HEP Phenomenology·hep-ph

Thu·May 18, 2017Thursday·May 18, 2017

22 papers—17 primary·5 cross-listed·reconstructed*

01*
First simultaneous extraction of spin-dependent parton distributions and fragmentation functions from a global QCD analysis
J. J. Ethier🇺🇸 · N. Sato🇺🇸 · W. Melnitchouk🇺🇸
We perform the first global QCD analysis of polarized inclusive and semi-inclusive deep-inelastic scattering and single-inclusive $e^{+} e^{-}$ annihilation data, fitting simultaneously the parton distribution and fragmentation functions using the iterative Monte Carlo method. Without imposing SU(3) symmetry relations, we find the strange polarization to be very small, consistent with zero for both inclusive and semi-inclusive data, which provides a resolution to the strange quark polarization puzzle. The combined analysis also allows the direct extraction from data of the isovector and octet axial charges, and is consistent with a small SU(2) flavor asymmetry of the polarized sea.
hep-phhep-exnucl-thPRL(2017)·256 citations
02*
$D \to ρ ℓ^{+} ℓ^{-}$ Decays in the QCD Factorization Approach
Thorsten Feldmann🇩🇪 · Bastian Mueller🇩🇪 · Dirk Seidel🇩🇪
We consider rare semileptonic decays of a heavy $D$ -meson into a light vector meson in the framework of QCD factorization. In contrast to the corresponding $B$ -meson decays, the naive factorization hypothesis does not even serve as a first approximation. Rather, the decay amplitudes appear to be dominated by non-factorizable dynamics, e.g. through annihilation topologies, which are particularly sensitive to long-distance hadronic contributions. We therefore pay particular attention to intermediate vector-meson resonances appearing in quark-loop and annihilation topologies. Compared to the analogous $B$ -meson decays, we identify a number of effects that result in very large theoretical uncertainties for differential decay rates. Some of these effects are found to cancel in the ratio of partially integrated decay rates for transversely and longitudinally polarized $ρ$ mesons. On the phenomenological side this implies a very limited potential to constrain physics beyond the Standard Model by means of these decays.
hep-phhep-exJHEP(2017)·36 citations
03*
The Large N Limit with Vanishing Leading Order Condensate for Zero Pion Mass
Larry McLerran🇺🇸 · Vladimir Skokov🇺🇸
It is conventionally assumed that the negative mass squared term in the linear sigma model version of the pion Lagrangian is $M^{2} \sim Λ_{QCD}^{2}$ in powers of $N_{c}$ . We consider the case where $M^{2} \sim Λ_{QCD}^{2} / N_{c}$ so that to leading order in $N_{c}$ this symmetry breaking term vanishes. We present some arguments why this might be plausible. One might think that such a radical assumption would contradict lattice Monte Carlo data on QCD as function of $N_{c}$ . We show that the linear sigma model gives a fair description of the data of DeGrand and Liu both for $N_{c} = 3$ , and for variable $N_{c}$ . The values of quark masses considered by DeGrand and Liu, and by Bali et. al. turn out to be too large to resolve the case we consider from that of the conventional large $N_{c}$ limit. We argue that for quark masses $m_{q} ≪ Λ_{QCD} / N_{c}^{3/2}$ , both the baryon mass and nucleon size scale as $N_{c}$ . For $m_{q} ≫ Λ_{QCD} / N_{c}^{3/2}$ the conventional large- $N_{c}$ counting holds. The physical values of quark masses for QCD correspond to the small quark mass limit. We find pion-nucleon coupling strengths are reduced to order $O (1)$ rather than $O (N_{c})$ . Under the assumption that in the large $N_{c}$ limit the sigma meson mass is larger than that of the omega, and that the omega-nucleon coupling constant is larger than that of the sigma, we argue that the nucleon-nucleon large range potential is weakly attractive and admits an interaction energy of order $Λ_{QCD} / N_{c}^{5/2} \sim 10$ MeV. With these assumptions on coupling and masses, there is no strong long range attractive channel for nucleon-nucleon interactions, so that nuclear matter at densities much smaller than that where nucleons strongly interact is a weakly interacting configuration of nucleons with strongly interacting localized cores.
hep-phActa Phys.Polon.B(2018)·0 citations
04*
Low energy constituent quark and pion effective couplings in a weak external magnetic field
Fábio L. Braghin🇧🇷
An effective model with pions and constituent quarks in the presence of a weak external background electromagnetic field is derived by starting from a dressed one gluon exchange quark-quark interaction.By applying the auxiliary field and background field methods, the structureless pion limit is considered to extract effective pion and constituent quark couplings in the presence of a weak magnetic field. The leading terms of a large quark and gluon masses expansion are obtained by resolving effective coupling constants which turn out to depend on a weak magnetic field. Two pion field definitions are considered for that. Several relations between the effective coupling constants and parameters can be derived exactly or in the limit of very large quark mass at zero and weak constant magnetic field. Among these ratios, the Gell Mann Oakes Renner and the quark level Goldberger Treiman relations are obtained. In addition to that, in the pion sector, the leading terms of Chiral Perturbation Theory coupled to the electromagnetic field is recovered. Some numerical estimates are provided for the effective coupling constants and parameters.
hep-phhep-thnucl-thEPJA(2018)·19 citations
05*
Electromagnetic properties of neutrinos: three new phenomena in neutrino spin oscillations
Alexande Studenikin🇷🇺
In studies of neutrino electromagnetic properties we discuss three very interesting aspects related to neutrino spin oscillations. First we consider neutrino mixing and oscillations in the mass and flavour bases under the influence of a constant magnetic field with nonzero transversal and longitudinal components. Then we discuss the effect of neutrino spin oscillations induced by electroweak interactions of neutrino with moving matter in case there is matter transversal current or polarization. In the final part of the paper we discuss recently developed approach to description of neutrino spin and spin-flavour oscillations in a constant magnetic field that is based on the use of the exact neutrino stationary states in the magnetic field.
hep-phEPJ Web Conf.(2016)·22 citations
06*
$∣ V_{u d} ∣$ , $∣ V_{u s} ∣$ , $∣ V_{c d} ∣$ , $∣ V_{cs} ∣$ and charm (semi)leptonic decays: WG1 summary from CKM 2016
Takashi Kaneko🇯🇵 · Xiao-Rui Lyu🇨🇳 · Arantza Oyanguren🇪🇸
We summarize the current status of the determination of the CKM matrix elements |V_ud| and |V_us|, which is at the precision frontier of CKM phenomenology. We also review recent progress on the study of charm (semi)leptonic decays, and the determination of |V_cd| and |V_cs|.
hep-phhep-exhep-latPoS(2017)·5 citations
07*
Study on space-time structure of Higgs boson decay using HBT correlation Method in e $^{+}$ e $^{-}$ collision at $s$ =250 GeV
Hong-ge Xu🇨🇳 · Di-kai Li🇨🇳 · Gang Chen🇨🇳 · Liang Li🇨🇳
The space-time structure of the Higgs boson decay are carefully studied with the HBT correlation method using e $^{+}$ e $^{-}$ collision events produced through Monte Carlo generator PYTHIA 8.2 at $s$ =250GeV. The Higgs boson jets (Higgs-jets) are identified by H-tag tracing. The measurement of the Higgs boson radius and decay lifetime are derived from HBT correlation of its decay final state pions inside Higgs-jets in the e $^{+}$ e $^{-}$ collisions events with an upper bound of $R_{H} \leq 1.03 \pm 0.05$ fm and $τ_{H} \leq (1.29 \pm 0.15) \times 1 0^{- 7}$ fs. This result is consistent with CMS data.
hep-phEPJA(2017)·4 citations
08*
NLO electroweak corrections in extended Higgs Sectors with RECOLA2
Ansgar Denner🇩🇪 · Jean-Nicolas Lang🇩🇪 · Sandro Uccirati🇮🇹
We present the computer code RECOLA2 along with the first NLO electroweak corrections to Higgs production in vector-boson fusion and updated results for Higgs strahlung in the Two-Higgs-Doublet Model and Higgs-Singlet extension of the Standard Model. A fully automated procedure for the generation of tree-level and one-loop matrix elements in general models, including renormalization, is presented. We discuss the application of the Background-Field Method to the extended models. Numerical results for NLO electroweak cross sections are presented for different renormalization schemes in the Two-Higgs-Doublet Model and the Higgs-Singlet extension of the Standard Model. Finally, we present distributions for the production of a heavy Higgs boson.
hep-phJHEP(2017)·65 citations
09*
NNLO solution of nonlinear GLR-MQ evolution equation to determine gluon distribution function using Regge like ansatz
P. Phukan🇮🇳 · M. Lalung🇮🇳 · J. K. Sarma🇮🇳
In this work we have suggested a solution of the Gribov-Levin-Ryskin-Mueller-Qiu (GLR-MQ) nonlinear evolution equation at next-to-next-to-leading order (NNLO). The range of $Q^{2}$ in which we have solved the GLR-MQ equation is Regge region of the range $5 G e V^{2} \leq Q^{2} \leq 25 G e V^{2}$ and so we have incorporated the Regge like behavior to obtain $Q^{2}$ evolution of gluon distribution function $G (x, Q^{2})$ . We have also checked the sensitivity of our results for different values of correlation radius (R) between two interacting gluons, viz. $R = 2 G e V^{- 1}$ and $R = 5 G e V^{- 1}$ as well as for different values of Regge intercept $λ_{G}$ . Our computed results are compared with those obtained by the most recent global DGLAP fits to the parton distribution functions viz. PDF4LHC15, NNPDF3.0, HERAPDF15, CT14 and ABM12.
hep-phNPA(2017)·21 citations
10*
Gauging Lepton Flavour
P. Quilez🇪🇸
The flavour lepton symmetry is gauged for both the Standard Model flavor group and its extension with three degenerate right-handed neutrinos. As a consequence of anomaly cancellation, exotic leptons are introduced which induce a see-saw mechanism that generates the masses of the SM leptons. The model is compared with Minimal Flavour Violation, the difference between the low-energy effective operators resulting is identified, as well as the distinctive experimental signals, particularly promising in the $μ - τ$ sector.
hep-ph1 citation
11*
Quasigluon lifetime and confinement from first principles
Fabio Siringo🇮🇹
The mass and the lifetime of a gluon are evaluated from first principles at finite temperature across the deconfinement transition of pure SU(3) Yang-Mills theory, by a direct calculation of the pole of the propagator in the complex plane, using the finite temperature extension of a massive expansion in the Landau gauge. Even at T=0 the quasigluon lifetime is finite and the gluon is canceled from the asymptotic states, yielding a microscopic proof of confinement from first principles. Above the transition the damping rate is a linear increasing function of temperature as predicted by standard perturbation theory.
hep-phhep-lathep-thPRD(2017)·21 citations
12*
Three-body universality in the B meson sector
Yong-Hui Lin🇨🇳 · Erik Wilbring🇩🇪 · Hai-Long Fu🇨🇳 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪
The charged exotic mesons Z_b(10610) and Z'_b(10650) observed by the Belle collaboration in 2011 are very close to the B* Bbar and B* Bbar* thresholds, respectively. This suggests their interpretation as shallow hadronic molecules of B and B* mesons. Using the masses of the Z_b(10610) and Z'_b(10650) as input, we rule out the possibility for universal bound states of three B and B* mesons arising from the Efimov effect based on their spin-isospin structure. As a consequence, we can predict the phase shifts for the scattering of B and B* mesons off the exotic mesons Z_b(10610) and Z'_b(10650) to leading order in a non-relativistic effective field theory with contact interactions based on two-body information alone.
hep-phcond-mat.quant-gasJ.Phys.G(2025)·12 citations
13*
Comparison of two Minkowski-space approaches to heavy quarkonia
Sofia Leitão🇵🇹 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · M. T. Peña🇵🇹 · Alfred Stadler🇵🇹 · James P. Vary🇺🇸 · Elmar P. Biernat🇵🇹
In this work we compare mass spectra and decay constants obtained from two recent, independent, and fully relativistic approaches to the quarkonium bound-state problem: the Hamiltonian basis light-front quantization (BLFQ) approach, where light-front wave functions are naturally formulated; and, the covariant spectator theory (CST), based on a reorganization of the Bethe-Salpeter equation. Even though conceptually different, both solutions are obtained in Minkowski space. Comparisons of decay constants for more than ten states of charmonium and bottomonium show favorable agreement between the two approaches as well as with experiment where available. We also apply the Brodsky-Huang-Lepage prescription to convert the CST amplitudes into functions of light-front variables. This provides an ideal opportunity to investigate the similarities and differences at the level of the wave functions. Several qualitative features are observed in remarkable agreement between the two approaches even for the rarely addressed excited states. Leading twist distribution amplitudes as well as parton distribution functions of heavy quarkonia are also analyzed.
hep-phnucl-thEPJC(2017)·34 citations
14*
Self-interacting dark matter as a solution to the problems in small-scale structures
Camilo Garcia-Cely🇧🇪 · Xiaoyong Chu🇦🇹
Dark matter self-interactions are a well-motivated solution to the core-vs.-cusp and the too-big-to-fail problems. They are commonly induced by means of a light mediator, that is also responsible for the dark matter freeze-out in the early universe. Motivated by the fact that such scenario is excluded in its simplest realizations, we will discuss the possibility that the relic density of a self-interacting dark matter candidate can proceed from the freeze-out of only annihilations into SM particles. We will argue that scalar and Majorana dark matter in the mass range of 10 to 500 MeV, coupled to a slightly heavier massive gauge boson, are the only candidates in agreement with multiple current experimental constraints. We will also discuss prospects of establishing or excluding these two scenarios in future experiments.
hep-ph10 citations
15*
Algorithmic transformation of multi-loop master integrals to a canonical basis with CANONICA
Christoph Meyer🇩🇪
The integration of differential equations of Feynman integrals can be greatly facilitated by using a canonical basis. This paper presents the Mathematica package CANONICA, which implements a recently developed algorithm to automatize the transformation to a canonical basis. This represents the first publicly available implementation suitable for differential equations depending on multiple scales. In addition to the presentation of the package, this paper extends the description of some aspects of the algorithm, including a proof of the uniqueness of canonical forms up to constant transformations.
hep-phComput.Phys.Commun.(2018)·188 citations
16*
On lepton non-universality in exclusive $b \to s ℓℓ$ decays
T. Hurth🇩🇪 · F. Mahmoudi🇫🇷 · D. Martinez Santos🇪🇸 · S. Neshatpour🇮🇷
The LHCb measurements of certain ratios of decay modes testing lepton flavour non-universality might open an exciting world of new physics beyond the standard model. The latest LHCb measurements of R_K* offer some new insight beyond the previous measurement of R_K. We work out the present significance for non-universality, and argue that claims of 5 sigma deviations from the SM based on all present b -> s l+l- data including the ratios are misleading and are at present still based on guesstimates of hadronic power corrections in the b -> s l+l- angular observables. We demonstrate that only a small part of the luminosity of 50 fb^-1 foreseen to be accumulated by the LHCb will be needed to offer soon a definite answer to the present question whether we see a very small glimpse of lepton flavour non-universal new physics or not. We also present new predictions for other ratios based on our analysis of the present measurements of the ratios R_K^(*) and analyse if they are able to differentiate between various new physics options within the effective field theory at present or in the near future.
hep-phPRD(2017)·113 citations
17*
Detection prospects of light pseudoscalar Higgs boson at the LHC
Monoranjan Guchait🇮🇳 · Aravind H. Vijay🇮🇳 · Jacky Kumar🇮🇳
The discovery potential of light pseudo scalar Higgs boson for the mass range 10-60 GeV is explored. In the context of the next-to-minimal supersymmetric standard(NMSSM) model, the branching fraction of light pseudo scalar Higgs boson decaying to a pair of photon can be quite large. A pair of light pseudo scalar Higgs boson produced indirectly through the standard model Higgs boson decay yields multiple photons in the final state and the corresponding production rate is restricted by ATLAS data. Discussing the impact of this constraint in the NMSSM, the detection prospects of light pseudoscalar Higgs boson in the channel consisting of at least three photons, a lepton and missing transverse energy are reported. It is observed that the possibilities of finding the pseudoscalar Higgs boson for the above mass range are promising for an integrated luminosity $L = 100 fb^{- 1}$ with moderate significances, which can reach to more than 5 $σ$ for higher luminosity options.
hep-phJHEP(2017)·5 citations
18*
Improved constraints on monopole-dipole interaction mediated by pseudo-scalar bosons
N. Crescini🇮🇹 · C. Braggio🇮🇹 · G. Carugno🇮🇹 · P. Falferi🇮🇹 · A. Ortolan🇮🇹 · G. Ruoso🇮🇹
We present a more stringent upper limit on long-range axion-mediated forces obtained by the QUAX-g $_{p}$ g $_{s}$ experiment, located at the INFN - Laboratori Nazionali di Legnaro. We investigate the possible coupling between the electron spins of a paramagnetic GSO crystal and unpolarized nucleons of lead disks by measuring variations of GSO magnetization with a dc-SQUID magnetometer. Such an induced magnetization can be interpreted as the effect of a long-range spin dependent interaction mediated by axions or Axion Like Particles (ALPs). The corresponding coupling strength is proportional to the CP violating term $g_{p}^{e} g_{s}^{N}$ , i.e. the product of the pseudoscalar and scalar coupling constants of electron and nucleon, respectively. Previous upper limits are improved by one order of magnitude, namely $g_{p}^{e} g_{s}^{N} / (ℏ c) \leq 4.3 \times 1 0^{- 30}$ at 95% confidence level, in the interaction range $1 0^{- 3}$ m $< λ_{a} < 0.2$ m. We eventually discuss our plans to improve the QUAX-g $_{p}$ g $_{s}$ sensitivity by a few orders of magnitude, which will allow us to investigate the $ϑ ≃ 1 0^{- 10}$ range of CP-violating parameter and test some QCD axion models.
↳ hep-exhep-phPLB(2017)·60 citations
19*
Coarse graining of NN inelastic interactions up to 3 GeV:Repulsive vs Structural core
P. Fernandez-Soler🇪🇸 · E. Ruiz Arriola🇪🇸
The repulsive short distance core is one of the main paradigms of nuclear physics which even seems confirmed by QCD lattice calculations. On the other hand nuclear potentials at short distances are motivated by high energy behavior where inelasticities play an important role. We analyze NN interactions up to 3 GeV in terms of simple coarse grained complex and energy dependent interactions. We discuss two possible and conflicting scenarios which share the common feature of a vanishing wave function at the core location in the particular case of S- waves. We find that the optical potential with a repulsive core exhibits a strong energy dependence whereas the optical potential with the structural core is characterized by a rather adiabatic energy dependence which allows to treat inelasticity perturbatively. We discuss the possible implications for nuclear structure calculations of both alternatives.
↳ nucl-thhep-phPRC(2017)·9 citations
20*
Iso-vector axial form factors of the nucleon in two-flavour lattice QCD
Stefano Capitani🇩🇪 · Michele Della Morte🇩🇰 · Dalibor Djukanovic🇩🇪 · Georg M. von Hippel🇩🇪 · Jiayu Hua🇩🇪 · Benjamin Jäger🇬🇧 · Parikshit M. Junnarkar🇮🇳 · Harvey B. Meyer🇩🇪 · Thomas D. Rae🇩🇪 · Hartmut Wittig🇩🇪
We present a lattice calculation of the nucleon iso-vector axial and induced pseudoscalar form factors on the CLS ensembles using $N_{f} = 2$ dynamical flavours of non-perturbatively $O (a)$ -improved Wilson fermions and an $O (a)$ -improved axial current together with the pseudoscalar density. Excited-state effects in the extraction of the form factors are treated using a variety of methods, with a detailed discussion of their respective merits. The chiral and continuum extrapolation of the results is performed both using formulae inspired by Heavy Baryon Chiral Perturbation Theory (HBChPT) and a global approach to the form factors based on a chiral effective theory (EFT) including axial vector mesons. Our results indicate that careful treatment of excited-state effects is important in order to obtain reliable results for the axial form factors of the nucleon, and that the main remaining error stems from the systematic uncertainties of the chiral extrapolation. As final results, we quote $g_{A} = 1.278 \pm 0.068 - 0.087 + 0.000$ , $⟨ r_{A}^{2} ⟩ = 0.360 \pm 0.036 - 0.088 + 0.080 fm^{2}$ , and $g_{P} = 7.7 \pm 1.8 - 2.0 + 0.8$ for the axial charge, axial charge radius and induced pseudoscalar charge, respectively, where the first error is statistical and the second is systematic.
↳ hep-lathep-phnucl-thInt.J.Mod.Phys.A(2019)·97 citations
21*
Single Field Double Inflation and Primordial Black Holes
Kristjan Kannike🇪🇪 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪 · Hardi Veermäe🇪🇪
Within the framework of scalar-tensor theories, we study the conditions that allow single field inflation dynamics on small cosmological scales to significantly differ from that of the large scales probed by the observations of cosmic microwave background. The resulting single field double inflation scenario is characterised by two consequent inflation eras, usually separated by a period where the slow-roll approximation fails. At large field values the dynamics of the inflaton is dominated by the interplay between its non-minimal coupling to gravity and the radiative corrections to the inflaton self-coupling. For small field values the potential is, instead, dominated by a polynomial that results in a hilltop inflation. Without relying on the slow-roll approximation, which is invalidated by the appearance of the intermediate stage, we propose a concrete model that matches the current measurements of inflationary observables and employs the freedom granted by the framework on small cosmological scales to give rise to a sizeable population of primordial black holes generated by large curvature fluctuations. We find that these features generally require a potential with a local minimum. We show that the associated primordial black hole mass function is only approximately lognormal.
↳ astro-ph.COhep-phJCAP(2017)·323 citations
22*
Cooling Stochastic Quantization with colored noise
Jan M. Pawlowski🇩🇪 · Ion-Olimpiu Stamatescu🇩🇪 · Felix P.G. Ziegler🇩🇪
Smoothing of field configurations is highly important for precision calculations of physical quantities on the lattice. We present a cooling method based on Stochastic Quantization with a built-in UV momentum cutoff. The latter is implemented via a UV-regularized, hence colored, noise term. Our method is tested in a two-dimensional scalar field theory. We show, that UV modes can be removed systematically without altering the physics content of the theory. The approach has an interpretation in terms of the non-perturbative (Wilsonian) renormalization group that facilitates the physics interpretation of the cutoff procedure. It also can be used to define the maximal colored cooling applicable without changing the theory.
↳ hep-lathep-phhep-thPRD(2017)·18 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.