118466159
Coupling extraction from off-shell cross sections
In this note, we present a novel method of extracting the couplings of a new heavy particle to the Standard Model states. Contrary to the usual discovery process which involves studying the on-shell production, we look at regions away from resonance to take advantage of the simple scaling of the cross-section with the couplings. We apply the procedure to the case of a heavy quark as an illustration.
119236521
Associated production of a KK-graviton with a Higgs boson via gluon fusion at the LHC
In order to solve the hierarchy problem, several extra-dimensional models have received considerable attention. We have considered a process where a Higgs boson is produced in association with a KK-graviton (GKK) at the LHC. At the leading order, this process occurs through the gluon fusion mechanism gg→hGKK via a quark loop. We compute the cross section and examine some features of this process in the ADD model. We find that the quark in the loop does not decouple in the large quark-mass limit just as in the case of gg→h process. We compute the cross section of this process for the case of the RS model also. We examine the feasibility of this process being observed at the LHC.
118392903
Probing color octet electrons at the LHC
Models with quark and lepton compositeness predict the existence of colored partners of the Standard Model leptons. In this paper we study the LHC phenomenology of a charged colored lepton partner, namely the color octet electron, $e_8$ in an effective theory framework. We explore various mechanisms for resonant production of $e_8$'s. With the pair production channel the 14 TeV LHC can probe $e_8$'s with masses up to 2.5 TeV (2.8 TeV) with 100 fb$^{-1}$ (300 fb$^{-1}$) of integrated luminosity. A common feature in all the resonant production channels is the presence of two high $p_T$ electrons and at least one high $p_T$ jet in the final state. Using this feature, we implement a search method where the signal is a combination of pair and single production events. This method has potential to increase the LHC reach significantly. Using the combined signal we estimate the LHC discovery potential for the $e_8$'s. Our analysis shows that the LHC with 14 TeV center-of-mass energy and 100 fb$^{-1}$ (300 fb$^{-1}$) of integrated luminosity can probe $e_8$'s with masses up to 3.4 TeV (4 TeV) for the compositeness scale of 5 TeV.
55183340
Production of a KK-graviton in association with a boson via gluon fusion at the LHC
We discuss the processes where a KK-graviton ($G$) of the extra-dimensional models is produced in association with a color singlet boson via gluon fusion at the LHC. In particular, we consider the processes $gg \to h G$, $\gamma G$, $Z G$. These processes occur at one-loop through box and triangle diagrams. The cross-section for the process $gg \to \gamma G$ vanishes at the one-loop level. It can be understood by introducing the charge conjugation transformations of the KK-graviton. The processes $gg \to h G$, $Z G$ can be observed at the LHC if the KK-graviton and the Higgs boson exist with appropriate properties.
119291062
Effect of anomalous couplings on the associated production of a single top quark and a Higgs boson at the LHC
A bstractWe consider the production of a single top quark in association with a Higgs boson at the LHC. In particular, we compute the cross sections for the processes pp → thj, thb, thW , thjj, thjb, thW j, thW b in the presence of the anomalous W tb, W W h and tth couplings. We find that the anomalous W tb and tth couplings can enhance the cross sections significantly. We also analyze a few signatures and show that, if these couplings are indeed anomalous, then with enough data, one should be able to observe the production of the Higgs boson in association with single top quark.
53636995
LHC signatures of warped-space vectorlike quarks
A bstractWe study the LHC signatures of TeV scale vectorlike quarks b′, t′ and χ with electromagnetic charges −1/3, 2/3 and 5/3 that appear in many beyond the standard model (BSM) extensions. We consider warped extra-dimensional models and analyze the phenomenology of such vectorlike quarks that are the custodial partners of third generation quarks. In addition to the usually studied pair-production channels which depend on the strong coupling, we put equal emphasis on single production channels that depend on electroweak couplings and on electroweak symmetry breaking induced mixing effects between the heavy vectorlike quarks and standard model quarks. We identify new promising gg-initiated pair and single production channels and find the luminosity required for discovering these states at the LHC. For these channels, we propose a cut that allows one to extract the relevant electroweak couplings. Although the motivation is from warped models, we present many of our results model-independently.
5141632
Ordinary atom mirror atom bound states: A New window on the mirror world
Mirror symmetry is a plausible candidate for a fundamental symmetry of particle interactions which can be exactly conserved if a set of mirror particles exist. The properties of the mirror particles seem to provide an excellent candidate to explain the inferred dark matter of the Universe and might also be responsible for a variety of other puzzles in particle physics, astrophysics, meteoritics and planetary science. One such puzzle\char22{}the orthopositronium lifetime problem\char22{}can be explained if there is a small kinetic mixing of ordinary and mirror photons. We show that this kinetic mixing implies the existence of ordinary atom\char21{}mirror-atom bound states with interesting terrestrial and astrophysical implications. We suggest that sensitive mass spectroscopic studies of ordinary samples containing heavy elements such as lead might reveal the presence of these bound states, as they would appear as anomalously heavy elements. In addition to the effects of single mirror atoms, collective effects from embedded fragments of mirror matter (such as mirror iron microparticles) are also possible. We speculate that such mirror matter fragments might explain a mysterious UV photon burst observed coming from a laser irradiated lead target in a recent experiment.
118559327
Constraining large‐scale H i bias using redshifted 21‐cm signal from the post‐reionization epoch
In the absence of complex astrophysical processes that characterize the reionization era, the 21-cm emission from neutral hydrogen (H i) in the post-reionization epoch is believed to be an excellent tracer of the underlying dark matter distribution. Assuming a background cosmology, it is modelled through (i) a bias function b(k, z), which relates H i to the dark matter distribution and (ii) a mean neutral fraction () which sets its amplitude. In this paper, we investigate the nature of large-scale H i bias. The post-reionization H i is modelled using gravity only N-body simulations and a suitable prescription for assigning gas to the dark matter haloes. Using the simulated bias as the fiducial model for H i distribution at z≤ 4, we have generated a hypothetical data set for the 21-cm angular power spectrum (Cl) using a noise model based on parameters of an extended version of the Giant Metrewave Radio Telescope (GMRT). The binned Cl is assumed to be measured with S/N ≳ 4 in the range 400 ≤l≤ 8000 at a fiducial redshift z= 2.5. We explore the possibility of constraining b(k) using the principal component analysis on these simulated data. Our analysis shows that in the range 0.2 < k < 2 Mpc−1, the simulated data set cannot distinguish between models exhibiting different k-dependences, provided 1 ≲b(k) ≲ 2 which sets the 2σ limits. This justifies the use of linear bias model on large scales. The largely uncertain is treated as a free parameter resulting in degradation of the bias reconstruction. The given simulated data are found to constrain the fiducial with an accuracy of ∼4 per cent (2σ error). The method outlined here could be successfully implemented on future observational data sets to constrain b(k, z) and and thereby enhance our understanding of the low-redshift Universe.
2081953
Have mirror micrometeorites been detected
Slow-moving $(v\ensuremath{\sim}15\mathrm{k}\mathrm{m}/\mathrm{s})$ ``dark matter particles'' have allegedly been discovered in a recent experiment. We explore the possibility that these slow moving dark matter particles are small mirror matter dust particles originating from our solar system. Ways of further testing our hypothesis, including the possibility of observing these dust particles in cryogenic detectors such as NAUTILUS, are also discussed.
14009133
Detecting mirror matter on Earth via its thermal imprint on ordinary matter
Mirror matter type dark matter can exist on the Earth's surface, potentially in enhanced concentrations at various anomalous impact sites. Mirror matter fragments can draw in heat from the ordinary matter environment, radiate mirror photons and thereby cool the surrounding ordinary matter. We quantify this effect and suggest that it could be used to help locate mirror matter deposits. This method, together with the centrifuge technique, seems to provide the most promising means to experimentally detect mirror matter type dark matter in the Earth.
16700064
Detecting Dark Matter using Centrifuging Techniques
Abstract A new and inexpensive technique for detecting self interacting dark matter in the form of small grains in bulk matter is proposed. Depending on the interactions with ordinary matter, dark matter grains in bulk matter may be isolated by using a centrifuge and using ordinary matter as a filter. The case of mirror matter interacting with ordinary matter via photon–mirror photon kinetic mixing provides a concrete example of this type of dark matter candidate.