A fourth generation could provide, within SUSY, a solution to baryogenesis at the EW scale. It is allowed by precision measurements. Available data from Tevatron already restrict the allowed domain of parameters for the new quarks and the Higgs boson. There are some indications from b->s transitions which could be interpreted within an extension of the CKM matrix to 4x4, in particular CPV in the Bs time-dependence for the J/Psi-Phi mode observed at Tevatron. If confirmed with more data the 4MSSM interpretation predicts a very interesting scenario for LHC and a TeV LC.
We analyze the power of the Tevatron dataset to exclude or discover fourth generation neutrinos. In a general framework, one can have mixed left- and right-handed neutrinos, with Dirac and Majorana neutrinos as extreme cases. We demonstrate that a single Tevatron experiment can make powerful statements across the entire mixing space, extending LEP's mass limits of 60-80 GeV up to 150-175 GeV, depending on the mixing.
If next generations of heavy quarks and leptons exist within the standard model (SM), they can manifest themselves in Higgs boson production at the Tevatron and the LHC, before being actually observed. This generation leads to an increase of the Higgs boson production cross section via gluon fusion at hadron colliders by a factor 6-9. So, the study of this process at the Tevatron and LHC can finally fix the number of generations in the SM. Using the $WW^*$ Higgs boson decay channel, the studies at the upgraded Tevatron will answer the question about the next generation for mass values 135 GeV …
In scenarios with relatively light down squarks, motivated, e.g., by SO(10) D terms, jets + missing $E_T$ signals can be observed at the luminosity upgraded Tevatron even if the squarks are much heavier than the gluinos and the common gaugino mass ($M_{1/2}$) at $M_G$ lies above the LEP allowed lower bound. In the conventional mSUGRA model with heavy squarks practically no signal is expected in this channel. The possiblity of distinguishing between various SUGRA motivated scenarios by exploiting the missing $E_T$ and jet $p_T$ distributions, opposite sign dileptons + jets + missing $E_T$ event…
An R-parity violating SUSY model with lepton-number violating couplings $λ'_{i33}$, i=2,3 can generate a neutrino mass spectrum that explains the recent results from neutrino oscillation experiments. These R-parity violating couplings lead to a clean signal with at least one isolated lepton and at least three tagged $b$ jets that is accessible in chargino and neutralino production at the Tevatron collider. This signature can be probed at $3 σ$ up to $m_{1/2} = 230$ GeV (320 GeV) with an integrated luminosity of $2 fb^{-1}$ ($30 fb^{-1}$).
Recent Tevatron exclusion interval of the masses of Higgs boson considerably reduces in case of the light quasistable fourth generation neutral lepton.
The excess of high $Q^2$ events at HERA reported in the early 1997 by H1 and ZEUS collaborations has become the subject of extensive studies in the framework of several models related to new physics. Here we concentrate on the most promising, from our point of view, model describing HERA anomaly. We update our previous analysis and take into account new HERA statistics of the 1997 year. HERA events are considered within the R-parity broken SUSY model for a specific scenario with several non-zero couplings. R-parity broken SUSY with several non-zero couplings could explain both high $Q^2 e^+ + …
In minimal supergravity based supersymmetry models the charged sleptons as well as the sneutrinos may be lighter than the squarks. In such light slepton scenario the search for lighter stop squark has been investigated in the dilepton + missing $p_T(\missingpt)$ +jets ($\ge 1$) channel at Tevatron. In this scenario semileptonic decay of lighter stop squark has been considered via off shell and on shell charginos. In the latter case the chargino undergoes pure leptonic 2-body decay. We observe that for some favourable region of the MSSM parameter space one can probe lighter stop squark mass upt…
The Higgs boson search has shifted from LEP2 to the Tevatron and will subsequently move to the LHC. The current limits from the Tevatron and the prospective sensitivities at the LHC are often interpreted in specific MSSM scenarios. For heavy Higgs boson production and subsequent decay into b \bar b or tau^+ tau^-, the present Tevatron data allow to set limits in the M_A-tan_beta plane for small M_A and large tan_beta values. Similar channels have been explored for the LHC, where the discovery reach extends to higher values of M_A and smaller tan_beta. Searches for MSSM charged Higgs bosons, pr…
We study extensions of the Minimal Supersymmetric Standard Model (MSSM) with new degrees of freedom that couple sizably to the MSSM Higgs sector and lie in the TeV range. After integrating out the physics at the TeV scale, the resulting Higgs spectrum can significantly differ from typical supersymmetric scenarios, thereby providing a window Beyond the MSSM (BMSSM). Taking into account current LEP and Tevatron constraints, we perform an in-depth analysis of the Higgs collider phenomenology and explore distinctive characteristics of our scenario with respect to both the Standard Model and the MS…
Searches for SUSY particles are the main physics focus of the ongoing Run IIa of the Tevatron. LEP results have constrained heavily the Minimal Supersymmetric Standard Model. In this paper the results obtained at LEP and the Tevatron Run I are analysed within two consistent scenarios: the gravity-mediated MSSM framework and the minimal SUGRA scenario. In these frameworks limits much beyond the kinematic reach of LEP are set, and the allowed mass range for particles which are not directly observable at LEP is explored. These results can be used to evaluate searches at the Tevatron Run II. Both …
The favoured R-parity violating SUSY scenarios for the anomalous HERA events correspond to top and charm squark production via the $λ'_{131}$ and $λ'_{121}$ couplings. In both cases the corresponding electronic branching fractions of the squarks are expected to be $\ll 1$. Consequently the canonical leptoquark signature is incapable of probing these scenarios at the 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.
The latest electroweak precission data allow the existence of additional chiral generations in the standard model. We study the influence of extra generations on the production of SM Higgs boson at hadron colliders. Due to the enhancement of the gluon fusion channel, the ``golden mode'' becomes more promising even at upgraded Tevatron. Furthermore, the formation of the fourth family quarkonia with the subsequent $η_{4}\to ZH$ decay introduces additional tool for the investigation of the Higgs boson properties.
This contribution contains a brief review of several scenarios for physics beyond the Standard Model at the energy scales accessible to experiments at the Tevatron and the LHC, focusing on their experimental signatures.
The Tevatron collaborations have searched for associated production of charginos and neutralinos via trilepton final states. No events above the Standard Model prediction were observed. We employ these results to put stringent bounds on R-parity violating models with a right-handed scalar electron as the lightest supersymmetric particle. We work in the framework of lepton number violating minimal supergravity. We find that within these models the complete parameter space consistent with the anomalous magnetic moment of the muon can be excluded at 90% confidence level. We also give prospects fo…
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…
Existence of the fourth family follows from the basics of the Standard Model and the actual mass spectrum of the third family fermions. We discuss possible manifestations of the fourth SM family at existing and future colliders. The LHC and Tevatron potentials to discover the fourth SM family have been compared. The scenario with dominance of the anomalous decay modes of the fourth family quarks has been considered in details.
We propose a new scenario in which the dominant signal for supersymmetry at the Tevatron are the events having two or three $τ$ leptons with high $p_T$ accompanied by large missing transverse energy. This signal is very different from the multijet or multileptons (involving $e$ and/or $μ$ only) or the photonic signals that have been extensively investigated both theoretically and experimentally. A large region of the GMSB parameter space with the lighter stau as the NLSP allow this possibility. Such a signal may be present in the past Tevatron data to be analyzed.
The dimuon and dielectron data from the Tevatron $\bar pp$ collider are used to probe for heavy quarks, which decay dominantly via flavour changing neutral current. 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 lefthanded quark doublet of the fourth generation.
We consider the scenarios of the GMSB models in which the dominant signal for supersymmetry at the Tevatron are the events having two or three $τ$ leptons with high $p_T$ accompanied by large missing transverse energy. This signal is very different from the multijet or multileptons (involving $e$ and/or $μ$ only) in the usual supergravity models or the photonic signals in the GMSB models (where the lightest neutralino is the next to lightest supersymmetric particle (NLSP)). The parameter space where the lighter stau is the NLSP allows this possibility. We find that such a signal could be obser…
Within the paradigm of warped extra dimensions, third generation quarks are expected to be the most sensitive to effects beyond the Standard Model. The anomalies observed at the LEP and Tevatron colliders in the forward-backward asymmetries of the bottom (A_FB^b) and top (A_FB^t) quarks can thus be seen as early signatures of warped extra-dimensional scenarios. We propose a realization of such a scenario, with a gauge custodial symmetry in the bulk, which allows to address simultaneously the A_FB^b anomaly and the discrepancies observed recently on A_FB^t at high top quark rapidities and ttbar…
Because of their Yukawa interactions, third generation squarks may be substantially lighter than those of the first two generations. Assuming that $\tb_1 \to b\tz_1$ and $\tz_1$ escapes experimental detection, we show that experiments at the Main Injector upgrade (integrated luminosity of $2 fb^{-1}$) of the Tevatron should be sensitive to $b$-squark masses up to 210 GeV for $m_{\tz_1} \leq 120$ GeV. For integrated luminosities of $10 fb^{-1}$ (25 $fb^{-1}$) the sbottom mass reach increases by 20 GeV (35 GeV). If the channel $\tb_1 \to b\tz_2$ is also accessible, the reach becomes model-depend…
The effects of light, long-lived gluinos on $2\to 2$ processes at hadron colliders are examined. Such particles can mediate single squark resonant production via $q\glu\to\sq\to q\glu$ which would significantly modify the dijet data sample. We find that squark masses in the range $130<m_{\tilde q}< 694, 595, 573$ GeV are excluded for gluino masses of $0.4, 1.3, 5.0$ GeV from existing UA2 and Tevatron data on dijet bump searches and angular distributions. Run II of the Tevatron has the capability of excluding this scenario for squark masses up to $\sim 1$ TeV.
We examine the possibility that a new strong interaction is accessible to the Tevatron and the LHC. In an effective theory approach, we consider a scenario with a new color-octet interaction with strong couplings to the top quark, as well as the presence of a strongly coupled fourth-generation which could be responsible for electroweak symmetry breaking. We apply several constraints, including the ones from flavor physics. We study the phenomenology of the resulting parameter space at the Tevatron, focusing on the the forward-backward asymmetry in top pair production, as well as in the product…
We provide a detailed analysis of the supersymmetric tri-lepton signals for sparticle searches at the Tevatron in the minimal supersymmetric standard model with general CP-violating phases but without flavor mixing among sfermions of different generation. The stringent experimental constraints on the CP-violating phases from the electron and neutron electric dipole moments are included in the analysis for two exemplary scenarios of the SUSY parameters; one with decoupled first two generation sfermions and the other with non-decoupled sfermions. In both scenarios, the production cross section a…
We study in detail the model by Isidori and Kamenik that is claimed to explain the top quark forward-backward asymmetry at Tevatron, provide GeV-scale dark matter (DM), and possibly improve the agreement between data and theory in Tevatron W+jj events. We compute the DM thermal relic density, the spin-independent DM-nucleon scattering cross section, and the cosmic microwave background constraints on both Dirac and Majorana neutralino DM in the parameter space that explains the top asymmetry. A stable light neutralino is not allowed unless the local DM density is 3-4 times smaller than expected…
In this letter, we investigate the production of light dark matter particles at LHC in light of the model (N = 2 SUSY inspired) proposed in Ref. [1] and demonstrate that they will be copiously produced if the colored messengers Fq are lighter than 1 TeV. We expect up to a million events if the Fq mass is about 500 GeV, assuming a ~1 inverse fb luminosity. In addition, we show that, even if the Fq mass is above a few TeV, searches for Fq production at LHC are promising because a kinematical signature can be used to separate the signal from background. This signature is similar to that expected …
In supersymmetric models, Winos, partners of the SU(2) gauge bosons, may be the lightest supersymmetric particles (LSPs). For generic parameters, charged and neutral Winos are highly degenerate. Charged Winos travel macroscopic distances, but can decay to neutral Winos and extremely soft leptons or pions before reaching the muon chambers, thereby circumventing conventional trigger requirements based on energetic decay products or muon chamber hits. However, these charginos are detectable, and can be triggered on when produced in association with jets. In addition, we propose a new trigger for …
We present the first constraints on the parameter space of $SU(5)\times U(1)$ supergravity (in both no-scale and dilaton scenarios) which arise from the recently announced limits on trilepton searches at the Tevatron. The trilepton rate has been calculated for those points in parameter space which satisfy not only the minimal theoretical and experimental LEP constraints, but also the {\em combined} effect of the following indirect experimental constraints: (i) the CLEO limits on the $b\to sγ$ rate, (ii) the long-standing limit on the anomalous magnetic moment of the muon, (iii) the non-observa…
Limits are derived on models with extended Higgs sectors, including the Minimal Supersymmetric Standard Model (MSSM), by exploiting the data on $τ^+ τ^- + $ 2 jets final states, used by the CDF collaboration to place limits on third generation leptoquarks. The main observation here is that both leptoquark production and associated $b \bar{b}$ Higgs production can lead to $b \bar{b} τ^+ τ^-$ final states.
We evaluate the supersymmetric (SUSY) electroweak corrections to the effect of parity nonconservation in $q {\bar q} \to t {\bar t}$ production at the Fermilab Tevatron predicted by the Minimal Supersymmetric Model (MSSM). We find that the parity nonconserving asymmetry from the SUSY electroweak and SUSY Yukawa loop corrections predicted by the minimal supergravity (mSUGRA) model and the MSSM models with scenarios motivated by current data is about one percent. It will be challenging to observe such a small asymmetry at the Tevatron with 10 fb^{-1} of luminosity. It could however be observable…
We determine the prospects for finding dark matter at the Tevatron and LHC through the production of exotic 4th generation quarks T' that decay through T' \to t X, where X is dark matter. The resulting signal of t \bar{t} + \met has not previously been considered in searches for 4th generation quarks, but there are both general and specific dark matter motivations for this signal, and with slight modifications, this analysis applies to any scenario where invisible particles are produced in association with top quarks. Current direct and indirect bounds on such exotic quarks restrict their mass…
How light can the stop be given current experimental constraints? Can it still be lighter than the top? In this paper, we study this and related questions in the context of gauge-mediated supersymmetry breaking, where a stop NLSP decays into a W, b and gravitino. Focusing on the case of prompt decays, we simulate several existing Tevatron and LHC analyses that would be sensitive to this scenario, and find that they allow the stop to be as light as 150 GeV, mostly due to the large top production background. With more data, the existing LHC analyses will be able to push the limit up to at least …
The dimuon plus dijet signal is analyzed in the top squark pair production at Tevatron Run-II experiment and the total event rate is compared with the existing dimuon data. This comparison rules out top squark mass upto 188(104) GeV for the branching fraction 100%(50%) of top squark decay into the muon plus quark via lepton number violating coupling. Interpretation of this limit in the framework of R-parity violating(RPV) SUSY model puts limit on relevant RPV coupling for a given top squark mass and other supersymmetric model parameters. If $\MST \lsim 180$ GeV we found that the RPV couplings …
We explore the room for possible deviations from the Standard Model (SM) Higgs boson coupling structure in a systematic study of Higgs coupling scale factor benchmark scenarios using the latest signal rate measurements from the Tevatron and LHC experiments. We employ chi-squared fits performed with HiggsSignals, which takes into account detailed information on signal efficiencies and major correlations of theoretical and experimental uncertainties. All considered scenarios allow for additional non-standard Higgs boson decay modes, and various assumptions for constraining the total decay width …
We analyse the impact of LHC and Tevatron Higgs data on the viability of the Standard Model with a sequential fourth generation (SM4), assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal cross sections of pp -> H -> gamma gamma,ZZ*,WW* at the LHC, to p pbar -> VH -> V b bbar (V = W, Z) at the Tevatron and to the electroweak precision observables. Fixing the mass of the fourth generation down-type quark b' to 600 GeV we find best-fit values of m_t' = 632 GeV, m_l4 = 113.6 GeV and m_nu4 = 58.0 GeV for the other fourth-generation fermion masse…
We investigate the collider phenomenology of gluino-bino co-annihilation scenario both at the Tevatron and 7 TeV LHC. This scenario can be realized, for example, in a class of realistic supersymmetric models with non-universal gaugino masses and t-b-τYukawa unification. The NLSP gluino and LSP bino should be nearly degenerate in mass, so that the typical gluino search channels involving leptons or hard jets are not available. Consequently, the gluino can be lighter than various bounds on its mass from direct searches. We propose a new search for NLSP gluino involving multi-b final states, aris…
We study unconventional decays of the top-quark and the top-squark in the framework of SUSY models with broken R-parity. The model under study is the MSSM with an additional bilinear term that breaks R-parity. In this model the top-squark behaves similar to a third generation leptoquark. We demonstrate that existing Tevatron data on the top give rise to restrictions on the SUSY parameter space. In particular, we focus on scenarios where the tau-neutrino mass is smaller than 1 eV. We give an exclusion plot derived from the leptoquark searches at Tevatron.
In the minimal anomaly-mediated supersymmetry breaking (AMSB) model, a universal contribution $m_{0}$ to all the scalar masses is introduced in order to avoid the negative slepton mass problem. The Higgs spectrum and couplings are determined by four parameters: $m_{\rm aux}, m_{0}, \tanβ$ and sign ($μ$). The sign of $μ$ affects $m_A$ at large $\tanβ$ and $m_h$ at small $\tanβ$. The CP-odd Higgs mass $m_A$ is usually much larger than ${m}_{Z}$ and the lightest CP-even Higgs is simply analogous to the one in the standard model. The current and future Higgs searches in LEP, Tevatron and LHC provi…
We survey strategies generally employed for SUSY discovery at colliders and then discuss how these may have to be altered for SUSY searches at the Tevatron if $\tanβ$ is large. We also discuss the reach of the Tevatron and the LHC in gauge-mediated SUSY breaking scenarios, assuming that the NLSP decays into photons. Finally, we briefly recapitulate measurements (which serve to guide us to the underlying theory) that might be possible at future colliders if supersymmetry is discovered.
A long-standing discrepancy between the bottom-quark production cross section and predictions of perturbative quantum chromodynamics is addressed. We show that pair production of light gluinos, of mass 12 to 16 GeV, with two-body decays into bottom quarks and light bottom squarks, yields a bottom-quark production rate in agreement with hadron collider data. We examine constraints on this scenario from low-energy data and make predictions that may be tested at the next run of the Fermilab Tevatron Collider.
The search for the effects of heavy fermions in the extension of the Standard Model with a fourth generation is part of the experimental program of the Tevatron and LHC experiments. Besides being directly produced, these states affect drastically the production and decay properties of the Higgs boson. In this note, we first reemphasize the known fact that in the case of a light and long-lived fourth neutrino, the present collider searches do not permit to exclude a Higgs boson with a mass below the WW threshold. In a second step, we show that the recent results from the ATLAS and CMS collabora…
We consider the impact of a 4th generation on Higgs to $γγ$ and $WW,ZZ$ signals and demonstrate that the Tevatron and LHC have essentially eliminated the possibility of a 4th generation if the Higgs is SM-like and has mass below 200 GeV. We also show that the absence of enhanced Higgs signals in current data sets in the $γγ$ and $WW,ZZ$ final states can strongly constrain the possibility of a 4th generation in two-Higgs-doublet models of type II, including the MSSM.
We show that, if a fourth generation is discovered at the Tevatron or LHC, one could study CP violation in b' \to s decays. Asymmetries could reach 30% for b'\to sZ for m_{b'} \lesssim 350 GeV, while it could be greater than 50% for b'\to sγand extend to higher m_{b'}. Branching ratios are 10^{-3}--10^{-5}, and CPV measurement requires tagging. Once measured, however, the CPV phase can be extracted with little theoretical uncertainty.
The Standard Model predicts a very small CP violation phase $\sin2Φ^{\rm SM}_{B_s} \simeq -0.04$%= \arg M_{12} \simeq \arg\,(V^*_{ts}V_{tb})^2$ in $B_s$--$\bar B_s$ mixing. %, i.e. of order $λ^2η$. Any finite value of $Φ_{B_s}$ measured at the Tevatron would imply New Physics. With recent hints for finite $\sin2Φ_{B_s}$, % have appeared from CDF and DØ\, experiments at the Tevatron, we reconsider the possibility of a 4th generation. As recent direct search bounds have become considerably heavier than 300 GeV, we take the $t'$ mass to be near the unitarity bound of 500 GeV. Combining the measur…
We propose an interpretation of the diboson excess recently observed by the ATLAS and CMS collaborations in terms of Kaluza-Klein excitations of electroweak gauge bosons stemming from a realization of a warped extra-dimensional model that is protected by a custodial symmetry. Besides accounting for the LHC diboson data, this scenario also leads to an explanation of the anomalies that have been observed in the measurements of the forward-backward asymmetries for bottom quarks at LEP and top quarks at the Tevatron.
We explore beyond Standard Model (bSM) physics signatures in the $l+jets$ channel of $t\overline{t}$ pair production process at the Tevatron and the LHC. We study the effects of bSM physics scenarios on the top quark polarization and on the kinematics of the decay leptons. To this end, we construct asymmetries using the lepton energy and angular distributions. Further, we find their correlations with the top polarization, net charge asymmetry and top forward backward asymmetry. We show that used together, these observables can help discriminate effectively between SM and different bSM scenario…
We present updated NLO predictions for the electroweak t-channel production of heavy quarks at the Tevatron and at the LHC. We consider production of single top and fourth generation t' starting from both 2 to 2 and 2 to 3 Born processes. Predictions for tb' and t'b' cross sections at NLO are also given for the first time. A thorough study of the theoretical uncertainties coming from parton distribution functions, renormalisation and factorisation scale dependence and heavy quark masses is performed.
The Higgs and some of the Standard Model superpartners may have been copiously produced at LEP and the Tevatron without being detected. We study a novel scenario of this type in which the Higgs decays predominantly into a light hidden sector either directly or through light SUSY states. Subsequent cascades increase the multiplicity of hidden sector particles which, after decaying back into the Standard Model, appear in the detector as clusters of collimated leptons known as lepton jets. We identify the relevant collider observables that characterize this scenario, and study a wide range of LEP…
Spectra for the emission of charged leptons from evaporating hot-spots of preconfining phase in SU(2) Yang-Mills thermodynamics are computed. Specifically, we consider charged single and dileptons with their spectra being functions of energy and invariant mass, respectively. In the former case, our results relate to narrow and correlated electron and positron peaks measured in supercritical heavy-ion collisions performed at GSI in the 1980ies. In the latter case, we point out how strongly the spectra depend on typical kinematic cuts (CDF analysis of Tevatron Run II data). We also propose a sce…
We perform a multi-parameter global analysis of all data available till date from the ATLAS, CMS and Tevatron experiments, on the signals of a Higgs boson, to investigate how much scope exists for departure from the standard model prediction. We adopt a very general and model-independent scenario, where separate deviations from standard model values are possible for couplings of the observed scalar with up-and down-type fermions, W-and Z-boson pairs, as well as gluon and photon pair effective interactions. An arbitrary phase in the coupling with the top-pair, and the provision for an invisible…
We perform a phenomenological fit to all ATLAS, CMS, CDF and D0 Higgs boson data available after Moriond 2012. We allow all Higgs boson branching fractions, its couplings to standard model particles, as well as to an hypothetical invisible sector to vary freely, and determine their current favourite values. The standard model Higgs boson with a mass 125 GeV correctly predicts the average observed rate and provides an acceptable global fit to data. However, better fits are obtained by non-standard scenarios that reproduce anomalies in the present data (more γγ and less WW signals than expected)…
A measurement of the branching ratio for the rare decay mode B_s->mu mu at the Tevatron is an opportunity to test various supersymmetric scenarios. We investigate the prospects for studying this mode in Run II and estimate that CDF would be sensitive to this decay for a branching ratio > 1.2 \times 10^{-8} with 15 \invfb (or, if a similar analysis holds for D0, >6.5\times 10^{-9} for the combined data). We calculate the branching ratio in minimal supergravity (mSUGRA) parameter space, and find that tanβ> 30 can be probed. (This mSUGRA parameter space cannot be probed by direct production of SU…
We study and constrain the parameter space of the vector color-octet model from observed data at Tevatron by studying top quark pair production and associated observables afbt and spin-correlation. In particular we study invariant mass and rapidity dependence of afbt at Tevatron. In addition to FC couplings we extend our study to include FV coupling involving first & third generation quarks for both these processes. In order to ensure that we remain within the constraints imposed by LHC data, we analyze the charge asymmetry, p_T spectrum & invariant mass in t\bar t production data at LHC. The …
In theories with the standard model gauge bosons propagating in inverse-TeV-size extra dimensions, their Kaluza-Klein states interact with the rest of the SM particles confined to the 3-brane. We look for possible signals for this interaction in the present high-energy collider data, and estimate the sensitivity offered by the next generation of collider experiments. Based on the present data from the LEP 2, Tevatron, and HERA experiments, we set a lower limit on the extra dimension compactification scale Mc > 6.8 TeV at the 95% confidence level (dominated by the LEP 2 results) and quote expec…
We constrain the masses of scalar-tops (stop) by analyzing the new precision Tevatron measurement of the W-boson mass and the LHC/Tevatron indications of a Higgs boson of mass 125.5+-1 GeV. Our study adopts Natural SUSY with low fine-tuning, which has multi-TeV first and second generation squarks and a light Higgsino mixing parameter mu=150 GeV. An effective Lagrangian calculation is made of mh to 3-loops using the H3m program with weak scale SUSY parameters obtained from RGE evolution from the GUT scale in the Natural SUSY scenario. The SUSY radiative corrections to the Higgs mass imply maxim…
