One-loop gg\to b\bar{b} effects in the main irreducible background to exclusive H\to b\bar{b} production at the LHC

We calculate the amplitude of $gg\to b\bar{b}$ production for the colour singlet, J _z =0, di-gluon state at $\mathcal{O}(\alpha_{\mathrm{S}}^{2})$ order. We consider the cancellation and a realistic cut-off, of the infrared divergent terms. We show that the one-loop radiative QCD contributions effectively reduce the Born level result for the central exclusive $b\bar{b}$ cross section at the LHC. This process is essentially the only irreducible QCD background to the exclusive $H\to b\bar{b}$ signal.     

Why is \mathcal{CPT} Fundamental?

Lüders and Pauli proved the theorem based on Lagrangian quantum field theory almost half a century ago. Jost gave a more general proof based on “axiomatic” field theory nearly as long ago. The axiomatic point of view has two advantages over the Lagrangian one. First, the axiomatic point of view makes clear why is fundamental—because it is intimately related to Lorentz invariance. Secondly, the axiomatic proof gives a simple way to calculate the transform of any relativistic field without calculating , and separately and then multiplying them. The purpose of this pedagogical paper is to “deaxiomatize” the theorem by explaining it in a few simple steps. We use theorems of distribution theory and of several complex variables without proof to make the exposition elementary.     

Data on Neutron–Neutron Scattering Length from the Reaction $$\boldsymbol{n+^{2}\textrm{H}\to n+n+p}$$ at $$\boldsymbol{E_{n}=60}$$ MeV

Physics of Atomic Nuclei - The $${}^{1}S_{0}$$ neutron–neutron ( $$nn$$ ) scattering length was measured in the neutron–deuteron ( $$nd$$ ) breakup reaction at an energy of 60 MeV. The...     

Structural, thermal and transport properties of {\text{B}}{{\text{i}}_4}{{\text{V}}_{2 - {\text{x}}}}{\text{G}}{{\text{a}}_{\text{x}}}{{\text{O}}_{11 - \delta }} (0 ≤ x ≤ 0.4)

Solid electrolytes are mostly used in solid oxide fuel cells (SOFC). In the present study, gallium-substituted compounds ( $ {\text{B}}{{\text{i}}_4}{{\text{V}}_{2 - {\text{x}}}}{\text{M}}{{\text{e}}_{\text{x}}}{{\text{O}}_{11 - \delta }} $ ; Me?=?Ga³⁺; 0≤x≤0.4) were prepared by solid-state reaction technique for its use as an electrolyte in SOFC. Structural and conductivity behavior was studied as a function of the Ga³⁺ substitution on vanadium site. The compounds remain in the orthorhombic α-phase for x?=?0 and 0.1 whereas higher concentration of dopant leads to β-phase stabilization. The highest and lowest ionic conductivity were observed in x?=?0.2 and x?=?0.4 samples, respectively. The prepared samples were studied by using alternating current conductivity, differential thermal analysis and X-ray diffraction techniques. The results are discussed on the basis of formation of oxygen vacancy and its ordering.     

Optical properties of $$\hbox {TlGa}(\hbox {S}_{{x}}\hbox {Se}_{1-x})_{2}$$ layered mixed crystals $$(0 \le x \le 1)$$(0≤x≤1): Absorption edge and photoluminescence study at $$T = 10\hbox { K}$$T=10K

Industrial demand for neutrons constrains careful energy measurements. Elastic scattering of monoenergetic \(\alpha \)-particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with specific energy is obtained by counting the number of \(\alpha \)-particles in the corresponding location on the charged particle detector. Monte Carlo simulation and COMSOL Multiphysics5.2 are used to account for one-to-one collision of neutrons with \(\alpha \)-particles.     

The CUORICINO 130Te ββ-decay experiment and a new limit on T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{0\nu } (\beta \beta )

The CUORICINO ββ-decay detector is an array of 62 TeO2 bolometers; 44 are 5×5×5-cm crystals made with natural tellurium (33.8% ¹³⁰Te). There are 18, 3×3×6-cm crystals, 14 of which are made of natural tellurium, 2 are isotopically enriched to 75% in ¹³⁰Te, and 2 are enriched to 82.3% in ¹²⁸Te. The total mass of ¹³⁰Te is ～ 11 kg. The background rate is 0.23 ± 0.04 counts/keV/kg/yr in the energy interval 2480 to 2600 keV. During the cooling process, some of the wires became disconnected and only 32 of the large and 16 of the smaller crystals could be read out. The data presented here come from 29 of the 5×5×5-cm crystals containing 6.2 kg of ¹³⁰Te. The new limit on the half-life is $T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0em} 2}}^{0\nu } \geqslant 5 \times 10^{23} yr$ , corresponding to an effective Majorana mass of the electron neutrino 〈m _ν〉 between 0.42 and 2.05 eV, depending on the nuclear model used to analyze the data.     

$\mathcal {}$-Matrix-valued Wave Packet Frames in L2(ℝd,ℂs×r)$L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})$

We study frame properties of a matrix-valued wave packet system in the matrix-valued function space \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\), where the lower frame condition is controlled by a bounded linear operator \(\mathcal {K}\) on \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\) (lower \(\mathcal {K}\)-frame condition, in short). There are many differences between ordinary frames and \(\mathcal {K}\)-frames. The lower \(\mathcal {K}\)-frame condition for matrix-valued wave packet Bessel sequences in \(L^{2}(\mathbb {R}^{d},\mathbb {C}^{s\times r})\) in terms of operators; a trace functional associated with a bounded linear operator on \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\); and a series associated with a matrix-valued Bessel sequence is presented. It is shown that matrix-valued wave packet frames are stable under small perturbation with respect to wave packet window functions.     

Superconductivity in the doped “pseudo-ladder” compound CaCu$_\mathsf{2}$O$_\mathsf{3}$

An effective anisotropic t-J model for the pseudo-ladder compound CaCu₂O₃ is proposed based on recent experimental studies and band structure calculations. Superconducting pairing mediated by the exchange interaction in the model is investigated as a function of doping away from the antiferromagnetic insulating state. It is shown that strong anisotropy in the electronic spectrum suppresses superconducting temperature in comparison with conventional copper-oxide superconductors with square lattices.     

Cool white light emission on Ca3−(l+n)MgSi2O8:\mathrm{Ce}_{\mathrm{l}}^{3+}, \mathrm{Eu}_{n}^{2+} phosphors and analysis of energy transfer mechanism

Rare earth ions (Ce³⁺, Eu²⁺) activated Ca₃MgSi₂O₈ (CMSO) phosphors have been synthesized using solid-state reaction method in 95%N₂+5%H₂ reduction atmosphere at elevated temperatures by varying Eu²⁺ concentration from 0.0075 to 0.0300 at the fixed Ce_0.03 concentration to study their photoluminescence (PL) properties. An energy transfer occurs from Ce³⁺ to Eu²⁺ through a significant overlap of Eu²⁺ excitation spectrum with Ce³⁺ emission spectrum in CMSO, together with the systematic relative decrease and increase in emission bands of Ce³⁺ and Eu²⁺, respectively, have been observed. To support the phenomenon, diffuse reflectance spectra show various absorption levels corresponding to Ce³⁺, Eu²⁺, and/or mixture of both rare earth ions. An optimum emission was realized at 0.0150 of Eu²⁺ via. energy transfer from Ce³⁺ ion. By utilizing the principle of energy transfer, the critical distance (R _c ) between activator ions was found to be 18.64 Å. The CIE chromaticity coordinates measured on the Ca₃MgSi₂O₈:Ce³⁺, Eu²⁺ phosphors excited under ultraviolet (365 nm) source shows the values lie in cool white light region could be applied to solid state lighting.     

Inclusion relations for the spaces L(ℝ), \mathcal{H}\mathcal{K} (ℝ) ∩ \mathcal{B}\mathcal{V} (ℝ), and L 2(ℝ)

The inclusion relations for the spaces $ \mathcal{H}\mathcal{K} $ (I), L(I), $ \mathcal{H}\mathcal{K} $ (I) ∩ $ \mathcal{B}\mathcal{V} $ (I), and L ²(I) are found. On unbounded intervals, functions in $ \mathcal{H}\mathcal{K} $ (I) ∩ $ \mathcal{B}\mathcal{V} $ (I) need not be Lebesgue integrable.     

Can a non-symmetric metric mimic NCQFT in $e^ + e^- \to \gamma \gamma$?

In the non-symmetric gravitational theory (NGT) the space-time metric departs from the flat-space Minkowski form in such a way that it is no longer symmetric, i.e. . We find that in the most conservative such scenario coupled to quantum field theory, which we call minimally non-symmetric quantum field theory (MNQFT), there are experimentally measurable consequences similar to those from non-commutative quantum field theory (NCQFT). This can be expected from the Seiberg-Witten map which has recently been interpreted as equating gauge theories on non-commutative space-times with those in a field-dependent gravitational background. In particular, in scattering processes such as the pair annihilation , both theories make the same striking prediction that the azimuthal cross section oscillates in . However the predicted number of oscillations differs in the two theories: MNQFT predicts between one and four, whereas NCQFT has no such restriction.Received: 17 May 2004, Revised: 10 September 2004, Published online: 18 November 2004This work was supported by the Department of Physics at Tsinghua University and the Chinese Academy of Sciences.     

Three-Body Baryonic B ̄ 0 → Λ c + p ̄ π 0 $\bar {B}^{0}\rightarrow {{\varLambda }}^{+}_{c} \bar {p} \pi ^{0}$ Decay

International Journal of Theoretical Physics - We study the three-body baryonic decay $ \bar {B}^{0}\rightarrow {{\varLambda }}^{+}_{c} \bar {p} \pi ^{0}$ based on the factorization approach. The...     

$$Q\bar{Q}$$ ($$Q\in \{b,c\}$$Q∈{b,c}) spectroscopy using the Cornell potential

The mass spectra and decay properties of heavy quarkonia are computed in nonrelativistic quark-antiquark Cornell potential model. We have employed the numerical solution of Schrödinger equation to obtain their mass spectra using only four parameters namely quark mass (\(m_c\), \(m_b\)) and confinement strength (\(A_{c\bar{c}}\), \(A_{b\bar{b}}\)). The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are computed perturbatively to determine the mass spectra of excited S, P, D and F states. Digamma, digluon and dilepton decays of these mesons are computed using the model parameters and numerical wave functions. The predicted spectroscopy and decay properties for quarkonia are found to be consistent with available data from experiments, lattice QCD and other theoretical approaches. We also compute mass spectra and life time of the \(B_c\) meson without additional parameters. The computed electromagnetic transition widths of heavy quarkonia and \(B_c\) mesons are in tune with available experimental data and other theoretical approaches.     

Contribution of a heavy singlet quark to the mass differences \Delta m_{K^o } , \Delta m_{B_d } , and \Delta m_{B_s } and to the CP-violation parameter ɛ K

It is shown that, within the Standard Model extended by including a singlet quark heavy enough to prevent its direct detection at LHC, the mass differences $ \Delta m_{B_d } $ and $ \Delta m_{B_s } $ and the parameter of CP violation in K-meson oscillations, ? _K , acquire universal corrections of about 5 to 10%. Implicit experimental constraints on the mass of this new quark are discussed.     

A fresh look at η 2(1645), η 2(1870), η 2(2030) and f 2(1910) in \bar{p}p \to \eta \pi ^{0}\pi ^{0}\pi ^{0}

There is a large discrepancy between results of Crystal Barrel and WA102 for the branching ratio R=BR[η ₂(1870)→a ₂(1320)π]/BR[η ₂(1870)→f ₂(1270)η]. An extensive re-analysis of the Crystal Barrel data redetermines branching ratios for decays of η ₂(1870), η ₂(1645), η ₂(2030) and f ₂(1910). This re-analysis confirms a small value for R of 1.60±0.39, inconsistent with the value 20.4±6.6 of WA102. The likely origin of the discrepancy is that the WA102 data contain a strong f ₂(1910)→a ₂ π signal as well as η ₂(1870). There is strong evidence that the η ₂(1870) has resonant phase variation. A peak in f ₂(1270)a ₀(980) confirms closely the parameters of the a ₂(2255) resonance observed previously. A peak in η ₂(2030)π is interpreted naturally in terms of π ₂(2245) with reduced errors for mass and width M=2285±20(stat)±25(syst) MeV, Γ=250±20(stat)±25(syst) MeV.     

Exact calculation of O(α) QED corrections for f_1 \overline {f_1 } \uparrow f_2 \overline {f_2 } processes induced by polarized incident particles

For $f_1 \overline {f_1 } \uparrow f_2 \overline {f_2 }$ (γ) processes induced by polarized incident particles, exact covariant expressions for the energy spectrum of one of the emitted fermions, for the total cross section, and for the polarization asymmetry are obtained in theα³ order of QED.     

Finite Size XXZ Spin Chain with Anisotropy Parameter Δ= \frac{1} {2}

We find an analytic solution of the Bethe–Ansatz equations (BAE) for the special case of a finite XXZ spin chain with free boundary conditions and with a complex surface field which provides for U_q(sl(2)) symmetry of the Hamiltonian. More precisely, we find one nontrivial solution, corresponding to the ground state of the system with anisotropy parameter Δ= $\frac{1}{2}$ corresponding to q³=?1. With a view to establishing an exact representation of the ground state of the finite size XXZ spin chain in terms of elementary functions, we concentrate on the crossing parameter η dependence around η=π/3 for which there is a known solution. The approach taken involves the use of a physical solution Q of Baxter's T-Q equation, corresponding to the ground state, as well as a non-physical solution P of the same equation. The calculation of P and then of the ground state derivative is covered. Possible applications of this derivative to the theory of percolation have yet to be investigated. As far as the finite XXZ spin chain with periodic boundary conditions is concerned, we find a similar solution for an assymetric case which corresponds to the 6-vertex model with a special magnetic field. For this case we find the analytic value of the “magnetic moment” of the system in the corresponding state.     

Bäcklund transformations for the equationz_{uv} = 2z_u z_v /z + \bar z

The equation for the complex variablez is equivalent to the field equation for a SO(2, 1)-invariant nonlinear -model in two dimensions. A connection on a SU(2) bundle is given, such that the requirement of the vanishing curvature of the connection implies that equation. Bäcklund transformations, considered as gauge transformations of the connection, are explicity obtained.     

Hidden local symmetry and the reaction e+e- → \pi^{+}_{} \pi^{-}_{} \pi^{+}_{} \pi^{-}_{} at energies \sqrt{{s}} ⩽ 1 GeV

Based on the generalized hidden local symmetry as the chiral model of pseudoscalar, vector, and axial vector mesons, the excitation curve of the reaction e ⁺ e ^- → $ \pi^{+}_{}$ $ \pi^{-}_{}$ $ \pi^{+}_{}$ $ \pi^{-}_{}$ is calculated for energies in the interval 0.65 ? $ \sqrt{{s}}$ ? 1 GeV. The theoretical predictions are compared to available data of CMD-2 and BaBaR. It is shown that the inclusion of heavy isovector resonances ρ(1450) and ρ(1700) is necessary for reconciling calculations with the data. It is found that at $ \sqrt{{s}}$ ≈ 1 GeV the contributions of the above resonances are much larger, by a factor of 30, than the ρ(770) one, and amount to a considerable fraction ～ 0.3-0.6 of the latter at $ \sqrt{{s}}$ ～ m _ρ .