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They are all undergraduates and will need visas. To get a visa they will need a sponsor. SLAC cannot sponsor undergraduates. They will promptly investigate at their end obtaining visas for the 9 students; there are 2 additional students who do have their Bachelors who might be interested (I assume that SLAC could help them with visas);
They can work remotely. As for accounts at SLAC they will need a SLAC ID. As far as I know there is not a block against Indian undergrads getting a SLAC ID. To get this they will need to fill out the FACTS DoE doc and have a sponsor. Once they have a SLAC ID, they will be able to get an unprivileged SLAC account (will need sponsor) which will help with working remotely until they get a visa.
CVs
See here.