Publications de Mithilesh Nayak

Bound states and deconfined spinons in the dynamical structure factor of the J1-J2 spin-1 chain

Henrik Moodysson Rønnow, Frédéric Mila, Mithilesh Nayak

Using a time-dependent density matrix renormalization group approach, we study the dynamical structure factor of the J1-J2 spin-1 chain. As J2 increases, the magnon mode develops incommensurability. The system undergoes a first-order transition at J2=0.76J ...

2025

Field-induced bound-state condensation and spin-nematic phase in SrCu2(BO3)2 revealed by neutron scattering up to 25.9 T

Henrik Moodysson Rønnow, Frédéric Mila, Bruce Normand, Ellen Fogh, Jian Rui Soh, Mithilesh Nayak, Alexandra Angeline Turrini

In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the Bose-Einstein condensation (BEC) of magnon excitations. In the strongly frustrated system SrCu2(BO3)(2), no clear magnon BEC could be observed, point ...

Nature Portfolio2024

Numerical investigation of bound states in quantum magnets

Mithilesh Nayak

Bound-states of particles are an interesting problem in quantum mechanics dating back to 1931 Bethe's solution of spin-1/2 Heisenberg chain. These exotic composite states are realized in quantum magnets and are detectable in inelastic neutron scattering (I ...

EPFL2023

Possibility to detect the bound state of the Heisenberg ferromagnetic chain at intermediate temperature

Frédéric Mila, Mithilesh Nayak

Motivated by the lack of direct evidence with inelastic neutron scattering of the well documented bound state of Heisenberg ferromagnets, we use the time-dependent thermal density matrix renormalization group algorithm to study the temperature dependence o ...

2022

Magnetic-Field-Induced Bound States in Spin-1/2 Ladders

Frédéric Mila, Mithilesh Nayak

Motivated by the recently observed intriguing mode splittings in a magnetic field with inelastic neutron scattering in the spin ladder compound (C5H12N)(2) CuBr4 (BPCB), we investigate the nature of the spin ladder excitations using a density matrix renorm ...

2020

Search for CP violation with kinematic asymmetries in the D-0 -> K+K- pi(+)pi(-) decay

Olivier Schneider, Mithilesh Nayak, Yiming Li, Sun Hee Kim, Mingkui Wang, Chao Wang, Kyung Taek Cho, Tagir Aushev, Yifei Guan, Jun Yong Kim

We search for CP violation in the singly-Cabibbo-suppressed decay D-0 -> K+K-pi(+)pi(-) using data corresponding to an integrated luminosity of 988 fb(-1) collected by the Belle detector at the KEKB e(+)e(-). We measure a set of five kinematically dependen ...

American Physical Society2019

Transverse momentum dependent production cross sections of charged pions, kaons and protons produced in inclusive e(+)e(-) annihilation at root s=10.58 GeV

Olivier Schneider, Mithilesh Nayak, Yiming Li, Mingkui Wang, Chao Wang, Tagir Aushev, Sun Hee Kim, Jun Yong Kim, Ji Hyun Kim, Donghyun Kim

We report measurements of the production cross sections of charged pions, kaons, and protons as a function of fractional energy, the event-shape variable called thrust, and the transverse momentum with respect to the thrust axis. These measurements access ...

American Physical Society2019

Search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi(-) decays

Olivier Schneider, Mithilesh Nayak, Yiming Li, Sun Hee Kim, Mingkui Wang, Chao Wang, Kyung Taek Cho, Tagir Aushev, Yong Chan Choi, Linlin Cao

We report the results of a search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi thorn p-decays. This study is based on a data sample corresponding to an integrated luminosity of 711 fb(-1), collected at the Upsilon(4S) resonance with the Belle detector a ...

American Physical Society2019

Search for a Light CP-odd Higgs Boson and Low-Mass Dark Matter at the Belle Experiment

Olivier Schneider, Yiming Li, Roberto Gargiani, Chao Wang, Mithilesh Nayak, Gaétan Charles Antoine Giriat, Tagir Aushev, Sun Hee Kim, Tara Nanut, Ke Huang

We report on the first Belle search for a light CP-odd Higgs boson, A(0), that decays into low mass dark matter, chi, in final states with a single photon and missing energy. We search for events produced via the dipion transition (sic)(2S) -> (sic)(1S)pi( ...

2019

Measurement of cos 2 beta in B-0 -> D((*))h(0) with D -> K-S(0)pi(+) pi(-) decays by a combined time-dependent Dalitz plot analysis of BABAR and Belle data

Olivier Schneider, Roberto Gargiani, Yiming Li, Mingkui Wang, Mithilesh Nayak, Chao Wang, Gaétan Charles Antoine Giriat, Tagir Aushev, Greig Alan Cowan, Sun Hee Kim

We report measurements of sin 2 beta and cos 2 beta using a time-dependent Dalitz plot analysis of B-0 -> D((*))h(0) with D -> K-S(0)pi(+)pi(-) decays, where the light unflavored and neutral hadron h(0) is a pi(0),eta, or omega meson. The analysis uses a c ...

American Physical Society2018