HEP Phenomenology·hep-ph

Thu·May 25, 2017Thursday·May 25, 2017

19 papers—15 primary·4 cross-listed·reconstructed*

01*
Dark Energy from pNGB Mediated Dirac Neutrino Condensate
Ujjal Kumar Dey🇮🇳 · Tirtha Sankar Ray🇮🇳 · Utpal Sarkar🇮🇳
We consider an extension of the Standard Model that provide an unified description of eV scale neutrino mass and dark energy. An explicit model is presented by augmenting the Standard Model with an $S U (2)_{L}$ doublet scalar, a singlet scalar and right handed neutrinos where all of them are assumed to be charged under a global $U (1)_{X}$ symmetry. A light pseudo-Nambu-Goldstone Boson, associated with the spontaneously broken $U (1)_{X}$ symmetry, acts as a mediator of an attractive force leading to a Dirac neutrino condensate, with large correlation length, and a non-zero gap in the right range providing a cosmologically feasible dark energy scenario. The neutrino mass is generated through the usual Dirac seesaw mechanism. Parameter space, reproducing viable dark energy scenario while having neutrino mass in the right ballpark, is presented.
hep-phastro-ph.CONPB(2018)·5 citations
02*
Search for the Footprints of New Physics with Laboratory and Cosmic Neutrinos
Floyd W. Stecker🇺🇸
Observations of high energy neutrinos, both in the laboratory and from cosmic sources, can be a useful probe in searching for new physics. Such observations can provide sensitive tests of Lorentz invariance violation (LIV), which may be a the result of quantum gravity physics (QG). We review some observationally testable consequences of LIV using effective field theory (EFT) formalism. To do this, one can postulate the existence of additional small LIV terms in free particle Lagrangians, suppressed by powers of the Planck mass. The observational consequences of such terms are then examined. In particular, one can place limits on a class of non-renormalizable, mass dimension five and six Lorentz invariance violating operators that may be the result of QG.
hep-phastro-ph.HEgr-qcMod.Phys.Lett.A(2017)·1 citation
03*
FCNC Decays of the Top Quark
Debjyoti Bardhan🇮🇳
If new physics (e.g. SUSY) does not show up as direct evidence at the LHC, it could still be observable in FCNC processes involving the $t$ -quark. We take a close look at the process $t \to c + h / Z$ and show that its branching ratio in the Standard Model is subject to three mechanisms of suppression. To obtain an observable signal, one needs to evade all these mechanisms in a theory beyond the Standard Model. We show that a theory like the cMSSM cannot provide a big enough enhancement. However, in a framework like $R$ -parity-violating SUSY, observable signals are a distinct possibility.
hep-phPoS(2017)·4 citations
04*
The observed $Ω_{c}^{0}$ resonances as pentaquark states
C. S. An🇨🇳 · H. Chen🇨🇳
In present work, we investigate the spectrum of several low-lying $ssc q q ˉ$ pentaquark configurations employing the constituent quark model, within which the hyperfine interaction between quarks is taken to be mediated by Goldstone boson exchange. Our numerical results show that four $ssc q q ˉ$ configurations with $J^{P} = 1/ 2^{-}$ or $J^{P} = 3/ 2^{-}$ lie at energies very close to the recently observed five $Ω_{c}^{0}$ states by LHCb collaboration, this indicates that the $ssc q q ˉ$ pentaquark configurations may form sizable components of the observed $Ω_{c}^{0}$ resonances.
hep-phPRD(2017)·60 citations
05*
Testing violation of the Leggett-Garg-type inequality in neutrino oscillations of the Daya Bay experiment
Qiang Fu🇨🇳 · Xurong Chen🇨🇳
The Leggett-Garg inequality (LGI), derived under the assumption of realism, acts as the temporal Bell's inequality. It is studied in electromagnetic and strong interaction like photonics, superconducting qu-bits and nuclear spin. Until the weak interaction two-state oscillations of neutrinos affirmed the violation of Leggett-Garg-type inequalities (LGtI). We make an empirical test for the deviation of experimental results with the classical limits by analyzing the survival probability data of reactor neutrinos at a distinct range of baseline dividing energies, as an analog to a single neutrino detected at different time. A study of the updated data of Daya-Bay experiment unambiguously depicts an obvious cluster of data over the classical bound of LGtI and shows a $6.1 σ$ significance of the violation of them.
hep-phhep-exEPJC(2017)·47 citations
06*
Boost invariant formulation of the chiral kinetic theory
Shu Ebihara🇯🇵 · Kenji Fukushima🇯🇵 · Shi Pu🇯🇵
We formulate the chiral kinetic equation with the longitudinal boost invariance. We particularly focus on the physical interpretation of the particle number conservation. There appear two terms associated with the expansion, which did not exist in the non-chiral kinetic equation. One is a contribution to the transverse current arising from the side-jump effect, and the other is a change in the density whose flow makes the longitudinal current. We point out a characteristic pattern in the transverse current driven by the expansion, which we call the chiral circular displacement.
hep-phPRD(2017)·24 citations
07*
Manifestations of the $a_{0}^{0} (980) - f_{0} (980)$ mixing in $D^{0} \to K_{S}^{0} π^{+} π^{-}$ and $D^{0} \to K_{S}^{0} η π^{0}$ decays
N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺
Possible manifestations of the isospin-breaking mixing of the $a_{0}^{0} (980)$ and $f_{0} (980)$ resonances are analyzed in the $D^{0} \to K_{S}^{0} π^{+} π^{-}$ and $D^{0} \to K_{S}^{0} η π^{0}$ decays. It is shown that the $a_{0}^{0} (980) - f_{0} (980)$ mixing has the most influence on the $π^{+} π^{-}$ mass spectrum in the decay $D^{0} \to K_{S}^{0} π^{+} π^{-}$ . Owing to the $a_{0}^{0} (980) - f_{0} (980)$ mixing, the $f_{0} (980)$ peak in $D^{0} \to K_{S}^{0} f_{0} (980) \to K_{S}^{0} π^{+} π^{-}$ can experience distortions comparable with its size. The effect essentially depends on the relative phase between the amplitudes of the $D^{0} \to K_{S}^{0} f_{0} (980)$ and $D^{0} \to K_{S}^{0} a_{0}^{0} (980)$ transitions.
hep-phhep-exnucl-thPRD(2017)·12 citations
08*
Lepton Flavor Changing Higgs decays in the Littlest Higgs Model with T-parity
F. del Aguila🇪🇸 · Ll. Ametller🇪🇸 · J.I. Illana🇪🇸 · J. Santiago🇪🇸 · P. Talavera🇪🇸 · R. Vega-Morales🇪🇸
We calculate loop induced lepton flavor violating Higgs decays in the Littlest Higgs model with T-parity. We find that a finite amplitude is obtained only when all contributions from the T-odd lepton sector are included. This is in contrast to lepton flavor violating processes mediated by gauge bosons where the partners of the right-handed mirror leptons can be decoupled from the spectrum. These partners are necessary to cancel the divergence in the Higgs mass introduced by the mirror leptons but are otherwise unnecessary and assumed to be decoupled in previous phenomenological studies. Furthermore, as we emphasize, including the partner leptons in the spectrum also introduces a new source of lepton flavor violation via their couplings to the physical pseudo-Goldstone electroweak triplet scalar. Although this extra source also affects lepton flavor changing gauge transitions, it decouples from these amplitudes in the limit of heavy mass for the partner leptons. We find that the corresponding Higgs branching ratio into taus and muons can be as large as $\sim 0.2 \times 1 0^{- 6}$ for T-odd masses of the order a few TeV, a demanding challenge even for the high luminosity LHC.
hep-phJHEP(2017)·20 citations
09*
Photon and Pomeron -- induced production of Dijets in $pp$ , $p A$ and $AA$ collisions
E. Basso🇧🇷 · V. P. Goncalves🇧🇷 · A. K. Kohara🇧🇷 · M. S. Rangel🇧🇷
In this paper we present a detailed comparison of the dijet production by photon -- photon, photon -- pomeron and pomeron -- pomeron interactions in $pp$ , $p A$ and $AA$ collisions at the LHC energy. The transverse momentum, pseudo -- rapidity and angular dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows to obtain realistic predictions for the dijet production with two leading intact hadrons. We obtain that $γ \pom$ channel is dominant at forward rapidities in $pp$ collisions and in the full kinematical range in the nuclear collisions of heavy nuclei. Our results indicate that the analysis of dijet production at the LHC can be useful to test the Resolved Pomeron model as well as to constrain the magnitude of the absorption effects.
hep-phhep-exnucl-exnucl-thEPJC(2017)·20 citations
10*
Low x gluons determined by open charm production
E.G. de Oliveira🇧🇷 · A.D. Martin🇬🇧 · M.G. Ryskin🇬🇧
We use the LHCb data on the forward production of $D$ mesons at 7, 13 and 5 TeV to make a direct determination of the gluon distribution, $xg$ , at NLO in the $1 0^{- 5} ≲ x ≲ 1 0^{- 4}$ region. We first use a simple parametrization of the gluon density in each of the four transverse momentum intervals of the detected $D$ mesons. Second, we use a double log parametrization to make a combined fit to all the LHCb $D$ meson data. The values found for $xg$ in the above $x$ domain are of the similar magnitude (or a bit larger) than the central values of extrapolations of the gluons obtained by the global PDF analyses into this small $x$ region. However, in contrast, we find $xg$ has a weak dependence on $x$ .
hep-ph6 citations
11*
Running of the Charm-Quark Mass from HERA Deep-Inelastic Scattering Data
A.Gizhko🇩🇪 · A.Geiser🇩🇪 · S.Moch🇩🇪 · I.Abt🇩🇪 · O.Behnke🇩🇪 · A.Bertolin🇮🇹 · J.Blümlein🇩🇪 · D.Britzger🇩🇪 · R.Brugnera🇮🇹 · A.Buniatyan🇬🇧 · P.J.Bussey🇬🇧 · R.Carlin🇮🇹 and 38 other authors
Combined HERA data on charm production in deep-inelastic scattering have previously been used to determine the charm-quark running mass $m_{c} (m_{c})$ in the MSbar renormalisation scheme. Here, the same data are used as a function of the photon virtuality $Q^{2}$ to evaluate the charm-quark running mass at different scales to one-loop order, in the context of a next-to-leading order QCD analysis. The scale dependence of the mass is found to be consistent with QCD expectations.
hep-phPLB(2017)·31 citations
12*
Bondi accretion of dark matter by neutron stars
Xi Huang🇨🇳 · Jian-Feng Liu🇨🇳 · Wei-Hua Wang🇨🇳 · Quan Cheng🇨🇳 · Xiao-Ping Zheng🇨🇳
In this paper, we have compared two different accretion mechanisms of dark matter particles by a canonical neutron star with $M = 1.4 M_{⊙}$ and $R = 10 km$ , and shown the effects of dark matter heating on the surface temperature of star. We should take into account the Bondi accretion of dark matter by neutron stars rather than the accretion mechanism of Kouvaris (2008) \citep{Kouvaris08}, once the dark matter density is higher than $\sim 3.81 GeV/c m^{3}$ . Based on the Bondi accretion mechanism and heating of dark matter annihilation, the surface temperature platform of star can appear at $\sim 1 0^{6.5}$ year and arrive $\sim 1.12 \times 1 0^{5}$ K for the dark matter density of $3.81 GeV/c m^{3}$ , which is one order of magnitude higher than the case of Kouvaris (2008) with dark matter density of $30 GeV/c m^{3}$ .
hep-ph2 citations
13*
Higgs Boson Decays to Dark Photons through the Vectorized Lepton Portal
Qianshu Lu🇨🇦 · David E. Morrissey🇨🇦 · Alexander M. Wijangco🇨🇦
Vector-like fermions charged under both the Standard Model and a new dark gauge group arise in many theories of new physics. If these fermions include an electroweak doublet and singlet with equal dark charges, they can potentially connect to the Higgs field through a Yukawa coupling in analogy to the standard neutrino portal. With such a coupling, fermion loops generate exotic decays of the Higgs boson to one or more dark vector bosons. In this work we study a minimal realization of this scenario with an Abelian dark group. We investigate the potential new Higgs decays modes, we compute their rates, and we study the prospects for observing them at the Large Hadron Collider and beyond given the other experimental constraints on the theory. We also discuss extensions of the theory to non-Abelian dark groups.
hep-phJHEP(2017)·16 citations
14*
Top-quark pair-production and decay at high precision
Jun Gao🇨🇳 · Andrew S. Papanastasiou🇬🇧
We present a fully-differential and high-precision calculation of top-quark pair-production and decay at the LHC, providing predictions for observables constructed from top-quark leptonic and $b$ -flavoured jet final states. The calculation is implemented in a parton-level Monte Carlo and includes an approximation to the next-to-next-to leading order (NNLO) corrections to the production and, for the first time, the exact NNLO corrections to the decay subprocesses. The corrections beyond NLO are sizeable, and including them is crucial for an accurate description of the cross section constrained by experimental phase-space restrictions. We compare our predictions to published ATLAS and CMS measurements at the LHC, finding improved agreement compared with lower orders in the perturbative expansion.
hep-phhep-exPRD(2017)·45 citations
15*
A variant of 3-3-1 model for the generation of the SM fermion mass and mixing pattern
A. E. Cárcamo Hernández🇨🇱 · Sergey Kovalenko🇨🇱 · H. N. Long🇻🇳 · Ivan Schmidt🇨🇱
We propose an extension of the 3-3-1 model with an additional symmetry group $Z_{2} \times Z_{4} \times U (1)_{L_{g}}$ and an extended scalar sector. To our best knowledge this is the first example of a renormalizable 3-3-1 model, which allows explanation of the SM fermion mass hierarchy by a sequential loop suppression: tree-level top and exotic fermion masses, 1-loop bottom, charm, tau and muon masses; 2-loop masses for the light up, down, strange quarks as well as for the electron. The light active neutrino masses are generated from a combination of linear and inverse seesaw mechanisms at two loop level. The model also has viable fermionic and scalar dark matter candidates.
hep-phJHEP(2018)·57 citations
16*
Effect of finite particle number sampling on baryon number fluctuations
Jan Steinheimer🇩🇪 · Volker Koch🇺🇸
The effects of finite particle number sampling on the net baryon number cumulants, extracted from fluid dynamical simulations, are studied. The commonly used finite particle number sampling procedure introduces an additional Poissonian (or multinomial if global baryon number conservation is enforced) contribution which increases the extracted moments of the baryon number distribution. If this procedure is applied to a fluctuating fluid dynamics framework one severely overestimates the actual cumulants. We show that the sampling of so called test-particles suppresses the additional contribution to the moments by at least one power of the number of test-particles. We demonstrate this method in a numerical fluid dynamics simulation that includes the effects of spinodal decomposition due to a first order phase transition. Furthermore, in the limit where anti-baryons can be ignored, we derive analytic formulas which capture exactly the effect of particle sampling on the baryon number cumulants. These formulas may be used to test the various numerical particle sampling algorithms.
↳ nucl-thhep-phPRC(2017)·19 citations
17*
On beam models and their paraxial approximation
W. J. Waters🇬🇧 · B. King🇬🇧
We derive focused laser pulse solutions to the electromagnetic wave equation in vacuum. After reproducing beam and pulse expressions for the well-known paraxial Gaussian and axicon cases, we apply the method to analyse a laser beam with Lorentzian transverse momentum distribution. Whilst a paraxial approach has some success close to the focal axis and within a Rayleigh range of the focal spot, we find that it incorrectly predicts the transverse fall-off typical of a Lorentzian. Our vector-potential approach is particularly relevant to calculation of quantum electrodynamical processes in weak laser pulse backgrounds.
↳ physics.opticshep-phphysics.class-phLaser Phys.(2018)·10 citations
18*
Conjoined constraints on modified gravity from the expansion history and cosmic growth
Spyros Basilakos🇬🇷 · Savvas Nesseris🇪🇸
In this paper we present conjoined constraints on several cosmological models from the expansion history $H (z)$ and cosmic growth $f σ_{8} (z)$ . The models we study include the CPL $w_{0} w_{a}$ parametrization, the Holographic Dark Energy (HDE) model, the Time varying vacuum ( $Λ_{t}$ CDM) model, the Dvali, Gabadadze and Porrati (DGP) and Finsler-Randers (FRDE) models, a power law $f (T)$ model and finally the Hu-Sawicki $f (R)$ model. In all cases we perform a simultaneous fit to the SnIa, CMB, BAO, $H (z)$ and growth data, while also following the conjoined visualization of $H (z)$ and $f σ_{8} (z)$ as in Linder (2017). Furthermore, we introduce the Figure of Merit (FoM) in the $H (z) - f σ_{8} (z)$ parameter space as a way to constrain models that jointly fit both probes well. We use both the latest $H (z)$ and $f σ_{8} (z)$ data, but also LSST-like mocks with $1%$ measurements and we find that the conjoined method of constraining the expansion history and cosmic growth simultaneously is able not only to place stringent constraints on these parameters but also to provide an easy visual way to discriminate cosmological models. Finally, we confirm the existence of a tension between the growth rate and Planck CMB data and we find that the FoM in the conjoined parameter space of $H (z) - f σ_{8} (z)$ can be used to discriminate between the $Λ$ CDM model and certain classes of modified gravity models, namely the DGP and $f (T)$ .
↳ astro-ph.COgr-qchep-phPRD(2017)·74 citations
19*
Wandering in the Lyman-alpha Forest: A Study of Dark Matter-Dark Radiation Interactions
Rebecca Krall🇺🇸 · Francis-Yan Cyr-Racine🇺🇸 · Cora Dvorkin🇺🇸
The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provides no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of $2Δ ln L = 12$ with respect to the standard $Λ$ cold dark matter ( $Λ$ CDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to $2Δ ln L = 6$ relative to $Λ$ CDM. We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, $Δ N_{fluid}$ , will be improved by an order of magnitude compared to current bounds.
↳ astro-ph.COhep-phJCAP(2017)·45 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.