Thermality and heat content of horizons from infinitesimal coordinate transformationsMajhi, Bibhas Ranjan;Padmanabhan, T.
doi: 10.1140/epjc/s10052-013-2651-zpmid: N/A
Abstract Thermal properties of a static horizon (like the entropy S, heat content TS, etc.) can be obtained either from the surface term of the Einstein–Hilbert action or by evaluating the Noether charge, corresponding to the diffeomorphisms generated by the timelike Killing vector field. We show that, for a wide class of geometries, the same results can be obtained using the vector field which produces an infinitesimal coordinate transformation between two physically relevant reference frames, viz. the freely falling frame near the horizon and the static, accelerated, frame. In particular, the infinitesimal coordinate transformation from inertial coordinates to a uniformly accelerated frame can be used to obtain the heat content and entropy of the Rindler horizon. This result offers insight into the observer-dependent degrees of freedom which contribute to the entropy of null surfaces.
Exclusive MSSM Higgs production at the LHC after run ITasevsky, M.
doi: 10.1140/epjc/s10052-013-2672-7pmid: N/A
Abstract We investigate the prospects for Central Exclusive Production (CEP) of MSSM Higgs bosons at the LHC using forward proton detectors proposed to be installed at 220 m and 420 m distance around ATLAS and / or CMS. We summarize the situation after the first and very successful data taking period of the LHC. The discovery of a Higgs boson and results from searches for additional MSSM Higgs bosons from both the ATLAS and CMS experiments, based on data samples each corresponding to about 25 fb−1, have recently led to a proposal of new low-energy MSSM benchmark scenarios. The CEP signal cross section for the process \(H/h \to b \bar{b}\) and its backgrounds are estimated in these new scenarios. We also make some comments about the experimental procedure if the proposed forward proton detectors are to be used to measure the CEP signal.
Counting photons in static electric and magnetic fieldsMück, Wolfgang
doi: 10.1140/epjc/s10052-013-2679-0pmid: N/A
Abstract We describe the electromagnetic field by the massless limit of a massive vector field in the presence of a Coulomb gauge fixing term. The gauge fixing term ensures that, in the massless limit, the longitudinal mode is removed from the spectrum and only the two transverse modes survive. The system, coupled to a classical conserved current, is quantized in the canonical formalism. The classical field configurations due to time-independent electric charges and currents are represented by coherent states of longitudinal and transverse photons, respectively. The occupation number in these states is finite. In particular, the number of longitudinal photons bound by an electric charge q is given by N=q 2/(16πħ).
Generalized states in SFTBonora, L.;Giaccari, S.
doi: 10.1140/epjc/s10052-013-2644-ypmid: N/A
Abstract The search for analytic solutions in open string fields theory à la Witten often meets with singular expressions, which need an adequate mathematical formalism to be interpreted. In this paper we discuss this problem and propose a way to resolve the related ambiguities. Our claim is that a correct interpretation requires a formalism similar to distribution theory in functional analysis. To this end we concretely construct a locally convex space of test string states together with the dual space of functionals. We show that the above suspicious expressions can be identified with well defined elements of the dual.
ΛCDM model with a scalar perturbation vs. preferred direction of the universeLi, Xin;Lin, Hai-Nan;Wang, Sai;Chang, Zhe
doi: 10.1140/epjc/s10052-013-2653-xpmid: N/A
Abstract We present a scalar perturbation for the ΛCDM model, which breaks the isotropic symmetry of the universe. Based on the Union2 data, the least-χ 2 fit of the scalar perturbed ΛCDM model shows that the universe has a preferred direction (l,b)=(287∘±25∘,11∘±22∘). The magnitude of scalar perturbation is about −2.3×10−5. The scalar perturbation for the ΛCDM model implies a peculiar velocity, which is perpendicular to the radial direction. We show that the maximum peculiar velocities at redshift z=0.15 and z=0.015 equal to 73±28 km s−1 and 1099±427 km s−1, respectively. They are compatible with the constraints on the peculiar velocity given by the Planck Collaboration.
Generalized (2+1) dimensional black hole by Noether symmetryDarabi, F.;Atazadeh, K.;Rezaei-Aghdam, A.
doi: 10.1140/epjc/s10052-013-2657-6pmid: N/A
Abstract We use the Noether symmetry approach to find f(R) theory of (2+1) dimensional gravity and (2+1) dimensional black hole solution consistent with this f(R) gravity and the associated symmetry. We obtain f(R)=D 1 R(n/n+1)(R/K)1/n+D 2 R+D 3, where the constant term D 3 plays no dynamical role. Then, we find general spherically symmetric solution for this f(R) gravity which is potentially capable of being as a black hole. Moreover, in the special case D 1=0,D 2=1, namely f(R)=R+D 3, we obtain a generalized BTZ black hole which, other than common conserved charges m and J, contains a new conserved charge Q. It is shown that this conserved charge corresponds to the freedom in the choice of the constant term D 3 and represents symmetry of the action under the transformation R→R′=R+D 3 along the killing vector ∂ R . The ordinary BTZ black hole is obtained as the special case where D 3 is fixed to be proportional to the infinitesimal cosmological constant and consequently the symmetry is broken via Q=0. We study the thermodynamics of the generalized BTZ black hole and show that its entropy can be described by the Cardy–Verlinde formula.
Standard model and new physics contributions to K L and K S into four leptonsD’Ambrosio, Giancarlo;Greynat, David;Vulvert, Grégory
doi: 10.1140/epjc/s10052-013-2678-1pmid: N/A
Abstract We study the K L and K S decays into four leptons (\(e\bar{e}e\bar{e}\), \(\mu\bar{\mu}\mu\bar{\mu}\), \(e\bar{e}\mu\bar{\mu}\)) where we use a form factor motivated by vector meson dominance, and show the dependence of the branching ratios and spectra from the slopes. A precise determination of short-distance contribution to K L →μμ is affected by our ignorance on the sign of the amplitude \(\mathcal{A}(K_{L}\to\gamma\gamma)\) but we show a possibility to measure the sign of this amplitude by studying K L and K S decays in four leptons. We also investigate the effect of New Physics contributions for these decays.
New physics in B → K ∗ μμ ?Altmannshofer, Wolfgang;Straub, David M.
doi: 10.1140/epjc/s10052-013-2646-9pmid: N/A
Abstract Recent experimental results on angular observables in the rare decay B→K ∗ μ + μ − show significant deviations from Standard Model predictions. We investigate the possibility that these deviations are due to new physics. Combining all relevant data on b→s rare decays, we show that a consistent explanation of most anomalies can be obtained by new physics contributing simultaneously to the semi-leptonic vector operator O 9 and its chirality-flipped counterpart \(O_{9}'\). A partial explanation is possible with new physics in O 9 or in dipole operators only. We study in detail the implications for models of new physics, in particular the minimal supersymmetric standard model, models with partial compositeness and generic models with flavour-changing Z′ bosons. In all considered models, contributions to B→K ∗ μ + μ − of the preferred size imply a spectrum close to the TeV scale. We stress that measurements of CP asymmetries in B→K ∗ μ + μ − could provide valuable information to narrow down possible new physics explanations.