HEP Phenomenology·hep-ph

Mon·Aug 8, 2016Monday·August 8, 2016

18 papers—13 primary·5 cross-listed·reconstructed*

01*
Application of the Non-extensive Statistical Approach to High Energy Particle Collisions
Gábor Bíró🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Tamás Sándor Biró🇭🇺 · Károly Ürmössy🇭🇺
In high-energy collisions the number of the created particles is far less than the thermodynamic limit, especially in small colliding systems (e.g. proton-proton). Therefore final-state effects and fluctuations in the one-particle energy distribution are appreciable. As a consequence the characterization of identified hadron spectra with the Boltzmann\,--\,Gibbs thermodynamical approach is insufficient. Instead particle spectra measured in high-energy collisions can be described very well with Tsallis\,--\,Pareto distributions, derived from non-extensive thermodynamics. Using the Tsallis q-entropy formula, a generalization of the Boltzmann\,--\,Gibbs entropy, we interpret the microscopical physics by analysing the Tsallis $q$ and $T$ parameters. In this paper we give a quick overview on these parameters, analyzing identified hadron spectra from recent years in a wide center of mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on this energy and on the particle species. Our findings are described well by a QCD inspired evolution ansatz.
hep-phAIP Conf.Proc.(2017)·15 citations
02*
Muon-Electron Conversion in a Family Gauge Boson Model
Yoshio Koide🇯🇵 · Masato Yamanaka🇯🇵
We study the $μ$ - $e$ conversion in muonic atoms via an exchange of family gauge boson (FGB) $A_{2}^{1}$ in a $U (3)$ FGB model. Within the class of FGB model, we consider three types of family-number assignments for quarks. We evaluate the $μ$ - $e$ conversion rate for various target nuclei, and find that next generation $μ$ - $e$ conversion search experiments can cover entire energy scale of the model for all of types of the quark family-number assignments. We show that the conversion rate in the model is so sensitive to up- and down-quark mixing matrices, $U^{u}$ and $U^{d}$ , where the CKM matrix is given by $V_{CKM} = U^{u †} U^{d}$ . Precise measurements of conversion rates for various target nuclei can identify not only the types of quark family-number assignments, but also each quark mixing matrix individually.
hep-phPLB(2016)·4 citations
03*
CP violating scalar Dark Matter
A. Cordero-Cid🇲🇽 · J. Hernández-Sánchez🇲🇽 · V. Keus🇫🇮 · S. F. King🇬🇧 · S. Moretti🇬🇧 · D. Rojas🇲🇽 · D. Sokołowska🇵🇱
We study an extension of the Standard Model (SM) in which two copies of the SM scalar $S U (2)$ doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are \textit{inert}, are added to the scalar sector. We allow for CP-violation in the \textit{inert} sector, where the lightest \textit{inert} state is protected from decaying to SM particles through the conservation of a $Z_{2}$ symmetry. The lightest neutral particle from the \textit{inert} sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.
hep-phJHEP(2016)·57 citations
04*
Unification and New Particles at the LHC
Nima Arkani-Hamed🇺🇸 · Raffaele Tito D'Agnolo🇺🇸 · Matthew Low🇺🇸 · David Pinner🇺🇸
Precision gauge coupling unification is one of the primary quantitative successes of low energy or split supersymmetry. Preserving this success puts severe restrictions on possible matter and gauge sectors that might appear at collider-accessible energies. In this work we enumerate new gauge sectors which are compatible with unification, consisting of horizontal gauge groups acting on vector-like matter charged under the Standard Model. Interestingly, almost all of these theories are in the supersymmetric conformal window at high energies and confine quickly after the superpartners are decoupled. For a range of scalar masses compatible with both moderately tuned and minimally split supersymmetry, the confining dynamics happen at the multi-TeV scale, leading to a spectrum of multiple spin-0 and spin-1 resonances accessible to the LHC, with unusual quantum numbers and striking decay patterns.
hep-phhep-exJHEP(2016)·17 citations
05*
Probing light-quark Yukawa couplings via hadronic event shapes at lepton colliders
Jun Gao🇺🇸
We propose a novel idea for probing the Higgs boson couplings through the measurement of hadronic event shape distributions in the decay of the Higgs boson at lepton colliders. The method provides a unique test of the Higgs boson couplings and of QCD effects in the decay of the Higgs boson. It can be used to probe the Yukawa couplings of the light quarks and to further test the mechanism of electroweak symmetry breaking. From a case study for the proposed Circular Electron-Positron Collider, assuming a hypothesis of SM-like theory, light-quark couplings with a strength greater than 9% of the bottom-quark Yukawa coupling in the standard model can be excluded.
hep-phhep-exJHEP(2018)·45 citations
06*
Reheating mechanism of Curvaton with Nonminimal Derivative Coupling to Gravity
Taotao Qiu🇨🇳 · Kaixi Feng🇨🇳
In this paper, we continue our study on the curvaton model with nonminimal derivative coupling (NDC) to Einstein gravity proposed in our previous work, focusing on the reheating mechanism. We found that according to whether the curvaton has dominated the background after the end of inflation, it will have two different behaviors of evolution, which should be the general property of curvaton with nonminimal couplings. This will cause diffferent rates of particle creation, which goes on via the parametric resonance process. The reheating temperature is estimated for both cases in which reheating completes before and after curvaton domination, and the constraints are quite loose compared to that of overproduction of gravitino. Finally we investigated the evolution of curvature perturbation during reheating. We have shown both analytically and numerically that the curvature perturbation will not blow up during the resonance process.
hep-phastro-ph.COgr-qchep-thEPJC(2017)·11 citations
07*
Applications of the loop-tree duality
German Rodrigo🇪🇸 · Felix Driencourt-Mangin🇪🇸 · German F. R. Sborlini🇪🇸 · Roger Jose Hernandez-Pinto🇲🇽
We describe a new method to perform NLO calculations, combining real and virtual amplitudes at the integrand level, with a fully local compensation between them in the IR, and between the virtual integrand and properly defined counter-terms in the UV, in such a way that physical observables can be computed in 4 dimensions. One of the advantages of the method is that all the scattering amplitudes are integrated simultaneously, without the need for tensor reduction, or projection onto sets of master integrals. As such, it could offer great progress in the automation of NLO calculations, where the actual bottle-necks are the complexity of the analytical calculations for multi-leg processes, and the numerical stability of the result.
hep-phPoS(2016)·10 citations
08*
FORM, Diagrams and Topologies
Franz Herzog🇳🇱 · Ben Ruijl🇳🇱 · Takahiro Ueda🇳🇱 · J.A.M. Vermaseren (NIKHEF, Amsterdam)🇳🇱 · Andreas Vogt (Liverpool U., Dept. Math.)🇬🇧
We discuss a number of FORM features that are essential in the automatic processing of very large numbers of diagrams as used in the Forcer program for 4-loop massless propagator diagrams. Most of these features are new.
hep-phPoS(2016)·22 citations
09*
On the equivalence of GPD representations
Dieter Müller🇭🇷 · Kirill Semenov-Tian-Shansky🇷🇺
Phenomenological representations of generalized parton distributions (GPDs) implementing the non-trivial field theoretical requirements are employed in the present day strategies for extracting of hadron structure information encoded in GPDs from the observables of hard exclusive reactions. Showing out the equivalence of various GPD representations can help to get more insight into GPD properties and allow to build up flexible GPD models capable of satisfactory description of the whole set of available experimental data. We review the mathematical aspects of establishing equivalence between the the double partial wave expansion of GPDs in the conformal partial waves and in the $t$ -channel $SO (3)$ partial waves and the double distribution representation of GPDs.
hep-phEPJ Web Conf.(2016)·0 citations
10*
$A_{4}$ and CP symmetry and a model with maximal CP violation
Cai-Chang Li🇨🇳 · Jun-Nan Lu🇨🇳 · Gui-Jun Ding🇨🇳
We study a second CP symmetry compatible with the $A_{4}$ flavor group, which interchanges the representations $1^{'}$ and $1 "$ . We analyze the lepton mixing patterns arising from the $A_{4}$ and CP symmetry broken to residual subgroups $Z_{3}$ and $Z_{2} \times C P$ in the charged lepton and neutrino sectors respectively. One phenomenologically viable mixing pattern is found, and it predicts maximal atmospheric mixing angle as well as maximal Dirac CP phase, trivial Majorana phase and the correlation $sin^{2} θ_{12} cos^{2} θ_{13} = 1/3$ . We construct a concrete model based on the $A_{4}$ and CP symmetry, the above interesting mixing pattern is achieved, the observed charged lepton mass hierarchy is reproduced, and the reactor mixing angle $θ_{13}$ is of the correct order.
hep-phNPB(2016)·38 citations
11*
Precise prediction for the light MSSM Higgs boson mass combining effective field theory and fixed-order calculations
Henning Bahl🇩🇪 · Wolfgang Hollik🇩🇪
In the Minimal Supersymmetric Standard Model heavy superparticles introduce large logarithms in the calculation of the lightest $C P$ -even Higgs boson mass. These logarithmic contributions can be resummed using effective field theory techniques. For light superparticles, however, fixed-order calculations are expected to be more accurate. To gain a precise prediction also for intermediate mass scales, both approaches have to be combined. Here, we report on an improvement of this method in various steps: the inclusion of electroweak contributions, of separate electroweakino and gluino thresholds, as well as resummation at the NNLL level. These improvements can lead to significant numerical effects. In most cases, the lightest $C P$ -even Higgs boson mass is shifted downwards by about 1 GeV. This is mainly caused by higher order corrections to the $MS ˉ$ top-quark mass. We also describe the implementation of the new contributions in the code {\tt FeynHiggs}.
hep-phEPJC(2016)·216 citations
12*
Scattering amplitudes over finite fields and multivariate functional reconstruction
Tiziano Peraro🇬🇧
Several problems in computer algebra can be efficiently solved by reducing them to calculations over finite fields. In this paper, we describe an algorithm for the reconstruction of multivariate polynomials and rational functions from their evaluation over finite fields. Calculations over finite fields can in turn be efficiently performed using machine-size integers in statically-typed languages. We then discuss the application of the algorithm to several techniques related to the computation of scattering amplitudes, such as the four- and six-dimensional spinor-helicity formalism, tree-level recursion relations, and multi-loop integrand reduction via generalized unitarity. The method has good efficiency and scales well with the number of variables and the complexity of the problem. As an example combining these techniques, we present the calculation of full analytic expressions for the two-loop five-point on-shell integrands of the maximal cuts of the planar penta-box and the non-planar double-pentagon topologies in Yang-Mills theory, for a complete set of independent helicity configurations.
hep-phhep-thJHEP(2016)·362 citations
13*
Scalar Fields in Particle Physics
Leonardo Pedro🇵🇹
Extending the scalar sector helps in studying the Higgs mechanism and some Standard Model problems. We implement the correspondence between the gauge-dependent elementary states and the non-perturbative non-abelian gauge-invariant asymptotic states, necessary to study the non-perturbative phenomenology of two-Higgs-doublet models. The Flavour and CP violation in experimental data follows a hierarchical pattern, accounted by the Standard Model. We define the Minimal Flavour Violation condition with six spurions in effective field theories, implying Flavour and CP violation entirely dependent on the fermion mixing matrices but independent of the fermion masses hierarchy; it is renormalization-group invariant. We study the phenomenology of renormalizable two-Higgs-doublet models which verify the defined condition as consequence of a symmetry; new light physical scalars, mediating Flavour Changing Neutral Currents, are allowed by flavour data without flavour coefficients beyond the Standard Model; we tested the models with C++ libraries linked by the symbolic skills of the GiNaC library and we propose more libraries supporting a systematic search for Flavour Changing Neutral Currents. We also map the complex to the real Poincare group representations, derive the free Dirac equation requiring covariant localizability of the representations and study Localization and gauge symmetries in Quantum Field Theory.
hep-ph1 citation
14*
Extending the graviton propagator with a Lorentz-violating vector field
Michael D. Seifert🇺🇸
I discuss progress towards "bootstrapping" a Lorentz-violating gravity theory: namely, extending a linear Lorentz-violating theory of a rank-2 tensor to a non-linear theory by coupling this field to its own stress-energy tensor.
↳ gr-qchep-ph3 citations
15*
Study of the wave packet treatment of neutrino oscillation at Daya Bay
F.P. An🇨🇳 · A.B. Balantekin🇺🇸 · H.R. Band🇺🇸 · M. Bishai🇺🇸 · S. Blyth🇹🇼 · D. Cao · G.F. Cao · J. Cao · W.R. Cen · Y.L. Chan🇨🇳 · J.F. Chang · L.C. Chang and 208 other authors
The disappearance of reactor $ν ˉ_{e}$ observed by the Daya Bay experiment is examined in the framework of a model in which the neutrino is described by a wave packet with a relative intrinsic momentum dispersion $σ_{rel}$ . Three pairs of nuclear reactors and eight antineutrino detectors, each with good energy resolution, distributed among three experimental halls, supply a high-statistics sample of $ν ˉ_{e}$ acquired at nine different baselines. This provides a unique platform to test the effects which arise from the wave packet treatment of neutrino oscillation. The modified survival probability formula was used to fit Daya Bay data, providing the first experimental limits: $2.38 \cdot 1 0^{- 17} < σ_{rel} < 0.23$ . Treating the dimensions of the reactor cores and detectors as constraints, the limits are improved: $1 0^{- 14} ≲ σ_{rel} < 0.23$ , and an upper limit of $σ_{rel} < 0.20$ is obtained. All limits correspond to a 95\% C.L. Furthermore, the effect due to the wave packet nature of neutrino oscillation is found to be insignificant for reactor antineutrinos detected by the Daya Bay experiment thus ensuring an unbiased measurement of the oscillation parameters $sin^{2} 2 θ_{13}$ and $Δ m_{32}^{2}$ within the plane wave model.
↳ hep-exhep-phEPJC(2017)·56 citations
16*
Consistency of Hitomi, XMM-Newton and Chandra 3.5 keV data from Perseus
Joseph P. Conlon🇬🇧 · Francesca Day🇬🇧 · Nicholas Jennings🇬🇧 · Sven Krippendorf🇬🇧 · Markus Rummel🇬🇧
\emph{Hitomi} observations of Perseus with the Soft X-ray Spectrometer (SXS) provide a high-resolution look at the 3.5 keV feature reported by multiple groups in the Perseus cluster. The \emph{Hitomi} spectrum -- which involves the sum of diffuse cluster emission and the point-like central Active Galactic Nucleus (AGN) -- does not show any excess at $E \sim 3.5 keV$ , giving an apparent inconsistency with previous observations of excess diffuse emission. We point out that 2009 \emph{Chandra} data reveals a strong dip in the AGN spectrum at $E = (3.54 \pm 0.02) keV$ (cluster frame) -- the identical energy to the diffuse excess observed by \emph{XMM-Newton}. Scaling this dip to the 2016 AGN luminosity and adding it to the diffuse \emph{XMM-Newton} excess, this predicts an overall dip in the SXS field of view of $(- 5.9 \pm 4.4) \times 1 0^{- 6} ph cm^{- 2} s^{- 1}$ at $E = 3.54$ keV -- a precise match to the \emph{Hitomi} data when broadened by the dark matter virial velocity. We describe models of Fluorescent Dark Matter that can reproduce this physics, in which dark matter absorbs and then re-emits 3.5 keV photons emitted from the central AGN.
↳ astro-ph.HEhep-phPRD(2017)·29 citations
17*
Foreground effect on the $J$ -factor estimation of classical dwarf spheroidal galaxies
Koji Ichikawa🇯🇵 · Miho N. Ishigaki🇯🇵 · Shigeki Matsumoto🇯🇵 · Masahiro Ibe🇯🇵 · Hajime Sugai🇯🇵 · Kohei Hayashi🇯🇵 · Shun-ichi Horigome🇯🇵
The gamma-ray observation of the dwarf spheroidal galaxies (dSphs) is a promising approach to search for the dark matter annihilation (or decay) signal. The dSphs are the nearby satellite galaxies with a clean environment and dense dark matter halo so that they give stringent constraints on the 1 TeV dark matter. However, recent studies have revealed that current estimation of astrophysical factors relevant for the dark matter searches are not conservative, where the various non-negligible systematic uncertainties are not taken into account. Among them, the effect of foreground stars on the astrophysical factors has not been paid much attention, which becomes more important for deeper and wider stellar surveys in the future. In this article, we assess the effects of the foreground contamination by generating the mock samples of stars and using a model of future spectrographs. We investigate various data cuts to optimize the quality of the data and find that the cuts on the velocity and surface gravity can efficiently eliminate the contamination. We also propose a new likelihood function which includes the foreground distribution function. We apply this likelihood function to the fit of the three types of the mock data (Ursa Minor, Draco with large dark matter halo, and Draco with small halo) and three cases of the observation. The likelihood successfully reproduces the input $J$ -factor value while the fit without considering the foreground distribution gives large deviation from the input value by a factor of three.
↳ astro-ph.GAastro-ph.HEhep-phMNRAS(2017)·31 citations
18*
Skewness of elliptic flow fluctuations
Giuliano Giacalone🇫🇷 · Li Yan🇫🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Jean-Yves Ollitrault🇫🇷
Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow ( $v_{2}$ ) in the reaction plane have a negative skew. We compare the skewness of $v_{2}$ fluctuations to that of initial eccentricity fluctuations. We show that skewness is the main effect lifting the degeneracy between higher-order cumulants, with negative skew corresponding to the hierarchy $v_{2} {4} > v_{2} {6}$ observed in Pb+Pb collisions at the LHC. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.
↳ nucl-thhep-phnucl-exPRC(2017)·68 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.