On Lagrangian approach to self-dual gauge fields in spacetime of nontrivial topology

We study the Lagrangian description of chiral bosons, p-form gauge fields with (anti–)self-dual gauge field strengths, in D = 2 p + 2 dimensional spacetime of non-trivial topology. We show that the manifestly Lorentz and diffeomorphism invariant Pasti-Sorokin-Tonin (PST) approach is consistent and produces the (anti-)self-duality equation also in topologically nontrivial spacetime. We discuss in what circumstances the nontrivial topology makes difference between two disconnected, da-timelike and da-spacelike branches of the PST system, the gauge fixed version of which are described by not manifestly invariant Henneaux-Teitelboim (HT) and Perry-Schwarz (PS) actions, respectively

Mixing stops at the LHC

We study the phenomenology of a light stop NLSP in the presence of large mixing with either the first or the second generation. R-symmetric models provide a prime setting for this scenario, but our discussion also applies to the MSSM when a significant amount of mixing can be accommodated. In our framework the dominant stop decay is through the flavor violating mode into a light jet and the LSP in an extended region of parameter space. There are currently no limits from ATLAS and CMS in this region. We emulate shape-based hadronic SUSY searches for this topology, and find that they have potential sensitivity. If the extension of these analyses to this region is robust, we find that these searches can set strong exclusion limits on light stops. If not, then the flavor violating decay mode is challenging and may represent a blind spot in stop searches even at 13 TeV. Thus, an experimental investigation of this scenario is well motivated

In-Pile 4He Source for UCN Production at the ESS

ESS will be a premier neutron source facility. Unprecedented neutron beam intensities are ensured by spallation reactions of a 5 MW, 2.0 GeV proton beam impinging on a tungsten target equipped with advanced moderators. The work presented here aims at investigating possibilities for installing an ultra cold neutron (UCN) source at the ESS. One consequence of using the recently proposed flat moderators is that they take up less space than the moderators originally foreseen and thus leave more freedom to design a UCN source, close to the spallation hotspot. One of the options studied is to place a large 4He UCN source in a through-going tube which penetrates the shielding below the target. First calculations of neutron flux available for UCN production are given, along with heat-load estimates. It is estimated that the flux can give rise to a UCN production at a rate of up to <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mn mathvariant="normal">1.5</mn><mo>·</mo><msup><mrow><mn mathvariant="normal">10</mn></mrow><mrow><mn mathvariant="normal">8</mn></mrow></msup></math>  UCN/s. A production in this range potentially allows for a number of UCN experiments to be carried out at unprecedented precision, including, for example, quantum gravitational spectroscopy with UCNs which rely on high phase-space density

Constraints on Heavy Neutrino and SUSY Parameters Derived from the Study of Neutrinoless Double Beta Decay

New constraints on the lepton number violating (LNV) parameters are derived from the analysis of the neutrinoless double beta ( <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mn mathvariant="normal">0</mn><mi>ν</mi><mi>β</mi><mi>β</mi></math> ) decay in the hypothesis that this process would occur through the exchange of heavy neutrinos and/or SUSY particles. For derivation, we use new values of both phase space factors (PSFs) and nuclear matrix elements (NMEs) calculated with numerical codes developed recently, as well as the most recent experimental lifetimes. The NMEs are computed with a shell model (ShM) code for <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi mathvariant="normal"> </mi></mrow><mrow><mn>48</mn></mrow></msup><mtext>C</mtext><mtext>a</mtext></math> , <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi mathvariant="normal"> </mi></mrow><mrow><mn>76</mn></mrow></msup><mtext>G</mtext><mtext>e</mtext></math> , and <math id="M4" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi mathvariant="normal"> </mi></mrow><mrow><mn>82</mn></mrow></msup><mtext>S</mtext><mtext>e</mtext></math> nuclei, while at present similar ShM results are available only for the first nucleus. We compare our results with similar ones from literature, obtained with ShM, QRPA, and IBM-2 methods, and conclude that more results are needed for a relevant analysis on the validity of NMEs associated with these decay mechanisms

Analog geometry in an expanding fluid from AdS/CFT perspective

The dynamics of an expanding hadron fluid at temperatures below the chiral transition is studied in the framework of AdS/CFT correspondence. We establish a correspondence between the asymptotic AdS geometry in the 4+1 dimensional bulk with the analog spacetime geometry on its 3+1 dimensional boundary with the background fluid undergoing a spherical Bjorken type expansion. The analog metric tensor on the boundary depends locally on the soft pion dispersion relation and the four-velocity of the fluid. The AdS/CFT correspondence provides a relation between the pion velocity and the critical temperature of the chiral phase transition

The massive fermion phase for the U(N) Chern-Simons gauge theory in D=3 at large N

We explore the phase structure of fermions in the U(N) Chern-Simons Gauge theory in three dimensions using the large N limit where N is the number of colors and the fermions are taken to be in the fundamental representation of the U(N) gauge group. In the large N limit, the theory retains its classical conformal behavior and considerable attention has been paid to possible AdS/CFT dualities of the theory in the conformal phase. In this paper we present a solution for the massive phase of the fermion theory that is exact to the leading order of ‘t Hooft’s large N expansion. We present evidence for the spontaneous breaking of the exact scale symmetry and analyze the properties of the dilaton that appears as the Goldstone boson of scale symmetry breaking

The Study of Thermal Conditions on Weibel Instability

Weibel electromagnetic instability has been studied analytically in relativistic plasma with high parallel temperature, where <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">|</mo><mi>α</mi><mo>=</mo><mo stretchy="false">(</mo><mrow><mrow><mi>m</mi><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow><mo>/</mo><mrow><msub><mrow><mi>T</mi></mrow><mrow><mo stretchy="false">∥</mo></mrow></msub></mrow></mrow><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mn>1</mn><mo>+</mo><mrow><mrow><msup><mrow><msub><mrow><mover accent="true"><mrow><mi>p</mi></mrow><mo>^</mo></mover></mrow><mrow><mo>⊥</mo></mrow></msub></mrow><mrow><mn>2</mn></mrow></msup></mrow><mo>/</mo><mrow><msup><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mrow><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mrow><mrow><mn>1</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></mrow></msup><mo stretchy="false">|</mo><mo>≪</mo><mn>1</mn></math> and while the collision effects of electron-ion scattering have also been considered. According to these conditions, an analytical expression is derived for the growth rate of the Weibel instability for a limiting case of <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">|</mo><mi>ζ</mi><mo>=</mo><msqrt><mrow><mrow><mi>α</mi></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></msqrt><mo stretchy="false">(</mo><mrow><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>′</mi></mrow></msup></mrow><mo>/</mo><mrow><mi>c</mi><mi>k</mi></mrow></mrow><mo stretchy="false">)</mo><mo stretchy="false">|</mo><mo>≪</mo><mn>1</mn></math> , where <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mi>′</mi></mrow></msup></mrow></math> is the sum of the wave frequency of instability and the collision frequency of electrons with background ions. The results show that in the limiting condition <math id="M4" xmlns="http://www.w3.org/1998/Math/MathML"><mi>α</mi><mo>≪</mo><mn>1</mn></math> there is an unusual situation of the Weibel instability so that <math id="M5" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>T</mi></mrow><mrow><mo stretchy="false">∥</mo></mrow></msub><mo>≫</mo><msub><mrow><mi>T</mi></mrow><mrow><mo>⊥</mo></mrow></msub></math> , while in the classic Weibel instability <math id="M6" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>T</mi></mrow><mrow><mo stretchy="false">∥</mo></mrow></msub><mo>≪</mo><msub><mrow><mi>T</mi></mrow><mrow><mo>⊥</mo></mrow></msub></math> . The obtained results show that the growth rate of the Weibel instability will be decreased due to an increase in the number of collisions and a decrease in the anisotropic temperature by the increasing of plasma density, while the increase of the parameter <math id="M7" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mover accent="true"><mrow><mi>γ</mi></mrow><mo>^</mo></mover></mrow><mrow><mo>⊥</mo></mrow></msub><mo>=</mo><mo stretchy="false">(</mo><mn>1</mn><mo>+</mo><mrow><mrow><msup><mrow><msub><mrow><mover accent="true"><mrow><mi>p</mi></mrow><mo>^</mo></mover></mrow><mrow><mo>⊥</mo></mrow></msub></mrow><mrow><mn>2</mn></mrow></msup></mrow><mo>/</mo><mrow><msup><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mrow><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mrow><mrow><mn>1</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></mrow></msup></math> leads to the increase of the Weibel instability growth rate

A convenient implementation of the overlap between arbitrary Hartree–Fock–Bogoliubov vacua for projection

Overlap between Hartree–Fock–Bogoliubov (HFB) vacua is very important in the beyond mean-field calculations. However, in the HFB transformation, the <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>U</mi><mo>,</mo><mi>V</mi></math> matrices are sometimes singular due to the exact emptiness ( <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>=</mo><mn>0</mn></math> ) or full occupation ( <math altimg="si3.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>u</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>=</mo><mn>0</mn></math> ) of some single-particle orbits. This singularity may cause some problem in evaluating the overlap between HFB vacua through Pfaffian. We found that this problem can be well avoided by setting those zero occupation numbers <math altimg="si4.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>u</mi></mrow><mrow><mi>i</mi></mrow></msub></math> , <math altimg="si5.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math> to some tiny values denoted by <math altimg="si6.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>ε</mi><mspace width="0.2em"/><mo stretchy="false">(</mo><mo>&gt;</mo><mn>0</mn><mo stretchy="false">)</mo></math> , which numerically satisfies <math altimg="si7.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>1</mn><mo>+</mo><msup><mrow><mi>ε</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>=</mo><mn>1</mn></math> (e.g., <math altimg="si8.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>ε</mi><mo>=</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>8</mn></mrow></msup></math> when using the double precision data type). This treatment does not change the HFB vacuum state because <math altimg="si9.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>u</mi></mrow><mrow><mi>i</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>,</mo><msubsup><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>=</mo><msup><mrow><mi>ε</mi></mrow><mrow><mn>2</mn></mrow></msup></math> are numerically zero relative to 1. Therefore, for arbitrary HFB transformation, we say that the U , V matrices can always be nonsingular. From this standpoint, we present a new convenient Pfaffian formula for the overlap between arbitrary HFB vacua, which is especially suitable for symmetry restoration. Testing calculations have been performed for this new formula. It turns out that our method is reliable and accurate in evaluating the overlap between arbitrary HFB vacua

T-duality as coordinates permutation in double space for weakly curved background

In the paper [1] we showed that in double space, where all initial coordinates x μ are doubled x μ → y μ , the T-duality transformations can be performed by exchanging places of some coordinates x a and corresponding dual coordinates y a . Here we generalize this result to the case of weakly curved background where in addition to the extended coordinate we will also transform extended argument of background fields with the same operator T ^ a $${\widehat{\mathcal{T}}}^a$$ . So, in the weakly curved background T-duality leads to the physically equivalent theory and complete set of T-duality transformations form the same group as in the flat background. Therefore, the double space represent all T-dual theories in unified manner

The Effect of Nuclear Elastic Scattering on Temperature Equilibration Rate of Ions in Fusion Plasma

A plasma with two different particle types and at different temperatures has been considered, so that each type of ion with Maxwell-Boltzmann distribution function is in temperature equilibrium with itself. Using the extracted nuclear elastic scattering differential cross-section from experimental data, solving the Boltzmann equation, and also taking into account the mobility of the background particles, temperature equilibration rate between two different ions in a fusion plasma is calculated. The results show that, at higher temperature differences, effect of nuclear elastic scattering is more important in calculating the temperature equilibration rate. The obtained expressions have general form so that they are applicable to each type of particle for background ( <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>b</mi></mrow></math> ) and each type for projectile ( <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi></mrow></math> ). In this paper, for example, an equimolar Deuterium-Hydrogen plasma with density <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><mi>n</mi><mo>=</mo><mn>5</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>25</mn></mrow></msup></math>  cm−3 is chosen in which the deuteron is the background particle with temperature (also electron temperature) <math id="M4" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>=</mo><mn>1</mn></math>  keV (usual conditions for a fusion plasma at the ignition instant) and the proton is the projectile with temperature <math id="M5" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>T</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>&gt;</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub></math> . These calculations, particularly, are very important for ion fast ignition in inertial confinement fusion concept