximal mixing. All the three favour a mild upward renormalisation of the Cl rate. A mild downward shift of the $B$ neutrino flux is favoured by the energy independent and to a lesser extent the LOW solution, but not by LMA. Comparison with the ratio of SK elastic and SNO charged current scattering rates favours the LMA over the other two solutions, but by no more than $1.5\sigma$.

In the minimal SUGRA model the lighter tau slepton is expected to be the second lightest superparticle over a large parameter range at large tanβ. Consequently one expects a viable SUGRA signal at LHC in the tau lepton channel coming from the decay of these tau sleptons. The model predicts the polarization of this tau lepton to be +1 to a very good accuracy. We show how this prediction can be tested by looking at the momentum fraction of the tau-jet, carried by the charged prong, in its 1-prong hadronic decay channel.

We do a re-analysis to asses the impact of the results of the Borexino experiment and the recent 2.8 KTy KamLAND data on the solar neutrino oscillation parameters. The current Borexino results are found to have no impact on the allowed solar neutrino parameter space. The new KamLAND data causes a significant reduction of the allowed range of $Δm^2_{21}$, determining it with an unprecedented precision of 8.3% at 3$σ$. The precision of $Δm^2_{21}$ is controlled practically by the KamLAND data alone. Inclusion of new KamLAND results also improves the upper bound on $\sin^2θ_{12}$, but the precision of this parameter continues to be controlled by the solar data. The third mixing angle is constrained to be $\sin^2θ_{13} &lt; 0.063$ at $3σ$ from a combined fit to the solar, KamLAND, atmospheric and CHOOZ results. We also address the issue of how much further reduction of allowed range of $Δm^2_{21}$ and $\sin^2θ_{12}$ is possible with increased statistics from KamLAND. We find that there is a sharp reduction of the $3σ$ ``spread'' with enhanced statistics till about 10 KTy after which the spread tends to flatten out reaching to less than 4% with 15 KTy data. For $\sin^2θ_{12}$ however, the spread is more than 25% even after 20 KTy exposure and assuming $θ_{12} &lt; π/4$, as dictated by the solar data. We show that with a KamLAND like reactor ``SPMIN'' experiment at a distance of $\sim$ 60 km, the spread of $\sin^2θ_{12}$ could be reduced to about 5% at $3σ$ level while $Δm_{21}^2$ could be determined to within 4%, with just 3 KTy exposure.

Top squark contributions to the radiative correction to ${R}_{b}$ and the top quark decay are analyzed over the relevant MSSM parameter space. One sees a 30% increase in the former along with a similar drop in the latter in going from the Higgsino-dominated to the mixed region. Consequently, one can get a viable SUSY contribution to ${R}_{b}$ within the constraint of the top quark data only in the mixed region, corresponding to a photino-dominated LSP. We discuss the phenomenological implications of this model for top quark decay and direct top squark production, which can be tested with the Fermilab Tevatron data.

Many extensions of the standard electroweak model Higgs sector suggest that the main Higgs decay channel is "invisible", for example, $h \to J J$ where $J$ denotes the majoron, a weakly interacting pseudoscalar Goldstone boson associated to the spontaneous violation of lepton number. In many of these models the Higgs boson may also be produced in association to a massive pseudoscalar boson (HA), in addition to the standard Bjorken mechanism (HZ). We describe a general strategy to determine limits from LEP data on the masses and couplings of such Higgs bosons, using the existing data on acoplanar dijet events as well as data on four and six $b$ jet event topologies. For the sake of illustration, we present constraints that can be obtained for the ALEPH data.

We report on a plan to establish a "Dictionary of LHC Signatures", an initiative that started at the WHEPPX workshop in January 2008. This study aims towards the strategy on distinguishing of 3 classes of dark matter motivated scenarios such as R-parity conserved supersymmetry, Little Higgs models with T-parity conservation and Universal Extra Dimensions with KK-parity for generic cases of their realization in wide range of the model space. Discriminating signatures are tabulated and will need a further detailed analysis.

We consider two optimally mixed neutralino dark matter models, based on nonuniversal gaugino masses, which were recently proposed by us to achieve WMAP compatible relic density over a large part of the minimal supersymmetric standard model parameter space. We compare the resulting predictions for the spin-independent dark matter scattering cross section with the recent CDMS II data, assuming the possibility of the two reported candidate events being signal events. For one model the predicted cross section agrees with the putative signal over a small part of the parameter space, while for the other the agreement holds over the entire WMAP compatible parameter space of the model.

In going from SPPS to Tevatron collider energy, one expects over an order of magnitude rise in the top quark production cross section as well as the relative size of the QCD (tt) to the W decay (tb) contribution. Consequently one should be able to probe the top quark mass up to 80 GeV at the Tevatron collider, the predominant contribution coming from the QCD process. A clean signature for the top quark is suggested.

This review starts with a brief introduction to the charged Higgs boson $(H^\pm)$ in the Minimal Supersymmetric Standard Model (MSSM). It then discusses the prospects of a relatively light $H^\pm$ boson search via top quark decay and finally a heavy $H^\pm$ boson search at LHC. The viable channels for $H^\pm$ search are discussed, with particular emphasis on the $H^\pm -> tau+nu$ decay channel.

Report of the Higgs working group for the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001. It contains 7 separate sections: A. Theoretical Developments B. Higgs Searches at the Tevatron C. Experimental Observation of an invisible Higgs Boson at LHC D. Search for the Standard Model Higgs Boson using Vector Boson Fusion at the LHC E. Study of the MSSM channel $A/H \to ττ$ at the LHC F. Searching for Higgs Bosons in $t\bar t H$ Production G. Studies of Charged Higgs Boson Signals for the Tevatron and the LHC

Using a Schwarz inequality, derived recently from unitary and Zweig suppression, we estimate a lower bound on the muoproduction of charm, in terms of forward ψ-electro (muo)production, which in turn is extrapolated from ψ-photoproduction. The resulting bound on the σ(μN→μμX)σ(μN→μX) ratio (≳1500) is already comparable to the experimental rate, which strongly suggests charm as the dominant mechanism for muon induced dimuons.

The weak charge ${Q}_{W}$ measured in atomic parity violation experiments can receive compensating contributions from more than one new physics source. We show explicitly that the $\ensuremath{\Delta}{Q}_{W}$ contribution from the exchange of an extra $Z$-boson can cancel that from the $s$-channel scalar top or scalar charm exchange in $R$-parity violating SUSY models proposed to explain the DESY HERA high-${Q}^{2}$ anomaly.

This is a phenomenological review of $R$ parity violating SUSY models, with particular emphasis on explicit $R$ parity violation.

We investigate the potential of 3 kiloTon-years(kTy) of KamLAND data to further constrain the $Δm^2$ and $\tan^2θ$ values compared to those presently allowed by existing KamLAND and global solar data. We study the extent, dependence and characteristics of this sensitivity in and around the two parts of the LMA region that are currently allowed. Our analysis with 3 kTy simulated spectra shows that KamLAND spectrum data by itself can constrain $Δm^2$ with high precision. Combining the spectrum with global solar data further tightens the constraints on allowed values of $\tan^2θ$ and $Δm^2$. We also study the effects of future neutral current data with a total error of 7% from the Sudbury Neutrino Observatory. We find that these future measurements offer the potential of considerable precision in determining the oscillation parameters (specially the mass parameter).

We calculate the higher-order Higgs particle production process gg→gH for a large top-quark mass (2mt > mH). We compute the resulting associated cross section for intermediate-mass Higgs particle (mW<mH<2mW) at SSC, followed by its dominant decay mode into a bottom-quark pair. At large pT the cross section becomes comparable to that of the QCD background while remaining sufficiently large for detection at SSC.

After a brief introduction to neutrino mass via the see-saw model I discuss neutrino mixing and oscillation, first in vacuum and then its matter enhancement. Then the solar and atmospheric neutrino oscillation data are briefly reviewed. Finally I discuss the problem of reconciling hierarchical neutrino masses with at least one large mixing, as implied by these data. A minimal see-saw model for reconciling the two is discussed.

The most promising source of SUGRA signal at the Tevatron collider is the pair-production of electroweak gauginos, followed by their leptonic decay. In the parameter range corresponding to dominant leptonic decay of these gauginos one or more of the leptons are expected to be $\tau$ with $P_\tau \simeq +1$. This polarization can be effectively used to distinguish the signal from the background in the 1-prong hadronic decay channel of $\tau$ by looking at the fractional $\tau$-jet momentum carried by the charged prong.

We discuss the SUSY dark matter phenomenology in some simple and predictive models of nonuniversal gaugino masses at the GUT scale. Assuming the gaugino masses to transform as a sum of singlet and a nonsinglet representation of the GUT group SU(5), one can evade the LEP constraints to access the bulk annihilation region of the bino dark matter relic density. Besides, with this assumption one can also have a mixed gaugino-higgsino dark matter, giving the right relic density over large parts of the parameter space. We consider the model predictions for LHC and dark matter experiments in both the cases. Finally we consider the AMSB model prediction of wino dark matter giving the right relic density for TeV scale wino mass. Assuming this wino dark matter mass to be at the first Sommerfeld resonance of about 4 TeV one can simultaneously reproduce the right relic density as well as the hard positron spectrum observed by the PAMELA experiment.

Till 2010 we had three unknown parameters of neutrino oscillation: the third mixing angle {\theta}_(13), the sign of the larger mass difference {\Delta}m^(2)_(31) and the CP violating phase {\delta}. Thanks to a number of consistent experimental results since then, culminating in the recent Daya Bay reactor neutrino data, we have a definitive determination of {\theta}_(13) now. Moreover its measured value, sin^(2)_(2 {\theta}_(13)) = 0.1, is close to its earlier upper limit. This has promising implications for the determination of the two remaining unknown parameters from the present and proposed accelerator neutrino experiments in the foreseeable future. This article presents a pedagogical review of these profound developments for the wider community of young physicists including university students.

The dimuon and dielectron data from the Fermilab Tevatron $\overline{p}p$ collider are used to probe for heavy quarks, which decay dominantly via flavor-changing neutral currents (FCNC's). Depending on whether the FCNC decay occurs at the tree or loop level, one gets a lower mass limit of 85 or 75 GeV. The former applies to singlet, vector doublet, and mirror-type quarks while the latter applies to a left-handed quark doublet of the fourth generation.

The muon energy spectra of the quasi-elastic and 1-pion production events in a LBL experiment, like K2K, are predicted to follow closely the neutrino energy spectrum, with downward shifts of the energy scale by $<Q^2>/2 M$ and $(<Q^2> + M_\Delta^2 - M^2)/2 M$ respectively. These predictions seem to agree with the observed muon spectra in the K2K nearby detector. The corresponding muon spectra in the far-away (SK) detector are predicted to show characteristic spectral distortions induced by $\nu_\mu$ oscillation. Comparison of the predicted spectral distortions with the observed muon spectra of the 1-Ring and 2-Ring muon events in the SK detector will help to determine the oscillation parameters. The results will be applicable to other LBL experiments as well.

This is a summary of the projects undertaken by the working group I on high energy and collider physics.

Our concept of the basic constituents of matter has undergone two revolutionary changes -- from atoms to proton &amp; neutron and then onto quarks &amp; leptons. Indeed all these quarks and leptons have been seen by now along with the carriers of their interactions, the gauge bosons. But the story is not complete yet. A consistent theory of mass requires the presence of Higgs bosons along with SUSY particles, which are yet to be seen. This is a turn of the century account of what has been achieved so far and what lies ahead.

In the Higgs sector of the minimal supersymmetric standard model, the mass of the pseudoscalar $A$ is an independent parameter together with $\mathrm{tan}\ensuremath{\beta}\ensuremath{\equiv}{v}_{2}{/v}_{1}$. If ${m}_{A}$ is small, then the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}h+A$ is kinematically allowed and is suppressed only if $\mathrm{tan}\ensuremath{\beta}$ is small, i.e., less than one. On the other hand, the mass of the charged Higgs boson is now near ${M}_{W},$ and the decay $t\ensuremath{\rightarrow}{b+h}^{+}$ is enhanced if $\mathrm{tan}\ensuremath{\beta}&lt;1$. Since the former has not been observed, and the branching fraction of $t\ensuremath{\rightarrow}b+W$ cannot be too small (by comparing the experimentally derived $t\overline{t}$ cross section from the leptonic channels with the theoretical prediction), we can infer a phenomenological lower bound on ${m}_{A}$ of at least 60 GeV for all values of $\mathrm{tan}\ensuremath{\beta}$.

We discuss an optimal $R$-parity breaking SUSY solution to the $R_b$ excess as well as the ALEPH 4-jet anomaly. The latter arises from the pair production of stop via chargino decay at LEP1.5, followed by its $R$--violating decay into a light quark pair. The model satisfies top quark and $Z$--boson decay constraints along with gaugino mass unification.

The т polarisation can be easily measured at the LHC in the 1-prong hadronic т decay channel by measuring what fraction of the т-jet momentum is carried by the charged track. A simple cut requiring this fraction to be τ; 0.8 retains most of the P т=+1 т -jet signal while suppressing the P т=−1 т-jet background and practically eliminating the fake t background. This can be utilised to extract the charged Higgs signal. It can be also utilised to extract the SUSY signal in the stau NLSP region, and in particular the stau co-annihilaton region.

We report on a plan to establish a Dictionary of LHC Signatures, an initiative that started at the WHEPPX workshop in January 2008. This study aims towards the strategy on distinguishing of 3 classes of dark matter motivated scenarios such as R-parity conserved supersymmetry, Little Higgs models with T-parity conservation and Universal Extra Dimensions with KK-parity for generic cases of their realization in wide range of the model space. Discriminating signatures are tabulated and will need a further detailed analysis.

There is a strong correlation between the $p_T$ and isolation of the lepton coming from $B$ decay. Consequently the isolated lepton background from $B$ decay goes down rapidly with increasing lepton $p_T$; and there is a $p_T$ cutoff beyond which it effectively vanishes. For the isolation cut of $E^{AC}_T < 10$ GeV, appropriate for LHC, the lepton $p_T$ cutoff is 80 GeV. This can be exploited to effectively eliminate the $B$ background from the like sign dilepton channel apropriate for Majorana particle searches, as well as the unlike sign dilepton and the single lepton channels appropriate for the top quark search. We illustrate this with a detailed analysis of the $B$ background in these channels along with the signals at LHC energy using both parton level MC and ISAJET programs.

The favored $R$-parity-violating SUSY scenarios for the anomalous DESY HERA events correspond to top and charm squark production via the ${\ensuremath{\lambda}}_{131}^{\ensuremath{'}}$ and ${\ensuremath{\lambda}}_{121}^{\ensuremath{'}}$ couplings. In both cases the corresponding electronic branching fractions of the squarks are expected to be $\ensuremath{\ll}1$. Consequently the canonical leptoquark signature is incapable of probing these scenarios at the Fermilab Tevatron collider over most of the MSSM parameter space. We suggest alternative signatures for probing them at Tevatron, which seem to be viable over the entire range of MSSM parameters.

We reanalyze a topless left-right model due to Ma, after allowing flavor-changing neutral currents which are consistent with all the experimental limits coming from flavor-changing processes. The resulting model can naturally reproduce the observed values of ${B}_{d}^{0}\ensuremath{-}{\overline{B}}_{d}^{0}$ mixing, where the original model had failed by 8 orders of magnitude. Thus, the model is viable from the viewpoint of low-energy phenomenology. In the case of ${Z}^{0}$ physics, however, we see that the model makes distinctive predictions for some of the ${Z}^{0}\ensuremath{\rightarrow}f\overline{f}$ partial widths due to the nonstandard couplings of the fermion $f$. The recent measurements of these partial widths from CERN LEP seem to clearly rule out this model. Indeed the precision measurement of the ${Z}^{0}\ensuremath{\rightarrow}b\overline{b}$ partial width along with the known properties of $b$ decay seems to rule out any topless model.