Wed·Aug 17, 2016Wednesday·August 17, 2016

1. 01*

   Neutrino assisted GUT baryogenesis - revisited

   Wei-Chih Huang🇩🇪 · Heinrich Päs🇩🇪 · Sinan Zeissner🇩🇪

   Many GUT models conserve the difference between the baryon and lepton number, $B-L$. These models can create baryon and lepton asymmetries from heavy Higgs or gauge boson decays with $B+L\ne 0$ but with $B-L=0$. Since the sphaleron processes violate $B+L$, such GUT-generated asymmetries will finally be washed out completely, making GUT baryogenesis scenarios incapable of reproducing the observed baryon asymmetry of the Universe. In this work, we revisit the idea to revive GUT baryogenesis, proposed by Fukugita and Yanagida, where right-handed neutrinos erase the lepton asymmetry before the sphaleron processes can significantly wash out the original $B+L$ asymmetry, and in this way one can prevent a total washout of the initial baryon asymmetry. By solving the Boltzmann equations numerically for baryon and lepton asymmetries in a simplified 1+1 flavor scenario, we can confirm the results of the original work. We further generalize the analysis to a more realistic scenario of three active and two right-handed neutrinos to highlight flavor effects of the right-handed neutrinos. Large regions in the parameter space of the Yukawa coupling and the right-handed neutrino mass featuring successful baryogenesis are identified.

   hep-phPRD(2018)·8 citations
2. 02*

   Constraining the Higgs couplings to up and down quarks using production kinematics at the CERN Large Hadron Collider

   Gage Bonner🇨🇦 · Heather E. Logan (Carleton U.)🇨🇦

   We study the prospects for constraining the Higgs boson's couplings to up and down quarks using kinematic distributions in Higgs production at the CERN Large Hadron Collider. We find that the Higgs $p_T$ distribution can be used to constrain these couplings with precision competitive to other proposed techniques. With 3000 fb${}^{-1}$ of data at 13 TeV in the four-lepton decay channel, we find $-0.73\lesssim {\bar{\kappa }}_u\lesssim 0.33$ and $-0.88\lesssim {\bar{\kappa }}_d\lesssim 0.32$, where ${\bar{\kappa }}_q=(m_q/m_b){\kappa }_q$ is a scaling factor that modifies the $q$ quark Yukawa coupling relative to the Standard Model bottom quark Yukawa coupling. The sensitivity may be improved by including additional Higgs decay channels.

   hep-phhep-ex27 citations
3. 03*

   Hadronic matter at the edge: A survey of some theoretical approaches to the physics of the QCD phase diagram

   Alejandro Ayala🇲🇽

   In the past few years a wealth of high quality data has made possible to test current theoretical ideas about the properties of hadrons subject to extreme conditions of density and temperature. The relativistic heavy-ion program carried out at the CERN-SPS and under development at the BNL-RHIC and CERN-LHC has provided results that probe the evolution of collisions of hadronic matter at high energies from the initially large density to the late dilute stages. In addition, QCD on the lattice has produced results complementing these findings with first principles calculations for observables in a regime where perturbative techniques cannot describe the nature of strongly coupled systems. This work aims to review some recent developments that make use of field theoretical methods to describe the physics of hadrons at finite temperature and density. I concentrate on two of the main topics that have been explored in the last few years: (1) The search for the structure of the phase diagram and (2) analytical signals linked to the chiral symmetry restoration/deconfinement.

   hep-phhep-latnucl-thJ.Phys.Conf.Ser.(2016)·3 citations
4. 04*

   Phenomenology of Dihadron Fragmentation Function

   A. Courtoy🇲🇽

   We report on the phenomenological results obtained through Dihadron Fragmentation Functions related processes. In 2015, an update on the fitting techniques for the Dihadron Fragmentation Functions has led to an improved extraction of the transversity PDF and, as a consequence, the nucleon tensor charge. We discuss the impact of the determination of the latter on search for physics Beyond the Standard Model, focusing on the error treatment. We also comment on the future of the extraction of the subleading-twist PDF $e(x)$ from JLab soon-to-be-released Beam Spin Asymmetry data.

   hep-phJ.Phys.Conf.Ser.(2016)·0 citations
5. 05*

   Calculation of 1/m^{2}_{b} corrections to {\Lambda}_b\rightarrow{\Lambda}_c decay widths in the Bethe-Salpeter equation approach

   L. Zhang🇨🇳 · X.-H. Guo🇨🇳 · M.-H. Weng🇨🇳

   The matrix element of the weak transition {\Lambda}_b\rightarrow{\Lambda}_c can be expressed in terms of six form factors. {\Lambda}_Q(Q = b;c) can be regarded as composed of a heavy quark Q(Q = b;c) and a diquark which is made up of the remaining two light quarks. In this picture, we express these six form factors in terms of Bethe-Salpeter wave functions to second order in the 1/m_Q expansion. With the kernel containing both the scalar confinement and the one-gluon-exchange terms we calculate the form factors and the decay widths of the semileptonic decay {\Lambda}_b\rightarrow{\Lambda}_clv as well as nonleptonic decays {\Lambda}_b\rightarrow{\Lambda}_cP(V) numerically. We also add QCD corrections since they are comparable with 1/m_Q corrections.

   hep-ph0 citations
6. 06*

   Sumino's Cancellation Mechanism in an Anomaly-Free Model

   Yoshio Koide🇯🇵

   An interesting family gauge boson (FGB) model (Model A) has been proposed by Sumino. The model can give FGBs with a considerably low energy scale in spite of the sever constraints form the observed $K^0$-${\bar{K}}^0$ mixing and so on. An essential idea in Model A is in the so-called Sumino cancellation mechanism between QED and FGB diagrams. However, Model A is not anomaly free and, besides, it causes effective interactions with $\Delta N_{\mathrm{family}}=2$. In order to avoid these problems, a revised Sumino model with an inverted mass hierarchy (Model B) has proposed, but, in this time, it cannot satisfy the Sumino cancellation mechanism exactly. In this paper, we propose a revised version of Model B, where the model still keeps anomaly free, but it can exactly satisfy the Sumino mechanism. An effect of the revised model will be confirmed by observations $K^{+}\to {\pi }^{+}{e}^{-}{\mu }^{+}$ and ${\mu }^{-}N\to e^{-}N$.

   hep-phMod.Phys.Lett.A(2017)·1 citation
7. 07*

   Light Cone Distribution Amplitudes of Excited P-Wave Heavy Quarkonia at the Leading Twist

   M. A. Olpak🇹🇷 · A. Ozpineci🇹🇷 · V. Tanriverdi🇹🇷

   Leading twist light cone distribution amplitudes (LCDAs) are key ingredients in calculating various hadronic amplitudes using light cone QCD sum rules. This work concentrates on calculating the leading twist LCDAs of P-wave heavy quarkonia. Quark model wavefunctions for the ground, first and second excited states of P-wave charmonia and bottomonia have been calculated, and are used for calculating the relevant LCDAs and leptonic decay constants.

   hep-phPRD(2017)·12 citations
8. 08*

   Mono-Higgs signature in fermionic dark matter model

   Karim Ghorbani🇮🇷 · Leila Khalkhali🇮🇷

   In light of the Higgs boson discovery, we explore mono-Higgs signature in association with dark matter pair production at the LHC in a renormalizable model with a fermionic dark matter candidate. For two channels with $\gamma \gamma +\text{MET}$ and $b\bar{b}+\text{MET}$ in the final state we simulate the SM backgrounds and signal events at $\sqrt{s}=14$ TeV. We then estimate the LHC sensitivities for various benchmark points for two integrated luminosities $\mathcal{L}=300{\text{fb}}^{-1}$ and $\mathcal{L}=3{\text{ab}}^{-1}$. We constrain the Yukawa coupling of the dark matter-SM interaction, taking into account bounds from mono-Higgs signature, observed dark matter relic density, Higgs physics, perturbativity requirement and electroweak measurements. Concerning the mono-Higgs search, it turns out that the channel with the largest branching ratio, $b\bar{b}$ channel, provides better sensitivity. There are found regions in the parameter space of the model compatible with all the bounds mentioned above which can be reached in future LHC studies.

   hep-phJ.Phys.G(2017)·27 citations
9. 09*

   Applicability of the Wigner functional approach to evolution of quantum fields

   Andrey Leonidov🇷🇺 · Anna Radovskaya🇷🇺

   Evolution of highly excited quantum field is considered in the framework of Keldysh formalism . It is demonstrated that leading order (LO) term of semiclassical approximation appears as well-known Classical Statistical Approximation (CSA). In simple case of spatially homogeneous scalar field analytical expressions for leading and next-to-leading (NLO) order are presented. It is shown that the range of applicability of CSA strongly depends on the properties of the initial state of the system

   hep-phnucl-thEPJ Web Conf.(2016)·6 citations
10. 10*

    The magnetic moments and electromagnetic form factors of the decuplet baryons in chiral perturbation theory

    Hao-Song Li🇨🇳 · Zhan-Wei Liu🇦🇺 · Xiao-Lin Chen🇨🇳 · Wei-Zhen Deng🇨🇳 · Shi-Lin Zhu🇨🇳

    We have systematically investigated the magnetic moments and magnetic form factors of the decuplet baryons to the next-to-next-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. We also calculate the charge and magnetic dipole form factors of the decuplet baryons. Our results may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.

    hep-phhep-exhep-latnucl-ex+1PRD(2017)·22 citations
11. 11*

    Effects of gauge boson mass on chiral and deconfinement phase transitions in QED${}_3$

    Pei-Lin Yin🇨🇳 · Hai-Xiao Xiao🇨🇳 · Hong-Tao Feng🇨🇳 · Hong-Shi Zong🇨🇳

    Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and $\text{d}$-wave superconducting ($\text{d}$SC) phases, the influences of gauge boson mass $m_a$ on chiral symmetry restoration and deconfinement phase transitions in QED${}_3$ are investigated simultaneously within a unified framework, i.e., Dyson-Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass $m_a$ is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors $N_f^c$ decreases as the gauge boson mass $m_a$ increases and there exists a boundary that separates the $N_f^c$-$m_a$ plane into chiral symmetry breaking/confinement region for ($N_f^c$, $m_a$) below the boundary and chiral symmetry restoration/deconfinement region for ($N_f^c$, $m_a$) above it.

    hep-phJ.Exp.Theor.Phys.(2017)·1 citation
12. 12*

    Saturation effects in low-x DIS structure functions and related hadronic total cross sections

    Francesco Giovanni Celiberto🇮🇹 · Laszlo Jenkovszky🇺🇦 · Volodymyr Myronenko🇩🇪

    High-energy nucleon total cross sections are related to low-x DIS structure functions by using the additive quark model.

    hep-phEPJ Web Conf.(2016)·28 citations
13. 13*

    Four-quark structure of Zc(3900), Z(4430) and Xb(5568) states

    Fabian Goerke🇩🇪 · Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jurgen G. Korner🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Pietro Santorelli🇮🇹

    We examine the four-quark structure of the recently discovered charged $Z_c(3900)$, $Z(4430)$, and $X_b(5568)$ states. We calculate the widths of the strong decays $Z_c^{+}\to J/\psi {\pi }^{+}$ (${\eta }_c{\rho }^{+}$, ${\bar{D}}^0{D}^{\ast +}$, ${\bar{D}}^{\ast 0}{D}^{+}$), $Z(4430{)}^{+}\to J/\psi {\pi }^{+}$ ($\psi (2s){\pi }^{+}$), and $X_b^{+}\to B_s{\pi }^{+}$ within a covariant quark model previously developed by us. We find that the tetraquark-type current widely used in the literature for the $Z_c(3900)$ leads to a significant suppression of the $\bar{D}{D}^{\ast }$ and ${\bar{D}}^{\ast }D$ modes. Contrary to this a molecular-type current provides an enhancement by a factor of 6-7 for the $\bar{D}{D}^{\ast }$ modes compared with the $Z_c^{+}\to J/\psi {\pi }^{+}$, ${\eta }_c{\rho }^{+}$ modes in agreement with recent experimental data from the BESIII Collaboration. In case of the $Z(4430)$ state we test a sensitivity of the ratio $R_Z$ of the $Z(4430{)}^{+}\to \psi (2s){\pi }^{+}$ and $Z(4430{)}^{+}\to J/\psi {\pi }^{+}$ decay rates to a choice of the size parameter ${\Lambda }_{Z(4430)}$ of the $Z(4430)$. Using upper constraint for the sum of these two modes deduced from the LHCb Collaboration data we find that $R_Z$ varies from 4.64 to 4.08 when ${\Lambda }_{Z(4430)}$ changes from 2.2 to 3.2 GeV. Also we make the prediction for the $Z(4430{)}^{+}\to D^{\ast +}{\bar{D}}^{\ast 0}$ decay rate.

    hep-phPRD(2016)·55 citations
14. 14*

    From pQCD to neutron stars: matching equations of state to constrain global star properties

    Tyler Gorda🇺🇸

    The equation of state (EoS) of quantum chromodynamics (QCD) at zero temperature can be calculated in two different perturbative regimes: for small values of the baryon chemical potential $\mu$, one may use chiral perturbation theory (ChEFT); and for large values of $\mu$, one may use perturbative QCD (pQCD). There is, however, a gap for $\mu \in (0.97\text{ GeV},2.6\text{ GeV})$, where these theories becomes non-perturbative, and where there is currently no known microscopic description of QCD matter. Unfortunately, this interval obscures the values of $\mu$ found within the cores of neutron stars (NSs). In this thesis, we argue that thermodynamic matching of the ChEFT and pQCD EoSs is a legitimate way to obtain quantitative constraints on the non-pertubative QCD EoS. Moreover, we argue that this method is effective, verifiable, and systematically improvable. First, we carry out a simplified matching procedure in QCD-like theories that can be simulated on the lattice without a sign problem. Our calculated pressure band serves as a prediction for lattice-QCD practitioners and will allow them to verify or refute the simplified procedure. Second, we apply the state-of-the-art matched EoS of Kurkela et al. (2014) to rotating NSs. This allows us to obtain bounds on observable NS properties, as well as point towards future observations that would more tightly constrain the current state-of-the-art EoS band. Finally, as evidence of the ability to improve the procedure, we carry out calculations in pQCD to improve the zero-temperature pressure. We calculate the full $\mathcal{O}(g^6{\ln }^{2}g)$ contribution to the pQCD pressure for $n_f$ massless quarks, as well as a significant portion of the $\mathcal{O}(g^6\ln g)$ piece and even some of the $\mathcal{O}(g^6)$ piece.

    ↳ nucl-thastro-ph.HEhep-ph0 citations
15. 15*

    BCJ relations from a new symmetry of gauge-theory amplitudes

    Robert W. Brown🇺🇸 · Stephen G. Naculich🇺🇸

    We introduce a new set of symmetries obeyed by tree-level gauge-theory amplitudes involving at least one gluon. The symmetry acts as a momentum-dependent shift on the color factors of the amplitude. Using the radiation vertex expansion, we prove the invariance under this color-factor shift of the $n$-gluon amplitude, as well as amplitudes involving massless or massive particles in an arbitrary representation of the gauge group with spin zero, one-half, or one. The Bern-Carrasco-Johansson relations are a direct consequence of this symmetry. We also introduce the cubic vertex expansion of an amplitude, and use it to derive a generalized-gauge-invariant constraint on the kinematic numerators of the amplitude. We show that the amplitudes of the bi-adjoint scalar theory are invariant under the color-factor symmetry, and use this to derive the null eigenvectors of the propagator matrix. We generalize the color-factor shift to loop level, and prove the invariance under this shift of one-loop $n$-gluon amplitudes in any theory that admits a color-kinematic-dual representation of numerators. We show that the one-loop color-factor symmetry implies known relations among the integrands of one-loop color-ordered amplitudes.

    ↳ hep-thhep-phJHEP(2016)·21 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.