The scalars from the topcolor scenario and the spin correlations of the top pair production at the LHC

The topcolor scenario predicts the existences of some new scalars. In this paper, we consider the contributions of these new particles to the observables, which are related to the top quark pair ($t\bar{t}$) production at the LHC. It is found that these new particles can generate significant corrections to the $t\bar{t}$ production cross section and the $t\bar{t}$ spin correlations.Comment: 23 pages, 4 figures; discussions and references added; agrees with published versio

Flux quantization and superfluid weight in doped antiferromagnets

Doped antiferromagnets, described by a t-t'-J model and a suitable 1/N expansion, exhibit a metallic phase-modulated antiferromagnetic ground state close to half-filling. Here we demonstrate that the energy of latter state is an even periodic function of the external magnetic flux threading the square lattice in an Aharonov-Bohm geometry. The period is equal to the flux quantum $\Phi_{0}=2\pi\hbar c/q$ entering the Peierls phase factor of the hopping matrix elements. Thus flux quantization and a concomitant finite value of superfluid weight D_s occur along with metallic antiferromagnetism. We argue that in the context of the present effective model, whereby carriers are treated as hard-core bosons, the charge q in the associated flux quantum might be set equal to 2e. Finally, the superconducting transition temperature T_c is related to D_s linearly, in accordance to the generic Kosterlitz-Thouless type of transition in a two-dimensional system, signaling the coherence of the phase fluctuations of the condensate. The calculated dependence of T_c on hole concentration is qualitatively similar to that observed in the high-temperature superconducting cuprates.Comment: 5 pages, 2 figures, to be published in J. Phys. Condens. Matte

Lattice determination of the critical point of QCD at finite T and \mu

Based on universal arguments it is believed that there is a critical point (E) in QCD on the temperature (T) versus chemical potential (\mu) plane, which is of extreme importance for heavy-ion experiments. Using finite size scaling and a recently proposed lattice method to study QCD at finite \mu we determine the location of E in QCD with n_f=2+1 dynamical staggered quarks with semi-realistic masses on $L_t=4$ lattices. Our result is T_E=160 \pm 3.5 MeV and \mu_E= 725 \pm 35 MeV. For the critical temperature at \mu=0 we obtained T_c=172 \pm 3 MeV.Comment: misprints corrected, version to appear in JHE

The Higgs intense--coupling regime in constrained SUSY models and its astrophysical implications

We analyze the Higgs intense--coupling regime, in which all Higgs particles of the Minimal Supersymmetric Standard Model are light with masses of the same order and the value of \tb the ratio of vacuum expectation values of the two Higgs fields is large, in the framework of Supergravity scenarios with non--universal soft Supersymmetry breaking scalar masses in the Higgs sector. In particular, we calculate the relic density abundance of the lightest neutralino candidate for cold dark matter and the rates in direct and indirect detection at present and future experiments. We first show that while in the mSUGRA model this regime is disfavored by present data, there are regions in the parameter space of models with non--universal Higgs masses where it can occur. We then show that because of the large value of $\tan\beta$ and the relatively low values of the neutral Higgs boson masses, the cross section for neutralino--nucleon scattering is strongly enhanced in this regime and would allow for the observation of a signal in direct detection experiments such as CDMS--Soudan. The expected sensitivity of gamma--ray detectors like GLAST might be also sufficient to observe the annihilation of neutralinos in such a regime.Comment: 19 pages, 5 figure

VerdictDB: Universalizing Approximate Query Processing

Despite 25 years of research in academia, approximate query processing (AQP) has had little industrial adoption. One of the major causes of this slow adoption is the reluctance of traditional vendors to make radical changes to their legacy codebases, and the preoccupation of newer vendors (e.g., SQL-on-Hadoop products) with implementing standard features. Additionally, the few AQP engines that are available are each tied to a specific platform and require users to completely abandon their existing databases---an unrealistic expectation given the infancy of the AQP technology. Therefore, we argue that a universal solution is needed: a database-agnostic approximation engine that will widen the reach of this emerging technology across various platforms. Our proposal, called VerdictDB, uses a middleware architecture that requires no changes to the backend database, and thus, can work with all off-the-shelf engines. Operating at the driver-level, VerdictDB intercepts analytical queries issued to the database and rewrites them into another query that, if executed by any standard relational engine, will yield sufficient information for computing an approximate answer. VerdictDB uses the returned result set to compute an approximate answer and error estimates, which are then passed on to the user or application. However, lack of access to the query execution layer introduces significant challenges in terms of generality, correctness, and efficiency. This paper shows how VerdictDB overcomes these challenges and delivers up to 171$\times$ speedup (18.45$\times$ on average) for a variety of existing engines, such as Impala, Spark SQL, and Amazon Redshift, while incurring less than 2.6% relative error. VerdictDB is open-sourced under Apache License.Comment: Extended technical report of the paper that appeared in Proceedings of the 2018 International Conference on Management of Data, pp. 1461-1476. ACM, 201

Lattice supersymmetry, superfields and renormalization

We study Euclidean lattice formulations of non-gauge supersymmetric models with up to four supercharges in various dimensions. We formulate the conditions under which the interacting lattice theory can exactly preserve one or more nilpotent anticommuting supersymmetries. We introduce a superfield formalism, which allows the enumeration of all possible lattice supersymmetry invariants. We use it to discuss the formulation of Q-exact lattice actions and their renormalization in a general manner. In some examples, one exact supersymmetry guarantees finiteness of the continuum limit of the lattice theory. As a consequence, we show that the desired quantum continuum limit is obtained without fine tuning for these models. Finally, we discuss the implications and possible further applications of our results to the study of gauge and non-gauge models.Comment: 44 pages, 1 figur

The Highest Energy Neutrinos

Measurements of the arrival directions of cosmic rays have not revealed their sources. High energy neutrino telescopes attempt to resolve the problem by detecting neutrinos whose directions are not scrambled by magnetic fields. The key issue is whether the neutrino flux produced in cosmic ray accelerators is detectable. It is believed that the answer is affirmative, both for the galactic and extragalactic sources, provided the detector has kilometer-scale dimensions. We revisit the case for kilometer-scale neutrino detectors in a model-independent way by focussing on the energetics of the sources. The real breakthrough though has not been on the theory but on the technology front: the considerable technical hurdles to build such detectors have been overcome. Where extragalactic cosmic rays are concerned an alternative method to probe the accelerators consists in studying the arrival directions of neutrinos produced in interactions with the microwave background near the source, i.e. within a GZK radius. Their flux is calculable within large ambiguities but, in any case, low. It is therefore likely that detectors that are larger yet by several orders of magnitudes are required. These exploit novel techniques, such as detecting the secondary radiation at radio wavelengths emitted by neutrino induced showers.Comment: 16 pages, pdflatex, 7 jpg figures, ICRC style files included. Highlight talk presented at the 30th International Cosmic Ray Conference, Merida, Mexico, 200

A tentative Replica Study of the Glass Transition

We propose a method to study quantitatively the glass transition in a system of interacting particles. In spite of the absence of any quenched disorder, we introduce a replicated version of the hypernetted chain equations. The solution of these equations, for hard or soft spheres, signals a transition to the glass phase. However the predicted value of the energy and specific heat in the glass phase are wrong, calling for an improvement of this method.Comment: 9 pages, four postcript figures attache

Mixed Wino Dark Matter: Consequences for Direct, Indirect and Collider Detection

In supersymmetric models with gravity-mediated SUSY breaking and gaugino mass unification, the predicted relic abundance of neutralinos usually exceeds the strict limits imposed by the WMAP collaboration. One way to obtain the correct relic abundance is to abandon gaugino mass universality and allow a mixed wino-bino lightest SUSY particle (LSP). The enhanced annihilation and scattering cross sections of mixed wino dark matter (MWDM) compared to bino dark matter lead to enhanced rates for direct dark matter detection, as well as for indirect detection at neutrino telescopes and for detection of dark matter annihilation products in the galactic halo. For collider experiments, MWDM leads to a reduced but significant mass gap between the lightest neutralinos so that chi_2^0 two-body decay modes are usually closed. This means that dilepton mass edges-- the starting point for cascade decay reconstruction at the CERN LHC-- should be accessible over almost all of parameter space. Measurement of the m_{\tz_2}-m_{\tz_1} mass gap at LHC plus various sparticle masses and cross sections as a function of beam polarization at the International Linear Collider (ILC) would pinpoint MWDM as the dominant component of dark matter in the universe.Comment: 29 pages including 19 eps figure

Inflation on an Open Racetrack

We present a variant of warped D-brane inflation by incorporating multiple sets of holomorphically-embedded D7-branes involved in moduli stabilization with extent into a warped throat. The resultant D3-brane motion depends on the D7-brane configuration and the relative position of the D3-brane in these backgrounds. The non-perturbative moduli stabilization superpotential takes the racetrack form, but the additional D3-brane open string moduli dependence provides more flexibilities in model building. For concreteness, we consider D3-brane motion in the warped deformed conifold with the presence of multiple D7-branes, and derive the scalar potential valid for the entire throat. By explicit tuning of the microphysical parameters, we obtain inflationary trajectories near an inflection point for various D7-brane configurations. Moreover, the open racetrack potential admits approximate Minkowski vacua before uplifting. We demonstrate with a concrete D-brane inflation model where the Hubble scale during inflation can exceed the gravitino mass. Finally, the multiple sets of D7-branes present in this open racetrack setup also provides a mechanism to stabilize the D3-brane to metastable vacua in the intermediate region of the warped throat.Comment: 29 pages, 15 figures, pre-print number and references adde