122034006
Neutrino deuteron scattering in effective field theory
119519405
Parity Violation in Polarized-Gamma Proton Compton Scattering
Polarized beam gamma p Compton scattering provides a theoretically clean way to extract the isovector parity violating pion-nucleon coupling constant $h_{\pi NN}^{(1)}$. This channel is more tractable experimentally than the recently proposed extraction of $h_{\pi NN}^{(1)}$ from the Bedaque-Savage process --- polarized target gamma p compton scattering. The leading parity violating effect is calculated using Heavy Baryon Chiral Perturbation Theory. The size of the asymmetry is estimated to be ~ 4 10^{-8} for 120 MeV photon energy.
119418730
Large-Nc quark distributions in the delta and chiral logarithms in quark distributions of the nucleon
Abstract In a world with two quark flavors and a large number of colors ( N c ), the polarized and unpolarized quark distributions in the delta are completely determined by those in the nucleon up to relative O (1/N c 2 ) . In particular, we find q Δ (x)=[(1±2T z )u N (x)+(1∓2T z )d N (x)]/2(1+ O (1/N c 2 )) and Δq Δ (x)=[(5±2T z )Δu N (x)+(5∓2T z )Δd N (x)]/10(1+ O (1/N c 2 )) , where q = u , d and T z the charge state of a delta. The result can be used to estimate the leading chiral-logarithmic corrections to the quark distributions in the nucleon.
13534760
Constructing parton convolution in effective field theory.
Parton convolution models have been used extensively in describing the sea quarks in the nucleon and explaining quark distributions in nuclei (the EMC effect). From the effective field theory point of view, we construct the parton convolution formalism which has been the underlying conception of all convolution models. We explain the significance of scheme and scale dependence of the auxiliary quantities such as the pion distributions in a nucleon. As an application, we calculate the complete leading nonanalytic chiral contribution to the isovector component of the nucleon sea.
119491739
Twisted valence quarks and hadron interactions on the lattice
Abstract We consider QCD with valence and sea quarks obeying different boundary conditions. We point out that the energy of low lying two hadron states do not depend on the boundary condition of the sea quarks (up to exponentially small corrections). Thus, the advantages in using twisted boundary conditions on the lattice QCD extraction of nucleon–nucleon phase shifts can be gained without the need of new gauge configurations, even in fully unquenched calculations.
119272530
Model analysis of thermal UV-cutoff effects on the chiral critical surface at finite temperature and chemical potential
We study the effects of temporal UV-cutoff on the chiral critical surface in hot and dense QCD using a chiral effective model. Recent lattice QCD simulations indicate that the curvature of the critical surface might change toward the direction in which the first-order phase transition becomes stronger on increasing the number of lattice sites. To investigate this effect on the critical surface in an effective model approach, we use the Nambu-Jona-Lasinio model with finite Matsubara frequency summation. We find that the nature of the curvature of the critical surface does not alter appreciably as we decrease the summation number, which is unlike the case that was observed in recent lattice QCD studies. This may suggest that the dependence of chemical potential on the coupling strength or some additional interacting terms such as vector interactions could play an important role at finite density.
119285071
Dark matter coupling to electroweak gauge and Higgs bosons: An effective field theory approach
Abstract If dark matter is a new species of particle produced in the early universe as a cold thermal relic (a weakly-interacting massive particle—WIMP), its present abundance, its scattering with matter in direct-detection experiments, its present-day annihilation signature in indirect-detection experiments, and its production and detection at colliders, depend crucially on the WIMP coupling to standard-model (SM) particles. It is usually assumed that the WIMP couples to the SM sector through its interactions with quarks and leptons. In this paper we explore the possibility that the WIMP coupling to the SM sector is via electroweak gauge and Higgs bosons. In the absence of an ultraviolet-complete particle-physics model, we employ effective field theory to describe the WIMP–SM coupling. We consider both scalars and Dirac fermions as possible dark-matter candidates. Starting with an exhaustive list of operators up to dimension 8, we present detailed calculation of dark-matter annihilations to all possible final states, including γγ, γ Z , γ h , ZZ , Zh , W + W − , hh , and f f ¯ , and demonstrate the correlations among them. We compute the mass scale of the effective field theory necessary to obtain the correct dark-matter mass density, and well as the resulting photon line signals.
119179797
Searching for high speed long-lived charged massive particles at the LHC
The conventional way to search for long-lived CHArged Massive Particles (CHAMPs) is to identify slow (small β) tracks using delayed time of flight and high ionization energy loss. But at the 7–14 TeV center of mass energy of the LHC, a CHAMP may be highly boosted (high β) and therefore look more like a minimum ionizing particle, while for high momentum muons (≳500 GeV/c) the radiative effect dominates energy deposition. This suggests a new strategy to search for CHAMPs at the LHC. Using energy deposition from different detector components, we construct a boosted decision tree discriminant to separate high momentum CHAMPs from high momentum muons. This method increases substantially the CHAMP discovery potential and it can be used to distinguish possible di-CHAMP or CHAMP–muon resonance models from di-muon resonance models. We illustrate the new method using a mGMSB model and a recently proposed di-CHAMP model and we give updated CHAMP mass limits for these two models using the results from a recent CDF CHAMP search.
122544309
THE MULTI-VALUE OF EFFECTIVE NUCLEON MASS IN HOT/DENSE NUCLEAR MATTER AND THE PHASE TRANSITION
From the Lagrangian of QHD-I model, we investigate the effective nucleon mass under the mean field approximation in a wide temperature region. The multi-solution of self-consistent equation for the effective mass in found. In the high temperature region, the relation between the multi-solutions and the phase transition is analyzed. Furthermore, the variation of energy density in this region is studied.
56112288
Residue theorem and summing over Kaluza-Klein excitations
Applying the equations of motion together with corresponding boundary conditions of bulk profiles at infrared and ultraviolet branes, we verify some lemmas on the eigenvalues of Kaluza-Klein modes in extension of the standard model with a warped extra dimension and the custodial symmetry SU(3){sub c}xSU(2){sub L}xSU(2){sub R}xU(1){sub X}xP{sub LR}. Using the lemmas and performing properly analytic extensions of bulk profiles, we present the sufficient condition for a convergent series of Kaluza-Klein excitations and sum over the series through the residue theorem. The method can also be applied to sum over the infinite series of Kaluza-Klein excitations in a universal extra dimension. Furthermore, we analyze the possible connection between the propagators in five-dimensional full theory and the product of bulk profiles with corresponding propagators of exciting Kaluza-Klein modes in four-dimensional effective theory, and recover some relations presented in the literature for warped and universal extra dimensions, respectively. As an example, we present the correction from new physics to the branching ratio of B{yields}X{sub s{gamma}} to the order O({mu}{sub EW}{sup 2}/{Lambda}{sub KK}{sup 2}) in extension of the standard model with a warped extra dimension and the custodial symmetry, where {Lambda}{sub KK} denotes the energy scale of low-lying Kaluza-Klein excitations and {mu}{sub EW}more » denotes the electroweak energy scale.« less
118573990
Three-dimensional correlated-fermion phase separation from analysis of the geometric mean of the individual susceptibilities
A quasi-Gaussian approximation scheme is formulated to study the strongly correlated imbalanced Fermions thermodynamics, where the mean-field theory is not applicable. The non-Gaussian correlation effects are understood to be captured by the statistical geometric mean of the individual susceptibilities. In the three-dimensional unitary fermions ground state, a universal nonlinear scaling transformation relates the physical chemical potentials with the individual Fermi kinetic energies. For the partial polarization phase separation to full polarization, the calculated critical polarization ratio is δC = [1−(1−ξ)6/5]/[1+(1−ξ)6/5] ≐ 0.34. ξ = 4/9 gives the ratio of the symmetric ground state energy density to that of the ideal fermion gas.