Non-perturbative renormalisation and running of BSM four-quark operators in Nf=2 QCD

We perform a non-perturbative study of the scale-dependent renormalisation factors of a complete set of dimension-six four-fermion operators without power subtractions. The renormalisation-group (RG) running is determined in the continuum limit for a specific Schrödinger Functional (SF) renormalisation scheme in the framework of lattice QCD with two dynamical flavours (Nf= 2). The theory is regularised on a lattice with a plaquette Wilson action and O(a)-improved Wilson fermions. For one of these operators, the computation had been performed in Dimopoulos et al. (JHEP 0805, 065 (2008). arXiv:0712.2429); the present work completes the study for the rest of the operator basis, on the same simulations (configuration ensembles). The related weak matrix elements arise in several operator product expansions; in Δ F= 2 transitions they contain the QCD long-distance effects, including contributions from beyond-Standard Model (BSM) processes. Some of these operators mix under renormalisation and their RG-running is governed by anomalous dimension matrices. In Papinutto et al. (Eur Phys J C 77(6), 376 (2017). arXiv:1612.06461) the RG formalism for the operator basis has been worked out in full generality and the anomalous dimension matrix has been calculated in NLO perturbation theory. Here the discussion is extended to the matrix step-scaling functions, which are used in finite-size recursive techniques. We rely on these matrix-SSFs to obtain non-perturbative estimates of the operator anomalous dimensions for scales ranging from O(Λ QCD) to O(MW)

Flavor Changing Neutral Currents in a Realistic Composite Technicolor Model

We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral $B$, $D$, and $K$ meson systems.Comment: 16 pages, LaTeX + embedded PicTeX figures requiring prepictex, pictex, and postpictex inputs. HUTP.STY include

Discovering New Physics in the Decays of Black Holes

If the scale of quantum gravity is near a TeV, the LHC will be producing one black hole (BH) about every second, thus qualifying as a BH factory. With the Hawking temperature of a few hundred GeV, these rapidly evaporating BHs may produce new, undiscovered particles with masses ~100 GeV. The probability of producing a heavy particle in the decay depends on its mass only weakly, in contrast with the exponentially suppressed direct production. Furthemore, BH decays with at least one prompt charged lepton or photon correspond to the final states with low background. Using the Higgs boson as an example, we show that it may be found at the LHC on the first day of its operation, even with incomplete detectors.Comment: 4 pages, 3 figure

Comparison of LISA and Atom Interferometry for Gravitational Wave Astronomy in Space

One of the atom interferometer gravitational wave missions proposed by Dimopoulos et al.1 in 2008 was called AGIS-Sat. 2. It had a suggested gravitational wave sensitivity set by the atom state detection shot noise level that started at 1 mHz, was comparable to LISA sensitivity from 1 to about 20 mHz, and had better sensitivity from 20 to 500 mHz. The separation between the spacecraft was 1,000 km, with atom interferometers 200 m long and shades from sunlight used at each end. A careful analysis of many error sources was included, but requirements on the time-stability of both the laser wavefront aberrations and the atom temperatures in the atom clouds were not investigated. After including these considerations, the laser wavefront aberration stability requirement to meet the quoted sensitivity level is about 1\times10-8 wavelengths, and is far tighter than for LISA. Also, the temperature fluctuations between atom clouds have to be less than 1 pK. An alternate atom interferometer GW mission in Earth orbit called AGIS-LEO with 30 km satellite separation has been suggested recently. The reduction of wavefront aberration noise by sending the laser beam through a high-finesse mode-scrubbing optical cavity is discussed briefly, but the requirements on such a cavity are not given. Unfortunately, such an Earth-orbiting mission seems to be considerably more difficult to design than a non-geocentric mission and does not appear to have comparably attractive scientific goals.Comment: Submitted to Proc. 46th Rencontres de Moriond: Gravitational Waves and Experimental Gravity, March 20 - 27, 2011, La Thuile, Ital

Sneutrino condensate as a candidate for the hot big bang cosmology

If inflationary paradigm is correct, then it must create conditions for the hot big bang model with all observed matter, baryons and the seed perturbations for the structure formation. In this paper we propose a scenario where the inflaton energy density is dumped into the bulk in a brane world setup, and all the required physical conditions are created by the right handed neutrino sector within supersymmetry. The scalar component of the right handed Majorana neutrino is responsible for generating the scale invariant fluctuations in the cosmic microwave background radiation, reheating the Universe at a temperature~$T_{rh}\leq 10^{9}$ GeV, and finally generating the lepton/baryon asymmetry, $n_{B}/s\sim 10^{-10}$, with no lepton/baryon isocurvature fluctuations.Comment: 19 pages, 3 figures. Some discussion on neutrino masses and baryogenesis, and other small changes adde

A New Technique for Detecting Supersymmetric Dark Matter

We estimate the event rate for excitation of atomic transition by photino-like dark matter. For excitations of several eV, this event rate can exceed naive cross-section by many orders of magnitude. Although the event rate for these atomic excitation is smaller than that of nuclear recoil off of non-zero spin nuclei, the photons emitted by the deexcitation are easier to detect than low-energy nuclear recoils. For many elements, there are several low-lying states with comparable excitation rates, thus, spectral ratios could be used to distinguish signal from background.Comment: 6 pages plain te

Single-photon signals at LEP in supersymmetric models with a light gravitino

We study the single-photon signals expected at LEP in models with a very light gravitino. The dominant process is neutralino-gravitino production (e+e- -> chi+ G) with subsequent neutralino decay via chi->gamma+G, giving a gamma+E_miss signal. We first calculate the cross section at arbitrary center-of-mass energies and provide new analytic expressions for the differential cross section valid for general neutralino compositions. We then consider the constraints on the gravitino mass from LEP 1 and LEP161 single-photon searches, and possible such searches at the Tevatron. We show that it is possible to evade the stringent LEP 1 limits and still obtain an observable rate at LEP 2, in particular in the region of parameter space that may explain the CDF e+e+gamma+gamma+E_T,miss event. As diphoton events from neutralino pair-production would not be kinematically accessible in this scenario, the observation of whichever photonic signal will discriminate among the various light-gravitino scenarios in the literature. We also perform a Monte Carlo simulation of the expected energy and angular distributions of the emitted photon, and of the missing invariant mass expected in the events. Finally we specialize the results to the case of a recently proposed one-parameter no-scale supergravity model.Comment: 31 pages, LaTeX, 14 figures (included

Implications of Low Energy Supersymmetry Breaking at the Tevatron

The signatures for low energy supersymmetry breaking at the Tevatron are investigated. It is natural that the lightest standard model superpartner is an electroweak neutralino, which decays to an essentially massless Goldstino and photon, possibly within the detector. In the simplest models of gauge-mediated supersymmetry breaking, the production of right-handed sleptons, neutralinos, and charginos leads to a pair of hard photons accompanied by leptons and/or jets with missing transverse energy. The relatively hard leptons and softer photons of the single e^+e^- \gamma \gamma + \EmissT event observed by CDF implies this event is best interpreted as arising from left-handed slepton pair production. In this case the rates for l^{\pm} \gamma \gamma + \EmissT and \gamma \gamma + \EmissT are comparable to that for l^+l^- \gamma \gamma + \EmissT.Comment: 18 pages, Latex, tables correcte

Predictions for Higgs and SUSY spectra from SO(10) Yukawa Unification with mu > 0

We use $t, b, \tau$ Yukawa unification to constrain SUSY parameter space. We find a narrow region survives for $\mu > 0$ (suggested by \bsgam and the anomalous magnetic moment of the muon) with $A_0 \sim - 1.9 m_{16}$, $m_{10} \sim 1.4 m_{16}$, $m_{16} \sim 1200 -3000$ \gev and $\mu, M_{1/2} \sim 100 - 500$ \gev. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.Comment: 10 pages, 3 figures, revised version to be published in PR